Programs & Examples On #Segment

Segment is an ambiguous tag and one should refrain from using it. It has several, very different, meanings in CS. Please try and pick a more accurate tag for your post.

Adding a UISegmentedControl to UITableView

   self.tableView.tableHeaderView = segmentedControl; 

If you want it to obey your width and height properly though enclose your segmentedControl in a UIView first as the tableView likes to mangle your view a bit to fit the width.

enter image description here enter image description here

ERROR Error: Uncaught (in promise), Cannot match any routes. URL Segment

When you use routerLink like this, then you need to pass the value of the route it should go to. But when you use routerLink with the property binding syntax, like this: [routerLink], then it should be assigned a name of the property the value of which will be the route it should navigate the user to.

So to fix your issue, replace this routerLink="['/about']" with routerLink="/about" in your HTML.

There were other places where you used property binding syntax when it wasn't really required. I've fixed it and you can simply use the template syntax below:

<nav class="main-nav>
  <ul 
    class="main-nav__list" 
    ng-sticky 
    addClass="main-sticky-link" 
    [ngClass]="ref.click ? 'Navbar__ToggleShow' : ''">
    <li class="main-nav__item" routerLinkActive="active">
      <a class="main-nav__link" routerLink="/">Home</a>
    </li>
    <li class="main-nav__item" routerLinkActive="active"> 
      <a class="main-nav__link" routerLink="/about">About us</a>
    </li>
  </ul>
</nav>

It also needs to know where exactly should it load the template for the Component corresponding to the route it has reached. So for that, don't forget to add a <router-outlet></router-outlet>, either in your template provided above or in a parent component.

There's another issue with your AppRoutingModule. You need to export the RouterModule from there so that it is available to your AppModule when it imports it. To fix that, export it from your AppRoutingModule by adding it to the exports array.

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { RouterModule, Routes } from '@angular/router';
import { MainLayoutComponent } from './layout/main-layout/main-layout.component';
import { AboutComponent } from './components/about/about.component';
import { WhatwedoComponent } from './components/whatwedo/whatwedo.component';
import { FooterComponent } from './components/footer/footer.component';
import { ProjectsComponent } from './components/projects/projects.component';
const routes: Routes = [
  { path: 'about', component: AboutComponent },
  { path: 'what', component: WhatwedoComponent },
  { path: 'contacts', component: FooterComponent },
  { path: 'projects', component: ProjectsComponent},
];

@NgModule({
  imports: [
    CommonModule,
    RouterModule.forRoot(routes),
  ],
  exports: [RouterModule],
  declarations: []
})
export class AppRoutingModule { }

Uncaught SyntaxError: Unexpected end of JSON input at JSON.parse (<anonymous>)

You define var scatterSeries = [];, and then try to parse it as a json string at console.info(JSON.parse(scatterSeries)); which obviously fails. The variable is converted to an empty string, which causes an "unexpected end of input" error when trying to parse it.

Get Path from another app (WhatsApp)

You can try this it will help for you.You can't get path from WhatsApp directly.If you need an file path first copy file and send new file path. Using the code below

 public static String getFilePathFromURI(Context context, Uri contentUri) {
    String fileName = getFileName(contentUri);
    if (!TextUtils.isEmpty(fileName)) {
        File copyFile = new File(TEMP_DIR_PATH  + fileName+".jpg");
        copy(context, contentUri, copyFile);
        return copyFile.getAbsolutePath();
    }
    return null;
}

public static String getFileName(Uri uri) {
    if (uri == null) return null;
    String fileName = null;
    String path = uri.getPath();
    int cut = path.lastIndexOf('/');
    if (cut != -1) {
        fileName = path.substring(cut + 1);
    }
    return fileName;
}

public static void copy(Context context, Uri srcUri, File dstFile) {
    try {
        InputStream inputStream = context.getContentResolver().openInputStream(srcUri);
        if (inputStream == null) return;
        OutputStream outputStream = new FileOutputStream(dstFile);
        IOUtils.copy(inputStream, outputStream);
        inputStream.close();
        outputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Then IOUtils class is like below

public class IOUtils {



private static final int BUFFER_SIZE = 1024 * 2;

private IOUtils() {
    // Utility class.
}

public static int copy(InputStream input, OutputStream output) throws Exception, IOException {
    byte[] buffer = new byte[BUFFER_SIZE];

    BufferedInputStream in = new BufferedInputStream(input, BUFFER_SIZE);
    BufferedOutputStream out = new BufferedOutputStream(output, BUFFER_SIZE);
    int count = 0, n = 0;
    try {
        while ((n = in.read(buffer, 0, BUFFER_SIZE)) != -1) {
            out.write(buffer, 0, n);
            count += n;
        }
        out.flush();
    } finally {
        try {
            out.close();
        } catch (IOException e) {
            Log.e(e.getMessage(), e.toString());
        }
        try {
            in.close();
        } catch (IOException e) {
            Log.e(e.getMessage(), e.toString());
        }
    }
    return count;
}


}

Error: Cannot match any routes. URL Segment: - Angular 2

please modify your router.module.ts as:

const routes: Routes = [
{
    path: '',
    redirectTo: 'one',
    pathMatch: 'full'
},
{
    path: 'two',
    component: ClassTwo, children: [
        {
            path: 'three',
            component: ClassThree,
            outlet: 'nameThree',
        },
        {
            path: 'four',
            component: ClassFour,
            outlet: 'nameFour'
        },
        {
           path: '',
           redirectTo: 'two',
           pathMatch: 'full'
        }
    ]
},];

and in your component1.html

<h3>In One</h3>

<nav>
    <a routerLink="/two" class="dash-item">...Go to Two...</a>
    <a routerLink="/two/three" class="dash-item">... Go to THREE...</a>
    <a routerLink="/two/four" class="dash-item">...Go to FOUR...</a>
</nav>

<router-outlet></router-outlet>                   // Successfully loaded component2.html
<router-outlet name="nameThree" ></router-outlet> // Error: Cannot match any routes. URL Segment: 'three'
<router-outlet name="nameFour" ></router-outlet>  // Error: Cannot match any routes. URL Segment: 'three'

ValueError: cannot reshape array of size 30470400 into shape (50,1104,104)

In Matrix terms, the number of elements always has to equal the product of the number of rows and columns. In this particular case, the condition is not matching.

WARNING: sanitizing unsafe style value url

There is an open issue to only print this warning if there was actually something sanitized: https://github.com/angular/angular/pull/10272

I didn't read in detail when this warning is printed when nothing was sanitized.

Import error No module named skimage

For OSX: pip install scikit-image

and then run python to try following

from skimage.feature import corner_harris, corner_peaks

The response content cannot be parsed because the Internet Explorer engine is not available, or

Yet another method to solve: updating registry. In my case I could not alter GPO, and -UseBasicParsing breaks parts of the access to the website. Also I had a service user without log in permissions, so I could not log in as the user and run the GUI.
To fix,

  1. log in as a normal user, run IE setup.
  2. Then export this registry key: HKEY_USERS\S-1-5-21-....\SOFTWARE\Microsoft\Internet Explorer
  3. In the .reg file that is saved, replace the user sid with the service account sid
  4. Import the .reg file

In the file

How to fix Error: this class is not key value coding-compliant for the key tableView.'

Any chance that you changed the name of your table view from "tableView" to "myTableView" at some point?

How to get current route

In Angular2 Rc1 you can inject RouteSegment and pass them in naviagte method.

constructor(private router:Router,private segment:RouteSegment) {}

  ngOnInit() {
    this.router.navigate(["explore"],this.segment)
  }

Error LNK2019 unresolved external symbol _main referenced in function "int __cdecl invoke_main(void)" (?invoke_main@@YAHXZ)

Right click on project. Properties->Configuration Properties->General->Linker.

I found two options needed to be set. Under System: SubSystem = Windows (/SUBSYSTEM:WINDOWS) Under Advanced: EntryPoint = main

How to access URL segment(s) in blade in Laravel 5?

BASED ON LARAVEL 5.7 & ABOVE

To get all segments of current URL:

$current_uri = request()->segments();

To get segment posts from http://example.com/users/posts/latest/

NOTE: Segments are an array that starts at index 0. The first element of array starts after the TLD part of the url. So in the above url, segment(0) will be users and segment(1) will be posts.

//get segment 0
$segment_users = request()->segment(0); //returns 'users'
//get segment 1
$segment_posts = request()->segment(1); //returns 'posts'

You may have noted that the segment method only works with the current URL ( url()->current() ). So I designed a method to work with previous URL too by cloning the segment() method:

public function index()
{
    $prev_uri_segments = $this->prev_segments(url()->previous());
}

 /**
 * Get all of the segments for the previous uri.
 *
 * @return array
 */
public function prev_segments($uri)
{
    $segments = explode('/', str_replace(''.url('').'', '', $uri));

    return array_values(array_filter($segments, function ($value) {
        return $value !== '';
    }));
}

Significance of ios_base::sync_with_stdio(false); cin.tie(NULL);

Lot's of great answer. I just want to add a small note about decoupling the stream.

cin.tie(NULL);

I have faced an issue while decoupling the stream with CodeChef platform. When I submitted my code, the platform response was "Wrong Answer" but after tying the stream and testing the submission. It worked.

So, If anyone wants to untie the stream, the output stream must be flushed.

Edit: I am not familiar with all the platform but this is what I have experienced.

When do I use path params vs. query params in a RESTful API?

The fundamental way to think about this subject is as follows:

A URI is a resource identifier that uniquely identifies a specific instance of a resource TYPE. Like everything else in life, every object (which is an instance of some type), have set of attributes that are either time-invariant or temporal.

In the example above, a car is a very tangible object that has attributes like make, model and VIN - that never changes, and color, suspension etc. that may change over time. So if we encode the URI with attributes that may change over time (temporal), we may end up with multiple URIs for the same object:

GET /cars/honda/civic/coupe/{vin}/{color=red}

And years later, if the color of this very same car is changed to black:

GET /cars/honda/civic/coupe/{vin}/{color=black}

Note that the car instance itself (the object) has not changed - it's just the color that changed. Having multiple URIs pointing to the same object instance will force you to create multiple URI handlers - this is not an efficient design, and is of course not intuitive.

Therefore, the URI should only consist of parts that will never change and will continue to uniquely identify that resource throughout its lifetime. Everything that may change should be reserved for query parameters, as such:

GET /cars/honda/civic/coupe/{vin}?color={black}

Bottom line - think polymorphism.

How to customize the configuration file of the official PostgreSQL Docker image?

I was also using the official image (FROM postgres) and I was able to change the config by executing the following commands.

The first thing is to locate the PostgreSQL config file. This can be done by executing this command in your running database.

SHOW config_file;

I my case it returns /data/postgres/postgresql.conf.

The next step is to find out what is the hash of your running PostgreSQL docker container.

docker ps -a

This should return a list of all the running containers. In my case it looks like this.

...
0ba35e5427d9    postgres    "docker-entrypoint.s…" ....
...

Now you have to switch to the bash inside your container by executing:

docker exec -it 0ba35e5427d9 /bin/bash

Inside the container check if the config is at the correct path and display it.

cat /data/postgres/postgresql.conf

I wanted to change the max connections from 100 to 1000 and the shared buffer from 128MB to 3GB. With the sed command I can do a search and replace with the corresponding variables ins the config.

sed -i -e"s/^max_connections = 100.*$/max_connections = 1000/" /data/postgres/postgresql.conf
sed -i -e"s/^shared_buffers = 128MB.*$/shared_buffers = 3GB/" /data/postgres/postgresql.conf

The last thing we have to do is to restart the database within the container. Find out which version you of PostGres you are using.

cd /usr/lib/postgresql/
ls 

In my case its 12 So you can now restart the database by executing the following command with the correct version in place.

su - postgres -c "PGDATA=$PGDATA /usr/lib/postgresql/12/bin/pg_ctl -w restart"

ggplot2, change title size

+ theme(plot.title = element_text(size=22))

Here is the full set of things you can change in element_text:

element_text(family = NULL, face = NULL, colour = NULL, size = NULL,
  hjust = NULL, vjust = NULL, angle = NULL, lineheight = NULL,
  color = NULL)

How to SSH into Docker?

It is a short way but not permanent

first create a container

docker run  ..... -p 22022:2222 .....

port 22022 on your host machine will map on 2222, we change the ssh port on container later , then on your container executing the following commands

apt update && apt install  openssh-server # install ssh server
passwd #change root password

in file /etc/ssh/sshd_config change these : uncomment Port and change it to 2222

Port 2222

uncomment PermitRootLogin to

PermitRootLogin yes

and finally restart ssh server

/etc/init.d/ssh start

you can login to your container now

ssh -p 2022 root@HostIP

Remember : if you restart the container you need to restart ssh server again

How to get file name from file path in android

Old thread but thought I would update;

 File theFile = .......
 String theName = theFile.getName();  // Get the file name
 String thePath = theFile.getAbsolutePath(); // Get the full

More info can be found here; Android File Class

Command failed due to signal: Segmentation fault: 11

For anyone else coming across this... I found the issue was caused by importing a custom framework, I have no idea how to correct it. But simply removing the import and any code referencing items from the framework fixes the issue.

(?°?°)?? ???

Hope this can save someone a few hours chasing down which line is causing the issue.

swift How to remove optional String Character

Actually when you define any variable as a optional then you need to unwrap that optional value. To fix this problem either you have to declare variable as non option or put !(exclamation) mark behind the variable to unwrap the option value.

var temp : String? // This is an optional.
temp = "I am a programer"                
print(temp) // Optional("I am a programer")

var temp1 : String! // This is not optional.
temp1 = "I am a programer"
print(temp1) // "I am a programer"

resize2fs: Bad magic number in super-block while trying to open

In Centos 7 default filesystem is xfs.

xfs file system support only extend not reduce. So if you want to resize the filesystem use xfs_growfs rather than resize2fs.

xfs_growfs /dev/root_vg/root 

Note: For ext4 filesystem use

resize2fs /dev/root_vg/root

Timestamp with a millisecond precision: How to save them in MySQL

CREATE TABLE fractest( c1 TIME(3), c2 DATETIME(3), c3 TIMESTAMP(3) );

INSERT INTO fractest VALUES
('17:51:04.777', '2018-09-08 17:51:04.777', '2018-09-08 17:51:04.777');

FATAL ERROR: CALL_AND_RETRY_LAST Allocation failed - process out of memory

I was seeing this issue when I was creating a bundle to react-native. Things I tried and didn't work:

  1. Increasing the node --max_old_space_size, intrestingly this worked locally for me but failed on jenkins and I'm still not sure what goes wrong with jenkins
  2. Some places mentioned to downgrade the version of node to 6.9.1 and that didn't work for me either. I would just like to put this here as it might work for you.

Thing that did work for me: I was importing a really big file in the code. The way I resolved it was by including it in the ignore list in .babelrc something like this:

{
    "presets": ["react-native"],
    "plugins": ["transform-inline-environment-variables"],
    "ignore": ["*.json","filepathToIgnore.ext"]
}

It was a .js file which did not really needed transpiling and adding it to the ignore list did help.

dyld: Library not loaded: @rpath/libswiftCore.dylib

In my case, This is a bug of the early version iOS13.

https://forums.developer.apple.com/thread/128435

kambala

Mar 25, 2020 12:41 AM

FYI this is fixed in 13.4 release

Problems using Maven and SSL behind proxy

ymptom: After configuring Nexus to serve SSL maven builds fail with "peer not authenticated" or "PKIX path building failed".

This is usually caused by using a self signed SSL certificate on Nexus. Java does not consider these to be a valid certificates, and will not allow connecting to server's running them by default.

You have a few choices here to fix this:

  1. Add the public certificate of the Nexus server to the trust store of the Java running Maven
  2. Get the certificate on Nexus signed by a root certificate authority such as Verisign
  3. Tell Maven to accept the certificate even though it isn't signed

For option 1 you can use the keytool command and follow the steps in the below article.

Explicitly Trusting a Self-Signed or Private Certificate in a Java Based Client

For option 3, invoke Maven with "-Dmaven.wagon.http.ssl.insecure=true". If the host name configured in the certificate doesn't match the host name Nexus is running on you may also need to add "-Dmaven.wagon.http.ssl.allowall=true".

Note: These additional parameters are initialized in static initializers, so they have to be passed in via the MAVEN_OPTS environment variable. Passing them on the command line to Maven will not work.

See here for more information:

http://maven.apache.org/wagon/wagon-providers/wagon-http/

ORA-01652: unable to extend temp segment by 128 in tablespace SYSTEM: How to extend?

Each tablespace has one or more datafiles that it uses to store data.

The max size of a datafile depends on the block size of the database. I believe that, by default, that leaves with you with a max of 32gb per datafile.

To find out if the actual limit is 32gb, run the following:

select value from v$parameter where name = 'db_block_size';

Compare the result you get with the first column below, and that will indicate what your max datafile size is.

I have Oracle Personal Edition 11g r2 and in a default install it had an 8,192 block size (32gb per data file).

Block Sz   Max Datafile Sz (Gb)   Max DB Sz (Tb)

--------   --------------------   --------------

   2,048                  8,192          524,264

   4,096                 16,384        1,048,528

   8,192                 32,768        2,097,056

  16,384                 65,536        4,194,112

  32,768                131,072        8,388,224

You can run this query to find what datafiles you have, what tablespaces they are associated with, and what you've currrently set the max file size to (which cannot exceed the aforementioned 32gb):

select bytes/1024/1024 as mb_size,
       maxbytes/1024/1024 as maxsize_set,
       x.*
from   dba_data_files x

MAXSIZE_SET is the maximum size you've set the datafile to. Also relevant is whether you've set the AUTOEXTEND option to ON (its name does what it implies).

If your datafile has a low max size or autoextend is not on you could simply run:

alter database datafile 'path_to_your_file\that_file.DBF' autoextend on maxsize unlimited;

However if its size is at/near 32gb an autoextend is on, then yes, you do need another datafile for the tablespace:

alter tablespace system add datafile 'path_to_your_datafiles_folder\name_of_df_you_want.dbf' size 10m autoextend on maxsize unlimited;

Command Prompt Error 'C:\Program' is not recognized as an internal or external command, operable program or batch file

If a directory has spaces in, put quotes around it. This includes the program you're calling, not just the arguments

"C:\Program Files\IAR Systems\Embedded Workbench 7.0\430\bin\icc430.exe" "F:\CP001\source\Meter\Main.c" -D Hardware_P20E -D Calibration_code -D _Optical -D _Configuration_TS0382 -o "F:\CP001\Temp\C20EO\Obj\" --no_cse --no_unroll --no_inline --no_code_motion --no_tbaa --debug -D__MSP430F425 -e --double=32 --dlib_config "C:\Program Files\IAR Systems\Embedded Workbench 7.0\430\lib\dlib\dl430fn.h" -Ol --multiplier=16 --segment __data16=DATA16 --segment __data20=DATA20

upstream sent too big header while reading response header from upstream

I am not sure that the issue is related to what header php is sending. Make sure that the buffering is enabled. The simple way is to create a proxy.conf file:

proxy_redirect          off;
proxy_set_header        Host            $host;
proxy_set_header        X-Real-IP       $remote_addr;
proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
client_max_body_size    100m;
client_body_buffer_size 128k;
proxy_connect_timeout   90;
proxy_send_timeout      90;
proxy_read_timeout      90;
proxy_buffering         on;
proxy_buffer_size       128k;
proxy_buffers           4 256k;
proxy_busy_buffers_size 256k;

And a fascgi.conf file:

fastcgi_param  SCRIPT_FILENAME    $document_root$fastcgi_script_name;
fastcgi_param  QUERY_STRING       $query_string;
fastcgi_param  REQUEST_METHOD     $request_method;
fastcgi_param  CONTENT_TYPE       $content_type;
fastcgi_param  CONTENT_LENGTH     $content_length;
fastcgi_param  SCRIPT_NAME        $fastcgi_script_name;
fastcgi_param  REQUEST_URI        $request_uri;
fastcgi_param  DOCUMENT_URI       $document_uri;
fastcgi_param  DOCUMENT_ROOT      $document_root;
fastcgi_param  SERVER_PROTOCOL    $server_protocol;
fastcgi_param  GATEWAY_INTERFACE  CGI/1.1;
fastcgi_param  SERVER_SOFTWARE    nginx/$nginx_version;
fastcgi_param  REMOTE_ADDR        $remote_addr;
fastcgi_param  REMOTE_PORT        $remote_port;
fastcgi_param  SERVER_ADDR        $server_addr;
fastcgi_param  SERVER_PORT        $server_port;
fastcgi_param  SERVER_NAME        $server_name;
fastcgi_buffers 128 4096k;
fastcgi_buffer_size 4096k;
fastcgi_index  index.php;
fastcgi_param  REDIRECT_STATUS    200;

Next you need to call them in your default config server this way:

http {
  include    /etc/nginx/mime.types;
  include    /etc/nginx/proxy.conf;
  include    /etc/nginx/fastcgi.conf;
  index    index.html index.htm index.php;
  log_format   main '$remote_addr - $remote_user [$time_local]  $status '
    '"$request" $body_bytes_sent "$http_referer" '
    '"$http_user_agent" "$http_x_forwarded_for"';
  #access_log   /logs/access.log  main;
  sendfile     on;
  tcp_nopush   on;
 # ........
}

How to add label in chart.js for pie chart

EDIT: http://jsfiddle.net/nCFGL/223/ My Example.

You should be able to like follows:

var pieData = [{
    value: 30,
    color: "#F38630",
    label: 'Sleep',
    labelColor: 'white',
    labelFontSize: '16'
  },
  ...
];

Include the Chart.js located at:

https://github.com/nnnick/Chart.js/pull/35

Drawing Circle with OpenGL

There is another way to draw a circle - draw it in fragment shader. Create a quad:

float right = 0.5;
float bottom = -0.5;
float left = -0.5;
float top = 0.5;
float quad[20] = {
    //x, y, z, lx, ly
    right, bottom, 0, 1.0, -1.0,
    right, top, 0, 1.0, 1.0,
    left, top, 0, -1.0, 1.0,
    left, bottom, 0, -1.0, -1.0,
};

Bind VBO:

unsigned int glBuffer;
glGenBuffers(1, &glBuffer);
glBindBuffer(GL_ARRAY_BUFFER, glBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(float)*20, quad, GL_STATIC_DRAW);

and draw:

#define BUFFER_OFFSET(i) ((char *)NULL + (i))
glEnableVertexAttribArray(ATTRIB_VERTEX);
glEnableVertexAttribArray(ATTRIB_VALUE);
glVertexAttribPointer(ATTRIB_VERTEX , 3, GL_FLOAT, GL_FALSE, 20, 0);
glVertexAttribPointer(ATTRIB_VALUE , 2, GL_FLOAT, GL_FALSE, 20, BUFFER_OFFSET(12));
glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

Vertex shader

attribute vec2 value;
uniform mat4 viewMatrix;
uniform mat4 projectionMatrix;
varying vec2 val;
void main() {
    val = value;
    gl_Position = projectionMatrix*viewMatrix*vertex;
}

Fragment shader

varying vec2 val;
void main() {
    float R = 1.0;
    float R2 = 0.5;
    float dist = sqrt(dot(val,val));
    if (dist >= R || dist <= R2) {
        discard;
    }
    float sm = smoothstep(R,R-0.01,dist);
    float sm2 = smoothstep(R2,R2+0.01,dist);
    float alpha = sm*sm2;
    gl_FragColor = vec4(0.0, 0.0, 1.0, alpha);
}

Don't forget to enable alpha blending:

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);

UPDATE: Read more

how to get the base url in javascript

To get exactly the same thing as base_url of codeigniter, you can do:

var base_url = window.location.origin + '/' + window.location.pathname.split ('/') [1] + '/';

this will be more useful if you work on pure Javascript file.

How to get id from URL in codeigniter?

In codeigniter you can't pass parameters in the url as you are doing in core php.So remove the "?" and "product_id" and simply pass the id.If you want more security you can encrypt the id and pass it.

Node.js - Maximum call stack size exceeded

You should wrap your recursive function call into a

  • setTimeout,
  • setImmediate or
  • process.nextTick

function to give node.js the chance to clear the stack. If you don't do that and there are many loops without any real async function call or if you do not wait for the callback, your RangeError: Maximum call stack size exceeded will be inevitable.

There are many articles concerning "Potential Async Loop". Here is one.

