Programs & Examples On #Rvm

RVM (Ruby Version Manager) is a command line tool which allows users to install, manage and work with multiple Ruby environments from interpreters to sets of gems easily in the various Unix-like systems (such as Linux and Mac OS X).

How to Uninstall RVM?

It’s easy; just do the following:

rvm implode


rm -rf ~/.rvm

And don’t forget to remove the script calls in the following files:

  • ~/.bashrc
  • ~/.bash_profile
  • ~/.profile

And maybe others depending on whatever shell you’re using.

Which Ruby version am I really running?

The ruby version 1.8.7 seems to be your system ruby.

Normally you can choose the ruby version you'd like, if you are using rvm with following. Simple change into your directory in a new terminal and type in:

rvm use 2.0.0

You can find more details about rvm here: Open the website and scroll down, you will see a few helpful links. "Setting up default rubies" for example could help you.

Update: To set the ruby as default:

rvm use 2.0.0 --default

How to resolve "gpg: command not found" error during RVM installation?

On my clean macOS 10.15.7, I needed to brew link gnupg && brew unlink gnupg first and then used Ashish's answer to use gpg instead of gpg2. I also had to chown a few directories. before the un/link.

RVM is not a function, selecting rubies with 'rvm use ...' will not work

If you don't want that every time you open a terminal, do the suggestion above again, just add

source ~/.rvm/scripts/rvm

at the end of ~/.bashrc

How to remove RVM (Ruby Version Manager) from my system

I am running Ubuntu 19.04 and followed all the instructions above and then some. Finally, what worked for me was to run

sudo apt autoremove rvm

and now when I try and reinstall RVM it's actually gone. RVM is invasive, to say the least.

rmagick gem install "Can't find Magick-config"

Things change...maybe this will help someone else:

sudo apt-get install libmagick9-dev used to work. But with a later version of imagemagick I needed:

sudo apt-get install graphicsmagick-libmagick-dev-compat libmagickcore-dev libmagickwand-dev

Installed Ruby 1.9.3 with RVM but command line doesn't show ruby -v

  • Open Terminal.
  • Go to Edit -> Profile Preferences.
  • Select the Title & command Tab in the window opened.
  • Mark the checkbox Run command as login shell.
  • close the window and restart the Terminal.

Check this Official Linkenter image description here

How do I hide anchor text without hiding the anchor?

Wrap the text in a span and set visibility:hidden; Visibility hidden will hide the element but it will still take up the same space on the page (conversely display: none removes it from the page as well).

c# - How to get sum of the values from List?

Use Sum()

 List<string> foo = new List<string>();

 Console.Write(foo.Sum(x => Convert.ToInt32(x)));



Oracle insert from select into table with more columns

Just add in the '0' in your select.

INSERT INTO table_name (a,b,c,d)
       other_table.a AS a,
       other_table.b AS b,
       other_table.c AS c,
       '0' AS d
    FROM other_table

Get last 30 day records from today date in SQL Server

This Should Work Fine

SELECT * FROM product 
WHERE pdate BETWEEN datetime('now', '-30 days') AND datetime('now', 'localtime')

Syntax for async arrow function

You may also do:

 YourAsyncFunctionName = async (value) => {

    /* Code goes here */


error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup

if you have _tmain function in your projects you need to include <tchar.h>.

What can be the reasons of connection refused errors?

I had the same message with a totally different cause: the wsock32.dll was not found. The ::socket(PF_INET, SOCK_STREAM, 0); call kept returning an INVALID_SOCKET but the reason was that the winsock dll was not loaded.

In the end I launched Sysinternals' process monitor and noticed that it searched for the dll 'everywhere' but didn't find it.

Silent failures are great!

How to change line width in IntelliJ (from 120 character)

IntelliJ IDEA 2018

File > Settings... > Editor > Code Style > Hard wrap at

Code Style > Hard wrap at

IntelliJ IDEA 2016 & 2017

File > Settings... > Editor > Code Style > Right margin (columns):

File > Settings

Editor > Code Style > Right margin

How to access host port from docker container

We found that a simpler solution to all this networking junk is to just use the domain socket for the service. If you're trying to connect to the host anyway, just mount the socket as a volume, and you're on your way. For postgresql, this was as simple as:

docker run -v /var/run/postgresql:/var/run/postgresql

Then we just set up our database connection to use the socket instead of network. Literally that easy.

How to sum a variable by group

using cast instead of recast (note 'Frequency' is now 'value')

df  <- data.frame(Category = c("First","First","First","Second","Third","Third","Second")
                  , value = c(10,15,5,2,14,20,3))


result<-cast(df, Category ~ . ,fun.aggregate=sum)

to get:

Category (all)
First     30
Second    5
Third     34

Can I run javascript before the whole page is loaded?

Not only can you, but you have to make a special effort not to if you don't want to. :-)

When the browser encounters a classic script tag when parsing the HTML, it stops parsing and hands over to the JavaScript interpreter, which runs the script. The parser doesn't continue until the script execution is complete (because the script might do document.write calls to output markup that the parser should handle).

That's the default behavior, but you have a few options for delaying script execution:

  1. Use JavaScript modules. A type="module" script is deferred until the HTML has been fully parsed and the initial DOM created. This isn't the primary reason to use modules, but it's one of the reasons:

    <script type="module" src="./my-code.js"></script>
    <!-- Or -->
    <script type="module">
    // Your code here

    The code will be fetched (if it's separate) and parsed in parallel with the HTML parsing, but won't be run until the HTML parsing is done. (If your module code is inline rather than in its own file, it is also deferred until HTML parsing is complete.)

    This wasn't available when I first wrote this answer in 2010, but here in 2020, all major modern browsers support modules natively, and if you need to support older browsers, you can use bundlers like Webpack and Rollup.js.

  2. Use the defer attribute on a classic script tag:

    <script defer src="./my-code.js"></script>

    As with the module, the code in my-code.js will be fetched and parsed in parallel with the HTML parsing, but won't be run until the HTML parsing is done. But, defer doesn't work with inline script content, only with external files referenced via src.

  3. I don't think it's what you want, but you can use the async attribute to tell the browser to fetch the JavaScript code in parallel with the HTML parsing, but then run it as soon as possible, even if the HTML parsing isn't complete. You can put it on a type="module" tag, or use it instead of defer on a classic script tag.

  4. Put the script tag at the end of the document, just prior to the closing </body> tag:

    <!doctype html>
    <!-- ... -->
    <!-- The document's HTML goes here -->
    <script type="module" src="./my-code.js"></script><!-- Or inline script -->

    That way, even though the code is run as soon as its encountered, all of the elements defined by the HTML above it exist and are ready to be used.

    It used to be that this caused an additional delay on some browsers because they wouldn't start fetching the code until the script tag was encountered, but modern browsers scan ahead and start prefetching. Still, this is very much the third choice at this point, both modules and defer are better options.

The spec has a useful diagram showing a raw script tag, defer, async, type="module", and type="module" async and the timing of when the JavaScript code is fetched and run:

enter image description here

Here's an example of the default behavior, a raw script tag:

.found {_x000D_
    color: green;_x000D_
<p>Paragraph 1</p>_x000D_
    if (typeof NodeList !== "undefined" && !NodeList.prototype.forEach) {_x000D_
        NodeList.prototype.forEach = Array.prototype.forEach;_x000D_
    document.querySelectorAll("p").forEach(p => {_x000D_
<p>Paragraph 2</p>

(See my answer here for details around that NodeList code.)

When you run that, you see "Paragraph 1" in green but "Paragraph 2" is black, because the script ran synchronously with the HTML parsing, and so it only found the first paragraph, not the second.

In contrast, here's a type="module" script:

.found {_x000D_
    color: green;_x000D_
<p>Paragraph 1</p>_x000D_
<script type="module">_x000D_
    document.querySelectorAll("p").forEach(p => {_x000D_
<p>Paragraph 2</p>

Notice how they're both green now; the code didn't run until HTML parsing was complete. That would also be true with a defer script with external content (but not inline content).

(There was no need for the NodeList check there because any modern browser supporting modules already has forEach on NodeList.)

In this modern world, there's no real value to the DOMContentLoaded event of the "ready" feature that PrototypeJS, jQuery, ExtJS, Dojo, and most others provided back in the day (and still provide); just use modules or defer. Even back in the day, there wasn't much reason for using them (and they were often used incorrectly, holding up page presentation while the entire jQuery library was loaded because the script was in the head instead of after the document), something some developers at Google flagged up early on. This was also part of the reason for the YUI recommendation to put scripts at the end of the body, again back in the day.

Add list to set?

Please notice the function set.update(). The documentation says:

Update a set with the union of itself and others.

For..In loops in JavaScript - key value pairs

If you can use ES6 natively or with Babel (js compiler) then you could do the following:

const test = {a: 1, b: 2, c: 3};_x000D_
for (const [key, value] of Object.entries(test)) {_x000D_
  console.log(key, value);_x000D_

Which will print out this output:

a 1
b 2
c 3

The Object.entries() method returns an array of a given object's own enumerable property [key, value] pairs, in the same order as that provided by a loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).

Hope it helps! =)

Any way to exit bash script, but not quitting the terminal

Also make sure to return with expected return value. Else if you use exit when you will encounter an exit it will exit from your base shell since source does not create another process (instance).

how to add jquery in laravel project

In Laravel 6 you can get it like this:

try {
    window.$ = window.jQuery = require('jquery');
} catch (e) {}

Error - is not marked as serializable

If you store an object in session state, that object must be serializable.


In order for the session to be serialized correctly, all objects the application stores as session attributes must declare the [Serializable] attribute. Additionally, if the object requires custom serialization methods, it must also implement the ISerializable interface.

How to dynamically create columns in datatable and assign values to it?

If you want to create dynamically/runtime data table in VB.Net then you should follow these steps as mentioned below :

  • Create Data table object.
  • Add columns into that data table object.
  • Add Rows with values into the object.

For eg.

Dim dt As New DataTable

dt.Columns.Add("Id", GetType(Integer))
dt.Columns.Add("FirstName", GetType(String))
dt.Columns.Add("LastName", GetType(String))

dt.Rows.Add(1, "Test", "data")
dt.Rows.Add(15, "Robert", "Wich")
dt.Rows.Add(18, "Merry", "Cylon")
dt.Rows.Add(30, "Tim", "Burst")

OpenCV in Android Studio

The below steps for using Android OpenCV sdk in Android Studio. This is a simplified version of this(1) SO answer.

  1. Download latest OpenCV sdk for Android from and decompress the zip file.
  2. Import OpenCV to Android Studio, From File -> New -> Import Module, choose sdk/java folder in the unzipped opencv archive.
  3. Update build.gradle under imported OpenCV module to update 4 fields to match your project build.gradle a) compileSdkVersion b) buildToolsVersion c) minSdkVersion and d) targetSdkVersion.
  4. Add module dependency by Application -> Module Settings, and select the Dependencies tab. Click + icon at bottom, choose Module Dependency and select the imported OpenCV module.
    • For Android Studio v1.2.2, to access to Module Settings : in the project view, right-click the dependent module -> Open Module Settings
  5. Copy libs folder under sdk/native to Android Studio under app/src/main.
  6. In Android Studio, rename the copied libs directory to jniLibs and we are done.

Step (6) is since Android studio expects native libs in app/src/main/jniLibs instead of older libs folder. For those new to Android OpenCV, don't miss below steps

  • include static{ System.loadLibrary("opencv_java"); } (Note: for OpenCV version 3 at this step you should instead load the library opencv_java3.)
  • For step(5), if you ignore any platform libs like x86, make sure your device/emulator is not on that platform.

OpenCV written is in C/C++. Java wrappers are

  1. Android OpenCV SDK - maintained Android Java wrapper. I suggest this one.
  2. OpenCV Java - maintained auto generated desktop Java wrapper.
  3. JavaCV - Popular Java wrapper maintained by independent developer(s). Not Android specific. This library might get out of sync with OpenCV newer versions.

How do I calculate someone's age based on a DateTime type birthday?

I think this problem can be solved with an easier way like this-

The class can be like-

using System;

namespace TSA
    class BirthDay
        double ageDay;
        public BirthDay(int day, int month, int year)
            DateTime birthDate = new DateTime(year, month, day);
            ageDay = (birthDate - DateTime.Now).TotalDays; //DateTime.UtcNow

        internal int GetAgeYear()
            return (int)Math.Truncate(ageDay / 365);

        internal int GetAgeMonth()
            return (int)Math.Truncate((ageDay % 365) / 30);

And calls can be like-

BirthDay b = new BirthDay(1,12,1990);
int year = b.GetAgeYear();
int month = b.GetAgeMonth();

How to BULK INSERT a file into a *temporary* table where the filename is a variable?

Sorry to dig up an old question but in case someone stumbles onto this thread and wants a quicker solution.

Bulk inserting a unknown width file with \n row terminators into a temp table that is created outside of the EXEC statement.


    DROP TABLE #BulkInsert

    Line    VARCHAR(MAX)


SELECT * FROM #BulkInsert

Further support that dynamic SQL within an EXEC statement has access to temp tables outside of the EXEC statement.!3/d41d8/19343


    DROP TABLE #BulkInsert

    Line    VARCHAR(MAX)

SET @SQL = 'SELECT * FROM #BulkInsert'

Further support, written for MSSQL2000

Example at the bottom of the link

DECLARE @cmd VARCHAR(1000), @ExecError INT
CREATE TABLE #ErrFile (ExecError INT)
SET @cmd = 'EXEC GetTableCount ' + 
'''pubs.dbo.authors''' + 
SET @ExecError = (SELECT * FROM #ErrFile)
SELECT @ExecError AS '@@ERROR'

How to disable or enable viewpager swiping in android

In my case, the simplified solution worked fine. The override method must be in your custom viewpager adapter to override TouchEvent listeners and make'em freeze;

public boolean onTouchEvent(MotionEvent event) {
    return this.enabled && super.onTouchEvent(event);


public boolean onInterceptTouchEvent(MotionEvent event) {
    return this.enabled && super.onInterceptTouchEvent(event);


Using psql how do I list extensions installed in a database?

This SQL query gives output similar to \dx:

SELECT e.extname AS "Name", e.extversion AS "Version", n.nspname AS "Schema", c.description AS "Description" 
FROM pg_catalog.pg_extension e 
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = e.extnamespace 
LEFT JOIN pg_catalog.pg_description c ON c.objoid = e.oid AND c.classoid = 'pg_catalog.pg_extension'::pg_catalog.regclass 

Thanks to

Pad a string with leading zeros so it's 3 characters long in SQL Server 2008

Here's a more general technique for left-padding to any desired width:

declare @x     int     = 123 -- value to be padded
declare @width int     = 25  -- desired width
declare @pad   char(1) = '0' -- pad character

select right_justified = replicate(
                           @pad ,
                       + convert(varchar(100),@x)

However, if you're dealing with negative values, and padding with leading zeroes, neither this, nor other suggested technique will work. You'll get something that looks like this:


[Probably not what you wanted]

So … you'll have to jump through some additional hoops Here's one approach that will properly format negative numbers:

declare @x     float   = -1.234
declare @width int     = 20
declare @pad   char(1) = '0'

select right_justified = stuff(
         convert(varchar(99),@x) ,                            -- source string (converted from numeric value)
         case when @x < 0 then 2 else 1 end ,                 -- insert position
         0 ,                                                  -- count of characters to remove from source string
         replicate(@pad,@width-len(convert(varchar(99),@x)) ) -- text to be inserted

One should note that the convert() calls should specify an [n]varchar of sufficient length to hold the converted result with truncation.

byte[] to hex string

I thought I should provide an answer. From my test this method is the fastest

public static class Helper
    public static string[] HexTbl = Enumerable.Range(0, 256).Select(v => v.ToString("X2")).ToArray();
    public static string ToHex(this IEnumerable<byte> array)
        StringBuilder s = new StringBuilder();
        foreach (var v in array)
        return s.ToString();
    public static string ToHex(this byte[] array)
        StringBuilder s = new StringBuilder(array.Length*2);
        foreach (var v in array)
        return s.ToString();

How to generate the JPA entity Metamodel?

