Programs & Examples On #Particle system

The term particle system refers to a computer graphics technique that uses a large number of very small sprites.

Run task only if host does not belong to a group

You can set a control variable in vars files located in group_vars/ or directly in hosts file like this:

[vagrant:vars]
test_var=true

[location-1]
192.168.33.10 hostname=apollo

[location-2]
192.168.33.20 hostname=zeus

[vagrant:children]
location-1
location-2

And run tasks like this:

- name: "test"
  command: "echo {{test_var}}"
  when: test_var is defined and test_var

How to vertically center a "div" element for all browsers using CSS?

Centering only vertically

If you don't care about Internet Explorer 6 and 7, you can use a technique that involves two containers.

The outer container:

  • should have display: table;

The inner container:

  • should have display: table-cell;
  • should have vertical-align: middle;

The content box:

  • should have display: inline-block;

You can add any content you want to the content box without caring about its width or height!

Demo:

_x000D_
_x000D_
body {
    margin: 0;
}

.outer-container {
    position: absolute;
    display: table;
    width: 100%; /* This could be ANY width */
    height: 100%; /* This could be ANY height */
    background: #ccc;
}

.inner-container {
    display: table-cell;
    vertical-align: middle;
}

.centered-content {
    display: inline-block;
    background: #fff;
    padding: 20px;
    border: 1px solid #000;
}
_x000D_
<div class="outer-container">
   <div class="inner-container">
     <div class="centered-content">
        Malcolm in the Middle
     </div>
   </div>
</div>
_x000D_
_x000D_
_x000D_

See also this Fiddle!


Centering horizontally and vertically

If you want to center both horizontally and vertically, you also need the following.

The inner container:

  • should have text-align: center;

The content box:

  • should re-adjust the horizontal text-alignment to for example text-align: left; or text-align: right;, unless you want text to be centered

Demo:

_x000D_
_x000D_
body {
    margin: 0;
}

.outer-container {
    position: absolute;
    display: table;
    width: 100%; /* This could be ANY width */
    height: 100%; /* This could be ANY height */
    background: #ccc;
}

.inner-container {
    display: table-cell;
    vertical-align: middle;
    text-align: center;
}

.centered-content {
    display: inline-block;
    text-align: left;
    background: #fff;
    padding: 20px;
    border: 1px solid #000;
}
_x000D_
<div class="outer-container">
   <div class="inner-container">
     <div class="centered-content">
         Malcolm in the Middle
     </div>
   </div>
</div>
_x000D_
_x000D_
_x000D_

See also this Fiddle!

How to kill all processes matching a name?

If you want to execute the output of a command, you can put it inside $(...), however for your specific task take a look at the killall and pkill commands.

Conditional step/stage in Jenkins pipeline

Doing the same in declarative pipeline syntax, below are few examples:

stage('master-branch-stuff') {
    when {
        branch 'master'
    }
    steps {
        echo 'run this stage - ony if the branch = master branch'
    }
}

stage('feature-branch-stuff') {
    when {
        branch 'feature/*'
    }
    steps {
        echo 'run this stage - only if the branch name started with feature/'
    }
}

stage('expression-branch') {
    when {
        expression {
            return env.BRANCH_NAME != 'master';
        }
    }
    steps {
        echo 'run this stage - when branch is not equal to master'
    }
}

stage('env-specific-stuff') {
    when { 
        environment name: 'NAME', value: 'this' 
    }
    steps {
        echo 'run this stage - only if the env name and value matches'
    }
}

More effective ways coming up - https://issues.jenkins-ci.org/browse/JENKINS-41187
Also look at - https://jenkins.io/doc/book/pipeline/syntax/#when


The directive beforeAgent true can be set to avoid spinning up an agent to run the conditional, if the conditional doesn't require git state to decide whether to run:

when { beforeAgent true; expression { return isStageConfigured(config) } }

Release post and docs


UPDATE
New WHEN Clause
REF: https://jenkins.io/blog/2018/04/09/whats-in-declarative

equals - Compares two values - strings, variables, numbers, booleans - and returns true if they’re equal. I’m honestly not sure how we missed adding this earlier! You can do "not equals" comparisons using the not { equals ... } combination too.

changeRequest - In its simplest form, this will return true if this Pipeline is building a change request, such as a GitHub pull request. You can also do more detailed checks against the change request, allowing you to ask "is this a change request against the master branch?" and much more.

buildingTag - A simple condition that just checks if the Pipeline is running against a tag in SCM, rather than a branch or a specific commit reference.

tag - A more detailed equivalent of buildingTag, allowing you to check against the tag name itself.

How do I parse JSON into an int?

The question is kind of old, but I get a good result creating a function to convert an object in a Json string from a string variable to an integer

function getInt(arr, prop) {
    var int;
    for (var i=0 ; i<arr.length ; i++) {
        int = parseInt(arr[i][prop])
            arr[i][prop] = int;
    }
    return arr;
  }

the function just go thru the array and return all elements of the object of your selection as an integer

The multi-part identifier could not be bound

Did you forget to join some tables? If not then you probably need to use some aliases.

How to destroy a JavaScript object?

You can't delete objects, they are removed when there are no more references to them. You can delete references with delete.

However, if you have created circular references in your objects you may have to de-couple some things.

jQuery.animate() with css class only, without explicit styles

The jQueryUI provides a extension to animate function that allows you to animate css class.

edit: Example here

There are also methods to add/remove/toggle class which you might also be interested in.

Forward host port to docker container

If MongoDB and RabbitMQ are running on the Host, then the port should already exposed as it is not within Docker.

You do not need the -p option in order to expose ports from container to host. By default, all port are exposed. The -p option allows you to expose a port from the container to the outside of the host.

So, my guess is that you do not need -p at all and it should be working fine :)

Can you hide the controls of a YouTube embed without enabling autoplay?

If you add this ?showinfo=0&iv_load_policy=3&controls=0 before the end of your src, it will take out everything but the bottom right YouTube logo
working example: http://jsfiddle.net/42gxdf0f/1/

MySQL Insert with While Loop

drop procedure if exists doWhile;
DELIMITER //  
CREATE PROCEDURE doWhile()   
BEGIN
DECLARE i INT DEFAULT 2376921001; 
WHILE (i <= 237692200) DO
    INSERT INTO `mytable` (code, active, total) values (i, 1, 1);
    SET i = i+1;
END WHILE;
END;
//  

CALL doWhile(); 

nuget 'packages' element is not declared warning

You can always make simple xsd schema for 'packages.config' to get rid of this warning. To do this, create file named "packages.xsd":

<?xml version="1.0" encoding="utf-8" ?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"
      targetNamespace="urn:packages" xmlns="urn:packages">
  <xs:element name="packages">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="package" maxOccurs="unbounded">
          <xs:complexType>
            <xs:attribute name="id" type="xs:string" use="required" />
            <xs:attribute name="version" type="xs:string" use="required" />
            <xs:attribute name="targetFramework" type="xs:string" use="optional" />
            <xs:attribute name="allowedVersions" type="xs:string" use="optional" />
          </xs:complexType>
        </xs:element>
      </xs:sequence>
    </xs:complexType>
  </xs:element>
</xs:schema>

Location of this file (two options)

  • In the same folder as 'packages.config' file,
  • If you want to share packages.xsd across multiple projects, move it to the Visual Studio Schemas folder (the path may slightly differ, it's D:\Program Files (x86)\Microsoft Visual Studio 10.0\Xml\Schemas for me).

Then, edit <packages> tag in packages.config file (add xmlns attribute):

<packages xmlns="urn:packages">

Now the warning should disappear (even if packages.config file is open in Visual Studio).

java.util.zip.ZipException: error in opening zip file

I've seen this exception before when whatever the JVM considers to be a temp directory is not accessible due to not being there or not having permission to write.

Deleting records before a certain date

DELETE FROM table WHERE date < '2011-09-21 08:21:22';

Highest Salary in each department

Not sure why no one has mentioned the Group By .... Having syntax. It specifically addresses these requirements.

select EmpName,DeptId,Salary from EmpDetails group by DeptId having Salary=max(Salary);

Bootstrap push div content to new line

If your your list is dynamically generated with unknown number and your target is to always have last div in a new line set last div class to "col-xl-12" and remove other classes so it will always take a full row.

This is a copy of your code corrected so that last div always occupy a full row (I although removed unnecessary classes).

_x000D_
_x000D_
<link href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet">_x000D_
<div class="grid">_x000D_
  <div class="row">_x000D_
    <div class="col-sm-3">Under me should be a DIV</div>_x000D_
    <div class="col-md-6 col-sm-5">Under me should be a DIV</div>_x000D_
    <div class="col-xl-12">I am the last DIV and I always take a full row for my self!!</div>_x000D_
  </div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

About catching ANY exception

There are multiple ways to do this in particular with Python 3.0 and above

Approach 1

This is simple approach but not recommended because you would not know exactly which line of code is actually throwing the exception:

def bad_method():
    try:
        sqrt = 0**-1
    except Exception as e:
        print(e)

bad_method()

Approach 2

This approach is recommended because it provides more detail about each exception. It includes:

  • Line number for your code
  • File name
  • The actual error in more verbose way

The only drawback is tracback needs to be imported.

import traceback

def bad_method():
    try:
        sqrt = 0**-1
    except Exception:
        print(traceback.print_exc())

bad_method()

mappedBy reference an unknown target entity property

I know the answer by @Pascal Thivent has solved the issue. I would like to add a bit more to his answer to others who might be surfing this thread.

If you are like me in the initial days of learning and wrapping your head around the concept of using the @OneToMany annotation with the 'mappedBy' property, it also means that the other side holding the @ManyToOne annotation with the @JoinColumn is the 'owner' of this bi-directional relationship.

Also, mappedBy takes in the instance name (mCustomer in this example) of the Class variable as an input and not the Class-Type (ex:Customer) or the entity name(Ex:customer).

BONUS : Also, look into the orphanRemoval property of @OneToMany annotation. If it is set to true, then if a parent is deleted in a bi-directional relationship, Hibernate automatically deletes it's children.

How can I send the "&" (ampersand) character via AJAX?

encodeURIComponent(Your text here);

This will truncate special characters.

Access-Control-Allow-Origin wildcard subdomains, ports and protocols

Based on DaveRandom's answer, I was also playing around and found a slightly simpler Apache solution that produces the same result (Access-Control-Allow-Origin is set to the current specific protocol + domain + port dynamically) without using any rewrite rules:

SetEnvIf Origin ^(https?://.+\.mywebsite\.com(?::\d{1,5})?)$   CORS_ALLOW_ORIGIN=$1
Header append Access-Control-Allow-Origin  %{CORS_ALLOW_ORIGIN}e   env=CORS_ALLOW_ORIGIN
Header merge  Vary "Origin"

And that's it.

Those who want to enable CORS on the parent domain (e.g. mywebsite.com) in addition to all its subdomains can simply replace the regular expression in the first line with this one:

^(https?://(?:.+\.)?mywebsite\.com(?::\d{1,5})?)$.

Note: For spec compliance and correct caching behavior, ALWAYS add the Vary: Origin response header for CORS-enabled resources, even for non-CORS requests and those from a disallowed origin (see example why).

Python JSON serialize a Decimal object

For anybody that wants a quick solution here is how I removed Decimal from my queries in Django

total_development_cost_var = process_assumption_objects.values('total_development_cost').aggregate(sum_dev = Sum('total_development_cost', output_field=FloatField()))
total_development_cost_var = list(total_development_cost_var.values())
  • Step 1: use , output_field=FloatField() in you r query
  • Step 2: use list eg list(total_development_cost_var.values())

Hope it helps

make: *** No rule to make target `all'. Stop

Your makefile should ideally be named makefile, not make. Note that you can call your makefile anything you like, but as you found, you then need the -f option with make to specify the name of the makefile. Using the default name of makefile just makes life easier.

How to change the date format from MM/DD/YYYY to YYYY-MM-DD in PL/SQL?

This worked for me! You can convert to datatype you want be it a date or string

to_char(TO_DATE(TO_CHAR(end_date),'MM-DD-YYYY'),'YYYY-MM-DD') AS end_date

draw diagonal lines in div background with CSS

Please check the following.

<canvas id="myCanvas" width="200" height="100"></canvas>
<div id="mydiv"></div>

JS:

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.strokeStyle="red";
ctx.moveTo(0,100);
ctx.lineTo(200,0);
ctx.stroke();
ctx.moveTo(0,0);
ctx.lineTo(200,100);
ctx.stroke();

CSS:

html, body { 
  margin: 0;
  padding: 0;
}

#myCanvas {
  padding: 0;
  margin: 0;
  width: 200px;
  height: 100px;
}

#mydiv {
  position: absolute;
  left: 0px;
  right: 0;
  height: 102px;
  width: 202px;
  background: rgba(255,255,255,0);
  padding: 0;
  margin: 0;
}

jsfiddle

How do I convert from a money datatype in SQL server?

You can try like this:

SELECT PARSENAME('$'+ Convert(varchar,Convert(money,@MoneyValue),1),2)

get string value from HashMap depending on key name

You can use the get(Object key) method from the HashMap. Be aware that i many cases your Key Class should override the equals method, to be a useful class for a Map key.

How do I assign ls to an array in Linux Bash?

Whenever possible, you should avoid parsing the output of ls (see Greg's wiki on the subject). Basically, the output of ls will be ambiguous if there are funny characters in any of the filenames. It's also usually a waste of time. In this case, when you execute ls -d */, what happens is that the shell expands */ to a list of subdirectories (which is already exactly what you want), passes that list as arguments to ls -d, which looks at each one, says "yep, that's a directory all right" and prints it (in an inconsistent and sometimes ambiguous format). The ls command isn't doing anything useful!

Well, ok, it is doing one thing that's useful: if there are no subdirectories, */ will get left as is, ls will look for a subdirectory named "*", not find it, print an error message that it doesn't exist (to stderr), and not print the "*/" (to stdout).

The cleaner way to make an array of subdirectory names is to use the glob (*/) without passing it to ls. But in order to avoid putting "*/" in the array if there are no actual subdirectories, you should set nullglob first (again, see Greg's wiki):

shopt -s nullglob
array=(*/)
shopt -u nullglob # Turn off nullglob to make sure it doesn't interfere with anything later
echo "${array[@]}"  # Note double-quotes to avoid extra parsing of funny characters in filenames

If you want to print an error message if there are no subdirectories, you're better off doing it yourself:

if (( ${#array[@]} == 0 )); then
    echo "No subdirectories found" >&2
fi

Matching a space in regex

I'm trying out [[:space:]] in an instance where it looks like bloggers in WordPress are using non-standard space characters. It looks like it will work.

How to throw RuntimeException ("cannot find symbol")

Just for others: be sure it is new RuntimeException, not new RuntimeErrorException which needs error as an argument.

How to connect to Mysql Server inside VirtualBox Vagrant?