Now some more example code:

// ANTI-PATTERN
// THIS WILL CRASH

var condition = false, // potential means "maybe never"
    max = 1000000;

function potAsyncLoop( i, resume ) {
    if( i < max ) {
        if( condition ) { 
            someAsyncFunc( function( err, result ) { 
                potAsyncLoop( i+1, callback );
            });
        } else {
            // this will crash after some rounds with
            // "stack exceed", because control is never given back
            // to the browser 
            // -> no GC and browser "dead" ... "VERY BAD"
            potAsyncLoop( i+1, resume ); 
        }
    } else {
        resume();
    }
}
potAsyncLoop( 0, function() {
    // code after the loop
    ...
});

This is right:

var condition = false, // potential means "maybe never"
    max = 1000000;

function potAsyncLoop( i, resume ) {
    if( i < max ) {
        if( condition ) { 
            someAsyncFunc( function( err, result ) { 
                potAsyncLoop( i+1, callback );
            });
        } else {
            // Now the browser gets the chance to clear the stack
            // after every round by getting the control back.
            // Afterwards the loop continues
            setTimeout( function() {
                potAsyncLoop( i+1, resume ); 
            }, 0 );
        }
    } else {
        resume();
    }
}
potAsyncLoop( 0, function() {
    // code after the loop
    ...
});

Now your loop may become too slow, because we loose a little time (one browser roundtrip) per round. But you do not have to call setTimeout in every round. Normally it is o.k. to do it every 1000th time. But this may differ depending on your stack size:

var condition = false, // potential means "maybe never"
    max = 1000000;

function potAsyncLoop( i, resume ) {
    if( i < max ) {
        if( condition ) { 
            someAsyncFunc( function( err, result ) { 
                potAsyncLoop( i+1, callback );
            });
        } else {
            if( i % 1000 === 0 ) {
                setTimeout( function() {
                    potAsyncLoop( i+1, resume ); 
                }, 0 );
            } else {
                potAsyncLoop( i+1, resume ); 
            }
        }
    } else {
        resume();
    }
}
potAsyncLoop( 0, function() {
    // code after the loop
    ...
});

Trying to check if username already exists in MySQL database using PHP

TRY THIS ONE

 mysql_connect('localhost','dbuser','dbpass');

$query = "SELECT username FROM Users WHERE username='".$username."'";
mysql_select_db('dbname');

    $result=mysql_query($query);

   if (mysql_num_rows($query) != 0)
   {
     echo "Username already exists";
    }

    else
   {
     ...
    }

Correct way of looping through C++ arrays

sizeof tells you the size of a thing, not the number of elements in it. A more C++11 way to do what you are doing would be:

#include <array>
#include <string>
#include <iostream>

int main()
{
    std::array<std::string, 3> texts { "Apple", "Banana", "Orange" };
    for (auto& text : texts) {
        std::cout << text << '\n';
    }
    return 0;
}

ideone demo: http://ideone.com/6xmSrn

Overlay normal curve to histogram in R

You just need to find the right multiplier, which can be easily calculated from the hist object.

myhist <- hist(mtcars$mpg)
multiplier <- myhist$counts / myhist$density
mydensity <- density(mtcars$mpg)
mydensity$y <- mydensity$y * multiplier[1]

plot(myhist)
lines(mydensity)

enter image description here

A more complete version, with a normal density and lines at each standard deviation away from the mean (including the mean):

myhist <- hist(mtcars$mpg)
multiplier <- myhist$counts / myhist$density
mydensity <- density(mtcars$mpg)
mydensity$y <- mydensity$y * multiplier[1]

plot(myhist)
lines(mydensity)

myx <- seq(min(mtcars$mpg), max(mtcars$mpg), length.out= 100)
mymean <- mean(mtcars$mpg)
mysd <- sd(mtcars$mpg)

normal <- dnorm(x = myx, mean = mymean, sd = mysd)
lines(myx, normal * multiplier[1], col = "blue", lwd = 2)

sd_x <- seq(mymean - 3 * mysd, mymean + 3 * mysd, by = mysd)
sd_y <- dnorm(x = sd_x, mean = mymean, sd = mysd) * multiplier[1]

segments(x0 = sd_x, y0= 0, x1 = sd_x, y1 = sd_y, col = "firebrick4", lwd = 2)

Color Tint UIButton Image

If you have a custom button with a background image.You can set the tint color of your button and override the image with following .

In assets select the button background you want to set tint color.

In the attribute inspector of the image set the value render as to "Template Image"

enter image description here

Now whenever you setbutton.tintColor = UIColor.red you button will be shown in red.

Playing m3u8 Files with HTML Video Tag

Use Flowplayer:

<link rel="stylesheet" href="//releases.flowplayer.org/7.0.4/commercial/skin/skin.css">
    <style>

   </style>
   <script src="//code.jquery.com/jquery-1.12.4.min.js"></script>
  <script src="//releases.flowplayer.org/7.0.4/commercial/flowplayer.min.js"></script>
  <script src="//releases.flowplayer.org/hlsjs/flowplayer.hlsjs.min.js"></script> 
  <script>
  flowplayer(function (api) {
    api.on("load", function (e, api, video) {
      $("#vinfo").text(api.engine.engineName + " engine playing " + video.type);
    }); });
  </script>

<div class="flowplayer fixed-controls no-toggle no-time play-button obj"
      style="    width: 85.5%;
    height: 80%;
    margin-left: 7.2%;
    margin-top: 6%;
    z-index: 1000;" data-key="$812975748999788" data-live="true" data-share="false" data-ratio="0.5625"  data-logo="">
      <video autoplay="true" stretch="true">

         <source type="application/x-mpegurl" src="http://live.wmncdn.net/safaritv2/live2.stream/index.m3u8">
      </video>   
   </div>

Different methods are available in flowplayer.org website.

what is Segmentation fault (core dumped)?

"Segmentation fault" means that you tried to access memory that you do not have access to.

The first problem is with your arguments of main. The main function should be int main(int argc, char *argv[]), and you should check that argc is at least 2 before accessing argv[1].

Also, since you're passing in a float to printf (which, by the way, gets converted to a double when passing to printf), you should use the %f format specifier. The %s format specifier is for strings ('\0'-terminated character arrays).

what is the use of $this->uri->segment(3) in codeigniter pagination

In your code $this->uri->segment(3) refers to the pagination offset which you use in your query. According to your $config['base_url'] = base_url().'index.php/papplicant/viewdeletedrecords/' ;, $this->uri->segment(3) i.e segment 3 refers to the offset. The first segment is the controller, second is the method, there after comes the parameters sent to the controllers as segments.

Use URI builder in Android or create URL with variables

for the example in the second Answer I used this technique for the same URL

http://api.example.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7

Uri.Builder builder = new Uri.Builder();
            builder.scheme("https")
                    .authority("api.openweathermap.org")
                    .appendPath("data")
                    .appendPath("2.5")
                    .appendPath("forecast")
                    .appendPath("daily")
                    .appendQueryParameter("q", params[0])
                    .appendQueryParameter("mode", "json")
                    .appendQueryParameter("units", "metric")
                    .appendQueryParameter("cnt", "7")
                    .appendQueryParameter("APPID", BuildConfig.OPEN_WEATHER_MAP_API_KEY);

then after finish building it get it as URL like this

URL url = new URL(builder.build().toString());

and open a connection

  HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

and if link is simple like location uri, for example

geo:0,0?q=29203

Uri geoLocation = Uri.parse("geo:0,0?").buildUpon()
            .appendQueryParameter("q",29203).build();

When should an Excel VBA variable be killed or set to Nothing?

I have at least one situation where the data is not automatically cleaned up, which would eventually lead to "Out of Memory" errors. In a UserForm I had:

Public mainPicture As StdPicture
...
mainPicture = LoadPicture(PAGE_FILE)

When UserForm was destroyed (after Unload Me) the memory allocated for the data loaded in the mainPicture was not being de-allocated. I had to add an explicit

mainPicture = Nothing

in the terminate event.

How can I get the iOS 7 default blue color programmatically?

It appears to be [UIColor colorWithRed:0.0 green:122.0/255.0 blue:1.0 alpha:1.0].

screenshot showing Colors window

Parsing Json rest api response in C#

1> Add this namspace. using Newtonsoft.Json.Linq;

2> use this source code.

JObject joResponse = JObject.Parse(response);                   
JObject ojObject = (JObject)joResponse["response"];
JArray array= (JArray)ojObject ["chats"];
int id = Convert.ToInt32(array[0].toString());

Redirect all to index.php using htaccess

To redirect everything that doesnt exist to index.php , you can also use the FallBackResource directive

FallbackResource /index.php

It works same as the ErrorDocument , when you request a non-existent path or file on the server, the directive silently forwords the request to index.php .

If you want to redirect everything (including existant files or folders ) to index.php , you can use something like the following :

RewriteEngine on

RewriteRule ^((?!index\.php).+)$ /index.php [L]

Note the pattern ^((?!index\.php).+)$ matches any uri except index.php we have excluded the destination path to prevent infinite looping error.

Understanding [TCP ACKed unseen segment] [TCP Previous segment not captured]

Another cause of "TCP ACKed Unseen" is the number of packets that may get dropped in a capture. If I run an unfiltered capture for all traffic on a busy interface, I will sometimes see a large number of 'dropped' packets after stopping tshark.

On the last capture I did when I saw this, I had 2893204 packets captured, but once I hit Ctrl-C, I got a 87581 packets dropped message. Thats a 3% loss, so when wireshark opens the capture, its likely to be missing packets and report "unseen" packets.

As I mentioned, I captured a really busy interface with no capture filter, so tshark had to sort all packets, when I use a capture filter to remove some of the noise, I no longer get the error.

error C2220: warning treated as error - no 'object' file generated

As a side-note, you can enable/disable individual warnings using #pragma. You can have a look at the documentation here

From the documentation:

// pragma_warning.cpp
// compile with: /W1
#pragma warning(disable:4700)
void Test() {
   int x;
   int y = x;   // no C4700 here
   #pragma warning(default:4700)   // C4700 enabled after Test ends
}

int main() {
   int x;
   int y = x;   // C4700
}

AngularJS: how to enable $locationProvider.html5Mode with deeplinking

My problem solved with these :

1- Add this to your head :

<base href="/" />

2- Use this in app.config

$locationProvider.html5Mode(true);

String in function parameter

Inside the function parameter list, char arr[] is absolutely equivalent to char *arr, so the pair of definitions and the pair of declarations are equivalent.

void function(char arr[]) { ... }
void function(char *arr)  { ... }

void function(char arr[]);
void function(char *arr);

The issue is the calling context. You provided a string literal to the function; string literals may not be modified; your function attempted to modify the string literal it was given; your program invoked undefined behaviour and crashed. All completely kosher.

Treat string literals as if they were static const char literal[] = "string literal"; and do not attempt to modify them.

Convert ascii char[] to hexadecimal char[] in C

#include <stdio.h>
#include <string.h>

int main(void){
    char word[17], outword[33];//17:16+1, 33:16*2+1
    int i, len;

    printf("Intro word:");
    fgets(word, sizeof(word), stdin);
    len = strlen(word);
    if(word[len-1]=='\n')
        word[--len] = '\0';

    for(i = 0; i<len; i++){
        sprintf(outword+i*2, "%02X", word[i]);
    }
    printf("%s\n", outword);
    return 0;
}

If statement in select (ORACLE)

SELECT (CASE WHEN ISSUE_DIVISION = ISSUE_DIVISION_2 THEN 1 ELSE 0 END) AS ISSUES
    --  <add any columns to outer select from inner query> 
  FROM
 (  -- your query here --
   select 'CARAT Issue Open' issue_comment, ...., ..., 
          substr(gcrs.stream_name,1,case when instr(gcrs.stream_name,' (')=0 then 100 else  instr(gcrs.stream_name,' (')-1 end) ISSUE_DIVISION,
          case when gcrs.STREAM_NAME like 'NON-GT%' THEN 'NON-GT' ELSE gcrs.STREAM_NAME END as ISSUE_DIVISION_2
     from ....
    where UPPER(ISSUE_STATUS) like '%OPEN%'
 )
 WHERE... -- optional --

How to update Python?

I have always just installed the new version on top and never had any issues. Do make sure that your path is updated to point to the new version though.

Where in memory are my variables stored in C?

You got some of these right, but whoever wrote the questions tricked you on at least one question:

  • global variables -------> data (correct)
  • static variables -------> data (correct)
  • constant data types -----> code and/or data. Consider string literals for a situation when a constant itself would be stored in the data segment, and references to it would be embedded in the code
  • local variables(declared and defined in functions) --------> stack (correct)
  • variables declared and defined in main function -----> heap also stack (the teacher was trying to trick you)
  • pointers(ex: char *arr, int *arr) -------> heap data or stack, depending on the context. C lets you declare a global or a static pointer, in which case the pointer itself would end up in the data segment.
  • dynamically allocated space(using malloc, calloc, realloc) --------> stack heap

It is worth mentioning that "stack" is officially called "automatic storage class".

Codeigniter unset session

I use the old PHP way..It unsets all session variables and doesn't require to specify each one of them in an array. And after unsetting the variables we destroy the session

Error: Segmentation fault (core dumped)

In my case: I forgot to activate virtualenv

I installed "pip install example" in the wrong virtualenv

Extract data from XML Clob using SQL from Oracle Database

Try

SELECT EXTRACTVALUE(xmltype(testclob), '/DCResponse/ContextData/Field[@key="Decision"]') 
FROM traptabclob;

Here is a sqlfiddle demo

What are the retransmission rules for TCP?

There's no fixed time for retransmission. Simple implementations estimate the RTT (round-trip-time) and if no ACK to send data has been received in 2x that time then they re-send.

They then double the wait-time and re-send once more if again there is no reply. Rinse. Repeat.

More sophisticated systems make better estimates of how long it should take for the ACK as well as guesses about exactly which data has been lost.

The bottom-line is that there is no hard-and-fast rule about exactly when to retransmit. It's up to the implementation. All retransmissions are triggered solely by the sender based on lack of response from the receiver.

TCP never drops data so no, there is no way to indicate a server should forget about some segment.

Adding an arbitrary line to a matplotlib plot in ipython notebook

Matplolib now allows for 'annotation lines' as the OP was seeking. The annotate() function allows several forms of connecting paths and a headless and tailess arrow, i.e., a simple line, is one of them.

ax.annotate("",
            xy=(0.2, 0.2), xycoords='data',
            xytext=(0.8, 0.8), textcoords='data',
            arrowprops=dict(arrowstyle="-",
                      connectionstyle="arc3, rad=0"),
            )

In the documentation it says you can draw only an arrow with an empty string as the first argument.

From the OP's example:

%matplotlib notebook
import numpy as np
import matplotlib.pyplot as plt

np.random.seed(5)
x = np.arange(1, 101)
y = 20 + 3 * x + np.random.normal(0, 60, 100)
plt.plot(x, y, "o")


# draw vertical line from (70,100) to (70, 250)
plt.annotate("",
              xy=(70, 100), xycoords='data',
              xytext=(70, 250), textcoords='data',
              arrowprops=dict(arrowstyle="-",
                              connectionstyle="arc3,rad=0."), 
              )

# draw diagonal line from (70, 90) to (90, 200)
plt.annotate("",
              xy=(70, 90), xycoords='data',
              xytext=(90, 200), textcoords='data',
              arrowprops=dict(arrowstyle="-",
                              connectionstyle="arc3,rad=0."), 
              )

plt.show()

Example inline image

Just as in the approach in gcalmettes's answer, you can choose the color, line width, line style, etc..

Here is an alteration to a portion of the code that would make one of the two example lines red, wider, and not 100% opaque.

# draw vertical line from (70,100) to (70, 250)
plt.annotate("",
              xy=(70, 100), xycoords='data',
              xytext=(70, 250), textcoords='data',
              arrowprops=dict(arrowstyle="-",
                              edgecolor = "red",
                              linewidth=5,
                              alpha=0.65,
                              connectionstyle="arc3,rad=0."), 
              )

You can also add curve to the connecting line by adjusting the connectionstyle.

segmentation fault : 11

This declaration:

double F[1000][1000000];

would occupy 8 * 1000 * 1000000 bytes on a typical x86 system. This is about 7.45 GB. Chances are your system is running out of memory when trying to execute your code, which results in a segmentation fault.

ORA-01652 Unable to extend temp segment by in tablespace

I found the solution to this. There is a temporary tablespace called TEMP which is used internally by database for operations like distinct, joins,etc. Since my query(which has 4 joins) fetches almost 50 million records the TEMP tablespace does not have that much space to occupy all data. Hence the query fails even though my tablespace has free space.So, after increasing the size of TEMP tablespace the issue was resolved. Hope this helps someone with the same issue. Thanks :)

Loop through files in a folder in matlab

Looping through all the files in the folder is relatively easy:

files = dir('*.csv');
for file = files'
    csv = load(file.name);
    % Do some stuff
end

What's the most elegant way to cap a number to a segment?

A simple way would be to use

Math.max(min, Math.min(number, max));

and you can obviously define a function that wraps this:

function clamp(number, min, max) {
  return Math.max(min, Math.min(number, max));
}

Originally this answer also added the function above to the global Math object, but that's a relic from a bygone era so it has been removed (thanks @Aurelio for the suggestion)

Remove grid, background color, and top and right borders from ggplot2

Here's an extremely simple answer

yourPlot +
  theme(
    panel.border = element_blank(), 
    panel.grid.major = element_blank(),
    panel.grid.minor = element_blank(), 
    axis.line = element_line(colour = "black")
    )

It's that easy. Source: the end of this article

Where is nodejs log file?

For nodejs log file you can use winston and morgan and in place of your console.log() statement user winston.log() or other winston methods to log. For working with winston and morgan you need to install them using npm. Example: npm i -S winston npm i -S morgan

Then create a folder in your project with name winston and then create a config.js in that folder and copy this code given below.

const appRoot = require('app-root-path');
const winston = require('winston');

// define the custom settings for each transport (file, console)
const options = {
  file: {
    level: 'info',
    filename: `${appRoot}/logs/app.log`,
    handleExceptions: true,
    json: true,
    maxsize: 5242880, // 5MB
    maxFiles: 5,
    colorize: false,
  },
  console: {
    level: 'debug',
    handleExceptions: true,
    json: false,
    colorize: true,
  },
};

// instantiate a new Winston Logger with the settings defined above
let logger;
if (process.env.logging === 'off') {
  logger = winston.createLogger({
    transports: [
      new winston.transports.File(options.file),
    ],
    exitOnError: false, // do not exit on handled exceptions
  });
} else {
  logger = winston.createLogger({
    transports: [
      new winston.transports.File(options.file),
      new winston.transports.Console(options.console),
    ],
    exitOnError: false, // do not exit on handled exceptions
  });
}

// create a stream object with a 'write' function that will be used by `morgan`
logger.stream = {
  write(message) {
    logger.info(message);
  },
};

module.exports = logger;

After copying the above code make make a folder with name logs parallel to winston or wherever you want and create a file app.log in that logs folder. Go back to config.js and set the path in the 5th line "filename: ${appRoot}/logs/app.log, " to the respective app.log created by you.

After this go to your index.js and include the following code in it.

const morgan = require('morgan');
const winston = require('./winston/config');
const express = require('express');
const app = express();
app.use(morgan('combined', { stream: winston.stream }));

winston.info('You have successfully started working with winston and morgan');

Segmentation Fault - C

Even better

#include <stdio.h>
int
main(void)
{
  char *line = NULL;
  size_t count;
  char *dup_line;

  getline(&line,&count, stdin);
  dup_line=strdup(line);

  puts(dup_line);

  free(dup_line);
  free(line);

  return 0;
}

What causes a Python segmentation fault?

I understand you've solved your issue, but for others reading this thread, here is the answer: you have to increase the stack that your operating system allocates for the python process.

The way to do it, is operating system dependant. In linux, you can check with the command ulimit -s your current value and you can increase it with ulimit -s <new_value>

Try doubling the previous value and continue doubling if it does not work, until you find one that does or run out of memory.

VBA EXCEL Multiple Nested FOR Loops that Set two variable for expression

I can't get to your google docs file at the moment but there are some issues with your code that I will try to address while answering

Sub stituterangersNEW()
Dim t As Range
Dim x As Range
Dim dify As Boolean
Dim difx As Boolean
Dim time2 As Date
Dim time1 As Date

    'You said time1 doesn't change, so I left it in a singe cell.
    'If that is not correct, you will have to play with this some more.
    time1 = Range("A6").Value

    'Looping through each of our output cells.
    For Each t In Range("B7:E9") 'Change these to match your real ranges.

        'Looping through each departure date/time.
        '(Only one row in your example. This can be adjusted if needed.)
        For Each x In Range("B2:E2") 'Change these to match your real ranges.
            'Check to see if our dep time corresponds to
            'the matching column in our output
            If t.Column = x.Column Then
                'If it does, then check to see what our time value is
                If x > 0 Then
                    time2 = x.Value
                    'Apply the change to the output cell.
                    t.Value = time1 - time2
                    'Exit out of this loop and move to the next output cell.
                    Exit For
                End If
            End If
            'If the columns don't match, or the x value is not a time
            'then we'll move to the next dep time (x)
        Next x
    Next t

End Sub

EDIT

I changed you worksheet to play with (see above for the new Sub). This probably does not suite your needs directly, but hopefully it will demonstrate the conept behind what I think you want to do. Please keep in mind that this code does not follow all the coding best preactices I would recommend (e.g. validating the time is actually a TIME and not some random other data type).

     A                      B                   C                   D                  E
1    LOAD_NUMBER            1                   2                   3                  4
2    DEPARTURE_TIME_DATE    11/12/2011 19:30    11/12/2011 19:30    11/12/2011 19:30    11/12/2011 20:00                
4    Dry_Refrig 7585.1  0   10099.8 16700
6    1/4/2012 19:30

Using the sub I got this output:

    A           B             C             D             E
7   Friday      1272:00:00    1272:00:00    1272:00:00    1271:30:00
8   Saturday    1272:00:00    1272:00:00    1272:00:00    1271:30:00
9   Thursday    1272:00:00    1272:00:00    1272:00:00    1271:30:00

Check whether a path is valid in Python without creating a file at the path's target

if os.path.exists(filePath):
    #the file is there
elif os.access(os.path.dirname(filePath), os.W_OK):
    #the file does not exists but write privileges are given
else:
    #can not write there

Note that path.exists can fail for more reasons than just the file is not there so you might have to do finer tests like testing if the containing directory exists and so on.


After my discussion with the OP it turned out, that the main problem seems to be, that the file name might contain characters that are not allowed by the filesystem. Of course they need to be removed but the OP wants to maintain as much human readablitiy as the filesystem allows.

Sadly I do not know of any good solution for this. However Cecil Curry's answer takes a closer look at detecting the problem.

How to get the file path from URI?

File myFile = new File(uri.toString());
myFile.getAbsolutePath()

should return u the correct path

EDIT

As @Tron suggested the working code is

File myFile = new File(uri.getPath());
myFile.getAbsolutePath()

Convert char* to string C++

std::string str(buffer, buffer + length);

Or, if the string already exists:

str.assign(buffer, buffer + length);

Edit: I'm still not completely sure I understand the question. But if it's something like what JoshG is suggesting, that you want up to length characters, or until a null terminator, whichever comes first, then you can use this:

std::string str(buffer, std::find(buffer, buffer + length, '\0'));

Handle JSON Decode Error when nothing returned

If you don't mind importing the json module, then the best way to handle it is through json.JSONDecodeError (or json.decoder.JSONDecodeError as they are the same) as using default errors like ValueError could catch also other exceptions not necessarily connected to the json decode one.

from json.decoder import JSONDecodeError


try:
    qByUser = byUsrUrlObj.read()
    qUserData = json.loads(qByUser).decode('utf-8')
    questionSubjs = qUserData["all"]["questions"]
except JSONDecodeError as e:
    # do whatever you want

//EDIT (Oct 2020):

As @Jacob Lee noted in the comment, there could be the basic common TypeError raised when the JSON object is not a str, bytes, or bytearray. Your question is about JSONDecodeError, but still it is worth mentioning here as a note; to handle also this situation, but differentiate between different issues, the following could be used:

from json.decoder import JSONDecodeError


try:
    qByUser = byUsrUrlObj.read()
    qUserData = json.loads(qByUser).decode('utf-8')
    questionSubjs = qUserData["all"]["questions"]
except JSONDecodeError as e:
    # do whatever you want
except TypeError as e:
    # do whatever you want in this case

How to read a text file into a string variable and strip newlines?

You can read from a file in one line:

str = open('very_Important.txt', 'r').read()

Please note that this does not close the file explicitly.

CPython will close the file when it exits as part of the garbage collection.

But other python implementations won't. To write portable code, it is better to use with or close the file explicitly. Short is not always better. See https://stackoverflow.com/a/7396043/362951

What do numbers using 0x notation mean?

It's a hexadecimal number.

0x6400 translates to 4*16^2 + 6*16^3 = 25600

Vector of structs initialization

You cannot access elements of an empty vector by subscript.
Always check that the vector is not empty & the index is valid while using the [] operator on std::vector.
[] does not add elements if none exists, but it causes an Undefined Behavior if the index is invalid.

You should create a temporary object of your structure, fill it up and then add it to the vector, using vector::push_back()

subject subObj;
subObj.name = s1;
sub.push_back(subObj);

Returning pointer from a function

To my knowledge the use of the keyword new, does relatively the same thing as malloc(sizeof identifier). The code below demonstrates how to use the keyword new.

    void main(void){
        int* test;
        test = tester();
        printf("%d",*test);
        system("pause");
    return;
}
    int* tester(void){
        int *retMe;
        retMe = new int;//<----Here retMe is getting malloc for integer type
        *retMe = 12;<---- Initializes retMe... Note * dereferences retMe 
    return retMe;
}

Core dump file is not generated

Check:

$ sysctl kernel.core_pattern

to see how your dumps are created (%e will be the process name, and %t will be the system time).

If you've Ubuntu, your dumps are created by apport in /var/crash, but in different format (edit the file to see it).

You can test it by:

sleep 10 &
killall -SIGSEGV sleep

If core dumping is successful, you will see “(core dumped)” after the segmentation fault indication.

Read more:

How to generate core dump file in Ubuntu


Ubuntu

Please read more at:

https://wiki.ubuntu.com/Apport

How to read string from keyboard using C?

When reading input from any file (stdin included) where you do not know the length, it is often better to use getline rather than scanf or fgets because getline will handle memory allocation for your string automatically so long as you provide a null pointer to receive the string entered. This example will illustrate:

#include <stdio.h>
#include <stdlib.h>

int main (int argc, char *argv[]) {

    char *line = NULL;  /* forces getline to allocate with malloc */
    size_t len = 0;     /* ignored when line = NULL */
    ssize_t read;

    printf ("\nEnter string below [ctrl + d] to quit\n");

    while ((read = getline(&line, &len, stdin)) != -1) {

        if (read > 0)
            printf ("\n  read %zd chars from stdin, allocated %zd bytes for line : %s\n", read, len, line);

        printf ("Enter string below [ctrl + d] to quit\n");
    }

    free (line);  /* free memory allocated by getline */

    return 0;
}

The relevant parts being:

char *line = NULL;  /* forces getline to allocate with malloc */
size_t len = 0;     /* ignored when line = NULL */
/* snip */
read = getline (&line, &len, stdin);

Setting line to NULL causes getline to allocate memory automatically. Example output:

$ ./getline_example

Enter string below [ctrl + d] to quit
A short string to test getline!

  read 32 chars from stdin, allocated 120 bytes for line : A short string to test getline!

Enter string below [ctrl + d] to quit
A little bit longer string to show that getline will allocated again without resetting line = NULL

  read 99 chars from stdin, allocated 120 bytes for line : A little bit longer string to show that getline will allocated again without resetting line = NULL

Enter string below [ctrl + d] to quit

So with getline you do not need to guess how long your user's string will be.

Using a custom (ttf) font in CSS

You need to use the css-property font-face to declare your font. Have a look at this fancy site: http://www.font-face.com/

Example:

@font-face {
  font-family: MyHelvetica;
  src: local("Helvetica Neue Bold"),
       local("HelveticaNeue-Bold"),
       url(MgOpenModernaBold.ttf);
  font-weight: bold;
}

See also: MDN @font-face

How can I split a string into segments of n characters?