Eclipse's JPA 2.0 support through Dali (which is included in "Eclipse IDE for JEE Developers") has its own metamodel generator integrated with Eclipse.

  1. Select your project in the Package Explorer
  2. Go to Properties -> JPA dialog
  3. Select source folder from Canonical metamodel (JPA 2.0) group
  4. Click Apply button to generate metamodel classes in the selected source folder

enter image description here

This should work on any JPA provider as the generated classes are standard.

Also see here.

How do I purge a linux mail box with huge number of emails?

If you're using cyrus/sasl/imap on your mailserver, then one fast and efficient way to purge everything in a mailbox that is older then number of days specified is to use cyrus/imap ipurge command. For example, here is an example removing everything (be carefull!!), older then 30 days from user vleo. Notice, that you must be logged in as cyrus (imap mail administrator) user:

[cyrus@mailserver ~]$ /usr/lib/cyrus-imapd/ipurge -f -d 30 user.vleo Working on user.vleo... total messages 4 total bytes 113183 Deleted messages 0 Deleted bytes 0 Remaining messages 4 Remaining bytes 113183

In Java, remove empty elements from a list of Strings

   private List cleanInputs(String[] inputArray) {
        List<String> result = new ArrayList<String>(inputArray.length);
        for (String input : inputArray) {
            if (input != null) {
                String str = input.trim();
                if (!str.isEmpty()) {
        return result;

Sorting dropdown alphabetically in AngularJS

Angular has an orderBy filter that can be used like this:

<select ng-model="selected" ng-options=" for f in friends | orderBy:'name'"></select>

See this fiddle for an example.

It's worth noting that if track by is being used it needs to appear after the orderBy filter, like this:

<select ng-model="selected" ng-options=" for f in friends | orderBy:'name' track by"></select>

How to return a resolved promise from an AngularJS Service using $q?

Return your promise , return deferred.promise.
It is the promise API that has the 'then' method.$q

Calling resolve does not return a promise it only signals the promise that the promise is resolved so it can execute the 'then' logic.

Basic pattern as follows, rinse and repeat

<!DOCTYPE html>

  <script data-require="angular.js@*" data-semver="1.3.0-beta.5" 
  <link rel="stylesheet" href="style.css" />
  <script src="script.js"></script>


<div ng-controller="test">
  <button ng-click="test()">test</button>
  var app = angular.module("app",[]);


    $scope.$test = function(){
      var deferred = $q.defer();
      return deferred.promise;




Adding text to a cell in Excel using VBA

You need to use Range and Value functions.
Range would be the cell where you want the text you want
Value would be the text that you want in that Cell

Range("A1").Value="whatever text"

Pass request headers in a jQuery AJAX GET call

As of jQuery 1.5, there is a headers hash you can pass in as follows:

    url: "/test",
    headers: {"X-Test-Header": "test-value"}


headers (added 1.5): A map of additional header key/value pairs to send along with the request. This setting is set before the beforeSend function is called; therefore, any values in the headers setting can be overwritten from within the beforeSend function.

"The POM for ... is missing, no dependency information available" even though it exists in Maven Repository

I had a similar problem quite recently. In my case:

  1. I downloaded an artifact from some less popular Maven repo

  2. This repo dissappeared over this year

  3. Now builds fail, even if I have this artifact and its pom.xml in my local repo


delete _remote.repositories file in your local repo, where this artifact resides. Now the project builds.

How do you convert an entire directory with ffmpeg?

A one-line bash script would be easy to do - replace *.avi with your filetype:

for i in *.avi; do ffmpeg -i "$i" -qscale 0 "$(basename "$i" .avi)".mov  ; done

Working with a List of Lists in Java

Something like this would work for reading:

String filename = "something.csv";
BufferedReader input = null;
List<List<String>> csvData = new ArrayList<List<String>>();
    input =  new BufferedReader(new FileReader(filename));
    String line = null;
    while (( line = input.readLine()) != null)
        String[] data = line.split(",");
catch (Exception ex)
    if(input != null)

Spring Boot and multiple external configuration files

UPDATE: As the behaviour of spring.config.location now overrides the default instead of adding to it. You need to use spring.config.additional-location to keep the defaults. This is a change in behaviour from 1.x to 2.x

When using Spring Boot the properties are loaded in the following order (see Externalized Configuration in the Spring Boot reference guide).

  1. Command line arguments.
  2. Java System properties (System.getProperties()).
  3. OS environment variables.
  4. JNDI attributes from java:comp/env
  5. A RandomValuePropertySource that only has properties in random.*.
  6. Application properties outside of your packaged jar ( including YAML and profile variants).
  7. Application properties packaged inside your jar ( including YAML and profile variants).
  8. @PropertySource annotations on your @Configuration classes.
  9. Default properties (specified using SpringApplication.setDefaultProperties).

When resolving properties (i.e. @Value("${myprop}") resolving is done in the reverse order (so starting with 9).

To add different files you can use the spring.config.location properties which takes a comma separated list of property files or file location (directories).


The one above will add a directory which will be consulted for files.,

This will add the 2 properties file to the files that are loaded.

The default configuration files and locations are loaded before the additonally specified spring.config.location ones meaning that the latter will always override properties set in the earlier ones. (See also this section of the Spring Boot Reference Guide).

If spring.config.location contains directories (as opposed to files) they should end in / (and will be appended with the names generated from before being loaded). The default search path classpath:,classpath:/config,file:,file:config/ is always used, irrespective of the value of spring.config.location. In that way you can set up default values for your application in (or whatever other basename you choose with and override it at runtime with a different file, keeping the defaults.

How do I specify different Layouts in the ASP.NET MVC 3 razor ViewStart file?

You could put a _ViewStart.cshtml file inside the /Views/Public folder which would override the default one in the /Views folder and specify the desired layout:

    Layout = "~/Views/Shared/_PublicLayout.cshtml";

By analogy you could put another _ViewStart.cshtml file inside the /Views/Staff folder with:

    Layout = "~/Views/Shared/_StaffLayout.cshtml";

You could also specify which layout should be used when returning a view inside a controller action but that's per action:

return View("Index", "~/Views/Shared/_StaffLayout.cshtml", someViewModel);

Yet another possibility is a custom action filter which would override the layout. As you can see many possibilities to achieve this. Up to you to choose which one fits best in your scenario.


As requested in the comments section here's an example of an action filter which would choose a master page:

public class LayoutInjecterAttribute : ActionFilterAttribute
    private readonly string _masterName;
    public LayoutInjecterAttribute(string masterName)
        _masterName = masterName;

    public override void OnActionExecuted(ActionExecutedContext filterContext)
        var result = filterContext.Result as ViewResult;
        if (result != null)
            result.MasterName = _masterName;

and then decorate a controller or an action with this custom attribute specifying the layout you want:

public ActionResult Index()
    return View();

Get all child elements

Here is a code to get the child elements (In java):

String childTag = childElement.getTagName();
    return "/html[1]"+current;
WebElement parentElement = childElement.findElement(By.xpath("..")); 
List<WebElement> childrenElements = parentElement.findElements(By.xpath("*"));
int count = 0;
for(int i=0;i<childrenElements.size(); i++) 
    WebElement childrenElement = childrenElements.get(i);
    String childrenElementTag = childrenElement.getTagName();

Changing default startup directory for command prompt in Windows 7

This doesn't work for me. I've tried this both under Win7 64bit and Vista 32.

I'm using the below commandline to add this capability.

reg add "HKEY_CURRENT_USER\Software\Microsoft\Command Processor" /v AutoRun /t REG_SZ /d "IF x"%COMSPEC%"==x%CMDCMDLINE% (cd /D c:)"

How to get subarray from array?

Take a look at Array.slice(begin, end)

const ar  = [1, 2, 3, 4, 5];

// slice from 1..3 - add 1 as the end index is not included

const ar2 = ar.slice(1, 3 + 1);


IE9 JavaScript error: SCRIPT5007: Unable to get value of the property 'ui': object is null or undefined

I was also facing the same issue.

I was using the code below in .aspx page without writing authentication configuration in web.config file. After writing the settings in Web.config, I am able to run my code.

<% If Request.IsAuthenticated Then%>
<%end if%> 

Build Eclipse Java Project from Command Line

The normal apporoach works the other way around: You create your build based upon maven or ant and then use integrations for your IDE of choice so that you are independent from it, which is esp. important when you try to bring new team members up to speed or use a contious integration server for automated builds. I recommend to use maven and let it do the heavy lifting for you. Create a pom file and generate the eclipse project via mvn eclipse:eclipse. HTH

Get last key-value pair in PHP array

As the key is needed, the accepted solution doesn't work.


return array(key($array) => array_pop($array));

will return exactly as the example in the question.

Checking if a collection is null or empty in Groovy


I think now the best way to solve this issue is code above. It works since Groovy 1.8.1 Examples:

def lst1 = []
assert !lst1.find()

def lst2 = [null]
assert !lst2.find()

def lst3 = [null,2,null]
assert lst3.find()

def lst4 = [null,null,null]
assert !lst4.find()

def lst5 = [null, 0, 0.0, false, '', [], 42, 43]
assert lst5.find() == 42

def lst6 = null; 
assert !lst6.find()

Android M Permissions: onRequestPermissionsResult() not being called

for kotlin users, here my extension to check and validate permissions without override onRequestPermissionResult

 * @param permissionToValidate (request and check currently permission)
 * @return recursive boolean validation callback (no need OnRequestPermissionResult)
 * */
internal fun Activity.validatePermission(
    permissionToValidate: String,
    recursiveCall: (() -> Boolean) = { false }
): Boolean {
    val permission = ContextCompat.checkSelfPermission(

    if (permission != PackageManager.PERMISSION_GRANTED) {
        if (recursiveCall()) {
            return false

        return this.validatePermission(permissionToValidate) { true }

    return true


Java generating Strings with placeholders

StrSubstitutor from Apache Commons Lang may be used for string formatting with named placeholders:

</dependency> :

Substitutes variables within a string by values.

This class takes a piece of text and substitutes all the variables within it. The default definition of a variable is ${variableName}. The prefix and suffix can be changed via constructors and set methods.

Variable values are typically resolved from a map, but could also be resolved from system properties, or by supplying a custom variable resolver.


String template = "Hi ${name}! Your number is ${number}";

Map<String, String> data = new HashMap<String, String>();
data.put("name", "John");
data.put("number", "1");

String formattedString = StrSubstitutor.replace(template, data);

Youtube API Limitations

Apart from other answer There are calculator provided by Youtube to check your usage. It is good to identify your usage.

enter image description here

Importing a GitHub project into Eclipse

As mentioned in Alain Beauvois's answer, and now (Q4 2013) better explained in

Copy the URL from GitHub and select in Eclipse from the menu the

File ? Import ? Git ? Projects from Git

If the Git repo isn't cloned yet:

In> order to checkout a remote project, you will have to clone its repository first.
Open the Eclipse Import wizard (e.g. File => Import), select Git => Projects from Git and click Next.
Select “URI” and click Next.
Now you will have to enter the repository’s location and connection data. Entering the URI will automatically fill some fields. Complete any other required fields and hit Next. If you use GitHub, you can copy the URI from the web page.

Select all branches you wish to clone and hit Next again.

Hit the Clone… button to open another wizard for cloning Git repositories.

Original answer (July 2011)

First, if your "Working Directory" is C:\Users, that is odd, since it would mean you have cloned the GitHub repo directly within C:\Users (i.e. you have a .git directory in C:\Users)

Usually, you would clone a GitHub repo in "any directory of your choice\theGitHubRepoName".

As described in the EGit user Manual page:

In any case (unless you create a "bare" Repository, but that's not discussed here), the new Repository is essentially a folder on the local hard disk which contains the "working directory" and the metadata folder.
The metadata folder is a dedicated child folder named ".git" and often referred to as ".git-folder". It contains the actual repository (i.e. the Commits, the References, the logs and such).

The metadata folder is totally transparent to the Git client, while the working directory is used to expose the currently checked out Repository content as files for tools and editors.

Typically, if these files are to be used in Eclipse, they must be imported into the Eclipse workspace in one way or another. In order to do so, the easiest way would be to check in .project files from which the "Import Existing Projects" wizard can create the projects easily. Thus in most cases, the structure of a Repository containing Eclipse projects would look similar to something like this:

See also the Using EGit with Github section.

My working directory is now c:\users\projectname\.git

You should have the content of that repo checked out in c:\users\projectname (in other words, you should have more than just the .git).

So then I try to import the project using the eclipse "import" option.
When I try to import selecting the option "Use the new projects wizard", the source code is not imported.

That is normal.

If I import selecting the option "Import as general project" the source code is imported but the created project created by Eclipse is not a java project.

Again normal.

When selecting the option "Use the new projects wizard" and creating a new java project using the wizard should'nt the code be automatically imported ?

No, that would only create an empty project.
If that project is created in c:\users\projectname, you can then declare the eisting source directory in that project.
Since it is defined in the same working directory than the Git repo, that project should then appear as "versioned".

You could also use the "Import existing project" option, if your GitHub repo had versioned the .project and .classpath file, but that may not be the case here.

How can I force users to access my page over HTTPS instead of HTTP?

You shouldn't for security reasons. Especially if cookies are in play here. It leaves you wide open to cookie-based replay attacks.

Either way, you should use Apache control rules to tune it.

Then you can test for HTTPS being enabled and redirect as-needed where needed.

You should redirect to the pay page only using a FORM POST (no get), and accesses to the page without a POST should be directed back to the other pages. (This will catch the people just hot-jumping.)

Is a good place to start, apologies for not providing more. But you really should shove everything through SSL.

It's over-protective, but at least you have less worries.

What is parsing in terms that a new programmer would understand?

I'd explain parsing as the process of turning some kind of data into another kind of data.

In practice, for me this is almost always turning a string, or binary data, into a data structure inside my Program.

For example, turning

":Nick!User@Host PRIVMSG #channel :Hello!"

into (C)

struct irc_line {
    char *nick;
    char *user;
    char *host;
    char *command;
    char **arguments;
    char *message;
} sample = { "Nick", "User", "Host", "PRIVMSG", { "#channel" }, "Hello!" }

How do I get today's date in C# in mm/dd/yyyy format?


is culture specific.

It is best to stick with:


Jenkins restrict view of jobs per user

Think this is, what you are searching for: Allow access to specific projects for Users

Short description without screenshots:
Use Jenkins "Project-based Matrix Authorization Strategy" under "Manage Jenkins" => "Configure System". On the configuration page of each project, you now have "Enable project-based security". Now add each user you want to authorize.

Cannot find module '../build/Release/bson'] code: 'MODULE_NOT_FOUND' } js-bson: Failed to load c++ bson extension, using pure JS version

I realize this thread is 1 year + old, but it helped me, albeit with a different module.

I installed mongoose-post-findv0.0.2 and this issue started. To fix it, I used the suggestions and navigated to \node_modules\mongoose-post-find\node_modules\bson\ext and opened the index.js file.

The file starts off with a try catch block trying to require the correct bson version

try {
    // Load the precompiled win32 binary
    if(process.platform == "win32" && process.arch == "x64") {
      bson = require('./win32/x64/bson');  
    } else if(process.platform == "win32" && process.arch == "ia32") {
      bson = require('./win32/ia32/bson');  
    } else {
      bson = require('../build/Release/bson');  
} catch(err) {
    // Attempt to load the release bson version
    try {
        bson = require('../browser_build/bson');
    } catch (err) {
        console.error("js-bson: Failed to load c++ bson extension, using pure JS version");
        bson = require('../lib/bson/bson');

this is the corrected version. What was happening is it tried to load bson from ../build/Release/bson, couldn't find it and fell into the catch. There is tried to load bson again from ../build/Release/bson and of course failed. So I changes the path in the catch to look in ../browser_build/bson. This resolved the error.

I post this for completeness.

How to run a cron job on every Monday, Wednesday and Friday?

Have you tried the following expression ..?

0 19 * * 1,3,5

Stretch background image css?

Just paste this into your line of codes:

<meta http-equiv="X-UA-Compatible" content="IE=Edge" />

How can I change the Java Runtime Version on Windows (7)?

