Programs & Examples On #Function object

What are C++ functors and their uses?

Here's an actual situation where I was forced to use a Functor to solve my problem:

I have a set of functions (say, 20 of them), and they are all identical, except each calls a different specific function in 3 specific spots.

This is incredible waste, and code duplication. Normally I would just pass in a function pointer, and just call that in the 3 spots. (So the code only needs to appear once, instead of twenty times.)

But then I realized, in each case, the specific function required a completely different parameter profile! Sometimes 2 parameters, sometimes 5 parameters, etc.

Another solution would be to have a base class, where the specific function is an overridden method in a derived class. But do I really want to build all of this INHERITANCE, just so I can pass a function pointer????

SOLUTION: So what I did was, I made a wrapper class (a "Functor") which is able to call any of the functions I needed called. I set it up in advance (with its parameters, etc) and then I pass it in instead of a function pointer. Now the called code can trigger the Functor, without knowing what is happening on the inside. It can even call it multiple times (I needed it to call 3 times.)


That's it -- a practical example where a Functor turned out to be the obvious and easy solution, which allowed me to reduce code duplication from 20 functions to 1.

How to use CMAKE_INSTALL_PREFIX

There are two ways to use this variable:

  • passing it as a command line argument just like Job mentioned:

    cmake -DCMAKE_INSTALL_PREFIX=< install_path > ..

  • assigning value to it in CMakeLists.txt:

    SET(CMAKE_INSTALL_PREFIX < install_path >)

    But do remember to place it BEFORE PROJECT(< project_name>) command, otherwise it will not work!

Python open() gives FileNotFoundError/IOError: Errno 2 No such file or directory

If is VSCode see the workspace. If you are in other workspace this error can rise

grep regex whitespace behavior

This looks like a behavior difference in the handling of \s between grep 2.5 and newer versions (a bug in old grep?). I confirm your result with grep 2.5.4, but all four of your greps do work when using grep 2.6.3 (Ubuntu 10.10).

Note:

GNU grep 2.5.4
echo "foo bar" | grep "\s"
   (doesn't match)

whereas

GNU grep 2.6.3
echo "foo bar" | grep "\s"
foo bar

Probably less trouble (as \s is not documented):

Both GNU greps
echo "foo bar" | grep "[[:space:]]"
foo bar

My advice is to avoid using \s ... use [ \t]* or [[:space:]] or something like it instead.

GitLab git user password

It prompted me for password.

It shouldn't.
If you have the right public/private key representing a user authorized to access project-x, then gitlab won't ask you for anything.

But that supposes that ssh -vT [email protected] is working first.

Get class list for element with jQuery

Here you go, just tweaked readsquare's answer to return an array of all classes:

function classList(elem){
   var classList = elem.attr('class').split(/\s+/);
    var classes = new Array(classList.length);
    $.each( classList, function(index, item){
        classes[index] = item;
    });

    return classes;
}

Pass a jQuery element to the function, so that a sample call will be:

var myClasses = classList($('#myElement'));

Validating IPv4 addresses with regexp

mysql> select ip from foo where ip regexp '^\\s*[0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]\\s*';

Why does dividing two int not yield the right value when assigned to double?

This is because you are using the integer division version of operator/, which takes 2 ints and returns an int. In order to use the double version, which returns a double, at least one of the ints must be explicitly casted to a double.

c = a/(double)b;

Uri content://media/external/file doesn't exist for some devices

Most probably it has to do with caching on the device. Catching the exception and ignoring is not nice but my problem was fixed and it seems to work.

Internal and external fragmentation

External fragmentation
Total memory space is enough to satisfy a request or to reside a process in it, but it is not contiguous so it can not be used.

External fragmentation

Internal fragmentation
Memory block assigned to process is bigger. Some portion of memory is left unused as it can not be used by another process.

Internal fragmentation

How to sort findAll Doctrine's method?

Modify the default findAll function in EntityRepository like this:

public function findAll( array $orderBy = null )
{
    return $this->findBy([], $orderBy);
}

That way you can use the ''findAll'' on any query for any data table with an option to sort the query

Jquery in React is not defined

It happens mostly when JQuery is not installed in your project. Install JQuery in your project by following commands according to your package manager.

Yarn

yarn add jquery

npm

npm i jquery --save

After this just import $ in your project file. import $ from 'jquery'

jQuery issue in Internet Explorer 8

I had this problem and tried the solutions mentioned here with no success.

Eventually, I realised that I was linking to the Google CDN version of the script using an http URL while the page embedding the script was an https page.

This caused IE to not load jquery (it prompts the user whether they want to load only secure content). Changing the Google CDN URL to use the https scheme fixed the problem for me.

How can I format a decimal to always show 2 decimal places?

The Easiest way example to show you how to do that is :

Code :

>>> points = 19.5 >>> total = 22 >>>'Correct answers: {:.2%}'.format(points/total) `

Output : Correct answers: 88.64%

How to fix "no valid 'aps-environment' entitlement string found for application" in Xcode 4.3?

First of all, you don't need the entitlements file unless you are adding custom key/value pairs that do not exist in the provisioning profile. When your app is built, any entitlements from the provisioning profile will be copied to the app.

Given that you still see an error message about missing entitlements, I can only assume the code signing options are not correct in the build settings.

You need to make sure the correct profile is selected for the "Debug" configuration, and to be safe, that you have selected the correct profile for both the "Debug" and child-node labelled "Any iOS SDK":

enter image description here

Although this screenshot shows the "Automatic Developer" profile selected, choose the exact provisioning profile you want from the drop down, just for testing purposes. It could be that Xcode is automatically choosing a different profile than the one you want.

Also be sure to do a clean build, completely delete the app from your device, etc. This is just to make sure you don't have some old fluff hanging around.

How do I time a method's execution in Java?

This probably isn't what you wanted me to say, but this is a good use of AOP. Whip an proxy interceptor around your method, and do the timing in there.

The what, why and how of AOP is rather beyond the scope of this answer, sadly, but that's how I'd likely do it.

Edit: Here's a link to Spring AOP to get you started, if you're keen. This is the most accessible implementation of AOP that Iive come across for java.

Also, given everyone else's very simple suggestions, I should add that AOP is for when you don't want stuff like timing to invade your code. But in many cases, that sort of simple and easy approach is fine.

How to playback MKV video in web browser?

To use video extensions that are MKV. You should use video, not source

For example :

_x000D_
_x000D_
  <!-- mkv -->
  <video width="320" height="240" controls src="assets/animation.mkv"></video>
<!-- mp4 -->
  <video width="320" height="240" controls>
    <source src="assets/animation.mp4" type="video/mp4" />
  </video>
_x000D_
_x000D_
_x000D_ My answer may be incomprehensible to you, so if you do not understand, click on this

rsync error: failed to set times on "/foo/bar": Operation not permitted

It could be that you don't have privileges to some of the files. From an administrator account, try "sudo rsync -av " Alternately, enable the root account and sign in as root. That should allow you to completely hose your system and brute force your rsync! ;-) I'm not sure if the above mentioned --extended-attributes will help, but I threw it in too, just for good measure.

Test if executable exists in Python?

This seems simple enough and works both in python 2 and 3

try: subprocess.check_output('which executable',shell=True)
except: sys.exit('ERROR: executable not found')

Pass multiple arguments into std::thread

If you're getting this, you may have forgotten to put #include <thread> at the beginning of your file. OP's signature seems like it should work.

Git vs Team Foundation Server

For me the major difference is all the ancilliary files that TFS will add to your solution (.vssscc) to 'support' TFS - we've had recent issues with these files ending up mapped to the wrong branch, which lead to some interesting debugging...

Redis command to get all available keys?

redis-cli -h <host> -p <port> keys * 

where * is the pattern to list all keys

Service Temporarily Unavailable Magento?

Simply delete the maintenance.flag file in root folder and then delete the files of cache folder and session folder inside var/ folder.

Group By Multiple Columns

Though this question is asking about group by class properties, if you want to group by multiple columns against a ADO object (like a DataTable), you have to assign your "new" items to variables:

EnumerableRowCollection<DataRow> ClientProfiles = CurrentProfiles.AsEnumerable()
                        .Where(x => CheckProfileTypes.Contains(x.Field<object>(ProfileTypeField).ToString()));
// do other stuff, then check for dups...
                    var Dups = ClientProfiles.AsParallel()
                        .GroupBy(x => new { InterfaceID = x.Field<object>(InterfaceField).ToString(), ProfileType = x.Field<object>(ProfileTypeField).ToString() })
                        .Where(z => z.Count() > 1)
                        .Select(z => z);

How to rename HTML "browse" button of an input type=file?

The button isn't called the "browse button" — that's just the name your browser gives for it. Browsers are free to implement the file upload control however they like. In Safari, for example, it's called "Choose File" and it's on the opposite side of whatever you're probably using.

You can implement a custom look for the upload control using the technique outlined on QuirksMode, but that goes beyond just changing the button's text.

How to fix "Incorrect string value" errors?

Hi i also got this error when i use my online databases from godaddy server i think it has the mysql version of 5.1 or more. but when i do from my localhost server (version 5.7) it was fine after that i created the table from local server and copied to the online server using mysql yog i think the problem is with character set

Screenshot Here

Storing SHA1 hash values in MySQL

I would use VARCHAR for variable length data, but not with fixed length data. Because a SHA-1 value is always 160 bit long, the VARCHAR would just waste an additional byte for the length of the fixed-length field.

And I also wouldn’t store the value the SHA1 is returning. Because it uses just 4 bit per character and thus would need 160/4 = 40 characters. But if you use 8 bit per character, you would only need a 160/8 = 20 character long field.

So I recommend you to use BINARY(20) and the UNHEX function to convert the SHA1 value to binary.

I compared storage requirements for BINARY(20) and CHAR(40).

CREATE TABLE `binary` (
    `id` int unsigned auto_increment primary key,
    `password` binary(20) not null
);
CREATE TABLE `char` (
    `id` int unsigned auto_increment primary key,
    `password` char(40) not null
);

With million of records binary(20) takes 44.56M, while char(40) takes 64.57M. InnoDB engine.

Adding extra zeros in front of a number using jQuery?

I have a potential solution which I guess is relevent, I posted about it here:

https://www.facebook.com/antimatterstudios/posts/10150752380719364

basically, you want a minimum length of 2 or 3, you can adjust how many 0's you put in this piece of code

var d = new Date();
var h = ("0"+d.getHours()).slice(-2);
var m = ("0"+d.getMinutes()).slice(-2);
var s = ("0"+d.getSeconds()).slice(-2);

I knew I would always get a single integer as a minimum (cause hour 1, hour 2) etc, but if you can't be sure of getting anything but an empty string, you can just do "000"+d.getHours() to make sure you get the minimum.

then you want 3 numbers? just use -3 instead of -2 in my code, I'm just writing this because I wanted to construct a 24 hour clock in a super easy fashion.

Difference between Grunt, NPM and Bower ( package.json vs bower.json )

Npm and Bower are both dependency management tools. But the main difference between both is npm is used for installing Node js modules but bower js is used for managing front end components like html, css, js etc.

A fact that makes this more confusing is that npm provides some packages which can be used in front-end development as well, like grunt and jshint.

These lines add more meaning

Bower, unlike npm, can have multiple files (e.g. .js, .css, .html, .png, .ttf) which are considered the main file(s). Bower semantically considers these main files, when packaged together, a component.

Edit: Grunt is quite different from Npm and Bower. Grunt is a javascript task runner tool. You can do a lot of things using grunt which you had to do manually otherwise. Highlighting some of the uses of Grunt:

  1. Zipping some files (e.g. zipup plugin)
  2. Linting on js files (jshint)
  3. Compiling less files (grunt-contrib-less)

There are grunt plugins for sass compilation, uglifying your javascript, copy files/folders, minifying javascript etc.

Please Note that grunt plugin is also an npm package.

Question-1

When I want to add a package (and check in the dependency into git), where does it belong - into package.json or into bower.json

It really depends where does this package belong to. If it is a node module(like grunt,request) then it will go in package.json otherwise into bower json.

Question-2

When should I ever install packages explicitly like that without adding them to the file that manages dependencies

It does not matter whether you are installing packages explicitly or mentioning the dependency in .json file. Suppose you are in the middle of working on a node project and you need another project, say request, then you have two options:

  • Edit the package.json file and add a dependency on 'request'
  • npm install

OR

  • Use commandline: npm install --save request

--save options adds the dependency to package.json file as well. If you don't specify --save option, it will only download the package but the json file will be unaffected.

You can do this either way, there will not be a substantial difference.

Calculate summary statistics of columns in dataframe

describe may give you everything you want otherwise you can perform aggregations using groupby and pass a list of agg functions: http://pandas.pydata.org/pandas-docs/stable/groupby.html#applying-multiple-functions-at-once

In [43]:

df.describe()

Out[43]:

       shopper_num is_martian  number_of_items  count_pineapples
count      14.0000         14        14.000000                14
mean        7.5000          0         3.357143                 0
std         4.1833          0         6.452276                 0
min         1.0000      False         0.000000                 0
25%         4.2500          0         0.000000                 0
50%         7.5000          0         0.000000                 0
75%        10.7500          0         3.500000                 0
max        14.0000      False        22.000000                 0

[8 rows x 4 columns]

Note that some columns cannot be summarised as there is no logical way to summarise them, for instance columns containing string data

As you prefer you can transpose the result if you prefer:

In [47]:

df.describe().transpose()

Out[47]:

                 count      mean       std    min   25%  50%    75%    max
shopper_num         14       7.5    4.1833      1  4.25  7.5  10.75     14
is_martian          14         0         0  False     0    0      0  False
number_of_items     14  3.357143  6.452276      0     0    0    3.5     22
count_pineapples    14         0         0      0     0    0      0      0

[4 rows x 8 columns]

disabling spring security in spring boot app

I think you must also remove security auto config from your @SpringBootApplication annotated class:

@EnableAutoConfiguration(exclude = {
    org.springframework.boot.autoconfigure.security.SecurityAutoConfiguration.class,
    org.springframework.boot.actuate.autoconfigure.ManagementSecurityAutoConfiguration.class})

DateTime vs DateTimeOffset

The most important distinction is that DateTime does not store time zone information, while DateTimeOffset does.

Although DateTime distinguishes between UTC and Local, there is absolutely no explicit time zone offset associated with it. If you do any kind of serialization or conversion, the server's time zone is going to be used. Even if you manually create a local time by adding minutes to offset a UTC time, you can still get bit in the serialization step, because (due to lack of any explicit offset in DateTime) it will use the server's time zone offset.