If you didn't want to use a regular expression...

var chunks = [];

for (var i = 0, charsLength = str.length; i < charsLength; i += 3) {
    chunks.push(str.substring(i, i + 3));
}

jsFiddle.

...otherwise the regex solution is pretty good :)

Compiler error: "initializer element is not a compile-time constant"

Because you are asking the compiler to initialize a static variable with code that is inherently dynamic.

ORA-00904: invalid identifier

DEPARTMENT_CODE is not a column that exists in the table Team. Check the DDL of the table to find the proper column name.

How to list processes attached to a shared memory segment in linux?

I wrote a tool called who_attach_shm.pl, it parses /proc/[pid]/maps to get the information. you can download it from github

sample output:

shm attach process list, group by shm key
##################################################################

0x2d5feab4:    /home/curu/mem_dumper /home/curu/playd
0x4e47fc6c:    /home/curu/playd
0x77da6cfe:    /home/curu/mem_dumper /home/curu/playd /home/curu/scand

##################################################################
process shm usage
##################################################################
/home/curu/mem_dumper [2]:    0x2d5feab4 0x77da6cfe
/home/curu/playd [3]:    0x2d5feab4 0x4e47fc6c 0x77da6cfe
/home/curu/scand [1]:    0x77da6cfe

An item with the same key has already been added

I had this issue on the DBContext. Got the error when I tried run an update-database in Package Manager console to add a migration:

public virtual IDbSet Status { get; set; }

The problem was that the type and the name were the same. I changed it to:

public virtual IDbSet Statuses { get; set; }

Last segment of URL in jquery

// https://x.com/boo/?q=foo&s=bar = boo
// https://x.com/boo?q=foo&s=bar = boo
// https://x.com/boo/ = boo
// https://x.com/boo = boo

const segment = new 
URL(window.location.href).pathname.split('/').filter(Boolean).pop();
console.log(segment);

Works for me.

Controlling Maven final name of jar artifact

This works for me

mvn jar:jar -Djar.finalName=custom-jar-name

How to obtain the last path segment of a URI

is that what you are looking for:

URI uri = new URI("http://example.com/foo/bar/42?param=true");
String path = uri.getPath();
String idStr = path.substring(path.lastIndexOf('/') + 1);
int id = Integer.parseInt(idStr);

alternatively

URI uri = new URI("http://example.com/foo/bar/42?param=true");
String[] segments = uri.getPath().split("/");
String idStr = segments[segments.length-1];
int id = Integer.parseInt(idStr);

How can I check if two segments intersect?

Using OMG_Peanuts solution, I translated to SQL. (HANA Scalar Function)

Thanks OMG_Peanuts, it works great. I am using round earth, but distances are small, so I figure its okay.

FUNCTION GA_INTERSECT" ( IN LAT_A1 DOUBLE,
         IN LONG_A1 DOUBLE,
         IN LAT_A2 DOUBLE,
         IN LONG_A2 DOUBLE,
         IN LAT_B1 DOUBLE,
         IN LONG_B1 DOUBLE,
         IN LAT_B2 DOUBLE,
         IN LONG_B2 DOUBLE) 
    
RETURNS RET_DOESINTERSECT DOUBLE
    LANGUAGE SQLSCRIPT
    SQL SECURITY INVOKER AS
BEGIN

    DECLARE MA DOUBLE;
    DECLARE MB DOUBLE;
    DECLARE BA DOUBLE;
    DECLARE BB DOUBLE;
    DECLARE XA DOUBLE;
    DECLARE MAX_MIN_X DOUBLE;
    DECLARE MIN_MAX_X DOUBLE;
    DECLARE DOESINTERSECT INTEGER;
    
    SELECT 1 INTO DOESINTERSECT FROM DUMMY;
    
    IF LAT_A2-LAT_A1 != 0 AND LAT_B2-LAT_B1 != 0 THEN
        SELECT (LONG_A2 - LONG_A1)/(LAT_A2 - LAT_A1) INTO MA FROM DUMMY; 
        SELECT (LONG_B2 - LONG_B1)/(LAT_B2 - LAT_B1) INTO MB FROM DUMMY;
        IF MA = MB THEN
            SELECT 0 INTO DOESINTERSECT FROM DUMMY;
        END IF;
    END IF;
    
    SELECT LONG_A1-MA*LAT_A1 INTO BA FROM DUMMY;
    SELECT LONG_B1-MB*LAT_B1 INTO BB FROM DUMMY;
    SELECT (BB - BA) / (MA - MB) INTO XA FROM DUMMY;
    
    -- Max of Mins
    IF LAT_A1 < LAT_A2 THEN         -- MIN(LAT_A1, LAT_A2) = LAT_A1
        IF LAT_B1 < LAT_B2 THEN        -- MIN(LAT_B1, LAT_B2) = LAT_B1
            IF LAT_A1 > LAT_B1 THEN       -- MAX(LAT_A1, LAT_B1) = LAT_A1
                SELECT LAT_A1 INTO MAX_MIN_X FROM DUMMY;
            ELSE                          -- MAX(LAT_A1, LAT_B1) = LAT_B1
                SELECT LAT_B1 INTO MAX_MIN_X FROM DUMMY;
            END IF;
        ELSEIF LAT_B2 < LAT_B1 THEN   -- MIN(LAT_B1, LAT_B2) = LAT_B2
            IF LAT_A1 > LAT_B2 THEN       -- MAX(LAT_A1, LAT_B2) = LAT_A1
                SELECT LAT_A1 INTO MAX_MIN_X FROM DUMMY;
            ELSE                          -- MAX(LAT_A1, LAT_B2) = LAT_B2
                SELECT LAT_B2 INTO MAX_MIN_X FROM DUMMY;
            END IF;
        END IF;
    ELSEIF LAT_A2 < LAT_A1 THEN     -- MIN(LAT_A1, LAT_A2) = LAT_A2
        IF LAT_B1 < LAT_B2 THEN        -- MIN(LAT_B1, LAT_B2) = LAT_B1
            IF LAT_A2 > LAT_B1 THEN       -- MAX(LAT_A2, LAT_B1) = LAT_A2
                SELECT LAT_A2 INTO MAX_MIN_X FROM DUMMY;
            ELSE                          -- MAX(LAT_A2, LAT_B1) = LAT_B1
                SELECT LAT_B1 INTO MAX_MIN_X FROM DUMMY;
            END IF;
        ELSEIF LAT_B2 < LAT_B1 THEN   -- MIN(LAT_B1, LAT_B2) = LAT_B2
            IF LAT_A2 > LAT_B2 THEN       -- MAX(LAT_A2, LAT_B2) = LAT_A2
                SELECT LAT_A2 INTO MAX_MIN_X FROM DUMMY;
            ELSE                          -- MAX(LAT_A2, LAT_B2) = LAT_B2
                SELECT LAT_B2 INTO MAX_MIN_X FROM DUMMY;
            END IF;
        END IF;
    END IF;
    
    -- Min of Max
    IF LAT_A1 > LAT_A2 THEN         -- MAX(LAT_A1, LAT_A2) = LAT_A1
        IF LAT_B1 > LAT_B2 THEN        -- MAX(LAT_B1, LAT_B2) = LAT_B1
            IF LAT_A1 < LAT_B1 THEN       -- MIN(LAT_A1, LAT_B1) = LAT_A1
                SELECT LAT_A1 INTO MIN_MAX_X FROM DUMMY;
            ELSE                          -- MIN(LAT_A1, LAT_B1) = LAT_B1
                SELECT LAT_B1 INTO MIN_MAX_X FROM DUMMY;
            END IF;
        ELSEIF LAT_B2 > LAT_B1 THEN   -- MAX(LAT_B1, LAT_B2) = LAT_B2
            IF LAT_A1 < LAT_B2 THEN       -- MIN(LAT_A1, LAT_B2) = LAT_A1
                SELECT LAT_A1 INTO MIN_MAX_X FROM DUMMY;
            ELSE                          -- MIN(LAT_A1, LAT_B2) = LAT_B2
                SELECT LAT_B2 INTO MIN_MAX_X FROM DUMMY;
            END IF;
        END IF;
    ELSEIF LAT_A2 > LAT_A1 THEN     -- MAX(LAT_A1, LAT_A2) = LAT_A2
        IF LAT_B1 > LAT_B2 THEN        -- MAX(LAT_B1, LAT_B2) = LAT_B1
            IF LAT_A2 < LAT_B1 THEN       -- MIN(LAT_A2, LAT_B1) = LAT_A2
                SELECT LAT_A2 INTO MIN_MAX_X FROM DUMMY;
            ELSE                          -- MIN(LAT_A2, LAT_B1) = LAT_B1
                SELECT LAT_B1 INTO MIN_MAX_X FROM DUMMY;
            END IF;
        ELSEIF LAT_B2 > LAT_B1 THEN   -- MAX(LAT_B1, LAT_B2) = LAT_B2
            IF LAT_A2 < LAT_B2 THEN       -- MIN(LAT_A2, LAT_B2) = LAT_A2
                SELECT LAT_A2 INTO MIN_MAX_X FROM DUMMY;
            ELSE                          -- MIN(LAT_A2, LAT_B2) = LAT_B2
                SELECT LAT_B2 INTO MIN_MAX_X FROM DUMMY;
            END IF;
        END IF;
    END IF;
        
    
    IF XA < MAX_MIN_X OR
       XA > MIN_MAX_X THEN  
       SELECT 0 INTO DOESINTERSECT FROM DUMMY;
    END IF;
    
    RET_DOESINTERSECT := :DOESINTERSECT;
END;

Fixing Segmentation faults in C++

I don't know of any methodology to use to fix things like this. I don't think it would be possible to come up with one either for the very issue at hand is that your program's behavior is undefined (I don't know of any case when SEGFAULT hasn't been caused by some sort of UB).

There are all kinds of "methodologies" to avoid the issue before it arises. One important one is RAII.

Besides that, you just have to throw your best psychic energies at it.

Object of class stdClass could not be converted to string

In General to get rid of

Object of class stdClass could not be converted to string.

try to use echo '<pre>'; print_r($sql_query); for my SQL Query got the result as

stdClass Object
(
    [num_rows] => 1
    [row] => Array
        (
            [option_id] => 2
            [type] => select
            [sort_order] => 0
        )

    [rows] => Array
        (
            [0] => Array
                (
                    [option_id] => 2
                    [type] => select
                    [sort_order] => 0
                )

        )

)

In order to acces there are different methods E.g.: num_rows, row, rows

echo $query2->row['option_id'];

Will give the result as 2

How to set up a cron job to run an executable every hour?

If you're using Ubuntu, you can put a shell script in one of these folders: /etc/cron.daily, /etc/cron.hourly, /etc/cron.monthly or /etc/cron.weekly.

For more detail, check out this post: https://askubuntu.com/questions/2368/how-do-i-set-up-a-cron-job

Set Colorbar Range in matplotlib

Use the CLIM function (equivalent to CAXIS function in MATLAB):

plt.pcolor(X, Y, v, cmap=cm)
plt.clim(-4,4)  # identical to caxis([-4,4]) in MATLAB
plt.show()

Downloading a picture via urllib and python

If you need proxy support you can do this:

  if needProxy == False:
    returnCode, urlReturnResponse = urllib.urlretrieve( myUrl, fullJpegPathAndName )
  else:
    proxy_support = urllib2.ProxyHandler({"https":myHttpProxyAddress})
    opener = urllib2.build_opener(proxy_support)
    urllib2.install_opener(opener)
    urlReader = urllib2.urlopen( myUrl ).read() 
    with open( fullJpegPathAndName, "w" ) as f:
      f.write( urlReader )

LINQ Joining in C# with multiple conditions

If you need not equal object condition use cross join sequences:

var query = from obj1 in set1
from obj2 in set2
where obj1.key1 == obj2.key2 && obj1.key3.contains(obj2.key5) [...conditions...]

Determine the line of code that causes a segmentation fault?

Also, you can give valgrind a try: if you install valgrind and run

valgrind --leak-check=full <program>

then it will run your program and display stack traces for any segfaults, as well as any invalid memory reads or writes and memory leaks. It's really quite useful.

How can I time a code segment for testing performance with Pythons timeit?

Quite apart from the timing, this code you show is simply incorrect: you execute 100 connections (completely ignoring all but the last one), and then when you do the first execute call you pass it a local variable query_stmt which you only initialize after the execute call.

First, make your code correct, without worrying about timing yet: i.e. a function that makes or receives a connection and performs 100 or 500 or whatever number of updates on that connection, then closes the connection. Once you have your code working correctly is the correct point at which to think about using timeit on it!

Specifically, if the function you want to time is a parameter-less one called foobar you can use timeit.timeit (2.6 or later -- it's more complicated in 2.5 and before):

timeit.timeit('foobar()', number=1000)

You'd better specify the number of runs because the default, a million, may be high for your use case (leading to spending a lot of time in this code;-).

"No such file or directory" error when executing a binary

readelf -a xxx

 INTERP         
  0x0000000000000238 0x0000000000400238 0x0000000000400238           
  0x000000000000001c 0x000000000000001c  R      1
  [Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]

How to catch segmentation fault in Linux?

Sometimes we want to catch a SIGSEGV to find out if a pointer is valid, that is, if it references a valid memory address. (Or even check if some arbitrary value may be a pointer.)

One option is to check it with isValidPtr() (worked on Android):

int isValidPtr(const void*p, int len) {
    if (!p) {
    return 0;
    }
    int ret = 1;
    int nullfd = open("/dev/random", O_WRONLY);
    if (write(nullfd, p, len) < 0) {
    ret = 0;
    /* Not OK */
    }
    close(nullfd);
    return ret;
}
int isValidOrNullPtr(const void*p, int len) {
    return !p||isValidPtr(p, len);
}

Another option is to read the memory protection attributes, which is a bit more tricky (worked on Android):

re_mprot.c:

#include <errno.h>
#include <malloc.h>
//#define PAGE_SIZE 4096
#include "dlog.h"
#include "stdlib.h"
#include "re_mprot.h"

struct buffer {
    int pos;
    int size;
    char* mem;
};

char* _buf_reset(struct buffer*b) {
    b->mem[b->pos] = 0;
    b->pos = 0;
    return b->mem;
}

struct buffer* _new_buffer(int length) {
    struct buffer* res = malloc(sizeof(struct buffer)+length+4);
    res->pos = 0;
    res->size = length;
    res->mem = (void*)(res+1);
    return res;
}

int _buf_putchar(struct buffer*b, int c) {
    b->mem[b->pos++] = c;
    return b->pos >= b->size;
}

void show_mappings(void)
{
    DLOG("-----------------------------------------------\n");
    int a;
    FILE *f = fopen("/proc/self/maps", "r");
    struct buffer* b = _new_buffer(1024);
    while ((a = fgetc(f)) >= 0) {
    if (_buf_putchar(b,a) || a == '\n') {
        DLOG("/proc/self/maps: %s",_buf_reset(b));
    }
    }
    if (b->pos) {
    DLOG("/proc/self/maps: %s",_buf_reset(b));
    }
    free(b);
    fclose(f);
    DLOG("-----------------------------------------------\n");
}

unsigned int read_mprotection(void* addr) {
    int a;
    unsigned int res = MPROT_0;
    FILE *f = fopen("/proc/self/maps", "r");
    struct buffer* b = _new_buffer(1024);
    while ((a = fgetc(f)) >= 0) {
    if (_buf_putchar(b,a) || a == '\n') {
        char*end0 = (void*)0;
        unsigned long addr0 = strtoul(b->mem, &end0, 0x10);
        char*end1 = (void*)0;
        unsigned long addr1 = strtoul(end0+1, &end1, 0x10);
        if ((void*)addr0 < addr && addr < (void*)addr1) {
            res |= (end1+1)[0] == 'r' ? MPROT_R : 0;
            res |= (end1+1)[1] == 'w' ? MPROT_W : 0;
            res |= (end1+1)[2] == 'x' ? MPROT_X : 0;
            res |= (end1+1)[3] == 'p' ? MPROT_P
                 : (end1+1)[3] == 's' ? MPROT_S : 0;
            break;
        }
        _buf_reset(b);
    }
    }
    free(b);
    fclose(f);
    return res;
}

int has_mprotection(void* addr, unsigned int prot, unsigned int prot_mask) {
    unsigned prot1 = read_mprotection(addr);
    return (prot1 & prot_mask) == prot;
}

char* _mprot_tostring_(char*buf, unsigned int prot) {
    buf[0] = prot & MPROT_R ? 'r' : '-';
    buf[1] = prot & MPROT_W ? 'w' : '-';
    buf[2] = prot & MPROT_X ? 'x' : '-';
    buf[3] = prot & MPROT_S ? 's' : prot & MPROT_P ? 'p' :  '-';
    buf[4] = 0;
    return buf;
}

re_mprot.h:

#include <alloca.h>
#include "re_bits.h"
#include <sys/mman.h>

void show_mappings(void);

enum {
    MPROT_0 = 0, // not found at all
    MPROT_R = PROT_READ,                                 // readable
    MPROT_W = PROT_WRITE,                                // writable
    MPROT_X = PROT_EXEC,                                 // executable
    MPROT_S = FIRST_UNUSED_BIT(MPROT_R|MPROT_W|MPROT_X), // shared
    MPROT_P = MPROT_S<<1,                                // private
};

// returns a non-zero value if the address is mapped (because either MPROT_P or MPROT_S will be set for valid addresses)
unsigned int read_mprotection(void* addr);

// check memory protection against the mask
// returns true if all bits corresponding to non-zero bits in the mask
// are the same in prot and read_mprotection(addr)
int has_mprotection(void* addr, unsigned int prot, unsigned int prot_mask);

// convert the protection mask into a string. Uses alloca(), no need to free() the memory!
#define mprot_tostring(x) ( _mprot_tostring_( (char*)alloca(8) , (x) ) )
char* _mprot_tostring_(char*buf, unsigned int prot);

PS DLOG() is printf() to the Android log. FIRST_UNUSED_BIT() is defined here.

PPS It may not be a good idea to call alloca() in a loop -- the memory may be not freed until the function returns.

What is a segmentation fault?

Wikipedia's Segmentation_fault page has a very nice description about it, just pointing out the causes and reasons. Have a look into the wiki for a detailed description.

In computing, a segmentation fault (often shortened to segfault) or access violation is a fault raised by hardware with memory protection, notifying an operating system (OS) about a memory access violation.

The following are some typical causes of a segmentation fault:

  • Dereferencing NULL pointers – this is special-cased by memory management hardware
  • Attempting to access a nonexistent memory address (outside process's address space)
  • Attempting to access memory the program does not have rights to (such as kernel structures in process context)
  • Attempting to write read-only memory (such as code segment)

These in turn are often caused by programming errors that result in invalid memory access:

  • Dereferencing or assigning to an uninitialized pointer (wild pointer, which points to a random memory address)

  • Dereferencing or assigning to a freed pointer (dangling pointer, which points to memory that has been freed/deallocated/deleted)

  • A buffer overflow.

  • A stack overflow.

  • Attempting to execute a program that does not compile correctly. (Some compilers will output an executable file despite the presence of compile-time errors.)

Change font size of UISegmentedControl

Use the Appearance API in iOS 5.0+:

[[UISegmentedControl appearance] setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:[UIFont fontWithName:@"STHeitiSC-Medium" size:13.0], UITextAttributeFont, nil] forState:UIControlStateNormal];

Links: http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIAppearance_Protocol/Reference/Reference.html#//apple_ref/doc/uid/TP40010906

http://www.raywenderlich.com/4344/user-interface-customization-in-ios-5

Segmentation fault on large array sizes

Also, if you are running in most UNIX & Linux systems you can temporarily increase the stack size by the following command:

ulimit -s unlimited

But be careful, memory is a limited resource and with great power come great responsibilities :)

What resources are shared between threads?

Threads share everything [1]. There is one address space for the whole process.

Each thread has its own stack and registers, but all threads' stacks are visible in the shared address space.

If one thread allocates some object on its stack, and sends the address to another thread, they'll both have equal access to that object.


Actually, I just noticed a broader issue: I think you're confusing two uses of the word segment.

The file format for an executable (eg, ELF) has distinct sections in it, which may be referred to as segments, containing compiled code (text), initialized data, linker symbols, debug info, etc. There are no heap or stack segments here, since those are runtime-only constructs.

These binary file segments may be mapped into the process address space seperately, with different permissions (eg, read-only executable for code/text, and copy-on-write non-executable for initialized data).

Areas of this address space are used for different purposes, like heap allocation and thread stacks, by convention (enforced by your language runtime libraries). It is all just memory though, and probably not segmented unless you're running in virtual 8086 mode. Each thread's stack is a chunk of memory allocated at thread creation time, with the current stack top address stored in a stack pointer register, and each thread keeps its own stack pointer along with its other registers.


[1] OK, I know: signal masks, TSS/TSD etc. The address space, including all its mapped program segments, are still shared though.

Spring schemaLocation fails when there is no internet connection

If you are using eclipse for your development , it helps if you install STS plugin for Eclipse [ from the marketPlace for the specific version of eclipse .

Now When you try to create a new configuration file in a folder(normally resources) inside the project , the options would have a "Spring Folder" and you can choose a "Spring Bean Definition File " option Spring > Spring Bean Configuation File .

With this option selected , when you follow steps , it asks you to select for namespaces and the specific versions :

And so the possibility of having a non-existent jar Or old version can be eliminated .

Would have posted images as well , but my reputation is pretty low.. :(

maven compilation failure

If your dependencies are fine (check with mvn dependency:list) like mine were, then it's a maven glitch, if you're using Eclipse do:

  1. Right click the project > Maven > Update Project...
  2. Check everything but Offline
  3. OK

You should be good.

I don't know the equivalent mvn commands, if anyone could post them they could be useful.

What causes a SIGSEGV

There are various causes of segmentation faults, but fundamentally, you are accessing memory incorrectly. This could be caused by dereferencing a null pointer, or by trying to modify readonly memory, or by using a pointer to somewhere that is not mapped into the memory space of your process (that probably means you are trying to use a number as a pointer, or you incremented a pointer too far). On some machines, it is possible for a misaligned access via a pointer to cause the problem too - if you have an odd address and try to read an even number of bytes from it, for example (that can generate SIGBUS, instead).

Recursive Fibonacci

if(n==1 || n==0){
    return n;
}else{     
    return fib(n-1) + fib(n-2);
}

However, using recursion to get fibonacci number is bad practice, because function is called about 8.5 times than received number. E.g. to get fibonacci number of 30 (1346269) - function is called 7049122 times!

Understanding Linux /proc/id/maps

Please check: http://man7.org/linux/man-pages/man5/proc.5.html

address           perms offset  dev   inode       pathname
00400000-00452000 r-xp 00000000 08:02 173521      /usr/bin/dbus-daemon

The address field is the address space in the process that the mapping occupies.

The perms field is a set of permissions:

 r = read
 w = write
 x = execute
 s = shared
 p = private (copy on write)

The offset field is the offset into the file/whatever;

dev is the device (major:minor);

inode is the inode on that device.0 indicates that no inode is associated with the memoryregion, as would be the case with BSS (uninitialized data).

The pathname field will usually be the file that is backing the mapping. For ELF files, you can easily coordinate with the offset field by looking at the Offset field in the ELF program headers (readelf -l).

Under Linux 2.0, there is no field giving pathname.

How do I calculate the normal vector of a line segment?

If we define dx = x2 - x1 and dy = y2 - y1, then the normals are (-dy, dx) and (dy, -dx).

Note that no division is required, and so you're not risking dividing by zero.

Accessing an array out of bounds gives no error, why?

Run this through Valgrind and you might see an error.

As Falaina pointed out, valgrind does not detect many instances of stack corruption. I just tried the sample under valgrind, and it does indeed report zero errors. However, Valgrind can be instrumental in finding many other types of memory problems, it's just not particularly useful in this case unless you modify your bulid to include the --stack-check option. If you build and run the sample as

g++ --stack-check -W -Wall errorRange.cpp -o errorRange
valgrind ./errorRange

valgrind will report an error.

Are there any standard exit status codes in Linux?

Part 1: Advanced Bash Scripting Guide

As always, the Advanced Bash Scripting Guide has great information: (This was linked in another answer, but to a non-canonical URL.)

1: Catchall for general errors
2: Misuse of shell builtins (according to Bash documentation)
126: Command invoked cannot execute
127: "command not found"
128: Invalid argument to exit
128+n: Fatal error signal "n"
255: Exit status out of range (exit takes only integer args in the range 0 - 255)

Part 2: sysexits.h

The ABSG references sysexits.h.

On Linux:

$ find /usr -name sysexits.h
/usr/include/sysexits.h
$ cat /usr/include/sysexits.h

/*
 * Copyright (c) 1987, 1993
 *  The Regents of the University of California.  All rights reserved.

 (A whole bunch of text left out.)

#define EX_OK           0       /* successful termination */
#define EX__BASE        64      /* base value for error messages */
#define EX_USAGE        64      /* command line usage error */
#define EX_DATAERR      65      /* data format error */
#define EX_NOINPUT      66      /* cannot open input */    
#define EX_NOUSER       67      /* addressee unknown */    
#define EX_NOHOST       68      /* host name unknown */
#define EX_UNAVAILABLE  69      /* service unavailable */
#define EX_SOFTWARE     70      /* internal software error */
#define EX_OSERR        71      /* system error (e.g., can't fork) */
#define EX_OSFILE       72      /* critical OS file missing */
#define EX_CANTCREAT    73      /* can't create (user) output file */
#define EX_IOERR        74      /* input/output error */
#define EX_TEMPFAIL     75      /* temp failure; user is invited to retry */
#define EX_PROTOCOL     76      /* remote error in protocol */
#define EX_NOPERM       77      /* permission denied */
#define EX_CONFIG       78      /* configuration error */

#define EX__MAX 78      /* maximum listed value */

Grab a segment of an array in Java without creating a new array on heap

One option would be to pass the whole array and the start and end indices, and iterate between those instead of iterating over the whole array passed.

void method1(byte[] array) {
    method2(array,4,5);
}
void method2(byte[] smallarray,int start,int end) {
    for ( int i = start; i <= end; i++ ) {
        ....
    }
}

Circle line-segment collision detection algorithm?