For Java applications, i.e. programs that are delivered (usually) as .jar files and started with java -jar xxx.jar or via a shortcut that does the same, the JRE that will be launched will be the first one found on the PATH.

If you installed a JRE or JDK, the likely places to find the .exes are below directories like C:\Program Files\JavaSoft\JRE\x.y.z. However, I've found some "out of the box" Windows installations to (also?) have copies of java.exe and javaw.exe in C:\winnt\system32 (NT and 2000) or C:\windows\system (Windows 95, 98). This is usually a pretty elderly version of Java: 1.3, maybe? You'll want to do java -version in a command window to check that you're not running some antiquated version of Java.

You can of course override the PATH setting or even do without it by explicitly stating the path to java.exe / javaw.exe in your command line or shortcut definition.

If you're running applets from the browser, or possibly also Java Web Start applications (they look like applications insofar as they have their own window, but you start them from the browser), the choice of JRE is determined by a set of registry settings:

Key: HKEY_LOCAL_MACHINE\Software\JavaSoft\Java Runtime Environment
Name: CurrentVersion
Value: (e.g.) 1.3

More registry keys are created using this scheme:

HKEY_LOCAL_MACHINE\Software\JavaSoft\Java Runtime Environment\1.3   
HKEY_LOCAL_MACHINE\Software\JavaSoft\Java Runtime Environment\1.3.1

i.e. one for the major and one including the minor version number. Each of these keys has values like these (examples shown):

JavaHome    : C:\program Files\JavaSoft\JRE\1.3.1
RuntimeLib  : C:\Program Files\JavaSoft\JRE\1.3.1\bin\hotspot\jvm.dll
MicroVersion: 1

... and your browser will look to these settings to determine which JRE to fire up.

Since Java versions are changing pretty frequently, there's now a "wizard" called the "Java Control Panel" for manually switching your browser's Java version. This works for IE, Firefox and probably others like Opera and Chrome as well: It's the 'Java' applet in Windows' System Settings app. You get to pick any one of the installed JREs. I believe that wizard fiddles with those registry entries.

If you're like me and have "uninstalled" old Java versions by simply wiping out directories, you'll find these "ghosts" among the choices too; so make sure the JRE you choose corresponds to an intact Java installation!

Some other answers are recommending setting the environment variable JAVA_HOME. This is meanwhile outdated advice. Sun came to realize, around Java 2, that this environment setting is

  1. unreliable, as users often set it incorrectly, and
  2. unnecessary, as it's easy enough for the runtime to find the Java library directories, knowing they're in a fixed path relative to the path from which java.exe or javaw.exe was launched.

There's hardly any modern Java software left that needs or respects the JAVA_HOME environment variable.

More Information:

...and some useful information on multi-version support:

How to load a tsv file into a Pandas DataFrame?

df = pd.read_csv('filename.csv', sep='\t', header=0)

You can load the tsv file directly into pandas data frame by specifying delimitor and header.

How to calculate rolling / moving average using NumPy / SciPy?

moving average

iterator method

  • reverse the array at i, and simply take the mean from i to n.

  • use list comprehension to generate mini arrays on the fly.

x = np.random.randint(10, size=20)

def moving_average(arr, n):
    return [ (arr[:i+1][::-1][:n]).mean() for i, ele in enumerate(arr) ]
d = 5

moving_average(x, d)

tensor convolution

moving_average = np.convolve(x, np.ones(d)/d, mode='valid')

How to make custom error pages work in ASP.NET MVC 4

I had everything set up, but still couldn't see proper error pages for status code 500 on our staging server, despite the fact everything worked fine on local development servers.

I found this blog post from Rick Strahl that helped me.

I needed to add Response.TrySkipIisCustomErrors = true; to my custom error handling code.

How do you handle a form change in jQuery?

You can do this:

$("form :input").change(function() {
  $(this).closest('form').data('changed', true);
$('#mybutton').click(function() {
  if($(this).closest('form').data('changed')) {
     //do something

This rigs a change event handler to inputs in the form, if any of them change it uses .data() to set a changed value to true, then we just check for that value on the click, this assumes that #mybutton is inside the form (if not just replace $(this).closest('form') with $('#myForm')), but you could make it even more generic, like this:

$('.checkChangedbutton').click(function() {
  if($(this).closest('form').data('changed')) {
     //do something

References: Updated

According to jQuery this is a filter to select all form controls.

The :input selector basically selects all form controls.

Should CSS always preceed Javascript?

Steve Souders has already given a definitive answer but...

I wonder whether there's an issue with both Sam's original test and Josh's repeat of it.

Both tests appear to have been performed on low latency connections where setting up the TCP connection will have a trivial cost.

How this affects the result of the test I'm not sure and I'd want to look at the waterfalls for the tests over a 'normal' latency connection but...

The first file downloaded should get the connection used for the html page, and the second file downloaded will get the new connection. (Flushing the early alters that dynamic, but it's not being done here)

In newer browsers the second TCP connection is opened speculatively so the connection overhead is reduced / goes away, in older browsers this isn't true and the second connection will have the overhead of being opened.

Quite how/if this affects the outcome of the tests I'm not sure.

Hamcrest compare collections

To complement @Joe's answer:

Hamcrest provides you with three main methods to match a list:

contains Checks for matching all the elements taking in count the order, if the list has more or less elements, it will fail

containsInAnyOrder Checks for matching all the elements and it doesn't matter the order, if the list has more or less elements, will fail

hasItems Checks just for the specified objects it doesn't matter if the list has more

hasItem Checks just for one object it doesn't matter if the list has more

All of them can receive a list of objects and use equals method for comparation or can be mixed with other matchers like @borjab mentioned:

assertThat(myList , contains(allOf(hasProperty("id", is(7L)), 
                                   hasProperty("name", is("testName1")),
                                   hasProperty("description", is("testDesc1"))),
                             allOf(hasProperty("id", is(11L)), 
                                   hasProperty("name", is("testName2")),
                                   hasProperty("description", is("testDesc2")))));

How to reject in async/await syntax?

Your best bet is to throw an Error wrapping the value, which results in a rejected promise with an Error wrapping the value:

} catch (error) {
    throw new Error(400);

You can also just throw the value, but then there's no stack trace information:

} catch (error) {
    throw 400;

Alternately, return a rejected promise with an Error wrapping the value, but it's not idiomatic:

} catch (error) {
    return Promise.reject(new Error(400));

(Or just return Promise.reject(400);, but again, then there's no context information.)

In your case, as you're using TypeScript and foo's return value is Promise<A>, you'd use this:

return Promise.reject<A>(400 /*or Error*/ );

In an async/await situation, that last is probably a bit of a semantic mis-match, but it does work.

If you throw an Error, that plays well with anything consuming your foo's result with await syntax:

try {
    await foo();
} catch (error) {
    // Here, `error` would be an `Error` (with stack trace, etc.).
    // Whereas if you used `throw 400`, it would just be `400`.

How to uninstall pip on OSX?

Since pip is a package, pip uninstall pip Will do it.
EDIT: If that does not work, try sudo -H pip uninstall pip.

How to get the separate digits of an int number?

Convert it to String and use String#toCharArray() or String#split().

String number = String.valueOf(someInt);

char[] digits1 = number.toCharArray();
// or:
String[] digits2 = number.split("(?<=.)");

In case you're already on Java 8 and you happen to want to do some aggregate operations on it afterwards, consider using String#chars() to get an IntStream out of it.

IntStream chars = number.chars();

Cannot deserialize the JSON array (e.g. [1,2,3]) into type ' ' because type requires JSON object (e.g. {"name":"value"}) to deserialize correctly

var objResponse1 = 


How to use a typescript enum value in an Angular2 ngSwitch statement

This's simple and works like a charm :) just declare your enum like this and you can use it on HTML template

  statusEnum: typeof StatusEnum = StatusEnum;

PSEXEC, access denied errors

I just solved an identical symptom, by creating the registry value HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\system\LocalAccountTokenFilterPolicy and setting it to 1. More details are available here.

How in node to split string by newline ('\n')?

Try splitting on a regex like /\r?\n/ to be usable by both Windows and UNIX systems.

> "a\nb\r\nc".split(/\r?\n/)
[ 'a', 'b', 'c' ]

Add hover text without javascript like we hover on a user's reputation

Use the title attribute, for example:

<div title="them's hoverin' words">hover me</div>


<span title="them's hoverin' words">hover me</span>

JavaScript chop/slice/trim off last character in string

In cases where you want to remove something that is close to the end of a string (in case of variable sized strings) you can combine slice() and substr().

I had a string with markup, dynamically built, with a list of anchor tags separated by comma. The string was something like:

var str = "<a>text 1,</a><a>text 2,</a><a>text 2.3,</a><a>text abc,</a>";

To remove the last comma I did the following:

str = str.slice(0, -5) + str.substr(-4);

Cannot implicitly convert type 'System.Collections.Generic.IEnumerable<AnonymousType#1>' to 'System.Collections.Generic.List<string>

If you want it to be List<string>, get rid of the anonymous type and add a .ToList() call:

List<string> list = (from char c in source
                     select c.ToString()).ToList();

Converting BitmapImage to Bitmap and vice versa

Here the async version.

public static Task<BitmapSource> ToBitmapSourceAsync(this Bitmap bitmap)
    return Task.Run(() =>
        using (System.IO.MemoryStream memory = new System.IO.MemoryStream())
            bitmap.Save(memory, ImageFormat.Png);
            memory.Position = 0;
            BitmapImage bitmapImage = new BitmapImage();
            bitmapImage.StreamSource = memory;
            bitmapImage.CacheOption = BitmapCacheOption.OnLoad;
            return bitmapImage as BitmapSource;


How can I convert a .py to .exe for Python?

Steps to convert .py to .exe in Python 3.6

  1. Install Python 3.6.
  2. Install cx_Freeze, (open your command prompt and type pip install cx_Freeze.
  3. Install idna, (open your command prompt and type pip install idna.
  4. Write a .py program named
  5. Create a new python file named on the current directory of your script.
  6. In the file, copy the code below and save it.
  7. With shift pressed right click on the same directory, so you are able to open a command prompt window.
  8. In the prompt, type python build
  9. If your script is error free, then there will be no problem on creating application.
  10. Check the newly created folder build. It has another folder in it. Within that folder you can find your application. Run it. Make yourself happy.

See the original script in my blog.

from cx_Freeze import setup, Executable

base = None    

executables = [Executable("", base=base)]

packages = ["idna"]
options = {
    'build_exe': {    

    name = "<any name>",
    options = options,
    version = "<any number>",
    description = '<any description>',
    executables = executables


  • be sure that instead of you should put your .pyextension file name as created in step 4;
  • you should include each imported package in your .py into packages list (ex: packages = ["idna", "os","sys"])
  • any name, any number, any description in file should not remain the same, you should change it accordingly (ex:name = "<first_ever>", version = "0.11", description = '' )
  • the imported packages must be installed before you start step 8.

Deserialize JSON array(or list) in C#

This code works for me:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.Script.Serialization;

namespace Json
    class Program
        static void Main(string[] args)

        public static string DeserializeNames()
            var jsonData = "{\"name\":[{\"last\":\"Smith\"},{\"last\":\"Doe\"}]}";

            JavaScriptSerializer ser = new JavaScriptSerializer();

            nameList myNames = ser.Deserialize<nameList>(jsonData);

            return ser.Serialize(myNames);

        //Class descriptions

        public class name
            public string last { get; set; }

        public class nameList
            public List<name> name { get; set; }

Why do many examples use `fig, ax = plt.subplots()` in Matplotlib/pyplot/python

As a supplement to the question and above answers there is also an important difference between plt.subplots() and plt.subplot(), notice the missing 's' at the end.

One can use plt.subplots() to make all their subplots at once and it returns the figure and axes (plural of axis) of the subplots as a tuple. A figure can be understood as a canvas where you paint your sketch.

# create a subplot with 2 rows and 1 columns
fig, ax = plt.subplots(2,1)

Whereas, you can use plt.subplot() if you want to add the subplots separately. It returns only the axis of one subplot.

fig = plt.figure() # create the canvas for plotting
ax1 = plt.subplot(2,1,1) 
# (2,1,1) indicates total number of rows, columns, and figure number respectively
ax2 = plt.subplot(2,1,2)

However, plt.subplots() is preferred because it gives you easier options to directly customize your whole figure

# for example, sharing x-axis, y-axis for all subplots can be specified at once
fig, ax = plt.subplots(2,2, sharex=True, sharey=True)

Shared axes whereas, with plt.subplot(), one will have to specify individually for each axis which can become cumbersome.

Definitive way to trigger keypress events with jQuery

I made it work with keyup.

$("#id input").trigger('keyup');

what is this value means 1.845E-07 in excel?

Highlight the cells, format cells, select Custom then select zero.

Join two sql queries

Here's what worked for me:

select visits, activations, simulations, simulations/activations
   as sims_per_visit, activations/visits*100
   as adoption_rate, simulations/activations*100
   as completion_rate, duration/60
   as minutes, m1 as month, Wk1 as week, Yr1 as year 

    (select count(*) as visits, year(stamp) as Yr1, week(stamp) as Wk1, month(stamp)
    as m1 from sessions group by week(stamp), year(stamp)) as t3


    (select count(*) as activations, year(stamp) as Yr2, week(stamp) as Wk2,
    month(stamp) as m2 from sessions where activated='1' group by week(stamp),
    year(stamp)) as t4


    (select count(*) as simulations, year(stamp) as Yr3 , week(stamp) as Wk3,
    month(stamp) as m3 from sessions where simulations>'0' group by week(stamp),
    year(stamp)) as t5


    (select avg(duration) as duration, year(stamp) as Yr4 , week(stamp) as Wk4,
    month(stamp) as m4 from sessions where activated='1' group by week(stamp),
    year(stamp)) as t6
where Yr1=Yr2 and Wk1=Wk2 and Wk1=Wk3 and Yr1=Yr3 and Yr1=Yr4 and Wk1=Wk4

I used joins, not unions (I needed different columns for each query, a join puts it all in the same column) and I dropped the quotation marks (compared to what Liam was doing) because they were giving me errors.

Thanks! I couldn't have pulled that off without this page! PS: Sorry I don't know how you're getting your statements formatted with colors. etc.

How do you add an in-app purchase to an iOS application?

Swift Users

Swift users can check out My Swift Answer for this question.
Or, check out Yedidya Reiss's Answer, which translates this Objective-C code to Swift.

Objective-C Users

The rest of this answer is written in Objective-C

App Store Connect

  1. Go to and log in
  2. Click My Apps then click the app you want do add the purchase to
  3. Click the Features header, and then select In-App Purchases on the left
  4. Click the + icon in the middle
  5. For this tutorial, we are going to be adding an in-app purchase to remove ads, so choose non-consumable. If you were going to send a physical item to the user, or give them something that they can buy more than once, you would choose consumable.
  6. For the reference name, put whatever you want (but make sure you know what it is)
  7. For product id put tld.websitename.appname.referencename this will work the best, so for example, you could use com.jojodmo.blix.removeads
  8. Choose cleared for sale and then choose price tier as 1 (99¢). Tier 2 would be $1.99, and tier 3 would be $2.99. The full list is available if you click view pricing matrix I recommend you use tier 1, because that's usually the most anyone will ever pay to remove ads.
  9. Click the blue add language button, and input the information. This will ALL be shown to the customer, so don't put anything you don't want them seeing
  10. For hosting content with Apple choose no
  11. You can leave the review notes blank FOR NOW.
  12. Skip the screenshot for review FOR NOW, everything we skip we will come back to.
  13. Click 'save'

It could take a few hours for your product ID to register in App Store Connect, so be patient.

Setting up your project

Now that you've set up your in-app purchase information on App Store Connect, go into your Xcode project, and go to the application manager (blue page-like icon at the top of where your methods and header files are) click on your app under targets (should be the first one) then go to general. At the bottom, you should see linked frameworks and libraries click the little plus symbol and add the framework StoreKit.framework If you don't do this, the in-app purchase will NOT work!