For example, if you serialize a DateTime value with Kind=Local using Json.Net and an ISO date format, you'll get a string like 2015-08-05T07:00:00-04. Notice that last part (-04) had nothing to do with your DateTime or any offset you used to calculate it... it's just purely the server's time zone offset.

Meanwhile, DateTimeOffset explicitly includes the offset. It may not include the name of the time zone, but at least it includes the offset, and if you serialize it, you're going to get the explicitly included offset in your value instead of whatever the server's local time happens to be.

Resolving LNK4098: defaultlib 'MSVCRT' conflicts with

IMO this link from Yochai Timmer was very good and relevant but painful to read. I wrote a summary.

Yochai, if you ever read this, please see the note at the end.


For the original post read : warning LNK4098: defaultlib "LIBCD" conflicts with use of other libs

Error

LINK : warning LNK4098: defaultlib "LIBCD" conflicts with use of other libs; use /NODEFAULTLIB:library

Meaning

one part of the system was compiled to use a single threaded standard (libc) library with debug information (libcd) which is statically linked

while another part of the system was compiled to use a multi-threaded standard library without debug information which resides in a DLL and uses dynamic linking

How to resolve

  • Ignore the warning, after all it is only a warning. However, your program now contains multiple instances of the same functions.

  • Use the linker option /NODEFAULTLIB:lib. This is not a complete solution, even if you can get your program to link this way you are ignoring a warning sign: the code has been compiled for different environments, some of your code may be compiled for a single threaded model while other code is multi-threaded.

  • [...] trawl through all your libraries and ensure they have the correct link settings

In the latter, as it in mentioned in the original post, two common problems can arise :

  • You have a third party library which is linked differently to your application.

  • You have other directives embedded in your code: normally this is the MFC. If any modules in your system link against MFC all your modules must nominally link against the same version of MFC.

For those cases, ensure you understand the problem and decide among the solutions.


Note : I wanted to include that summary of Yochai Timmer's link into his own answer but since some people have trouble to review edits properly I had to write it in a separate answer. Sorry

Java properties UTF-8 encoding in Eclipse

This seems to work only for some characters ... including special characters for German, Portuguese, French. However, I ran into trouble with Russian, Hindi and Mandarin characters. These are not converted to Properties format 'native2ascii', instead get saved with ?? ?? ??
The only way I could get my app to display these characters correctly is by putting them in the properties file translated to UTF-8 format - as \u0915 instead of ?, or \u044F instead of ?. Any advice?

PHP: How to send HTTP response code?

If you are here because of Wordpress giving 404's when loading the environment, this should fix the problem:

define('WP_USE_THEMES', false);
require('../wp-blog-header.php');
status_header( 200 );
//$wp_query->is_404=false; // if necessary

The problem is due to it sending a Status: 404 Not Found header. You have to override that. This will also work:

define('WP_USE_THEMES', false);
require('../wp-blog-header.php');
header("HTTP/1.1 200 OK");
header("Status: 200 All rosy");

Add column to SQL query results

why dont you add a "source" column to each of the queries with a static value like

select 'source 1' as Source, column1, column2...
from table1

UNION ALL

select 'source 2' as Source, column1, column2...
from table2

Vue.js unknown custom element

I was following along the Vue documentation at https://vuejs.org/v2/guide/index.html when I ran into this issue.

Later they clarify the syntax:

So far, we’ve only registered components globally, using Vue.component:

   Vue.component('my-component-name', {
       // ... options ...
   })

Globally registered components can be used in the template of any root Vue instance (new Vue) created afterwards – and even inside all >subcomponents of that Vue instance’s component tree.

(https://vuejs.org/v2/guide/components.html#Organizing-Components)

So as Umesh Kadam says above, just make sure the global component definition comes before the var app = new Vue({}) instantiation.

Print current call stack from a method in Python code

Here's an example of getting the stack via the traceback module, and printing it:

import traceback

def f():
    g()

def g():
    for line in traceback.format_stack():
        print(line.strip())

f()

# Prints:
# File "so-stack.py", line 10, in <module>
#     f()
# File "so-stack.py", line 4, in f
#     g()
# File "so-stack.py", line 7, in g
#     for line in traceback.format_stack():

If you really only want to print the stack to stderr, you can use:

traceback.print_stack()

Or to print to stdout (useful if want to keep redirected output together), use:

traceback.print_stack(file=sys.stdout)

But getting it via traceback.format_stack() lets you do whatever you like with it.

In HTML5, should the main navigation be inside or outside the <header> element?

It's a little unclear whether you're asking for opinions, eg. "it's common to do xxx" or an actual rule, so I'm going to lean in the direction of rules.

The examples you cite seem based upon the examples in the spec for the nav element. Remember that the spec keeps getting tweaked and the rules are sometimes convoluted, so I'd venture many people might tend to just do what's given rather than interpret. You're showing two separate examples with different behavior, so there's only so much you can read into it. Do either of those sites also have the opposing sub/nav situation, and if so how do they handle it?

Most importantly, though, there's nothing in the spec saying either is the way to do it. One of the goals with HTML5 was to be very clear[this for comparison] about semantics, requirements, etc. so the omission is worth noting. As far as I can see, the examples are independent of each other and equally valid within their own context of layout requirements, etc.

Having the nav's source position be conditional is kind of silly(another red flag). Just pick a method and go with it.

How to list the properties of a JavaScript object?

In modern browsers (IE9+, FF4+, Chrome5+, Opera12+, Safari5+) you can use the built in Object.keys method:

var keys = Object.keys(myObject);

The above has a full polyfill but a simplified version is:

var getKeys = function(obj){
   var keys = [];
   for(var key in obj){
      keys.push(key);
   }
   return keys;
}

Alternatively replace var getKeys with Object.prototype.keys to allow you to call .keys() on any object. Extending the prototype has some side effects and I wouldn't recommend doing it.

Defining and using a variable in batch file

Consider also using SETX - it will set variable on user or machine (available for all users) level though the variable will be usable with the next opening of the cmd.exe ,so often it can be used together with SET :

::setting variable for the current user
if not defined My_Var (
  set "My_Var=My_Value"
  setx My_Var My_Value
)

::setting machine defined variable
if not defined Global_Var (
  set "Global_Var=Global_Value"
  SetX Global_Var Global_Value /m
)

You can also edit directly the registry values:

User Variables: HKEY_CURRENT_USER\Environment

System Variables: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment

Which will allow to avoid some restrictions of SET and SETX like the variables containing = in their names.

How to replace innerHTML of a div using jQuery?

If you instead have a jQuery object you want to render instead of the existing content: Then just reset the content and append the new.

var itemtoReplaceContentOf = $('#regTitle');
itemtoReplaceContentOf.html('');
newcontent.appendTo(itemtoReplaceContentOf);

Or:

$('#regTitle').empty().append(newcontent);

How to copy file from HDFS to the local file system

  1. bin/hadoop fs -get /hdfs/source/path /localfs/destination/path
  2. bin/hadoop fs -copyToLocal /hdfs/source/path /localfs/destination/path
  3. Point your web browser to HDFS WEBUI(namenode_machine:50070), browse to the file you intend to copy, scroll down the page and click on download the file.

Retrofit 2 - URL Query Parameter

If you specify @GET("foobar?a=5"), then any @Query("b") must be appended using &, producing something like foobar?a=5&b=7.

If you specify @GET("foobar"), then the first @Query must be appended using ?, producing something like foobar?b=7.

That's how Retrofit works.

When you specify @GET("foobar?"), Retrofit thinks you already gave some query parameter, and appends more query parameters using &.

Remove the ?, and you will get the desired result.

How to both read and write a file in C#

You need a single stream, opened for both reading and writing.

FileStream fileStream = new FileStream(
      @"c:\words.txt", FileMode.OpenOrCreate, 
      FileAccess.ReadWrite, FileShare.None);

How to split a number into individual digits in c#?

You can simply do:

"123456".Select(q => new string(q,1)).ToArray();

to have an enumerable of integers, as per comment request, you can:

"123456".Select(q => int.Parse(new string(q,1))).ToArray();

It is a little weak since it assumes the string actually contains numbers.

SQL How to remove duplicates within select query?

Select Distinct CAST(FLOOR( CAST(start_date AS FLOAT ) )AS DATETIME) from Table

How to get unique device hardware id in Android?

Update: 19 -11-2019

The below answer is no more relevant to present day.

So for any one looking for answers you should look at the documentation linked below

https://developer.android.com/training/articles/user-data-ids


Old Answer - Not relevant now. You check this blog in the link below

http://android-developers.blogspot.in/2011/03/identifying-app-installations.html

ANDROID_ID

import android.provider.Settings.Secure;

private String android_id = Secure.getString(getContext().getContentResolver(),
                                                    Secure.ANDROID_ID); 

The above is from the link @ Is there a unique Android device ID?

More specifically, Settings.Secure.ANDROID_ID. This is a 64-bit quantity that is generated and stored when the device first boots. It is reset when the device is wiped.

ANDROID_ID seems a good choice for a unique device identifier. There are downsides: First, it is not 100% reliable on releases of Android prior to 2.2 (“Froyo”). Also, there has been at least one widely-observed bug in a popular handset from a major manufacturer, where every instance has the same ANDROID_ID.

The below solution is not a good one coz the value survives device wipes (“Factory resets”) and thus you could end up making a nasty mistake when one of your customers wipes their device and passes it on to another person.

You get the imei number of the device using the below

  TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
  telephonyManager.getDeviceId();

http://developer.android.com/reference/android/telephony/TelephonyManager.html#getDeviceId%28%29

Add this is manifest

<uses-permission android:name="android.permission.READ_PHONE_STATE"/>

Debug/run standard java in Visual Studio Code IDE and OS X?

There is a much easier way to run Java, no configuration needed:

  1. Install the Code Runner Extension
  2. Open your Java code file in Text Editor, then use shortcut Ctrl+Alt+N, or press F1 and then select/type Run Code, or right click the Text Editor and then click Run Code in context menu, the code will be compiled and run, and the output will be shown in the Output Window.

runJave

adding a datatable in a dataset

you have to set the tableName you want to your dtimage that is for instance

dtImage.TableName="mydtimage";


if(!ds.Tables.Contains(dtImage.TableName))
        ds.Tables.Add(dtImage);

it will be reflected in dataset because dataset is a container of your datatable dtimage and you have a reference on your dtimage

How to check if a variable is a dictionary in Python?

You could use if type(ele) is dict or use isinstance(ele, dict) which would work if you had subclassed dict:

d = {'abc': 'abc', 'def': {'ghi': 'ghi', 'jkl': 'jkl'}}
for element in d.values():
    if isinstance(element, dict):
       for k, v in element.items():
           print(k,' ',v)

How to find event listeners on a DOM node when debugging or from the JavaScript code?

Use getEventListeners in Google Chrome:

getEventListeners(document.getElementByID('btnlogin'));
getEventListeners($('#btnlogin'));

how to stop a for loop

Others ways to do the same is:

el = L[0][0]
m=len(L)

print L == [[el]*m]*m

Or:

first_el = L[0][0]
print all(el == first_el for inner_list in L for el in inner_list)

How to make JavaScript execute after page load?

Look at hooking document.onload or in jQuery $(document).load(...).

ActionBarActivity: cannot be resolved to a type

There is a mistake in your 'andrroid-sdk' folder. You selected some features while creating new project which need some components to import. It is needed to download a special android library and place it in android-sdk folder. For me it works fine: 1-Create a folder with name extras in your android-sdk folder 2-Create a folder with name android in extras 3-Download this file.(In my case I need this library) 4-Unzip it and copy the content (support folder) in the current android folder 5-close Eclipse and start it again 6-create your project again

I hope it to work for you.

What exactly is \r in C language?

That is not always true; it only works in Windows.
For interacting with terminal in putty, Linux shell,... it will be used for returning the cursor to the beginning of line. following picture shows the usage of that:

Without '\r':

Data comes without '\r' to the putty terminal, it has just '\n'.
it means that data will be printed just in next line.

enter image description here

With '\r':

Data comes with '\r', i.e. string ends with '\r\n'. So the cursor in putty terminal not only will go to the next line but also at the beginning of line

enter image description here

Toad for Oracle..How to execute multiple statements?

I prefer the Execute via SQL*Plus option. It's in the little down-arrow menu under the "Execute as script" toolbar button.

How to get the index of an item in a list in a single step?

That's all fine and good -- but what if you want to select an existing element as the default? In my issue there is no "--select a value--" option.

Here's my code -- you could make it into a one liner if you didn't want to check for no results I suppose...

private void LoadCombo(ComboBox cb, string itemType, string defVal = "")
{
    cb.DisplayMember = "Name";
    cb.ValueMember = "ItemCode";
    cb.DataSource = db.Items.Where(q => q.ItemTypeId == itemType).ToList();

    if (!string.IsNullOrEmpty(defVal))
    {
        var i = ((List<GCC_Pricing.Models.Item>)cb.DataSource).FindIndex(q => q.ItemCode == defVal);
        if (i>=0) cb.SelectedIndex = i;
    }
}

MaxLength Attribute not generating client-side validation attributes

Try using the [StringLength] attribute:

[Required(ErrorMessage = "Name is required.")]
[StringLength(40, ErrorMessage = "Name cannot be longer than 40 characters.")]
public string Name { get; set; }

That's for validation purposes. If you want to set for example the maxlength attribute on the input you could write a custom data annotations metadata provider as shown in this post and customize the default templates.

Showing ValueError: shapes (1,3) and (1,3) not aligned: 3 (dim 1) != 1 (dim 0)

The column of the first matrix and the row of the second matrix should be equal and the order should be like this only

column of first matrix = row of second matrix

and do not follow the below step

row of first matrix  = column of second matrix

it will throw an error

What is 'PermSize' in Java?

A quick definition of the "permanent generation":

"The permanent generation is used to hold reflective data of the VM itself such as class objects and method objects. These reflective objects are allocated directly into the permanent generation, and it is sized independently from the other generations." [ref]

In other words, this is where class definitions go (and this explains why you may get the message OutOfMemoryError: PermGen space if an application loads a large number of classes and/or on redeployment).

Note that PermSize is additional to the -Xmx value set by the user on the JVM options. But MaxPermSize allows for the JVM to be able to grow the PermSize to the amount specified. Initially when the VM is loaded, the MaxPermSize will still be the default value (32mb for -client and 64mb for -server) but will not actually take up that amount until it is needed. On the other hand, if you were to set BOTH PermSize and MaxPermSize to 256mb, you would notice that the overall heap has increased by 256mb additional to the -Xmx setting.