I know it's been a while since this thread was open. From the answer given by chmike and improved by Aqib Mumtaz. They give a good answer but only works for a infinite line as said Aqib. So I add some comparisons to know if the line segment touch the circle, I write it in Python.

def LineIntersectCircle(c, r, p1, p2):
    #p1 is the first line point
    #p2 is the second line point
    #c is the circle's center
    #r is the circle's radius

    p3 = [p1[0]-c[0], p1[1]-c[1]]
    p4 = [p2[0]-c[0], p2[1]-c[1]]

    m = (p4[1] - p3[1]) / (p4[0] - p3[0])
    b = p3[1] - m * p3[0]

    underRadical = math.pow(r,2)*math.pow(m,2) + math.pow(r,2) - math.pow(b,2)

    if (underRadical < 0):
        print("NOT")
    else:
        t1 = (-2*m*b+2*math.sqrt(underRadical)) / (2 * math.pow(m,2) + 2)
        t2 = (-2*m*b-2*math.sqrt(underRadical)) / (2 * math.pow(m,2) + 2)
        i1 = [t1+c[0], m * t1 + b + c[1]]
        i2 = [t2+c[0], m * t2 + b + c[1]]

        if p1[0] > p2[0]:                                           #Si el punto 1 es mayor al 2 en X
            if (i1[0] < p1[0]) and (i1[0] > p2[0]):                 #Si el punto iX esta entre 2 y 1 en X
                if p1[1] > p2[1]:                                   #Si el punto 1 es mayor al 2 en Y
                    if (i1[1] < p1[1]) and (i1[1] > p2[1]):         #Si el punto iy esta entre 2 y 1
                        print("Intersection")
                if p1[1] < p2[1]:                                   #Si el punto 2 es mayo al 2 en Y
                    if (i1[1] > p1[1]) and (i1[1] < p2[1]):         #Si el punto iy esta entre 1 y 2
                        print("Intersection")

        if p1[0] < p2[0]:                                           #Si el punto 2 es mayor al 1 en X
            if (i1[0] > p1[0]) and (i1[0] < p2[0]):                 #Si el punto iX esta entre 1 y 2 en X
                if p1[1] > p2[1]:                                   #Si el punto 1 es mayor al 2 en Y
                    if (i1[1] < p1[1]) and (i1[1] > p2[1]):         #Si el punto iy esta entre 2 y 1
                        print("Intersection")
                if p1[1] < p2[1]:                                   #Si el punto 2 es mayo al 2 en Y
                    if (i1[1] > p1[1]) and (i1[1] < p2[1]):         #Si el punto iy esta entre 1 y 2
                        print("Intersection")

        if p1[0] > p2[0]:                                           #Si el punto 1 es mayor al 2 en X
            if (i2[0] < p1[0]) and (i2[0] > p2[0]):                 #Si el punto iX esta entre 2 y 1 en X
                if p1[1] > p2[1]:                                   #Si el punto 1 es mayor al 2 en Y
                    if (i2[1] < p1[1]) and (i2[1] > p2[1]):         #Si el punto iy esta entre 2 y 1
                        print("Intersection")
                if p1[1] < p2[1]:                                   #Si el punto 2 es mayo al 2 en Y
                    if (i2[1] > p1[1]) and (i2[1] < p2[1]):         #Si el punto iy esta entre 1 y 2
                        print("Intersection")

        if p1[0] < p2[0]:                                           #Si el punto 2 es mayor al 1 en X
            if (i2[0] > p1[0]) and (i2[0] < p2[0]):                 #Si el punto iX esta entre 1 y 2 en X
                if p1[1] > p2[1]:                                   #Si el punto 1 es mayor al 2 en Y
                    if (i2[1] < p1[1]) and (i2[1] > p2[1]):         #Si el punto iy esta entre 2 y 1
                        print("Intersection")
                if p1[1] < p2[1]:                                   #Si el punto 2 es mayo al 2 en Y
                    if (i2[1] > p1[1]) and (i2[1] < p2[1]):         #Si el punto iy esta entre 1 y 2
                        print("Intersection")

Is it possible to modify a string of char in C?

A lot of folks get confused about the difference between char* and char[] in conjunction with string literals in C. When you write:

char *foo = "hello world";

...you are actually pointing foo to a constant block of memory (in fact, what the compiler does with "hello world" in this instance is implementation-dependent.)

Using char[] instead tells the compiler that you want to create an array and fill it with the contents, "hello world". foo is the a pointer to the first index of the char array. They both are char pointers, but only char[] will point to a locally allocated and mutable block of memory.

Shortest distance between a point and a line segment

I've made an interactive Desmos graph to demonstrate how to achieve this:

https://www.desmos.com/calculator/kswrm8ddum

The red point is A, the green point is B, and the point C is blue. You can drag the points in the graph to see the values change. On the left, the value 's' is the parameter of the line segment (i.e. s = 0 means the point A, and s = 1 means the point B). The value 'd' is the distance from the third point to the line through A and B.

EDIT:

Fun little insight: the coordinate (s, d) is the coordinate of the third point C in the coordinate system where AB is the unit x-axis, and the unit y-axis is perpendicular to AB.

Search and replace part of string in database

I would consider writing a CLR replace function with RegEx support for this kind of string manipulation.

How do you detect where two line segments intersect?

FWIW, the following function (in C) both detects line intersections and determines the intersection point. It is based on an algorithm in Andre LeMothe's "Tricks of the Windows Game Programming Gurus". It's not dissimilar to some of the algorithm's in other answers (e.g. Gareth's). LeMothe then uses Cramer's Rule (don't ask me) to solve the equations themselves.

I can attest that it works in my feeble asteroids clone, and seems to deal correctly with the edge cases described in other answers by Elemental, Dan and Wodzu. It's also probably faster than the code posted by KingNestor because it's all multiplication and division, no square roots!

I guess there's some potential for divide by zero in there, though it hasn't been an issue in my case. Easy enough to modify to avoid the crash anyway.

// Returns 1 if the lines intersect, otherwise 0. In addition, if the lines 
// intersect the intersection point may be stored in the floats i_x and i_y.
char get_line_intersection(float p0_x, float p0_y, float p1_x, float p1_y, 
    float p2_x, float p2_y, float p3_x, float p3_y, float *i_x, float *i_y)
{
    float s1_x, s1_y, s2_x, s2_y;
    s1_x = p1_x - p0_x;     s1_y = p1_y - p0_y;
    s2_x = p3_x - p2_x;     s2_y = p3_y - p2_y;

    float s, t;
    s = (-s1_y * (p0_x - p2_x) + s1_x * (p0_y - p2_y)) / (-s2_x * s1_y + s1_x * s2_y);
    t = ( s2_x * (p0_y - p2_y) - s2_y * (p0_x - p2_x)) / (-s2_x * s1_y + s1_x * s2_y);

    if (s >= 0 && s <= 1 && t >= 0 && t <= 1)
    {
        // Collision detected
        if (i_x != NULL)
            *i_x = p0_x + (t * s1_x);
        if (i_y != NULL)
            *i_y = p0_y + (t * s1_y);
        return 1;
    }

    return 0; // No collision
}

BTW, I must say that in LeMothe's book, though he apparently gets the algorithm right, the concrete example he shows plugs in the wrong numbers and does calculations wrong. For example:

(4 * (4 - 1) + 12 * (7 - 1)) / (17 * 4 + 12 * 10)

= 844/0.88

= 0.44

That confused me for hours. :(

How can you determine a point is between two other points on a line segment?

Here's how I did it at school. I forgot why it is not a good idea.

EDIT:

@Darius Bacon: cites a "Beautiful Code" book which contains an explanation why the belowed code is not a good idea.

#!/usr/bin/env python
from __future__ import division

epsilon = 1e-6

class Point:
    def __init__(self, x, y):
        self.x, self.y = x, y

class LineSegment:
    """
    >>> ls = LineSegment(Point(0,0), Point(2,4))
    >>> Point(1, 2) in ls
    True
    >>> Point(.5, 1) in ls
    True
    >>> Point(.5, 1.1) in ls
    False
    >>> Point(-1, -2) in ls
    False
    >>> Point(.1, 0.20000001) in ls
    True
    >>> Point(.1, 0.2001) in ls
    False
    >>> ls = LineSegment(Point(1, 1), Point(3, 5))
    >>> Point(2, 3) in ls
    True
    >>> Point(1.5, 2) in ls
    True
    >>> Point(0, -1) in ls
    False
    >>> ls = LineSegment(Point(1, 2), Point(1, 10))
    >>> Point(1, 6) in ls
    True
    >>> Point(1, 1) in ls
    False
    >>> Point(2, 6) in ls 
    False
    >>> ls = LineSegment(Point(-1, 10), Point(5, 10))
    >>> Point(3, 10) in ls
    True
    >>> Point(6, 10) in ls
    False
    >>> Point(5, 10) in ls
    True
    >>> Point(3, 11) in ls
    False
    """
    def __init__(self, a, b):
        if a.x > b.x:
            a, b = b, a
        (self.x0, self.y0, self.x1, self.y1) = (a.x, a.y, b.x, b.y)
        self.slope = (self.y1 - self.y0) / (self.x1 - self.x0) if self.x1 != self.x0 else None

    def __contains__(self, c):
        return (self.x0 <= c.x <= self.x1 and
                min(self.y0, self.y1) <= c.y <= max(self.y0, self.y1) and
                (not self.slope or -epsilon < (c.y - self.y(c.x)) < epsilon))

    def y(self, x):        
        return self.slope * (x - self.x0) + self.y0

if __name__ == '__main__':
    import  doctest
    doctest.testmod()

How do I concatenate const/literal strings in C?

Do not forget to initialize the output buffer. The first argument to strcat must be a null terminated string with enough extra space allocated for the resulting string:

char out[1024] = ""; // must be initialized
strcat( out, null_terminated_string ); 
// null_terminated_string has less than 1023 chars

Using mysql concat() in WHERE clause?

What you have should work but can be reduced to:

select * from table where concat_ws(' ',first_name,last_name) 
like '%$search_term%';

Can you provide an example name and search term where this doesn't work?

What can I use for good quality code coverage for C#/.NET?

An alternative to NCover can be PartCover, is an open source code coverage tool for .NET very similar to NCover, it includes a console application, a GUI coverage browser, and XSL transforms for use in CruiseControl.NET.

It is a very interesting product.

OpenCover has replaced PartCover.

What is the meaning of the term "thread-safe"?

Yes and yes. It implies that data is not modified by more than one thread simultaneously. However, your program might work as expected, and appear thread-safe, even if it is fundamentally not.

Note that the unpredictablility of results is a consequence of 'race-conditions' that probably result in data being modified in an order other than the expected one.

Where are static variables stored in C and C++?

Well this question is bit too old, but since nobody points out any useful information: Check the post by 'mohit12379' explaining the store of static variables with same name in the symbol table: http://www.geekinterview.com/question_details/24745

How to generate a core dump in Linux on a segmentation fault?

Better to turn on core dump programmatically using system call setrlimit.

example:

#include <sys/resource.h>

bool enable_core_dump(){    
    struct rlimit corelim;

    corelim.rlim_cur = RLIM_INFINITY;
    corelim.rlim_max = RLIM_INFINITY;

    return (0 == setrlimit(RLIMIT_CORE, &corelim));
}

LINQ-to-SQL vs stored procedures?

All these answers leaning towards LINQ are mainly talking about EASE of DEVELOPMENT which is more or less connected to poor quality of coding or laziness in coding. I am like that only.

Some advantages or Linq, I read here as , easy to test, easy to debug etc, but these are no where connected to Final output or end user. This is always going cause the trouble the end user on performance. Whats the point loading many things in memory and then applying filters on in using LINQ?

Again TypeSafety, is caution that "we are careful to avoid wrong typecasting" which again poor quality we are trying to improve by using linq. Even in that case, if anything in database changes, e.g. size of String column, then linq needs to be re-compiled and would not be typesafe without that .. I tried.

Although, we found is good, sweet, interesting etc while working with LINQ, it has shear disadvantage of making developer lazy :) and it is proved 1000 times that it is bad (may be worst) on performance compared to Stored Procs.

Stop being lazy. I am trying hard. :)

Binding a generic list to a repeater - ASP.NET

It is surprisingly simple...

Code behind:

// Here's your object that you'll create a list of
private class Products
{
    public string ProductName { get; set; }
    public string ProductDescription { get; set; }
    public string ProductPrice { get; set; }
}

// Here you pass in the List of Products
private void BindItemsInCart(List<Products> ListOfSelectedProducts)
{   
    // The the LIST as the DataSource
    this.rptItemsInCart.DataSource = ListOfSelectedProducts;

    // Then bind the repeater
    // The public properties become the columns of your repeater
    this.rptItemsInCart.DataBind();
}

ASPX code:

<asp:Repeater ID="rptItemsInCart" runat="server">
  <HeaderTemplate>
    <table>
      <thead>
        <tr>
            <th>Product Name</th>
            <th>Product Description</th>
            <th>Product Price</th>
        </tr>
      </thead>
      <tbody>
  </HeaderTemplate>
  <ItemTemplate>
    <tr>
      <td><%# Eval("ProductName") %></td>
      <td><%# Eval("ProductDescription")%></td>
      <td><%# Eval("ProductPrice")%></td>
    </tr>
  </ItemTemplate>
  <FooterTemplate>
    </tbody>
    </table>
  </FooterTemplate>
</asp:Repeater>

I hope this helps!

Can't update data-attribute value

Had similar problem and in the end I had to set both

obj.attr('data-myvar','myval')

and

obj.data('myvar','myval')

And after this

obj.data('myvar') == obj.attr('data-myvar')

Hope this helps.

Static Final Variable in Java

For the primitive types, the 'final static' will be a proper declaration to declare a constant. A non-static final variable makes sense when it is a constant reference to an object. In this case each instance can contain its own reference, as shown in JLS 4.5.4.

See Pavel's response for the correct answer.

How could I create a function with a completion handler in Swift?

Swift 5.0 + , Simple and Short

example:

Style 1

    func methodName(completionBlock: () -> Void)  {

          print("block_Completion")
          completionBlock()
    }

Style 2

    func methodName(completionBlock: () -> ())  {

        print("block_Completion")
        completionBlock()
    }

Use:

    override func viewDidLoad() {
        super.viewDidLoad()
        
        methodName {

            print("Doing something after Block_Completion!!")
        }
    }

Output

block_Completion

Doing something after Block_Completion!!

How to get current value of RxJS Subject or Observable?

I had similar situation where late subscribers subscribe to the Subject after its value arrived.

I found ReplaySubject which is similar to BehaviorSubject works like a charm in this case. And here is a link to better explanation: http://reactivex.io/rxjs/manual/overview.html#replaysubject

Docker can't connect to docker daemon

I also got the issue "Cannot connect to the Docker daemon. Is the docker daemon running on this host?".

I had forgot to use sudo. Hope it will help some of us.

$:docker images
Cannot connect to the Docker daemon. Is the docker daemon running on this host?

$:sudo docker images
REPOSITORY   TAG   IMAGE ID   CREATED   SIZE

MySQL, Check if a column exists in a table with SQL

Select just column_name from information schema and put the result of this query into variable. Then test the variable to decide if table needs alteration or not.

P.S. Don't foget to specify TABLE_SCHEMA for COLUMNS table as well.

SSIS Excel Connection Manager failed to Connect to the Source

After researching everywhere finally i have found out temporary solution. Because i have try all the solution installing access drivers but still i am facing same issues.

For excel source, Before this step you need to change the setting. Save excel file as 2010 format.xlsx

Also set Project Configuration Properties for Debugging Run64BitRuntime = False

  1. Drag and drop the excel source
  2. Double click on the excel source and connect excel. Any way you will get an same error no table or view cannot load....
  3. Click ok
  4. Right click on excel source, click on show advanced edit.
  5. In that click on component properties.
  6. You can see openrowset. In that right side you need to enter you excel sheet name example: if in excel sheet1 then you need to enter sheet1$. I.e end with dollar symbol. And click ok.
  7. Now you can do other works connecting to destination.

I am using visual studio 2017, sql server 2017, office 2016, and Microsoft access database 2010 engine 32bit. Os windows 10 64 bit.

This is temporary solution. Because many peoples are searching for this type of question. Finally I figured out and this solution is not available in any of the website.

Streaming Audio from A URL in Android using MediaPlayer?

I've had the same error as you have and it turned out that there was nothing wrong with the code. The problem was that the webserver was sending the wrong Content-Type header.

Try wireshark or something similar to see what content-type the webserver is sending.

Export table data from one SQL Server to another

Try using the SQL Server Import and Export Wizard (under Tasks -> Export Data).

It offers to create the tables in the destination database. Whereas, as you've seen, the scripting wizard can only create the table structure.

How can I declare dynamic String array in Java

What your looking for is the DefaultListModel - Dynamic String List Variable.

Here is a whole class that uses the DefaultListModel as though it were the TStringList of Delphi. The difference is that you can add Strings to the list without limitation and you have the same ability at getting a single entry by specifying the entry int.

FileName: StringList.java

package YOUR_PACKAGE_GOES_HERE;

//This is the StringList Class by i2programmer
//You may delete these comments
//This code is offered freely at no requirements
//You may alter the code as you wish
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.DefaultListModel;

public class StringList {

    public static String OutputAsString(DefaultListModel list, int entry) {
        return GetEntry(list, entry);
    }

    public static Object OutputAsObject(DefaultListModel list, int entry) {
        return GetEntry(list, entry);
    }

    public static int OutputAsInteger(DefaultListModel list, int entry) {
        return Integer.parseInt(list.getElementAt(entry).toString());
    }

    public static double OutputAsDouble(DefaultListModel list, int entry) {
        return Double.parseDouble(list.getElementAt(entry).toString());
    }

    public static byte OutputAsByte(DefaultListModel list, int entry) {
        return Byte.parseByte(list.getElementAt(entry).toString());
    }

    public static char OutputAsCharacter(DefaultListModel list, int entry) {
        return list.getElementAt(entry).toString().charAt(0);
    }

    public static String GetEntry(DefaultListModel list, int entry) {
        String result = "";
        result = list.getElementAt(entry).toString();
        return result;
    }

    public static void AddEntry(DefaultListModel list, String entry) {
        list.addElement(entry);
    }

    public static void RemoveEntry(DefaultListModel list, int entry) {
        list.removeElementAt(entry);
    }

    public static DefaultListModel StrToList(String input, String delimiter) {
        DefaultListModel dlmtemp = new DefaultListModel();
        input = input.trim();
        delimiter = delimiter.trim();
        while (input.toLowerCase().contains(delimiter.toLowerCase())) {
            int index = input.toLowerCase().indexOf(delimiter.toLowerCase());
            dlmtemp.addElement(input.substring(0, index).trim());
            input = input.substring(index + delimiter.length(), input.length()).trim();
        }
        return dlmtemp;
    }

    public static String ListToStr(DefaultListModel list, String delimiter) {
        String result = "";
        for (int i = 0; i < list.size(); i++) {
            result = list.getElementAt(i).toString() + delimiter;
        }
        result = result.trim();
        return result;
    }

    public static String LoadFile(String inputfile) throws IOException {
        int len;
        char[] chr = new char[4096];
        final StringBuffer buffer = new StringBuffer();
        final FileReader reader = new FileReader(new File(inputfile));
        try {
            while ((len = reader.read(chr)) > 0) {
                buffer.append(chr, 0, len);
            }
        } finally {
            reader.close();
        }
        return buffer.toString();
    }

    public static void SaveFile(String outputfile, String outputstring) {
        try {
            FileWriter f0 = new FileWriter(new File(outputfile));
            f0.write(outputstring);
            f0.flush();
            f0.close();
        } catch (IOException ex) {
            Logger.getLogger(StringList.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

OutputAs methods are for outputting an entry as int, double, etc... so that you don't have to convert from string on the other side.

SaveFile & LoadFile are to save and load strings to and from files.

StrToList & ListToStr are to place delimiters between each entry.

ex. 1<>2<>3<>4<> if "<>" is the delimiter and 1 2 3 & 4 are the entries.

AddEntry & GetEntry are to add and get strings to and from the DefaultListModel.

RemoveEntry is to delete a string from the DefaultListModel.

You use the DefaultListModel instead of an array here like this:

DefaultListModel list = new DefaultListModel();
//now that you have a list, you can run it through the above class methods.

Casting a number to a string in TypeScript

"Casting" is different than conversion. In this case, window.location.hash will auto-convert a number to a string. But to avoid a TypeScript compile error, you can do the string conversion yourself:

window.location.hash = ""+page_number; 
window.location.hash = String(page_number); 

These conversions are ideal if you don't want an error to be thrown when page_number is null or undefined. Whereas page_number.toString() and page_number.toLocaleString() will throw when page_number is null or undefined.

When you only need to cast, not convert, this is how to cast to a string in TypeScript:

window.location.hash = <string>page_number; 
// or 
window.location.hash = page_number as string;

The <string> or as string cast annotations tell the TypeScript compiler to treat page_number as a string at compile time; it doesn't convert at run time.

However, the compiler will complain that you can't assign a number to a string. You would have to first cast to <any>, then to <string>:

window.location.hash = <string><any>page_number;
// or
window.location.hash = page_number as any as string;

So it's easier to just convert, which handles the type at run time and compile time:

window.location.hash = String(page_number); 

(Thanks to @RuslanPolutsygan for catching the string-number casting issue.)

Unable to create Genymotion Virtual Device

We had the same issues, it was because we had wrong version of Oracle VM Virtual Box. Make sure you uninstall wrong version and re-install Compatible Oracle VM Virtual Box.

What does map(&:name) mean in Ruby?

First, &:name is a shortcut for &:name.to_proc, where :name.to_proc returns a Proc (something that is similar, but not identical to a lambda) that when called with an object as (first) argument, calls the name method on that object.

Second, while & in def foo(&block) ... end converts a block passed to foo to a Proc, it does the opposite when applied to a Proc.

Thus, &:name.to_proc is a block that takes an object as argument and calls the name method on it, i. e. { |o| o.name }.

'Found the synthetic property @panelState. Please include either "BrowserAnimationsModule" or "NoopAnimationsModule" in your application.'

I ran into similar issues, when I tried to use the BrowserAnimationsModule. Following steps solved my problem:

  1. Delete the node_modules dir
  2. Clear your package cache using npm cache clean
  3. Run one of these two commands listed here to update your existing packages

If you experience a 404 errors like

http://.../node_modules/@angular/platform-browser/bundles/platform-browser.umd.js/animations

add following entries to map in your system.config.js:

'@angular/animations': 'node_modules/@angular/animations/bundles/animations.umd.min.js',
'@angular/animations/browser':'node_modules/@angular/animations/bundles/animations-browser.umd.js',
'@angular/platform-browser/animations': 'node_modules/@angular/platform-browser/bundles/platform-browser-animations.umd.js'

naveedahmed1 provided the solution on this github issue.

How to set cursor position in EditText?

as a reminder: if you are using edittext.setSelection() to set the cursor, and it is NOT working while setting up an alertdialog for example, make sure to set the selection() AFTER the dialog has been created

example:

AlertDialog dialog = builder.show();
input.setSelection(x,y);

How to fill in proxy information in cntlm config file?

Update your user, domain, and proxy information in cntlm.ini, then test your proxy with this command (run in your Cntlm installation folder):

cntlm -c cntlm.ini -I -M http://google.ro

It will ask for your password, and hopefully print your required authentication information, which must be saved in your cntlm.ini

Sample cntlm.ini:

Username            user
Domain              domain

# provide actual value if autodetection fails
# Workstation         pc-name

Proxy               my_proxy_server.com:80
NoProxy             127.0.0.*, 192.168.*

Listen              127.0.0.1:54321
Listen              192.168.1.42:8080
Gateway             no

SOCKS5Proxy         5000
# provide socks auth info if you want it
# SOCKS5User          socks-user:socks-password

# printed authentication info from the previous step
Auth            NTLMv2
PassNTLMv2      98D6986BCFA9886E41698C1686B58A09

Note: on linux the config file is cntlm.conf

java.util.Date vs java.sql.Date

The java.util.Date class in Java represents a particular moment in time (e,.g., 2013 Nov 25 16:30:45 down to milliseconds), but the DATE data type in the DB represents a date only (e.g., 2013 Nov 25). To prevent you from providing a java.util.Date object to the DB by mistake, Java doesn’t allow you to set a SQL parameter to java.util.Date directly:

PreparedStatement st = ...
java.util.Date d = ...
st.setDate(1, d); //will not work

But it still allows you to do that by force/intention (then hours and minutes will be ignored by the DB driver). This is done with the java.sql.Date class:

PreparedStatement st = ...
java.util.Date d = ...
st.setDate(1, new java.sql.Date(d.getTime())); //will work

A java.sql.Date object can store a moment in time (so that it’s easy to construct from a java.util.Date) but will throw an exception if you try to ask it for the hours (to enforce its concept of being a date only). The DB driver is expected to recognize this class and just use 0 for the hours. Try this:

public static void main(String[] args) {
  java.util.Date d1 = new java.util.Date(12345);//ms since 1970 Jan 1 midnight
  java.sql.Date d2 = new java.sql.Date(12345);
  System.out.println(d1.getHours());
  System.out.println(d2.getHours());
}

How can I pass a parameter to a Java Thread?

You can derive a class from Runnable, and during the construction (say) pass the parameter in.

Then launch it using Thread.start(Runnable r);

If you mean whilst the thread is running, then simply hold a reference to your derived object in the calling thread, and call the appropriate setter methods (synchronising where appropriate)

Show popup after page load

If you don't want to use jquery, use this:

<script>
 // without jquery
document.addEventListener("DOMContentLoaded", function() {
 setTimeout(function() {
  // run your open popup function after 5 sec = 5000
  PopUp();
 }, 5000)
});
</script>

OR With jquery

<script>
  $(document).ready(function(){
   setTimeout(function(){
   // open popup after 5 seconds
   PopUp();
  },5000);  
 });
</script>

Run a batch file with Windows task scheduler

Try run the task with high privileges.

put a \ at the end of path in "start in folder" such as c:\temp\

I do not know why , but this works for me sometimes.

How to animate a View with Translate Animation in Android

In order to move a View anywhere on the screen, I would recommend placing it in a full screen layout. By doing so, you won't have to worry about clippings or relative coordinates.