For anyone trying to do this using mysql workbench or sequel pro these are the inputs:

Mysql Host: 192.168.56.101 (or ip that you choose for it)
username: root (or mysql username u created)
password: **** (your mysql password)
database: optional
port: optional (unless you chose another port, defaults to 3306)

ssh host: 192.168.56.101 (or ip that you choose for this vm, like above)
ssh user: vagrant (vagrants default username)
ssh password: vagrant (vagrants default password)
ssh port: optional (unless you chose another)

source: https://coderwall.com/p/yzwqvg

How can I stream webcam video with C#?

If you want to record video from within a web browser, I think your only option is Flash. We are looking to do the same thing. We are also primarily a .NET house and I don't see a way to use .NET to capture the webcam _from_within_the_browser_. All of the other solutions mentioned here would probably work great if you are happy to settle for a desktop app

Angular 5 Reactive Forms - Radio Button Group

I tried your code, you didn't assign/bind a value to your formControlName.

In HTML file:

<form [formGroup]="form">
   <label>
     <input type="radio" value="Male" formControlName="gender">
       <span>male</span>
   </label>
   <label>
     <input type="radio" value="Female" formControlName="gender">
       <span>female</span>
   </label>
</form>

In the TS file:

  form: FormGroup;
  constructor(fb: FormBuilder) {
    this.name = 'Angular2'
    this.form = fb.group({
      gender: ['', Validators.required]
    });
  }

Make sure you use Reactive form properly: [formGroup]="form" and you don't need the name attribute.

In my sample. words male and female in span tags are the values display along the radio button and Male and Female values are bind to formControlName

See the screenshot: enter image description here

To make it shorter:

<form [formGroup]="form">
  <input type="radio" value='Male' formControlName="gender" >Male
  <input type="radio" value='Female' formControlName="gender">Female
</form>

enter image description here

Hope it helps:)

Python: Best way to add to sys.path relative to the current running script

I'm using:

import sys,os
sys.path.append(os.getcwd())

Excel Create Collapsible Indented Row Hierarchies

Create a Pivot Table. It has these features and many more.

If you are dead-set on doing this yourself then you could add shapes to the worksheet and use VBA to hide and unhide rows and columns on clicking the shapes.

How to make child process die after parent exits?

Inspired by another answer here, I came up with the following all-POSIX solution. The general idea is to create an intermediate process between the parent and the child, that has one purpose: Notice when the parent dies, and explicitly kill the child.

This type of solution is useful when the code in the child can't be modified.

int p[2];
pipe(p);
pid_t child = fork();
if (child == 0) {
    close(p[1]); // close write end of pipe
    setpgid(0, 0); // prevent ^C in parent from stopping this process
    child = fork();
    if (child == 0) {
        close(p[0]); // close read end of pipe (don't need it here)
        exec(...child process here...);
        exit(1);
    }
    read(p[0], 1); // returns when parent exits for any reason
    kill(child, 9);
    exit(1);
}

There are two small caveats with this method:

  • If you deliberately kill the intermediate process, then the child won't be killed when the parent dies.
  • If the child exits before the parent, then the intermediate process will try to kill the original child pid, which could now refer to a different process. (This could be fixed with more code in the intermediate process.)

As an aside, the actual code I'm using is in Python. Here it is for completeness:

def run(*args):
    (r, w) = os.pipe()
    child = os.fork()
    if child == 0:
        os.close(w)
        os.setpgid(0, 0)
        child = os.fork()
        if child == 0:
            os.close(r)
            os.execl(args[0], *args)
            os._exit(1)
        os.read(r, 1)
        os.kill(child, 9)
        os._exit(1)
    os.close(r)

What is a "web service" in plain English?

In over simplified terms a web service is something that provides data as a service over the http protocol. Granted that isn't alway the case....but it is close.

Standard Web Services use The SOAP protocol which defines the communication and structure of messages, and XML is the data format.

Web services are designed to allow applications built using different technologies to communicate with each other without issues.

Examples of web services are things like Weather.com providing weather information for that you can use on your site, or UPS providing a method to request shipping quotes or tracking of packages.

Edit

Changed wording in reference to SOAP, as it is not always SOAP as I mentioned, but wanted to make it more clear. The key is providing data as a service, not a UI element.

Hibernate, @SequenceGenerator and allocationSize

Steve Ebersole & other members,
Would you kindly explain the reason for an id with a larger gap(by default 50)? I am using Hibernate 4.2.15 and found the following code in org.hibernate.id.enhanced.OptimizerFactory cass.

if ( lo > maxLo ) {
   lastSourceValue = callback.getNextValue();
   lo = lastSourceValue.eq( 0 ) ? 1 : 0;
   hi = lastSourceValue.copy().multiplyBy( maxLo+1 ); 
}  
value = hi.copy().add( lo++ );

Whenever it hits the inside of the if statement, hi value is getting much larger. So, my id during the testing with the frequent server restart generates the following sequence ids:
1, 2, 3, 4, 19, 250, 251, 252, 400, 550, 750, 751, 752, 850, 1100, 1150.

I know you already said it didn't conflict with the spec, but I believe this will be very unexpected situation for most developers.

Anyone's input will be much helpful.

Jihwan

UPDATE: ne1410s: Thanks for the edit.
cfrick: OK. I will do that. It was my first post here and wasn't sure how to use it.

Now, I understood better why maxLo was used for two purposes: Since the hibernate calls the DB sequence once, keep increase the id in Java level, and saves it to the DB, the Java level id value should consider how much was changed without calling the DB sequence when it calls the sequence next time.

For example, sequence id was 1 at a point and hibernate entered 5, 6, 7, 8, 9 (with allocationSize = 5). Next time, when we get the next sequence number, DB returns 2, but hibernate needs to use 10, 11, 12... So, that is why "hi = lastSourceValue.copy().multiplyBy( maxLo+1 )" is used to get a next id 10 from the 2 returned from the DB sequence. It seems only bothering thing was during the frequent server restart and this was my issue with the larger gap.

So, when we use the SEQUENCE ID, the inserted id in the table will not match with the SEQUENCE number in DB.

Facebook share link - can you customize the message body text?

Facebook does not allow you to change the "What's on your mind?" text box, unless of course you're developing an application for use on Facebook.

Laravel 4: how to run a raw SQL?

Laravel raw sql – Insert query:

lets create a get link to insert data which is accessible through url . so our link name is ‘insertintodb’ and inside that function we use db class . db class helps us to interact with database . we us db class static function insert . Inside insert function we will write our PDO query to insert data in database . in below query we will insert ‘ my title ‘ and ‘my content’ as data in posts table .

put below code in your web.php file inside routes directory :

Route::get('/insertintodb',function(){
DB::insert('insert into posts(title,content) values (?,?)',['my title','my content']);
});

Now fire above insert query from browser link below :

localhost/yourprojectname/insertintodb

You can see output of above insert query by going into your database table .you will find a record with id 1 .

Laravel raw sql – Read query :

Now , lets create a get link to read data , which is accessible through url . so our link name is ‘readfromdb’. we us db class static function read . Inside read function we will write our PDO query to read data from database . in below query we will read data of id ‘1’ from posts table .

put below code in your web.php file inside routes directory :

Route::get('/readfromdb',function() {
    $result =  DB::select('select * from posts where id = ?', [1]);
    var_dump($result);
});

now fire above read query from browser link below :

localhost/yourprojectname/readfromdb

How can I get the current user directory?

Try:

System.IO.Directory.GetParent(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)).FullName/

Swift: Sort array of objects alphabetically

let sortArray =  array.sorted(by: { $0.name.lowercased() < $1.name.lowercased() })

"The import org.springframework cannot be resolved."

Add these dependencies

</dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>4.3.7.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.3.7.RELEASE</version>
    </dependency>
</dependencies>

Remove a HTML tag but keep the innerHtml

Behold, for the simplest answer is mind blowing:

outerHTML is supported down to Internet Explorer 4 !

Here is to do it with javascript even without jQuery

element.outerHTML = element.innerHTML

with jQuery element = $('b')[0]; or without jQuery element = document.querySelector('b');

If you want it as a function:

function unwrap(selector) {
    var nodelist = document.querySelectorAll(selector);
    Array.prototype.forEach.call(nodelist, function(item,i){
        item.outerHTML = item.innerHTML; // or item.innerText if you want to remove all inner html tags 
    })
}

unwrap('b')

This should work in all major browser including old IE. in recent browser, we can even call forEach right on the nodelist.

function unwrap(selector) {
    document.querySelectorAll('b').forEach( (item,i) => {
        item.outerHTML = item.innerText;
    } )
}

Initial bytes incorrect after Java AES/CBC decryption

The IV that your using for decryption is incorrect. Replace this code

//Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(aesKey.getEncoded());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);

With this code

//Decrypt cipher
Cipher decryptCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
IvParameterSpec ivParameterSpec = new IvParameterSpec(encryptCipher.getIV());
decryptCipher.init(Cipher.DECRYPT_MODE, aesKey, ivParameterSpec);

And that should solve your problem.


Below includes an example of a simple AES class in Java. I do not recommend using this class in production environments, as it may not account for all of the specific needs of your application.

import java.nio.charset.StandardCharsets;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class AES 
{
    public static byte[] encrypt(final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
    {       
        return AES.transform(Cipher.ENCRYPT_MODE, keyBytes, ivBytes, messageBytes);
    }

    public static byte[] decrypt(final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
    {       
        return AES.transform(Cipher.DECRYPT_MODE, keyBytes, ivBytes, messageBytes);
    }

    private static byte[] transform(final int mode, final byte[] keyBytes, final byte[] ivBytes, final byte[] messageBytes) throws InvalidKeyException, InvalidAlgorithmParameterException
    {
        final SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");
        final IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
        byte[] transformedBytes = null;

        try
        {
            final Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");

            cipher.init(mode, keySpec, ivSpec);

            transformedBytes = cipher.doFinal(messageBytes);
        }        
        catch (NoSuchAlgorithmException | NoSuchPaddingException | IllegalBlockSizeException | BadPaddingException e) 
        {
            e.printStackTrace();
        }
        return transformedBytes;
    }

    public static void main(final String[] args) throws InvalidKeyException, InvalidAlgorithmParameterException
    {
        //Retrieved from a protected local file.
        //Do not hard-code and do not version control.
        final String base64Key = "ABEiM0RVZneImaq7zN3u/w==";

        //Retrieved from a protected database.
        //Do not hard-code and do not version control.
        final String shadowEntry = "AAECAwQFBgcICQoLDA0ODw==:ZtrkahwcMzTu7e/WuJ3AZmF09DE=";

        //Extract the iv and the ciphertext from the shadow entry.
        final String[] shadowData = shadowEntry.split(":");        
        final String base64Iv = shadowData[0];
        final String base64Ciphertext = shadowData[1];

        //Convert to raw bytes.
        final byte[] keyBytes = Base64.getDecoder().decode(base64Key);
        final byte[] ivBytes = Base64.getDecoder().decode(base64Iv);
        final byte[] encryptedBytes = Base64.getDecoder().decode(base64Ciphertext);

        //Decrypt data and do something with it.
        final byte[] decryptedBytes = AES.decrypt(keyBytes, ivBytes, encryptedBytes);

        //Use non-blocking SecureRandom implementation for the new IV.
        final SecureRandom secureRandom = new SecureRandom();

        //Generate a new IV.
        secureRandom.nextBytes(ivBytes);

        //At this point instead of printing to the screen, 
        //one should replace the old shadow entry with the new one.
        System.out.println("Old Shadow Entry      = " + shadowEntry);
        System.out.println("Decrytped Shadow Data = " + new String(decryptedBytes, StandardCharsets.UTF_8));
        System.out.println("New Shadow Entry      = " + Base64.getEncoder().encodeToString(ivBytes) + ":" + Base64.getEncoder().encodeToString(AES.encrypt(keyBytes, ivBytes, decryptedBytes)));
    }
}

Note that AES has nothing to do with encoding, which is why I chose to handle it separately and without the need of any third party libraries.

Drop all data in a pandas dataframe

My favorite:

df = df.iloc[0:0]

But be aware df.index.max() will be nan. To add items I use:

df.loc[0 if math.isnan(df.index.max()) else df.index.max() + 1] = data

How to check if input date is equal to today's date?

Try using moment.js

moment('dd/mm/yyyy').isSame(Date.now(), 'day');

You can replace 'day' string with 'year, month, minute' if you want.

AngularJS check if form is valid in controller

The BusinessCtrl is initialised before the createBusinessForm's FormController. Even if you have the ngController on the form won't work the way you wanted. You can't help this (you can create your ngControllerDirective, and try to trick the priority.) this is how angularjs works.

See this plnkr for example: http://plnkr.co/edit/WYyu3raWQHkJ7XQzpDtY?p=preview

How and when to use SLEEP() correctly in MySQL?

If you don't want to SELECT SLEEP(1);, you can also DO SLEEP(1); It's useful for those situations in procedures where you don't want to see output.

e.g.

SELECT ...
DO SLEEP(5);
SELECT ...

add a string prefix to each value in a string column using Pandas

Another solution with .loc:

df = pd.DataFrame({'col': ['a', 0]})
df.loc[df.index, 'col'] = 'string' + df['col'].astype(str)

This is not as quick as solutions above (>1ms per loop slower) but may be useful in case you need conditional change, like:

mask = (df['col'] == 0)
df.loc[mask, 'col'] = 'string' + df['col'].astype(str)

How to use jquery or ajax to update razor partial view in c#/asp.net for a MVC project

You can also use Url.Action for the path instead like so:

$.ajax({
        url: "@Url.Action("Holiday", "Calendar", new { area = "", year= (val * 1) + 1 })",                
        type: "GET",           
        success: function (partialViewResult) {            
            $("#refTable").html(partialViewResult);
        }
    });

How can I add JAR files to the web-inf/lib folder in Eclipse?

In case this helps anyone, if you are using a Git repo, make sure the jars make it into the WEB-INF/lib INSIDE the git repo and not just in the project WEB-INF/lib

Javascript event handler with parameters

let obj = MyObject();

elem.someEvent( function(){ obj.func(param) } );

//calls the MyObject.func, passing the param.

PHP output showing little black diamonds with a question mark

That can be caused by unicode or other charset mismatch. Try changing charset in your browser, in of the settings the text will look OK. Then it's question of how to convert your database contents to charset you use for displaying. (Which can actually be just adding utf-8 charset statement to your output.)

How to check whether a Storage item is set?

Best and Safest way i can suggest is this,

if(Object.prototype.hasOwnProperty.call(localStorage, 'infiniteScrollEnabled')){
    // init variable/set default variable for item
    localStorage.setItem("infiniteScrollEnabled", true);
}

This passes through ESLint's no-prototype-builtins rule.

Jquery insert new row into table at a certain index

Note:

$('#my_table > tbody:last').append(newRow); // this will add new row inside tbody

$("table#myTable tr").last().after(newRow);  // this will add new row outside tbody 
                                             //i.e. between thead and tbody
                                             //.before() will also work similar

Is HTML considered a programming language?

No - there's a big prejudice in IT against web design; but in this case the "real" programmers are on pretty firm ground.

If you've done a lot of web design work you've probably done some JavaScript, so you can put that down under 'programming languages'; if you want to list HTML as well, then I agree with the answer that suggests "Technologies".