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

git remote update && git status 

Found this on the answer to Check if pull needed in Git

git remote update to bring your remote refs up to date. Then you can do one of several things, such as:

  1. git status -uno will tell you whether the branch you are tracking is ahead, behind or has diverged. If it says nothing, the local and remote are the same.

  2. git show-branch *master will show you the commits in all of the branches whose names end in master (eg master and origin/master).

If you use -v with git remote update you can see which branches got updated, so you don't really need any further commands.

Multiple WHERE Clauses with LINQ extension methods

you can use && and write all conditions in to the same where clause, or you can .Where().Where().Where()... and so on.

How can I build XML in C#?

new XElement("Foo",
       from s in nameValuePairList
       select
             new XElement("Bar",
                  new XAttribute("SomeAttr", "SomeAttrValue"),
                          new XElement("Name", s.Name),
                          new XElement("Value", s.Value)
                         )
            );

how to delete default values in text field using selenium?

The following function will delete the input character one by one till the input field is empty using PromiseWhile

driver.clearKeys = function(element, value){
  return element.getAttribute('value').then(function(val) {
    if (val.length > 0) {
      return new Promise(function(resolve, reject) {
        var len;
        len = val.length;
        return promiseWhile(function() { 
          return 0 < len;
        }, function() {
          return new Promise(function(resolve, reject) {
            len--;
            return element.sendKeys(webdriver.Key.BACK_SPACE).then(function()              {
              return resolve(true);
            });
          });
        }).then(function() {
          return resolve(true);
        });
      });
    }

How to list branches that contain a given commit?

You may run:

git log <SHA1>..HEAD --ancestry-path --merges

From comment of last commit in the output you may find original branch name

Example:

       c---e---g--- feature
      /         \
-a---b---d---f---h---j--- master

git log e..master --ancestry-path --merges

commit h
Merge: g f
Author: Eugen Konkov <>
Date:   Sat Oct 1 00:54:18 2016 +0300

    Merge branch 'feature' into master

How do you use the ? : (conditional) operator in JavaScript?

This is probably not exactly the most elegant way to do this. But for someone who is not familiar with ternary operators, this could prove useful. My personal preference is to do 1-liner fallbacks instead of condition-blocks.

  // var firstName = 'John'; // Undefined
  var lastName = 'Doe';

  // if lastName or firstName is undefined, false, null or empty => fallback to empty string
  lastName = lastName || '';
  firstName = firstName || '';

  var displayName = '';

  // if lastName (or firstName) is undefined, false, null or empty
  // displayName equals 'John' OR 'Doe'

  // if lastName and firstName are not empty
  // a space is inserted between the names
  displayName = (!lastName || !firstName) ? firstName + lastName : firstName + ' ' + lastName;


  // if display name is undefined, false, null or empty => fallback to 'Unnamed'
  displayName = displayName || 'Unnamed';

  console.log(displayName);

Ternary Operator

MVC Redirect to View from jQuery with parameters

If your click handler is successfully called then this should work:

$('#results').on('click', '.item', function () {
            var NestId = $(this).data('id');
            var url = "/Artists/Details?NestId=" + NestId; 
            window.location.href = url; 
        })

EDIT: In this particular case given that the action method parameter is a string which is nullable, then if NestId == null, won't cause any exception at all, given that the ModelBinder won't complain about it.

Link to Flask static files with url_for

In my case I had special instruction into nginx configuration file:

location ~ \.(js|css|png|jpg|gif|swf|ico|pdf|mov|fla|zip|rar)$ {
            try_files $uri =404;
    }

All clients have received '404' because nginx nothing known about Flask.

I hope it help someone.

How do I get Flask to run on port 80?

you can easily disable any process running on port 80 and then run this command

flask run --host 0.0.0.0 --port 80

or if u prefer running it within the .py file

if __name__ == "__main__":
    app.run(host=0.0.0.0, port=80)

Division of integers in Java

You don't even need doubles for this. Just multiply by 100 first and then divide. Otherwise the result would be less than 1 and get truncated to zero, as you saw.

edit: or if overflow is likely, if it would overflow (ie the dividend is bigger than 922337203685477581), divide the divisor by 100 first.

Make scrollbars only visible when a Div is hovered over?

If you are only concern about showing/hiding, this code would work just fine:

$("#leftDiv").hover(function(){$(this).css("overflow","scroll");},function(){$(this).css("overflow","hidden");});

However, it might modify some elements in your design, in case you are using width=100%, considering that when you hide the scrollbar, it creates a little bit of more room for your width.

How to get the first 2 letters of a string in Python?

In python strings are list of characters, but they are not explicitly list type, just list-like (i.e. it can be treated like a list). More formally, they're known as sequence (see http://docs.python.org/2/library/stdtypes.html#sequence-types-str-unicode-list-tuple-bytearray-buffer-xrange):

>>> a = 'foo bar'
>>> isinstance(a, list)
False
>>> isinstance(a, str)
True

Since strings are sequence, you can use slicing to access parts of the list, denoted by list[start_index:end_index] see Explain Python's slice notation . For example:

>>> a = [1,2,3,4]
>>> a[0]
1 # first element, NOT a sequence.
>>> a[0:1]
[1] # a slice from first to second, a list, i.e. a sequence.
>>> a[0:2]
[1, 2]
>>> a[:2]
[1, 2]

>>> x = "foo bar"
>>> x[0:2]
'fo'
>>> x[:2]
'fo'

When undefined, the slice notation takes the starting position as the 0, and end position as len(sequence).

In the olden C days, it's an array of characters, the whole issue of dynamic vs static list sounds like legend now, see Python List vs. Array - when to use?

jQuery lose focus event

Like this:

$(selector).focusout(function () {
    //Your Code
});

Ubuntu, how do you remove all Python 3 but not 2

EDIT: As pointed out in recent comments, this solution may BREAK your system.

You most likely don't want to remove python3.

Please refer to the other answers for possible solutions.

Outdated answer (not recommended)

sudo apt-get remove 'python3.*'

How to add row in JTable?

To add row to JTable, one of the ways is:

1) Create table using DefaultTableModel:

        DefaultTableModel model = new DefaultTableModel();
        model.addColumn("Code");
        model.addColumn("Name");
        model.addColumn("Quantity");
        model.addColumn("Unit Price");
        model.addColumn("Price");
        JTable table = new JTable(model);

2) To add row:

        DefaultTableModel model = (DefaultTableModel) table.getModel();
        model.addRow(new Object[]{"Column 1", "Column 2", "Column 3","Column 4","Column 5"});

Setting default values to null fields when mapping with Jackson

There is no annotation to set default value.
You can set default value only on java class level:

public class JavaObject 
{
    public String notNullMember;

    public String optionalMember = "Value";
}

mysql datetime comparison

I know its pretty old but I just encounter the problem and there is what I saw in the SQL doc :

[For best results when using BETWEEN with date or time values,] use CAST() to explicitly convert the values to the desired data type. Examples: If you compare a DATETIME to two DATE values, convert the DATE values to DATETIME values. If you use a string constant such as '2001-1-1' in a comparison to a DATE, cast the string to a DATE.

I assume it's better to use STR_TO_DATE since they took the time to make a function just for that and also the fact that i found this in the BETWEEN doc...

Difference between Return and Break statements

break is used to exit (escape) the for-loop, while-loop, switch-statement that you are currently executing.

return will exit the entire method you are currently executing (and possibly return a value to the caller, optional).

So to answer your question (as others have noted in comments and answers) you cannot use either break nor return to escape an if-else-statement per se. They are used to escape other scopes.


Consider the following example. The value of x inside the while-loop will determine if the code below the loop will be executed or not:

void f()
{
   int x = -1;
   while(true)
   {
     if(x == 0)
        break;         // escape while() and jump to execute code after the the loop 
     else if(x == 1)
        return;        // will end the function f() immediately,
                       // no further code inside this method will be executed.

     do stuff and eventually set variable x to either 0 or 1
     ...
   }

   code that will be executed on break (but not with return).
   ....
}

How to use Java property files?

I have written on this property framework for the last year. It will provide of multiple ways to load properties, and have them strongly typed as well.

Have a look at http://sourceforge.net/projects/jhpropertiestyp/

JHPropertiesTyped will give the developer strongly typed properties. Easy to integrate in existing projects. Handled by a large series for property types. Gives the ability to one-line initialize properties via property IO implementations. Gives the developer the ability to create own property types and property io's. Web demo is also available, screenshots shown above. Also have a standard implementation for a web front end to manage properties, if you choose to use it.

Complete documentation, tutorial, javadoc, faq etc is a available on the project webpage.

How to target only IE (any version) within a stylesheet?

Another working solution for IE specific styling is

<html data-useragent="Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)">

And then your selector

html[data-useragent*='MSIE 10.0'] body .my-class{
        margin-left: -0.4em;
    }

How to use registerReceiver method?

The whole code if somebody need it.

void alarm(Context context, Calendar calendar) {
    AlarmManager alarmManager = (AlarmManager)context.getSystemService(ALARM_SERVICE);

    final String SOME_ACTION = "com.android.mytabs.MytabsActivity.AlarmReceiver";
    IntentFilter intentFilter = new IntentFilter(SOME_ACTION);

    AlarmReceiver mReceiver = new AlarmReceiver();
    context.registerReceiver(mReceiver, intentFilter);

    Intent anotherIntent = new Intent(SOME_ACTION);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, anotherIntent, 0);
    alramManager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);

    Toast.makeText(context, "Added", Toast.LENGTH_LONG).show();
}

class AlarmReceiver extends BroadcastReceiver {     
    @Override
    public void onReceive(Context context, Intent arg1) {
        Toast.makeText(context, "Started", Toast.LENGTH_LONG).show();
    }
}

How to present UIAlertController when not in a view controller?

Swift 5

It's important to hide the window after showing the message.

func showErrorMessage(_ message: String) {
    let alertWindow = UIWindow(frame: UIScreen.main.bounds)
    alertWindow.rootViewController = UIViewController()

    let alertController = UIAlertController(title: "Error", message: message, preferredStyle: UIAlertController.Style.alert)
    alertController.addAction(UIAlertAction(title: "Close", style: UIAlertAction.Style.cancel, handler: { _ in
        alertWindow.isHidden = true
    }))
    
    alertWindow.windowLevel = UIWindow.Level.alert + 1;
    alertWindow.makeKeyAndVisible()
    alertWindow.rootViewController?.present(alertController, animated: true, completion: nil)
}

Reverse engineering from an APK file to a project

Not really. There are a number of dex disassembler/decompiler suites out there such as smali, or dex2jar that will generate semi-humanreadable output (in the case of dex2jar, you can get java code through the use of something like JD-GUI but the process is not perfect and it is very unlikely that you'll be able to 100% recreate your source code. However, it could potentially give you a place to start rebuilding your source tree.

Disable asp.net button after click to prevent double clicking

If you want to prevent double clicking due to a slow responding server side code then this works fine:

<asp:Button ... OnClientClick="this.disabled=true;" UseSubmitBehavior="false" />

Try putting a Threading.Thread.Sleep(5000) on the _Click() event on the server and you will see the button is disabled for the time that the server is processing the click event.

No need for server side code to re-enable the button either!

jQuery Multiple ID selectors

Make sure upload plugin implements this.each in it so that it will execute the logic for all the matching elements. It should ideally work

$("#upload_link,#upload_link2,#upload_link3").upload(function(){ });

Aborting a shell script if any command returns a non-zero value

To add to the accepted answer:

Bear in mind that set -e sometimes is not enough, specially if you have pipes.

For example, suppose you have this script

#!/bin/bash
set -e 
./configure  > configure.log
make

... which works as expected: an error in configure aborts the execution.

Tomorrow you make a seemingly trivial change:

#!/bin/bash
set -e 
./configure  | tee configure.log
make

... and now it does not work. This is explained here, and a workaround (Bash only) is provided:

#!/bin/bash
set -e 
set -o pipefail

./configure  | tee configure.log
make

What is the difference between response.sendRedirect() and request.getRequestDispatcher().forward(request,response)

Simply difference between Forward(ServletRequest request, ServletResponse response) and sendRedirect(String url) is

forward():

  1. The forward() method is executed in the server side.
  2. The request is transfer to other resource within same server.
  3. It does not depend on the client’s request protocol since the forward () method is provided by the servlet container.
  4. The request is shared by the target resource.
  5. Only one call is consumed in this method.
  6. It can be used within server.
  7. We cannot see forwarded message, it is transparent.
  8. The forward() method is faster than sendRedirect() method.
  9. It is declared in RequestDispatcher interface.

sendRedirect():

  1. The sendRedirect() method is executed in the client side.
  2. The request is transfer to other resource to different server.
  3. The sendRedirect() method is provided under HTTP so it can be used only with HTTP clients.
  4. New request is created for the destination resource.
  5. Two request and response calls are consumed.
  6. It can be used within and outside the server.
  7. We can see redirected address, it is not transparent.
  8. The sendRedirect() method is slower because when new request is created old request object is lost.
  9. It is declared in HttpServletResponse.

"Could not find Developer Disk Image"

This solution works only if you create in Xcode 7 the directory "10.0" and you have a mistake in your sentence:

ln -s /Applications/Xcode_8.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/10.0 \(14A345\) /Applications/Xcode_7.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/10.0

HTML5 - mp4 video does not play in IE9

Internet Explorer and Edge do not support some MP4 formats that Chrome does. You can use ffprobe to see the exact MP4 format. In my case I have these two videos:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'a.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf56.40.101
  Duration: 00:00:12.10, start: 0.000000, bitrate: 287 kb/s
    Stream #0:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 / 0x31637661), yuv444p, 1000x1000 [SAR 1:1 DAR 1:1], 281 kb/s, 60 fps, 60 tbr, 15360 tbn, 120 tbc (default)
    Metadata:
      handler_name    : VideoHandler


Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'b.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.66.102
  Duration: 00:00:33.83, start: 0.000000, bitrate: 505 kb/s
    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 1280x680, 504 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Metadata:
      handler_name    : VideoHandler

Both play fine in Chrome, but the first one fails in IE and Edge. The problem is that IE and Edge don't support yuv444. You can convert to a shittier colourspace like this:

ffmpeg -i input.mp4 -pix_fmt yuv420p output.mp4

MVC web api: No 'Access-Control-Allow-Origin' header is present on the requested resource

I know that people will probably find this very obvious at first, but really think about this. This can often happen if you've done something wrong.