You can try this sample code:

main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" android:id="@+id/rootLayout">

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="MOVE" android:layout_centerHorizontal="true"/>

    <ImageView
        android:id="@+id/img1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" android:layout_marginLeft="10dip"/>
    <ImageView
        android:id="@+id/img2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" android:layout_centerVertical="true" android:layout_alignParentRight="true"/>
    <ImageView
        android:id="@+id/img3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/ic_launcher" android:layout_marginLeft="60dip" android:layout_alignParentBottom="true" android:layout_marginBottom="100dip"/>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:orientation="vertical" android:clipChildren="false" android:clipToPadding="false">

        <ImageView
            android:id="@+id/img4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/ic_launcher" android:layout_marginLeft="60dip" android:layout_marginTop="150dip"/>
    </LinearLayout>

</RelativeLayout>

Your activity

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    ((Button) findViewById( R.id.btn1 )).setOnClickListener( new OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            ImageView img = (ImageView) findViewById( R.id.img1 );              
            moveViewToScreenCenter( img );
            img = (ImageView) findViewById( R.id.img2 );
            moveViewToScreenCenter( img );
            img = (ImageView) findViewById( R.id.img3 );                
            moveViewToScreenCenter( img );
            img = (ImageView) findViewById( R.id.img4 );
            moveViewToScreenCenter( img );
        }
    });
}

private void moveViewToScreenCenter( View view )
{
    RelativeLayout root = (RelativeLayout) findViewById( R.id.rootLayout );
    DisplayMetrics dm = new DisplayMetrics();
    this.getWindowManager().getDefaultDisplay().getMetrics( dm );
    int statusBarOffset = dm.heightPixels - root.getMeasuredHeight();

    int originalPos[] = new int[2];
    view.getLocationOnScreen( originalPos );

    int xDest = dm.widthPixels/2;
    xDest -= (view.getMeasuredWidth()/2);
    int yDest = dm.heightPixels/2 - (view.getMeasuredHeight()/2) - statusBarOffset;

    TranslateAnimation anim = new TranslateAnimation( 0, xDest - originalPos[0] , 0, yDest - originalPos[1] );
    anim.setDuration(1000);
    anim.setFillAfter( true );
    view.startAnimation(anim);
}

The method moveViewToScreenCenter gets the View's absolute coordinates and calculates how much distance has to move from its current position to reach the center of the screen. The statusBarOffset variable measures the status bar height.

I hope you can keep going with this example. Remember that after the animation your view's position is still the initial one. If you tap the MOVE button again and again the same movement will repeat. If you want to change your view's position do it after the animation is finished.

How to use SqlClient in ASP.NET Core?

I think you may have missed this part in the tutorial:

Instead of referencing System.Data and System.Data.SqlClient you need to grab from Nuget:

System.Data.Common and System.Data.SqlClient.

Currently this creates dependency in project.json –> aspnetcore50 section to these two libraries.

"aspnetcore50": {
       "dependencies": {
           "System.Runtime": "4.0.20-beta-22523",
           "System.Data.Common": "4.0.0.0-beta-22605",
           "System.Data.SqlClient": "4.0.0.0-beta-22605"
       }
}

Try getting System.Data.Common and System.Data.SqlClient via Nuget and see if this adds the above dependencies for you, but in a nutshell you are missing System.Runtime.

Edit: As per Mozarts answer, if you are using .NET Core 3+, reference Microsoft.Data.SqlClient instead.

Running Java Program from Command Line Linux

Guys let's understand the syntax of it.

  1. If class file is present in the Current Dir.

    java -cp . fileName

  2. If class file is present within the Dir. Go to the Parent Dir and enter below cmd.

    java -cp . dir1.dir2.dir3.fileName

  3. If there is a dependency on external jars then,

    java -cp .:./jarName1:./jarName2 fileName

    Hope this helps.

MongoDB: How to update multiple documents with a single command?

Starting in v3.3 You can use updateMany

db.collection.updateMany(
   <filter>,
   <update>,
   {
     upsert: <boolean>,
     writeConcern: <document>,
     collation: <document>,
     arrayFilters: [ <filterdocument1>, ... ]
   }
)

In v2.2, the update function takes the following form:

 db.collection.update(
   <query>,
   <update>,
   { upsert: <boolean>, multi: <boolean> }
)

https://docs.mongodb.com/manual/reference/method/db.collection.update/

How do I create a Python function with optional arguments?

Just use the *args parameter, which allows you to pass as many arguments as you want after your a,b,c. You would have to add some logic to map args->c,d,e,f but its a "way" of overloading.

def myfunc(a,b, *args, **kwargs):
   for ar in args:
      print ar
myfunc(a,b,c,d,e,f)

And it will print values of c,d,e,f


Similarly you could use the kwargs argument and then you could name your parameters.

def myfunc(a,b, *args, **kwargs):
      c = kwargs.get('c', None)
      d = kwargs.get('d', None)
      #etc
myfunc(a,b, c='nick', d='dog', ...)

And then kwargs would have a dictionary of all the parameters that are key valued after a,b

Convert INT to VARCHAR SQL

CONVERT(DATA_TYPE , Your_Column) is the syntax for CONVERT method in SQL. From this convert function we can convert the data of the Column which is on the right side of the comma (,) to the data type in the left side of the comma (,) Please see below example.

SELECT CONVERT (VARCHAR(10), ColumnName) FROM TableName

git remove merge commit from history

Do git rebase -i <sha before the branches diverged> this will allow you to remove the merge commit and the log will be one single line as you wanted. You can also delete any commits that you do not want any more. The reason that your rebase wasn't working was that you weren't going back far enough.

WARNING: You are rewriting history doing this. Doing this with changes that have been pushed to a remote repo will cause issues. I recommend only doing this with commits that are local.

SQL update from one Table to another based on a ID match

I thought this is a simple example might someone get it easier,

        DECLARE @TB1 TABLE
        (
            No Int
            ,Name NVarchar(50)
        )

        DECLARE @TB2 TABLE
        (
            No Int
            ,Name NVarchar(50)
        )

        INSERT INTO @TB1 VALUES(1,'asdf');
        INSERT INTO @TB1 VALUES(2,'awerq');


        INSERT INTO @TB2 VALUES(1,';oiup');
        INSERT INTO @TB2 VALUES(2,'lkjhj');

        SELECT * FROM @TB1

        UPDATE @TB1 SET Name =S.Name
        FROM @TB1 T
        INNER JOIN @TB2 S
                ON S.No = T.No

        SELECT * FROM @TB1

How to throw a C++ exception

Simple:

#include <stdexcept>

int compare( int a, int b ) {
    if ( a < 0 || b < 0 ) {
        throw std::invalid_argument( "received negative value" );
    }
}

The Standard Library comes with a nice collection of built-in exception objects you can throw. Keep in mind that you should always throw by value and catch by reference:

try {
    compare( -1, 3 );
}
catch( const std::invalid_argument& e ) {
    // do stuff with exception... 
}

You can have multiple catch() statements after each try, so you can handle different exception types separately if you want.

You can also re-throw exceptions:

catch( const std::invalid_argument& e ) {
    // do something

    // let someone higher up the call stack handle it if they want
    throw;
}

And to catch exceptions regardless of type:

catch( ... ) { };

How to get the list of properties of a class?

Here is improved @lucasjones answer. I included improvements mentioned in comment section after his answer. I hope someone will find this useful.

public static string[] GetTypePropertyNames(object classObject,  BindingFlags bindingFlags)
{
    if (classObject == null)
    {
        throw new ArgumentNullException(nameof(classObject));
    }

        var type = classObject.GetType();
        var propertyInfos = type.GetProperties(bindingFlags);

        return propertyInfos.Select(propertyInfo => propertyInfo.Name).ToArray();
 }

How to write ternary operator condition in jQuery?

From what it looks like you are trying to do, toggle might better solve your problem.

EDIT: Sorry, toggle is just visibility, I don't think it will help your bg color toggling.

But here you go:

var box = $("#blackbox");
box.css('background') == 'pink' ? box.css({'background':'black'}) : box.css({'background':'pink'}); 

Effective method to hide email from spam bots

One easy solution is to use HTML entities instead of actual characters. For example, the "[email protected]" will be converted into :

<a href="&#109;&#97;&#105;&#108;&#116;&#111;&#58;&#109;&#101;&#64;&#101;&#120;&#97;&#109;&#112;&#108;&#101;&#46;&#99;&#111;&#109;">email me</A>

How to find most common elements of a list?

nltk is convenient for a lot of language processing stuff. It has methods for frequency distribution built in. Something like:

import nltk
fdist = nltk.FreqDist(your_list) # creates a frequency distribution from a list
most_common = fdist.max()    # returns a single element
top_three = fdist.keys()[:3] # returns a list

How to concatenate strings in django templates?

You can't do variable manipulation in django templates. You have two options, either write your own template tag or do this in view,

OpenSSL Command to check if a server is presenting a certificate

I was debugging an SSL issue today which resulted in the same write:errno=104 error. Eventually I found out that the reason for this behaviour was that the server required SNI (servername TLS extensions) to work correctly. Supplying the -servername option to openssl made it connect successfully:

openssl s_client -connect domain.tld:443 -servername domain.tld

Hope this helps.

Retrieving Dictionary Value Best Practices

TryGetValue is slightly faster, because FindEntry will only be called once.

How much faster? It depends on the dataset at hand. When you call the Contains method, Dictionary does an internal search to find its index. If it returns true, you need another index search to get the actual value. When you use TryGetValue, it searches only once for the index and if found, it assigns the value to your variable.

FYI: It's not actually catching an error.

It's calling:

public bool TryGetValue(TKey key, out TValue value)
{
    int index = this.FindEntry(key);
    if (index >= 0)
    {
        value = this.entries[index].value;
        return true;
    }
    value = default(TValue);
    return false;
}

ContainsKey is this:

public bool ContainsKey(TKey key)
{
    return (this.FindEntry(key) >= 0);
}

How can I add new array elements at the beginning of an array in Javascript?

Using splice we insert an element to an array at the begnning:

arrName.splice( 0, 0, 'newName1' );

Rails and PostgreSQL: Role postgres does not exist

I met this issue right on when I first install the Heroku's POSTGRES.app thing. After one morning trial and error i think this one line of code solved problem. As describe earlier, this is because postgresql does not have default role the first time it is set up. And we need to set that.

sovanlandy=# CREATE ROLE postgres LOGIN;

You must log in to your respective psql console to use this psql command.

Also noted that, if you already created the role 'postgre' but still get permission errors, you need to alter with command:

sovanlandy=# ALTER ROLE postgres LOGIN;

Hope it helps!

Convert String to double in Java

Using Double.parseDouble() without surrounding try/catch block can cause potential NumberFormatException had the input double string not conforming to a valid format.

Guava offers a utility method for this which returns null in case your String can't be parsed.

https://google.github.io/guava/releases/19.0/api/docs/com/google/common/primitives/Doubles.html#tryParse(java.lang.String)

Double valueDouble = Doubles.tryParse(aPotentiallyCorruptedDoubleString);

In runtime, a malformed String input yields null assigned to valueDouble

How to list AD group membership for AD users using input list?

Get-ADPrincipalGroupMembership username | select name

Got it from another answer but the script works magic. :)

Get generic type of java.util.List

The generic type of a collection should only matter if it actually has objects in it, right? So isn't it easier to just do:

Collection<?> myCollection = getUnknownCollectionFromSomewhere();
Class genericClass = null;
Iterator it = myCollection.iterator();
if (it.hasNext()){
    genericClass = it.next().getClass();
}
if (genericClass != null) { //do whatever we needed to know the type for

There's no such thing as a generic type in runtime, but the objects inside at runtime are guaranteed to be the same type as the declared generic, so it's easy enough just to test the item's class before we process it.

Another thing you can do is simply process the list to get members that are the right type, ignoring others (or processing them differently).

Map<Class<?>, List<Object>> classObjectMap = myCollection.stream()
    .filter(Objects::nonNull)
    .collect(Collectors.groupingBy(Object::getClass));

// Process the list of the correct class, and/or handle objects of incorrect
// class (throw exceptions, etc). You may need to group subclasses by
// filtering the keys. For instance:

List<Number> numbers = classObjectMap.entrySet().stream()
        .filter(e->Number.class.isAssignableFrom(e.getKey()))
        .flatMap(e->e.getValue().stream())
        .map(Number.class::cast)
        .collect(Collectors.toList());

This will give you a list of all items whose classes were subclasses of Number which you can then process as you need. The rest of the items were filtered out into other lists. Because they're in the map, you can process them as desired, or ignore them.

If you want to ignore items of other classes altogether, it becomes much simpler:

List<Number> numbers = myCollection.stream()
    .filter(Number.class::isInstance)
    .map(Number.class::cast)
    .collect(Collectors.toList());

You can even create a utility method to insure that a list contains ONLY those items matching a specific class:

public <V> List<V> getTypeSafeItemList(Collection<Object> input, Class<V> cls) {
    return input.stream()
            .filter(cls::isInstance)
            .map(cls::cast)
            .collect(Collectors.toList());
}

SQL How to Select the most recent date item

With SQL Server try:

SELECT TOP 1 * FROM dbo.youTable WHERE user_id = 'userid' ORDER BY date_added desc

Return char[]/string from a function

char* charP = createStr();

Would be correct if your function was correct. Unfortunately you are returning a pointer to a local variable in the function which means that it is a pointer to undefined data as soon as the function returns. You need to use heap allocation like malloc for the string in your function in order for the pointer you return to have any meaning. Then you need to remember to free it later.

Ignore Duplicates and Create New List of Unique Values in Excel

All you have to do is : Go to Data tab Chose advanced in Sort & Filter In actions select : copy to another location if want a new list - Copy to any location In list range chose the list you want to get the records off . And the most important thing is to check : Unique records only .

Compiler error: "class, interface, or enum expected"

You forgot your class declaration:

public class MyClass {
...

How can I completely remove TFS Bindings

Next works for me:

  1. Delete all .vssscc (solution binding) and .vspscc (project binding) files
  2. Remove block GlobalSection(TeamFoundationVersionControl) = preSolution from solution file

There could be also information regarding source control in the proj file in tags

<SccProjectName>SAK</SccProjectName> <SccLocalPath>SAK</SccLocalPath> <SccAuxPath>SAK</SccAuxPath> <SccProvider>SAK</SccProvider>

SAK states for "Should Already Know", so it can be kept.

SQL how to check that two tables has exactly the same data?

Taking the script from onedaywhen, I modified it to also show which table each entry comes from.

DECLARE @table1 NVARCHAR(80)= 'table 1 name'
DECLARE @table2 NVARCHAR(80)= 'table 2 name'
DECLARE @sql NVARCHAR (1000)

SET @sql = 
'
SELECT ''' + @table1 + ''' AS table_name,* FROM
(
SELECT * FROM ' + @table1 + '
EXCEPT
SELECT * FROM ' + @table2 + '
) x

UNION 

SELECT ''' + @table2 + ''' AS table_name,* FROM 
(
SELECT * FROM ' + @table2 + '
EXCEPT
SELECT * FROM ' + @table1 + '
) y
'

EXEC sp_executesql @stmt = @sql

how to fix Cannot call sendRedirect() after the response has been committed?

you can't call sendRedirect(), after you have already used forward(). So, you get that exception.

Grep regex NOT containing string

(?<!1\.2\.3\.4).*Has exploded

You need to run this with -P to have negative lookbehind (Perl regular expression), so the command is:

grep -P '(?<!1\.2\.3\.4).*Has exploded' test.log

Try this. It uses negative lookbehind to ignore the line if it is preceeded by 1.2.3.4. Hope that helps!

Check if an element is present in a Bash array

array=("word" "two words") # let's look for "two words"

using grep and printf:

(printf '%s\n' "${array[@]}" | grep -x -q "two words") && <run_your_if_found_command_here>

using for:

(for e in "${array[@]}"; do [[ "$e" == "two words" ]] && exit 0; done; exit 1) && <run_your_if_found_command_here>

For not_found results add || <run_your_if_notfound_command_here>

add onclick function to a submit button

if you need to do something before submitting data, you could use form's onsubmit.

<form method=post onsubmit="return doSomething()">
  <input type=text name=text1>
  <input type=submit>
</form>

How to truncate string using SQL server

     CASE
     WHEN col IS NULL
        THEN ''
     ELSE SUBSTRING(col,1,15)+ '...' 
     END AS Col

Create a CSS rule / class with jQuery at runtime

You can create style element and insert it into DOM

$("<style type='text/css'> .redbold{ color:#f00; font-weight:bold;} </style>").appendTo("head");
$("<div/>").addClass("redbold").text("SOME NEW TEXT").appendTo("body");

tested on Opera10 FF3.5 iE8 iE6

JavaScript: Upload file

Pure JS

You can use fetch optionally with await-try-catch

let photo = document.getElementById("image-file").files[0];
let formData = new FormData();
     
formData.append("photo", photo);
fetch('/upload/image', {method: "POST", body: formData});

_x000D_
_x000D_
async function SavePhoto(inp) 
{
    let user = { name:'john', age:34 };
    let formData = new FormData();
    let photo = inp.files[0];      
         
    formData.append("photo", photo);
    formData.append("user", JSON.stringify(user)); 
    
    const ctrl = new AbortController()    // timeout
    setTimeout(() => ctrl.abort(), 5000);
    
    try {
       let r = await fetch('/upload/image', 
         {method: "POST", body: formData, signal: ctrl.signal}); 
       console.log('HTTP response code:',r.status); 
    } catch(e) {
       console.log('Huston we have problem...:', e);
    }
    
}
_x000D_
<input id="image-file" type="file" onchange="SavePhoto(this)" >
<br><br>
Before selecting the file open chrome console > network tab to see the request details.
<br><br>
<small>Because in this example we send request to https://stacksnippets.net/upload/image the response code will be 404 ofcourse...</small>

<br><br>
(in stack overflow snippets there is problem with error handling, however in <a href="https://jsfiddle.net/Lamik/b8ed5x3y/5/">jsfiddle version</a> for 404 errors 4xx/5xx are <a href="https://stackoverflow.com/a/33355142/860099">not throwing</a> at all but we can read response status which contains code)
_x000D_
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Old school approach - xhr

let photo = document.getElementById("image-file").files[0];  // file from input
let req = new XMLHttpRequest();
let formData = new FormData();

formData.append("photo", photo);                                
req.open("POST", '/upload/image');
req.send(formData);

_x000D_
_x000D_
function SavePhoto(e) 
{
    let user = { name:'john', age:34 };
    let xhr = new XMLHttpRequest();
    let formData = new FormData();
    let photo = e.files[0];      
    
    formData.append("user", JSON.stringify(user));   
    formData.append("photo", photo);
    
    xhr.onreadystatechange = state => { console.log(xhr.status); } // err handling
    xhr.timeout = 5000;
    xhr.open("POST", '/upload/image'); 
    xhr.send(formData);
}
_x000D_
<input id="image-file" type="file" onchange="SavePhoto(this)" >
<br><br>
Choose file and open chrome console > network tab to see the request details.
<br><br>
<small>Because in this example we send request to https://stacksnippets.net/upload/image the response code will be 404 ofcourse...</small>

<br><br>
(the stack overflow snippets, has some problem with error handling - the xhr.status is zero (instead of 404) which is similar to situation when we run script from file on <a href="https://stackoverflow.com/a/10173639/860099">local disc</a> - so I provide also js fiddle version which shows proper http error code <a href="https://jsfiddle.net/Lamik/k6jtq3uh/2/">here</a>)
_x000D_
_x000D_
_x000D_

SUMMARY

  • In server side you can read original file name (and other info) which is automatically included to request by browser in filename formData parameter.
  • You do NOT need to set request header Content-Type to multipart/form-data - this will be set automatically by browser.
  • Instead of /upload/image you can use full address like http://.../upload/image.
  • If you want to send many files in single request use multiple attribute: <input multiple type=... />, and attach all chosen files to formData in similar way (e.g. photo2=...files[2];... formData.append("photo2", photo2);)
  • You can include additional data (json) to request e.g. let user = {name:'john', age:34} in this way: formData.append("user", JSON.stringify(user));
  • You can set timeout: for fetch using AbortController, for old approach by xhr.timeout= milisec
  • This solutions should work on all major browsers.

How to reference a method in javadoc?

you can use @see to do that:

sample:

interface View {
        /**
         * @return true: have read contact and call log permissions, else otherwise
         * @see #requestReadContactAndCallLogPermissions()
         */
        boolean haveReadContactAndCallLogPermissions();

        /**
         * if not have permissions, request to user for allow
         * @see #haveReadContactAndCallLogPermissions()
         */
        void requestReadContactAndCallLogPermissions();
    }

Jackson enum Serializing and DeSerializer

You can customize the deserialization for any attribute.

Declare your deserialize class using the annotationJsonDeserialize (import com.fasterxml.jackson.databind.annotation.JsonDeserialize) for the attribute that will be processed. If this is an Enum:

@JsonDeserialize(using = MyEnumDeserialize.class)
private MyEnum myEnum;

This way your class will be used to deserialize the attribute. This is a full example:

public class MyEnumDeserialize extends JsonDeserializer<MyEnum> {

    @Override
    public MyEnum deserialize(JsonParser jsonParser, DeserializationContext deserializationContext) throws IOException {
        JsonNode node = jsonParser.getCodec().readTree(jsonParser);
        MyEnum type = null;
        try{
            if(node.get("attr") != null){
                type = MyEnum.get(Long.parseLong(node.get("attr").asText()));
                if (type != null) {
                    return type;
                }
            }
        }catch(Exception e){
            type = null;
        }
        return type;
    }
}

XDocument or XmlDocument

If you're using .NET version 3.0 or lower, you have to use XmlDocument aka the classic DOM API. Likewise you'll find there are some other APIs which will expect this.

If you get the choice, however, I would thoroughly recommend using XDocument aka LINQ to XML. It's much simpler to create documents and process them. For example, it's the difference between:

XmlDocument doc = new XmlDocument();
XmlElement root = doc.CreateElement("root");
root.SetAttribute("name", "value");
XmlElement child = doc.CreateElement("child");
child.InnerText = "text node";
root.AppendChild(child);
doc.AppendChild(root);

and

XDocument doc = new XDocument(
    new XElement("root",
                 new XAttribute("name", "value"),
                 new XElement("child", "text node")));

Namespaces are pretty easy to work with in LINQ to XML, unlike any other XML API I've ever seen:

XNamespace ns = "http://somewhere.com";
XElement element = new XElement(ns + "elementName");
// etc

LINQ to XML also works really well with LINQ - its construction model allows you to build elements with sequences of sub-elements really easily:

// Customers is a List<Customer>
XElement customersElement = new XElement("customers",
    customers.Select(c => new XElement("customer",
        new XAttribute("name", c.Name),
        new XAttribute("lastSeen", c.LastOrder)
        new XElement("address",
            new XAttribute("town", c.Town),
            new XAttribute("firstline", c.Address1),
            // etc
    ));

It's all a lot more declarative, which fits in with the general LINQ style.

Now as Brannon mentioned, these are in-memory APIs rather than streaming ones (although XStreamingElement supports lazy output). XmlReader and XmlWriter are the normal ways of streaming XML in .NET, but you can mix all the APIs to some extent. For example, you can stream a large document but use LINQ to XML by positioning an XmlReader at the start of an element, reading an XElement from it and processing it, then moving on to the next element etc. There are various blog posts about this technique, here's one I found with a quick search.

When to use static methods

After reading Misko's articles I believe that static methods are bad from a testing point of view. You should have factories instead(maybe using a dependency injection tool like Guice).

how do I ensure that I only have one of something

only have one of something The problem of “how do I ensure that I only have one of something” is nicely sidestepped. You instantiate only a single ApplicationFactory in your main, and as a result, you only instantiate a single instance of all of your singletons.

The basic issue with static methods is they are procedural code

The basic issue with static methods is they are procedural code. I have no idea how to unit-test procedural code. Unit-testing assumes that I can instantiate a piece of my application in isolation. During the instantiation I wire the dependencies with mocks/friendlies which replace the real dependencies. With procedural programing there is nothing to "wire" since there are no objects, the code and data are separate.

I can't delete a remote master branch on git

As explained in "Deleting your master branch" by Matthew Brett, you need to change your GitHub repo default branch.

You need to go to the GitHub page for your forked repository, and click on the “Settings” button.

Click on the "Branches" tab on the left hand side. There’s a “Default branch” dropdown list near the top of the screen.

From there, select placeholder (where placeholder is the dummy name for your new default branch).

Confirm that you want to change your default branch.

Now you can do (from the command line):

git push origin :master

Or, since 2012, you can delete that same branch directly on GitHub:

GitHub deletion

That was announced in Sept. 2013, a year after I initially wrote that answer.

For small changes like documentation fixes, typos, or if you’re just a walking software compiler, you can get a lot done in your browser without needing to clone the entire repository to your computer.


Note: for BitBucket, Tum reports in the comments:

About the same for Bitbucket

Repo -> Settings -> Repository details -> Main branch

What is define([ , function ]) in JavaScript?

define() is part of the AMD spec of js

See:

Edit: Also see Claudio's answer below. Likely the more relevant explanation.

Confirm Password with jQuery Validate

jQuery('.validatedForm').validate({
        rules : {
            password : {
                minlength : 5
            },
            password_confirm : {
                minlength : 5,
                equalTo : '[name="password"]'
            }
        }

In general, you will not use id="password" like this. So, you can use [name="password"] instead of "#password"

Linux Process States

While waiting for read() or write() to/from a file descriptor return, the process will be put in a special kind of sleep, known as "D" or "Disk Sleep". This is special, because the process can not be killed or interrupted while in such a state. A process waiting for a return from ioctl() would also be put to sleep in this manner.

An exception to this is when a file (such as a terminal or other character device) is opened in O_NONBLOCK mode, passed when its assumed that a device (such as a modem) will need time to initialize. However, you indicated block devices in your question. Also, I have never tried an ioctl() that is likely to block on a fd opened in non blocking mode (at least not knowingly).

How another process is chosen depends entirely on the scheduler you are using, as well as what other processes might have done to modify their weights within that scheduler.

Some user space programs under certain circumstances have been known to remain in this state forever, until rebooted. These are typically grouped in with other "zombies", but the term would not be correct as they are not technically defunct.

In Bootstrap 3,How to change the distance between rows in vertical?

UPDATE

Bootstrap 4 has spacing utilities to handle this https://getbootstrap.com/docs/4.0/utilities/spacing/

.mt-0 {
  margin-top: 0 !important;
}

--

ORIGINAL ANSWER

If you are using SASS, this is what I normally do.