If you are using Objective-C as the language for your app, you should skip these five steps. Otherwise, if you are using Swift, you can follow My Swift Answer for this question, here, or, if you prefer to use Objective-C for the In-App Purchase code but are using Swift in your app, you can do the following:

  1. Create a new .h (header) file by going to File > New > File... (Command ? + N). This file will be referred to as "Your .h file" in the rest of the tutorial

  2. When prompted, click Create Bridging Header. This will be our bridging header file. If you are not prompted, go to step 3. If you are prompted, skip step 3 and go directly to step 4.

  3. Create another .h file named Bridge.h in the main project folder, Then go to the Application Manager (the blue page-like icon), then select your app in the Targets section, and click Build Settings. Find the option that says Swift Compiler - Code Generation, and then set the Objective-C Bridging Header option to Bridge.h

  4. In your bridging header file, add the line #import "MyObjectiveCHeaderFile.h", where MyObjectiveCHeaderFile is the name of the header file that you created in step one. So, for example, if you named your header file InAppPurchase.h, you would add the line #import "InAppPurchase.h" to your bridge header file.

  5. Create a new Objective-C Methods (.m) file by going to File > New > File... (Command ? + N). Name it the same as the header file you created in step 1. For example, if you called the file in step 1 InAppPurchase.h, you would call this new file InAppPurchase.m. This file will be referred to as "Your .m file" in the rest of the tutorial.


Now we're going to get into the actual coding. Add the following code into your .h file:

BOOL areAdsRemoved;

- (IBAction)restore;
- (IBAction)tapsRemoveAds;

Next, you need to import the StoreKit framework into your .m file, as well as add SKProductsRequestDelegate and SKPaymentTransactionObserver after your @interface declaration:

#import <StoreKit/StoreKit.h>

//put the name of your view controller in place of MyViewController
@interface MyViewController() <SKProductsRequestDelegate, SKPaymentTransactionObserver>


@implementation MyViewController //the name of your view controller (same as above)
  //the code below will be added here

and now add the following into your .m file, this part gets complicated, so I suggest that you read the comments in the code:

//If you have more than one in-app purchase, you can define both of
//of them here. So, for example, you could define both kRemoveAdsProductIdentifier
//and kBuyCurrencyProductIdentifier with their respective product ids
//for this example, we will only use one product

#define kRemoveAdsProductIdentifier @"put your product id (the one that we just made in App Store Connect) in here"

- (IBAction)tapsRemoveAds{
    NSLog(@"User requests to remove ads");

    if([SKPaymentQueue canMakePayments]){
        NSLog(@"User can make payments");
        //If you have more than one in-app purchase, and would like
        //to have the user purchase a different product, simply define 
        //another function and replace kRemoveAdsProductIdentifier with 
        //the identifier for the other product

        SKProductsRequest *productsRequest = [[SKProductsRequest alloc] initWithProductIdentifiers:[NSSet setWithObject:kRemoveAdsProductIdentifier]];
        productsRequest.delegate = self;
        [productsRequest start];
        NSLog(@"User cannot make payments due to parental controls");
        //this is called the user cannot make payments, most likely due to parental controls

- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response{
    SKProduct *validProduct = nil;
    int count = [response.products count];
    if(count > 0){
        validProduct = [response.products objectAtIndex:0];
        NSLog(@"Products Available!");
        [self purchase:validProduct];
    else if(!validProduct){
        NSLog(@"No products available");
        //this is called if your product id is not valid, this shouldn't be called unless that happens.

- (void)purchase:(SKProduct *)product{
    SKPayment *payment = [SKPayment paymentWithProduct:product];

    [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
    [[SKPaymentQueue defaultQueue] addPayment:payment];

- (IBAction) restore{
    //this is called when the user restores purchases, you should hook this up to a button
    [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
    [[SKPaymentQueue defaultQueue] restoreCompletedTransactions];

- (void) paymentQueueRestoreCompletedTransactionsFinished:(SKPaymentQueue *)queue
    NSLog(@"received restored transactions: %i", queue.transactions.count);
    for(SKPaymentTransaction *transaction in queue.transactions){
        if(transaction.transactionState == SKPaymentTransactionStateRestored){
            //called when the user successfully restores a purchase
            NSLog(@"Transaction state -> Restored");

            //if you have more than one in-app purchase product,
            //you restore the correct product for the identifier.
            //For example, you could use
            //if(productID == kRemoveAdsProductIdentifier)
            //to get the product identifier for the
            //restored purchases, you can use
            //NSString *productID = transaction.payment.productIdentifier;
            [self doRemoveAds];
            [[SKPaymentQueue defaultQueue] finishTransaction:transaction];

- (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions{
    for(SKPaymentTransaction *transaction in transactions){
        //if you have multiple in app purchases in your app,
        //you can get the product identifier of this transaction
        //by using transaction.payment.productIdentifier
        //then, check the identifier against the product IDs
        //that you have defined to check which product the user
        //just purchased            

            case SKPaymentTransactionStatePurchasing: NSLog(@"Transaction state -> Purchasing");
                //called when the user is in the process of purchasing, do not add any of your own code here.
            case SKPaymentTransactionStatePurchased:
            //this is called when the user has successfully purchased the package (Cha-Ching!)
                [self doRemoveAds]; //you can add your code for what you want to happen when the user buys the purchase here, for this tutorial we use removing ads
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                NSLog(@"Transaction state -> Purchased");
            case SKPaymentTransactionStateRestored:
                NSLog(@"Transaction state -> Restored");
                //add the same code as you did from SKPaymentTransactionStatePurchased here
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
            case SKPaymentTransactionStateFailed:
                //called when the transaction does not finish
                if(transaction.error.code == SKErrorPaymentCancelled){
                    NSLog(@"Transaction state -> Cancelled");
                    //the user cancelled the payment ;(
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];

Now you want to add your code for what will happen when the user finishes the transaction, for this tutorial, we use removing adds, you will have to add your own code for what happens when the banner view loads.

- (void)doRemoveAds{
    ADBannerView *banner;
    [banner setAlpha:0];
    areAdsRemoved = YES;
    removeAdsButton.hidden = YES;
    removeAdsButton.enabled = NO;
    [[NSUserDefaults standardUserDefaults] setBool:areAdsRemoved forKey:@"areAdsRemoved"];
    //use NSUserDefaults so that you can load whether or not they bought it
    //it would be better to use KeyChain access, or something more secure
    //to store the user data, because NSUserDefaults can be changed.
    //You're average downloader won't be able to change it very easily, but
    //it's still best to use something more secure than NSUserDefaults.
    //For the purpose of this tutorial, though, we're going to use NSUserDefaults
    [[NSUserDefaults standardUserDefaults] synchronize];

If you don't have ads in your application, you can use any other thing that you want. For example, we could make the color of the background blue. To do this we would want to use:

- (void)doRemoveAds{
    [self.view setBackgroundColor:[UIColor blueColor]];
    areAdsRemoved = YES
    //set the bool for whether or not they purchased it to YES, you could use your own boolean here, but you would have to declare it in your .h file

    [[NSUserDefaults standardUserDefaults] setBool:areAdsRemoved forKey:@"areAdsRemoved"];
    //use NSUserDefaults so that you can load wether or not they bought it
    [[NSUserDefaults standardUserDefaults] synchronize];

Now, somewhere in your viewDidLoad method, you're going to want to add the following code:

areAdsRemoved = [[NSUserDefaults standardUserDefaults] boolForKey:@"areAdsRemoved"];
[[NSUserDefaults standardUserDefaults] synchronize];
//this will load wether or not they bought the in-app purchase

    [self.view setBackgroundColor:[UIColor blueColor]];
    //if they did buy it, set the background to blue, if your using the code above to set the background to blue, if your removing ads, your going to have to make your own code here

Now that you have added all the code, go into your .xib or storyboard file, and add two buttons, one saying purchase, and the other saying restore. Hook up the tapsRemoveAds IBAction to the purchase button that you just made, and the restore IBAction to the restore button. The restore action will check if the user has previously purchased the in-app purchase, and give them the in-app purchase for free if they do not already have it.

Submitting for review

Next, go into App Store Connect, and click Users and Access then click the Sandbox Testers header, and then click the + symbol on the left where it says Testers. You can just put in random things for the first and last name, and the e-mail does not have to be real - you just have to be able to remember it. Put in a password (which you will have to remember) and fill in the rest of the info. I would recommend that you make the Date of Birth a date that would make the user 18 or older. App Store Territory HAS to be in the correct country. Next, log out of your existing iTunes account (you can log back in after this tutorial).

Now, run your application on your iOS device, if you try running it on the simulator, the purchase will always error, you HAVE TO run it on your iOS device. Once the app is running, tap the purchase button. When you are prompted to log into your iTunes account, log in as the test user that we just created. Next,when it asks you to confirm the purchase of 99¢ or whatever you set the price tier too, TAKE A SCREEN SNAPSHOT OF IT this is what your going to use for your screenshot for review on App Store Connect. Now cancel the payment.

Now, go to App Store Connect, then go to My Apps > the app you have the In-app purchase on > In-App Purchases. Then click your in-app purchase and click edit under the in-app purchase details. Once you've done that, import the photo that you just took on your iPhone into your computer, and upload that as the screenshot for review, then, in review notes, put your TEST USER e-mail and password. This will help apple in the review process.

After you have done this, go back onto the application on your iOS device, still logged in as the test user account, and click the purchase button. This time, confirm the payment Don't worry, this will NOT charge your account ANY money, test user accounts get all in-app purchases for free After you have confirmed the payment, make sure that what happens when the user buys your product actually happens. If it doesn't, then thats going to be an error with your doRemoveAds method. Again, I recommend using changing the background to blue for testing the in-app purchase, this should not be your actual in-app purchase though. If everything works and you're good to go! Just make sure to include the in-app purchase in your new binary when you upload it to App Store Connect!

Here are some common errors:

Logged: No Products Available

This could mean four things:

  • You didn't put the correct in-app purchase ID in your code (for the identifier kRemoveAdsProductIdentifier in the above code
  • You didn't clear your in-app purchase for sale on App Store Connect
  • You didn't wait for the in-app purchase ID to be registered in App Store Connect. Wait a couple hours from creating the ID, and your problem should be resolved.
  • You didn't complete filling your Agreements, Tax, and Banking info.

If it doesn't work the first time, don't get frustrated! Don't give up! It took me about 5 hours straight before I could get this working, and about 10 hours searching for the right code! If you use the code above exactly, it should work fine. Feel free to comment if you have any questions at all.

I hope this helps to all of those hoping to add an in-app purchase to their iOS application. Cheers!

How to use PHP OPCache?

OPcache replaces APC

Because OPcache is designed to replace the APC module, it is not possible to run them in parallel in PHP. This is fine for caching PHP opcode as neither affects how you write code.

However it means that if you are currently using APC to store other data (through the apc_store() function) you will not be able to do that if you decide to use OPCache.

You will need to use another library such as either APCu or Yac which both store data in shared PHP memory, or switch to use something like memcached, which stores data in memory in a separate process to PHP.

Also, OPcache has no equivalent of the upload progress meter present in APC. Instead you should use the Session Upload Progress.

Settings for OPcache

The documentation for OPcache can be found here with all of the configuration options listed here. The recommended settings are:

; Sets how much memory to use

;Sets how much memory should be used by OPcache for storing internal strings 
;(e.g. classnames and the files they are contained in)

; The maximum number of files OPcache will cache

;How often (in seconds) to check file timestamps for changes to the shared
;memory storage allocation.

;If enabled, a fast shutdown sequence is used for the accelerated code
;The fast shutdown sequence doesn't free each allocated block, but lets
;the Zend Engine Memory Manager do the work.

;Enables the OPcache for the CLI version of PHP.

If you use any library or code that uses code annotations you must enable save comments:


If disabled, all PHPDoc comments are dropped from the code to reduce the size of the optimized code. Disabling "Doc Comments" may break some existing applications and frameworks (e.g. Doctrine, ZF2, PHPUnit)

How to use android emulator for testing bluetooth application?

You can't. The emulator does not support Bluetooth, as mentioned in the SDK's docs and several other places. Android emulator does not have bluetooth capabilities".

You can only use real devices.

Emulator Limitations

The functional limitations of the emulator include:

  • No support for placing or receiving actual phone calls. However, You can simulate phone calls (placed and received) through the emulator console
  • No support for USB
  • No support for device-attached headphones
  • No support for determining SD card insert/eject
  • No support for WiFi, Bluetooth, NFC

Refer to the documentation

Automatic date update in a cell when another cell's value changes (as calculated by a formula)

You could fill the dependend cell (D2) by a User Defined Function (VBA Macro Function) that takes the value of the C2-Cell as input parameter, returning the current date as ouput.

Having C2 as input parameter for the UDF in D2 tells Excel that it needs to reevaluate D2 everytime C2 changes (that is if auto-calculation of formulas is turned on for the workbook).


Here is some code:

For the UDF:

    Public Function UDF_Date(ByVal data) As Date

        UDF_Date = Now()

    End Function

As Formula in D2:


You will have to give the D2-Cell a Date-Time Format, or it will show a numeric representation of the date-value.

And you can expand the formula over the desired range by draging it if you keep the C2 reference in the D2-formula relative.

Note: This still might not be the ideal solution because every time Excel recalculates the workbook the date in D2 will be reset to the current value. To make D2 only reflect the last time C2 was changed there would have to be some kind of tracking of the past value(s) of C2. This could for example be implemented in the UDF by providing also the address alonside the value of the input parameter, storing the input parameters in a hidden sheet, and comparing them with the previous values everytime the UDF gets called.


Here is a sample implementation of an UDF that tracks the changes of the cell values and returns the date-time when the last changes was detected. When using it, please be aware that:

  • The usage of the UDF is the same as described above.

  • The UDF works only for single cell input ranges.

  • The cell values are tracked by storing the last value of cell and the date-time when the change was detected in the document properties of the workbook. If the formula is used over large datasets the size of the file might increase considerably as for every cell that is tracked by the formula the storage requirements increase (last value of cell + date of last change.) Also, maybe Excel is not capable of handling very large amounts of document properties and the code might brake at a certain point.

  • If the name of a worksheet is changed all the tracking information of the therein contained cells is lost.

  • The code might brake for cell-values for which conversion to string is non-deterministic.

  • The code below is not tested and should be regarded only as proof of concept. Use it at your own risk.

    Public Function UDF_Date(ByVal inData As Range) As Date
        Dim wb As Workbook
        Dim dProps As DocumentProperties
        Dim pValue As DocumentProperty
        Dim pDate As DocumentProperty
        Dim sName As String
        Dim sNameDate As String
        Dim bDate As Boolean
        Dim bValue As Boolean
        Dim bChanged As Boolean
        bDate = True
        bValue = True
        bChanged = False
        Dim sVal As String
        Dim dDate As Date
        sName = inData.Address & "_" & inData.Worksheet.Name
        sNameDate = sName & "_dat"
        sVal = CStr(inData.Value)
        dDate = Now()
        Set wb = inData.Worksheet.Parent
        Set dProps = wb.CustomDocumentProperties
    On Error Resume Next
        Set pValue = dProps.Item(sName)
        If Err.Number <> 0 Then
            bValue = False
        End If
    On Error GoTo 0
        If Not bValue Then
            bChanged = True
            Set pValue = dProps.Add(sName, False, msoPropertyTypeString, sVal)
            bChanged = pValue.Value <> sVal
            If bChanged Then
                pValue.Value = sVal
            End If
        End If
    On Error Resume Next
        Set pDate = dProps.Item(sNameDate)
        If Err.Number <> 0 Then
            bDate = False
        End If
    On Error GoTo 0
        If Not bDate Then
            Set pDate = dProps.Add(sNameDate, False, msoPropertyTypeDate, dDate)
        End If
        If bChanged Then
            pDate.Value = dDate
            dDate = pDate.Value
        End If
        UDF_Date = dDate
     End Function

Make the insertion of the date conditional upon the range.

This has an advantage of not changing the dates unless the content of the cell is changed, and it is in the range C2:C2, even if the sheet is closed and saved, it doesn't recalculate unless the adjacent cell changes.