For instance, I've had this problem because I didn't add a host entry to my hosts file. The real problem was DNS resolution. Or I just got the base URL wrong.

Sometimes I get this error if the identity token came from one server, but I'm trying to use it on another.

Sometimes you'll get this error if you've got the resource wrong.

You might get this if you put the CORS middleware too late in the chain.

Remove unused imports in Android Studio

It is very Simple Just Follow the below step.

  1. Switch your project in Project Mode.

enter image description here

  1. Then right-click on project name.
  2. The final step is to select the Optimize imports from popup menu.

Enjoy!!

Python socket.error: [Errno 111] Connection refused

The problem obviously was (as you figured it out) that port 36250 wasn't open on the server side at the time you tried to connect (hence connection refused). I can see the server was supposed to open this socket after receiving SEND command on another connection, but it apparently was "not opening [it] up in sync with the client side".

Well, the main reason would be there was no synchronisation whatsoever. Calling:

cs.send("SEND " + FILE)
cs.close()

would just place the data into a OS buffer; close would probably flush the data and push into the network, but it would almost certainly return before the data would reach the server. Adding sleep after close might mitigate the problem, but this is not synchronisation.

The correct solution would be to make sure the server has opened the connection. This would require server sending you some message back (for example OK, or better PORT 36250 to indicate where to connect). This would make sure the server is already listening.

The other thing is you must check the return values of send to make sure how many bytes was taken from your buffer. Or use sendall.

(Sorry for disturbing with this late answer, but I found this to be a high traffic question and I really didn't like the sleep idea in the comments section.)

How to get Selected Text from select2 when using <input>

In Select2 version 4 each option has the same properties of the objects in the list;

if you have the object

Obj = {
  name: "Alberas",
  description: "developer",
  birthDate: "01/01/1990"
}

then you retrieve the selected data

var data = $('#id-selected-input').select2('data');
console.log(data[0].name);
console.log(data[0].description);
console.log(data[0].birthDate);
 

How to check a channel is closed or not without reading it?

In a hacky way it can be done for channels which one attempts to write to by recovering the raised panic. But you cannot check if a read channel is closed without reading from it.

Either you will

  • eventually read the "true" value from it (v <- c)
  • read the "true" value and 'not closed' indicator (v, ok <- c)
  • read a zero value and the 'closed' indicator (v, ok <- c)
  • will block in the channel read forever (v <- c)

Only the last one technically doesn't read from the channel, but that's of little use.

gcc warning" 'will be initialized after'

If you're seeing errors from library headers and you're using GCC, then you can disable warnings by including the headers using -isystem instead of -I.

Similar features exist in clang.

If you're using CMake, you can specify SYSTEM for include_directories.

Jmeter - Run .jmx file through command line and get the summary report in a excel

To get the results in excel like file, you have one option to get it done with csv file. Use below commands with provided options.

jmeter -n -t /path-to-jmeter-test/file.jmx -l TestResults.csv
-n states Non GUI mode
-t states Test JMX File
-l state Log the results in provided file

Also you can pass any results related parameters dynamically in command line arguments using -Jprop.name=value which are already defined in jmeter.properties in bin folder.

Differentiate between function overloading and function overriding

Function overloading - functions with same name, but different number of arguments

Function overriding - concept of inheritance. Functions with same name and same number of arguments. Here the second function is said to have overridden the first

Iterate all files in a directory using a 'for' loop

To iterate through all files and folders you can use

for /F "delims=" %%a in ('dir /b /s') do echo %%a

To iterate through all folders only not with files, then you can use

for /F "delims=" %%a in ('dir /a:d /b /s') do echo %%a

Where /s will give all results throughout the directory tree in unlimited depth. You can skip /s if you want to iterate through the content of that folder not their sub folder

Implementing search in iteration

To iterate through a particular named files and folders you can search for the name and iterate using for loop

for /F "delims=" %%a in ('dir "file or folder name" /b /s') do echo %%a

To iterate through a particular named folders/directories and not files, then use /AD in the same command

for /F "delims=" %%a in ('dir "folder name" /b /AD /s') do echo %%a

How to change ProgressBar's progress indicator color in Android

Create a drawable resource what background you need, in my case I named it bg_custom_progressbar.xml

<?xml version="1.0" encoding="utf-8"?>

<item>
    <shape android:shape="rectangle" >
        <corners android:radius="5dp"/>

        <gradient
            android:angle="180"
            android:endColor="#DADFD6"
            android:startColor="#AEB9A3" />
    </shape>
</item>
<item>
    <clip>
        <shape android:shape="rectangle" >
            <corners android:radius="5dp" />

            <gradient
                android:angle="180"
                android:endColor="#44CF4A"
                android:startColor="#2BB930" />
        </shape>
    </clip>
</item>
<item>
    <clip>
        <shape android:shape="rectangle" >
            <corners android:radius="5dp" />

            <gradient
                android:angle="180"
                android:endColor="#44CF4A"
                android:startColor="#2BB930" />
        </shape>
    </clip>
</item>

Then use this custom background like

 <ProgressBar
                android:id="@+id/progressBarBarMenuHome"
                style="?android:attr/progressBarStyleHorizontal"
                android:layout_width="match_parent"
                android:layout_height="20dp"
                android:layout_marginStart="10dp"
                android:layout_marginEnd="10dp"
                android:layout_marginBottom="6dp"
                android:indeterminate="false"
                android:max="100"
                android:minWidth="200dp"
                android:minHeight="50dp"
                android:progress="10"
                android:progressDrawable="@drawable/bg_custom_progressbar" />

Its works fine for me

Difference between text and varchar (character varying)

On PostgreSQL manual

There is no performance difference among these three types, apart from increased storage space when using the blank-padded type, and a few extra CPU cycles to check the length when storing into a length-constrained column. While character(n) has performance advantages in some other database systems, there is no such advantage in PostgreSQL; in fact character(n) is usually the slowest of the three because of its additional storage costs. In most situations text or character varying should be used instead.

I usually use text

References: http://www.postgresql.org/docs/current/static/datatype-character.html

creating triggers for After Insert, After Update and After Delete in SQL

(Update: overlooked a fault in the matter, I have corrected)

(Update2: I wrote from memory the code screwed up, repaired it)

(Update3: check on SQLFiddle)

create table Derived_Values
  (
    BusinessUnit nvarchar(100) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)
    )

go

ALTER TABLE Derived_Values ADD CONSTRAINT PK_Derived_Values
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

create table Derived_Values_Test
  (
    BusinessUnit nvarchar(150)
    ,Questions nvarchar(100)
    ,Answer nvarchar(100)
    )

go

CREATE TRIGGER trgAfterUpdate ON  [Derived_Values]
FOR UPDATE
AS  
begin
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Updated Record -- After Update Trigger.'

    insert into 
        [Derived_Values_Test]
        --(BusinessUnit,Questions, Answer) 
    SELECT 
        @BusinessUnit + i.BusinessUnit, i.Questions, i.Answer
    FROM 
        inserted i
        inner join deleted d on i.BusinessUnit = d.BusinessUnit
end

go

CREATE TRIGGER trgAfterDelete ON  [Derived_Values]
FOR UPDATE
AS  
begin
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Deleted Record -- After Delete Trigger.'

    insert into 
        [Derived_Values_Test]
        --(BusinessUnit,Questions, Answer) 
    SELECT 
        @BusinessUnit + d.BusinessUnit, d.Questions, d.Answer
    FROM 
        deleted d
end

go

insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q11', 'A11')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q12', 'A12')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q21', 'A21')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q22', 'A22')

UPDATE Derived_Values SET Answer='Updated Answers A11' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q11');
UPDATE Derived_Values SET Answer='Updated Answers A12' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q12');
UPDATE Derived_Values SET Answer='Updated Answers A21' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q21');
UPDATE Derived_Values SET Answer='Updated Answers A22' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q22');

delete Derived_Values;

and then:

SELECT * FROM Derived_Values;
go

select * from Derived_Values_Test;


Record Count: 0;

BUSINESSUNIT    QUESTIONS   ANSWER
Updated Record -- After Update Trigger.BU1  Q11 Updated Answers A11
Deleted Record -- After Delete Trigger.BU1  Q11 A11
Updated Record -- After Update Trigger.BU1  Q12 Updated Answers A12
Deleted Record -- After Delete Trigger.BU1  Q12 A12
Updated Record -- After Update Trigger.BU2  Q21 Updated Answers A21
Deleted Record -- After Delete Trigger.BU2  Q21 A21
Updated Record -- After Update Trigger.BU2  Q22 Updated Answers A22
Deleted Record -- After Delete Trigger.BU2  Q22 A22

(Update4: If you want to sync: SQLFiddle)

create table Derived_Values
  (
    BusinessUnit nvarchar(100) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)
    )

go

ALTER TABLE Derived_Values ADD CONSTRAINT PK_Derived_Values
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

create table Derived_Values_Test
  (
    BusinessUnit nvarchar(150) not null
    ,Questions nvarchar(100) not null
    ,Answer nvarchar(100)
    )

go

ALTER TABLE Derived_Values_Test ADD CONSTRAINT PK_Derived_Values_Test
PRIMARY KEY CLUSTERED (BusinessUnit, Questions);

CREATE TRIGGER trgAfterInsert ON  [Derived_Values]
FOR INSERT
AS  
begin
    insert
        [Derived_Values_Test]
        (BusinessUnit,Questions,Answer)
    SELECT 
        i.BusinessUnit, i.Questions, i.Answer
    FROM 
        inserted i
end

go


CREATE TRIGGER trgAfterUpdate ON  [Derived_Values]
FOR UPDATE
AS  
begin
    declare @BusinessUnit nvarchar(50)
    set @BusinessUnit = 'Updated Record -- After Update Trigger.'

    update
        [Derived_Values_Test]
    set
        --BusinessUnit = i.BusinessUnit
        --,Questions = i.Questions
        Answer = i.Answer
    from
        [Derived_Values]
        inner join inserted i 
    on
        [Derived_Values].BusinessUnit = i.BusinessUnit
        and
        [Derived_Values].Questions = i.Questions
end

go

CREATE TRIGGER trgAfterDelete ON  [Derived_Values]
FOR DELETE
AS  
begin
    delete 
        [Derived_Values_Test]
    from
        [Derived_Values_Test]
        inner join deleted d 
    on
        [Derived_Values_Test].BusinessUnit = d.BusinessUnit
        and
        [Derived_Values_Test].Questions = d.Questions
end

go

insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q11', 'A11')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU1', 'Q12', 'A12')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q21', 'A21')
insert Derived_Values (BusinessUnit,Questions, Answer) values ('BU2', 'Q22', 'A22')

UPDATE Derived_Values SET Answer='Updated Answers A11' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q11');
UPDATE Derived_Values SET Answer='Updated Answers A12' from Derived_Values WHERE (BusinessUnit = 'BU1') AND (Questions = 'Q12');
UPDATE Derived_Values SET Answer='Updated Answers A21' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q21');
UPDATE Derived_Values SET Answer='Updated Answers A22' from Derived_Values WHERE (BusinessUnit = 'BU2') AND (Questions = 'Q22');

--delete Derived_Values;

And then:

SELECT * FROM Derived_Values;
go

select * from Derived_Values_Test;


BUSINESSUNIT    QUESTIONS   ANSWER
BU1 Q11 Updated Answers A11
BU1 Q12 Updated Answers A12
BU2 Q21 Updated Answers A21
BU2 Q22 Updated Answers A22

BUSINESSUNIT    QUESTIONS   ANSWER
BU1 Q11 Updated Answers A11
BU1 Q12 Updated Answers A12
BU2 Q21 Updated Answers A21
BU2 Q22 Updated Answers A22

When to use AtomicReference in Java?

When do we use AtomicReference?

AtomicReference is flexible way to update the variable value atomically without use of synchronization.

AtomicReference support lock-free thread-safe programming on single variables.

There are multiple ways of achieving Thread safety with high level concurrent API. Atomic variables is one of the multiple options.

Lock objects support locking idioms that simplify many concurrent applications.

Executors define a high-level API for launching and managing threads. Executor implementations provided by java.util.concurrent provide thread pool management suitable for large-scale applications.

Concurrent collections make it easier to manage large collections of data, and can greatly reduce the need for synchronization.

Atomic variables have features that minimize synchronization and help avoid memory consistency errors.

Provide a simple example where AtomicReference should be used.

Sample code with AtomicReference:

String initialReference = "value 1";

AtomicReference<String> someRef =
    new AtomicReference<String>(initialReference);

String newReference = "value 2";
boolean exchanged = someRef.compareAndSet(initialReference, newReference);
System.out.println("exchanged: " + exchanged);

Is it needed to create objects in all multithreaded programs?

You don't have to use AtomicReference in all multi threaded programs.

If you want to guard a single variable, use AtomicReference. If you want to guard a code block, use other constructs like Lock /synchronized etc.

AngularJS - Passing data between pages

You need to create a service to be able to share data between controllers.

app.factory('myService', function() {
 var savedData = {}
 function set(data) {
   savedData = data;
 }
 function get() {
  return savedData;
 }

 return {
  set: set,
  get: get
 }

});

In your controller A:

myService.set(yourSharedData);

In your controller B:

$scope.desiredLocation = myService.get();

Remember to inject myService in the controllers by passing it as a parameter.

How to decode HTML entities using jQuery?

Without any jQuery:

_x000D_
_x000D_
function decodeEntities(encodedString) {_x000D_
  var textArea = document.createElement('textarea');_x000D_
  textArea.innerHTML = encodedString;_x000D_
  return textArea.value;_x000D_
}_x000D_
_x000D_
console.log(decodeEntities('1 &amp; 2')); // '1 & 2'
_x000D_
_x000D_
_x000D_

This works similarly to the accepted answer, but is safe to use with untrusted user input.


Security issues in similar approaches

As noted by Mike Samuel, doing this with a <div> instead of a <textarea> with untrusted user input is an XSS vulnerability, even if the <div> is never added to the DOM:

_x000D_
_x000D_
function decodeEntities(encodedString) {_x000D_
  var div = document.createElement('div');_x000D_
  div.innerHTML = encodedString;_x000D_
  return div.textContent;_x000D_
}_x000D_
_x000D_
// Shows an alert_x000D_
decodeEntities('<img src="nonexistent_image" onerror="alert(1337)">')
_x000D_
_x000D_
_x000D_

However, this attack is not possible against a <textarea> because there are no HTML elements that are permitted content of a <textarea>. Consequently, any HTML tags still present in the 'encoded' string will be automatically entity-encoded by the browser.

_x000D_
_x000D_
function decodeEntities(encodedString) {_x000D_
    var textArea = document.createElement('textarea');_x000D_
    textArea.innerHTML = encodedString;_x000D_
    return textArea.value;_x000D_
}_x000D_
_x000D_
// Safe, and returns the correct answer_x000D_
console.log(decodeEntities('<img src="nonexistent_image" onerror="alert(1337)">'))
_x000D_
_x000D_
_x000D_

Warning: Doing this using jQuery's .html() and .val() methods instead of using .innerHTML and .value is also insecure* for some versions of jQuery, even when using a textarea. This is because older versions of jQuery would deliberately and explicitly evaluate scripts contained in the string passed to .html(). Hence code like this shows an alert in jQuery 1.8:

_x000D_
_x000D_
//<!-- CDATA_x000D_
// Shows alert_x000D_
$("<textarea>")_x000D_
.html("<script>alert(1337);</script>")_x000D_
.text();_x000D_
_x000D_
//-->
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.2.3/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

* Thanks to Eru Penkman for catching this vulnerability.

Android load from URL to Bitmap

public static Bitmap getBitmapFromURL(String src) {
    try {
        URL url = new URL(src);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoInput(true);
        connection.connect();
        InputStream input = connection.getInputStream();
        Bitmap myBitmap = BitmapFactory.decodeStream(input);
        return myBitmap;
    } catch (IOException e) {
        // Log exception
        return null;
    }
}

showDialog deprecated. What's the alternative?

From http://developer.android.com/reference/android/app/Activity.html

public final void showDialog (int id) Added in API level 1

This method was deprecated in API level 13. Use the new DialogFragment class with FragmentManager instead; this is also available on older platforms through the Android compatibility package.

Simple version of showDialog(int, Bundle) that does not take any arguments. Simply calls showDialog(int, Bundle) with null arguments.

Why

  • A fragment that displays a dialog window, floating on top of its activity's window. This fragment contains a Dialog object, which it displays as appropriate based on the fragment's state. Control of the dialog (deciding when to show, hide, dismiss it) should be done through the API here, not with direct calls on the dialog.
  • Here is a nice discussion Android DialogFragment vs Dialog
  • Another nice discussion DialogFragment advantages over AlertDialog

How to solve?

More

OpenCV with Network Cameras

I enclosed C++ code for grabbing frames. It requires OpenCV version 2.0 or higher. The code uses cv::mat structure which is preferred to old IplImage structure.

#include "cv.h"
#include "highgui.h"
#include <iostream>

int main(int, char**) {
    cv::VideoCapture vcap;
    cv::Mat image;

    const std::string videoStreamAddress = "rtsp://cam_address:554/live.sdp"; 
    /* it may be an address of an mjpeg stream, 
    e.g. "http://user:pass@cam_address:8081/cgi/mjpg/mjpg.cgi?.mjpg" */

    //open the video stream and make sure it's opened
    if(!vcap.open(videoStreamAddress)) {
        std::cout << "Error opening video stream or file" << std::endl;
        return -1;
    }

    //Create output window for displaying frames. 
    //It's important to create this window outside of the `for` loop
    //Otherwise this window will be created automatically each time you call
    //`imshow(...)`, which is very inefficient. 
    cv::namedWindow("Output Window");

    for(;;) {
        if(!vcap.read(image)) {
            std::cout << "No frame" << std::endl;
            cv::waitKey();
        }
        cv::imshow("Output Window", image);
        if(cv::waitKey(1) >= 0) break;
    }   
}

Update You can grab frames from H.264 RTSP streams. Look up your camera API for details to get the URL command. For example, for an Axis network camera the URL address might be:

// H.264 stream RTSP address, where 10.10.10.10 is an IP address 
// and 554 is the port number
rtsp://10.10.10.10:554/axis-media/media.amp

// if the camera is password protected
rtsp://username:[email protected]:554/axis-media/media.amp

No newline after div?

Quoting Mr Initial Man from here:

Instead of this:

<div id="Top" class="info"></div><a href="#" class="a_info"></a>

Use this:

<span id="Top" class="info"></span><a href="#" class="a_info"></a>

Also, you could use this:

<div id="Top" class="info"><a href="#" class="a_info"></a></div>

And gostbustaz:

If you absoultely must use a <div>, you can set

div {
    display: inline;
}

in your stylesheet.

Of course, that essentially makes the <div> a <span>.

Is there a minlength validation attribute in HTML5?

I used maxlength and minlength with or without required and it worked for me very well for HTML5.

_x000D_
_x000D_
<input id="passcode" type="password" minlength="8" maxlength="10">
_x000D_
_x000D_
_x000D_

`

OwinStartup not firing

If you are seeing this issue with IIS hosting, but not when F5 debugging, try creating a new application in IIS.

This fixed it for me. (windows 10) In the end i deleted the "bad" IIS application and re-created an identical one with the same name.

Saving timestamp in mysql table using php

Better is use datatype varchar(15).

MySQL SELECT statement for the "length" of the field is greater than 1

How about:

SELECT * FROM sometable WHERE CHAR_LENGTH(LINK) > 1

Here's the MySql string functions page (5.0).

Note that I chose CHAR_LENGTH instead of LENGTH, as if there are multibyte characters in the data you're probably really interested in how many characters there are, not how many bytes of storage they take. So for the above, a row where LINK is a single two-byte character wouldn't be returned - whereas it would when using LENGTH.

Note that if LINK is NULL, the result of CHAR_LENGTH(LINK) will be NULL as well, so the row won't match.

$("#form1").validate is not a function

youll need to use the latest http://ajax.microsoft.com/ajax/jquery.validate/1.5.5/jquery.validate.js in conjunction with one of the Microsoft's CDN for getting your validation file.

What is the default stack size, can it grow, how does it work with garbage collection?

How much a stack can grow?

You can use a VM option named ss to adjust the maximum stack size. A VM option is usually passed using -X{option}. So you can use java -Xss1M to set the maximum of stack size to 1M.

Each thread has at least one stack. Some Java Virtual Machines(JVM) put Java stack(Java method calls) and native stack(Native method calls in VM) into one stack, and perform stack unwinding using a Managed to Native Frame, known as M2NFrame. Some JVMs keep two stacks separately. The Xss set the size of the Java Stack in most cases.

For many JVMs, they put different default values for stack size on different platforms.

Can we limit this growth?

When a method call occurs, a new stack frame will be created on the stack of that thread. The stack will contain local variables, parameters, return address, etc. In java, you can never put an object on stack, only object reference can be stored on stack. Since array is also an object in java, arrays are also not stored on stack. So, if you reduce the amount of your local primitive variables, parameters by grouping them into objects, you can reduce the space on stack. Actually, the fact that we cannot explicitly put objects on java stack affects the performance some time(cache miss).

Does stack has some default minimum value or default maximum value?

As I said before, different VMs are different, and may change over versions. See here.

how does garbage collection work on stack?

Garbage collections in Java is a hot topic. Garbage collection aims to collect unreachable objects in the heap. So that needs a definition of 'reachable.' Everything on the stack constitutes part of the root set references in GC. Everything that is reachable from every stack of every thread should be considered as live. There are some other root set references, like Thread objects and some class objects.

This is only a very vague use of stack on GC. Currently most JVMs are using a generational GC. This article gives brief introduction about Java GC. And recently I read a very good article talking about the GC on .net. The GC on oracle jvm is quite similar so I think that might also help you.

cast or convert a float to nvarchar?

DECLARE @MyFloat [float]

SET @MyFloat = 1000109360.050

SELECT REPLACE (RTRIM (REPLACE (REPLACE (RTRIM ((REPLACE (CAST (CAST (@MyFloat AS DECIMAL (38 ,18 )) AS VARCHAR( max)), '0' , ' '))), ' ' , '0'), '.', ' ')), ' ','.')

What's the UIScrollView contentInset property for?

It sets the distance of the inset between the content view and the enclosing scroll view.

Obj-C

aScrollView.contentInset = UIEdgeInsetsMake(0, 0, 0, 7.0);

Swift 5.0

aScrollView.contentInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 7.0)

Here's a good iOS Reference Library article on scroll views that has an informative screenshot (fig 1-3) - I'll replicate it via text here:

  _|?_cW_?_|_?_
   |       | 
---------------
   |content| ?
 ? |content| contentInset.top
cH |content|
 ? |content| contentInset.bottom
   |content| ?
---------------
  _|_______|___ 
             ?


   (cH = contentSize.height; cW = contentSize.width)

The scroll view encloses the content view plus whatever padding is provided by the specified content insets.

Is there an upper bound to BigInteger?

The first maximum you would hit is the length of a String which is 231-1 digits. It's much smaller than the maximum of a BigInteger but IMHO it loses much of its value if it can't be printed.

How to get cell value from DataGridView in VB.Net?

The line would be as shown below:

Dim x As Integer    
x = dgvName.Rows(yourRowIndex).Cells(yourColumnIndex).Value

Hash function for a string

Hash functions for algorithmic use have usually 2 goals, first they have to be fast, second they have to evenly distibute the values across the possible numbers. The hash function also required to give the all same number for the same input value.

if your values are strings, here are some examples for bad hash functions:

  1. string[0] - the ASCII characters a-Z are way more often then others
  2. string.lengh() - the most probable value is 1

Good hash functions tries to use every bit of the input while keeping the calculation time minimal. If you only need some hash code, try to multiply the bytes with prime numbers, and sum them.

nano error: Error opening terminal: xterm-256color

I had this problem connecting to http://sdf.org through Mac OS X Lion. I changed under Terminal Preferences (?+,) > Advanced pane, Declare Terminal as to VT-100.

I also marked Delete Sends Ctrl-H because this Mac connection was confusing zsh.

It appears to be working for my use case.

Fade In on Scroll Down, Fade Out on Scroll Up - based on element position in window

I tweaked your code a bit and made it more robust. In terms of progressive enhancement it's probaly better to have all the fade-in-out logic in JavaScript. In the example of myfunksyde any user without JavaScript sees nothing because of the opacity: 0;.

    $(window).on("load",function() {
    function fade() {
        var animation_height = $(window).innerHeight() * 0.25;
        var ratio = Math.round( (1 / animation_height) * 10000 ) / 10000;

        $('.fade').each(function() {

            var objectTop = $(this).offset().top;
            var windowBottom = $(window).scrollTop() + $(window).innerHeight();

            if ( objectTop < windowBottom ) {
                if ( objectTop < windowBottom - animation_height ) {
                    $(this).html( 'fully visible' );
                    $(this).css( {
                        transition: 'opacity 0.1s linear',
                        opacity: 1
                    } );

                } else {
                    $(this).html( 'fading in/out' );
                    $(this).css( {
                        transition: 'opacity 0.25s linear',
                        opacity: (windowBottom - objectTop) * ratio
                    } );
                }
            } else {
                $(this).html( 'not visible' );
                $(this).css( 'opacity', 0 );
            }
        });
    }
    $('.fade').css( 'opacity', 0 );
    fade();
    $(window).scroll(function() {fade();});
});

See it here: http://jsfiddle.net/78xjLnu1/16/

Cheers, Martin

Determine which element the mouse pointer is on top of in JavaScript

<!-- One simple solution to your problem could be like this: -->

<div>
<input type="text" id="fname" onmousemove="javascript: alert(this.id);" />
<!-- OR -->
<input type="text" id="fname" onclick="javascript: alert(this.id);" />
</div>
<!-- Both mousemove over the field & click on the field displays "fname"-->
<!-- Works fantastic in IE, FireFox, Chrome, Opera. -->
<!-- I didn't test it for Safari. -->

Convert NSDate to NSString

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:myNSDateInstance];
NSInteger year = [components year];
// NSInteger month = [components month];
NSString *yearStr = [NSString stringWithFormat:@"%ld", year];

How can I make Java print quotes, like "Hello"?

System.out.println("\"Hello\"")

How do I print out the value of this boolean? (Java)

There are a couple of ways to address your problem, however this is probably the most straightforward:

Your main method is static, so it does not have access to instance members (isLeapYear field and isLeapYear method. One approach to rectify this is to make both the field and the method static as well:

static boolean isLeapYear;
/* (snip) */
public static boolean isLeapYear(int year)
{
  /* (snip) */
}

Lastly, you're not actually calling your isLeapYear method (which is why you're not seeing any results). Add this line after int year = kboard.nextInt();:

isLeapYear(year);

That should be a start. There are some other best practices you could follow but for now just focus on getting your code to work; you can refactor later.

Specifying Font and Size in HTML table

The font tag has been deprecated for some time now.

That being said, the reason why both of your tables display with the same font size is that the 'size' attribute only accepts values ranging from 1 - 7. The smallest size is 1. The largest size is 7. The default size is 3. Any values larger than 7 will just display the same as if you had used 7, because 7 is the maximum value allowed.

And as @Alex H said, you should be using CSS for this.

TypeError : Unhashable type

You'll find that instances of list do not provide a __hash__ --rather, that attribute of each list is actually None (try print [].__hash__). Thus, list is unhashable.

The reason your code works with list and not set is because set constructs a single set of items without duplicates, whereas a list can contain arbitrary data.

Return Boolean Value on SQL Select Statement

Use 'Exists' which returns either 0 or 1.

The query will be like:

SELECT EXISTS(SELECT * FROM USER WHERE UserID = 20070022)

Difference between Key, Primary Key, Unique Key and Index in MySQL

Unique Keys: The columns in which no two rows are similar

Primary Key: Collection of minimum number of columns which can uniquely identify every row in a table (i.e. no two rows are similar in all the columns constituting primary key). There can be more than one primary key in a table. If there exists a unique-key then it is primary key (not "the" primary key) in the table. If there does not exist a unique key then more than one column values will be required to identify a row like (first_name, last_name, father_name, mother_name) can in some tables constitute primary key.

Index: used to optimize the queries. If you are going to search or sort the results on basis of some column many times (eg. mostly people are going to search the students by name and not by their roll no.) then it can be optimized if the column values are all "indexed" for example with a binary tree algorithm.

How can I switch word wrap on and off in Visual Studio Code?

If you want a permanent solution for wordwrapping lines, go to menu FilePreferenceSettings and change editor.wordWrap: "on". This will apply always.

However, we usually keep changing our preference to check code. So, I use the Alt + Z key to wrap written code of a file or you can go to menu ViewToggle Word Wrap. This applies whenever you want not always. And again Alt + Z to undo wordwrap (will show the full line in one line).

How can I check if mysql is installed on ubuntu?

You can use tool dpkg for managing packages in Debian operating system.

Example

dpkg --get-selections | grep mysql if it's listed as installed, you got it. Else you need to get it.

document.getElementById("remember").visibility = "hidden"; not working on a checkbox

you can use

style="display:none"

Ex:

<asp:TextBox ID="txbProv" runat="server" style="display:none"></asp:TextBox>

JAXB: How to ignore namespace during unmarshalling XML document?

Another way to add a default namespace to an XML Document before feeding it to JAXB is to use JDom:

  1. Parse XML to a Document
  2. Iterate through and set namespace on all Elements
  3. Unmarshall using a JDOMSource

Like this:

public class XMLObjectFactory {
    private static Namespace DEFAULT_NS = Namespace.getNamespace("http://tempuri.org/");

    public static Object createObject(InputStream in) {
        try {
            SAXBuilder sb = new SAXBuilder(false);
            Document doc = sb.build(in);
            setNamespace(doc.getRootElement(), DEFAULT_NS, true);
            Source src = new JDOMSource(doc);
            JAXBContext context = JAXBContext.newInstance("org.tempuri");
            Unmarshaller unmarshaller = context.createUnmarshaller();
            JAXBElement root = unmarshaller.unmarshal(src);
            return root.getValue();
        } catch (Exception e) {
            throw new RuntimeException("Failed to create Object", e);
        }
    }

    private static void setNamespace(Element elem, Namespace ns, boolean recurse) {
        elem.setNamespace(ns);
        if (recurse) {
            for (Object o : elem.getChildren()) {
                setNamespace((Element) o, ns, recurse);
            }
        }
    }

List all tables in postgresql information_schema

You may use also

select * from pg_tables where schemaname = 'information_schema'

In generall pg* tables allow you to see everything in the db, not constrained to your permissions (if you have access to the tables of course).

How to print without newline or space?

you want to print something in for loop right;but you don't want it print in new line every time.. for example:

 for i in range (0,5):
   print "hi"

 OUTPUT:
    hi
    hi
    hi
    hi
    hi

but you want it to print like this: hi hi hi hi hi hi right???? just add a comma after print "hi"

Example:

for i in range (0,5): print "hi", OUTPUT: hi hi hi hi hi

How to set focus on input field?

Just a newbie here, but I was abble to make it work in a ui.bootstrap.modal with this directive:

directives.directive('focus', function($timeout) {
    return {
        link : function(scope, element) {
            scope.$watch('idToFocus', function(value) {
                if (value === element[0].id) {
                    $timeout(function() {
                        element[0].focus();
                    });
                }
            });
        }
    };
});

and in the $modal.open method I used the folowing to indicate the element where the focus should be putted:

var d = $modal.open({
        controller : function($scope, $modalInstance) {
            ...
            $scope.idToFocus = "cancelaAteste";
    }
        ...
    });

on the template I have this:

<input id="myInputId" focus />

How to print a dictionary's key?

Since we're all trying to guess what "print a key name" might mean, I'll take a stab at it. Perhaps you want a function that takes a value from the dictionary and finds the corresponding key? A reverse lookup?

def key_for_value(d, value):
    """Return a key in `d` having a value of `value`."""
    for k, v in d.iteritems():
        if v == value:
            return k

Note that many keys could have the same value, so this function will return some key having the value, perhaps not the one you intended.

If you need to do this frequently, it would make sense to construct the reverse dictionary:

d_rev = dict(v,k for k,v in d.iteritems())

When should I use GC.SuppressFinalize()?

SupressFinalize tells the system that whatever work would have been done in the finalizer has already been done, so the finalizer doesn't need to be called. From the .NET docs:

Objects that implement the IDisposable interface can call this method from the IDisposable.Dispose method to prevent the garbage collector from calling Object.Finalize on an object that does not require it.

In general, most any Dispose() method should be able to call GC.SupressFinalize(), because it should clean up everything that would be cleaned up in the finalizer.

SupressFinalize is just something that provides an optimization that allows the system to not bother queuing the object to the finalizer thread. A properly written Dispose()/finalizer should work properly with or without a call to GC.SupressFinalize().

from list of integers, get number closest to a given value

Expanding upon Gustavo Lima's answer. The same thing can be done without creating an entirely new list. The values in the list can be replaced with the differentials as the FOR loop progresses.

def f_ClosestVal(v_List, v_Number):
"""Takes an unsorted LIST of INTs and RETURNS INDEX of value closest to an INT"""
for _index, i in enumerate(v_List):
    v_List[_index] = abs(v_Number - i)
return v_List.index(min(v_List))

myList = [1, 88, 44, 4, 4, -2, 3]
v_Num = 5
print(f_ClosestVal(myList, v_Num)) ## Gives "3," the index of the first "4" in the list.

How do I set up Android Studio to work completely offline?

for a complete offline android studio 3.5.0 installation - you need to download all these below components

android studio, gradle, android gradle plugin and sdk.

here is a detailed step by step Stackoverflow answer for the question

how to install android studio full offline

How can I get sin, cos, and tan to use degrees instead of radians?

Create your own conversion function that applies the needed math, and invoke those instead. http://en.wikipedia.org/wiki/Radian#Conversion_between_radians_and_degrees

How to execute an SSIS package from .NET?

Here is how to set variables in the package from code -

using Microsoft.SqlServer.Dts.Runtime;

private void Execute_Package()
    {           
        string pkgLocation = @"c:\test.dtsx";

        Package pkg;
        Application app;
        DTSExecResult pkgResults;
        Variables vars;

        app = new Application();
        pkg = app.LoadPackage(pkgLocation, null);

        vars = pkg.Variables;
        vars["A_Variable"].Value = "Some value";               

        pkgResults = pkg.Execute(null, vars, null, null, null);

        if (pkgResults == DTSExecResult.Success)
            Console.WriteLine("Package ran successfully");
        else
            Console.WriteLine("Package failed");
    }

MATLAB, Filling in the area between two sets of data, lines in one figure

Building off of @gnovice's answer, you can actually create filled plots with shading only in the area between the two curves. Just use fill in conjunction with fliplr.

Example:

x=0:0.01:2*pi;                  %#initialize x array
y1=sin(x);                      %#create first curve
y2=sin(x)+.5;                   %#create second curve
X=[x,fliplr(x)];                %#create continuous x value array for plotting
Y=[y1,fliplr(y2)];              %#create y values for out and then back
fill(X,Y,'b');                  %#plot filled area

enter image description here

By flipping the x array and concatenating it with the original, you're going out, down, back, and then up to close both arrays in a complete, many-many-many-sided polygon.

Auto Increment after delete in MySQL

What you're trying to do sounds dangerous, as that's not the intended use of AUTO_INCREMENT.

If you really want to find the lowest unused key value, don't use AUTO_INCREMENT at all, and manage your keys manually. However, this is NOT a recommended practice.

Take a step back and ask "why you need to recycle key values?" Do unsigned INT (or BIGINT) not provide a large enough key space?

Are you really going to have more than 18,446,744,073,709,551,615 unique records over the course of your application's lifetime?

Matching an empty input box using CSS

This worked for me:

For the HTML, add the required attribute to the input element

<input class="my-input-element" type="text" placeholder="" required />

For the CSS, use the :invalid selector to target the empty input

input.my-input-element:invalid {

}

Notes:

  • About required from w3Schools.com: "When present, it specifies that an input field must be filled out before submitting the form."

What is an index in SQL?

An index is used to speed up searching in the database. MySQL have some good documentation on the subject (which is relevant for other SQL servers as well): http://dev.mysql.com/doc/refman/5.0/en/mysql-indexes.html

An index can be used to efficiently find all rows matching some column in your query and then walk through only that subset of the table to find exact matches. If you don't have indexes on any column in the WHERE clause, the SQL server has to walk through the whole table and check every row to see if it matches, which may be a slow operation on big tables.

The index can also be a UNIQUE index, which means that you cannot have duplicate values in that column, or a PRIMARY KEY which in some storage engines defines where in the database file the value is stored.

In MySQL you can use EXPLAIN in front of your SELECT statement to see if your query will make use of any index. This is a good start for troubleshooting performance problems. Read more here: http://dev.mysql.com/doc/refman/5.0/en/explain.html

What is the equivalent of the C++ Pair<L,R> in Java?

As many others have already stated, it really depends on the use case if a Pair class is useful or not.

I think for a private helper function it is totally legitimate to use a Pair class if that makes your code more readable and is not worth the effort of creating yet another value class with all its boiler plate code.

On the other hand, if your abstraction level requires you to clearly document the semantics of the class that contains two objects or values, then you should write a class for it. Usually that's the case if the data is a business object.

As always, it requires skilled judgement.

For your second question I recommend the Pair class from the Apache Commons libraries. Those might be considered as extended standard libraries for Java:

https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/tuple/Pair.html

You might also want to have a look at Apache Commons' EqualsBuilder, HashCodeBuilder and ToStringBuilder which simplify writing value classes for your business objects.

Using intents to pass data between activities

Main Activity

public class MainActivity extends Activity {

    EditText user, password;
    Button login;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        user = (EditText) findViewById(R.id.username_edit);
        password = (EditText) findViewById(R.id.edit_password);
        login = (Button) findViewById(R.id.btnSubmit);
        login.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this,Second.class);

                String uservalue = user.getText().toString();
                String name_value = password.getText().toString();
                String password_value = password.getText().toString();

                intent.putExtra("username", uservalue);
                intent.putExtra("password", password_value);
                startActivity(intent);
            }
        });
    }
}

Second Activity in which you want to receive Data

public class Second extends Activity{

    EditText name, pass;
    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.second_activity);

        name = (EditText) findViewById(R.id.editText1);
        pass = (EditText) findViewById(R.id.editText2);

        String value = getIntent().getStringExtra("username");
        String pass_val = getIntent().getStringExtra("password");
        name.setText(value);
        pass.setText(pass_val);
    }
}

CSS Image size, how to fill, but not stretch?

Enhancement on the accepted answer by @afonsoduarte.
in case you are using bootstrap


There are three differences:
  1. Providing width:100% on the style.
    This is helpful if you are using bootstrap and want the image to stretch all the available width.

  2. Specifying the height property is optional, You can remove/keep it as you need

    .cover {
       object-fit: cover;
       width: 100%;
       /*height: 300px;  optional, you can remove it, but in my case it was good */
    }
    
  3. By the way, there is NO need to provide the height and width attributes on the image element because they will be overridden by the style.
    so it is enough to write something like this.

    <img class="cover" src="url to img ..."  />
    

RecyclerView vs. ListView

Major advantage :

ViewHolder is not available by default in ListView. We will be creating explicitly inside the getView(). RecyclerView has inbuilt Viewholder.

How to fix Python indentation

If you're lazy (like me), you can also download a trial version of Wingware Python IDE, which has an auto-fix tool for messed up indentation. It works pretty well. http://www.wingware.com/

:not(:empty) CSS selector is not working?

You could try using :placeholder-shown...

_x000D_
_x000D_
input {
  padding: 10px 15px;
  font-size: 16px;
  border-radius: 5px;
  border: 2px solid lightblue;
  outline: 0;
  font-weight:bold;
  transition: border-color 200ms;
  font-family: sans-serif;
}

.validation {
  opacity: 0;
  font-size: 12px;
  font-family: sans-serif;
  color: crimson;
  transition: opacity;
}

input:required:valid {
  border-color: forestgreen;
}

input:required:invalid:not(:placeholder-shown) {
  border-color: crimson;
}

input:required:invalid:not(:placeholder-shown) + .validation {
  opacity: 1;
}

  
_x000D_
<input type="email" placeholder="e-mail" required>
<div class="validation">Not valid</span>
_x000D_
_x000D_
_x000D_

no great support though... caniuse

Jump to function definition in vim

1- install exuberant ctags. If you're using osx, this article shows a little trick: http://www.runtime-era.com/2012/05/exuberant-ctags-in-osx-107.html

2- If you only wish to include the ctags for the files in your directory only, run this command in your directory:

ctags -R

This will create a "tags" file for you.

3- If you're using Ruby and wish to include the ctags for your gems (this has been really helpful for me with RubyMotion and local gems that I have developed), do the following:

ctags --exclude=.git --exclude='*.log' -R * `bundle show --paths`

credit: https://coderwall.com/p/lv1qww (Note that I omitted the -e option which generates tags for emacs instead of vim)

4- Add the following line to your ~/.vimrc

set autochdir 
set tags+=./tags;

(Why the semi colon: http://vim.wikia.com/wiki/Single_tags_file_for_a_source_tree )

5- Go to the word you'd like to follow and hit ctrl + ] ; if you'd like to go back, use ctrl+o (source: https://stackoverflow.com/a/53929/226255)

What regex will match every character except comma ',' or semi-colon ';'?

Use character classes. A character class beginning with caret will match anything not in the class.

[^,;]

Why es6 react component works only with "export default"?

Exporting without default means it's a "named export". You can have multiple named exports in a single file. So if you do this,

class Template {}
class AnotherTemplate {}

export { Template, AnotherTemplate }

then you have to import these exports using their exact names. So to use these components in another file you'd have to do,

import {Template, AnotherTemplate} from './components/templates'

Alternatively if you export as the default export like this,

export default class Template {}

Then in another file you import the default export without using the {}, like this,

import Template from './components/templates'

There can only be one default export per file. In React it's a convention to export one component from a file, and to export it is as the default export.

You're free to rename the default export as you import it,

import TheTemplate from './components/templates'

And you can import default and named exports at the same time,

import Template,{AnotherTemplate} from './components/templates'

Change default text in input type="file"?

I made a script and published it at GitHub: get selectFile.js Easy to use, feel free to clone.


HTML

<input type=file hidden id=choose name=choose>
<input type=button onClick=getFile.simulate() value=getFile>
<label id=selected>Nothing selected</label>


JS

var getFile = new selectFile;
getFile.targets('choose','selected');


DEMO

jsfiddle.net/Thielicious/4oxmsy49/

calling a function from class in python - different way

class MathsOperations:
    def __init__ (self, x, y):
        self.a = x
        self.b = y
    def testAddition (self):
        return (self.a + self.b)

    def testMultiplication (self):
        return (self.a * self.b)

then

temp = MathsOperations()
print(temp.testAddition())

How to compare two Carbon Timestamps?

First, convert the timestamp using the built-in eloquent functionality, as described in this answer.

Then you can just use Carbon's min() or max() function for comparison. For example:

$dt1 = Carbon::create(2012, 1, 1, 0, 0, 0); $dt2 = Carbon::create(2014, 1, 30, 0, 0, 0); echo $dt1->min($dt2);

This will echo the lesser of the two dates, which in this case is $dt1.

See http://carbon.nesbot.com/docs/

Using Mockito's generic "any()" method

This should work

import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.verify;

verify(bar).DoStuff(any(Foo[].class));

How to determine the Schemas inside an Oracle Data Pump Export file

You need to search for OWNER_NAME.

cat -v dumpfile.dmp | grep -o '<OWNER_NAME>.*</OWNER_NAME>' | uniq -u

cat -v turn the dumpfile into visible text.

grep -o shows only the match so we don't see really long lines

uniq -u removes duplicate lines so you see less output.

This works pretty well, even on large dump files, and could be tweaked for usage in a script.

How to add Drop-Down list (<select>) programmatically?

const countryResolver = (data = [{}]) => {
    const countrySelecter = document.createElement('select');
    countrySelecter.className = `custom-select`;
    countrySelecter.id = `countrySelect`;
    countrySelecter.setAttribute("aria-label", "Example select with button addon");

    let opt = document.createElement("option");
    opt.text = "Select language";
    opt.disabled = true;
    countrySelecter.add(opt, null);
    let i = 0;
    for (let item of data) {
        let opt = document.createElement("option");
        opt.value = item.Id;
        opt.text = `${i++}. ${item.Id} - ${item.Value}(${item.Comment})`;
        countrySelecter.add(opt, null);
    }
    return countrySelecter;
};

How do you run a single test/spec file in RSpec?

This question is an old one, but it shows up at the top of Google when searching for how to run a single test. I don't know if it's a recent addition, but to run a single test out of a spec you can do the following:

rspec path/to/spec:<line number>

where -line number- is a line number that contains part of your test. For example, if you had a spec like:

1: 
2: it "should be awesome" do
3:   foo = 3
4:   foo.should eq(3)
5: end
6:

Let's say it's saved in spec/models/foo_spec.rb. Then you would run:

rspec spec/models/foo_spec.rb:2

and it would just run that one spec. In fact, that number could be anything from 2 to 5.

Hope this helps!

How to uncheck checkbox using jQuery Uniform library

First of all, checked can have a value of checked, or an empty string.

$("input:checkbox").uniform();

$('#check1').live('click', function() {
    $('#check2').attr('checked', 'checked').uniform();
});

Reverse the ordering of words in a string

In Java using an additional String (with StringBuilder):

public static final String reverseWordsWithAdditionalStorage(String string) {
    StringBuilder builder = new StringBuilder();

    char c = 0;
    int index = 0;
    int last = string.length();
    int length = string.length()-1;
    StringBuilder temp = new StringBuilder();
    for (int i=length; i>=0; i--) {
        c = string.charAt(i);
        if (c == SPACE || i==0) {
            index = (i==0)?0:i+1;
            temp.append(string.substring(index, last));
            if (index!=0) temp.append(c);
            builder.append(temp);
            temp.delete(0, temp.length());
            last = i;
        }
    }

    return builder.toString();
}

In Java in-place:

public static final String reverseWordsInPlace(String string) {
    char[] chars = string.toCharArray();

    int lengthI = 0;
    int lastI = 0;
    int lengthJ = 0;
    int lastJ = chars.length-1;

    int i = 0;
    char iChar = 0;
    char jChar = 0;
    while (i<chars.length && i<=lastJ) {
        iChar = chars[i];
        if (iChar == SPACE) {
            lengthI = i-lastI;
            for (int j=lastJ; j>=i; j--) {
                jChar = chars[j];
                if (jChar == SPACE) {
                    lengthJ = lastJ-j;
                    swapWords(lastI, i-1, j+1, lastJ, chars);
                    lastJ = lastJ-lengthI-1;
                    break;
                }
            }
            lastI = lastI+lengthJ+1;
            i = lastI;
        } else {
            i++;
        }
    }

    return String.valueOf(chars);
}

private static final void swapWords(int startA, int endA, int startB, int endB, char[] array) {
    int lengthA = endA-startA+1;
    int lengthB = endB-startB+1;

    int length = lengthA;
    if (lengthA>lengthB) length = lengthB;

    int indexA = 0;
    int indexB = 0;
    char c = 0;
    for (int i=0; i<length; i++) {
        indexA = startA+i;
        indexB = startB+i;

        c = array[indexB];
        array[indexB] = array[indexA];
        array[indexA] = c;
    }

    if (lengthB>lengthA) {
        length = lengthB-lengthA;
        int end = 0;
        for (int i=0; i<length; i++) {
            end = endB-((length-1)-i);
            c = array[end];
            shiftRight(endA+i,end,array);
            array[endA+1+i] = c;
        }
    } else if (lengthA>lengthB) {
        length = lengthA-lengthB;
        for (int i=0; i<length; i++) {
            c = array[endA];
            shiftLeft(endA,endB,array);
            array[endB+i] = c;
        }
    }
}

private static final void shiftRight(int start, int end, char[] array) {
    for (int i=end; i>start; i--) {
        array[i] = array[i-1];
    }
}

private static final void shiftLeft(int start, int end, char[] array) {
    for (int i=start; i<end; i++) {
        array[i] = array[i+1];
    }
}

Back button and refreshing previous activity

I think onRestart() works better for this.

@Override
public void onRestart() { 
    super.onRestart();
    //When BACK BUTTON is pressed, the activity on the stack is restarted
    //Do what you want on the refresh procedure here
}

You could code what you want to do when the Activity is restarted (called again from the event 'back button pressed') inside onRestart().

For example, if you want to do the same thing you do in onCreate(), paste the code in onRestart() (eg. reconstructing the UI with the updated values).

"make_sock: could not bind to address [::]:443" when restarting apache (installing trac and mod_wsgi)

You guys are going to laugh at this. I had an extra Listen 443 in ports.conf that shouldn't have been there. Removing that solved this.

JAVA_HOME does not point to the JDK

I had a similar problem and it turned out the issue was having both versions 6 & 7 of OpenJDK. The answer comes from r-senior on ubuntu forums (http://ubuntuforums.org/showthread.php?t=1977619) --- just uninstall version 6:

sudo apt-get remove openjdk-6-*

make sure that JAVA_HOME and CLASSPATH aren't set to anything since that isn't actually the problem.

Rails filtering array of objects by attribute value

I'd go about this slightly differently. Structure your query to retrieve only what you need and split from there.

So make your query the following:

#                                vv or Job.find(1) vv
attachments = Attachment.where(job_id: @job.id, file_type: ["logo", "image"])
# or 
Job.includes(:attachments).where(id: your_job_id, attachments: { file_type: ["logo", "image"] })

And then partition the data:

@logos, @images = attachments.partition { |attachment| attachment.file_type == "logo" }

That will get the data you're after in a neat and efficient manner.

Install tkinter for Python

for python3 user, install python3-tk package by following command sudo apt-get install python3-tk

Using Math.round to round to one decimal place?

A neat alternative that is much more readable in my opinion, however, arguably a tad less efficient due to the conversions between double and String:

double num = 540.512;
double sum = 1978.8;

// NOTE: This does take care of rounding
String str = String.format("%.1f", (num/sum) * 100.0); 

If you want the answer as a double, you could of course convert it back:

double ans = Double.parseDouble(str);

Find something in column A then show the value of B for that row in Excel 2010

I figured out such data design:

Main sheet: Column A: Pump codes (numbers)

Column B: formula showing a corresponding row in sheet 'Ruhrpumpen'

=ROW(Pump_codes)+MATCH(A2;Ruhrpumpen!$I$5:$I$100;0)

Formulae have ";" instead of ",", it should be also German notation. If not, pleace replace.

Column C: formula showing data in 'Ruhrpumpen' column A from a row found by formula in col B

=INDIRECT("Ruhrpumpen!A"&$B2)

Column D: formula showing data in 'Ruhrpumpen' column B from a row found by formula in col B:

=INDIRECT("Ruhrpumpen!B"&$B2)

Sheet 'Ruhrpumpen':

Column A: some data about a certain pump

Column B: some more data

Column I: pump codes. Beginning of the list includes defined name 'Pump_codes' used by the formula in column B of the main sheet.

Spreadsheet example: http://www.bumpclub.ee/~jyri_r/Excel/Data_from_other_sheet_by_code_row.xls

jQuery each loop in table row

Use immediate children selector >:

$('#tblOne > tbody  > tr')

Description: Selects all direct child elements specified by "child" of elements specified by "parent".

Compile to a stand-alone executable (.exe) in Visual Studio

If I understand you correctly, yes you can, but not under Visual Studio (from what I know). To force the compiler to generate a real, standalone executable (which means you use C# like any other language) you use the program mkbundle (shipped with Mono). This will compile your C# app into a real, no dependency executable.

There is a lot of misconceptions about this around the internet. It does not defeat the purpose of the .net framework like some people state, because how can you lose future features of the .net framework if you havent used these features to begin with? And when you ship updates to your app, it's not exactly hard work to run it through the mkbundle processor before building your installer. There is also a speed benefit involved making your app run at native speed (because now it IS native).

In C++ or Delphi you have the same system, but without the middle MSIL layer. So if you use a namespace or sourcefile (called a unit under Delphi), then it's compiled and included in your final binary. So your final binary will be larger (Read: "Normal" size for a real app). The same goes for the parts of the framework you use in .net, these are also included in your app. However, smart linking does shave a conciderable amount.

Hope it helps!

How to use executables from a package installed locally in node_modules?

If you want your PATH variable to correctly update based on your current working directory, add this to the end of your .bashrc-equivalent (or after anything that defines PATH):

__OLD_PATH=$PATH
function updatePATHForNPM() {
  export PATH=$(npm bin):$__OLD_PATH
}

function node-mode() {
  PROMPT_COMMAND=updatePATHForNPM
}

function node-mode-off() {
  unset PROMPT_COMMAND
  PATH=$__OLD_PATH
}

# Uncomment to enable node-mode by default:
# node-mode

This may add a short delay every time the bash prompt gets rendered (depending on the size of your project, most likely), so it's disabled by default.

You can enable and disable it within your terminal by running node-mode and node-mode-off, respectively.

jQuery Validate - Enable validation for hidden fields

This worked for me, within an ASP.NET MVC3 site where I'd left the framework to setup unobtrusive validation etc., in case it's useful to anyone:

$("form").data("validator").settings.ignore = "";

Where/how can I download (and install) the Microsoft.Jet.OLEDB.4.0 for Windows 8, 64 bit?

On modern Windows this driver isn't available by default anymore, but you can download as Microsoft Access Database Engine 2010 Redistributable on the MS site. If your app is 32 bits be sure to download and install the 32 bits variant because to my knowledge the 32 and 64 bit variant cannot coexist.

Depending on how your app locates its db driver, that might be all that's needed. However, if you use an UDL file there's one extra step - you need to edit that file. Unfortunately, on a 64bits machine the wizard used to edit UDL files is 64 bits by default, it won't see the JET driver and just slap whatever driver it finds first in the UDL file. There are 2 ways to solve this issue:

  1. start the 32 bits UDL wizard like this: C:\Windows\syswow64\rundll32.exe "C:\Program Files (x86)\Common Files\System\Ole DB\oledb32.dll",OpenDSLFile C:\path\to\your.udl. Note that I could use this technique on a Win7 64 Pro, but it didn't work on a Server 2008R2 (could be my mistake, just mentioning)
  2. open the UDL file in Notepad or another text editor, it should more or less have this format:

[oledb] ; Everything after this line is an OLE DB initstring Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Path\To\The\database.mdb;Persist Security Info=False

That should allow your app to start correctly.

How to force browser to download file?

Set content-type and other headers before you write the file out. For small files the content is buffered, and the browser gets the headers first. For big ones the data come first.

Replacing Numpy elements if condition is met

You can create your mask array in one step like this

mask_data = input_mask_data < 3

This creates a boolean array which can then be used as a pixel mask. Note that we haven't changed the input array (as in your code) but have created a new array to hold the mask data - I would recommend doing it this way.

>>> input_mask_data = np.random.randint(0, 5, (3, 4))
>>> input_mask_data
array([[1, 3, 4, 0],
       [4, 1, 2, 2],
       [1, 2, 3, 0]])
>>> mask_data = input_mask_data < 3
>>> mask_data
array([[ True, False, False,  True],
       [False,  True,  True,  True],
       [ True,  True, False,  True]], dtype=bool)
>>> 

Android WebView Cookie Problem

I have faced same problem and It will resolve this issue in all android versions

private void setCookie() {
    try {
        CookieSyncManager.createInstance(context);
        CookieManager cookieManager = CookieManager.getInstance();
        cookieManager.setAcceptCookie(true);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            cookieManager.setCookie(Constant.BASE_URL, getCookie(), value -> {
                String cookie = cookieManager.getCookie(Constant.BASE_URL);
                CookieManager.getInstance().flush();
                CustomLog.d("cookie", "cookie ------>" + cookie);
                setupWebView();
            });
        } else {
            cookieManager.setCookie(webUrl, getCookie());
            new Handler().postDelayed(this::setupWebView, 700);
            CookieSyncManager.getInstance().sync();
        }

    } catch (Exception e) {
        CustomLog.e(e);
    }
}

Java: convert List<String> to a String

All the references to Apache Commons are fine (and that is what most people use) but I think the Guava equivalent, Joiner, has a much nicer API.

You can do the simple join case with

Joiner.on(" and ").join(names)

but also easily deal with nulls:

Joiner.on(" and ").skipNulls().join(names);

or

Joiner.on(" and ").useForNull("[unknown]").join(names);

and (useful enough as far as I'm concerned to use it in preference to commons-lang), the ability to deal with Maps:

Map<String, Integer> ages = .....;
String foo = Joiner.on(", ").withKeyValueSeparator(" is ").join(ages);
// Outputs:
// Bill is 25, Joe is 30, Betty is 35

which is extremely useful for debugging etc.

Detecting when the 'back' button is pressed on a navbar

This works for me in iOS 9.3.x with Swift:

override func didMoveToParentViewController(parent: UIViewController?) {
    super.didMoveToParentViewController(parent)

    if parent == self.navigationController?.parentViewController {
        print("Back tapped")
    }
}

Unlike other solutions here, this doesn't seem to trigger unexpectedly.

xlrd.biffh.XLRDError: Excel xlsx file; not supported

The previous version, xlrd 1.2.0, may appear to work, but it could also expose you to potential security vulnerabilities. With that warning out of the way, if you still want to give it a go, type the following command:

pip install xlrd==1.2.0

HTTP Error 404.3-Not Found in IIS 7.5

In my case, along with Mekanik's suggestions, I was receiving this error in Windows Server 2012 and I had to tick "HTTP Activation" in "Add Role Services".

HTML5 Number Input - Always show 2 decimal places

I know this is an old question, but it seems to me that none of these answers seem to answer the question being asked so hopefully this will help someone in the future.

Yes you can always show 2 decimal places, but unfortunately it can't be done with the element attributes alone, you have to use JavaScript.

I should point out this isn't ideal for large numbers as it will always force the trailing zeros, so the user will have to move the cursor back instead of deleting characters to set a value greater than 9.99

_x000D_
_x000D_
//Use keyup to capture user input & mouse up to catch when user is changing the value with the arrows_x000D_
    $('.trailing-decimal-input').on('keyup mouseup', function (e) {_x000D_
_x000D_
        // on keyup check for backspace & delete, to allow user to clear the input as required_x000D_
        var key = e.keyCode || e.charCode;_x000D_
        if (key == 8 || key == 46) {_x000D_
            return false;_x000D_
        };_x000D_
_x000D_
        // get the current input value_x000D_
        let correctValue = $(this).val().toString();_x000D_
_x000D_
         //if there is no decimal places add trailing zeros_x000D_
        if (correctValue.indexOf('.') === -1) {_x000D_
            correctValue += '.00';_x000D_
        }_x000D_
_x000D_
        else {_x000D_
_x000D_
            //if there is only one number after the decimal add a trailing zero_x000D_
            if (correctValue.toString().split(".")[1].length === 1) {_x000D_
                correctValue += '0'_x000D_
            }_x000D_
_x000D_
            //if there is more than 2 decimal places round backdown to 2_x000D_
            if (correctValue.toString().split(".")[1].length > 2) {_x000D_
                correctValue = parseFloat($(this).val()).toFixed(2).toString();_x000D_
            }_x000D_
        }_x000D_
_x000D_
        //update the value of the input with our conditions_x000D_
        $(this).val(correctValue);_x000D_
    });
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<input id="my-number-input" class="form-control trailing-decimal-input" type="number" min="0.01" step="0.01" value="0.00" />
_x000D_
_x000D_
_x000D_

SQL join: selecting the last records in a one-to-many relationship

You haven't specified the database. If it is one that allows analytical functions it may be faster to use this approach than the GROUP BY one(definitely faster in Oracle, most likely faster in the late SQL Server editions, don't know about others).

Syntax in SQL Server would be:

SELECT c.*, p.*
FROM customer c INNER JOIN 
     (SELECT RANK() OVER (PARTITION BY customer_id ORDER BY date DESC) r, *
             FROM purchase) p
ON (c.id = p.customer_id)
WHERE p.r = 1

Replace a string in a file with nodejs

<p>Please click in the following {{link}} to verify the account</p>


function renderHTML(templatePath: string, object) {
    const template = fileSystem.readFileSync(path.join(Application.staticDirectory, templatePath + '.html'), 'utf8');
    return template.match(/\{{(.*?)\}}/ig).reduce((acc, binding) => {
        const property = binding.substring(2, binding.length - 2);
        return `${acc}${template.replace(/\{{(.*?)\}}/, object[property])}`;
    }, '');
}
renderHTML(templateName, { link: 'SomeLink' })

for sure you can improve the reading template function to read as stream and compose the bytes by line to make it more efficient

UIView with rounded corners and drop shadow?

You need add masksToBounds = true for combined between corderRadius shadowRadius.

button.layer.masksToBounds = false;

What is the best way to remove accents (normalize) in a Python unicode string?

This handles not only accents, but also "strokes" (as in ø etc.):

import unicodedata as ud

def rmdiacritics(char):
    '''
    Return the base character of char, by "removing" any
    diacritics like accents or curls and strokes and the like.
    '''
    desc = ud.name(char)
    cutoff = desc.find(' WITH ')
    if cutoff != -1:
        desc = desc[:cutoff]
        try:
            char = ud.lookup(desc)
        except KeyError:
            pass  # removing "WITH ..." produced an invalid name
    return char

This is the most elegant way I can think of (and it has been mentioned by alexis in a comment on this page), although I don't think it is very elegant indeed. In fact, it's more of a hack, as pointed out in comments, since Unicode names are – really just names, they give no guarantee to be consistent or anything.

There are still special letters that are not handled by this, such as turned and inverted letters, since their unicode name does not contain 'WITH'. It depends on what you want to do anyway. I sometimes needed accent stripping for achieving dictionary sort order.

EDIT NOTE:

Incorporated suggestions from the comments (handling lookup errors, Python-3 code).

Get checkbox value in jQuery

//By each()
var testval = [];
 $('.hobbies_class:checked').each(function() {
   testval.push($(this).val());
 });


//by map()
var testval = $('input:checkbox:checked.hobbies_class').map(function(){
return this.value; }).get().join(",");

 //HTML Code

 <input type="checkbox" value="cricket" name="hobbies[]"  class="hobbies_class">Cricket 
  <input type="checkbox" value="hockey" name="hobbies[]" class="hobbies_class">Hockey

Example
Demo

Cannot install packages using node package manager in Ubuntu

you can create a link ln -s nodejs node in /usr/bin hope this solves your problem.

How do I connect to a MySQL Database in Python?

Stop Using MySQLDb if you want to avoid installing mysql headers just to access mysql from python.

Use pymysql. It does all of what MySQLDb does, but it was implemented purely in Python with NO External Dependencies. This makes the installation process on all operating systems consistent and easy. pymysql is a drop in replacement for MySQLDb and IMHO there is no reason to ever use MySQLDb for anything... EVER! - PTSD from installing MySQLDb on Mac OSX and *Nix systems, but that's just me.

Installation

pip install pymysql

That's it... you are ready to play.

Example usage from pymysql Github repo

import pymysql.cursors
import pymysql

# Connect to the database
connection = pymysql.connect(host='localhost',
                             user='user',
                             password='passwd',
                             db='db',
                             charset='utf8mb4',
                             cursorclass=pymysql.cursors.DictCursor)

try:
    with connection.cursor() as cursor:
        # Create a new record
        sql = "INSERT INTO `users` (`email`, `password`) VALUES (%s, %s)"
        cursor.execute(sql, ('[email protected]', 'very-secret'))

    # connection is not autocommit by default. So you must commit to save
    # your changes.
    connection.commit()

    with connection.cursor() as cursor:
        # Read a single record
        sql = "SELECT `id`, `password` FROM `users` WHERE `email`=%s"
        cursor.execute(sql, ('[email protected]',))
        result = cursor.fetchone()
        print(result)
finally:
    connection.close()

ALSO - Replace MySQLdb in existing code quickly and transparently

If you have existing code that uses MySQLdb, you can easily replace it with pymysql using this simple process:

# import MySQLdb << Remove this line and replace with:
import pymysql
pymysql.install_as_MySQLdb()

All subsequent references to MySQLdb will use pymysql transparently.

Is there a way to link someone to a YouTube Video in HD 1080p quality?

To link to a YouTube video so it plays in HD by default, use the following URL:

https://www.youtube.com/v/VIDEOID?version=3&vq=hd1080

Change VIDEOID to the YouTube video ID that you want to link to. When someone follows the link, it will display the highest-resolution available (up to 1080p) in full-screen mode. Unfortunately, vq=hd1080 does not work on the normal YouTube site (with comments and related videos).

Get the _id of inserted document in Mongo database in NodeJS

Another way to do it in async function :

const express = require('express')
const path = require('path')
const db = require(path.join(__dirname, '../database/config')).db;
const router = express.Router()

// Create.R.U.D
router.post('/new-order', async function (req, res, next) {

    // security check
    if (Object.keys(req.body).length === 0) {
        res.status(404).send({
            msg: "Error",
            code: 404
        });
        return;
    }

    try {

        // operations
        let orderNumber = await db.collection('orders').countDocuments()
        let number = orderNumber + 1
        let order = {
            number: number,
            customer: req.body.customer,
            products: req.body.products,
            totalProducts: req.body.totalProducts,
            totalCost: req.body.totalCost,
            type: req.body.type,
            time: req.body.time,
            date: req.body.date,
            timeStamp: Date.now(),

        }

        if (req.body.direction) {
            order.direction = req.body.direction
        }

        if (req.body.specialRequests) {
            order.specialRequests = req.body.specialRequests
        }

        // Here newOrder will store some informations in result of this process.
        // You can find the inserted id and some informations there too.
        
        let newOrder = await db.collection('orders').insertOne({...order})

        if (newOrder) {

            // MARK: Server response
            res.status(201).send({
                msg: `Order N°${number} created : id[${newOrder.insertedId}]`,
                code: 201
            });

        } else {

            // MARK: Server response
            res.status(404).send({
                msg: `Order N°${number} not created`,
                code: 404
            });

        }

    } catch (e) {
        print(e)
        return
    }

})

// C.Read.U.D


// C.R.Update.D


// C.R.U.Delete



module.exports = router;

Unable to call the built in mb_internal_encoding method?

If someone is having trouble with installing php-mbstring package in ubuntu do following sudo apt-get install libapache2-mod-php5

How to align LinearLayout at the center of its parent?

add layout_gravity="center" or "center_horizontal" to the parent layout.

On a side note, your LinearLayout inside your TableRow seems un-necessary, as a TableRow is already an horizontal LinearLayout.

Mongodb find() query : return only unique values (no duplicates)

I think you can use db.collection.distinct(fields,query)

You will be able to get the distinct values in your case for NetworkID.

It should be something like this :

Db.collection.distinct('NetworkID')

Bootstrap 3, 4 and 5 .container-fluid with grid adding unwanted padding

In the new alpha versions they've introduced utility spacing classes. The structure can then be tweaked if you use them in a clever way.

Spacing utility classes

<div class="container-fluid">
    <div class="row">
        <div class="col-sm-4 col-md-3 pl-0">…</div>
        <div class="col-sm-4 col-md-3">…</div>
        <div class="col-sm-4 col-md-3">…</div>
        <div class="col-sm-4 col-md-3 pr-0">…</div>
    </div>
</div>

pl-0 and pr-0 will remove leading and trailing padding from the columns. One issue left is the embedded rows of a column, as they still have negative margin. In this case:

<div class="col-sm-12 col-md-6 pl-0">
    <div class="row ml-0">
</div>

Version differences

Also note the utility spacing classes were changed since version 4.0.0-alpha.4. Before they were separated by 2 dashes e.g. => p-x-0 and p-l-0 and so on ...

To stay on topic for the version 3: This is what I use on Bootstrap 3 projects and include the compass setup, for this particular spacing utility, into bootstrap-sass (version 3) or bootstrap (version 4.0.0-alpha.3) with double dashes or bootstrap (version 4.0.0-alpha.4 and up) with single dashes.

Also, latest version(s) go up 'till 5 times a ratio (ex: pt-5 padding-top 5) instead of only 3.


Compass

$grid-breakpoints: (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px) !default;

@import "../scss/mixins/breakpoints"; // media-breakpoint-up, breakpoint-infix
@import "../scss/utilities/_spacing.scss";

CSS output

You can ofcourse always copy/paste the padding spacing classes only from a generated css file.

.p-0 { padding: 0 !important; }
.pt-0 { padding-top: 0 !important; }
.pr-0 { padding-right: 0 !important; }
.pb-0 { padding-bottom: 0 !important; }
.pl-0 { padding-left: 0 !important; }
.px-0 { padding-right: 0 !important; padding-left: 0 !important; }
.py-0 { padding-top: 0 !important; padding-bottom: 0 !important; }
.p-1 { padding: 0.25rem !important; }
.pt-1 { padding-top: 0.25rem !important; }
.pr-1 { padding-right: 0.25rem !important; }
.pb-1 { padding-bottom: 0.25rem !important; }
.pl-1 { padding-left: 0.25rem !important; }
.px-1 { padding-right: 0.25rem !important; padding-left: 0.25rem !important; }
.py-1 { padding-top: 0.25rem !important; padding-bottom: 0.25rem !important; }
.p-2 { padding: 0.5rem !important; }
.pt-2 { padding-top: 0.5rem !important; }
.pr-2 { padding-right: 0.5rem !important; }
.pb-2 { padding-bottom: 0.5rem !important; }
.pl-2 { padding-left: 0.5rem !important; }
.px-2 { padding-right: 0.5rem !important; padding-left: 0.5rem !important; }
.py-2 { padding-top: 0.5rem !important; padding-bottom: 0.5rem !important; }
.p-3 { padding: 1rem !important; }
.pt-3 { padding-top: 1rem !important; }
.pr-3 { padding-right: 1rem !important; }
.pb-3 { padding-bottom: 1rem !important; }
.pl-3 { padding-left: 1rem !important; }
.px-3 { padding-right: 1rem !important; padding-left: 1rem !important; }
.py-3 { padding-top: 1rem !important; padding-bottom: 1rem !important; }
.p-4 { padding: 1.5rem !important; }
.pt-4 { padding-top: 1.5rem !important; }
.pr-4 { padding-right: 1.5rem !important; }
.pb-4 { padding-bottom: 1.5rem !important; }
.pl-4 { padding-left: 1.5rem !important; }
.px-4 { padding-right: 1.5rem !important; padding-left: 1.5rem !important; }
.py-4 { padding-top: 1.5rem !important; padding-bottom: 1.5rem !important; }
.p-5 { padding: 3rem !important; }
.pt-5 { padding-top: 3rem !important; }
.pr-5 { padding-right: 3rem !important; }
.pb-5 { padding-bottom: 3rem !important; }
.pl-5 { padding-left: 3rem !important; }
.px-5 { padding-right: 3rem !important; padding-left: 3rem !important; }
.py-5 { padding-top: 3rem !important; padding-bottom: 3rem !important; }

Convert character to Date in R

You may be overcomplicating things, is there any reason you need the stringr package?

 df <- data.frame(Date = c("10/9/2009 0:00:00", "10/15/2009 0:00:00"))
 as.Date(df$Date, "%m/%d/%Y %H:%M:%S")

[1] "2009-10-09" "2009-10-15"

More generally and if you need the time component as well, use strptime:

strptime(df$Date, "%m/%d/%Y %H:%M:%S")

I'm guessing at what your actual data might look at from the partial results you give.

Unstage a deleted file in git

If it has been staged and committed, then the following will reset the file:

git reset COMMIT_HASH file_path
git checkout COMMIT_HASH file_path
git add file_path

This will work for a deletion that occurred several commits previous.