$margins: (xs: 0.5rem, sm: 1rem, md: 1.5rem, lg: 2rem, xl: 2.5rem);

@each $name, $value in $margins {
  .margin-top-#{$name} {
    margin-top: $value;
  }

  .margin-bottom-#{$name} {
    margin-bottom: $value;
  }
}

so you can later use margin-top-xs for example

CSS Equivalent of the "if" statement

CSS itself doesn't have conditional statements, but here's a hack involving custom properties (a.k.a. "css variables").

In this trivial example, you want to apply a padding based on a certain condition—like an "if" statement.

:root   { --is-big: 0; }

.is-big { --is-big: 1; }

.block {
  padding: calc(
    4rem * var(--is-big) +
    1rem * (1 - var(--is-big))
  );
}

So any .block that's an .is-big or that's a descendant of one will have a padding of 4rem, while all other blocks will only have 1rem. Now I call this a "trivial" example because it can be done without the hack.

.block {
  padding: 1rem;
}

.is-big .block,
.block.is-big {
  padding: 4rem;
}

But I will leave its applications to your imagination.

What is going wrong when Visual Studio tells me "xcopy exited with code 4"

I ran across this issue, so I ran the xcopy command from the command line and it said:

File creation error - The requested operation cannot be performed on a file with
 a user-mapped section open.

It was actually Visual Studio holding onto something. I just restarted Visual Studio and it worked.

Run a PHP file in a cron job using CPanel

This works fine and also sends email:

/usr/bin/php /home/xxYourUserNamexx/public_html/xxYourFolderxx/xxcronfile.php

The following two commands also work fine but do not send email:

/usr/bin/php -f /home/Same As Above

php -f /home/Same As Above

Display a angular variable in my html page

In your template, you have access to all the variables that are members of the current $scope. So, tobedone should be $scope.tobedone, and then you can display it with {{tobedone}}, or [[tobedone]] in your case.

Ansible - read inventory hosts and variables to group_vars/all file

- name: host
   debug: msg="{{ item }}" 
   with_items:
    - "{{ groups['tests'] }}"

This piece of code will give the message:

'10.112.84.122'
'10.112.84.124'

as groups['tests'] basically return a list of unique ip addresses ['10.112.84.122','10.112.84.124'] whereas groups['tomcat'][0] returns 10.112.84.124.

Get original URL referer with PHP?

As Johnathan Suggested, you would either want to save it in a cookie or a session.

The easier way would be to use a Session variable.

session_start();
if(!isset($_SESSION['org_referer']))
{
    $_SESSION['org_referer'] = $_SERVER['HTTP_REFERER'];
}

Put that at the top of the page, and you will always be able to access the first referer that the site visitor was directed by.

Making an asynchronous task in Flask

You can also try using multiprocessing.Process with daemon=True; the process.start() method does not block and you can return a response/status immediately to the caller while your expensive function executes in the background.

I experienced similar problem while working with falcon framework and using daemon process helped.

You'd need to do the following:

from multiprocessing import Process

@app.route('/render/<id>', methods=['POST'])
def render_script(id=None):
    ...
    heavy_process = Process(  # Create a daemonic process with heavy "my_func"
        target=my_func,
        daemon=True
    )
    heavy_process.start()
    return Response(
        mimetype='application/json',
        status=200
    )

# Define some heavy function
def my_func():
    time.sleep(10)
    print("Process finished")

You should get a response immediately and, after 10s you should see a printed message in the console.

NOTE: Keep in mind that daemonic processes are not allowed to spawn any child processes.

In C#, why is String a reference type that behaves like a value type?

The distinction between reference types and value types are basically a performance tradeoff in the design of the language. Reference types have some overhead on construction and destruction and garbage collection, because they are created on the heap. Value types on the other hand have overhead on method calls (if the data size is larger than a pointer), because the whole object is copied rather than just a pointer. Because strings can be (and typically are) much larger than the size of a pointer, they are designed as reference types. Also, as Servy pointed out, the size of a value type must be known at compile time, which is not always the case for strings.

The question of mutability is a separate issue. Both reference types and value types can be either mutable or immutable. Value types are typically immutable though, since the semantics for mutable value types can be confusing.

Reference types are generally mutable, but can be designed as immutable if it makes sense. Strings are defined as immutable because it makes certain optimizations possible. For example, if the same string literal occurs multiple times in the same program (which is quite common), the compiler can reuse the same object.

So why is "==" overloaded to compare strings by text? Because it is the most useful semantics. If two strings are equal by text, they may or may not be the same object reference due to the optimizations. So comparing references are pretty useless, while comparing text are almost always what you want.

Speaking more generally, Strings has what is termed value semantics. This is a more general concept than value types, which is a C# specific implementation detail. Value types have value semantics, but reference types may also have value semantics. When a type have value semantics, you can't really tell if the underlying implementation is a reference type or value type, so you can consider that an implementation detail.

How to create a file in a directory in java?

A better and simpler way to do that :

File f = new File("C:/a/b/test.txt");
if(!f.exists()){
   f.createNewFile();
}

Source

Query to select data between two dates with the format m/d/yyyy

select * from xxx where dates between '2012-10-10' and '2012-10-12'

I always use YYYY-MM-DD in my views and never had any issue. Plus, it is readable and non equivocal.
You should be aware that using BETWEEN might not return what you expect with a DATETIME field, since it would eliminate records dated '2012-10-12 08:00' for example.
I would rather use where dates >= '2012-10-10' and dates < '2012-10-13' (lower than next day)

Insert multiple lines into a file after specified pattern using shell script

You can use awk for inserting output of some command in the middle of input.txt.
The lines to be inserted can be the output of a cat otherfile, ls -l or 4 lines with a number generated by printf.

awk 'NR==FNR {a[NR]=$0;next}
    {print}
    /cdef/ {for (i=1; i <= length(a); i++) { print a[i] }}'
    <(printf "%s\n" line{1..4}) input.txt

How to Exit a Method without Exiting the Program?

If the function is a void, ending the function will return. Otherwise, you need to do an explicit return someValue. As Mark mentioned, you can also throw an exception. What's the context of your question? Do you have a larger code sample with which to show you some ways to exit the function?

Input Type image submit form value?

well if i was in your place i would do this.I would have an hidden field and based on the input image field i would change the hidden field value(jQuery), and then finally submit the hidden field whose value reflects the image field.

How to deal with a slow SecureRandom generator?

It sounds like you should be clearer about your RNG requirements. The strongest cryptographic RNG requirement (as I understand it) would be that even if you know the algorithm used to generate them, and you know all previously generated random numbers, you could not get any useful information about any of the random numbers generated in the future, without spending an impractical amount of computing power.

If you don't need this full guarantee of randomness then there are probably appropriate performance tradeoffs. I would tend to agree with Dan Dyer's response about AESCounterRNG from Uncommons-Maths, or Fortuna (one of its authors is Bruce Schneier, an expert in cryptography). I've never used either but the ideas appear reputable at first glance.

I would think that if you could generate an initial random seed periodically (e.g. once per day or hour or whatever), you could use a fast stream cipher to generate random numbers from successive chunks of the stream (if the stream cipher uses XOR then just pass in a stream of nulls or grab the XOR bits directly). ECRYPT's eStream project has lots of good information including performance benchmarks. This wouldn't maintain entropy between the points in time that you replenish it, so if someone knew one of the random numbers and the algorithm you used, technically it might be possible, with a lot of computing power, to break the stream cipher and guess its internal state to be able to predict future random numbers. But you'd have to decide whether that risk and its consequences are sufficient to justify the cost of maintaining entropy.

Edit: here's some cryptographic course notes on RNG I found on the 'net that look very relevant to this topic.

Cannot push to GitHub - keeps saying need merge

This normally happens when you git commit and try to git push changes before git pulling on that branch x where someone else has already made changes.

The normal flow would be as below,

STEP 1: git stash your local uncommitted changes on that branch.

STEP 2: git pull origin branch_name -v to pull and merge to locally committed changes on that branch (give this merge some message, and fix conflicts if any.)

STEP 3: git stash pop the stashed changes (Then you can make commits on popped files if you want or push already committed changes (STEP4) first and make new commit to files later.)

STEP 4: git push origin branch_name -v the merged changes.

Replace branch_name with master (for master branch).

Send password when using scp to copy files from one server to another

One of the ways to get around login issues with ssh, scp, and sftp (all use the same protocol and sshd server) is to create public/private key pairings.

Some servers may disallow this, but most sites don't. These directions are for Unix/Linux/Mac. As always, Windows is a wee bit different although the cygwin environment on Windows does follow these steps.

  • On your machine, create your public/private key using ssh-keygen. This can vary from system to system, but the program should lead you through this.
  • When ssh-keygen is finished, you will have a $HOME/.ssh directory on your machine. This directory will contain a public key and a private key. There will be two more files that are generated as you go along. One is known_hosts which contains the fingerprints of all known hosts you've logged into. The second will be called either authorized_keys or authorized_keys2 depending upon your implementation.
  • If it's not there already, log into the remote host, and run ssh-keygen there too. This will generate a $HOME/.ssh directory there as well as a private/public key pair. Don't do this if the $HOME/.ssh directory already exists and has a public and private key file. You don't want to regenerate it.
  • On the remote server in the $HOME/.ssh directory, create a file called authorized_keys. In this file, put your public key. This public key is found on your $HOME/.ssh directory on your local machine. It will end with *.pub. Paste the contents of that into authorized_keys. If authorized_keys already exists, paste your public key in the next line.

Now, when you log in using ssh, or you use scp or sftp, you will not be required to enter a password. By the way, the user IDs on the two machines do not have to agree. I've logged into many remote servers as a different user and setup my public key in authorized_keys and have no problems logging directly into that user.

Doing Private Public Key Authentication on Windows

If you use Windows, you will need something that can do ssh. Most people I know use PuTTY which can generate public/private keys, and do the key pairing when you login remotely. I can't remember all of the steps, but you generate two files (one contains the public key, one contains the private key), and configure PuTTY to use both of those when logging into a remote site. If that remote site is Linux/Unix/Mac, you can copy your public key and put it into the authorized_keys file.

If you can use SSH Public/Private keys, you can eliminate the need for passwords in your scripts. Otherwise, you will have to use something like Expect or Perl with Net::SSH which can watch the remote host and enter the password when prompted.

How can I create download link in HTML?

In addition (or in replacement) to the HTML5's <a download attribute already mentioned,
the browser's download to disk behavior can also be triggered by the following http response header:

Content-Disposition: attachment; filename=ProposedFileName.txt;

This was the way to do before HTML5 (and still works with browsers supporting HTML5).

How to get the children of the $(this) selector?

If you need to get the first img that's down exactly one level, you can do

$(this).children("img:first")

Calculate distance in meters when you know longitude and latitude in java

In C++ it is done like this:

#define LOCAL_PI 3.1415926535897932385 

double ToRadians(double degrees) 
{
  double radians = degrees * LOCAL_PI / 180;
  return radians;
}

double DirectDistance(double lat1, double lng1, double lat2, double lng2) 
{
  double earthRadius = 3958.75;
  double dLat = ToRadians(lat2-lat1);
  double dLng = ToRadians(lng2-lng1);
  double a = sin(dLat/2) * sin(dLat/2) + 
             cos(ToRadians(lat1)) * cos(ToRadians(lat2)) * 
             sin(dLng/2) * sin(dLng/2);
  double c = 2 * atan2(sqrt(a), sqrt(1-a));
  double dist = earthRadius * c;
  double meterConversion = 1609.00;
  return dist * meterConversion;
}

Using setattr() in python

I'm here in general only to find out that through dict it is necessary to work inside setattr XD

Created Button Click Event c#

You need an event handler which will fire when the button is clicked. Here is a quick way -

  var button = new Button();
  button.Text = "my button";

  this.Controls.Add(button);

  button.Click += (sender, args) =>
                       {
                           MessageBox.Show("Some stuff");
                           Close();
                       };

But it would be better to understand a bit more about buttons, events, etc.

If you use the visual studio UI to create a button and double click the button in design mode, this will create your event and hook it up for you. You can then go to the designer code (the default will be Form1.Designer.cs) where you will find the event:

 this.button1.Click += new System.EventHandler(this.button1_Click);

You will also see a LOT of other information setup for the button, such as location, etc. - which will help you create one the way you want and will improve your understanding of creating UI elements. E.g. a default button gives this on my 2012 machine:

        this.button1.Location = new System.Drawing.Point(128, 214);
        this.button1.Name = "button1";
        this.button1.Size = new System.Drawing.Size(75, 23);
        this.button1.TabIndex = 1;
        this.button1.Text = "button1";
        this.button1.UseVisualStyleBackColor = true;

As for closing the Form, it is as easy as putting Close(); within your event handler:

private void button1_Click(object sender, EventArgs e)
    {
       MessageBox.Show("some text");
       Close();
    }

Android Activity without ActionBar

Please find the default theme in styles.xml

<!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

And change parent this way

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">

Why is char[] preferred over String for passwords?

To quote an official document, the Java Cryptography Architecture guide says this about char[] vs. String passwords (about password-based encryption, but this is more generally about passwords of course):

It would seem logical to collect and store the password in an object of type java.lang.String. However, here's the caveat: Objects of type String are immutable, i.e., there are no methods defined that allow you to change (overwrite) or zero out the contents of a String after usage. This feature makes String objects unsuitable for storing security sensitive information such as user passwords. You should always collect and store security sensitive information in a char array instead.

Guideline 2-2 of the Secure Coding Guidelines for the Java Programming Language, Version 4.0 also says something similar (although it is originally in the context of logging):

Guideline 2-2: Do not log highly sensitive information

Some information, such as Social Security numbers (SSNs) and passwords, is highly sensitive. This information should not be kept for longer than necessary nor where it may be seen, even by administrators. For instance, it should not be sent to log files and its presence should not be detectable through searches. Some transient data may be kept in mutable data structures, such as char arrays, and cleared immediately after use. Clearing data structures has reduced effectiveness on typical Java runtime systems as objects are moved in memory transparently to the programmer.

This guideline also has implications for implementation and use of lower-level libraries that do not have semantic knowledge of the data they are dealing with. As an example, a low-level string parsing library may log the text it works on. An application may parse an SSN with the library. This creates a situation where the SSNs are available to administrators with access to the log files.

Find the most frequent number in a NumPy array

You may use

values, counts = np.unique(a, return_counts=True)

ind = np.argmax(counts)
print(values[ind])  # prints the most frequent element

ind = np.argpartition(-counts, kth=10)[:10]
print(values[ind])  # prints the 10 most frequent elements

If some element is as frequent as another one, this code will return only the first element.

how to query for a list<String> in jdbctemplate

Is there a way to have placeholders, like ? for column names? For example SELECT ? FROM TABLEA GROUP BY ?

Use dynamic query as below:

String queryString = "SELECT "+ colName+ " FROM TABLEA GROUP BY "+ colName;

If I want to simply run the above query and get a List what is the best way?

List<String> data = getJdbcTemplate().query(query, new RowMapper<String>(){
                            public String mapRow(ResultSet rs, int rowNum) 
                                                         throws SQLException {
                                    return rs.getString(1);
                            }
                       });

EDIT: To Stop SQL Injection, check for non word characters in the colName as :

          Pattern pattern = Pattern.compile("\\W");
          if(pattern.matcher(str).find()){
               //throw exception as invalid column name
          }

What's the best way to iterate an Android Cursor?

The best looking way I've found to go through a cursor is the following:

Cursor cursor;
... //fill the cursor here

for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
    // do what you need with the cursor here
}

Don't forget to close the cursor afterwards

EDIT: The given solution is great if you ever need to iterate a cursor that you are not responsible of. A good example would be, if you are taking a cursor as argument in a method, and you need to scan the cursor for a given value, without having to worry about the cursor's current position.

Is double square brackets [[ ]] preferable over single square brackets [ ] in Bash?

In a nutshell, [[ is better because it doesn't fork another process. No brackets or a single bracket is slower than a double bracket because it forks another process.

What Process is using all of my disk IO

iotop with the -a flag:

-a, --accumulated     show accumulated I/O instead of bandwidth

How do you convert a time.struct_time object into a datetime object?

Like this:

>>> structTime = time.localtime()
>>> datetime.datetime(*structTime[:6])
datetime.datetime(2009, 11, 8, 20, 32, 35)

Linq : select value in a datatable column

I notice others have given the non-lambda syntax so just to have this complete I'll put in the lambda syntax equivalent:

Non-lambda (as per James's post):

var name = from i in DataContext.MyTable
           where i.ID == 0
           select i.Name

Equivalent lambda syntax:

var name = DataContext.MyTable.Where(i => i.ID == 0)
                              .Select(i => new { Name = i.Name });

There's not really much practical difference, just personal opinion on which you prefer.

Fatal error: "No Target Architecture" in Visual Studio

It would seem that _AMD64_ is not defined, since I can't imagine you are compiling for Itanium (_IA64_).

PackagesNotFoundError: The following packages are not available from current channels:

Thanks, Max S. conda-forge worked for me as well.

scikit-learn on Anaconda-Jupyter Notebook.

Upgrading my scikit-learn from 0.19.1 to 0.19.2 in anaconda installed on Ubuntu on Google VM instance:

Run the following commands in the terminal:

First, check available the packages with versions

conda list    

It will show packages and their installed versions in the output:

scikit-learn              0.19.1           py36hedc7406_0  

Upgrade to 0.19.2 July 2018 release.

conda config --append channels conda-forge
conda install scikit-learn=0.19.2

Now check the version installed correctly or not?

conda list 

Output is:

scikit-learn              0.19.2          py36_blas_openblasha84fab4_201  [blas_openblas]  conda-forge

Note: Don't use pip command if you are using Anaconda or Miniconda

I tried following commands:

!conda update conda 
!pip install -U scikit-learn

It will install the required packages also will show in the conda list but when try to import that package it will not work.

On the website http://scikit-learn.org/stable/install.html it is mentioned as: Warning To upgrade or uninstall scikit-learn installed with Anaconda or conda you should not use the pip.

Sorting options elements alphabetically using jQuery

Yes you can sort the options by its text and append it back to the select box.

 function NASort(a, b) {    
      if (a.innerHTML == 'NA') {
          return 1;   
      }
      else if (b.innerHTML == 'NA') {
          return -1;   
      }       
      return (a.innerHTML > b.innerHTML) ? 1 : -1;
  };

Fiddle: https://jsfiddle.net/vaishali_ravisankar/5zfohf6v/

Calculating Covariance with Python and Numpy

When a and b are 1-dimensional sequences, numpy.cov(a,b)[0][1] is equivalent to your cov(a,b).

The 2x2 array returned by np.cov(a,b) has elements equal to

cov(a,a)  cov(a,b)

cov(a,b)  cov(b,b)

(where, again, cov is the function you defined above.)

What happens if you mount to a non-empty mount point with fuse?

You need to make sure that the files on the device mounted by fuse will not have the same paths and file names as files which already existing in the nonempty mountpoint. Otherwise this would lead to confusion. If you are sure, pass -o nonempty to the mount command.

You can try what is happening using the following commands.. (Linux rocks!) .. without destroying anything..

// create 10 MB file 
dd if=/dev/zero of=partition bs=1024 count=10240

// create loopdevice from that file
sudo losetup /dev/loop0 ./partition

// create  filesystem on it
sudo e2mkfs.ext3 /dev/loop0

// mount the partition to temporary folder and create a file
mkdir test
sudo mount -o loop /dev/loop0 test
echo "bar" | sudo tee test/foo

# unmount the device
sudo umount /dev/loop0

# create the file again
echo "bar2" > test/foo

# now mount the device (having file with same name on it) 
# and see what happens
sudo mount -o loop /dev/loop0 test

delete all from table

This should be faster:

DELETE * FROM table_name;

because RDBMS don't have to look where is what.

You should be fine with truncate though:

truncate table table_name

How do I sort a Set to a List in Java?

There's no single method to do that. Use this:

@SuppressWarnings("unchecked")
public static <T extends Comparable> List<T> asSortedList(Collection<T> collection) {
  T[] array = collection.toArray(
    (T[])new Comparable[collection.size()]);
  Arrays.sort(array);
  return Arrays.asList(array);
}

Accessing an array out of bounds gives no error, why?

It's undefined behavior as far as I know. Run a larger program with that and it will crash somewhere along the way. Bounds checking is not a part of raw arrays (or even std::vector).

Use std::vector with std::vector::iterator's instead so you don't have to worry about it.

Edit:

Just for fun, run this and see how long until you crash:

int main()
{
   int array[1];

   for (int i = 0; i != 100000; i++)
   {
       array[i] = i;
   }

   return 0; //will be lucky to ever reach this
}

Edit2:

Don't run that.

Edit3:

OK, here is a quick lesson on arrays and their relationships with pointers:

When you use array indexing, you are really using a pointer in disguise (called a "reference"), that is automatically dereferenced. This is why instead of *(array[1]), array[1] automatically returns the value at that value.

When you have a pointer to an array, like this:

int array[5];
int *ptr = array;

Then the "array" in the second declaration is really decaying to a pointer to the first array. This is equivalent behavior to this:

int *ptr = &array[0];

When you try to access beyond what you allocated, you are really just using a pointer to other memory (which C++ won't complain about). Taking my example program above, that is equivalent to this:

int main()
{
   int array[1];
   int *ptr = array;

   for (int i = 0; i != 100000; i++, ptr++)
   {
       *ptr++ = i;
   }

   return 0; //will be lucky to ever reach this
}

The compiler won't complain because in programming, you often have to communicate with other programs, especially the operating system. This is done with pointers quite a bit.

OrderBy descending in Lambda expression?

Use System.Linq.Enumerable.OrderByDescending()?

For example:

var items = someEnumerable.OrderByDescending();

How do I include a JavaScript file in another JavaScript file?

Another way, that in my opinion is much cleaner, is to make a synchronous Ajax request instead of using a <script> tag. Which is also how Node.js handles includes.

Here's an example using jQuery:

function require(script) {
    $.ajax({
        url: script,
        dataType: "script",
        async: false,           // <-- This is the key
        success: function () {
            // all good...
        },
        error: function () {
            throw new Error("Could not load script " + script);
        }
    });
}

You can then use it in your code as you'd usually use an include:

require("/scripts/subscript.js");

And be able to call a function from the required script in the next line:

subscript.doSomethingCool(); 

How to use BeanUtils.copyProperties?

If you want to copy from searchContent to content, then code should be as follows

BeanUtils.copyProperties(content, searchContent);

You need to reverse the parameters as above in your code.

From API,

public static void copyProperties(Object dest, Object orig)
                           throws IllegalAccessException,
                                  InvocationTargetException)

Parameters:

dest - Destination bean whose properties are modified

orig - Origin bean whose properties are retrieved

jQuery issue - #<an Object> has no method

I had this problem, or one that looked superficially similar, yesterday. It turned out that I wasn't being careful when mixing jQuery and prototype. I found several solutions at http://docs.jquery.com/Using_jQuery_with_Other_Libraries. I opted for

var $j = jQuery.noConflict();

but there are other reasonable options described there.

Find all controls in WPF Window by type

Do note that using the VisualTreeHelper does only work on controls that derive from Visual or Visual3D. If you also need to inspect other elements (e.g. TextBlock, FlowDocument etc.), using VisualTreeHelper will throw an exception.

Here's an alternative that falls back to the logical tree if necessary:

http://www.hardcodet.net/2009/06/finding-elements-in-wpf-tree-both-ways

How to fire AJAX request Periodically?

Yes, you could use either the JavaScript setTimeout() method or setInterval() method to invoke the code that you would like to run. Here's how you might do it with setTimeout:

function executeQuery() {
  $.ajax({
    url: 'url/path/here',
    success: function(data) {
      // do something with the return value here if you like
    }
  });
  setTimeout(executeQuery, 5000); // you could choose not to continue on failure...
}

$(document).ready(function() {
  // run the first time; all subsequent calls will take care of themselves
  setTimeout(executeQuery, 5000);
});

Java POI : How to read Excel cell value and not the formula computing it?

For formula cells, excel stores two things. One is the Formula itself, the other is the "cached" value (the last value that the forumla was evaluated as)

If you want to get the last cached value (which may no longer be correct, but as long as Excel saved the file and you haven't changed it it should be), you'll want something like:

 for(Cell cell : row) {
     if(cell.getCellType() == Cell.CELL_TYPE_FORMULA) {
        System.out.println("Formula is " + cell.getCellFormula());
        switch(cell.getCachedFormulaResultType()) {
            case Cell.CELL_TYPE_NUMERIC:
                System.out.println("Last evaluated as: " + cell.getNumericCellValue());
                break;
            case Cell.CELL_TYPE_STRING:
                System.out.println("Last evaluated as \"" + cell.getRichStringCellValue() + "\"");
                break;
        }
     }
 }

How to remove all the null elements inside a generic list in one go?

You'll probably want the following.

List<EmailParameterClass> parameterList = new List<EmailParameterClass>{param1, param2, param3...};
parameterList.RemoveAll(item => item == null);

POST Multipart Form Data using Retrofit 2.0 including image

So its very simple way to achieve your task. You need to follow below step :-

1. First step

public interface APIService {  
    @Multipart
    @POST("upload")
    Call<ResponseBody> upload(
        @Part("item") RequestBody description,
        @Part("imageNumber") RequestBody description,
        @Part MultipartBody.Part imageFile
    );
}

You need to make the entire call as @Multipart request. item and image number is just string body which is wrapped in RequestBody. We use the MultipartBody.Part class that allows us to send the actual file name besides the binary file data with the request

2. Second step

  File file = (File) params[0];
  RequestBody requestFile = RequestBody.create(MediaType.parse("multipart/form-data"), file);

  MultipartBody.Part body =MultipartBody.Part.createFormData("Image", file.getName(), requestBody);

  RequestBody ItemId = RequestBody.create(okhttp3.MultipartBody.FORM, "22");
  RequestBody ImageNumber = RequestBody.create(okhttp3.MultipartBody.FORM,"1");
  final Call<UploadImageResponse> request = apiService.uploadItemImage(body, ItemId,ImageNumber);

Now you have image path and you need to convert into file.Now convert file into RequestBody using method RequestBody.create(MediaType.parse("multipart/form-data"), file). Now you need to convert your RequestBody requestFile into MultipartBody.Part using method MultipartBody.Part.createFormData("Image", file.getName(), requestBody); .