But unless you're targeting agents who're trying to tick boxes rather than find you a good job, a bare list of things you've used doesn't really look all that good. You're better off listing the projects you've worked on and detailing the technologies you used on each; that demonstrates that you've got real experience of using them rather than just that you know some buzzwords.

HTML+CSS: How to force div contents to stay in one line?

div {
    display: flex;
    flex-direction: row; 
}

was the solution that worked for me. In some cases with div-lists this is needed.

some alternative direction values are row-reverse, column, column-reverse, unset, initial, inherit which do the things you expect them to do

Import local function from a module housed in another directory with relative imports in Jupyter Notebook using Python 3

All other answers here depends on adding code the the notebook(!)

In my opinion is bad practice to hardcode a specific path into the notebook code, or otherwise depend on the location, since this makes it really hard to refactor you code later on. Instead I would recommend you to add the root project folder to PYTHONPATH when starting up your Jupyter notebook server, either directly from the project folder like so

env PYTHONPATH=`pwd` jupyter notebook

or if you are starting it up from somewhere else, use the absolute path like so

env PYTHONPATH=/Users/foo/bar/project/ jupyter notebook

A better way to check if a path exists or not in PowerShell

To check if a Path exists to a directory, use this one:

$pathToDirectory = "c:\program files\blahblah\"
if (![System.IO.Directory]::Exists($pathToDirectory))
{
 mkdir $path1
}

To check if a Path to a file exists use what @Mathias suggested:

[System.IO.File]::Exists($pathToAFile)

Shell script to get the process ID on Linux

option -v is very important. It can exclude a grep expression itself

e.g.

ps -w | grep sshd | grep -v grep | awk '{print $1}' to get sshd id

Using the "animated circle" in an ImageView while loading stuff

You can do this by using the following xml

<RelativeLayout
    style="@style/GenericProgressBackground"
    android:id="@+id/loadingPanel"
    >
    <ProgressBar
        style="@style/GenericProgressIndicator"/>
</RelativeLayout>

With this style

<style name="GenericProgressBackground" parent="android:Theme">
    <item name="android:layout_width">fill_parent</item>    
    <item name="android:layout_height">fill_parent</item>
    <item name="android:background">#DD111111</item>    
    <item name="android:gravity">center</item>  
</style>
<style name="GenericProgressIndicator" parent="@android:style/Widget.ProgressBar.Small">
    <item name="android:layout_width">wrap_content</item>
    <item name="android:layout_height">wrap_content</item>
    <item name="android:indeterminate">true</item> 
</style>

To use this, you must hide your UI elements by setting the visibility value to GONE and whenever the data is loaded, call setVisibility(View.VISIBLE) on all your views to restore them. Don't forget to call findViewById(R.id.loadingPanel).setVisiblity(View.GONE) to hide the loading animation.

If you dont have a loading event/function but just want the loading panel to disappear after x seconds use a Handle to trigger the hiding/showing.

How do I make an Android EditView 'Done' button and hide the keyboard when clicked?

I have to point that out as a lot of people can struggle into that without knowing the problem.

If you want the kb to hide when clicking Done, and you set android:imeOptions="actionDone" & android:maxLines="1" without setting your EditText inputType it will NOT work as the default inputType for the EditText is not "text" as a lot of people think.

so, setting only inputType will give you the results you desire whatever what you are setting it to like "text", "number", ...etc.

how do you view macro code in access?

Open the Access Database, you will see Table, Query, Report, Module & Macro.
This contains the macros which can be used to invoke common MS-Access actions in a sequence.

For custom VBA macro, press ALT+F11.

'App not Installed' Error on Android

I had the same problem and here is how solved it : Go to the Manifest file and make sure you have the "Debuggable" and the "Test Only" attributes set to false. It worked for me :)

How to draw a standard normal distribution in R

Something like this perhaps?

x<-rnorm(100000,mean=10, sd=2)
hist(x,breaks=150,xlim=c(0,20),freq=FALSE)
abline(v=10, lwd=5)
abline(v=c(4,6,8,12,14,16), lwd=3,lty=3)

How to round double to nearest whole number and then convert to a float?

For what is worth:

the closest integer to any given input as shown in the following table can be calculated using Math.ceil or Math.floor depending of the distance between the input and the next integer

+-------+--------+
| input | output |
+-------+--------+
|     1 |      0 |
|     2 |      0 |
|     3 |      5 |
|     4 |      5 |
|     5 |      5 |
|     6 |      5 |
|     7 |      5 |
|     8 |     10 |
|     9 |     10 |
+-------+--------+

private int roundClosest(final int i, final int k) {
    int deic = (i % k);
    if (deic <= (k / 2.0)) {
        return (int) (Math.floor(i / (double) k) * k);
    } else {
        return (int) (Math.ceil(i / (double) k) * k);
    }
}

What's the difference between eval, exec, and compile?

The short answer, or TL;DR

Basically, eval is used to evaluate a single dynamically generated Python expression, and exec is used to execute dynamically generated Python code only for its side effects.

eval and exec have these two differences:

  1. eval accepts only a single expression, exec can take a code block that has Python statements: loops, try: except:, class and function/method definitions and so on.

    An expression in Python is whatever you can have as the value in a variable assignment:

    a_variable = (anything you can put within these parentheses is an expression)
    
  2. eval returns the value of the given expression, whereas exec ignores the return value from its code, and always returns None (in Python 2 it is a statement and cannot be used as an expression, so it really does not return anything).

In versions 1.0 - 2.7, exec was a statement, because CPython needed to produce a different kind of code object for functions that used exec for its side effects inside the function.

In Python 3, exec is a function; its use has no effect on the compiled bytecode of the function where it is used.


Thus basically:

>>> a = 5
>>> eval('37 + a')   # it is an expression
42
>>> exec('37 + a')   # it is an expression statement; value is ignored (None is returned)
>>> exec('a = 47')   # modify a global variable as a side effect
>>> a
47
>>> eval('a = 47')  # you cannot evaluate a statement
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    a = 47
      ^
SyntaxError: invalid syntax

The compile in 'exec' mode compiles any number of statements into a bytecode that implicitly always returns None, whereas in 'eval' mode it compiles a single expression into bytecode that returns the value of that expression.

>>> eval(compile('42', '<string>', 'exec'))  # code returns None
>>> eval(compile('42', '<string>', 'eval'))  # code returns 42
42
>>> exec(compile('42', '<string>', 'eval'))  # code returns 42,
>>>                                          # but ignored by exec

In the 'eval' mode (and thus with the eval function if a string is passed in), the compile raises an exception if the source code contains statements or anything else beyond a single expression:

>>> compile('for i in range(3): print(i)', '<string>', 'eval')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    for i in range(3): print(i)
      ^
SyntaxError: invalid syntax

Actually the statement "eval accepts only a single expression" applies only when a string (which contains Python source code) is passed to eval. Then it is internally compiled to bytecode using compile(source, '<string>', 'eval') This is where the difference really comes from.

If a code object (which contains Python bytecode) is passed to exec or eval, they behave identically, excepting for the fact that exec ignores the return value, still returning None always. So it is possible use eval to execute something that has statements, if you just compiled it into bytecode before instead of passing it as a string:

>>> eval(compile('if 1: print("Hello")', '<string>', 'exec'))
Hello
>>>

works without problems, even though the compiled code contains statements. It still returns None, because that is the return value of the code object returned from compile.

In the 'eval' mode (and thus with the eval function if a string is passed in), the compile raises an exception if the source code contains statements or anything else beyond a single expression:

>>> compile('for i in range(3): print(i)', '<string>'. 'eval')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    for i in range(3): print(i)
      ^
SyntaxError: invalid syntax

The longer answer, a.k.a the gory details

exec and eval

The exec function (which was a statement in Python 2) is used for executing a dynamically created statement or program:

>>> program = '''
for i in range(3):
    print("Python is cool")
'''
>>> exec(program)
Python is cool
Python is cool
Python is cool
>>> 

The eval function does the same for a single expression, and returns the value of the expression:

>>> a = 2
>>> my_calculation = '42 * a'
>>> result = eval(my_calculation)
>>> result
84

exec and eval both accept the program/expression to be run either as a str, unicode or bytes object containing source code, or as a code object which contains Python bytecode.

If a str/unicode/bytes containing source code was passed to exec, it behaves equivalently to:

exec(compile(source, '<string>', 'exec'))

and eval similarly behaves equivalent to:

eval(compile(source, '<string>', 'eval'))

Since all expressions can be used as statements in Python (these are called the Expr nodes in the Python abstract grammar; the opposite is not true), you can always use exec if you do not need the return value. That is to say, you can use either eval('my_func(42)') or exec('my_func(42)'), the difference being that eval returns the value returned by my_func, and exec discards it:

>>> def my_func(arg):
...     print("Called with %d" % arg)
...     return arg * 2
... 
>>> exec('my_func(42)')
Called with 42
>>> eval('my_func(42)')
Called with 42
84
>>> 

Of the 2, only exec accepts source code that contains statements, like def, for, while, import, or class, the assignment statement (a.k.a a = 42), or entire programs:

>>> exec('for i in range(3): print(i)')
0
1
2
>>> eval('for i in range(3): print(i)')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    for i in range(3): print(i)
      ^
SyntaxError: invalid syntax

Both exec and eval accept 2 additional positional arguments - globals and locals - which are the global and local variable scopes that the code sees. These default to the globals() and locals() within the scope that called exec or eval, but any dictionary can be used for globals and any mapping for locals (including dict of course). These can be used not only to restrict/modify the variables that the code sees, but are often also used for capturing the variables that the executed code creates:

>>> g = dict()
>>> l = dict()
>>> exec('global a; a, b = 123, 42', g, l)
>>> g['a']
123
>>> l
{'b': 42}

(If you display the value of the entire g, it would be much longer, because exec and eval add the built-ins module as __builtins__ to the globals automatically if it is missing).

In Python 2, the official syntax for the exec statement is actually exec code in globals, locals, as in

>>> exec 'global a; a, b = 123, 42' in g, l

However the alternate syntax exec(code, globals, locals) has always been accepted too (see below).

compile

The compile(source, filename, mode, flags=0, dont_inherit=False, optimize=-1) built-in can be used to speed up repeated invocations of the same code with exec or eval by compiling the source into a code object beforehand. The mode parameter controls the kind of code fragment the compile function accepts and the kind of bytecode it produces. The choices are 'eval', 'exec' and 'single':

  • 'eval' mode expects a single expression, and will produce bytecode that when run will return the value of that expression:

    >>> dis.dis(compile('a + b', '<string>', 'eval'))
      1           0 LOAD_NAME                0 (a)
                  3 LOAD_NAME                1 (b)
                  6 BINARY_ADD
                  7 RETURN_VALUE
    
  • 'exec' accepts any kinds of python constructs from single expressions to whole modules of code, and executes them as if they were module top-level statements. The code object returns None:

    >>> dis.dis(compile('a + b', '<string>', 'exec'))
      1           0 LOAD_NAME                0 (a)
                  3 LOAD_NAME                1 (b)
                  6 BINARY_ADD
                  7 POP_TOP                             <- discard result
                  8 LOAD_CONST               0 (None)   <- load None on stack
                 11 RETURN_VALUE                        <- return top of stack
    
  • 'single' is a limited form of 'exec' which accepts a source code containing a single statement (or multiple statements separated by ;) if the last statement is an expression statement, the resulting bytecode also prints the repr of the value of that expression to the standard output(!).

    An if-elif-else chain, a loop with else, and try with its except, else and finally blocks is considered a single statement.

    A source fragment containing 2 top-level statements is an error for the 'single', except in Python 2 there is a bug that sometimes allows multiple toplevel statements in the code; only the first is compiled; the rest are ignored:

    In Python 2.7.8:

    >>> exec(compile('a = 5\na = 6', '<string>', 'single'))
    >>> a
    5
    

    And in Python 3.4.2:

    >>> exec(compile('a = 5\na = 6', '<string>', 'single'))
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "<string>", line 1
        a = 5
            ^
    SyntaxError: multiple statements found while compiling a single statement
    

    This is very useful for making interactive Python shells. However, the value of the expression is not returned, even if you eval the resulting code.

Thus greatest distinction of exec and eval actually comes from the compile function and its modes.


In addition to compiling source code to bytecode, compile supports compiling abstract syntax trees (parse trees of Python code) into code objects; and source code into abstract syntax trees (the ast.parse is written in Python and just calls compile(source, filename, mode, PyCF_ONLY_AST)); these are used for example for modifying source code on the fly, and also for dynamic code creation, as it is often easier to handle the code as a tree of nodes instead of lines of text in complex cases.


While eval only allows you to evaluate a string that contains a single expression, you can eval a whole statement, or even a whole module that has been compiled into bytecode; that is, with Python 2, print is a statement, and cannot be evalled directly:

>>> eval('for i in range(3): print("Python is cool")')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<string>", line 1
    for i in range(3): print("Python is cool")
      ^
SyntaxError: invalid syntax

compile it with 'exec' mode into a code object and you can eval it; the eval function will return None.

>>> code = compile('for i in range(3): print("Python is cool")',
                   'foo.py', 'exec')
>>> eval(code)
Python is cool
Python is cool
Python is cool

If one looks into eval and exec source code in CPython 3, this is very evident; they both call PyEval_EvalCode with same arguments, the only difference being that exec explicitly returns None.

Syntax differences of exec between Python 2 and Python 3

One of the major differences in Python 2 is that exec is a statement and eval is a built-in function (both are built-in functions in Python 3). It is a well-known fact that the official syntax of exec in Python 2 is exec code [in globals[, locals]].

Unlike majority of the Python 2-to-3 porting guides seem to suggest, the exec statement in CPython 2 can be also used with syntax that looks exactly like the exec function invocation in Python 3. The reason is that Python 0.9.9 had the exec(code, globals, locals) built-in function! And that built-in function was replaced with exec statement somewhere before Python 1.0 release.

Since it was desirable to not break backwards compatibility with Python 0.9.9, Guido van Rossum added a compatibility hack in 1993: if the code was a tuple of length 2 or 3, and globals and locals were not passed into the exec statement otherwise, the code would be interpreted as if the 2nd and 3rd element of the tuple were the globals and locals respectively. The compatibility hack was not mentioned even in Python 1.4 documentation (the earliest available version online); and thus was not known to many writers of the porting guides and tools, until it was documented again in November 2012:

The first expression may also be a tuple of length 2 or 3. In this case, the optional parts must be omitted. The form exec(expr, globals) is equivalent to exec expr in globals, while the form exec(expr, globals, locals) is equivalent to exec expr in globals, locals. The tuple form of exec provides compatibility with Python 3, where exec is a function rather than a statement.

Yes, in CPython 2.7 that it is handily referred to as being a forward-compatibility option (why confuse people over that there is a backward compatibility option at all), when it actually had been there for backward-compatibility for two decades.

Thus while exec is a statement in Python 1 and Python 2, and a built-in function in Python 3 and Python 0.9.9,

>>> exec("print(a)", globals(), {'a': 42})
42

has had identical behaviour in possibly every widely released Python version ever; and works in Jython 2.5.2, PyPy 2.3.1 (Python 2.7.6) and IronPython 2.6.1 too (kudos to them following the undocumented behaviour of CPython closely).