Adapted from this tip and @Paul S answer

Private Sub Worksheet_Change(ByVal Target As Range)
 Dim R1 As Range
 Dim R2 As Range
 Dim InRange As Boolean
    Set R1 = Range(Target.Address)
    Set R2 = Range("C2:C20")
    Set InterSectRange = Application.Intersect(R1, R2)

  InRange = Not InterSectRange Is Nothing
     Set InterSectRange = Nothing
   If InRange = True Then
     R1.Offset(0, 1).Value = Now()
   End If
     Set R1 = Nothing
     Set R2 = Nothing
 End Sub

Convert datetime object to a String of date only in Python

Another option:

import datetime
# ouptut --> '2016-03-09T08:18:20.860968'

To the power of in C?

For another approach, note that all the standard library functions work with floating point types. You can implement an integer type function like this:

unsigned power(unsigned base, unsigned degree)
    unsigned result = 1;
    unsigned term = base;
    while (degree)
        if (degree & 1)
            result *= term;
        term *= term;
        degree = degree >> 1;
    return result;

This effectively does repeated multiples, but cuts down on that a bit by using the bit representation. For low integer powers this is quite effective.

What's the difference between "Request Payload" vs "Form Data" as seen in Chrome dev tools Network tab

In Chrome, request with 'Content-Type:application/json' shows as Request PayedLoad and sends data as json object.

But request with 'Content-Type:application/x-www-form-urlencoded' shows Form Data and sends data as Key:Value Pair, so if you have array of object in one key it flats that key's value:

{ Id: 1, 


{ Id: 1, 
phones:[object object]
phones:[object object]


Maybe you have run into this problem: net::ERR_INSECURE_RESPONSE

You need to check the encryption algorithms supported by your server. For example for apache you can configure the cipher suite this way: cipher suite.

Which version of chrome are you running and what is the server serving your APIs?

How to get Month Name from Calendar?

You will get this way also.

  String getMonthForInt(int num) {
        String month = "wrong";
        DateFormatSymbols dfs = new DateFormatSymbols();
        String[] months = dfs.getMonths();
        if (num >= 0 && num <= 11 ) {
            month = months[num];
        return month;

MySql server startup error 'The server quit without updating PID file '

In my case, the problem was, that mysql data directory was moved by accident to wrong directory (/var/log, and not to /var/lib). After moving data back to /var/lib/mysql and restarting server, all everything went back to normal again.

Get the current year in JavaScript

for current year we can use getFullYear() from Date class however there are many function which you can use as per the requirements, some functions are as,

var now = new Date()_x000D_
console.log("Current Time is: " + now);_x000D_
// getFullYear function will give current year _x000D_
var currentYear = now.getFullYear()_x000D_
console.log("Current year is: " + currentYear);_x000D_
// getYear will give you the years after 1990 i.e currentYear-1990_x000D_
var year = now.getYear()_x000D_
console.log("Current year is: " + year);_x000D_
// getMonth gives the month value but months starts from 0_x000D_
// add 1 to get actual month value _x000D_
var month = now.getMonth() + 1_x000D_
console.log("Current month is: " + month);_x000D_
// getDate gives the date value_x000D_
var day = now.getDate()_x000D_
console.log("Today's day is: " + day);

PHPMailer AddAddress()

You need to call the AddAddress function once for each E-Mail address you want to send to. There are only two arguments for this function: recipient_email_address and recipient_name. The recipient name is optional and will not be used if not present.

$mailer->AddAddress('[email protected]', 'First Name');
$mailer->AddAddress('[email protected]', 'Second Name');
$mailer->AddAddress('[email protected]', 'Third Name');

You could use an array to store the recipients and then use a for loop. I hope it helps.

How to remove application from app listings on Android Developer Console

The one exception worth noting is that while you can't delete apps, the folks over at Google Play Developer Support are able to on their end if the app is both unpublished and has 0 lifetime installs. So if your app has 0 lifetime installs, you might be in luck.

First you will need unpublish the app and wait 24 hours (to allow global stats to update and ensure that no last-minute installs happened). Assuming no last-minute installs happen over those 24 hours, you can contact Google Play Developer Support and check to see if they can delete it.

Please note that their requirement for 0 installs is a hard requirement. No exceptions can be made (not even if you installed the app yourself for testing purposes).

NullInjectorError: No provider for AngularFirestore

Change Your Import From :

import { AngularFirestore } from '@angular/fire/firestore/firestore';

To This :

import { AngularFirestore } from '@angular/fire/firestore';

This solve my problem.

How to launch an EXE from Web page (

You can see how iTunes does it by using Fiddler to follow the action when using the link:

  1. It downloads a js file
  2. On windows: the js file determines if iTunes was installed on the computer or not: looks for an activeX browser component if IE, or a browser plugin if FF
  3. If iTunes is installed then the browser is redirected to an URL with a special transport: itms://...
  4. The browser invokes the handler (provided by the iTunes exe). This includes starting up the exe if it is not already running.
  5. iTunes exe uses the rest of the special url to show a specific page to the user.

Note that the exe, when installed, installed URL protocol handlers for "itms" transport with the browsers.

Not a simple engineering project to duplicate, but definitely do-able. If you go ahead with this, please consider making the relevant software open source.

JDBC connection to MSSQL server in windows authentication mode

From your exception trace, it looks like there is multiple possibility for this problem

1). You have to check that your port "1433" is blocked by firewall or not. If you find that it is blocked then you should have to write "Inbound Rule". It if found in control panel -> windows firewall -> Advance Setting (Option found at Left hand side) -> Inbound Rule.

2). In SQL Server configuration Manager, your TCP/IP protocol will find in disable mode. So, you should have to enable it.

gnuplot plotting multiple line graphs

I think your problem is your version numbers. Try making 8.1 --> 8.01, and so forth. That should put the points in the right order.

Alternatively, you could plot using X, where X is the column number you want, instead of using 1:X. That will plot those values on the y axis and integers on the x axis. Try:

plot "ls.dat" using 2 title 'Removed' with lines, \
     "ls.dat" using 3 title 'Added' with lines, \
     "ls.dat" using 4 title 'Modified' with lines

How to connect android emulator to the internet

There are different solutions to this problem . One of these , i will show you on my experiment and outcomes seen on results using a recent android studio and AVD images downloaded 2017.

  1. First thing you have to do is launch your AVD from android studio.(in my case i choose NEXUSAPI25 android 7.1 image)

  2. Goto Settings->Wirless and Networking - > Cellular Network - > Access Points -> (+) press add - > enter the following if you dont have NTLM proxy or proxy at all (that means you are directly connected)

    a. add apn name as myAPN b. add apn server => www c. save and try browsing the internet.

if this doesn work add 'ANDROID_SDK_ROOT' in you environment variable

Then , launch AVD using emulator command as follow

emulator -avd Nexus25 -dns-server
  1. For those who use NTLM proxies , i will show you how it work for me next.

  2. add your Android_sdk_root path into your environment variable. THis make command line code read succesfully like using AVD names and so on.

  3. Launch your emaulator using the following command

>emulator -avd Nexus_5X_API_25 -http-proxy http://username:password@ipaddress:port


enter image description here

enter image description here

When to use EntityManager.find() vs EntityManager.getReference() with JPA

I disagree with the selected answer, and as davidxxx correctly pointed out, getReference does not provide such behaviour of dynamic updations without select. I asked a question concerning the validity of this answer, see here - cannot update without issuing select on using setter after getReference() of hibernate JPA.

I quite honestly haven't seen anybody who's actually used that functionality. ANYWHERE. And i don't understand why it's so upvoted.

Now first of all, no matter what you call on a hibernate proxy object, a setter or a getter, an SQL is fired and the object is loaded.

But then i thought, so what if JPA getReference() proxy doesn't provide that functionality. I can just write my own proxy.

Now, we can all argue that selects on primary keys are as fast as a query can get and it's not really something to go to great lengths to avoid. But for those of us who can't handle it due to one reason or another, below is an implementation of such a proxy. But before i you see the implementation, see it's usage and how simple it is to use.


Order example = ProxyHandler.getReference(Order.class, 3);

And this would fire the following query -

UPDATE Order SET type = 'ABCD' and cost = 10 WHERE id = 3;

and even if you want to insert, you can still do Order("a", 2)); and it would fire an insert as it should.


Add this to your pom.xml -


Make this class to create dynamic proxy -

public class ProxyHandler {

public static <T> T getReference(Class<T> classType, Object id) {
    if (!classType.isAnnotationPresent(Entity.class)) {
        throw new ProxyInstantiationException("This is not an entity!");

    try {
        Enhancer enhancer = new Enhancer();
        enhancer.setCallback(new ProxyMethodInterceptor(classType, id));
        enhancer.setInterfaces((new Class<?>[]{EnhancedProxy.class}));
        return (T) enhancer.create();
    } catch (Exception e) {
        throw new ProxyInstantiationException("Error creating proxy, cause :" + e.getCause());

Make an interface with all the methods -

public interface EnhancedProxy {
    public String getJPQLUpdate();
    public HashMap<String, Object> getModifiedFields();

Now, make an interceptor which will allow you to implement these methods on your proxy -

import javafx.util.Pair;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import javax.persistence.Id;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.*;
* @author Anil Kumar
public class ProxyMethodInterceptor implements MethodInterceptor, EnhancedProxy {

private Object target;
private Object proxy;
private Class classType;
private Pair<String, Object> primaryKey;
private static HashSet<String> enhancedMethods;

ProxyMethodInterceptor(Class classType, Object id) throws IllegalAccessException, InstantiationException {
    this.classType = classType; = classType.newInstance();
    this.primaryKey = new Pair<>(getPrimaryKeyField().getName(), id);

static {
    enhancedMethods = new HashSet<>();
    for (Method method : EnhancedProxy.class.getDeclaredMethods()) {

public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
    //intercept enhanced methods
    if (enhancedMethods.contains(method.getName())) {
        this.proxy = obj;
        return method.invoke(this, args);
    //else invoke super class method
        return proxy.invokeSuper(obj, args);

public HashMap<String, Object> getModifiedFields() {
    HashMap<String, Object> modifiedFields = new HashMap<>();
    try {
        for (Field field : classType.getDeclaredFields()) {


            Object initialValue = field.get(target);
            Object finalValue = field.get(proxy);

            //put if modified
            if (!Objects.equals(initialValue, finalValue)) {
                modifiedFields.put(field.getName(), finalValue);
    } catch (Exception e) {
        return null;
    return modifiedFields;

public String getJPQLUpdate() {
    HashMap<String, Object> modifiedFields = getModifiedFields();
    if (modifiedFields == null || modifiedFields.isEmpty()) {
        return null;
    StringBuilder fieldsToSet = new StringBuilder();
    for (String field : modifiedFields.keySet()) {
        fieldsToSet.append(field).append(" = :").append(field).append(" and ");
    fieldsToSet.setLength(fieldsToSet.length() - 4);
    return "UPDATE "
            + classType.getSimpleName()
            + " SET "
            + fieldsToSet
            + "WHERE "
            + primaryKey.getKey() + " = " + primaryKey.getValue();

private Field getPrimaryKeyField() throws ProxyInstantiationException {
    for (Field field : classType.getDeclaredFields()) {
        if (field.isAnnotationPresent(Id.class))
            return field;
    throw new ProxyInstantiationException("Entity class doesn't have a primary key!");

And the exception class -

public class ProxyInstantiationException extends RuntimeException {
public ProxyInstantiationException(String message) {

A service to save using this proxy -

public class PersistenceService {

private EntityManager em;

private void save(Object entity) {
    // update entity for proxies
    if (entity instanceof EnhancedProxy) {
        EnhancedProxy proxy = (EnhancedProxy) entity;
        Query updateQuery = em.createQuery(proxy.getJPQLUpdate());
        for (Entry<String, Object> entry : proxy.getModifiedFields().entrySet()) {
            updateQuery.setParameter(entry.getKey(), entry.getValue());
    // insert otherwise
    } else {


Exponentiation in Python - should I prefer ** operator instead of math.pow and math.sqrt?

Even in base Python you can do the computation in generic form

result = sum(x**2 for x in some_vector) ** 0.5

x ** 2 is surely not an hack and the computation performed is the same (I checked with cpython source code). I actually find it more readable (and readability counts).

Using instead x ** 0.5 to take the square root doesn't do the exact same computations as math.sqrt as the former (probably) is computed using logarithms and the latter (probably) using the specific numeric instruction of the math processor.

I often use x ** 0.5 simply because I don't want to add math just for that. I'd expect however a specific instruction for the square root to work better (more accurately) than a multi-step operation with logarithms.

Write string to text file and ensure it always overwrites the existing content.

Use the File.WriteAllText method. It creates the file if it doesn't exist and overwrites it if it exists.

How to generate .NET 4.0 classes from xsd?

Along with WSDL, I had xsd files. The above did not work in my case gave error. It worked as follows

wsdl /l:C# /out:D:\FileName.cs D:\NameApi\wsdl_1_1\RESAdapterService.wsdl 
D:\CXTypes.xsd D:\CTypes.xsd 

How can I make a div not larger than its contents?

You can do it simply by using display: inline; (or white-space: nowrap;).

I hope you find this useful.

raw_input function in Python

The raw_input() function reads a line from input (i.e. the user) and returns a string

Python v3.x as raw_input() was renamed to input()

PEP 3111: raw_input() was renamed to input(). That is, the new input() function reads a line from sys.stdin and returns it with the trailing newline stripped. It raises EOFError if the input is terminated prematurely. To get the old behavior of input(), use eval(input()).

Ref: Docs Python 3

PHP Warning: PHP Startup: Unable to load dynamic library

Loading .dll in Linux

I've encountered this warning message while I was trying to install a php-extension via the php.ini file;

until I figured out that you cannot load .dll extensions in Linux,

but you have to comment the extensions that you want to import ;extension= ... .dll and install it correctly via sudo apt-get install php-...

note: ... is the extension name you want to enable.

How can I get the count of milliseconds since midnight for the current?

Do you mean?

long millis = System.currentTimeMillis() % 1000;

BTW Windows doesn't allow timetravel to 1969

C:\> date
Enter the new date: (dd-mm-yy) 2/8/1969
The system cannot accept the date entered.

Mysql service is missing

I came across the same problem. I properly installed the MYSQL Workbench 6.x, but faced the connection as below:

enter image description here

I did a bit R&D on this and found that MySQL service in service.msc is not present. To achieve this I created a new connection in MySQL Workbench then manually configured the MySQL Database Server in "System Profile" (see the below picture).

You also need to install MySQL Database Server and set a configuration file path for my.ini. Now at last test the connection (make sure MySQL service is running in services.msc).

enter image description here

JavaScript - Get Portion of URL Path

If you have an abstract URL string (not from the current window.location), you can use this trick:

let yourUrlString = "";

let parser = document.createElement('a');
parser.href = yourUrlString;

parser.protocol; // => "http:"
parser.hostname; // => ""
parser.port;     // => "3000"
parser.pathname; // => "/pathname/";   // => "?search=test"
parser.hash;     // => "#hash";     // => ""

Thanks to jlong

ASP.Net MVC Redirect To A Different View

You can use the RedirectToAction() method, then the action you redirect to can return a View. The easiest way to do this is:

return RedirectToAction("Index", model);

Then in your Index method, return the view you want.

How to get label text value form a html page?

For cases where the data element is inside the label like in this example:

<label for="subscription">Subscription period
    <select id='subscription' name='subscription'>
        <option>1 year</option>
        <option>2 years</option>
        <option>3 years</option>

all the previous answers will give an unexpected result:

"Subscription period

                    1 year
                    2 years
                    3 years


While the expected result would be:

"Subscription period"

So, the correct solution will be like this:

const label = document.getElementById('yourLableId');
const labelText = Array.prototype.filter
    .call(label.childNodes, x => x.nodeName === "#text")
    .map(x => x.textContent)
    .join(" ")

C library function to perform sort

I think you are looking for qsort.
qsort function is the implementation of quicksort algorithm found in stdlib.h in C/C++.

Here is the syntax to call qsort function:

void qsort(void *base, size_t nmemb, size_t size,int (*compar)(const void *, const void *));

List of arguments:

base: pointer to the first element or base address of the array
nmemb: number of elements in the array
size: size in bytes of each element
compar: a function that compares two elements

Here is a code example which uses qsort to sort an array:

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

int arr[] = { 33, 12, 6, 2, 76 };

// compare function, compares two elements
int compare (const void * num1, const void * num2) {
   if(*(int*)num1 > *(int*)num2)
    return 1;
    return -1;

int main () {
   int i;

   printf("Before sorting the array: \n");
   for( i = 0 ; i < 5; i++ ) {
      printf("%d ", arr[i]);
   // calling qsort
   qsort(arr, 5, sizeof(int), compare);

   printf("\nAfter sorting the array: \n");
   for( i = 0 ; i < 5; i++ ) {   
      printf("%d ", arr[i]);
   return 0;

You can type man 3 qsort in Linux/Mac terminal to get a detailed info about qsort.
Link to qsort man page

How to define a List bean in Spring?

I think you may be looking for org.springframework.beans.factory.config.ListFactoryBean.

You declare a ListFactoryBean instance, providing the list to be instantiated as a property withe a <list> element as its value, and give the bean an id attribute. Then, each time you use the declared id as a ref or similar in some other bean declaration, a new copy of the list is instantiated. You can also specify the List class to be used.

Differences between action and actionListener

As BalusC indicated, the actionListener by default swallows exceptions, but in JSF 2.0 there is a little more to this. Namely, it doesn't just swallows and logs, but actually publishes the exception.

This happens through a call like this:

context.getApplication().publishEvent(context, ExceptionQueuedEvent.class,                                                          
    new ExceptionQueuedEventContext(context, exception, source, phaseId)

The default listener for this event is the ExceptionHandler which for Mojarra is set to com.sun.faces.context.ExceptionHandlerImpl. This implementation will basically rethrow any exception, except when it concerns an AbortProcessingException, which is logged. ActionListeners wrap the exception that is thrown by the client code in such an AbortProcessingException which explains why these are always logged.

This ExceptionHandler can be replaced however in faces-config.xml with a custom implementation:


Instead of listening globally, a single bean can also listen to these events. The following is a proof of concept of this:

public class MyBean {

    public void actionMethod(ActionEvent event) {

        FacesContext.getCurrentInstance().getApplication().subscribeToEvent(ExceptionQueuedEvent.class, new SystemEventListener() {

        public void processEvent(SystemEvent event) throws AbortProcessingException {
            ExceptionQueuedEventContext content = (ExceptionQueuedEventContext)event.getSource();
            throw new RuntimeException(content.getException());

        public boolean isListenerForSource(Object source) {
            return true;

        throw new RuntimeException("test");


(note, this is not how one should normally code listeners, this is only for demonstration purposes!)

Calling this from a Facelet like this:

<html xmlns=""
            <h:commandButton value="test" actionListener="#{myBean.actionMethod}"/>

Will result in an error page being displayed.

Nginx sites-enabled, sites-available: Cannot create soft-link between config files in Ubuntu 12.04

My site configuration file is example.conf in sites-available folder So you can create a symbolic link as

ln -s /etc/nginx/sites-available/example.conf /etc/nginx/sites-enabled/

Using set_facts and with_items together in Ansible

As mentioned in other people's comments, the top solution given here was not working for me in Ansible 2.2, particularly when also using with_items.

It appears that OP's intended approach does work now with a slight change to the quoting of item.

- set_fact: something="{{ something + [ item ] }}"
    - one
    - two
    - three

And a longer example where I've handled the initial case of the list being undefined and added an optional when because that was also causing me grief:

- set_fact: something="{{ something|default([]) + [ item ] }}"
    - one
    - two
    - three
  when: in allowed_things.item_list

DataTable, How to conditionally delete rows

Here's a one-liner using LINQ and avoiding any run-time evaluation of select strings:

    r => r.ItemArray[0] == someValue).ToList().ForEach(r => r.Delete());

Android Studio: Default project directory

At some point I too tried to do this, but the Android Studio doesn’t work quite like Eclipse does.

It's simpler: if you create a project at, say /home/USER/Projects/AndroidStudio/MyApplication from there on all new projects will default to /home/USER/Projects/AndroidStudio.

You can also edit ~/.AndroidStudioPreview/config/options/ide.general.xml (in linux) and change the line that reads <option name="lastProjectLocation" value="$USER_HOME$/AndroidStudioProjects" /> to <option name="lastProjectLocation" value="$USER_HOME$/Projects/AndroidStudio" />, but be aware that as soon as you create a project anywhere else this will change to that place and all new projects will default to it.

Hope this helps, but the truth is there really isn't much more to it other than what I explained here.

Let me know if you need anything else.

How to make promises work in IE11

If you want this type of code to run in IE11 (which does not support much of ES6 at all), then you need to get a 3rd party promise library (like Bluebird), include that library and change your coding to use ES5 coding structures (no arrow functions, no let, etc...) so you can live within the limits of what older browsers support.

Or, you can use a transpiler (like Babel) to convert your ES6 code to ES5 code that will work in older browsers.

Here's a version of your code written in ES5 syntax with the Bluebird promise library:

<script src=""></script>


'use strict';

var promise = new Promise(function(resolve) {
    setTimeout(function() {
    }, 1000);

promise.then(function(result) {
    alert("Fulfilled: " + result);
}, function(error) {
    alert("Rejected: " + error);


Notepad++ change text color?

You can Change it from:

Menu Settings -> Style Configurator

See on screenshot:

enter image description here

SQL Server reports 'Invalid column name', but the column is present and the query works through management studio

In my case I was trying to get the value from wrong ResultSet when querying multiple SQL statements.

What does "yield break;" do in C#?

yield break is just a way of saying return for the last time and don't return any value


// returns 1,2,3,4,5
IEnumerable<int> CountToFive()
    yield return 1;
    yield return 2;
    yield return 3;
    yield return 4;
    yield return 5;
    yield break;
    yield return 6;
    yield return 7;
    yield return 8;
    yield return 9;

Handling data in a PHP JSON Object

Just use it like it was an object you defined. i.e.

$trends = $json_output->trends;

What is Hash and Range Primary Key?

"Hash and Range Primary Key" means that a single row in DynamoDB has a unique primary key made up of both the hash and the range key. For example with a hash key of X and range key of Y, your primary key is effectively XY. You can also have multiple range keys for the same hash key but the combination must be unique, like XZ and XA. Let's use their examples for each type of table:

Hash Primary Key – The primary key is made of one attribute, a hash attribute. For example, a ProductCatalog table can have ProductID as its primary key. DynamoDB builds an unordered hash index on this primary key attribute.

This means that every row is keyed off of this value. Every row in DynamoDB will have a required, unique value for this attribute. Unordered hash index means what is says - the data is not ordered and you are not given any guarantees into how the data is stored. You won't be able to make queries on an unordered index such as Get me all rows that have a ProductID greater than X. You write and fetch items based on the hash key. For example, Get me the row from that table that has ProductID X. You are making a query against an unordered index so your gets against it are basically key-value lookups, are very fast, and use very little throughput.

Hash and Range Primary Key – The primary key is made of two attributes. The first attribute is the hash attribute and the second attribute is the range attribute. For example, the forum Thread table can have ForumName and Subject as its primary key, where ForumName is the hash attribute and Subject is the range attribute. DynamoDB builds an unordered hash index on the hash attribute and a sorted range index on the range attribute.

This means that every row's primary key is the combination of the hash and range key. You can make direct gets on single rows if you have both the hash and range key, or you can make a query against the sorted range index. For example, get Get me all rows from the table with Hash key X that have range keys greater than Y, or other queries to that affect. They have better performance and less capacity usage compared to Scans and Queries against fields that are not indexed. From their documentation:

Query results are always sorted by the range key. If the data type of the range key is Number, the results are returned in numeric order; otherwise, the results are returned in order of ASCII character code values. By default, the sort order is ascending. To reverse the order, set the ScanIndexForward parameter to false

I probably missed some things as I typed this out and I only scratched the surface. There are a lot more aspects to take into consideration when working with DynamoDB tables (throughput, consistency, capacity, other indices, key distribution, etc.). You should take a look at the sample tables and data page for examples.

Converting XDocument to XmlDocument and vice versa

If you need to convert the instance of System.Xml.Linq.XDocument into the instance of the System.Xml.XmlDocument this extension method will help you to do not lose the XML declaration in the resulting XmlDocument instance:

using System.Xml; 
using System.Xml.Linq;

    internal static class LinqHelper 
        public static XmlDocument ToXmlDocument(this XDocument xDocument) 
            var xmlDocument = new XmlDocument(); 
            using (var reader = xDocument.CreateReader()) 

            var xDeclaration = xDocument.Declaration; 
            if (xDeclaration != null) 
                var xmlDeclaration = xmlDocument.CreateXmlDeclaration( 

                xmlDocument.InsertBefore(xmlDeclaration, xmlDocument.FirstChild); 

            return xmlDocument; 

Hope that helps!

Difference between final and effectively final

The Effectively final variable is a local variable that is:

  1. Not defined as final
  2. Assigned to ONLY once.

While a final variable is a variable that is:

  1. declared with a final keyword.

jQuery check if Cookie exists, if not create it

I was having alot of trouble with this because I was using:

if($.cookie('token') === null || $.cookie('token') === "")
      //no cookie
     //have cookie

The above was ALWAYS returning false, no matter what I did in terms of setting the cookie or not. From my tests it seems that the object is therefore undefined before it's set so adding the following to my code fixed it.

if($.cookie('token') === null || $.cookie('token') === "" 
    || $.(cookie('token') === "null" || $.cookie('token') === undefined)
      //no cookie
     //have cookie

FileSystemWatcher Changed event is raised twice

Event if not asked, it is a shame there are no ready solution samples for F#. To fix this here is my recipe, just because I can and F# is a wonderful .NET language.

Duplicated events are filtered out using FSharp.Control.Reactive package, which is just a F# wrapper for reactive extensions. All that can be targeted to full framework or netstandard2.0:

let createWatcher path filter () =
    new FileSystemWatcher(
        Path = path,
        Filter = filter,
        EnableRaisingEvents = true,
        SynchronizingObject = null // not needed for console applications

let createSources (fsWatcher: FileSystemWatcher) =
    // use here needed events only. 
    // convert `Error` and `Renamed` events to be merded
    [| fsWatcher.Changed :> IObservable<_>
       fsWatcher.Deleted :> IObservable<_>
       fsWatcher.Created :> IObservable<_>
       //fsWatcher.Renamed |> renamedToNeeded
       //fsWatcher.Error   |> errorToNeeded
    |] |> Observable.mergeArray

let handle (e: FileSystemEventArgs) =
    printfn "handle %A event '%s' '%s' " e.ChangeType e.Name e.FullPath 

let watch path filter throttleTime =
    // disposes watcher if observer subscription is disposed
    Observable.using (createWatcher path filter) createSources
    // filter out multiple equal events
    |> Observable.distinctUntilChanged
    // filter out multiple Changed
    |> Observable.throttle throttleTime
    |> Observable.subscribe handle

let main _args =
    let path = @"C:\Temp\WatchDir"
    let filter = "*.zip"
    let throttleTime = TimeSpan.FromSeconds 10.
    use _subscription = watch path filter throttleTime
    System.Console.ReadKey() |> ignore
    0 // return an integer exit code

Why doesn't importing java.util.* include Arrays and Lists?

Take a look at this forum Theres a discussion on how using wildcards can lead to conflicts if you add new classes to the packages and if there are two classes with the same name in different packages where only one of them will be imported.


It gives that warning because your the line should actually be

List<Integer> i = new ArrayList<Integer>(Arrays.asList(0,1,2,3,4,5,6,7,8,9,10));
List<Integer> j = new ArrayList<Integer>();

You need to specify the type for array list or the compiler will give that warning because it cannot identify that you are using the list in a type safe way.

Getting new Twitter API consumer and secret keys

To get Consumer Key & Consumer Secret, you have to create an app in Twitter via

Then you'll be taken to a page containing Consumer Key & Consumer Secret.

Hopefully this information will clarify OAuth essentials for Twitter:

  1. Create a Twitter account if you don't already have one
  2. Visit '' and follow the required prompts to create a developer project (Twitter requires you to answer some questions before they will approve your account. Approval was nearly instant in my case.)
  3. Requesting the API key and secret via the Developer Portal causes Twitter to produce the following three things:
  • API key (this is your 'consumer key')
  • API secret key (this is your 'consumer secret')
  • Bearer token
  1. Next, visit the 'Authentication Tokens' area of the Developer Portal and generate an 'Access token & secret'. This will provide you with the following two items:
  • Access token (this is your 'token key')
  • Access token secret (this is your 'token secret')
  1. The consumer key, consumer secret, token key, and token secret should be sufficient to do Twitter API calls (they were for me). Good luck!

"The system cannot find the file C:\ProgramData\Oracle\Java\javapath\java.exe"

Don't worry. Just uninstall jdk as well as jdk updates Before re installing jdk ,delete the oracle folder inside programData hidden folder in C:\ Then reinstall. Set the following,

JRE_HOME ( is optional)

How to prettyprint a JSON file?

I think that's better to parse the json before, to avoid errors:

def format_response(response):
        parsed = json.loads(response.text)
    except JSONDecodeError:
        return response.text
    return json.dumps(parsed, ensure_ascii=True, indent=4)

CSS @media print issues with background-color;

For Chrome:::::::::::::::::

Ctrl+P => Select the Click On More Settings => In the Options Menu Select the Background and Graphics Options

                      :) Will Work

**Why wasn't it working!Reason:**Chrome Browser had Fonts And Headers Enabled

General Case:::::

When you dont need to turn on this option manually.In body in CSS type:::::

-webkit-print-color-adjust:exact !important;


How to declare a global variable in JavaScript

If you have to generate global variables in production code (which should be avoided) always declare them explicitly:

window.globalVar = "This is global!";

While it is possible to define a global variable by just omitting var (assuming there is no local variable of the same name), doing so generates an implicit global, which is a bad thing to do and would generate an error in strict mode.

Can I scroll a ScrollView programmatically in Android?

**to scroll up to desired height. I have come up with some good solution **

                scrollView.postDelayed(new Runnable() {
                    public void run() {
                        scrollView.scrollBy(0, childView.getHeight());
                }, 100);

Is there a CSS selector for text nodes?

You cannot target text nodes with CSS. I'm with you; I wish you could... but you can't :(

If you don't wrap the text node in a <span> like @Jacob suggests, you could instead give the surrounding element padding as opposed to margin:


<p id="theParagraph">The text node!</p>


    border: 1px solid red;
    padding-bottom: 10px;

How do I pass multiple parameters into a function in PowerShell?

Function Test {
    Param([string]$arg1, [string]$arg2)

    Write-Host $arg1
    Write-Host $arg2

This is a proper params declaration.

See about_Functions_Advanced_Parameters.

And it indeed works.

Java 8 Lambda filter by Lists

Predicate<Client> hasSameNameAsOneUser = 
    c -> -> u.getName().equals(c.getName()));


But this is quite inefficient, because it's O(m * n). You'd better create a Set of acceptable names:

Set<String> acceptableNames =

              .filter(c -> acceptableNames.contains(c.getName()))

Also note that it's not strictly equivalent to the code you have (if it compiled), which adds the same client twice to the list if several users have the same name as the client.

Get WooCommerce product categories from WordPress

In my opinion this is the simplest solution

$orderby = 'name';
                $order = 'asc';
                $hide_empty = false ;
                $cat_args = array(
                    'orderby'    => $orderby,
                    'order'      => $order,
                    'hide_empty' => $hide_empty,

                $product_categories = get_terms( 'product_cat', $cat_args );

                if( !empty($product_categories) ){
                    echo '

                    foreach ($product_categories as $key => $category) {
                        echo '

                        echo '<a href="'.get_term_link($category).'" >';
                        echo $category->name;
                        echo '</a>';
                        echo '</li>';
                    echo '</ul>


X-UA-Compatible is set to IE=edge, but it still doesn't stop Compatibility Mode

I had the same issue after trying many combination I had this working note I have compatibility checked for intranet

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<head runat="server">

How to use CSS to surround a number with a circle?

The problem with most of the other answers here is you need to tweak the size of the outer container so that it is the perfect size based on the font size and number of characters to be displayed. If you are mixing 1 digit numbers and 4 digit numbers, it won't work. If the ratio between the font size and the circle size isn't perfect, you'll either end up with an oval or a small number vertically aligned at the top of a large circle. This should work fine for any amount of text and any size circle. Just set the width and line-height to the same value:

.numberCircle {_x000D_
    width: 120px;_x000D_
    line-height: 120px;_x000D_
    border-radius: 50%;_x000D_
    text-align: center;_x000D_
    font-size: 32px;_x000D_
    border: 2px solid #666;_x000D_
<div class="numberCircle">1</div>_x000D_
<div class="numberCircle">100</div>_x000D_
<div class="numberCircle">10000</div>_x000D_
<div class="numberCircle">1000000</div>

If you need to make the content longer or shorter, all you need to do is adjust the width of the container for a better fit.

See it on JSFiddle.

Error:Execution failed for task ':ProjectName:mergeDebugResources'. > Crunching Cruncher *some file* failed, see logs

I was getting the same error and it worked for me. Hope it helps.

As Niklas said, you have to update to the latest Gradle version.

My way to solve the error:

  1. Open your Android Studio (AS) program.
  2. Go to your build.gradle file in your project.
  3. Change:

    dependencies {
        classpath ''


    dependencies {
        classpath ''
  4. Sync your Android project with Gradle: enter image description here

  5. Clean your project.

  6. Rebuild your project.
  7. Done!

If its still not working:

  1. Close your Android Studio program and open it again.
  2. Try compiling the code.
  3. Done!

If you need more help, read the issue on Google Code!

How to join multiple lines of file names into one with custom delimiter?

ls produces one column output when connected to a pipe, so the -1 is redundant.

Here's another perl answer using the builtin join function which doesn't leave a trailing delimiter:

ls | perl -F'\n' -0777 -anE 'say join ",", @F'

The obscure -0777 makes perl read all the input before running the program.

sed alternative that doesn't leave a trailing delimiter

ls | sed '$!s/$/,/' | tr -d '\n'

Including another class in SCSS

Try this:

  1. Create a placeholder base class (%base-class) with the common properties
  2. Extend your class (.my-base-class) with this placeholder.
  3. Now you can extend %base-class in any of your classes (e.g. .my-class).

    %base-class {
       width: 80%;
       margin-left: 10%;
       margin-right: 10%;
    .my-base-class {
        @extend %base-class;
    .my-class {
        @extend %base-class;
        margin-bottom: 40px;

How to stop line breaking in vim

I personnally went for:

  • set wrap,
  • set linebreak
  • set breakindent
  • set showbreak=?.

Some explanation:

  • wrap option visually wraps line instead of having to scroll horizontally
  • linebreak is for wrapping long lines at a specific character instead of just anywhere when the line happens to be too long, like in the middle of a word. By default, it breaks on whitespace (word separator), but you can configure it with breakat. It also does NOT insert EOL in the file as the OP wanted.
  • breakat is the character where it will visually break the line. No need to modify it if you want to break at whitespace between two words.
  • breakindent enables to visually indent the line when it breaks.
  • showbreak enables to set the character which indicates this break.

See :h <keyword> within vim for more info.

Note that you don't need to modify textwidth nor wrapmargin if you go this route.

When to use @QueryParam vs @PathParam

REST may not be a standard as such, but reading up on general REST documentation and blog posts should give you some guidelines for a good way to structure API URLs. Most rest APIs tend to only have resource names and resource IDs in the path. Such as:


Some REST APIs use query strings for filtering, pagination and sorting, but Since REST isn't a strict standard I'd recommend checking some REST APIs out there such as github and stackoverflow and see what could work well for your use case.

I'd recommend putting any required parameters in the path, and any optional parameters should certainly be query string parameters. Putting optional parameters in the path will end up getting really messy when trying to write URL handlers that match different combinations.

DeprecationWarning: Buffer() is deprecated due to security and usability issues when I move my script to another server

new Buffer(number)            // Old
Buffer.alloc(number)          // New

new Buffer(string)            // Old
Buffer.from(string)           // New

new Buffer(string, encoding)  // Old
Buffer.from(string, encoding) // New

new Buffer(...arguments)      // Old
Buffer.from(...arguments)     // New

Note that Buffer.alloc() is also faster on the current Node.js versions than new Buffer(size).fill(0), which is what you would otherwise need to ensure zero-filling.

How do I get current scope dom-element in AngularJS controller?

The better and correct solution is to have a directive. The scope is the same, whether in the controller of the directive or the main controller. Use $element to do DOM operations. The method defined in the directive controller is accessible in the main controller.

Example, finding a child element:

var app = angular.module('myapp', []);
app.directive("testDir", function () {
    function link(scope, element) { 

    return {
        restrict: "AE", 
        link: link, 
            $scope.name2 = 'this is second name';
            var barGridSection = $element.find('#barGridSection'); //helps to find the child element.

app.controller('mainController', function ($scope) {
$'this is first name'

Laravel is there a way to add values to a request array

Based on my observations:

$request->request->add(['variable' => 'value']); will (mostly) work in POST, PUT & DELETE methods, because there is value(s) passed, one of those is _token. Like example below.

<form action="{{ route('process', $id) }}" method="POST">

public function process(Request $request, $id){
    $request->request->add(['id' => $id]);

But [below code] won't work because there is no value(s) passed, it doesn't really add.

<a href='{{ route('process', $id) }}'>PROCESS</a>

public function process(Request $request, $id){
    $request->request->add(['id' => $id]);

When using GET method you can either declare Request and assign value(s) on it directly. Like below:

public function process($id){
    $request = new Request(['id' => $id]);

Or you can use merge. This is better actually than $request->request->add(['variable' => 'value']); because can initialize, and add request values that will work for all methods (GET, POST, PUT, DELETE)

public function process(Request $request, $id){
    $request->merge(['id' => $id]);

Tag: laravel5.8.11

Month name as a string

As simple as this

mCalendar = Calendar.getInstance();    
String month = mCalendar.getDisplayName(Calendar.MONTH, Calendar.LONG, Locale.getDefault());

Calendar.LONG is to get the full name of the month and Calendar.SHORT gives the name in short. For eg: Calendar.LONG will return January Calendar.SHORT will return Jan

How to convert a DataTable to a string in C#?

If you have a single column in datatable than it's simple to change datatable to string.

DataTable results = MyMethod.GetResults();
if(results != null && results.Rows.Count > 0)  // Check datatable is null or not
  List<string> lstring = new List<string>();
  foreach(DataRow dataRow in dt.Rows)
  string mainresult = string.Join(",", lstring.ToArray()); // You can Use comma(,) or anything which you want. who connect the two string. You may leave space also.
Console.WriteLine (mainresult);

How to connect to SQL Server database from JavaScript in the browser?

You shouldn´t use client javascript to access databases for several reasons (bad practice, security issues, etc) but if you really want to do this, here is an example:

var connection = new ActiveXObject("ADODB.Connection") ;

var connectionstring="Data Source=<server>;Initial Catalog=<catalog>;User ID=<user>;Password=<password>;Provider=SQLOLEDB";

var rs = new ActiveXObject("ADODB.Recordset");

rs.Open("SELECT * FROM table", connection);


A better way to connect to a sql server would be to use some server side language like PHP, Java, .NET, among others. Client javascript should be used only for the interfaces.

And there are rumors of an ancient legend about the existence of server javascript, but this is another story. ;)

Java Multiple Inheritance

To reduce the complexity and simplify the language, multiple inheritance is not supported in java.

Consider a scenario where A, B and C are three classes. The C class inherits A and B classes. If A and B classes have same method and you call it from child class object, there will be ambiguity to call method of A or B class.

Since compile time errors are better than runtime errors, java renders compile time error if you inherit 2 classes. So whether you have same method or different, there will be compile time error now.

class A {  
    void msg() {
        System.out.println("From A");

class B {  
    void msg() {
        System.out.println("From B");

class C extends A,B { // suppose if this was possible
    public static void main(String[] args) {  
        C obj = new C();  
        obj.msg(); // which msg() method would be invoked?  

Django CharField vs TextField

I had an strange problem and understood an unpleasant strange difference: when I get an URL from user as an CharField and then and use it in html a tag by href, it adds that url to my url and that's not what I want. But when I do it by Textfield it passes just the URL that user entered. look at these: my website address:

CharField entery:

when clicking on it: http://myweb.com

TextField entery:

when clicking on it:

I must mention that the URL is saved exactly the same in DB by two ways but I don't know why result is different when clicking on them

How to shrink temp tablespace in oracle?

Oh My Goodness! Look at the size of my temporary table space! Or... how to shrink temporary tablespaces in Oracle.

Yes I ran a query to see how big my temporary tablespace is:

SQL> SELECT tablespace_name, file_name, bytes
2  FROM dba_temp_files WHERE tablespace_name like 'TEMP%';

TABLESPACE_NAME   FILE_NAME                                 BYTES
----------------- -------------------------------- --------------
TEMP              /the/full/path/to/temp01.dbf     13,917,200,000

The first question you have to ask is why the temporary tablespace is so large. You may know the answer to this off the top of your head. It may be due to a large query that you just run with a sort that was a mistake (I have done that more than once.) It may be due to some other exceptional circumstance. If that is the case then all you need to do to clean up is to shrink the temporary tablespace and move on in life.

But what if you don't know? Before you decide to shrink you may need to do some investigation into the causes of the large tablespace. If this happens on a regular basis then it is possible that your database just needs that much space.

The dynamic performance view


can be very useful in determining the cause.

Maybe you just don't care about the cause and you just need to shrink it. This is your third day on the job. The data in the database is only 200MiB if data and the temporary tablespace is 13GiB - Just shrink it and move on. If it grows again then we will look into the cause. In the mean time I am out of space on that disk volume and I just need the space back.

Let's take a look at shrinking it. It will depend a little on what version of Oracle you are running and how the temporary tablespace was set up.
Oracle will do it's best to keep you from making any horrendous mistakes so we will just try the commands and if they don't work we will shrink in a new way.

First let's try to shrink the datafile. If we can do that then we get back the space and we can worry about why it grew tomorrow.

SQL> alter database tempfile '/the/full/path/to/temp01.dbf' resize 256M; 
alter database tempfile '/the/full/path/to/temp01.dbf' resize 256M
ERROR at line 1:
ORA-03297: file contains used data beyond requested RESIZE value

Depending on the error message you may want to try this with different sizes that are smaller than the current site of the file. I have had limited success with this. Oracle will only shrink the file if the temporary tablespace is at the head of the file and if it is smaller than the size you specify. Some old Oracle documentation (they corrected this) said that you could issue the command and the error message would tell you what size you could shrink to. By the time I started working as a DBA this was not true. You just had to guess and re-run the command a bunch of times and see if it worked.

Alright. That didn't work. How about this.

SQL> alter tablespace YOUR_TEMP_TABLESPACE_NAME shrink space keep 256M;

If you are in 11g (Maybee in 10g too) this is it! If it works you may want to go back to the previous command and give it some more tries.

But what if that fails. If the temporary tablespace is the default temporary that was set up when the database was installed then you may need to do a lot more work. At this point I usually re-evaluate if I really need that space back. After all disk space only costs $X.XX a GiB. Usually I don't want to make changes like this during production hours. That means working at 2AM AGAIN! (Not that I really object to working at 2AM - it is just that... Well I like to sleep too. And my wife likes to have me at home at 2AM... not roaming the downtown streets at 4AM trying to remember where I parked my car 3 hours earlier. I have heard of that "telecommuting" thing. I just worry that I will get half way through and then my internet connectivity will fail - then I have to rush downtown to fix it all before folks show up in the morning to use the database.)

Ok... Back to the serious stuff... If the temporary tablespace you want to shrink is your default temporary tablespace, you will have to first create a new temporary tablespace, set it as the default temporary tablespace then drop your old default temporary tablespace and recreate it. Afterwords drop the second temporary table created.

2  TEMPFILE '/the/full/path/to/temp2_01.dbf' SIZE 5M REUSE

Tablespace created.


Database altered.


Tablespace dropped.

2  TEMPFILE '/the/full/path/to/temp01.dbf' SIZE 256M REUSE

Tablespace created.


Database altered.


Tablespace dropped.

Hopefully one of these things will help!

How can I upgrade NumPy?

Because you have multiple versions of NumPy installed.

Try pip uninstall numpy and pip list | grep numpy several times, until you see no output from pip list | grep numpy.

Then pip install numpy will get you the newest version of NumPy.

How to select distinct rows in a datatable and store into an array

var ValuetoReturn = (from Rows in YourDataTable.AsEnumerable()
select Rows["ColumnName"]).Distinct().ToList();

How to write loop in a Makefile?

You can use set -e as a prefix for the for-loop. Example:

    set -e; for a in 1 2 3; do /bin/false; echo $$a; done

make will exit immediately with an exit code <> 0.

Can multiple different HTML elements have the same ID if they're different elements?

Is it possible to have more than one student in a class having same Roll/Id no? In HTMLid attribute is like so. You may use same class for them. e.g:

<div class="a b c"></div>
<div class="a b c d"></div>

And so on.

How to reference a method in javadoc?

The general format, from the @link section of the javadoc documentation, is:

{@link package.class#member label}


Method in the same class:

/** See also {@link #myMethod(String)}. */
void foo() { ... }

Method in a different class, either in the same package or imported:

/** See also {@link MyOtherClass#myMethod(String)}. */
void foo() { ... }

Method in a different package and not imported:

/** See also {@link com.mypackage.YetAnotherClass#myMethod(String)}. */
void foo() { ... }

Label linked to method, in plain text rather than code font:

/** See also this {@linkplain #myMethod(String) implementation}. */
void foo() { ... }

A chain of method calls, as in your question. We have to specify labels for the links to methods outside this class, or we get getFoo().Foo.getBar().Bar.getBaz(). But these labels can be fragile during refactoring -- see "Labels" below.

 * A convenience method, equivalent to 
 * {@link #getFoo()}.{@link Foo#getBar() getBar()}.{@link Bar#getBaz() getBaz()}.
 * @return baz
public Baz fooBarBaz()


Automated refactoring may not affect labels. This includes renaming the method, class or package; and changing the method signature.

Therefore, provide a label only if you want different text than the default.

For example, you might link from human language to code:

/** You can also {@linkplain #getFoo() get the current foo}. */
void setFoo( Foo foo ) { ... }

Or you might link from a code sample with text different than the default, as shown above under "A chain of method calls." However, this can be fragile while APIs are evolving.

Type erasure and #member

If the method signature includes parameterized types, use the erasure of those types in the javadoc @link. For example:

int bar( Collection<Integer> receiver ) { ... }

/** See also {@link #bar(Collection)}. */
void foo() { ... }

Return the most recent record from ElasticSearch index

For information purpose, _timestamp is now deprecated since 2.0.0-beta2. Use date type in your mapping.

A simple date mapping JSON from date datatype doc:

  "mappings": {
     "my_type": {
        "properties": {
          "date": {
          "type": "date" 

You can also add a format field in date:

  "mappings": {
    "my_type": {
      "properties": {
        "date": {
          "type":   "date",
          "format": "yyy-MM-dd HH:mm:ss||yyyy-MM-dd||epoch_millis"

jQuery won't parse my JSON from AJAX query

Is your server sending data as Content-Type "*/json"? If not, modify the response headers accordingly. Sending "application/json" would be fine, for example.

Best practices for SQL varchar column length

VARCHAR(255) and VARCHAR(2) take exactly the same amount of space on disk! So the only reason to limit it is if you have a specific need for it to be smaller. Otherwise make them all 255.

Specifically, when doing sorting, larger column do take up more space, so if that hurts performance, then you need to worry about it and make them smaller. But if you only ever select 1 row from that table, then you can just make them all 255 and it won't matter.

See: What are the optimum varchar sizes for MySQL?

How to retrieve a user environment variable in CMake (Windows)

Getting variables into your CMake script

You can pass a variable on the line with the cmake invocation:

FOO=1 cmake

or by exporting a variable in BASH:

export FOO=1

Then you can pick it up in a cmake script using:


How to send push notification to web browser?

I suggest using pubnub. I tried using ServiceWorkers and PushNotification from the browser however, however when I tried it webviews did not support this.

How to include js file in another js file?

You need to write a document.write object:

document.write('<script type="text/javascript" src="file.js" ></script>');

and place it in your main javascript file

Python read JSON file and modify

I would like to present a modified version of Vadim's solution. It helps to deal with asynchronous requests to write/modify json file. I know it wasn't a part of the original question but might be helpful for others.

In case of asynchronous file modification os.remove(filename) will raise FileNotFoundError if requests emerge frequently. To overcome this problem you can create temporary file with modified content and then rename it simultaneously replacing old version. This solution works fine both for synchronous and asynchronous cases.

import os, json, uuid

filename = 'data.json'
with open(filename, 'r') as f:
    data = json.load(f)
    data['id'] = 134 # <--- add `id` value.
    # add, remove, modify content

# create randomly named temporary file to avoid 
# interference with other thread/asynchronous request
tempfile = os.path.join(os.path.dirname(filename), str(uuid.uuid4()))
with open(tempfile, 'w') as f:
    json.dump(data, f, indent=4)

# rename temporary file replacing old file
os.rename(tempfile, filename)

Access parent URL from iframe

You're correct. Subdomains are still considered separate domains when using iframes. It's possible to pass messages using postMessage(...), but other JS APIs are intentionally made inaccessible.

It's also still possible to get the URL depending on the context. See other answers for more details.

JavaScript Array splice vs slice

JavaScript Array splice() Method By Example

Example1 by tutsmake -Remove 2 elements from index 1

  var arr = [ "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten" ]; 


 console.log( arr ); 

Example-2 By tutsmake – Add new element from index 0 JavaScript

  var arr = [ "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten" ]; 


 console.log( arr );  

Example-3 by tutsmake – Add and Remove Elements in Array JavaScript

var months = ['Jan', 'March', 'April', 'June'];

months.splice(1, 0, 'Feb'); // add at index 1


months.splice(4, 1, 'May'); // replaces 1 element at index 4


How to remove underline from a link in HTML?

<style="text-decoration: none">

The above code will be enough.Just paste this into the link you want to remove underline from.

How to clear Tkinter Canvas?

Every canvas item is an object that Tkinter keeps track of. If you are clearing the screen by just drawing a black rectangle, then you effectively have created a memory leak -- eventually your program will crash due to the millions of items that have been drawn.

To clear a canvas, use the delete method. Give it the special parameter "all" to delete all items on the canvas (the string "all"" is a special tag that represents all items on the canvas):


If you want to delete only certain items on the canvas (such as foreground objects, while leaving the background objects on the display) you can assign tags to each item. Then, instead of "all", you could supply the name of a tag.

If you're creating a game, you probably don't need to delete and recreate items. For example, if you have an object that is moving across the screen, you can use the move or coords method to move the item.

The service cannot be started, either because it is disabled or because it has no enabled devices associated with it

This error can occur on anything that requires elevated privileges in Windows.

It happens when the "Application Information" service is disabled in Windows services. There are a few viruses that use this as an attack vector to prevent people from removing the virus. It also prevents people from installing software to remove viruses.

The normal way to fix this would be to run services.msc, or to go into Administrative Tools and run "Services". However, you will not be able to do that if the "Application Information" service is disabled.

Instead, reboot your computer into Safe Mode (reboot and press F8 until the Windows boot menu appears, select Safe Mode with Networking). Then run services.msc and look for services that are designated as "Disabled" in the Startup Type column. Change these "Disabled" services to "Automatic".

Make sure the "Application Information" service is set to a Startup Type of "Automatic".

When you are done enabling your services, click Ok at the bottom of the tool and reboot your computer back into normal mode. The problem should be resolved when Windows reboots.

COLLATION 'utf8_general_ci' is not valid for CHARACTER SET 'latin1'

In my case I created a database and gave the collation 'utf8_general_ci' but the required collation was 'latin1'. After changing my collation type to latin1_bin the error was gone.

What does 'COLLATE SQL_Latin1_General_CP1_CI_AS' do?

The COLLATE keyword specify what kind of character set and rules (order, confrontation rules) you are using for string values.

For example in your case you are using Latin rules with case insensitive (CI) and accent sensitive (AS)

You can refer to this Documentation

How to watch for form changes in Angular

If you are using FormBuilder, see @dfsq's answer.

If you are not using FormBuilder, there are two ways to be notified of changes.

Method 1

As discussed in the comments on the question, use an event binding on each input element. Add to your template:

<input type="text" class="form-control" required [ngModel]="model.first_name"

Then in your component:

doSomething(newValue) {
  model.first_name = newValue;

The Forms page has some additional information about ngModel that is relevant here:

The ngModelChange is not an <input> element event. It is actually an event property of the NgModel directive. When Angular sees a binding target in the form [(x)], it expects the x directive to have an x input property and an xChange output property.

The other oddity is the template expression, = $event. We're used to seeing an $event object coming from a DOM event. The ngModelChange property doesn't produce a DOM event; it's an Angular EventEmitter property that returns the input box value when it fires..

We almost always prefer [(ngModel)]. We might split the binding if we had to do something special in the event handling such as debounce or throttle the key strokes.

In your case, I suppose you want to do something special.

Method 2

Define a local template variable and set it to ngForm.
Use ngControl on the input elements.
Get a reference to the form's NgForm directive using @ViewChild, then subscribe to the NgForm's ControlGroup for changes:

<form #myForm="ngForm" (ngSubmit)="onSubmit()">
  <input type="text" ngControl="firstName" class="form-control" 
   required [(ngModel)]="model.first_name">
  <input type="text" ngControl="lastName" class="form-control" 
   required [(ngModel)]="model.last_name">

class MyForm {
  @ViewChild('myForm') form;
  ngAfterViewInit() {
      .subscribe(values => this.doSomething(values));
  doSomething(values) {


For more information on Method 2, see Savkin's video.

See also @Thierry's answer for more information on what you can do with the valueChanges observable (such as debouncing/waiting a bit before processing changes).

Why doesn't Java offer operator overloading?

Alternatives to Native Support of Java Operator Overloading

Since Java doesn't have operator overloading, here are some alternatives you can look into:

  1. Use another language. Both Groovy and Scala have operator overloading, and are based on Java.
  2. Use java-oo, a plugin that enables operator overloading in Java. Note that it is NOT platform independent. Also, it has many issues, and is not compatible with the latest releases of Java (i.e. Java 10). (Original StackOverflow Source)
  3. Use JNI, Java Native Interface, or alternatives. This allows you to write C or C++ (maybe others?) methods for use in Java. Of course this is also NOT platform independent.

If anyone is aware of others, please comment, and I will add it to this list.

Adding a parameter to the URL with JavaScript

A basic implementation which you'll need to adapt would look something like this:

function insertParam(key, value) {
    key = encodeURIComponent(key);
    value = encodeURIComponent(value);

    // kvp looks like ['key1=value1', 'key2=value2', ...]
    var kvp ='&');
    let i=0;

    for(; i<kvp.length; i++){
        if (kvp[i].startsWith(key + '=')) {
            let pair = kvp[i].split('=');
            pair[1] = value;
            kvp[i] = pair.join('=');

    if(i >= kvp.length){
        kvp[kvp.length] = [key,value].join('=');

    // can return this or...
    let params = kvp.join('&');

    // reload page with new params = params;

This is approximately twice as fast as a regex or search based solution, but that depends completely on the length of the querystring and the index of any match

the slow regex method I benchmarked against for completions sake (approx +150% slower)

function insertParam2(key,value)
    key = encodeURIComponent(key); value = encodeURIComponent(value);

    var s =;
    var kvp = key+"="+value;

    var r = new RegExp("(&|\\?)"+key+"=[^\&]*");

    s = s.replace(r,"$1"+kvp);

    if(!RegExp.$1) {s += (s.length>0 ? '&' : '?') + kvp;};

    //again, do what you will here = s;

How do I post button value to PHP?

Give them all a name that is the same

For example

<input type="button" value="a" name="btn" onclick="a" />
<input type="button" value="b" name="btn" onclick="b" />

Then in your php use:

$val = $_POST['btn']

Edit, as BalusC said; If you're not going to use onclick for doing any javascript (for example, sending the form) then get rid of it and use type="submit"

How to set dropdown arrow in spinner?

One simple way is to wrap your Spinner + Drop Down Arrow Image inside a Layout. Set the background of Spinner as transparent so that the default arrow icon gets hidden. Something like this:



            android:spinnerMode="dropdown" />

            android:src="@drawable/ic_chevron_down_blue" />


Here background.xml is a drawable to produce a box type background.

<shape xmlns:android="">
    <solid android:color="@android:color/transparent" />
    <corners android:radius="2dp" />
        android:color="#BDBDBD" />

The above code produces this type of a Spinner and icon.

Spinner with a custom drop down arrow

Excel VBA: AutoFill Multiple Cells with Formulas

Based on my Comment here is one way to get what you want done:

Start byt selecting any cell in your range and Press Ctrl + T

This will give you this pop up:

enter image description here

make sure the Where is your table text is correct and click ok you will now have:

enter image description here

Now If you add a column header in D it will automatically be added to the table all the way to the last row:

enter image description here

Now If you enter a formula into this column:

enter image description here

After you enter it, the formula will be auto filled all the way to last row:

enter image description here

Now if you add a new row at the next row under your table:

enter image description here

Once entered it will be resized to the width of your table and all columns with formulas will be added also:

enter image description here

Hope this solves your problem!

SQL Query - SUM(CASE WHEN x THEN 1 ELSE 0) for multiple columns

I think you should make a subquery to do grouping. In this case inner subquery returns few rows and you don't need a CASE statement. So I think this is going to be faster:

select Detail.ReceiptDate AS 'DATE',


select SentDate AS 'ReceiptDate', 
       count('TotalMailed') AS TotalMailed, 
       0 as TotalReturnMail, 
       0 as TraceReturnedMail
from MailDataExtract
where sentdate is not null

select MDE.ReturnMailDate AS 'ReceiptDate', 
       0 AS TotalMailed, 
       count(TotalReturnMail) as TotalReturnMail, 
       0 as TraceReturnedMail
from MailDataExtract MDE
where MDE.ReturnMailDate is not null
GROUP BY  MDE.ReturnMailDate


select MDE.ReturnMailDate AS 'ReceiptDate', 
       0 AS TotalMailed, 
       0 as TotalReturnMail, 
       count(TraceReturnedMail) as TraceReturnedMail

from MailDataExtract MDE
    inner join DTSharedData.dbo.ScanData SD 
        ON SD.ScanDataID = MDE.ReturnScanDataID
   where MDE.ReturnMailDate is not null AND SD.ReturnMailTypeID = 1
GROUP BY MDE.ReturnMailDate

) as Detail
GROUP BY Detail.ReceiptDate

how to run a winform from console application?

Here is the best method that I've found: First, set your projects output type to "Windows Application", then P/Invoke AllocConsole to create a console window.

internal static class NativeMethods
    internal static extern Boolean AllocConsole();

static class Program

    static void Main(string[] args) {
        if (args.Length == 0) {
            // run as windows app
            Application.Run(new Form1()); 
        } else {
            // run as console app
            Console.WriteLine("Hello World");


How can I add a Google search box to my website?

No need to embed! Just simply send the user to google and add the var in the search like this: (Remember, code might not work on this, so try in a browser if it doesn't.) Hope it works!

<textarea id="Blah"></textarea><button onclick="search()">Search</button>
function search() {
var Blah = document.getElementById("Blah").value;
location.replace("" + Blah + "");

    function search() {_x000D_
    var Blah = document.getElementById("Blah").value;_x000D_
    location.replace("" + Blah + "");_x000D_
<textarea id="Blah"></textarea><button onclick="search()">Search</button>

Elegant way to report missing values in a data.frame

My new favourite for (not too wide) data are methods from excellent naniar package. Not only you get frequencies but also patterns of missingness:


riskfactors %>%
  as_shadow_upset() %>%

enter image description here

It's often useful to see where the missings are in relation to non missing which can be achieved by plotting scatter plot with missings:

       aes(x = Ozone,
           y = Solar.R)) +

enter image description here

Or for categorical variables:

gg_miss_fct(x = riskfactors, fct = marital)

enter image description here

These examples are from package vignette that lists other interesting visualizations.

Enum ToString with user friendly strings

If you want something completely customizable, try out my solution here:

Basically, the post outlines how to attach Description attributes to each of your enums and provides a generic way to map from enum to description.

Application not picking up .css file (flask/python)

One more point to add on to this thread.

If you add an underscore in your .css file name, then it wouldn't work.

':app:lintVitalRelease' error when generating signed apk

Go to build.gradle(Module:app)

lintOptions {
    checkReleaseBuilds false
    // Or, if you prefer, you can continue to check for errors in release builds,
    // but continue the build even when errors are found:
    abortOnError false

PHP Redirect to another page after form submit

If your redirect is in PHP, nothing should be echoed to the user before the redirect instruction.

See header for more info.

Remember that header() must be called before any actual output is sent, either by normal HTML tags, blank lines in a file, or from PHP

Otherwise, you can use Javascript to redirect the user.

Just use

window.location = ""

Why is HttpContext.Current null?

try to implement Application_AuthenticateRequest instead of Application_Start.

this method has an instance for HttpContext.Current, unlike Application_Start (which fires very soon in app lifecycle, soon enough to not hold a HttpContext.Current object yet).

hope that helps.

How do I make a dotted/dashed line in Android?

The only thing that worked for me and I think it is the simplest way is using a Path with a paint object like this:

    Paint paintDash = new Paint();
    paintDash.setARGB(255, 0, 0, 0);
    paintDash.setPathEffect(new DashPathEffect(new float[]{10f,10f}, 0));
    Path pathDashLine = new Path();

Then onDraw(): (important call reset if you change those points between ondraw calls, cause Path save all the movements)

    pathDashLine.moveTo(porigenX, porigenY);
    c.drawPath(pathDashLine, paintDash);

iPhone - Get Position of UIView within entire UIWindow

In Swift:

let globalPoint = aView.superview?.convertPoint(aView.frame.origin, toView: nil)

Map isn't showing on Google Maps JavaScript API v3 when nested in a div tag

In my case I was getting the grey background and it turned out to be inclusion of a zoom value in the map options. Yup, makes no sense.

How to format html table with inline styles to look like a rendered Excel table?

This is quick-and-dirty (and not formally valid HTML5), but it seems to work -- and it is inline as per the question:

<table border='1' style='border-collapse:collapse'>

No further styling of <tr>/<td> tags is required (for a basic table grid).

matplotlib error - no module named tkinter

On CentOS 6.5 with python 2.7 I needed to do: yum install python27-tkinter

How to determine tables size in Oracle

If you don't have DBA rights then you can use user_segments table:

select bytes/1024/1024 MB from user_segments where segment_name='Table_name'

json.dumps vs flask.jsonify

The choice of one or another depends on what you intend to do. From what I do understand:

  • jsonify would be useful when you are building an API someone would query and expect json in return. E.g: The REST github API could use this method to answer your request.

  • dumps, is more about formating data/python object into json and work on it inside your application. For instance, I need to pass an object to my representation layer where some javascript will display graph. You'll feed javascript with the Json generated by dumps.

'uint32_t' does not name a type

The other answers assume that your compiler is C++11 compliant. That is fine if it is. But what if you are using an older compiler?

I picked up the following hack somewhere on the net. It works well enough for me:

  #if defined __UINT32_MAX__ or UINT32_MAX
  #include <inttypes.h>
  typedef unsigned char uint8_t;
  typedef unsigned short uint16_t;
  typedef unsigned long uint32_t;
  typedef unsigned long long uint64_t;

It is not portable, of course. But it might work for your compiler.

How to obtain the query string from the current URL with JavaScript?

Use to get everything after ? including ?


var url =;
url = url.replace("?", ''); // remove the ?
alert(url); //alerts ProjectID=462 is your case