ImageNumber and ItemId is my another data which I need to send to server so I am also make both thing into RequestBody.

For more info

Angular 2 - Checking for server errors from subscribe

As stated in the relevant RxJS documentation, the .subscribe() method can take a third argument that is called on completion if there are no errors.

For reference:

  1. [onNext] (Function): Function to invoke for each element in the observable sequence.
  2. [onError] (Function): Function to invoke upon exceptional termination of the observable sequence.
  3. [onCompleted] (Function): Function to invoke upon graceful termination of the observable sequence.

Therefore you can handle your routing logic in the onCompleted callback since it will be called upon graceful termination (which implies that there won't be any errors when it is called).

this.httpService.makeRequest()
    .subscribe(
      result => {
        // Handle result
        console.log(result)
      },
      error => {
        this.errors = error;
      },
      () => {
        // 'onCompleted' callback.
        // No errors, route to new page here
      }
    );

As a side note, there is also a .finally() method which is called on completion regardless of the success/failure of the call. This may be helpful in scenarios where you always want to execute certain logic after an HTTP request regardless of the result (i.e., for logging purposes or for some UI interaction such as showing a modal).

Rx.Observable.prototype.finally(action)

Invokes a specified action after the source observable sequence terminates gracefully or exceptionally.

For instance, here is a basic example:

import { Observable } from 'rxjs/Rx';
import 'rxjs/add/operator/finally';

// ...

this.httpService.getRequest()
    .finally(() => {
      // Execute after graceful or exceptionally termination
      console.log('Handle logging logic...');
    })
    .subscribe (
      result => {
        // Handle result
        console.log(result)
      },
      error => {
        this.errors = error;
      },
      () => {
        // No errors, route to new page
      }
    );

Converting a date in MySQL from string field

SELECT STR_TO_DATE(dateString, '%d/%m/%y') FROM yourTable...

Why "no projects found to import"?

I have a perfect solution for this problem. After doing following simple steps you will be able to Import your source codes in Eclipse!


First of all, the reason why you can not Import your project into Eclipse workstation is that you do not have .project and .classpath file.

Now we know why this happens, so all we need to do is to create .project and .classpath file inside the project file. Here is how you do it:


First create .classpath file:

  1. create a new txt file and name it as .classpath
  2. copy paste following codes and save it:

    <?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" path="src"/> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/> <classpathentry kind="output" path="bin"/> </classpath>



Then create .project file:

  1. create a new txt file and name it as .project
  2. copy paste following codes:

    <?xml version="1.0" encoding="UTF-8"?> <projectDescription> <name>HereIsTheProjectName</name> <comment></comment> <projects> </projects> <buildSpec> <buildCommand> <name>org.eclipse.jdt.core.javabuilder</name> <arguments> </arguments> </buildCommand> </buildSpec> <natures> <nature>org.eclipse.jdt.core.javanature</nature> </natures> </projectDescription>

  3. you have to change the name field to your project name. you can do this in line 3 by changing HereIsTheProjectName to your own project name. then save it.


That is all, Enjoy!!

List of IP Space used by Facebook

The list from 2020-05-23 is:

31.13.24.0/21
31.13.64.0/18
45.64.40.0/22
66.220.144.0/20
69.63.176.0/20
69.171.224.0/19
74.119.76.0/22
102.132.96.0/20
103.4.96.0/22
129.134.0.0/16
147.75.208.0/20
157.240.0.0/16
173.252.64.0/18
179.60.192.0/22
185.60.216.0/22
185.89.216.0/22
199.201.64.0/22
204.15.20.0/22

The method to fetch this list is already documented on Facebook's Developer site, you can make a whois call to see all IPs assigned to Facebook:

whois -h whois.radb.net -- '-i origin AS32934' | grep ^route

Most efficient way to check for DBNull and then assign to a variable?

I personally favour this syntax, which uses the explicit IsDbNull method exposed by IDataRecord, and caches the column index to avoid a duplicate string lookup.

Expanded for readability, it goes something like:

int columnIndex = row.GetOrdinal("Foo");
string foo; // the variable we're assigning based on the column value.
if (row.IsDBNull(columnIndex)) {
  foo = String.Empty; // or whatever
} else { 
  foo = row.GetString(columnIndex);
}

Rewritten to fit on a single line for compactness in DAL code - note that in this example we're assigning int bar = -1 if row["Bar"] is null.

int i; // can be reused for every field.
string foo  = (row.IsDBNull(i  = row.GetOrdinal("Foo")) ? null : row.GetString(i));
int bar = (row.IsDbNull(i = row.GetOrdinal("Bar")) ? -1 : row.GetInt32(i));

The inline assignment can be confusing if you don't know it's there, but it keeps the entire operation on one line, which I think enhances readability when you're populating properties from multiple columns in one block of code.

"X-UA-Compatible" content="IE=9; IE=8; IE=7; IE=EDGE"

In certain cases, it might be necessary to restrict the display of a webpage to a document mode supported by an earlier version of Internet Explorer. You can do this by serving the page with an x-ua-compatible header. For more info, see Specifying legacy document modes.
- https://msdn.microsoft.com/library/cc288325

Thus this tag is used to future proof the webpage, such that the older / compatible engine is used to render it the same way as intended by the creator.

Make sure that you have checked it to work properly with the IE version you specify.

Using Javascript in CSS

Not in any conventional sense of the phrase "inside CSS."

Disabled form fields not submitting data

As it was already mentioned: READONLY does not work for <input type='checkbox'> and <select>...</select>.

If you have a Form with disabled checkboxes / selects AND need them to be submitted, you can use jQuery:

$('form').submit(function(e) {
    $(':disabled').each(function(e) {
        $(this).removeAttr('disabled');
    })
});

This code removes the disabled attribute from all elements on submit.

How to Insert BOOL Value to MySQL Database

TRUE and FALSE are keywords, and should not be quoted as strings:

INSERT INTO first VALUES (NULL, 'G22', TRUE);
INSERT INTO first VALUES (NULL, 'G23', FALSE);

By quoting them as strings, MySQL will then cast them to their integer equivalent (since booleans are really just a one-byte INT in MySQL), which translates into zero for any non-numeric string. Thus, you get 0 for both values in your table.

Non-numeric strings cast to zero:

mysql> SELECT CAST('TRUE' AS SIGNED), CAST('FALSE' AS SIGNED), CAST('12345' AS SIGNED);
+------------------------+-------------------------+-------------------------+
| CAST('TRUE' AS SIGNED) | CAST('FALSE' AS SIGNED) | CAST('12345' AS SIGNED) |
+------------------------+-------------------------+-------------------------+
|                      0 |                       0 |                   12345 |
+------------------------+-------------------------+-------------------------+

But the keywords return their corresponding INT representation:

mysql> SELECT TRUE, FALSE;
+------+-------+
| TRUE | FALSE |
+------+-------+
|    1 |     0 |
+------+-------+

Note also, that I have replaced your double-quotes with single quotes as are more standard SQL string enclosures. Finally, I have replaced your empty strings for id with NULL. The empty string may issue a warning.

How to use concerns in Rails 4

I felt most of the examples here demonstrated the power of module rather than how ActiveSupport::Concern adds value to module.

Example 1: More readable modules.

So without concerns this how a typical module will be.

module M
  def self.included(base)
    base.extend ClassMethods
    base.class_eval do
      scope :disabled, -> { where(disabled: true) }
    end
  end

  def instance_method
    ...
  end

  module ClassMethods
    ...
  end
end

After refactoring with ActiveSupport::Concern.

require 'active_support/concern'

module M
  extend ActiveSupport::Concern

  included do
    scope :disabled, -> { where(disabled: true) }
  end

  class_methods do
    ...
  end

  def instance_method
    ...
  end
end

You see instance methods, class methods and included block are less messy. Concerns will inject them appropriately for you. That's one advantage of using ActiveSupport::Concern.


Example 2: Handle module dependencies gracefully.

module Foo
  def self.included(base)
    base.class_eval do
      def self.method_injected_by_foo_to_host_klass
        ...
      end
    end
  end
end

module Bar
  def self.included(base)
    base.method_injected_by_foo_to_host_klass
  end
end

class Host
  include Foo # We need to include this dependency for Bar
  include Bar # Bar is the module that Host really needs
end

In this example Bar is the module that Host really needs. But since Bar has dependency with Foo the Host class have to include Foo (but wait why does Host want to know about Foo? Can it be avoided?).

So Bar adds dependency everywhere it goes. And order of inclusion also matters here. This adds lot of complexity/dependency to huge code base.

After refactoring with ActiveSupport::Concern

require 'active_support/concern'

module Foo
  extend ActiveSupport::Concern
  included do
    def self.method_injected_by_foo_to_host_klass
      ...
    end
  end
end

module Bar
  extend ActiveSupport::Concern
  include Foo

  included do
    self.method_injected_by_foo_to_host_klass
  end
end

class Host
  include Bar # It works, now Bar takes care of its dependencies
end

Now it looks simple.

If you are thinking why can't we add Foo dependency in Bar module itself? That won't work since method_injected_by_foo_to_host_klass have to be injected in a class that's including Bar not on Bar module itself.

Source: Rails ActiveSupport::Concern

Freeze the top row for an html table only (Fixed Table Header Scrolling)

Using css zebra styling

Copy paste this example and see the header fixed.

       <style>
       .zebra tr:nth-child(odd){
       background:white;
       color:black;
       }

       .zebra tr:nth-child(even){
       background: grey;
       color:black;
       }

      .zebra tr:nth-child(1) {
       background:black;
       color:yellow;
       position: fixed;
       margin:-30px 0px 0px 0px;
       }
       </style>


   <DIV  id= "stripped_div"

         class= "zebra"
         style = "
            border:solid 1px red;
            height:15px;
            width:200px;
            overflow-x:none;
            overflow-y:scroll;
            padding:30px 0px 0px 0px;"
            >

                <table>
                   <tr >
                       <td>Name:</td>
                       <td>Age:</td>
                   </tr>
                    <tr >
                       <td>Peter</td>
                       <td>10</td>
                   </tr>
                </table>

    </DIV>

Notice the top padding of of 30px in the div leaves space that is utilized by the 1st row of stripped data ie tr:nth-child(1) that is "fixed position" and formatted to a margin of -30px

Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.9.4 or earlier

Update

data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.


You can use DT[order(-rank(x), y)].

   x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6

How do I create a chart with multiple series using different X values for each series?

You need to use the Scatter chart type instead of Line. That will allow you to define separate X values for each series.

How to upload a file and JSON data in Postman?

If you are using cookies to keep session, you can use interceptor to share cookies from browser to postman.

Also to upload a file you can use form-data tab under body tab on postman, In which you can provide data in key-value format and for each key you can select the type of value text/file. when you select file type option appeared to upload the file.

Git on Windows: How do you set up a mergetool?

As already answered here (and here and here), mergetool is the command to configure this. For a nice graphical frontend I recommend kdiff3 (GPL).

Batch script to find and replace a string in text file without creating an extra output file for storing the modified file

@echo off 
    setlocal enableextensions disabledelayedexpansion

    set "search=%1"
    set "replace=%2"

    set "textFile=Input.txt"

    for /f "delims=" %%i in ('type "%textFile%" ^& break ^> "%textFile%" ') do (
        set "line=%%i"
        setlocal enabledelayedexpansion
        >>"%textFile%" echo(!line:%search%=%replace%!
        endlocal
    )

for /f will read all the data (generated by the type comamnd) before starting to process it. In the subprocess started to execute the type, we include a redirection overwritting the file (so it is emptied). Once the do clause starts to execute (the content of the file is in memory to be processed) the output is appended to the file.

What is mapDispatchToProps?

mapStateToProps receives the state and props and allows you to extract props from the state to pass to the component.

mapDispatchToProps receives dispatch and props and is meant for you to bind action creators to dispatch so when you execute the resulting function the action gets dispatched.

I find this only saves you from having to do dispatch(actionCreator()) within your component thus making it a bit easier to read.

https://github.com/reactjs/react-redux/blob/master/docs/api.md#arguments

using setTimeout on promise chain

To keep the promise chain going, you can't use setTimeout() the way you did because you aren't returning a promise from the .then() handler - you're returning it from the setTimeout() callback which does you no good.

Instead, you can make a simple little delay function like this:

function delay(t, v) {
   return new Promise(function(resolve) { 
       setTimeout(resolve.bind(null, v), t)
   });
}

And, then use it like this:

getLinks('links.txt').then(function(links){
    let all_links = (JSON.parse(links));
    globalObj=all_links;

    return getLinks(globalObj["one"]+".txt");

}).then(function(topic){
    writeToBody(topic);
    // return a promise here that will be chained to prior promise
    return delay(1000).then(function() {
        return getLinks(globalObj["two"]+".txt");
    });
});

Here you're returning a promise from the .then() handler and thus it is chained appropriately.


You can also add a delay method to the Promise object and then directly use a .delay(x) method on your promises like this:

_x000D_
_x000D_
function delay(t, v) {_x000D_
   return new Promise(function(resolve) { _x000D_
       setTimeout(resolve.bind(null, v), t)_x000D_
   });_x000D_
}_x000D_
_x000D_
Promise.prototype.delay = function(t) {_x000D_
    return this.then(function(v) {_x000D_
        return delay(t, v);_x000D_
    });_x000D_
}_x000D_
_x000D_
_x000D_
Promise.resolve("hello").delay(500).then(function(v) {_x000D_
    console.log(v);_x000D_
});
_x000D_
_x000D_
_x000D_

Or, use the Bluebird promise library which already has the .delay() method built-in.

ORA-00932: inconsistent datatypes: expected - got CLOB

Take a substr of the CLOB and then convert it to a char:

UPDATE IMS_TEST 
  SET TEST_Category           = 'just testing' 
WHERE to_char(substr(TEST_SCRIPT, 1, 9))    = 'something'
  AND ID                      = '10000239';

Use jQuery to hide a DIV when the user clicks outside of it

Built off of prc322's awesome answer.

function hideContainerOnMouseClickOut(selector, callback) {
  var args = Array.prototype.slice.call(arguments); // Save/convert arguments to array since we won't be able to access these within .on()
  $(document).on("mouseup.clickOFF touchend.clickOFF", function (e) {
    var container = $(selector);

    if (!container.is(e.target) // if the target of the click isn't the container...
        && container.has(e.target).length === 0) // ... nor a descendant of the container
    {
      container.hide();
      $(document).off("mouseup.clickOFF touchend.clickOFF");
      if (callback) callback.apply(this, args);
    }
  });
}

This adds a couple things...

  1. Placed within a function with a callback with "unlimited" args
  2. Added a call to jquery's .off() paired with a event namespace to unbind the event from the document once it's been run.
  3. Included touchend for mobile functionality

I hope this helps someone!

Swift do-try-catch syntax

There are two important points to the Swift 2 error handling model: exhaustiveness and resiliency. Together, they boil down to your do/catch statement needing to catch every possible error, not just the ones you know you can throw.

Notice that you don't declare what types of errors a function can throw, only whether it throws at all. It's a zero-one-infinity sort of problem: as someone defining a function for others (including your future self) to use, you don't want to have to make every client of your function adapt to every change in the implementation of your function, including what errors it can throw. You want code that calls your function to be resilient to such change.

Because your function can't say what kind of errors it throws (or might throw in the future), the catch blocks that catch it errors don't know what types of errors it might throw. So, in addition to handling the error types you know about, you need to handle the ones you don't with a universal catch statement -- that way if your function changes the set of errors it throws in the future, callers will still catch its errors.

do {
    let sandwich = try makeMeSandwich(kitchen)
    print("i eat it \(sandwich)")
} catch SandwichError.NotMe {
    print("Not me error")
} catch SandwichError.DoItYourself {
    print("do it error")
} catch let error {
    print(error.localizedDescription)
}

But let's not stop there. Think about this resilience idea some more. The way you've designed your sandwich, you have to describe errors in every place where you use them. That means that whenever you change the set of error cases, you have to change every place that uses them... not very fun.

The idea behind defining your own error types is to let you centralize things like that. You could define a description method for your errors:

extension SandwichError: CustomStringConvertible {
    var description: String {
        switch self {
            case NotMe: return "Not me error"
            case DoItYourself: return "Try sudo"
        }
    }
}

And then your error handling code can ask your error type to describe itself -- now every place where you handle errors can use the same code, and handle possible future error cases, too.

do {
    let sandwich = try makeMeSandwich(kitchen)
    print("i eat it \(sandwich)")
} catch let error as SandwichError {
    print(error.description)
} catch {
    print("i dunno")
}

This also paves the way for error types (or extensions on them) to support other ways of reporting errors -- for example, you could have an extension on your error type that knows how to present a UIAlertController for reporting the error to an iOS user.

No module named _sqlite3

I had the same problem with Python 3.5 on Ubuntu while using pyenv.

If you're installing the python using pyenv, it's listed as one of the common build problems. To solve it, remove the installed python version, install the requirements (for this particular case libsqlite3-dev), then reinstall the python version.

Checkout one file from Subversion

Go to the repo-browser right-click the file and use 'Save As', I'm using TortoiseSVN though.

Transparent background in JPEG image

Just wanted to add that GIF "transparency" is more like missing pixels. If you use GIF then you will see jagged edges where the background and the rest of the image meet. Using PNG, you can smoothly "composite" images together, which is what you really want. Plus PNG supports highly quality images.

Don't use "Paint". There are many high quality art applications for doing art work. I think even the cell phone apps (Pixlr is pretty good and free!) and web-based image editting apps are better. I use Gimp - free for all platforms.

While a JPEG can't be made transparent in and of itself, if your goal is to reduce the size of very large image areas for the web that need to contain transparent image areas, then there is a solution. It's a bit too complicated to post details, but Google it. Basically, you create your image with transparency and then split out the alpha channel (Gimp can do this easily) as a simple 8-bit greyscale PNG. Then you export the color data as a JPG. Now your web page uses a CANVAS tag to load the JPG as image data and applies the 8-bit greyscale PNG as the Canvas's alpha channel. The browser's Canvas does the work of making the image transparent. The JPEG stores the color info (better compressed than PNG) and the PNG is reduced to 8-bit alpha so its considerably smaller. I've saved a few hundred K per image using this technique. A few people have proposed file formats that embed PNG transparency info into a JPEG's extended information fields, but these proposal's don't have wide support as of yet.

Adding an onclick function to go to url in JavaScript?

If you would like to open link in a new tab, you can:

$("a#thing_to_click").on('click',function(){
    window.open('https://yoururl.com', '_blank');
});

Android Firebase, simply get one child object's data

just fetch specific node data and its working perfect for me

mFirebaseInstance.getReference("yourNodeName").getRef().addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {


        for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
            Log.e(TAG, "======="+postSnapshot.child("email").getValue());
            Log.e(TAG, "======="+postSnapshot.child("name").getValue());
        }
    }

    @Override
    public void onCancelled(DatabaseError error) {
        // Failed to read value
        Log.e(TAG, "Failed to read app title value.", error.toException());
    }
});

How to link to part of the same document in Markdown?

yes, markdown does do this but you need to specify the name anchor <a name='xyx'>.

a full example,

this creates the link
[tasks](#tasks)

later in the document, you create the named anchor (whatever it is called).

<a name="tasks">
   my tasks
</a>

note that you could also wrap it around the header too.

<a name="tasks">
### Agile tasks (created by developer)
</a>

django order_by query set, ascending and descending

  1. Ascending order

    Reserved.objects.all().filter(client=client_id).order_by('check_in')
    
  2. Descending order

    Reserved.objects.all().filter(client=client_id).order_by('-check_in')
    

- (hyphen) is used to indicate descending order here.

Why can't DateTime.Parse parse UTC date

or use the AdjustToUniversal DateTimeStyle in a call to

DateTime.ParseExact(String, String[], IFormatProvider, DateTimeStyles)

how to change class name of an element by jquery

Instead of removeClass and addClass, you can also do it like this:

$('.IsBestAnswer').toggleClass('IsBestAnswer bestanswer');

subquery in FROM must have an alias

add an ALIAS on the subquery,

SELECT  COUNT(made_only_recharge) AS made_only_recharge
FROM    
    (
        SELECT DISTINCT (identifiant) AS made_only_recharge
        FROM cdr_data
        WHERE CALLEDNUMBER = '0130'
        EXCEPT
        SELECT DISTINCT (identifiant) AS made_only_recharge
        FROM cdr_data
        WHERE CALLEDNUMBER != '0130'
    ) AS derivedTable                           -- <<== HERE

How to make --no-ri --no-rdoc the default for gem install?

A oneliner for the windows 7 users:

(echo install: --no-document && echo update: --no-document) >> c:\ProgramData\gemrc

How to make Apache serve index.php instead of index.html?

As of today (2015, Aug., 1st), Apache2 in Debian Jessie, you need to edit:

root@host:/etc/apache2/mods-enabled$ vi dir.conf 

And change the order of that line, bringing index.php to the first position:

DirectoryIndex index.php index.html index.cgi index.pl index.xhtml index.htm

Navigate to another page with a button in angular 2

Having the router link on the button seems to work fine for me:

<button class="nav-link" routerLink="/" (click)="hideMenu()">
     <i class="fa fa-home"></i> 
     <span>Home</span>
</button>

How to invoke a Linux shell command from Java

exec does not execute a command in your shell

try

Process p = Runtime.getRuntime().exec(new String[]{"csh","-c","cat /home/narek/pk.txt"});

instead.

EDIT:: I don't have csh on my system so I used bash instead. The following worked for me

Process p = Runtime.getRuntime().exec(new String[]{"bash","-c","ls /home/XXX"});

Android get image path from drawable as string

These all are ways:

String imageUri = "drawable://" + R.drawable.image;

Other ways I tested

Uri path = Uri.parse("android.resource://com.segf4ult.test/" + R.drawable.icon);
Uri otherPath = Uri.parse("android.resource://com.segf4ult.test/drawable/icon");

String path = path.toString();
String path = otherPath .toString();

jQuery autocomplete tagging plug-in like StackOverflow's input tags?

This originally answered a supplemental question about the wisdom of downloading jQuery versus accessing it via a CDN, which is no longer present...

To answer the thing about Google. I have moved over to accessing JQuery and most other of these sorts of libraries via the corresponding CDN in my sites.

As more people do this means that it's more likely to be cached on user's machines, so my vote goes for good idea.

In the five years since I first offered this, it has become common wisdom.

Swift programmatically navigate to another view controller/scene

SWIFT 4.x

The Strings in double quotes always confuse me, so I think answer to this question needs some graphical presentation to clear this out.

For a banking app, I have a LoginViewController and a BalanceViewController. Each have their respective screens.

The app starts and shows the Login screen. When login is successful, app opens the Balance screen.

Here is how it looks:

enter image description here

enter image description here

The login success is handled like this:

let storyBoard: UIStoryboard = UIStoryboard(name: "Balance", bundle: nil)
let balanceViewController = storyBoard.instantiateViewController(withIdentifier: "balance") as! BalanceViewController
self.present(balanceViewController, animated: true, completion: nil)

As you can see, the storyboard ID 'balance' in small letters is what goes in the second line of the code, and this is the ID which is defined in the storyboard settings, as in the attached screenshot.

The term 'Balance' with capital 'B' is the name of the storyboard file, which is used in the first line of the code.

We know that using hard coded Strings in code is a very bad practice, but somehow in iOS development it has become a common practice, and Xcode doesn't even warn about them.

MySQL - UPDATE query with LIMIT

For people get this post by search "update limit MySQL" trying to avoid turning off the safe update mode when facing update with the multiple-table syntax.

Since the offical document state

For the multiple-table syntax, UPDATE updates rows in each table named in table_references that satisfy the conditions. In this case, ORDER BY and LIMIT cannot be used.

https://stackoverflow.com/a/28316067/1278112
I think this answer is quite helpful. It gives an example

UPDATE customers SET countryCode = 'USA' WHERE country = 'USA'; -- which gives the error, you just write:

UPDATE customers SET countryCode = 'USA' WHERE (country = 'USA' AND customerNumber <> 0); -- Because customerNumber is a primary key you got no error 1175 any more.

What I want but would raise error code 1175.

UPDATE table1 t1
        INNER JOIN
    table2 t2 ON t1.name = t2.name 
SET 
    t1.column = t2.column
WHERE
    t1.name = t2.name;

The working edition

UPDATE table1 t1
        INNER JOIN
    table2 t2 ON t1.name = t2.name 
SET 
    t1.column = t2.column
WHERE
    (t1.name = t2.name and t1.prime_key !=0);

Which is really simple and elegant. Since the original answer doesn't get too much attention (votes), I post more explanation. Hope this can help others.

Run reg command in cmd (bat file)?

You could also just create a Group Policy Preference and have it create the reg key for you. (no scripting involved)

"git rebase origin" vs."git rebase origin/master"

You can make a new file under [.git\refs\remotes\origin] with name "HEAD" and put content "ref: refs/remotes/origin/master" to it. This should solve your problem.

It seems that clone from an empty repos will lead to this. Maybe the empty repos do not have HEAD because no commit object exist.

You can use the

git log --remotes --branches --oneline --decorate

to see the difference between each repository, while the "problem" one do not have "origin/HEAD"

Edit: Give a way using command line
You can also use git command line to do this, they have the same result

git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/master

How to make HTML open a hyperlink in another window or tab?

The target attribute is your best way of doing this.

<a href="http://www.starfall.com" target="_blank">

will open it in a new tab or window. As for which, it depends on the users settings.

<a href="http://www.starfall.com" target="_self">

is default. It makes the page open in the same tab (or iframe, if that's what you're dealing with).
The next two are only good if you're dealing with an iframe.

<a href="http://www.starfall.com" target="_parent">

will open the link in the iframe that the iframe that had the link was in.

<a href="http://www.starfall.com" target="_top">

will open the link in the tab, no matter how many iframes it has to go through.

MongoDB what are the default user and password?

By default mongodb has no enabled access control, so there is no default user or password.

To enable access control, use either the command line option --auth or security.authorization configuration file setting.

You can use the following procedure or refer to Enabling Auth in the MongoDB docs.