What you cannot do in Pythons 1.0 - 2.7 with its compatibility hack, is to store the return value of exec into a variable:

Python 2.7.11+ (default, Apr 17 2016, 14:00:29) 
[GCC 5.3.1 20160413] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a = exec('print(42)')
  File "<stdin>", line 1
    a = exec('print(42)')
           ^
SyntaxError: invalid syntax

(which wouldn't be useful in Python 3 either, as exec always returns None), or pass a reference to exec:

>>> call_later(exec, 'print(42)', delay=1000)
  File "<stdin>", line 1
    call_later(exec, 'print(42)', delay=1000)
                  ^
SyntaxError: invalid syntax

Which a pattern that someone might actually have used, though unlikely;

Or use it in a list comprehension:

>>> [exec(i) for i in ['print(42)', 'print(foo)']
  File "<stdin>", line 1
    [exec(i) for i in ['print(42)', 'print(foo)']
        ^
SyntaxError: invalid syntax

which is abuse of list comprehensions (use a for loop instead!).

Cannot read property 'addEventListener' of null

It seems that document.getElementById('overlayBtn'); is returning null because it executes before the DOM fully loads.

If you put this line of code under

window.onload=function(){
  -- put your code here
}

then it will run without issue.

Example:

window.onload=function(){
    var mb = document.getElementById("b");
    mb.addEventListener("click", handler);
    mb.addEventListener("click", handler2);
}


function handler() {
    $("p").html("<br>" + $("p").text() + "<br>You clicked me-1!<br>");
}

function handler2() {
    $("p").html("<br>" + $("p").text() + "<br>You clicked me-2!<br>");
}

How to add a where clause in a MySQL Insert statement?

In an insert statement you wouldn't have an existing row to do a where claues on? You are inserting a new row, did you mean to do an update statment?

update users set username='JACK' and password='123' WHERE id='1';

How to detect if URL has changed after hash in JavaScript

Another simple way you can do this is by adding a click event, through a class name to the anchor tags on the page to detect when it has been clicked, then you can now use the window.location.href to get the url data which you can use to run your ajax request to the server. Simple and Easy.

Search code inside a Github project

While @VonC's answer works for some repositories, unfortunately for many repositories you can't right now. Github is simply not indexing them (as commented originally by @emddudley). They haven't stated this anywhere on their website, but they will tell you if you ask support:

From: Tim Pease
We have stopped adding newly pushed code into our codesearch index. The volume of code has outgrown our current search index, and we are working on moving to a more scalable search architecture. I'm sorry for the annoyance. We do not have an estimate for when this new search index will be up and running, but when it is ready a blog post will be published (https://github.com/blog).

Annoyingly there is no way to tell which repositories are not indexed other than the lack of results (which also could be from a bad query).

There also is no way to track this issue other than waiting for them to blog it (or watching here on SO).

From: Tim Pease
I am afraid our issue tracker is internal, but we can notify you as soon as the new search index is up and running.

With ng-bind-html-unsafe removed, how do I inject HTML?

I've had a similar problem. Still couldn't get content from my markdown files hosted on github.

After setting up a whitelist (with added github domain) to the $sceDelegateProvider in app.js it worked like a charm.

Description: Using a whitelist instead of wrapping as trusted if you load content from a different urls.

Docs: $sceDelegateProvider and ngInclude (for fetching, compiling and including external HTML fragment)

Positioning <div> element at center of screen

Use flex. Much simpler and will work regardless of your div size:

_x000D_
_x000D_
.center-screen {_x000D_
  display: flex;_x000D_
  flex-direction: column;_x000D_
  justify-content: center;_x000D_
  align-items: center;_x000D_
  text-align: center;_x000D_
  min-height: 100vh;_x000D_
}
_x000D_
 <html>_x000D_
 <head>_x000D_
 </head>_x000D_
 <body>_x000D_
 <div class="center-screen">_x000D_
 I'm in the center_x000D_
 </div>_x000D_
 </body>_x000D_
 </html>
_x000D_
_x000D_
_x000D_

Git On Custom SSH Port

Above answers are nice and great, but not clear for new git users like me. So after some investigation, i offer this new answer.

1 what's the problem with the ssh config file way?

When the config file does not exists, you can create one. Besides port the config file can include other ssh config option:user IdentityFile and so on, the config file looks like

Host mydomain.com
    User git
    Port 12345

If you are running linux, take care the config file must have strict permission: read/write for the user, and not accessible by others

2 what about the ssh url way?

It's cool, the only thing we should know is that there two syntaxes for ssh url in git

  • standard syntax ssh://[user@]host.xz[:port]/path/to/repo.git/
  • scp like syntax [user@]host.xz:path/to/repo.git/

By default Gitlab and Github will show the scp like syntax url, and we can not give the custom ssh port. So in order to change ssh port, we need use the standard syntax

How to enable CORS in AngularJs

Answered by myself.

CORS angular js + restEasy on POST

Well finally I came to this workaround: The reason it worked with IE is because IE sends directly a POST instead of first a preflight request to ask for permission. But I still don't know why the filter wasn't able to manage an OPTIONS request and sends by default headers that aren't described in the filter (seems like an override for that only case ... maybe a restEasy thing ...)

So I created an OPTIONS path in my rest service that rewrites the reponse and includes the headers in the response using response header

I'm still looking for the clean way to do it if anybody faced this before.

Proper use of const for defining functions in JavaScript

There are special cases where arrow functions just won't do the trick:

  1. If we're changing a method of an external API, and need the object's reference.

  2. If we need to use special keywords that are exclusive to the function expression: arguments, yield, bind etc. For more information: Arrow function expression limitations

Example:

I assigned this function as an event handler in the Highcharts API. It's fired by the library, so the this keyword should match a specific object.

export const handleCrosshairHover = function (proceed, e) {
  const axis = this; // axis object
  proceed.apply(axis, Array.prototype.slice.call(arguments, 1)); // method arguments
};

With an arrow function, this would match the declaration scope, and we won't have access to the API obj:

export const handleCrosshairHover = (proceed, e) => {
  const axis = this; // this = undefined
  proceed.apply(axis, Array.prototype.slice.call(arguments, 1)); // compilation error
};

When to use in vs ref vs out

Use out to denote that the parameter is not being used, only set. This helps the caller understand that you're always initializing the parameter.

Also, ref and out are not just for value types. They also let you reset the object that a reference type is referencing from within a method.

Datetime in C# add days

You can add days to a date like this:

// add days to current **DateTime**
var addedDateTime = DateTime.Now.AddDays(10);

// add days to current **Date**
var addedDate = DateTime.Now.Date.AddDays(10);

// add days to any DateTime variable
var addedDateTime = anyDate.AddDay(10);

How to post SOAP Request from PHP

If the XML have identities with same name in different levels there is a solution. You don´t have to ever submit a raw XML (this PHP SOAP object don´t allows send a RAW XML), so you have to always translate your XML to a array, like the example below:

$originalXML = "
<xml>
  <firstClient>
      <name>someone</name>
      <adress>R. 1001</adress>
  </firstClient>
  <secondClient>
      <name>another one</name>
      <adress></adress>
  </secondClient>
</xml>"

//Translate the XML above in a array, like PHP SOAP function requires
$myParams = array('firstClient' => array('name' => 'someone',
                                  'adress' => 'R. 1001'),
            'secondClient' => array('name' => 'another one',
                                  'adress' => ''));

$webService = new SoapClient($someURL);
$result = $webService->someWebServiceFunction($myParams);

or

$soapUrl = "http://privpakservices.schenker.nu/package/package_1.3/packageservices.asmx?op=SearchCollectionPoint";

$xml_post_string = '<?xml version="1.0" encoding="utf-8"?><soap12:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap12="http://www.w3.org/2003/05/soap-envelope"><soap12:Body><SearchCollectionPoint xmlns="http://privpakservices.schenker.nu/"><customerID>XXX</customerID><key>XXXXXX-XXXXXX</key><serviceID></serviceID><paramID>0</paramID><address>RiksvŠgen 5</address><postcode>59018</postcode><city>Mantorp</city><maxhits>10</maxhits></SearchCollectionPoint></soap12:Body></soap12:Envelope>';

$headers = array(
"POST /package/package_1.3/packageservices.asmx HTTP/1.1",
"Host: privpakservices.schenker.nu",
"Content-Type: application/soap+xml; charset=utf-8",
"Content-Length: ".strlen($xml_post_string)
); 

$url = $soapUrl;

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $xml_post_string);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

$response = curl_exec($ch); 
curl_close($ch);

$response1 = str_replace("<soap:Body>","",$response);
$response2 = str_replace("</soap:Body>","",$response1);

$parser = simplexml_load_string($response2);

Why is a ConcurrentModificationException thrown and how to debug it

In Java 8, you can use lambda expression:

map.keySet().removeIf(key -> key condition);

How to apply shell command to each line of a command output?

It's probably easiest to use xargs. In your case:

ls -1 | xargs -L1 echo

The -L flag ensures the input is read properly. From the man page of xargs:

-L number
    Call utility for every number non-empty lines read. 
    A line ending with a space continues to the next non-empty line. [...]

Set CFLAGS and CXXFLAGS options using CMake

You must change the cmake C/CXX default FLAGS .

According to CMAKE_BUILD_TYPE={DEBUG/MINSIZEREL/RELWITHDEBINFO/RELEASE} put in the main CMakeLists.txt one of :

For C

set(CMAKE_C_FLAGS_DEBUG "put your flags")
set(CMAKE_C_FLAGS_MINSIZEREL "put your flags")
set(CMAKE_C_FLAGS_RELWITHDEBINFO "put your flags")
set(CMAKE_C_FLAGS_RELEASE "put your flags")

For C++

set(CMAKE_CXX_FLAGS_DEBUG "put your flags")
set(CMAKE_CXX_FLAGS_MINSIZEREL "put your flags")
set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "put your flags")
set(CMAKE_CXX_FLAGS_RELEASE "put your flags")

This will override the values defined in CMakeCache.txt

PHP Warning: PHP Startup: ????????: Unable to initialize module

Erase the module that can't be initialized and reinstall it.

How to make method call another one in classes?

Because the Method2 is static, all you have to do is call like this:

public class AllMethods
{
    public static void Method2()
    {
        // code here
    }
}

class Caller
{
    public static void Main(string[] args)
    {
        AllMethods.Method2();
    }
}

If they are in different namespaces you will also need to add the namespace of AllMethods to caller.cs in a using statement.

If you wanted to call an instance method (non-static), you'd need an instance of the class to call the method on. For example:

public class MyClass
{
    public void InstanceMethod() 
    { 
        // ...
    }
}

public static void Main(string[] args)
{
    var instance = new MyClass();
    instance.InstanceMethod();
}

Update

As of C# 6, you can now also achieve this with using static directive to call static methods somewhat more gracefully, for example:

// AllMethods.cs
namespace Some.Namespace
{
    public class AllMethods
    {
        public static void Method2()
        {
            // code here
        }
    }
}

// Caller.cs
using static Some.Namespace.AllMethods;

namespace Other.Namespace
{
    class Caller
    {
        public static void Main(string[] args)
        {
            Method2(); // No need to mention AllMethods here
        }
    }
}

Further Reading

Get value of a string after last slash in JavaScript

Jquery:

var afterDot = value.substr(value.lastIndexOf('_') + 1);

Javascript:

var myString = 'asd/f/df/xc/asd/test.jpg'
var parts    = myString.split('/');
var answer   = parts[parts.length - 1];
console.log(answer);

Replace '_' || '/' to your own need

How to call shell commands from Ruby

This explanation is based on a commented Ruby script from a friend of mine. If you want to improve the script, feel free to update it at the link.

First, note that when Ruby calls out to a shell, it typically calls /bin/sh, not Bash. Some Bash syntax is not supported by /bin/sh on all systems.

Here are ways to execute a shell script:

cmd = "echo 'hi'" # Sample string that can be used
  1. Kernel#` , commonly called backticks – `cmd`

    This is like many other languages, including Bash, PHP, and Perl.

    Returns the result (i.e. standard output) of the shell command.

    Docs: http://ruby-doc.org/core/Kernel.html#method-i-60

    value = `echo 'hi'`
    value = `#{cmd}`
    
  2. Built-in syntax, %x( cmd )

    Following the x character is a delimiter, which can be any character. If the delimiter is one of the characters (, [, {, or <, the literal consists of the characters up to the matching closing delimiter, taking account of nested delimiter pairs. For all other delimiters, the literal comprises the characters up to the next occurrence of the delimiter character. String interpolation #{ ... } is allowed.

    Returns the result (i.e. standard output) of the shell command, just like the backticks.

    Docs: https://docs.ruby-lang.org/en/master/syntax/literals_rdoc.html#label-Percent+Strings

    value = %x( echo 'hi' )
    value = %x[ #{cmd} ]
    
  3. Kernel#system

    Executes the given command in a subshell.

    Returns true if the command was found and run successfully, false otherwise.

    Docs: http://ruby-doc.org/core/Kernel.html#method-i-system

    wasGood = system( "echo 'hi'" )
    wasGood = system( cmd )
    
  4. Kernel#exec

    Replaces the current process by running the given external command.

    Returns none, the current process is replaced and never continues.

    Docs: http://ruby-doc.org/core/Kernel.html#method-i-exec

    exec( "echo 'hi'" )
    exec( cmd ) # Note: this will never be reached because of the line above
    

Here's some extra advice: $?, which is the same as $CHILD_STATUS, accesses the status of the last system executed command if you use the backticks, system() or %x{}. You can then access the exitstatus and pid properties:

$?.exitstatus

For more reading see:

how to add picasso library in android studio

Dependency

dependencies {

   implementation 'com.squareup.picasso:picasso:2.71828'

}

//Java Code for Image Loading into imageView

Picasso.get().load(werURL).into(imageView);

Swift Open Link in Safari

Swift 5

if let url = URL(string: "https://www.google.com") {
    UIApplication.shared.open(url)
}

Redirect to a page/URL after alert button is pressed

Like that, both of the sentences will be executed even before the page has finished loading.

Here is your error, you are missing a ';' Change:

       echo 'alert("review your answer")'; 
       echo 'window.location= "index.php"';

To:

       echo 'alert("review your answer");';
       echo 'window.location= "index.php";';

Then a suggestion: You really should trigger that logic after some event. So, for instance:

           document.getElementById("myBtn").onclick=function(){
                 alert("review your answer");
                 window.location= "index.php";
           };

Another suggestion, use jQuery

git clone through ssh

This is possibly unrelated directly to the question; but one mistake I just made myself, and I see in the OP, is the URL specification ssh://user@server:/GitRepos/myproject.git - namely, you have both a colon :, and a forward slash / after it signifying an absolute path.

I then found Git clone, ssh: Could not resolve hostname – git , development – Nicolas Kuttler (as that was the error I was getting, on git version 1.7.9.5), noting:

The problem with the command I used initially was that I tried to use an scp-like syntax.

... which was also my problem! So basically in git with ssh, you either use

  • ssh://[email protected]/absolute/path/to/repo.git/ - just a forward slash for absolute path on server
  • [email protected]:relative/path/to/repo.git/ - just a colon (it mustn't have the ssh:// for relative path on server (relative to home dir of username on server machine)

Hope this helps someone,
Cheers!

laravel select where and where condition

$this->where('email', $email)->where('password', $password) 

is returning a Builder object which you could use to append more where filters etc.

To get the result you need:

$userRecord = $this->where('email', $email)->where('password', $password)->first();

Check that a variable is a number in UNIX shell

Shell variables have no type, so the simplest way is to use the return type test command:

if [ $var -eq $var 2> /dev/null ]; then ...

(Or else parse it with a regexp)

Saving Excel workbook to constant path with filename from two fields

Ok, at that time got it done with the help of a friend and the code looks like this.

Sub Saving()

Dim part1 As String

Dim part2 As String


part1 = Range("C5").Value

part2 = Range("C8").Value


ActiveWorkbook.SaveAs Filename:= _

"C:\-docs\cmat\Desktop\pieteikumi\" & part1 & " " & part2 & ".xlsm", FileFormat:= _
xlOpenXMLWorkbookMacroEnabled, CreateBackup:=False

End Sub

How do I edit this part (FileFormat:= _ xlOpenXMLWorkbookMacroEnabled) for it to save as Excel 97-2013 Workbook, have tried several variations with no success. Thankyou

Seems, that I found the solution, but my idea is flawed. By doing this FileFormat:= _ xlOpenXMLWorkbook, it drops out a popup saying, the you cannot save this workbook as a file without Macro enabled. So, is this impossible?

Is there a C# case insensitive equals operator?

You can use

if (stringA.equals(StringB, StringComparison.CurrentCultureIgnoreCase))

Python concatenate text files

This should do it

For large files:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            for line in infile:
                outfile.write(line)

For small files:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            outfile.write(infile.read())

… and another interesting one that I thought of:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for line in itertools.chain.from_iterable(itertools.imap(open, filnames)):
        outfile.write(line)

Sadly, this last method leaves a few open file descriptors, which the GC should take care of anyway. I just thought it was interesting

Understanding the basics of Git and GitHub

  1. What is the difference between Git and GitHub?

    Linus Torvalds would kill you for this. Git is the name of the version manager program he wrote. GitHub is a website on which there are source code repositories manageable by Git. Thus, GitHub is completely unrelated to the original Git tool.

  2. Is git saving every repository locally (in the user's machine) and in GitHub?

    If you commit changes, it stores locally. Then, if you push the commits, it also sotres them remotely.

  3. Can you use Git without GitHub? If yes, what would be the benefit for using GitHub?

    You can, but I'm sure you don't want to manually set up a git server for yourself. Benefits of GitHub? Well, easy to use, lot of people know it so others may find your code and follow/fork it to make improvements as well.

  4. How does Git compare to a backup system such as Time Machine?

    Git is specifically designed and optimized for source code.

  5. Is this a manual process, in other words if you don't commit you wont have a new version of the changes made?

    Exactly.

  6. If are not collaborating and you are already using a backup system why would you use Git?

    See #4.

how to achieve transfer file between client and server using java socket

Reading quickly through the source it seems that you're not far off. The following link should help (I did something similar but for FTP). For a file send from server to client, you start off with a file instance and an array of bytes. You then read the File into the byte array and write the byte array to the OutputStream which corresponds with the InputStream on the client's side.

http://www.rgagnon.com/javadetails/java-0542.html

Edit: Here's a working ultra-minimalistic file sender and receiver. Make sure you understand what the code is doing on both sides.

package filesendtest;

import java.io.*;
import java.net.*;

class TCPServer {

    private final static String fileToSend = "C:\\test1.pdf";

    public static void main(String args[]) {

        while (true) {
            ServerSocket welcomeSocket = null;
            Socket connectionSocket = null;
            BufferedOutputStream outToClient = null;

            try {
                welcomeSocket = new ServerSocket(3248);
                connectionSocket = welcomeSocket.accept();
                outToClient = new BufferedOutputStream(connectionSocket.getOutputStream());
            } catch (IOException ex) {
                // Do exception handling
            }

            if (outToClient != null) {
                File myFile = new File( fileToSend );
                byte[] mybytearray = new byte[(int) myFile.length()];

                FileInputStream fis = null;

                try {
                    fis = new FileInputStream(myFile);
                } catch (FileNotFoundException ex) {
                    // Do exception handling
                }
                BufferedInputStream bis = new BufferedInputStream(fis);

                try {
                    bis.read(mybytearray, 0, mybytearray.length);
                    outToClient.write(mybytearray, 0, mybytearray.length);
                    outToClient.flush();
                    outToClient.close();
                    connectionSocket.close();

                    // File sent, exit the main method
                    return;
                } catch (IOException ex) {
                    // Do exception handling
                }
            }
        }
    }
}

package filesendtest;

import java.io.*;
import java.io.ByteArrayOutputStream;
import java.net.*;

class TCPClient {

    private final static String serverIP = "127.0.0.1";
    private final static int serverPort = 3248;
    private final static String fileOutput = "C:\\testout.pdf";

    public static void main(String args[]) {
        byte[] aByte = new byte[1];
        int bytesRead;

        Socket clientSocket = null;
        InputStream is = null;

        try {
            clientSocket = new Socket( serverIP , serverPort );
            is = clientSocket.getInputStream();
        } catch (IOException ex) {
            // Do exception handling
        }

        ByteArrayOutputStream baos = new ByteArrayOutputStream();

        if (is != null) {

            FileOutputStream fos = null;
            BufferedOutputStream bos = null;
            try {
                fos = new FileOutputStream( fileOutput );
                bos = new BufferedOutputStream(fos);
                bytesRead = is.read(aByte, 0, aByte.length);

                do {
                        baos.write(aByte);
                        bytesRead = is.read(aByte);
                } while (bytesRead != -1);

                bos.write(baos.toByteArray());
                bos.flush();
                bos.close();
                clientSocket.close();
            } catch (IOException ex) {
                // Do exception handling
            }
        }
    }
}

Related

Byte array of unknown length in java

Edit: The following could be used to fingerprint small files before and after transfer (use SHA if you feel it's necessary):

public static String md5String(File file) {
    try {
        InputStream fin = new FileInputStream(file);
        java.security.MessageDigest md5er = MessageDigest.getInstance("MD5");
        byte[] buffer = new byte[1024];
        int read;
        do {
            read = fin.read(buffer);
            if (read > 0) {
                md5er.update(buffer, 0, read);
            }
        } while (read != -1);
        fin.close();
        byte[] digest = md5er.digest();
        if (digest == null) {
            return null;
        }
        String strDigest = "0x";
        for (int i = 0; i < digest.length; i++) {
            strDigest += Integer.toString((digest[i] & 0xff)
                    + 0x100, 16).substring(1).toUpperCase();
        }
        return strDigest;
    } catch (Exception e) {
        return null;
    }
}

Style child element when hover on parent

you can use this too

_x000D_
_x000D_
.parent:hover * {
   /* ... */
}
_x000D_
_x000D_
_x000D_

SaveFileDialog setting default path and file type?

Here's an example that actually filters for BIN files. Also Windows now want you to save files to user locations, not system locations, so here's an example (you can use intellisense to browse the other options):

            var saveFileDialog = new Microsoft.Win32.SaveFileDialog()
            {
                DefaultExt = "*.xml",
                Filter = "BIN Files (*.bin)|*.bin",
                InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments),
            };

            var result = saveFileDialog.ShowDialog();
            if (result != null && result == true)
            {
                // Save the file here
            }

Class JavaLaunchHelper is implemented in both ... libinstrument.dylib. One of the two will be used. Which one is undefined

Not sure if this is the cause of the problem, but I got this issue only after installing JVM Monitor.

Uninstalling JVM Monitor solved the issue for me.

XML Carriage return encoding

To insert a CR into XML, you need to use its character entity &#13;.

This is because compliant XML parsers must, before parsing, translate CRLF and any CR not followed by a LF to a single LF. This behavior is defined in the End-of-Line handling section of the XML 1.0 specification.

How can I get double quotes into a string literal?

Escape the quotes with backslashes:

printf("She said \"time flies like an arrow, but fruit flies like a banana\"."); 

There are special escape characters that you can use in string literals, and these are denoted with a leading backslash.

Getting "A potentially dangerous Request.Path value was detected from the client (&)"

We were getting this same error in Fiddler when trying to figure out why our Silverlight ArcGIS map viewer wasn't loading the map. In our case it was a typo in the URL in the code. There was an equal sign in there for some reason.
http:=//someurltosome/awesome/place
instead of
http://someurltosome/awesome/place

After taking out that equal sign it worked great (of course).

What is the difference between supervised learning and unsupervised learning?

Supervised Learning: You have labeled data and have to learn from that. e.g house data along with price and then learn to predict price

Unsupervised learning: you have to find the trend and then predict, no prior labels given. e.g different people in the class and then a new person comes so what group does this new student belong to.

Android check null or empty string in Android

From @Jon Skeet comment, really the String value is "null". Following code solved it

if (userEmail != null && !userEmail.isEmpty() && !userEmail.equals("null")) 

How to show shadow around the linearlayout in Android?

Well, this is easy to achieve .

Just build a GradientDrawable that comes from black and goes to a transparent color, than use parent relationship to place your shape close to the View that you want to have a shadow, then you just have to give any values to height or width .

Here is an example, this file have to be created inside res/drawable , I name it as shadow.xml :

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <gradient
        android:startColor="#9444"
        android:endColor="#0000"
        android:type="linear"
        android:angle="90"> <!-- Change this value to have the correct shadow angle, must be multiple from 45 -->
    </gradient>

</shape>

Place the following code above from a LinearLayout , for example, set the android:layout_width and android:layout_height to fill_parent and 2.3dp, you'll have a nice shadow effect on your LinearLayout .

<View
    android:id="@+id/shadow"
    android:layout_width="fill_parent"
    android:layout_height="2.3dp"  
    android:layout_above="@+id/id_from_your_LinearLayout" 
    android:background="@drawable/shadow">
</View>

Note 1: If you increase android:layout_height more shadow will be shown .

Note 2: Use android:layout_above="@+id/id_from_your_LinearLayout" attribute if you are placing this code inside a RelativeLayout, otherwise ignore it.

Hope it help someone.

How to check for changes on remote (origin) Git repository

One potential solution

Thanks to Alan Haggai Alavi's solution I came up with the following potential workflow:

Step 1:

git fetch origin

Step 2:

git checkout -b localTempOfOriginMaster origin/master
git difftool HEAD~3 HEAD~2
git difftool HEAD~2 HEAD~1
git difftool HEAD~1 HEAD~0

Step 3:

git checkout master
git branch -D localTempOfOriginMaster
git merge origin/master

How to add google-play-services.jar project dependency so my project will run and present map

The quick start guide that keyboardsurfer references will work if you need to get your project to build properly, but it leaves you with a dummy google-play-services project in your Eclipse workspace, and it doesn't properly link Eclipse to the Google Play Services Javadocs.

Here's what I did instead:

  1. Install the Google Play Services SDK using the instructions in the Android Maps V2 Quick Start referenced above, or the instructions to Setup Google Play Services SDK, but do not follow the instructions to add Google Play Services into your project.

  2. Right click on the project in the Package Explorer, select Properties to open the properties for your project.

  3. (Only if you already followed the instructions in the quick start guide!) Remove the dependency on the google-play-services project:

    • Click on the Android category and remove the reference to the google-play-services project.

    • Click on the Java Build Path category, then the Projects tab and remove the reference to the google-play-services project.

  4. Click on the Java Build Path category, then the Libraries tab.

  5. Click Add External JARs... and select the google-play-services.jar file. This should be in [Your ADT directory]\sdk\extras\google\google_play_services\libproject\google-play-services_lib\libs.

  6. Click on the arrow next to the new google-play-services.jar entry, and select the Javadoc Location item.

  7. Click Edit... and select the folder containing the Google Play Services Javadocs. This should be in [Your ADT directory]\sdk\extras\google\google_play_services\docs\reference.

  8. Still in the Java Build Path category, click on the Order and Export tab. Check the box next to the google-play-services.jar entry.

  9. Click OK to save your project properties.

Your project should now have access to the Google Play Services library, and the Javadocs should display properly in Eclipse.

C# equivalent to Java's charAt()?

please try to make it as a character

string str = "Tigger";
//then str[0] will return 'T' not "T"

How to execute only one test spec with angular-cli

Just small change need in test.ts file inside src folder:

const context = require.context('./', true, /test-example\.spec\.ts$/);

Here, test-example is the exact file name which we need to run

In the same way, if you need to test the service file only you can replace the filename like "/test-example.service"

Scheduled run of stored procedure on SQL server

Yes, in MS SQL Server, you can create scheduled jobs. In SQL Management Studio, navigate to the server, then expand the SQL Server Agent item, and finally the Jobs folder to view, edit, add scheduled jobs.

Find a string within a cell using VBA

you never change the value of rng so it always points to the initial cell

copy the Set rng = rng.Offset(1, 0) to a new line before loop

also, your InStr test will always fail
True is -1, but the return from InStr will be greater than 0 when the string is found. change the test to remove = True

new code:

Sub IfTest()
 'This should split the information in a table up into cells
 Dim Splitter() As String
 Dim LenValue As Integer     'Gives the number of characters in date string
 Dim LeftValue As Integer    'One less than the LenValue to drop the ")"
 Dim rng As Range, cell As Range
 Set rng = ActiveCell

Do While ActiveCell.Value <> Empty
    If InStr(rng, "%") Then
        ActiveCell.Offset(0, 0).Select
        Splitter = Split(ActiveCell.Value, "% Change")
        ActiveCell.Offset(0, 10).Select
        ActiveCell.Value = Splitter(1)
        ActiveCell.Offset(0, -1).Select
        ActiveCell.Value = "% Change"
        ActiveCell.Offset(1, -9).Select
    Else
        ActiveCell.Offset(0, 0).Select
        Splitter = Split(ActiveCell.Value, "(")
        ActiveCell.Offset(0, 9).Select
        ActiveCell.Value = Splitter(0)
        ActiveCell.Offset(0, 1).Select
        LenValue = Len(Splitter(1))
        LeftValue = LenValue - 1
        ActiveCell.Value = Left(Splitter(1), LeftValue)
        ActiveCell.Offset(1, -10).Select
    End If
Set rng = rng.Offset(1, 0)
Loop

End Sub

How to remove all debug logging calls before building the release version of an Android app?

Christopher's Proguard solution is the best, but if for any reason you don't like Proguard, here is a very low-tech solution:

Comment logs:

find . -name "*\.java" | xargs grep -l 'Log\.' | xargs sed -i 's/Log\./;\/\/ Log\./g'

Uncomment logs:

find . -name "*\.java" | xargs grep -l 'Log\.' | xargs sed -i 's/;\/\/ Log\./Log\./g'

A constraint is that your logging instructions must not span over multiple lines.

(Execute these lines in a UNIX shell at the root of your project. If using Windows, get a UNIX layer or use equivalent Windows commands)

How do I specify different layouts for portrait and landscape orientations?

Create a new directory layout-land, then create xml file with same name in layout-land as it was layout directory and align there your content for Landscape mode.

Note that id of content in both xml is same.

Finding the mode of a list

I wrote up this handy function to find the mode.

def mode(nums):
    corresponding={}
    occurances=[]
    for i in nums:
            count = nums.count(i)
            corresponding.update({i:count})

    for i in corresponding:
            freq=corresponding[i]
            occurances.append(freq)

    maxFreq=max(occurances)

    keys=corresponding.keys()
    values=corresponding.values()

    index_v = values.index(maxFreq)
    global mode
    mode = keys[index_v]
    return mode

String contains another two strings

string d = "You hit someone for 50 damage";
string a = "damage";
string b = "someone";
string c = "you";

if(d.Contains(a) && d.Contains(b))
{
    Console.WriteLine(" " + d);
}
Console.ReadLine();

Show/Hide Div on Scroll

Try this code

$('window').scrollDown(function(){$(#div).hide()});

$('window').scrollUp(function(){ $(#div).show() });

How can I select an element in a component template?

For people trying to grab the component instance inside a *ngIf or *ngSwitchCase, you can follow this trick.

Create an init directive.

import {
    Directive,
    EventEmitter,
    Output,
    OnInit,
    ElementRef
} from '@angular/core';

@Directive({
    selector: '[init]'
})
export class InitDirective implements OnInit {
    constructor(private ref: ElementRef) {}

    @Output() init: EventEmitter<ElementRef> = new EventEmitter<ElementRef>();

    ngOnInit() {
        this.init.emit(this.ref);
    }
}

Export your component with a name such as myComponent

@Component({
    selector: 'wm-my-component',
    templateUrl: 'my-component.component.html',
    styleUrls: ['my-component.component.css'],
    exportAs: 'myComponent'
})
export class MyComponent { ... }

Use this template to get the ElementRef AND MyComponent instance

<div [ngSwitch]="type">
    <wm-my-component
           #myComponent="myComponent"
           *ngSwitchCase="Type.MyType"
           (init)="init($event, myComponent)">
    </wm-my-component>
</div>

Use this code in TypeScript

init(myComponentRef: ElementRef, myComponent: MyComponent) {
}

C# Double - ToString() formatting with two decimal places but no rounding

I suggest you truncate first, and then format:

double a = 123.4567;
double aTruncated = Math.Truncate(a * 100) / 100;
CultureInfo ci = new CultureInfo("de-DE");
string s = string.Format(ci, "{0:0.00}%", aTruncated);

Use the constant 100 for 2 digits truncate; use a 1 followed by as many zeros as digits after the decimal point you would like. Use the culture name you need to adjust the formatting result.

Changes in import statement python3

Relative import happens whenever you are importing a package relative to the current script/package.

Consider the following tree for example:

mypkg
+-- base.py
+-- derived.py

Now, your derived.py requires something from base.py. In Python 2, you could do it like this (in derived.py):

from base import BaseThing

Python 3 no longer supports that since it's not explicit whether you want the 'relative' or 'absolute' base. In other words, if there was a Python package named base installed in the system, you'd get the wrong one.

Instead it requires you to use explicit imports which explicitly specify location of a module on a path-alike basis. Your derived.py would look like:

from .base import BaseThing

The leading . says 'import base from module directory'; in other words, .base maps to ./base.py.

Similarly, there is .. prefix which goes up the directory hierarchy like ../ (with ..mod mapping to ../mod.py), and then ... which goes two levels up (../../mod.py) and so on.

Please however note that the relative paths listed above were relative to directory where current module (derived.py) resides in, not the current working directory.


@BrenBarn has already explained the star import case. For completeness, I will have to say the same ;).

For example, you need to use a few math functions but you use them only in a single function. In Python 2 you were permitted to be semi-lazy:

def sin_degrees(x):
    from math import *
    return sin(degrees(x))

Note that it already triggers a warning in Python 2:

a.py:1: SyntaxWarning: import * only allowed at module level
  def sin_degrees(x):

In modern Python 2 code you should and in Python 3 you have to do either:

def sin_degrees(x):
    from math import sin, degrees
    return sin(degrees(x))

or:

from math import *

def sin_degrees(x):
    return sin(degrees(x))

Echoing the last command run in Bash?

I was able to achieve this by using set -x in the main script (which makes the script print out every command that is executed) and writing a wrapper script which just shows the last line of output generated by set -x.

This is the main script:

#!/bin/bash
set -x
echo some command here
echo last command

And this is the wrapper script:

#!/bin/sh
./test.sh 2>&1 | grep '^\+' | tail -n 1 | sed -e 's/^\+ //'

Running the wrapper script produces this as output:

echo last command

Deprecated Gradle features were used in this build, making it incompatible with Gradle 5.0

In my case adding multiDexEnabled true in Android/build/build.gradle file compiled the files.

I will look into removing this in the future, as in the documentation it says 'Before configuring your app to enable use of 64K or more method references, you should take steps to reduce the total number of references called by your app code, including methods defined by your app code or included libraries.'

defaultConfig {
  applicationId "com.peoplesenergyapp"
  minSdkVersion rootProject.ext.minSdkVersion
  targetSdkVersion rootProject.ext.targetSdkVersion
  versionCode 1
  versionName "1.0"
  multiDexEnabled true // <-add this 
}

Sticky and NON-Sticky sessions

When your website is served by only one web server, for each client-server pair, a session object is created and remains in the memory of the web server. All the requests from the client go to this web server and update this session object. If some data needs to be stored in the session object over the period of interaction, it is stored in this session object and stays there as long as the session exists.

However, if your website is served by multiple web servers which sit behind a load balancer, the load balancer decides which actual (physical) web-server should each request go to. For example, if there are 3 web servers A, B and C behind the load balancer, it is possible that www.mywebsite.com/index.jsp is served from server A, www.mywebsite.com/login.jsp is served from server B and www.mywebsite.com/accoutdetails.php are served from server C.

Now, if the requests are being served from (physically) 3 different servers, each server has created a session object for you and because these session objects sit on three independent boxes, there's no direct way of one knowing what is there in the session object of the other. In order to synchronize between these server sessions, you may have to write/read the session data into a layer which is common to all - like a DB. Now writing and reading data to/from a db for this use-case may not be a good idea. Now, here comes the role of sticky-session.

If the load balancer is instructed to use sticky sessions, all of your interactions will happen with the same physical server, even though other servers are present. Thus, your session object will be the same throughout your entire interaction with this website.

To summarize, In case of Sticky Sessions, all your requests will be directed to the same physical web server while in case of a non-sticky loadbalancer may choose any webserver to serve your requests.

As an example, you may read about Amazon's Elastic Load Balancer and sticky sessions here : http://aws.typepad.com/aws/2010/04/new-elastic-load-balancing-feature-sticky-sessions.html

Fastest way to convert an iterator to a list

since python 3.5 you can use * iterable unpacking operator:

user_list = [*your_iterator]

but the pythonic way to do it is:

user_list  = list(your_iterator)

How to convert a Java 8 Stream to an Array?

     Stream<Integer> stream = Stream.of(1, 2, 3, 4, 5, 6);

     Integer[] integers = stream.toArray(it->new Integer[it]);

How to change Elasticsearch max memory size

If you use windows server, you can change Environment Variable, restart server to apply new Environment Value and start Elastic Service. More detail in Install Elastic in Windows Server

Vector of Vectors to create matrix

I'm not familiar with c++, but a quick look at the documentation suggests that this should work:

//cin>>CC; cin>>RR; already done
vector<vector<int> > matrix;
for(int i = 0; i<RR; i++)
{
    vector<int> myvector;
    for(int j = 0; j<CC; j++)
    {
        int tempVal = 0;
        cout<<"Enter the number for Matrix 1";
        cin>>tempVal;
        myvector.push_back(tempVal);
    }
    matrix.push_back(myvector);
}

Why can't DateTime.ParseExact() parse "9/1/2009" using "M/d/yyyy"

try this

provider = new CultureInfo("en-US");
DateTime.ParseExact("9/1/2009", "M/d/yyyy", provider);

Bye.

How to check if a file exists in the Documents directory in Swift?

This works fine for me in swift4:

func existingFile(fileName: String) -> Bool {

    let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
    let url = NSURL(fileURLWithPath: path)
    if let pathComponent = url.appendingPathComponent("\(fileName)") {
        let filePath = pathComponent.path
        let fileManager = FileManager.default
        if fileManager.fileExists(atPath: filePath) 

       {

        return true

        } else {

        return false

        }

    } else {

        return false

        }


}

You can check with this call:

   if existingFile(fileName: "yourfilename") == true {

            // your code if file exists

           } else {

           // your code if file does not exist

           }

I hope it is useful for someone. @;-]

Get the cartesian product of a series of lists?

Although there are many answers already, I would like to share some of my thoughts:

Iterative approach

def cartesian_iterative(pools):
  result = [[]]
  for pool in pools:
    result = [x+[y] for x in result for y in pool]
  return result

Recursive Approach

def cartesian_recursive(pools):
  if len(pools) > 2:
    pools[0] = product(pools[0], pools[1])
    del pools[1]
    return cartesian_recursive(pools)
  else:
    pools[0] = product(pools[0], pools[1])
    del pools[1]
    return pools
def product(x, y):
  return [xx + [yy] if isinstance(xx, list) else [xx] + [yy] for xx in x for yy in y]

Lambda Approach

def cartesian_reduct(pools):
  return reduce(lambda x,y: product(x,y) , pools)

Passing additional variables from command line to make

From the manual:

Variables in make can come from the environment in which make is run. Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. However, an explicit assignment in the makefile, or with a command argument, overrides the environment.

So you can do (from bash):

FOOBAR=1 make

resulting in a variable FOOBAR in your Makefile.

Embedding DLLs in a compiled executable

Another product that can handle this elegantly is SmartAssembly, at SmartAssembly.com. This product will, in addition to merging all dependencies into a single DLL, (optionally) obfuscate your code, remove extra meta-data to reduce the resulting file size, and can also actually optimize the IL to increase runtime performance.

There is also some kind of global exception handling/reporting feature it adds to your software (if desired) that could be useful. I believe it also has a command-line API so you can make it part of your build process.

Initialising an array of fixed size in python

One thing I find easy to do is i set an array of empty strings for the size I prefer, for example

Code:

import numpy as np

x= np.zeros(5,str)
print x

Output:

['' '' '' '' '']

Hope this is helpful :)

powershell 2.0 try catch how to access the exception

Try something like this:

try {
    $w = New-Object net.WebClient
    $d = $w.downloadString('http://foo')
}
catch [Net.WebException] {
    Write-Host $_.Exception.ToString()
}

The exception is in the $_ variable. You might explore $_ like this:

try {
    $w = New-Object net.WebClient
    $d = $w.downloadString('http://foo')
}
catch [Net.WebException] {
    $_ | fl * -Force
}

I think it will give you all the info you need.

My rule: if there is some data that is not displayed, try to use -force.

Output single character in C

yes, %c will print a single char:

printf("%c", 'h');

also, putchar/putc will work too. From "man putchar":

#include <stdio.h>

int fputc(int c, FILE *stream);
int putc(int c, FILE *stream);
int putchar(int c);

* fputc() writes the character c, cast to an unsigned char, to stream.
* putc() is equivalent to fputc() except that it may be implemented as a macro which evaluates stream more than once.
* putchar(c); is equivalent to putc(c,stdout).

EDIT:

Also note, that if you have a string, to output a single char, you need get the character in the string that you want to output. For example:

const char *h = "hello world";
printf("%c\n", h[4]); /* outputs an 'o' character */

Gson: Is there an easier way to serialize a map

Map<String, Object> config = gson.fromJson(reader, Map.class);

MySQL - Cannot add or update a child row: a foreign key constraint fails

My fix for this was my child table needed to be populated before the parent table.

I had two tables: UserDetails and Login linked by an email address. I therefore had to insert into the UserDetails first before inserting into the Login table:

insert into UserDetails (Email, Name, Telephone, Department) values ('Email', 'Name', 'number', 'IT');

Then:

insert into Login (UserID, UserType, Email, Username, Password) VALUES (001, 'SYS-USR-ADMIN', 'Email', 'Name', 'Password')

Getting user input

sys.argv[0] is not the first argument but the filename of the python program you are currently executing. I think you want sys.argv[1]

How to split/partition a dataset into training and test datasets for, e.g., cross validation?

Likely you will not only need to split into train and test, but also cross validation to make sure your model generalizes. Here I am assuming 70% training data, 20% validation and 10% holdout/test data.

Check out the np.split:

If indices_or_sections is a 1-D array of sorted integers, the entries indicate where along axis the array is split. For example, [2, 3] would, for axis=0, result in

ary[:2] ary[2:3] ary[3:]

t, v, h = np.split(df.sample(frac=1, random_state=1), [int(0.7*len(df)), int(0.9*len(df))]) 

Difference between numpy dot() and Python 3.5+ matrix multiplication @

Just FYI, @ and its numpy equivalents dot and matmul are all equally fast. (Plot created with perfplot, a project of mine.)

enter image description here

Code to reproduce the plot:

import perfplot
import numpy


def setup(n):
    A = numpy.random.rand(n, n)
    x = numpy.random.rand(n)
    return A, x


def at(data):
    A, x = data
    return A @ x


def numpy_dot(data):
    A, x = data
    return numpy.dot(A, x)


def numpy_matmul(data):
    A, x = data
    return numpy.matmul(A, x)


perfplot.show(
    setup=setup,
    kernels=[at, numpy_dot, numpy_matmul],
    n_range=[2 ** k for k in range(15)],
)

How can I output leading zeros in Ruby?

filenames = '000'.upto('100').map { |index| "file_#{index}" }

Outputs

[file_000, file_001, file_002, file_003, ..., file_098, file_099, file_100]

What svn command would list all the files modified on a branch?

echo You must invoke st from within branch directory
SvnUrl=`svn info | grep URL | sed 's/URL: //'`
SvnVer=`svn info | grep Revision | sed 's/Revision: //'`
svn diff -r $SvnVer --summarize $SvnUrl

Jboss server error : Failed to start service jboss.deployment.unit."jbpm-console.war"

  1. delete your project folder under C:\....\wildfly-9.0.1.Final\standalone\deployments\YOUR-PROJEKT-FOLDER
  2. restart your wildfly-server

Get Android API level of phone currently running my application

try this :Float.valueOf(android.os.Build.VERSION.RELEASE) <= 2.1

How to extract numbers from a string in Python?

If you know it will be only one number in the string, i.e 'hello 12 hi', you can try filter.

For example:

In [1]: int(''.join(filter(str.isdigit, '200 grams')))
Out[1]: 200
In [2]: int(''.join(filter(str.isdigit, 'Counters: 55')))
Out[2]: 55
In [3]: int(''.join(filter(str.isdigit, 'more than 23 times')))
Out[3]: 23

But be carefull !!! :

In [4]: int(''.join(filter(str.isdigit, '200 grams 5')))
Out[4]: 2005

Delete all rows in an HTML table

Assign an id or a class for your tbody.

document.querySelector("#tbodyId").remove();
document.querySelectorAll(".tbodyClass").remove();

You can name your id or class how you want, not necessarily #tbodyId or .tbodyClass.

Change background image opacity

and you can do that by simple code:

filter:alpha(opacity=30);
-moz-opacity:0.3;
-khtml-opacity: 0.3;
opacity: 0.3;

Can I use GDB to debug a running process?

Yes. Use the attach command. Check out this link for more information. Typing help attach at a GDB console gives the following:

(gdb) help attach

Attach to a process or file outside of GDB. This command attaches to another target, of the same type as your last "target" command ("info files" will show your target stack). The command may take as argument a process id, a process name (with an optional process-id as a suffix), or a device file. For a process id, you must have permission to send the process a signal, and it must have the same effective uid as the debugger. When using "attach" to an existing process, the debugger finds the program running in the process, looking first in the current working directory, or (if not found there) using the source file search path (see the "directory" command). You can also use the "file" command to specify the program, and to load its symbol table.


NOTE: You may have difficulty attaching to a process due to improved security in the Linux kernel - for example attaching to the child of one shell from another.

You'll likely need to set /proc/sys/kernel/yama/ptrace_scope depending on your requirements. Many systems now default to 1 or higher.

The sysctl settings (writable only with CAP_SYS_PTRACE) are:

0 - classic ptrace permissions: a process can PTRACE_ATTACH to any other
    process running under the same uid, as long as it is dumpable (i.e.
    did not transition uids, start privileged, or have called
    prctl(PR_SET_DUMPABLE...) already). Similarly, PTRACE_TRACEME is
    unchanged.

1 - restricted ptrace: a process must have a predefined relationship
    with the inferior it wants to call PTRACE_ATTACH on. By default,
    this relationship is that of only its descendants when the above
    classic criteria is also met. To change the relationship, an
    inferior can call prctl(PR_SET_PTRACER, debugger, ...) to declare
    an allowed debugger PID to call PTRACE_ATTACH on the inferior.
    Using PTRACE_TRACEME is unchanged.

2 - admin-only attach: only processes with CAP_SYS_PTRACE may use ptrace
    with PTRACE_ATTACH, or through children calling PTRACE_TRACEME.

3 - no attach: no processes may use ptrace with PTRACE_ATTACH nor via
    PTRACE_TRACEME. Once set, this sysctl value cannot be changed.

The type is defined in an assembly that is not referenced, how to find the cause?

The type 'Domain.tblUser' is defined in an assembly that is not referenced. You must add a reference to assembly 'Domain, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

**Solved:**
 Add reference of my domain library layer to my web app libary layer

Note: Make sure your references are correct according to you DI container

Vuex - Computed property "name" was assigned to but it has no setter

If you're going to v-model a computed, it needs a setter. Whatever you want it to do with the updated value (probably write it to the $store, considering that's what your getter pulls it from) you do in the setter.

If writing it back to the store happens via form submission, you don't want to v-model, you just want to set :value.

If you want to have an intermediate state, where it's saved somewhere but doesn't overwrite the source in the $store until form submission, you'll need to create such a data item.

How can I find the number of days between two Date objects in Ruby?

This may have changed in Ruby 2.0

When I do this I get a fraction. For example on the console (either irb or rails c)

2.0.0-p195 :005 > require 'date'
 => true 
2.0.0-p195 :006 >  a_date = Date.parse("25/12/2013")
 => #<Date: 2013-12-25 ((2456652j,0s,0n),+0s,2299161j)> 
2.0.0-p195 :007 >  b_date = Date.parse("10/12/2013")
 => #<Date: 2013-12-10 ((2456637j,0s,0n),+0s,2299161j)> 
2.0.0-p195 :008 > a_date-b_date
 => (15/1) 

Of course, casting to an int give the expected result

2.0.0-p195 :009 > (a_date-b_date).to_i
 => 15 

This also works for DateTime objects, but you have to take into consideration seconds, such as this example

2.0.0-p195 :017 >   a_date_time = DateTime.now
 => #<DateTime: 2013-12-31T12:23:03-08:00 ((2456658j,73383s,725757000n),-28800s,2299161j)> 
2.0.0-p195 :018 > b_date_time = DateTime.now-20
 => #<DateTime: 2013-12-11T12:23:06-08:00 ((2456638j,73386s,69998000n),-28800s,2299161j)> 
2.0.0-p195 :019 > a_date_time - b_date_time
 => (1727997655759/86400000000) 
2.0.0-p195 :020 > (a_date_time - b_date_time).to_i
 => 19 
2.0.0-p195 :021 > c_date_time = a_date_time-20
 => #<DateTime: 2013-12-11T12:23:03-08:00 ((2456638j,73383s,725757000n),-28800s,2299161j)> 
2.0.0-p195 :022 > a_date_time - c_date_time
 => (20/1) 
2.0.0-p195 :023 > (a_date_time - c_date_time).to_i
 => 20 

How to generate entire DDL of an Oracle schema (scriptable)?

The get_ddl procedure for a PACKAGE will return both spec AND body, so it will be better to change the query on the all_objects so the package bodies are not returned on the select.

So far I changed the query to this:

SELECT DBMS_METADATA.GET_DDL(REPLACE(object_type, ' ', '_'), object_name, owner)
FROM all_OBJECTS
WHERE (OWNER = 'OWNER1')
and object_type not like '%PARTITION'
and object_type not like '%BODY'
order by object_type, object_name;

Although other changes might be needed depending on the object types you are getting...

Specifying number of decimal places in Python

You don't show the code for display_data, but here's what you need to do:

print "$%0.02f" %amount

This is a format specifier for the variable amount.

Since this is beginner topic, I won't get into floating point rounding error, but it's good to be aware that it exists.

Check if an HTML input element is empty or has no value entered by user

You want:

if (document.getElementById('customx').value === ""){
    //do something
}

The value property will give you a string value and you need to compare that against an empty string.

Best HTML5 markup for sidebar

Update 17/07/27: As this is the most-voted answer, I should update this to include current information locally (with links to the references).

From the spec [1]:

The aside element represents a section of a page that consists of content that is tangentially related to the content of the parenting sectioning content, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.

Great! Exactly what we're looking for. In addition, it is best to check on <section> as well.

The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content. Each section should be identified, typically by including a heading (h1-h6 element) as a child of the section element.

...

A general rule is that the section element is appropriate only if the element’s contents would be listed explicitly in the document’s outline.

Excellent. Just what we're looking for. As opposed to <article> [2] which is for "self-contained" content, <section> allows for related content that isn't stand-alone, or generic enough for a <div> element.

As such, the spec seems to suggest that using Option 1, <aside> with <section> children is best practice.

References

  1. https://www.w3.org/TR/html51/sections.html#the-aside-element
  2. https://www.w3.org/TR/html51/sections.html#elementdef-article
  3. http://html5doctor.com/aside-revisited/

Difference between web server, web container and application server

The main difference between the web containers and application server is that most web containers such as Apache Tomcat implements only basic JSR like Servlet, JSP, JSTL wheres Application servers implements the entire Java EE Specification. Every application server contains web container.

Pipe output and capture exit status in Bash

This solution works without using bash specific features or temporary files. Bonus: in the end the exit status is actually an exit status and not some string in a file.

Situation:

someprog | filter

you want the exit status from someprog and the output from filter.

Here is my solution:

((((someprog; echo $? >&3) | filter >&4) 3>&1) | (read xs; exit $xs)) 4>&1

echo $?

See my answer for the same question on unix.stackexchange.com for a detailed explanation and an alternative without subshells and some caveats.

Display names of all constraints for a table in Oracle SQL

Use either of the two commands below. Everything must be in uppercase. The table name must be wrapped in quotation marks:

--SEE THE CONSTRAINTS ON A TABLE
SELECT COLUMN_NAME, CONSTRAINT_NAME FROM USER_CONS_COLUMNS WHERE TABLE_NAME = 'TBL_CUSTOMER';

--OR FOR LESS DETAIL
SELECT CONSTRAINT_NAME FROM USER_CONSTRAINTS WHERE TABLE_NAME = 'TBL_CUSTOMER';

Where is JAVA_HOME on macOS Mojave (10.14) to Lion (10.7)?

/usr/libexec/java_home is not a directory but an executable. It outputs the currently configured JAVA_HOME and doesn't actually change it. That's what the Java Preferences app is for, which in my case seems broken and doesn't actually change the JVM correctly. It does list the 1.7 JVM but I can toggle/untoggle & drag and drop all I want there without actually changing the output of /usr/libexec/java_home.

Even after installing 1.7.0 u6 from Oracle on Lion and setting it as the default in the preferences, it still returned the apple 1.6 java home. The only fix that actually works for me is setting JAVA_HOME manually:

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_06.jdk/Contents/Home/

At least this way when run from the command line it will use 1.7. /usr/libexec/java_home still insists on 1.6.

Update: Understanding Java From Command Line on OSX has a better explanation on how this works.

export JAVA_HOME=`/usr/libexec/java_home -v 1.7` 

is the way to do it. Note, updating this to 1.8 works just fine.

How can I display the current branch and folder path in terminal?

From Mac OS Catalina .bash_profile is replaced with .zprofile

Step 1: Create a .zprofile

touch .zprofile

Step 2:

nano .zprofile

type below line in this

source ~/.bash_profile

and save(ctrl+o return ctrl+x)

Step 3: Restart your terminal

To Add Git Branch Name Now you can add below lines in .bash_profile

    parse_git_branch() {
    git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'
}

export PS1="\u@\h \[\033[32m\]\w - \$(parse_git_branch)\[\033[00m\] $ "

Restart your terminal this will work.

Note: Even you can rename .bash_profile to .zprofile that also works.

How to make a window always stay on top in .Net?

I had a momentary 5 minute lapse and I forgot to specify the form in full like this:

  myformName.ActiveForm.TopMost = true;

But what I really wanted was THIS!

  this.TopMost = true;

MySQL - SELECT all columns WHERE one column is DISTINCT

What you want is the following:

SELECT DISTINCT * FROM posted WHERE ad='$key' GROUP BY link ORDER BY day, month

if there are 4 rows for example where link is the same, it will pick only one (I asume the first one).

What is the use of rt.jar file in java?

rt.jar contains all of the compiled class files for the base Java Runtime environment. You should not be messing with this jar file.

For MacOS it is called classes.jar and located under /System/Library/Frameworks/<java_version>/Classes . Same not messing with it rule applies there as well :).

http://javahowto.blogspot.com/2006/05/what-does-rtjar-stand-for-in.html

How do I pass JavaScript values to Scriptlet in JSP?

I've interpreted this question as:

"Can anyone tell me how to pass values for JavaScript for use in a JSP?"

If that's the case, this HTML file would pass a server-calculated variable to a JavaScript in a JSP.

<html>
    <body>
        <script type="text/javascript">
            var serverInfo = "<%=getServletContext().getServerInfo()%>";
            alert("Server information " + serverInfo);
        </script>
    </body>
</html>

How to mention C:\Program Files in batchfile

Now that bash is out for windows 10, if you want to access program files from bash, you can do it like so: cd /mnt/c/Program\ Files.

Apache HttpClient Interim Error: NoHttpResponseException

This can happen if disableContentCompression() is set on a pooling manager assigned to your HttpClient, and the target server is trying to use gzip compression.

use jQuery's find() on JSON object

The pure javascript solution is better, but a jQuery way would be to use the jQuery grep and/or map methods. Probably not much better than using $.each

jQuery.grep(TestObj, function(obj) {
    return obj.id === "A";
});

or

jQuery.map(TestObj, function(obj) {
    if(obj.id === "A")
         return obj; // or return obj.name, whatever.
});

Returns an array of the matching objects, or of the looked-up values in the case of map. Might be able to do what you want simply using those.

But in this example you'd have to do some recursion, because the data isn't a flat array, and we're accepting arbitrary structures, keys, and values, just like the pure javascript solutions do.

function getObjects(obj, key, val) {
    var retv = [];

    if(jQuery.isPlainObject(obj))
    {
        if(obj[key] === val) // may want to add obj.hasOwnProperty(key) here.
            retv.push(obj);

        var objects = jQuery.grep(obj, function(elem) {
            return (jQuery.isArray(elem) || jQuery.isPlainObject(elem));
        });

        retv.concat(jQuery.map(objects, function(elem){
            return getObjects(elem, key, val);
        }));
    }

    return retv;
}

Essentially the same as Box9's answer, but using the jQuery utility functions where useful.

········

Can an XSLT insert the current date?

XSLT 2

Date functions are available natively, such as:

<xsl:value-of  select="current-dateTime()"/>

There is also current-date() and current-time().

XSLT 1

Use the EXSLT date and times extension package.

  1. Download the date and times package from GitHub.
  2. Extract date.xsl to the location of your XSL files.
  3. Set the stylesheet header.
  4. Import date.xsl.

For example:

<xsl:stylesheet version="1.0" 
    xmlns:date="http://exslt.org/dates-and-times" 
    extension-element-prefixes="date"
    ...>

    <xsl:import href="date.xsl" />

    <xsl:template match="//root">
       <xsl:value-of select="date:date-time()"/>
    </xsl:template>
</xsl:stylesheet>

how to get yesterday's date in C#

You don't need to call DateTime.Today multiple times, just use it single time and format the date object in your desire format.. like that

 string result = DateTime.Now.Date.AddDays(-1).ToString("yyyy-MM-dd");

OR

 string result = DateTime.Today.AddDays(-1).ToString("yyyy-MM-dd");

Android - Handle "Enter" in an EditText

Hardware keyboards always yield enter events, but software keyboards return different actionIDs and nulls in singleLine EditTexts. This code responds every time the user presses enter in an EditText that this listener has been set to, regardless of EditText or keyboard type.

import android.view.inputmethod.EditorInfo;
import android.view.KeyEvent;
import android.widget.TextView.OnEditorActionListener;

listener=new TextView.OnEditorActionListener() {
  @Override
  public boolean onEditorAction(TextView view, int actionId, KeyEvent event) {
    if (event==null) {
      if (actionId==EditorInfo.IME_ACTION_DONE);
      // Capture soft enters in a singleLine EditText that is the last EditText.
      else if (actionId==EditorInfo.IME_ACTION_NEXT);
      // Capture soft enters in other singleLine EditTexts
      else return false;  // Let system handle all other null KeyEvents
    }
    else if (actionId==EditorInfo.IME_NULL) { 
    // Capture most soft enters in multi-line EditTexts and all hard enters.
    // They supply a zero actionId and a valid KeyEvent rather than
    // a non-zero actionId and a null event like the previous cases.
      if (event.getAction()==KeyEvent.ACTION_DOWN); 
      // We capture the event when key is first pressed.
      else  return true;   // We consume the event when the key is released.  
    }
    else  return false; 
    // We let the system handle it when the listener
    // is triggered by something that wasn't an enter.


    // Code from this point on will execute whenever the user
    // presses enter in an attached view, regardless of position, 
    // keyboard, or singleLine status.

    if (view==multiLineEditText)  multiLineEditText.setText("You pressed enter");
    if (view==singleLineEditText)  singleLineEditText.setText("You pressed next");
    if (view==lastSingleLineEditText)  lastSingleLineEditText.setText("You pressed done");
    return true;   // Consume the event
  }
};

The default appearance of the enter key in singleLine=false gives a bent arrow enter keypad. When singleLine=true in the last EditText the key says DONE, and on the EditTexts before it it says NEXT. By default, this behavior is consistent across all vanilla, android, and google emulators. The scrollHorizontal attribute doesn't make any difference. The null test is important because the response of phones to soft enters is left to the manufacturer and even in the emulators, the vanilla Level 16 emulators respond to long soft enters in multi-line and scrollHorizontal EditTexts with an actionId of NEXT and a null for the event.

In CSS how do you change font size of h1 and h2

 h1 { font-size: 150%; }
 h2 { font-size: 120%; }

Tune as needed.

Does hosts file exist on the iPhone? How to change it?

I just edited my iPhone's 'hosts' file successfully (on Jailbroken iOS 4.0).

  • Installed OpenSSH onto iPhone via Cydia
  • Using a SFTP client like FileZilla on my computer, I connected to my iPhone
    • Address: [use your phone's IP address or hostname, eg. simophone.local]
    • Username: root
    • Password: alpine
  • Located the /etc/hosts file
  • Made a backup on my computer (in case I want to revert my changes later)
  • Edited the hosts file in a decent text editor (such as Notepad++). See here for an explanation of the hosts file.
  • Uploaded the changes, overwriting the hosts file on the iPhone

The phone does cache some webpages and DNS queries, so a reboot or clearing the cache may help. Hope that helps someone.

Simon.

how do I change text in a label with swift?

Swift uses the same cocoa-touch API. You can call all the same methods, but they will use Swift's syntax. In this example you can do something like this:

self.simpleLabel.text = "message"

Note the setText method isn't available. Setting the label's text with = will automatically call the setter in swift.

Stacked Bar Plot in R

I'm obviosly not a very good R coder, but if you wanted to do this with ggplot2:

data<- rbind(c(480, 780, 431, 295, 670, 360,  190),
             c(720, 350, 377, 255, 340, 615,  345),
             c(460, 480, 179, 560,  60, 735, 1260),
             c(220, 240, 876, 789, 820, 100,   75))

a <- cbind(data[, 1], 1, c(1:4))
b <- cbind(data[, 2], 2, c(1:4))
c <- cbind(data[, 3], 3, c(1:4))
d <- cbind(data[, 4], 4, c(1:4))
e <- cbind(data[, 5], 5, c(1:4))
f <- cbind(data[, 6], 6, c(1:4))
g <- cbind(data[, 7], 7, c(1:4))

data           <- as.data.frame(rbind(a, b, c, d, e, f, g))
colnames(data) <-c("Time", "Type", "Group")
data$Type      <- factor(data$Type, labels = c("A", "B", "C", "D", "E", "F", "G"))

library(ggplot2)

ggplot(data = data, aes(x = Type, y = Time, fill = Group)) + 
       geom_bar(stat = "identity") +
       opts(legend.position = "none")

enter image description here

Rename a table in MySQL

The mysql query for rename table is

Rename Table old_name TO new_name

In your query, you've used group which one of the keywords in MySQL. Try to avoid mysql keywords for name while creating table, field name and so on.

What is a clean, Pythonic way to have multiple constructors in Python?

One should definitely prefer the solutions already posted, but since no one mentioned this solution yet, I think it is worth mentioning for completeness.

The @classmethod approach can be modified to provide an alternative constructor which does not invoke the default constructor (__init__). Instead, an instance is created using __new__.

This could be used if the type of initialization cannot be selected based on the type of the constructor argument, and the constructors do not share code.

Example:

class MyClass(set):

    def __init__(self, filename):
        self._value = load_from_file(filename)

    @classmethod
    def from_somewhere(cls, somename):
        obj = cls.__new__(cls)  # Does not call __init__
        super(MyClass, obj).__init__()  # Don't forget to call any polymorphic base class initializers
        obj._value = load_from_somewhere(somename)
        return obj

How to preserve insertion order in HashMap?

LinkedHashMap is precisely what you're looking for.

It is exactly like HashMap, except that when you iterate over it, it presents the items in the insertion order.

Jquery $.ajax fails in IE on cross domain calls

I had a similar problem in IE9 where some CORS calls were aborting, while others weren't. My app is also dependent on a promise interface, so the XDomainRequest suggestions above weren't EXACTLY what I needed, so I added a deferred into my service.get workaround for IE9. Hopefully it can be useful to someone else running across this problem. :

    get: function (url) {
        if ('XDomainRequest' in window && window.XDomainRequest !== null) {
            var deferred = $.Deferred();
            var xdr      = new XDomainRequest();

            xdr.open("get", url);

            xdr.onload = function() {
              json = xdr.responseText;
              parsed_json = $.parseJSON(json);
              deferred.resolve(parsed_json);
            }

            xdr.send();
            return deferred;
        } else {
            return $.ajax({
                url: url,
                type: 'GET',
                dataType: 'json',
                crossDomain: true
            });
        }
    }

How to check if a variable is both null and /or undefined in JavaScript

A variable cannot be both null and undefined at the same time. However, the direct answer to your question is:

if (variable != null)

One =, not two.

There are two special clauses in the "abstract equality comparison algorithm" in the JavaScript spec devoted to the case of one operand being null and the other being undefined, and the result is true for == and false for !=. Thus if the value of the variable is undefined, it's not != null, and if it's not null, it's obviously not != null.

Now, the case of an identifier not being defined at all, either as a var or let, as a function parameter, or as a property of the global context is different. A reference to such an identifier is treated as an error at runtime. You could attempt a reference and catch the error:

var isDefined = false;
try {
  (variable);
  isDefined = true;
}
catch (x) {}

I would personally consider that a questionable practice however. For global symbols that may or may be there based on the presence or absence of some other library, or some similar situation, you can test for a window property (in browser JavaScript):

var isJqueryAvailable = window.jQuery != null;

or

var isJqueryAvailable = "jQuery" in window;

How to prevent errno 32 broken pipe?

It depends on how you tested it, and possibly on differences in the TCP stack implementation of the personal computer and the server.

For example, if your sendall always completes immediately (or very quickly) on the personal computer, the connection may simply never have broken during sending. This is very likely if your browser is running on the same machine (since there is no real network latency).


In general, you just need to handle the case where a client disconnects before you're finished, by handling the exception.

Remember that TCP communications are asynchronous, but this is much more obvious on physically remote connections than on local ones, so conditions like this can be hard to reproduce on a local workstation. Specifically, loopback connections on a single machine are often almost synchronous.

Apache could not be started - ServerRoot must be a valid directory and Unable to find the specified module

Below solved. I have wrongly given the bin /directory/, so faced the issue:

if you installed apache at C:/httpd-2.4.41-o102s-x64-vc14-r2/Apache24
then the modules are at.. C:/httpd-2.4.41-o102s-x64-vc14-r2/Apache24/modules

So, the file           C:/httpd-2.4.41-o102s-x64-vc14-r2/Apache24/conf/httpd.conf
should have
       Define SRVROOT "C:/httpd-2.4.41-o102s-x64-vc14-r2/Apache24/"

Hope that helps

SQL Server: Importing database from .mdf?

See: How to: Attach a Database File to SQL Server Express

Login to the database via sqlcmd:

sqlcmd -S Server\Instance

And then issue the commands:

USE [master]
GO
CREATE DATABASE [database_name] ON 
( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Data\<database name>.mdf' ),
( FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Data\<database name>.ldf' )
 FOR ATTACH ;
GO

What does it mean to "call" a function in Python?

To "call" means to make a reference in your code to a function that is written elsewhere. This function "call" can be made to the standard Python library (stuff that comes installed with Python), third-party libraries (stuff other people wrote that you want to use), or your own code (stuff you wrote). For example:

#!/usr/env python

import os

def foo():
    return "hello world"

print os.getlogin()
print foo()

I created a function called "foo" and called it later on with that print statement. I imported the standard "os" Python library then I called the "getlogin" function within that library.

How to get an input text value in JavaScript

<input type="password"id="har">
<input type="submit"value="get password"onclick="har()">
<script>
    function har() {
        var txt_val;
        txt_val = document.getElementById("har").value;
        alert(txt_val);
    }
</script>

How to control the width of select tag?

USE style="max-width:90%;"

<select name=countries  style="max-width:90%;">
 <option value=af>Afghanistan</option>
 <option value=ax>Åland Islands</option>
 ...
 <option value=gs>South Georgia and the South Sandwich Islands</option>
 ...
</select>  

LIVE DEMO

Targeting only Firefox with CSS

Now that Firefox Quantum 57 is out with substantial — and potentially breaking — improvements to Gecko collectively known as Stylo or Quantum CSS, you may find yourself in a situation where you have to distinguish between legacy versions of Firefox and Firefox Quantum.

From my answer here:

You can use @supports with a calc(0s) expression in conjunction with @-moz-document to test for Stylo — Gecko does not support time values in calc() expressions but Stylo does:

@-moz-document url-prefix() {
  @supports (animation: calc(0s)) {
    /* Stylo */
  }
}

Here's a proof-of-concept:

_x000D_
_x000D_
body::before {_x000D_
  content: 'Not Fx';_x000D_
}_x000D_
_x000D_
@-moz-document url-prefix() {_x000D_
  body::before {_x000D_
    content: 'Fx legacy';_x000D_
  }_x000D_
_x000D_
  @supports (animation: calc(0s)) {_x000D_
    body::before {_x000D_
      content: 'Fx Quantum';_x000D_
    }_x000D_
  }_x000D_
}
_x000D_
_x000D_
_x000D_

Targeting legacy versions of Firefox is a little tricky — if you're only interested in versions that support @supports, which is Fx 22 and up, @supports not (animation: calc(0s)) is all you need:

@-moz-document url-prefix() {
  @supports not (animation: calc(0s)) {
    /* Gecko */
  }
}

... but if you need to support even older versions, you'll need to make use of the cascade, as demonstrated in the proof-of-concept above.

What is the shortcut in IntelliJ IDEA to find method / functions?

Windows : ctrl + F12

MacOS : cmd + F12

Above commands will show the functions/methods in the current class.

Press SHIFT TWO times if you want to search both class and method in the whole project.

Resolve Javascript Promise outside function scope

I've put together a gist that does that job: https://gist.github.com/thiagoh/c24310b562d50a14f3e7602a82b4ef13

here's how you should use it:

import ExternalizedPromiseCreator from '../externalized-promise';

describe('ExternalizedPromise', () => {
  let fn: jest.Mock;
  let deferredFn: jest.Mock;
  let neverCalledFn: jest.Mock;
  beforeEach(() => {
    fn = jest.fn();
    deferredFn = jest.fn();
    neverCalledFn = jest.fn();
  });

  it('resolve should resolve the promise', done => {
    const externalizedPromise = ExternalizedPromiseCreator.create(() => fn());

    externalizedPromise
      .promise
      .then(() => deferredFn())
      .catch(() => neverCalledFn())
      .then(() => {
        expect(deferredFn).toHaveBeenCalled();
        expect(neverCalledFn).not.toHaveBeenCalled();
        done();
      });

    expect(fn).toHaveBeenCalled();
    expect(neverCalledFn).not.toHaveBeenCalled();
    expect(deferredFn).not.toHaveBeenCalled();

    externalizedPromise.resolve();
  });
  ...
});

Pandas/Python: Set value of one column based on value in another column

one way to do this would be to use indexing with .loc.

Example

In the absence of an example dataframe, I'll make one up here:

import numpy as np
import pandas as pd

df = pd.DataFrame({'c1': list('abcdefg')})
df.loc[5, 'c1'] = 'Value'

>>> df
      c1
0      a
1      b
2      c
3      d
4      e
5  Value
6      g

Assuming you wanted to create a new column c2, equivalent to c1 except where c1 is Value, in which case, you would like to assign it to 10:

First, you could create a new column c2, and set it to equivalent as c1, using one of the following two lines (they essentially do the same thing):

df = df.assign(c2 = df['c1'])
# OR:
df['c2'] = df['c1']

Then, find all the indices where c1 is equal to 'Value' using .loc, and assign your desired value in c2 at those indices:

df.loc[df['c1'] == 'Value', 'c2'] = 10

And you end up with this:

>>> df
      c1  c2
0      a   a
1      b   b
2      c   c
3      d   d
4      e   e
5  Value  10
6      g   g

If, as you suggested in your question, you would perhaps sometimes just want to replace the values in the column you already have, rather than create a new column, then just skip the column creation, and do the following:

df['c1'].loc[df['c1'] == 'Value'] = 10
# or:
df.loc[df['c1'] == 'Value', 'c1'] = 10

Giving you:

>>> df
      c1
0      a
1      b
2      c
3      d
4      e
5     10
6      g

Convert command line argument to string

It's already an array of C-style strings:

#include <iostream>
#include <string>
#include <vector>


int main(int argc, char *argv[]) // Don't forget first integral argument 'argc'
{
  std::string current_exec_name = argv[0]; // Name of the current exec program
  std::vector<std::string> all_args;

  if (argc > 1) {
    all_args.assign(argv + 1, argv + argc);
  }
}

Argument argc is count of arguments plus the current exec file.

Setting user agent of a java URLConnection

Just for clarification: setRequestProperty("User-Agent", "Mozilla ...") now works just fine and doesn't append java/xx at the end! At least with Java 1.6.30 and newer.

I listened on my machine with netcat(a port listener):

$ nc -l -p 8080

It simply listens on the port, so you see anything which gets requested, like raw http-headers.

And got the following http-headers without setRequestProperty:

GET /foobar HTTP/1.1
User-Agent: Java/1.6.0_30
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

And WITH setRequestProperty:

GET /foobar HTTP/1.1
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2
Host: localhost:8080
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

As you can see the user agent was properly set.

Full example:

import java.io.IOException;
import java.net.URL;
import java.net.URLConnection;


public class TestUrlOpener {

    public static void main(String[] args) throws IOException {
        URL url = new URL("http://localhost:8080/foobar");
        URLConnection hc = url.openConnection();
        hc.setRequestProperty("User-Agent", "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.4; en-US; rv:1.9.2.2) Gecko/20100316 Firefox/3.6.2");

        System.out.println(hc.getContentType());
    }

}

How to position a div in the middle of the screen when the page is bigger than the screen

Try this one.

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

how to stop a for loop

In order to jump out of a loop, you need to use the break statement.

n=L[0][0]
m=len(A)
for i in range(m):
 for j in range(m):
   if L[i][j]!=n:
       break;

Here you have the official Python manual with the explanation about break and continue, and other flow control statements:

http://docs.python.org/tutorial/controlflow.html

EDITED: As a commenter pointed out, this does only end the inner loop. If you need to terminate both loops, there is no "easy" way (others have given you a few solutions). One possiblity would be to raise an exception:

def f(L, A):
    try:
        n=L[0][0]
        m=len(A)
        for i in range(m):
             for j in range(m):
                 if L[i][j]!=n:
                     raise RuntimeError( "Not equal" )
        return True
    except:
        return False