Procedure

  1. Start MongoDB without access control.

    mongod --port 27017 --dbpath /data/db1
    
  2. Connect to the instance.

    mongo --port 27017
    
  3. Create the user administrator.

    use admin
    db.createUser(
      {
        user: "myUserAdmin",
        pwd: "abc123",
        roles: [ { role: "userAdminAnyDatabase", db: "admin" } ]
      }
    )
    
  4. Re-start the MongoDB instance with access control.

    mongod --auth --port 27017 --dbpath /data/db1
    
  5. Authenticate as the user administrator.

    mongo --port 27017 -u "myUserAdmin" -p "abc123" \
      --authenticationDatabase "admin"
    

How does bitshifting work in Java?

byte x = 51; //00101011
byte y = (byte) (x >> 2); //00001010 aka Base(10) 10

mySQL :: insert into table, data from another table?

INSERT INTO preliminary_image (style_id,pre_image_status,file_extension,reviewer_id,
uploader_id,is_deleted,last_updated) 

SELECT '4827499',pre_image_status,file_extension,reviewer_id,
uploader_id,'0',last_updated FROM preliminary_image WHERE style_id=4827488

Analysis

We can use above query if we want to copy data from one table to another table in mysql

  1. Here source and destination table are same, we can use different tables also.
  2. Few columns we are not copying like style_id and is_deleted so we selected them hard coded from another table
  3. Table we used in source also contains auto increment field so we left that column and it get inserted automatically with execution of query.

Execution results

1 queries executed, 1 success, 0 errors, 0 warnings

Query: insert into preliminary_image (style_id,pre_image_status,file_extension,reviewer_id,uploader_id,is_deleted,last_updated) select ...

5 row(s) affected

Execution Time : 0.385 sec Transfer Time : 0 sec Total Time : 0.386 sec

Maximum number of records in a MySQL database table

mysql int types can do quite a few rows: http://dev.mysql.com/doc/refman/5.0/en/numeric-types.html

unsigned int largest value is 4,294,967,295
unsigned bigint largest value is 18,446,744,073,709,551,615

Creating a search form in PHP to search a database?

try this out let me know what happens.

Form:

<form action="form.php" method="post"> 
Search: <input type="text" name="term" /><br /> 
<input type="submit" value="Submit" /> 
</form> 

Form.php:

$term = mysql_real_escape_string($_REQUEST['term']);    

$sql = "SELECT * FROM liam WHERE Description LIKE '%".$term."%'";
$r_query = mysql_query($sql);

while ($row = mysql_fetch_array($r_query)){ 
echo 'Primary key: ' .$row['PRIMARYKEY']; 
echo '<br /> Code: ' .$row['Code']; 
echo '<br /> Description: '.$row['Description']; 
echo '<br /> Category: '.$row['Category']; 
echo '<br /> Cut Size: '.$row['CutSize'];  
} 

Edit: Cleaned it up a little more.

Final Cut (my test file):

<?php
$db_hostname = 'localhost';
$db_username = 'demo';
$db_password = 'demo';
$db_database = 'demo';

// Database Connection String
$con = mysql_connect($db_hostname,$db_username,$db_password);
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db($db_database, $con);
?>

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title></title>
    </head>
    <body>
<form action="" method="post">  
Search: <input type="text" name="term" /><br />  
<input type="submit" value="Submit" />  
</form>  
<?php
if (!empty($_REQUEST['term'])) {

$term = mysql_real_escape_string($_REQUEST['term']);     

$sql = "SELECT * FROM liam WHERE Description LIKE '%".$term."%'"; 
$r_query = mysql_query($sql); 

while ($row = mysql_fetch_array($r_query)){  
echo 'Primary key: ' .$row['PRIMARYKEY'];  
echo '<br /> Code: ' .$row['Code'];  
echo '<br /> Description: '.$row['Description'];  
echo '<br /> Category: '.$row['Category'];  
echo '<br /> Cut Size: '.$row['CutSize'];   
}  

}
?>
    </body>
</html>

How to switch databases in psql?

  Connect to database:

  Method 1 : enter to db : sudo -u postgres psql

  Connect to db : \c dbname

  Method 2 : directly connect to db : sudo -u postgres psql -d my_database_name

LogCat message: The Google Play services resources were not found. Check your project configuration to ensure that the resources are included

I had the same issue here. As Magnus said above, for me it was happening due to an SDK update to version 22.0.5.

After performing a full update in my Android SDK (including Google Play Services) and Android plugins in Eclipse, I was able to use play services lib in my application.

How do I change the background color with JavaScript?

AJAX is getting data from the server using Javascript and XML in an asynchronous fashion. Unless you want to download the colour code from the server, that's not what you're really aiming for!

But otherwise you can set the CSS background with Javascript. If you're using a framework like jQuery, it'll be something like this:

$('body').css('background', '#ccc');

Otherwise, this should work:

document.body.style.background = "#ccc";

What is the most robust way to force a UIView to redraw?

I had a problem with a big delay between calling setNeedsDisplay and drawRect: (5 seconds). It turned out I called setNeedsDisplay in a different thread than the main thread. After moving this call to the main thread the delay went away.

Hope this is of some help.

How can I read a text file in Android?

Try this :

I assume your text file is on sd card

    //Find the directory for the SD Card using the API
//*Don't* hardcode "/sdcard"
File sdcard = Environment.getExternalStorageDirectory();

//Get the text file
File file = new File(sdcard,"file.txt");

//Read text from file
StringBuilder text = new StringBuilder();

try {
    BufferedReader br = new BufferedReader(new FileReader(file));
    String line;

    while ((line = br.readLine()) != null) {
        text.append(line);
        text.append('\n');
    }
    br.close();
}
catch (IOException e) {
    //You'll need to add proper error handling here
}

//Find the view by its id
TextView tv = (TextView)findViewById(R.id.text_view);

//Set the text
tv.setText(text.toString());

following links can also help you :

How can I read a text file from the SD card in Android?

How to read text file in Android?

Android read text raw resource file

Can I Set "android:layout_below" at Runtime Programmatically?

While @jackofallcode answer is correct, it can be written in one line:

((RelativeLayout.LayoutParams) viewToLayout.getLayoutParams()).addRule(RelativeLayout.BELOW, R.id.below_id);

How can I add an item to a IEnumerable<T> collection?

No, the IEnumerable doesn't support adding items to it.

Your 'alternative' is:

var myList = new List(items);
myList.Add(otherItem);

Get Substring - everything before certain char

Building on BrainCore's answer:

    int index = 0;   
    str = "223232-1.jpg";

    //Assuming we trust str isn't null 
    if (str.Contains('-') == "true")
    {
      int index = str.IndexOf('-');
    }

    if(index > 0) {
        return str.Substring(0, index);
    }
    else {
       return str;
    }

How do I create a new line in Javascript?

Use a <br> tag to create a line break in the document

document.write("<br>");

Here's a sample fiddle

Angularjs - simple form submit

I think the reason AngularJS does not say much about form submission because it depends more on 'two-way data binding'. In traditional html development you had one way data binding, i.e. once DOM rendered any changes you make to DOM element did not reflect in JS Object, however in AngularJS it works both way. Hence there's in fact no need to form submission. I have done a mid sized application using AngularJS without the need to form submission. If you are keen to submit form you can write a directive wrapping up your form which handles ENTER keydown and SUBMIT button click events and call form.submit().

If you want the sample source code of such a directive, please let me know by commenting on this. I figured out it would a simple directive that you can write yourself.

Use .corr to get the correlation between two columns

changing 'Citable docs per Capita' to numeric before correlation will solve the problem.

    Top15['Citable docs per Capita'] = pd.to_numeric(Top15['Citable docs per Capita'])
    data = Top15[['Citable docs per Capita','Energy Supply per Capita']]
    correlation = data.corr(method='pearson')

Calculate the display width of a string in Java

Use the getWidth method in the following class:

import java.awt.*;
import java.awt.geom.*;
import java.awt.font.*;

class StringMetrics {

  Font font;
  FontRenderContext context;

  public StringMetrics(Graphics2D g2) {

    font = g2.getFont();
    context = g2.getFontRenderContext();
  }

  Rectangle2D getBounds(String message) {

    return font.getStringBounds(message, context);
  }

  double getWidth(String message) {

    Rectangle2D bounds = getBounds(message);
    return bounds.getWidth();
  }

  double getHeight(String message) {

    Rectangle2D bounds = getBounds(message);
    return bounds.getHeight();
  }

}

How do I display the current value of an Android Preference in the Preference summary?

There are ways to make this a more generic solution, if that suits your needs.

For example, if you want to generically have all list preferences show their choice as summary, you could have this for your onSharedPreferenceChanged implementation:

public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
    Preference pref = findPreference(key);

    if (pref instanceof ListPreference) {
        ListPreference listPref = (ListPreference) pref;
        pref.setSummary(listPref.getEntry());
    }
}

This is easily extensible to other preference classes.

And by using the getPreferenceCount and getPreference functionality in PreferenceScreen and PreferenceCategory, you could easily write a generic function to walk the preference tree setting the summaries of all preferences of the types you desire to their toString representation

How to cherry pick a range of commits and merge into another branch?

As of git v1.7.2 cherry pick can accept a range of commits:

git cherry-pick learned to pick a range of commits (e.g. cherry-pick A..B and cherry-pick --stdin), so did git revert; these do not support the nicer sequencing control rebase [-i] has, though.

Why does 2 mod 4 = 2?

2 / 4 = 0 with a remainder of 2

Why doesn't JavaScript support multithreading?

Javascript is a single-threaded language. This means it has one call stack and one memory heap. As expected, it executes code in order and must finish executing a piece code before moving onto the next. It's synchronous, but at times that can be harmful. For example, if a function takes a while to execute or has to wait on something, it freezes everything up in the meanwhile.

How to create new folder?

You probably want os.makedirs as it will create intermediate directories as well, if needed.

import os

#dir is not keyword
def makemydir(whatever):
  try:
    os.makedirs(whatever)
  except OSError:
    pass
  # let exception propagate if we just can't
  # cd into the specified directory
  os.chdir(whatever)

Bash: Echoing a echo command with a variable in bash

You just need to use single quotes:

$ echo "$TEST"
test
$ echo '$TEST'
$TEST

Inside single quotes special characters are not special any more, they are just normal characters.

Remove an onclick listener

Setting setOnClickListener(null) is a good idea to remove click listener at runtime.

And also someone commented that calling View.hasOnClickListeners() after this will return true, NO my friend.

Here is the implementation of hasOnClickListeners() taken from android.view.View class

 public boolean hasOnClickListeners() {
        ListenerInfo li = mListenerInfo;
        return (li != null && li.mOnClickListener != null);
    }

Thank GOD. It checks for null.

So everything is safe. Enjoy :-)

How to scp in Python?

Hmmm, perhaps another option would be to use something like sshfs (there an sshfs for Mac too). Once your router is mounted you can just copy the files outright. I'm not sure if that works for your particular application but it's a nice solution to keep handy.

How to download all dependencies and packages to directory

Same question already answered here: How to list/download the recursive dependencies of a debian package?

try:

PACKAGES="wget unzip"
apt-get download $(apt-cache depends --recurse --no-recommends --no-suggests \
  --no-conflicts --no-breaks --no-replaces --no-enhances \
  --no-pre-depends ${PACKAGES} | grep "^\w")

Relationship between hashCode and equals method in Java

The contract is that if obj1.equals(obj2) then obj1.hashCode() == obj2.hashCode() , it is mainly for performance reasons, as maps are mainly using hashCode method to compare entries keys.

Android SDK Manager gives "Failed to fetch URL https://dl-ssl.google.com/android/repository/repository.xml" error when selecting repository

I found another way without setting proxy. I'm currently using an antivirus which has a firewall program. Then, I turn off this firewall and now I can fetch that URL.

If still doesn't work, try to turn off Firewall on your PC, such as Windows Firewall.

cast or convert a float to nvarchar?

For anyone willing to try a different method, they can use this:

select FORMAT([Column_Name], '') from YourTable

This will easily change any float value to nvarchar.

Managing large binary files with Git

The solution I'd like to propose is based on orphan branches and a slight abuse of the tag mechanism, henceforth referred to as *Orphan Tags Binary Storage (OTABS)

TL;DR 12-01-2017 If you can use github's LFS or some other 3rd party, by all means you should. If you can't, then read on. Be warned, this solution is a hack and should be treated as such.

Desirable properties of OTABS

  • it is a pure git and git only solution -- it gets the job done without any 3rd party software (like git-annex) or 3rd party infrastructure (like github's LFS).
  • it stores the binary files efficiently, i.e. it doesn't bloat the history of your repository.
  • git pull and git fetch, including git fetch --all are still bandwidth efficient, i.e. not all large binaries are pulled from the remote by default.
  • it works on Windows.
  • it stores everything in a single git repository.
  • it allows for deletion of outdated binaries (unlike bup).

Undesirable properties of OTABS

  • it makes git clone potentially inefficient (but not necessarily, depending on your usage). If you deploy this solution you might have to advice your colleagues to use git clone -b master --single-branch <url> instead of git clone. This is because git clone by default literally clones entire repository, including things you wouldn't normally want to waste your bandwidth on, like unreferenced commits. Taken from SO 4811434.
  • it makes git fetch <remote> --tags bandwidth inefficient, but not necessarily storage inefficient. You can can always advise your colleagues not to use it.
  • you'll have to periodically use a git gc trick to clean your repository from any files you don't want any more.
  • it is not as efficient as bup or git-bigfiles. But it's respectively more suitable for what you're trying to do and more off-the-shelf. You are likely to run into trouble with hundreds of thousands of small files or with files in range of gigabytes, but read on for workarounds.

Adding the Binary Files

Before you start make sure that you've committed all your changes, your working tree is up to date and your index doesn't contain any uncommitted changes. It might be a good idea to push all your local branches to your remote (github etc.) in case any disaster should happen.

  1. Create a new orphan branch. git checkout --orphan binaryStuff will do the trick. This produces a branch that is entirely disconnected from any other branch, and the first commit you'll make in this branch will have no parent, which will make it a root commit.
  2. Clean your index using git rm --cached * .gitignore.
  3. Take a deep breath and delete entire working tree using rm -fr * .gitignore. Internal .git directory will stay untouched, because the * wildcard doesn't match it.
  4. Copy in your VeryBigBinary.exe, or your VeryHeavyDirectory/.
  5. Add it && commit it.
  6. Now it becomes tricky -- if you push it into the remote as a branch all your developers will download it the next time they invoke git fetch clogging their connection. You can avoid this by pushing a tag instead of a branch. This can still impact your colleague's bandwidth and filesystem storage if they have a habit of typing git fetch <remote> --tags, but read on for a workaround. Go ahead and git tag 1.0.0bin
  7. Push your orphan tag git push <remote> 1.0.0bin.
  8. Just so you never push your binary branch by accident, you can delete it git branch -D binaryStuff. Your commit will not be marked for garbage collection, because an orphan tag pointing on it 1.0.0bin is enough to keep it alive.

Checking out the Binary File

  1. How do I (or my colleagues) get the VeryBigBinary.exe checked out into the current working tree? If your current working branch is for example master you can simply git checkout 1.0.0bin -- VeryBigBinary.exe.
  2. This will fail if you don't have the orphan tag 1.0.0bin downloaded, in which case you'll have to git fetch <remote> 1.0.0bin beforehand.
  3. You can add the VeryBigBinary.exe into your master's .gitignore, so that no-one on your team will pollute the main history of the project with the binary by accident.

Completely Deleting the Binary File

If you decide to completely purge VeryBigBinary.exe from your local repository, your remote repository and your colleague's repositories you can just:

  1. Delete the orphan tag on the remote git push <remote> :refs/tags/1.0.0bin
  2. Delete the orphan tag locally (deletes all other unreferenced tags) git tag -l | xargs git tag -d && git fetch --tags. Taken from SO 1841341 with slight modification.
  3. Use a git gc trick to delete your now unreferenced commit locally. git -c gc.reflogExpire=0 -c gc.reflogExpireUnreachable=0 -c gc.rerereresolved=0 -c gc.rerereunresolved=0 -c gc.pruneExpire=now gc "$@". It will also delete all other unreferenced commits. Taken from SO 1904860
  4. If possible, repeat the git gc trick on the remote. It is possible if you're self-hosting your repository and might not be possible with some git providers, like github or in some corporate environments. If you're hosting with a provider that doesn't give you ssh access to the remote just let it be. It is possible that your provider's infrastructure will clean your unreferenced commit in their own sweet time. If you're in a corporate environment you can advice your IT to run a cron job garbage collecting your remote once per week or so. Whether they do or don't will not have any impact on your team in terms of bandwidth and storage, as long as you advise your colleagues to always git clone -b master --single-branch <url> instead of git clone.
  5. All your colleagues who want to get rid of outdated orphan tags need only to apply steps 2-3.
  6. You can then repeat the steps 1-8 of Adding the Binary Files to create a new orphan tag 2.0.0bin. If you're worried about your colleagues typing git fetch <remote> --tags you can actually name it again 1.0.0bin. This will make sure that the next time they fetch all the tags the old 1.0.0bin will be unreferenced and marked for subsequent garbage collection (using step 3). When you try to overwrite a tag on the remote you have to use -f like this: git push -f <remote> <tagname>

Afterword

  • OTABS doesn't touch your master or any other source code/development branches. The commit hashes, all of the history, and small size of these branches is unaffected. If you've already bloated your source code history with binary files you'll have to clean it up as a separate piece of work. This script might be useful.

  • Confirmed to work on Windows with git-bash.

  • It is a good idea to apply a set of standard trics to make storage of binary files more efficient. Frequent running of git gc (without any additional arguments) makes git optimise underlying storage of your files by using binary deltas. However, if your files are unlikely to stay similar from commit to commit you can switch off binary deltas altogether. Additionally, because it makes no sense to compress already compressed or encrypted files, like .zip, .jpg or .crypt, git allows you to switch off compression of the underlying storage. Unfortunately it's an all-or-nothing setting affecting your source code as well.

  • You might want to script up parts of OTABS to allow for quicker usage. In particular, scripting steps 2-3 from Completely Deleting Binary Files into an update git hook could give a compelling but perhaps dangerous semantics to git fetch ("fetch and delete everything that is out of date").

  • You might want to skip the step 4 of Completely Deleting Binary Files to keep a full history of all binary changes on the remote at the cost of the central repository bloat. Local repositories will stay lean over time.

  • In Java world it is possible to combine this solution with maven --offline to create a reproducible offline build stored entirely in your version control (it's easier with maven than with gradle). In Golang world it is feasible to build on this solution to manage your GOPATH instead of go get. In python world it is possible to combine this with virtualenv to produce a self-contained development environment without relying on PyPi servers for every build from scratch.

  • If your binary files change very often, like build artifacts, it might be a good idea to script a solution which stores 5 most recent versions of the artifacts in the orphan tags monday_bin, tuesday_bin, ..., friday_bin, and also an orphan tag for each release 1.7.8bin 2.0.0bin, etc. You can rotate the weekday_bin and delete old binaries daily. This way you get the best of two worlds: you keep the entire history of your source code but only the relevant history of your binary dependencies. It is also very easy to get the binary files for a given tag without getting entire source code with all its history: git init && git remote add <name> <url> && git fetch <name> <tag> should do it for you.

Reset AutoIncrement in SQL Server after Delete

Issue the following command to reseed mytable to start at 1:

DBCC CHECKIDENT (mytable, RESEED, 0)

Read about it in the Books on Line (BOL, SQL help). Also be careful that you don't have records higher than the seed you are setting.

How to set default value for HTML select?

You could use...

<option <?= ($temp == $value) ? "SELECTED" : "" ?> >$value</opton>

Edit: I thought I was looking at PHP questions... Sorry.

Convert PEM to PPK file format

I'm rather shocked that this has not been answered since the solution is very simple.

As mentioned in previous posts, you would not want to convert it using C#, but just once. This is easy to do with PuTTYGen.

  1. Download your .pem from AWS
  2. Open PuTTYgen
  3. Click "Load" on the right side about 3/4 down
  4. Set the file type to *.*
  5. Browse to, and Open your .pem file
  6. PuTTY will auto-detect everything it needs, and you just need to click "Save private key" and you can save your ppk key for use with PuTTY

Enjoy!

java.net.URL read stream to byte[]

Just extending Barnards's answer with commons-io. Separate answer because I can not format code in comments.

InputStream is = null;
try {
  is = url.openStream ();
  byte[] imageBytes = IOUtils.toByteArray(is);
}
catch (IOException e) {
  System.err.printf ("Failed while reading bytes from %s: %s", url.toExternalForm(), e.getMessage());
  e.printStackTrace ();
  // Perform any other exception handling that's appropriate.
}
finally {
  if (is != null) { is.close(); }
}

http://commons.apache.org/io/api-1.4/org/apache/commons/io/IOUtils.html#toByteArray(java.io.InputStream)

Where is the syntax for TypeScript comments documented?

Future

The TypeScript team, and other TypeScript involved teams, plan to create a standard formal TSDoc specification. The 1.0.0 draft hasn't been finalised yet: https://github.com/Microsoft/tsdoc#where-are-we-on-the-roadmap

enter image description here

Current

TypeScript uses JSDoc. e.g.

/** This is a description of the foo function. */
function foo() {
}

To learn jsdoc : https://jsdoc.app/

Demo

But you don't need to use the type annotation extensions in JSDoc.

You can (and should) still use other jsdoc block tags like @returns etc.

Example

Just an example. Focus on the types (not the content).

JSDoc version (notice types in docs):

/**
 * Returns the sum of a and b
 * @param {number} a
 * @param {number} b
 * @returns {number}
 */
function sum(a, b) {
    return a + b;
}

TypeScript version (notice the re-location of types):

/**
 * Takes two numbers and returns their sum
 * @param a first input to sum
 * @param b second input to sum
 * @returns sum of a and b
 */
function sum(a: number, b: number): number {
    return a + b;
}

Hidden TextArea

<textarea name="hide" style="display:none;"></textarea>

This sets the css display property to none, which prevents the browser from rendering the textarea.

How to create an integer-for-loop in Ruby?

If you're doing this in your erb view (for Rails), be mindful of the <% and <%= differences. What you'd want is:

<% (1..x).each do |i| %>
  Code to display using <%= stuff %> that you want to display    
<% end %>

For plain Ruby, you can refer to: http://www.tutorialspoint.com/ruby/ruby_loops.htm

Add a new line to the end of a JtextArea

Instead of using JTextArea.setText(String text), use JTextArea.append(String text).

Appends the given text to the end of the document. Does nothing if the model is null or the string is null or empty.

This will add text on to the end of your JTextArea.

Another option would be to use getText() to get the text from the JTextArea, then manipulate the String (add or remove or change the String), then use setText(String text) to set the text of the JTextArea to be the new String.

sql like operator to get the numbers only

You can use the following to only include valid characters:

SQL

SELECT * FROM @Table
WHERE Col NOT LIKE '%[^0-9.]%'

Results

Col
---------
234.62
6435.23
2

What is the difference between UTF-8 and Unicode?

"Unicode" is unfortunately used in various different ways, depending on the context. Its most correct use (IMO) is as a coded character set - i.e. a set of characters and a mapping between the characters and integer code points representing them.

UTF-8 is a character encoding - a way of converting from sequences of bytes to sequences of characters and vice versa. It covers the whole of the Unicode character set. ASCII is encoded as a single byte per character, and other characters take more bytes depending on their exact code point (up to 4 bytes for all currently defined code points, i.e. up to U-0010FFFF, and indeed 4 bytes could cope with up to U-001FFFFF).

When "Unicode" is used as the name of a character encoding (e.g. as the .NET Encoding.Unicode property) it usually means UTF-16, which encodes most common characters as two bytes. Some platforms (notably .NET and Java) use UTF-16 as their "native" character encoding. This leads to hairy problems if you need to worry about characters which can't be encoded in a single UTF-16 value (they're encoded as "surrogate pairs") - but most developers never worry about this, IME.

Some references on Unicode:

Getting realtime output using subprocess

I ran into the same problem awhile back. My solution was to ditch iterating for the read method, which will return immediately even if your subprocess isn't finished executing, etc.

golang why don't we have a set datastructure

Partly, because Go doesn't have generics (so you would need one set-type for every type, or fall back on reflection, which is rather inefficient).

Partly, because if all you need is "add/remove individual elements to a set" and "relatively space-efficient", you can get a fair bit of that simply by using a map[yourtype]bool (and set the value to true for any element in the set) or, for more space efficiency, you can use an empty struct as the value and use _, present = the_setoid[key] to check for presence.

Getting a timestamp for today at midnight?

$midnight = strtotime('midnight'); is valid
You can also try out strtotime('12am') or strtotime('[input any time you wish to here. e.g noon, 6pm, 3pm, 8pm, etc]'). I skipped adding today before midnight because the default is today.

Add item to array in VBScript

Based on Charles Clayton's answer, but slightly simplified...

' add item to array
Sub ArrayAdd(arr, val)
    ReDim Preserve arr(UBound(arr) + 1)
    arr(UBound(arr)) = val
End Sub

Used like so

a = Array()
AddItem(a, 5)
AddItem(a, "foo")

How to set image on QPushButton?

I don't think you can set arbitrarily sized images on any of the existing button classes. If you want a simple image behaving like a button, you can write your own QAbstractButton-subclass, something like:

class ImageButton : public QAbstractButton {
Q_OBJECT
public:
...
    void setPixmap( const QPixmap& pm ) { m_pixmap = pm; update(); }
    QSize sizeHint() const { return m_pixmap.size(); }
protected:
    void paintEvent( QPaintEvent* e ) {
        QPainter p( this );
        p.drawPixmap( 0, 0, m_pixmap );
    }
};

Difference between VARCHAR2(10 CHAR) and NVARCHAR2(10)

The NVARCHAR2 datatype was introduced by Oracle for databases that want to use Unicode for some columns while keeping another character set for the rest of the database (which uses VARCHAR2). The NVARCHAR2 is a Unicode-only datatype.

One reason you may want to use NVARCHAR2 might be that your DB uses a non-Unicode character set and you still want to be able to store Unicode data for some columns without changing the primary character set. Another reason might be that you want to use two Unicode character set (AL32UTF8 for data that comes mostly from western Europe, AL16UTF16 for data that comes mostly from Asia for example) because different character sets won't store the same data equally efficiently.

Both columns in your example (Unicode VARCHAR2(10 CHAR) and NVARCHAR2(10)) would be able to store the same data, however the byte storage will be different. Some strings may be stored more efficiently in one or the other.

Note also that some features won't work with NVARCHAR2, see this SO question: