Programs & Examples On #Webcontext

The entity type <type> is not part of the model for the current context

One other thing to check with your connection string - the model name. I was using two entity models, DB first. In the config I copied the entity connection for one, renamed it, and changed the connection string part. What I didn't change was the model name, so while the entity model generated correctly, when the context was initiated EF was looking in the wrong model for the entities.

Looks obvious written down, but there are four hours I won't get back.

Failed to load ApplicationContext for JUnit test of Spring controller

If you are using Maven, add the below config in your pom.xml:


With this config, you will be able to access xml files in WEB-INF folder. From Maven POM Reference: The testResources element block contains testResource elements. Their definitions are similar to resource elements, but are naturally used during test phases.

Invalid length for a Base-64 char array

The length of a base64 encoded string is always a multiple of 4. If it is not a multiple of 4, then = characters are appended until it is. A query string of the form ?name=value has problems when the value contains = charaters (some of them will be dropped, I don't recall the exact behavior). You may be able to get away with appending the right number of = characters before doing the base64 decode.

Edit 1

You may find that the value of UserNameToVerify has had "+"'s changed to " "'s so you may need to do something like so:

a = a.Replace(" ", "+");

This should get the length right;

int mod4 = a.Length % 4;
if (mod4 > 0 )
    a += new string('=', 4 - mod4);

Of course calling UrlEncode (as in LukeH's answer) should make this all moot.

Express.js Response Timeout

An update if one is using Express 4.2 then the timeout middleware has been removed so need to manually add it with

npm install connect-timeout

and in the code it has to be (Edited as per comment, how to include it in the code)

 var timeout = require('connect-timeout');

How do I make the scrollbar on a div only visible when necessary?

try this:

<div style='overflow:auto; width:400px;height:400px;'>here is some text</div>

Remove trailing newline from the elements of a string list

If you need to remove just trailing whitespace, you could use str.rstrip(), which should be slightly more efficient than str.strip():

>>> lst = ['this\n', 'is\n', 'a\n', 'list\n', 'of\n', 'words\n']
>>> [x.rstrip() for x in lst]
['this', 'is', 'a', 'list', 'of', 'words']
>>> list(map(str.rstrip, lst))
['this', 'is', 'a', 'list', 'of', 'words']

how to install Lex and Yacc in Ubuntu?

Use the synaptic packet manager in order to install yacc / lex. If you are feeling more comfortable doing this on the console just do:

sudo apt-get install bison flex

There are some very nice articles on the net on how to get started with those tools. I found the article from CodeProject to be quite good and helpful (see here). But you should just try and search for "introduction to lex", there are plenty of good articles showing up.

handling dbnull data in

You can use the IsDbNull function:

  If  IsDbNull(myItem("sID")) = False AndAlso myItem("sID")==sID Then
    // Do something
End If

Ansible: copy a directory content to another directory

I found a workaround for recursive copying from remote to remote :

- name: List files in /usr/share/easy-rsa
    path: /usr/share/easy-rsa
    recurse: yes
    file_type: any
  register: find_result

- name: Create the directories
    path: "{{ item.path | regex_replace('/usr/share/easy-rsa','/etc/easy-rsa') }}"
    state: directory
    mode: "{{ item.mode }}"
    - "{{ find_result.files }}"
    - item.isdir

- name: Copy the files
    src: "{{ item.path }}"
    dest: "{{ item.path | regex_replace('/usr/share/easy-rsa','/etc/easy-rsa') }}"
    remote_src: yes
    mode: "{{ item.mode }}"
    - "{{ find_result.files }}"
    - item.isdir == False

display: inline-block extra margin

For the record, that margin and padding resetting didn't do the trick for me, but this quote from one of the comments above turned out to be crucial and solved the issue for me: "If i put the divs on the same line it margin disappears."

HTML / CSS How to add image icon to input type="button"?

<button type="submit" style="background-color:transparent; border-color:transparent;"> 
  <img src="images/button/masuk.png" height="35"/>
<button type="reset" style="background-color:transparent; border-color:transparent;"> 
  <img src="images/button/reset.png" height="35"/>

I hope this helps you.

Returning the product of a list

Well if you really wanted to make it one line without importing anything you could do:

eval('*'.join(str(item) for item in list))

But don't.

Getting the current date in visual Basic 2008

If you need exact '/' delimiters, for example: 09/20/2013 rather than 09.20.2013, use escape sequence '/':

Dim regDate As Date = Date.Now()
Dim strDate As String = regDate.ToString("MM\/dd\/yyyy")

Is it possible to declare two variables of different types in a for loop?

Define a macro:

#define FOR( typeX,x,valueX,  typeY,y,valueY,  condition, increments) typeX x; typeY y; for(x=valueX,y=valueY;condition;increments)

FOR(int,i,0,  int,f,0.0,  i < 5, i++)

Just remember, your variable scopes will not be within the for loop this way either.

How to convert JSON string to array

If you are getting json string from URL using file_get_contents, then follow the steps:

$url = "http://localhost/rest/users";  //The url from where you are getting the contents
$response = (file_get_contents($url)); //Converting in json string
 $n = strpos($response, "[");
$response = substr_replace($response,"",0,$n+1);
$response = substr_replace($response, "" , -1,1);

No resource found that matches the given name: attr 'android:keyboardNavigationCluster'. when updating to Support Library 26.0.0

I had to change compileSdkVersion = 26 and buildToolsVersion = '26.0.1' in all my dependencies build.gradle files

How to clear textarea on click?

Here's a solution if you have dynamic data coming in from a database...
The 'data' variable represents database data.
If there is no data saved yet, the placeholder will show instead.
Once the user starts typing, the placeholder will disappear and they can then enter text.

Hope this helps someone!

// If data is NOT saved in the database
if (data == "") {
    var desc_text = "";
    var placeholder = "Please describe why";
// If data IS saved in the database
} else {
    var desc_text = data;
    var placeholder = "";

<textarea placeholder="'+placeholder+'">'+desc_text+'</textarea>

Run an OLS regression with Pandas Data Frame

I think you can almost do exactly what you thought would be ideal, using the statsmodels package which was one of pandas' optional dependencies before pandas' version 0.20.0 (it was used for a few things in pandas.stats.)

>>> import pandas as pd
>>> import statsmodels.formula.api as sm
>>> df = pd.DataFrame({"A": [10,20,30,40,50], "B": [20, 30, 10, 40, 50], "C": [32, 234, 23, 23, 42523]})
>>> result = sm.ols(formula="A ~ B + C", data=df).fit()
>>> print(result.params)
Intercept    14.952480
B             0.401182
C             0.000352
dtype: float64
>>> print(result.summary())
                            OLS Regression Results                            
Dep. Variable:                      A   R-squared:                       0.579
Model:                            OLS   Adj. R-squared:                  0.158
Method:                 Least Squares   F-statistic:                     1.375
Date:                Thu, 14 Nov 2013   Prob (F-statistic):              0.421
Time:                        20:04:30   Log-Likelihood:                -18.178
No. Observations:                   5   AIC:                             42.36
Df Residuals:                       2   BIC:                             41.19
Df Model:                           2                                         
                 coef    std err          t      P>|t|      [95.0% Conf. Int.]
Intercept     14.9525     17.764      0.842      0.489       -61.481    91.386
B              0.4012      0.650      0.617      0.600        -2.394     3.197
C              0.0004      0.001      0.650      0.583        -0.002     0.003
Omnibus:                          nan   Durbin-Watson:                   1.061
Prob(Omnibus):                    nan   Jarque-Bera (JB):                0.498
Skew:                          -0.123   Prob(JB):                        0.780
Kurtosis:                       1.474   Cond. No.                     5.21e+04

[1] The condition number is large, 5.21e+04. This might indicate that there are
strong multicollinearity or other numerical problems.

Finding repeated words on a string and counting the repetitions

You've got the hard work done. Now you can just use a Map to count the occurrences:

Map<String, Integer> occurrences = new HashMap<String, Integer>();

for ( String word : splitWords ) {
   Integer oldCount = occurrences.get(word);
   if ( oldCount == null ) {
      oldCount = 0;
   occurrences.put(word, oldCount + 1);

Using map.get(word) will tell you many times a word occurred. You can construct a new list by iterating through map.keySet():

for ( String word : occurrences.keySet() ) {
  //do something with word

Note that the order of what you get out of keySet is arbitrary. If you need the words to be sorted by when they first appear in your input String, you should use a LinkedHashMap instead.

How do I determine the current operating system with Node.js

Works fine for me

if (/^win/i.test(process.platform)) {
    // TODO: Windows
} else {
    // TODO: Linux, Mac or something else

The i modifier is used to perform case-insensitive matching.

How to quickly test some javascript code?

Install firebug: . You can use its console to test Javascript code. Google Chrome comes with Web Inspector in which you can do the same. IE and Safari also have Web Developer tools in which you can test Javascript.

System.Net.WebException: The remote name could not be resolved:

I had a similar issue when trying to access a service (old ASMX service). The call would work when accessing via an IP however when calling with an alias I would get the remote name could not be resolved.

Added the following to the config and it resolved the issue:

    <defaultProxy enabled="true">

how to access master page control from content page

I have a helper method for this in my System.Web.UI.Page class

protected T FindControlFromMaster<T>(string name) where T : Control
     MasterPage master = this.Master;
     while (master != null)
         T control = master.FindControl(name) as T;
         if (control != null)
             return control;

         master = master.Master;
     return null;

then you can access using below code.

Label lblStatus = FindControlFromMaster<Label>("lblStatus");
    lblStatus.Text = "something";

How to add a custom CA Root certificate to the CA Store used by pip in Windows?

Open Anaconda Navigator.

Go to File\Preferences.

Enable SSL verification Disable (not recommended)

or Enable and indicate SSL certificate path(Optional)

Update a package to a specific version:

Select Install on Top-Right

Select package click on tick

Mark for update

Mark for specific version installation

Click Apply

Abort trap 6 error in C

You are writing to memory you do not own:

int board[2][50]; //make an array with 3 columns  (wrong)
                  //(actually makes an array with only two 'columns')
for (i=0; i<num3+1; i++)
    board[2][i] = 'O';

Change this line:

int board[2][50]; //array with 2 columns (legal indices [0-1][0-49])


int board[3][50]; //array with 3 columns (legal indices [0-2][0-49])

When creating an array, the value used to initialize: [3] indicates array size.
However, when accessing existing array elements, index values are zero based.

For an array created: int board[3][50];
Legal indices are board[0][0]...board[2][49]

EDIT To address bad output comment and initialization comment

add an additional "\n" for formatting output:


  for (k=0; k<50;k++) {



  for (k=0; k<50;k++) {
  printf("\n");//at the end of every row, print a new line

Initialize board variable:

int board[3][50] = {0};//initialize all elements to zero

( array initialization discussion... )

Receiving JSON data back from HTTP request

Building on @Panagiotis Kanavos' answer, here's a working method as example which will also return the response as an object instead of a string:

using System.Text;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json; // Nuget Package

public static async Task<object> PostCallAPI(string url, object jsonObject)
        using (HttpClient client = new HttpClient())
            var content = new StringContent(jsonObject.ToString(), Encoding.UTF8, "application/json");
            var response = await client.PostAsync(url, content);
            if (response != null)
                var jsonString = await response.Content.ReadAsStringAsync();
                return JsonConvert.DeserializeObject<object>(jsonString);
    catch (Exception ex)
    return null;

Keep in mind that this is only an example and that you'd probably would like to use HttpClient as a shared instance instead of using it in a using-clause.

How to debug stored procedures with print statements?

Look at this Howto in the MSDN Documentation: Run the Transact-SQL Debugger - it's not with PRINT statements, but maybe it helps you anyway to debug your code.

This YouTube video: SQL Server 2008 T-SQL Debugger shows the use of the Debugger.

=> Stored procedures are written in Transact-SQL. This allows you to debug all Transact-SQL code and so it's like debugging in Visual Studio with defining breakpoints and watching the variables.

SQL : BETWEEN vs <= and >=

Logically there are no difference at all. Performance-wise there are -typically, on most DBMSes- no difference at all.

JDBC connection to MSSQL server in windows authentication mode

You need to add sqljdbc_auth.dll in your C:/windows/System32 folder. You can download it from .

Functions are not valid as a React child. This may happen if you return a Component instead of from render

In my case i forgot to add the () after the function name inside the render function of a react component

public render() {
       let ctrl = (
                <div className="aaa">

       return ctrl;

    private renderView() : JSX.Element {
        // some html

Changing the render method, as it states in the error message to

        <div className="aaa">

fixed the problem

How to make pylab.savefig() save image for 'maximized' window instead of default size

I did the same search time ago, it seems that he exact solution depends on the backend.

I have read a bunch of sources and probably the most useful was the answer by Pythonio here How to maximize a window using Python I adjusted the code and ended up with the function below. It works decently for me on windows, I mostly use Qt, where I use it quite often, while it is minimally tested with other backends.

Basically it consists in identifying the backend and calling the appropriate function. Note that I added a pause afterwards because I was having issues with some windows getting maximized and others not, it seems this solved for me.

def maximize(backend=None,fullscreen=False):
    """Maximize window independently on backend.
    Fullscreen sets fullscreen mode, that is same as maximized, but it doesn't have title bar (press key F to toggle full screen mode)."""
    if backend is None:
    mng = plt.get_current_fig_manager()

    if fullscreen:
        if backend == 'wxAgg':
        elif backend == 'Qt4Agg' or backend == 'Qt5Agg':
        elif backend == 'TkAgg':
            mng.window.state('zoomed') #works fine on Windows!
            print ("Unrecognized backend: ",backend) #not tested on different backends (only Qt)

    plt.pause(0.1) #this is needed to make sure following processing gets applied (e.g. tight_layout)

How do I insert a JPEG image into a python Tkinter window?

import tkinter as tk
from tkinter import ttk
from PIL import Image,  ImageTk
win = tk. Tk()
image1 = Image. open("Aoran. jpg")
image2 =  ImageTk. PhotoImage(image1)
image_label = ttk. Label(win , image =.image2) = 0 , y = 0)

make an html svg object also a clickable link

To accomplish this in all browsers you need to use a combination of @energee, @Richard and @Feuermurmel methods.

<a href="" style="display: block; z-index: 1;">
    <object data="" style="z-index: -1; pointer-events: none;" />


  • pointer-events: none; makes it work in Firefox.
  • display: block; gets it working in Chrome, and Safari.
  • z-index: 1; z-index: -1; makes it work in IE as well.

Android Emulator sdcard push error: Read-only file system

make sure that you have the correct permissions.

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

Change text from "Submit" on input tag

The value attribute on submit-type <input> elements controls the text displayed.

<input type="submit" class="like" value="Like" />

Converting Columns into rows with their respective data in sql server

i solved the query this way

    ca.ID, ca.[Name]
FROM [Emp2]
         ('ID' , cast(ID as varchar)),
         ('[Name]' , Name)

  ) as CA (ID, Name)

output look like

  ID     Name
------ --------------------------------------------------
ID     1
[Name] Joy
ID     2
[Name] jean
ID     4
[Name] paul

Bootstrap 3 - How to load content in modal body via AJAX?

This is actually super simple with just a little bit of added javascript. The link's href is used as the ajax content source. Note that for Bootstrap 3.* we set data-remote="false" to disable the deprecated Bootstrap load function.


// Fill modal with content from link href
$("#myModal").on("", function(e) {
    var link = $(e.relatedTarget);

Html (based on the official example):

<!-- Link trigger modal -->
<a href="remoteContent.html" data-remote="false" data-toggle="modal" data-target="#myModal" class="btn btn-default">
    Launch Modal

<!-- Default bootstrap modal example -->
<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      <div class="modal-body">
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>

Try it yourself:

"Uncaught Error: [$injector:unpr]" with angular after deployment

Add the $http, $scope services in the controller fucntion, sometimes if they are missing these errors occur.

What is the best way to programmatically detect porn images?

Nude.js based on the whitepaper by Rigan Ap-apid from De La Salle University.

smooth scroll to top

Here is my proposal implemented with ES6

const scrollToTop = () => {
  const c = document.documentElement.scrollTop || document.body.scrollTop;
  if (c > 0) {
    window.scrollTo(0, c - c / 8);

Tip: for slower motion of the scrolling, increase the hardcoded number 8. The bigger the number - the smoother/slower the scrolling.

Convert String to Integer in XSLT 1.0

Adding to jelovirt's answer, you can use number() to convert the value to a number, then round(), floor(), or ceiling() to get a whole integer.


<xsl:variable name="MyValAsText" select="'5.14'"/>
<xsl:value-of select="number($MyValAsText) * 2"/> <!-- This outputs 10.28 -->
<xsl:value-of select="floor($MyValAsText)"/> <!-- outputs 5 -->
<xsl:value-of select="ceiling($MyValAsText)"/> <!-- outputs 6 -->
<xsl:value-of select="round($MyValAsText)"/> <!-- outputs 5 -->

What are libtool's .la file for?

It is a textual file that includes a description of the library.

It allows libtool to create platform-independent names.

For example, libfoo goes to:

Under Linux:

/lib/       # Symlink to shared object
/lib/     # Symlink to shared object
/lib/ # Shared object
/lib/libfoo.a        # Static library
/lib/       # 'libtool' library

Under Cygwin:

/lib/libfoo.dll.a    # Import library
/lib/libfoo.a        # Static library
/lib/       # libtool library
/bin/cygfoo_1.dll    # DLL

Under Windows MinGW:

/lib/libfoo.dll.a    # Import library
/lib/libfoo.a        # Static library
/lib/       # 'libtool' library
/bin/foo_1.dll       # DLL

So is the only file that is preserved between platforms by libtool allowing to understand what happens with:

  • Library dependencies
  • Actual file names
  • Library version and revision

Without depending on a specific platform implementation of libraries.

wget: unable to resolve host address `http'

remove the http or https from wget . this worked fine for me.

How to access nested elements of json object using getJSONArray method

You can try this:

JSONObject result = new JSONObject("Your string here").getJSONObject("result");
JSONObject map = result.getJSONObject("map");
JSONArray entries= map.getJSONArray("entry");

I hope this helps.

How to install Visual C++ Build tools?

The current version (2019/03/07) is Build Tools for Visual Studio 2017. It's an online installer, you need to include at least the individual components:

  • VC++ 2017 version xx.x tools
  • Windows SDK to use standard libraries.

What are the alternatives now that the Google web search API has been deprecated?

Google Custom Search (as advocated in the top rated answers) works well, but is very expensive, compared to its competitors (below) or compared to other Google API's. It has a small free tier (100 queries/day) and a very high price of $5 per 1000 query.

They offer the option to upgrade to Site Search, which has slightly better prices, but that is meant for searching one site (your own), so it is really something quite different - not an upgrade.

The main alternatives seem to be:

Bing Search API
Which has a free tier of 5000q/month, and prices starting at 5 query per penny, and no hard limit.

UPDATE: At the end of 2016 this API was shutdown in favour of its Azure counterpart "Cognitive Services Bing Search API":

See here for a pricing chart, which starts at US$3/m for 1,000 transactions. Unless I'm missing something it is quite expensive.

Yahoo BOSS Search API
UPDATE: Was discontinued on March 31, 2016.
With prices starting at about 12 queries/penny for whole web searches.

And some I haven't heard of before:
[discontinued - as pointed out below]

There is a bit of discussion of some of these on this SO post.
[got closed for being off-topic and is now gone]

AppendChild() is not a function javascript

In this

var div = '<div>top div</div>';

"div" is not a DOM object,is just a string,and string has no string.appendChild.

Here are some references that may help you on appendChild method:

<div id="div1">
<p id="p1">This is a paragraph.</p>
<p id="p2">This is another paragraph.</p>

var para = document.createElement("p");
var node = document.createTextNode("This is new.");

var element = document.getElementById("div1");
</script> Broken pipe

Error message suggests that the client has closed the connection while the server is still trying to write out a response.

Refer to this link for more details:

Testing if a site is vulnerable to Sql Injection

A login page isn't the only part of a database-driven website that interacts with the database.

Any user-editable input which is used to construct a database query is a potential entry point for a SQL injection attack. The attacker may not necessarily login to the site as an admin through this attack, but can do other things. They can change data, change server settings, etc. depending on the nature of the application's interaction with the database.

Appending a ' to an input is usually a pretty good test to see if it generates an error or otherwise produces unexpected behavior on the site. It's an indication that the user input is being used to build a raw query and the developer didn't expect a single quote, which changes the query structure.

Keep in mind that one page may be secure against SQL injection while another one may not. The login page, for example, may be hardened against such attacks. But a different page elsewhere in the site might be wide open. So, for example, if one wanted to login as an admin then one can use the SQL injection on that other page to change the admin password. Then return to the perfectly non-SQL-injectable login page and login as the admin.

Change a branch name in a Git repo

Assuming you're currently on the branch you want to rename:

git branch -m newname

This is documented in the manual for git-branch, which you can view using

man git-branch


git help branch

Specifically, the command is

git branch (-m | -M) [<oldbranch>] <newbranch>

where the parameters are:

       The name of an existing branch to rename.

       The new name for an existing branch. The same restrictions as for <branchname> apply.

<oldbranch> is optional, if you want to rename the current branch.

How can I dismiss the on screen keyboard?

As in Flutter everything is a widget, I decided to wrap the SystemChannels.textInput.invokeMethod('TextInput.hide'); and the FocusScope.of(context).requestFocus(FocusNode()); approach in a short utility module with a widget and a mixin in it.

With the widget, you can wrap any widget (very convenient when using a good IDE support) with the KeyboardHider widget:

class SimpleWidget extends StatelessWidget {
  Widget build(BuildContext context) {
    return KeyboardHider(
      /* Here comes a widget tree that eventually opens the keyboard,
       * but the widget that opened the keyboard doesn't necessarily
       * takes care of hiding it, so we wrap everything in a
       * KeyboardHider widget */
      child: Container(),

With the mixin, you can trigger hiding the keyboard from any state or widget upon any interaction:

class SimpleWidget extends StatefulWidget {
  _SimpleWidgetState createState() => _SimpleWidgetState();

class _SimpleWidgetState extends State<SimpleWidget> with KeyboardHiderMixin {
  Widget build(BuildContext context) {
    return RaisedButton(
      onPressed: () {
        // Hide the keyboard:
        // Do other stuff, for example:
        // Update the state, make an HTTP request, ...

Just create a keyboard_hider.dart file and the widget and mixin are ready to use:

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

/// Mixin that enables hiding the keyboard easily upon any interaction or logic
/// from any class.
abstract class KeyboardHiderMixin {
  void hideKeyboard({
    BuildContext context,
    bool hideTextInput = true,
    bool requestFocusNode = true,
  }) {
    if (hideTextInput) {
    if (context != null && requestFocusNode) {

/// A widget that can be used to hide the text input that are opened by text
/// fields automatically on tap.
/// Delegates to [KeyboardHiderMixin] for hiding the keyboard on tap.
class KeyboardHider extends StatelessWidget with KeyboardHiderMixin {
  final Widget child;

  /// Decide whether to use
  /// `SystemChannels.textInput.invokeMethod('TextInput.hide');`
  /// to hide the keyboard
  final bool hideTextInput;
  final bool requestFocusNode;

  /// One of hideTextInput or requestFocusNode must be true, otherwise using the
  /// widget is pointless as it will not even try to hide the keyboard.
  const KeyboardHider({
    Key key,
    @required this.child,
    this.hideTextInput = true,
    this.requestFocusNode = true,
  })  : assert(child != null),
        assert(hideTextInput || requestFocusNode),
        super(key: key);

  Widget build(BuildContext context) {
    return GestureDetector(
      behavior: HitTestBehavior.opaque,
      onTap: () {
          context: context,
          hideTextInput: hideTextInput,
          requestFocusNode: requestFocusNode,
      child: child,

Purge or recreate a Ruby on Rails database

From the command line run

rake db:migrate:reset

Install Android App Bundle on device

Installing the aab directly from the device, I couldn't find a way for that.

But there is a way to install it through your command line using the following documentation You can install apk to a device through BundleTool

According to "@Albert Vila Calvo" comment he noted that to install bundletools using HomeBrew use brew install bundletool

You can now install extract apks from aab file and install it to a device

Extracting apk files from through the next command

java -jar bundletool-all-0.3.3.jar build-apks --bundle=bundle.aab --output=app.apks --ks=my-release-key.keystore --ks-key-alias=alias --ks-pass=pass:password


  • --bundle -> Android Bundle .aab file
  • --output -> Destination and file name for the generated apk file
  • --ks -> Keystore file used to generate the Android Bundle
  • --ks-key-alias -> Alias for keystore file
  • --ks-pass -> Password for Alias file (Please note the 'pass' prefix before password value)

Then you will have a file with extension .apks So now you need to install it to a device

java -jar bundletool-all-0.6.0.jar install-apks --adb=/android-sdk/platform-tools/adb --apks=app.apks


  • --adb -> Path to adb file
  • --apks -> Apks file need to be installed

Hexadecimal string to byte array in C

The best way I know:

int hex2bin_by_zibri(char *source_str, char *dest_buffer)
  char *line = source_str;
  char *data = line;
  int offset;
  int read_byte;
  int data_len = 0;

  while (sscanf(data, " %02x%n", &read_byte, &offset) == 1) {
    dest_buffer[data_len++] = read_byte;
    data += offset;
  return data_len;

The function returns the number of converted bytes saved in dest_buffer. The input string can contain spaces and mixed case letters.

"01 02 03 04 ab Cd eF garbage AB"

translates to dest_buffer containing 01 02 03 04 ab cd ef

and also "01020304abCdeFgarbageAB"

translates as before.

Parsing stops at the first "error".

How do I call an Angular 2 pipe with multiple arguments?

Extended from : user3777549

Multi-value filter on one set of data(reference to title key only)


<div *ngFor='let item of items | filtermulti: [{title:["mr","ms"]},{first:["john"]}]' >
 Hello {{item.first}} !


args.forEach(function (filterobj) {
    let filterkey = Object.keys(filterobj)[0];
    let filtervalue = filterobj[filterkey];
    myobjects.forEach(function (objectToFilter) {

      if (!filtervalue.some(x=>x==objectToFilter[filterkey]) && filtervalue != "") {
        // object didn't match a filter value so remove it from array via filter
        returnobjects = returnobjects.filter(obj => obj !== objectToFilter);

selecting from multi-index pandas

You can also use query which is very readable in my opinion and straightforward to use:

import pandas as pd

df = pd.DataFrame({'A': [1, 2, 3, 4], 'B': [10, 20, 50, 80], 'C': [6, 7, 8, 9]})
df = df.set_index(['A', 'B'])

A B    
1 10  6
2 20  7
3 50  8
4 80  9

For what you had in mind you can now simply do:

df.query('A == 1')

A B    
1 10  6

You can also have more complex queries using and

df.query('A >= 1 and B >= 50')

A B    
3 50  8
4 80  9

and or

df.query('A == 1 or B >= 50')

A B    
1 10  6
3 50  8
4 80  9

You can also query on different index levels, e.g.

df.query('A == 1 or C >= 8')

will return

A B    
1 10  6
3 50  8
4 80  9

If you want to use variables inside your query, you can use @:

b_threshold = 20
c_threshold = 8

df.query('B >= @b_threshold and C <= @c_threshold')

A B    
2 20  7
3 50  8

Regex to accept alphanumeric and some special character in Javascript?


/^[ A-Za-z0-9_@./#&+-]*$/

You can also use the character class \w to replace A-Za-z0-9_

Send values from one form to another form

Declare a public string in form1

public string getdata;

In button of form1

form2 frm= new form2();

To send data to form1 you can try any event and code following in that event

form1 frm= new form1();
form1.getdata="some string to be sent to form1";

Now after closing of form2 and opening of form1, you can use returned data in getdata string.

iterating through json object javascript

My problem was actually a problem of bad planning with the JSON object rather than an actual logic issue. What I ended up doing was organize the object as follows, per a suggestion from user2736012.

        "trunk_id" : "1",
        "message": "This is just a JSON Test"
        "trunk_id" : "2",
        "message": "This is a test of a bit longer text. Hopefully this will at the very least create 3 lines and trigger us to go on to another box. So we can test multi-box functionality, too."

At that point, I was able to do a fairly simple for loop based on the total number of objects.

var totalMessages = Object.keys(messages.dialog.trunks).length;

    for ( var i = 0; i < totalMessages; i++)
        console.log("ID: " + messages.dialog.trunks[i].trunk_id + " Message " + messages.dialog.trunks[i].message);

My method for getting totalMessages is not supported in all browsers, though. For my project, it actually doesn't matter, but beware of that if you choose to use something similar to this.

How to get UTC timestamp in Ruby?

What good is a timestamp with its granularity given in seconds? I find it much more practical working with Heck, you may even throw a to_s.sub('.','') to get rid of the decimal point, or perform a typecast like this: Integer(1e6*

How can I get the current page name in WordPress?

<?php wp_title(''); ?>

This worked for me.

If I understand correctly, you want to get the page name on a page that has post entries.

nodejs get file name from absolute path?

var path = require("path");
var filepath = "C:\\Python27\\ArcGIS10.2\\python.exe";
var name = path.parse(filepath).name;
// returns

Above code returns the name of the file without extension, if you need the name with extention use

var path = require("path");
var filepath = "C:\\Python27\\ArcGIS10.2\\python.exe";
var name = path.basename(filepath);
// returns

Pandas: Return Hour from Datetime Column Directly

You can use a lambda expression, e.g:

sales['time_hour'] = sales.timestamp.apply(lambda x: x.hour)

How do I get the information from a meta tag with JavaScript?

The other answers should probably do the trick, but this one is simpler and does not require jQuery:


The original question used an RDFa tag with a property="" attribute. For the normal HTML <meta name="" …> tags you could use something like:


How to browse localhost on Android device?

I used ngrok but now it need registration and it also has a connections request limit. Now I'm using LocalTunnel and so far it's much better.

dplyr change many data types

You can use the standard evaluation version of mutate_each (which is mutate_each_) to change the column classes:

dat %>% mutate_each_(funs(factor), l1) %>% mutate_each_(funs(as.numeric), l2)

Write string to output stream

You can create a PrintStream wrapping around your OutputStream and then just call it's print(String):

final OutputStream os = new FileOutputStream("/tmp/out");
final PrintStream printStream = new PrintStream(os);

How to remove commits from a pull request

So do the following ,

Lets say your branch name is my_branch and this has the extra commits.

  1. git checkout -b my_branch_with_extra_commits (Keeping this branch saved under a different name)
  2. gitk (Opens git console)
  3. Look for the commit you want to keep. Copy the SHA of that commit to a notepad.
  4. git checkout my_branch
  5. gitk (This will open the git console )
  6. Right click on the commit you want to revert to (State before your changes) and click on "reset branch to here"
  7. Do a git pull --rebase origin branch_name_to _merge_to
  8. git cherry-pick <SHA you copied in step 3. >

Now look at the local branch commit history and make sure everything looks good.

Https Connection Android

This is what I am doing. It simply doesn't check the certificate anymore.

// always verify the host - dont check for certificate
final static HostnameVerifier DO_NOT_VERIFY = new HostnameVerifier() {
    public boolean verify(String hostname, SSLSession session) {
        return true;

 * Trust every server - dont check for any certificate
private static void trustAllHosts() {
    // Create a trust manager that does not validate certificate chains
    TrustManager[] trustAllCerts = new TrustManager[] { new X509TrustManager() {
        public[] getAcceptedIssuers() {
            return new[] {};

        public void checkClientTrusted(X509Certificate[] chain,
                String authType) throws CertificateException {

        public void checkServerTrusted(X509Certificate[] chain,
                String authType) throws CertificateException {
    } };

    // Install the all-trusting trust manager
    try {
        SSLContext sc = SSLContext.getInstance("TLS");
        sc.init(null, trustAllCerts, new;
    } catch (Exception e) {


    HttpURLConnection http = null;

    if (url.getProtocol().toLowerCase().equals("https")) {
        HttpsURLConnection https = (HttpsURLConnection) url.openConnection();
        http = https;
    } else {
        http = (HttpURLConnection) url.openConnection();

What are functional interfaces used for in Java 8?

An interface with only one abstract method is called Functional Interface. It is not mandatory to use @FunctionalInterface, but it’s best practice to use it with functional interfaces to avoid addition of extra methods accidentally. If the interface is annotated with @FunctionalInterface annotation and we try to have more than one abstract method, it throws compiler error.

package com.akhi;
    public interface FucnctionalDemo {

      void letsDoSomething();
      //void letsGo();      //invalid because another abstract method does not allow
      public String toString();    // valid because toString from Object 
      public boolean equals(Object o); //valid

      public static int sum(int a,int b)   // valid because method static
            return a+b;
        public default int sub(int a,int b)   //valid because method default
            return a-b;

Java 8 Lambda filter by Lists

Look this:

List<Client> result = clients
    .filter(c -> 

What do the different readystates in XMLHttpRequest mean, and how can I use them?

kieron's answer contains w3schools ref. to which nobody rely , bobince's answer gives link , which actually tells native implementation of IE ,

so here is the original documentation quoted to rightly understand what readystate represents :

The XMLHttpRequest object can be in several states. The readyState attribute must return the current state, which must be one of the following values:

UNSENT (numeric value 0)
The object has been constructed.

OPENED (numeric value 1)
The open() method has been successfully invoked. During this state request headers can be set using setRequestHeader() and the request can be made using the send() method.

HEADERS_RECEIVED (numeric value 2)
All redirects (if any) have been followed and all HTTP headers of the final response have been received. Several response members of the object are now available.

LOADING (numeric value 3)
The response entity body is being received.

DONE (numeric value 4)
The data transfer has been completed or something went wrong during the transfer (e.g. infinite redirects).

Please Read here : W3C Explaination Of ReadyState

Display a tooltip over a button using Windows Forms

Using the form designer:

  • Drag the ToolTip control from the Toolbox, onto the form.
  • Select the properties of the control you want the tool tip to appear on.
  • Find the property 'ToolTip on toolTip1' (the name may not be toolTip1 if you changed it's default name).
  • Set the text of the property to the tool tip text you would like to display.

You can set also the tool tip programatically using the following call:

this.toolTip1.SetToolTip(this.targetControl, "My Tool Tip");

Vertical Alignment of text in a table cell

CSS {vertical-align: top;} or html Attribute {valign="top"}

.table td, 
.table th {
    border: 1px solid #161b21;
    text-align: left;
    padding: 8px;
    width: 250px;
    height: 100px;
    /* style for table */

.table-body-text {
  vertical-align: top;
<table class="table">
      <th valign="top">Title 1</th>
      <th valign="top">Title 2</th>
      <td class="table-body-text">text</td>
      <td class="table-body-text">text</td>

For table vertical-align we have 2 options.

  1. is to use css {vertical-align: top;}
  1. another way is to user attribute "valign" and the property should be "top" {valign="top"}

Android: Clear the back stack

logout.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK); logout.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

Highest Salary in each department

If you just want to get the highest salary from that table, by department:


Angular CLI Error: The serve command requires to be run in an Angular project, but a project definition could not be found

This error may be occur when we are in wrong use cd command to change your directory. It's not very evident from the above comment that which specific command is giving this error so this answer is based on assumption that you are running ng serve outside the root folder/actual project folder. That's why it's giving error because cli commands require conf & build files to run the cli build.

These should be the steps:
npm install -g @angular/cli  //corrected from 'angular-cli'
ng new projectname
cd projectname
ng serve
open http://localhost:4200

Responsive iframe using Bootstrap

Option 3

To update current iframe

$("iframe").wrap('<div class="embed-responsive embed-responsive-16by9"/>');

Wait for a process to finish

All these solutions are tested in Ubuntu 14.04:

Solution 1 (by using ps command): Just to add up to Pierz answer, I would suggest:

while ps axg | grep -vw grep | grep -w process_name > /dev/null; do sleep 1; done

In this case, grep -vw grep ensures that grep matches only process_name and not grep itself. It has the advantage of supporting the cases where the process_name is not at the end of a line at ps axg.

Solution 2 (by using top command and process name):

while [[ $(awk '$12=="process_name" {print $0}' <(top -n 1 -b)) ]]; do sleep 1; done

Replace process_name with the process name that appears in top -n 1 -b. Please keep the quotation marks.

To see the list of processes that you wait for them to be finished, you can run:

while : ; do p=$(awk '$12=="process_name" {print $0}' <(top -n 1 -b)); [[ $b ]] || break; echo $p; sleep 1; done

Solution 3 (by using top command and process ID):

while [[ $(awk '$1=="process_id" {print $0}' <(top -n 1 -b)) ]]; do sleep 1; done

Replace process_id with the process ID of your program.

Difference between angle bracket < > and double quotes " " while including header files in C++?

It's compiler dependent. That said, in general using " prioritizes headers in the current working directory over system headers. <> usually is used for system headers. From to the specification (Section 6.10.2):

A preprocessing directive of the form

  # include <h-char-sequence> new-line

searches a sequence of implementation-defined places for a header identified uniquely by the specified sequence between the < and > delimiters, and causes the replacement of that directive by the entire contents of the header. How the places are specified or the header identified is implementation-defined.

A preprocessing directive of the form

  # include "q-char-sequence" new-line

causes the replacement of that directive by the entire contents of the source file identified by the specified sequence between the " delimiters. The named source file is searched for in an implementation-defined manner. If this search is not supported, or if the search fails, the directive is reprocessed as if it read

  # include <h-char-sequence> new-line

with the identical contained sequence (including > characters, if any) from the original directive.

So on most compilers, using the "" first checks your local directory, and if it doesn't find a match then moves on to check the system paths. Using <> starts the search with system headers.

jQuery return ajax result into outside variable

'async': false says it's depreciated. I did notice if I run console.log('test1'); on ajax success, then console.log('test2'); in normal js after the ajax function, test2 prints before test1 so the issue is an ajax call has a small delay, but doesn't stop the rest of the function to get results. The variable simply, was not set "yet", so you need to delay the next function.

function runPHP(){
    var input = document.getElementById("input1");
    var result = 'failed to run php';

    $.ajax({ url: '/test.php',
        type: 'POST',
        data: {action: 'test'},
        success: function(data) {
            result = data;

    }, 1000);

on test.php (incase you need to test this function)

function test(){
    print 'ran php';

if(isset($_POST['action']) && !empty($_POST['action'])) {
    $action = htmlentities($_POST['action']);
    switch($action) {
        case 'test' : test();break;

Python method for reading keypress?

It's really late now but I made a quick script which works for Windows, Mac and Linux, simply by using each command line:

import os, platform

def close():
    if platform.system() == "Windows":
        print("Press any key to exit . . .")
    elif platform.system() == "Linux":
        os.system("read -n1 -r -p \"Press any key to exit . . .\" key")
    elif platform.system() == "Darwin":
        print("Press any key to exit . . .")
        os.system("read -n 1 -s -p \"\"")

It uses only inbuilt functions, and should work for all three (although I've only tested Windows and Linux...).

Your branch is ahead of 'origin/master' by 3 commits

Use these 4 simple commands

Step 1 : git checkout <branch_name>

This is obvious to go into that branch.

Step 2 : git pull -s recursive -X theirs

Take remote branch changes and replace with their changes if conflict arise. Here if you do git status you will get something like this your branch is ahead of 'origin/master' by 3 commits.

Step 3 : git reset --hard origin/<branch_name>

Step 4 : git fetch

Hard reset your branch.


When to use NSInteger vs. int

You usually want to use NSInteger when you don't know what kind of processor architecture your code might run on, so you may for some reason want the largest possible integer type, which on 32 bit systems is just an int, while on a 64-bit system it's a long.

I'd stick with using NSInteger instead of int/long unless you specifically require them.

NSInteger/NSUInteger are defined as *dynamic typedef*s to one of these types, and they are defined like this:

typedef long NSInteger;
typedef unsigned long NSUInteger;
typedef int NSInteger;
typedef unsigned int NSUInteger;

With regard to the correct format specifier you should use for each of these types, see the String Programming Guide's section on Platform Dependencies

A good Sorted List for Java

To test the efficiancy of earlier awnser by Konrad Holl, I did a quick comparison with what I thought would be the slow way of doing it:

package util.collections;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;

 * @author Earl Bosch
 * @param <E> Comparable Element
public class SortedList<E extends Comparable> implements List<E> {

     * The list of elements
    private final List<E> list = new ArrayList();

    public E first() {
        return list.get(0);

    public E last() {
        return list.get(list.size() - 1);

    public E mid() {
        return list.get(list.size() >>> 1);

    public void clear() {

    public boolean add(E e) {
        return true;

    public int size() {
        return list.size();

    public boolean isEmpty() {
        return list.isEmpty();

    public boolean contains(Object obj) {
        return list.contains((E) obj);

    public Iterator<E> iterator() {
        return list.iterator();

    public Object[] toArray() {
        return list.toArray();

    public <T> T[] toArray(T[] arg0) {
        return list.toArray(arg0);

    public boolean remove(Object obj) {
        return list.remove((E) obj);

    public boolean containsAll(Collection<?> c) {
        return list.containsAll(c);

    public boolean addAll(Collection<? extends E> c) {

        return true;

    public boolean addAll(int index, Collection<? extends E> c) {
        throw new UnsupportedOperationException("Not supported.");

    public boolean removeAll(Collection<?> c) {
        return list.removeAll(c);

    public boolean retainAll(Collection<?> c) {
        return list.retainAll(c);

    public E get(int index) {
        return list.get(index);

    public E set(int index, E element) {
        throw new UnsupportedOperationException("Not supported.");

    public void add(int index, E element) {
        throw new UnsupportedOperationException("Not supported.");

    public E remove(int index) {
        return list.remove(index);

    public int indexOf(Object obj) {
        return list.indexOf((E) obj);

    public int lastIndexOf(Object obj) {
        return list.lastIndexOf((E) obj);

    public ListIterator<E> listIterator() {
        return list.listIterator();

    public ListIterator<E> listIterator(int index) {
        return list.listIterator(index);

    public List<E> subList(int fromIndex, int toIndex) {
        throw new UnsupportedOperationException("Not supported.");


Turns out its about twice as fast! I think its because of SortedLinkList slow get - which make's it not a good choice for a list.

Compared times for same random list:

  • SortedLinkList : 15731.460
  • SortedList : 6895.494
  • ca.odell.glazedlists.SortedList : 712.460
  • org.apache.commons.collections4.TreeList : 3226.546

Seems glazedlists.SortedList is really fast...

How to apply CSS page-break to print a table with lots of rows?

If you know about how many you want on a page, you could always do this. It will start a new page after every 20th item.

.row-item:nth-child(20n) {
    page-break-after: always;
    page-break-inside: avoid;

What is the purpose of the HTML "no-js" class?

The no-js class gets removed by a javascript script, so you can modify/display/hide things using css if js is disabled.

Using Python, find anagrams for a list of words

There are multiple solutions to this problem:

  1. Classic approach

    First, let's consider what defines an anagram: two words are anagrams of each other if they consist of the same set of letters and each letter appears exactly the same number or time in both words. This is basically a histogram of letters count of each word. This is a perfect use case for collections.Counter data structure (see docs). The algorithms is as follows:

    • Build a dictionary where keys would be histograms and values would be lists of words that have this histogram.
    • For each word build it's histogram and add it to the list that corresponds to this histogram.
    • Output list of dictionary values.

    Here is the code:

    from collections import Counter, defaultdict
    def anagram(words):
        anagrams = defaultdict(list)
        for word in words:
            histogram = tuple(Counter(word).items()) # build a hashable histogram
        return list(anagrams.values())
    keywords = ("hi", "hello", "bye", "helol", "abc", "cab", 
                    "bac", "silenced", "licensed", "declines")

    Note that constructing Counter is O(l), while sorting each word is O(n*log(l)) where l is the length of the word.

  2. Solving anagrams using prime numbers

    This is a more advanced solution, that relies on the "multiplicative uniqueness" of prime numbers. You can refer to this SO post: Comparing anagrams using prime numbers, and here is a sample python implementation.

Pythonic way to find maximum value and its index in a list?

I would suggest a very simple way:

import numpy as np
l = [10, 22, 8, 8, 11]

Hope it helps.

Angular: 'Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays'

As the error messages stated, ngFor only supports Iterables such as Array, so you cannot use it for Object.


private extractData(res: Response) {
  let body = <Afdelingen[]>res.json();
  return body || {};       // here you are return an object


private extractData(res: Response) {
  let body = <Afdelingen[]>res.json().afdelingen;    // return array from json file
  return body || [];     // also return empty array if there is no data

Append values to query string

This is even more frustrating because now (.net 5) MS have marked many (all) of their methods that take a string instead of a Uri as obsolete.

Anyway, probably a better way to manipulate relative Uris is to give it what it wants:

var requestUri = new Uri("x://x").MakeRelativeUri(
   new UriBuilder("x://x") { Path = path, Query = query }.Uri);

You can use the other answers to actually build the query string.

npm - EPERM: operation not permitted on Windows

Restarting VsCode solved it for me!

How to limit depth for recursive file list?

Make use of find's options

There is actually no exec of /bin/ls needed;

Find has an option that does just that:

find . -maxdepth 2 -type d -ls

To see only the one level of subdirectories you are interested in, add -mindepth to the same level as -maxdepth:

find . -mindepth 2 -maxdepth 2 -type d -ls

Use output formatting

When the details that get shown should be different, -printf can show any detail about a file in custom format; To show the symbolic permissions and the owner name of the file, use -printf with %M and %u in the format.

I noticed later you want the full ownership information, which includes the group. Use %g in the format for the symbolic name, or %G for the group id (like also %U for numeric user id)

find . -mindepth 2 -maxdepth 2 -type d -printf '%M %u %g %p\n'

This should give you just the details you need, for just the right files.

I will give an example that shows actually different values for user and group:

$ sudo find /tmp -mindepth 2 -maxdepth 2 -type d -printf '%M %u %g %p\n'
drwx------ www-data  www-data /tmp/user/33
drwx------ octopussy root     /tmp/user/126
drwx------ root      root     /tmp/user/0
drwx------ siegel    root     /tmp/user/1000
drwxrwxrwt root      root     /tmp/systemd-[...].service-HRUQmm/tmp

(Edited for readability: indented, shortened last line)

Notes on performance

Although the execution time is mostly irrelevant for this kind of command, increase in performance is large enough here to make it worth pointing it out:

Not only do we save creating a new process for each name - a huge task - the information does not even need to be read, as find already knows it.

Replace whitespaces with tabs in linux

Using sed:

T=$(printf "\t")
sed "s/[[:blank:]]\+/$T/g"


sed "s/[[:space:]]\+/$T/g"

Reliable way to convert a file to a byte[]

Not to repeat what everyone already have said but keep the following cheat sheet handly for File manipulations:

  1. System.IO.File.ReadAllBytes(filename);
  2. File.Exists(filename)
  3. Path.Combine(folderName, resOfThePath);
  4. Path.GetFullPath(path); // converts a relative path to absolute one
  5. Path.GetExtension(path);

Giving a border to an HTML table row, <tr>

adding border-spacing: 0rem 0.5rem; creates a space for each cell (td, th) items on its bottom while leaving no space between the cells{
        border-collapse: separate;
        border-spacing: 0rem 0.5rem;
    } thead tr.border-row the, tbody tr.border-row td, tbody tr.border-row th{
        border-top: 1px solid #EAEAEA;
        border-bottom: 1px solid #EAEAEA;
        vertical-align: middle;
        white-space: nowrap;
        font-size: 0.875rem;
    } thead tr.border-row th:first-child, tbody tr.border-row td:first-child{
        border-left: 1px solid #EAEAEA;
    } thead tr.border-row th:last-child, tbody tr.border-row td:last-child{
        border-right: 1px solid #EAEAEA;

How do I check if a string contains another string in Swift?

You don't need to write any custom code for this. Starting from the 1.2 version Swift has already had all the methods you need:

  • getting string length: count(string);
  • checking if string contains substring: contains(string, substring);
  • checking if string starts with substring: startsWith(string, substring)
  • and etc.

How can I draw circle through XML Drawable - Android?

no need for the padding or the corners.

here's a sample:

<shape xmlns:android="" android:shape="oval" >
    <gradient android:startColor="#FFFF0000" android:endColor="#80FF00FF"

based on :

What primitive data type is time_t?

You could always use something like mktime to create a known time (midnight, last night) and use difftime to get a double-precision time difference between the two. For a platform-independant solution, unless you go digging into the details of your libraries, you're not going to do much better than that. According to the C spec, the definition of time_t is implementation-defined (meaning that each implementation of the library can define it however they like, as long as library functions with use it behave according to the spec.)

That being said, the size of time_t on my linux machine is 8 bytes, which suggests a long int or a double. So I did:

int main()
        printf ("%ld\n", time(NULL));
        printf ("%f\n", time(NULL));
    return 0;

The time given by the %ld increased by one each step and the float printed 0.000 each time. If you're hell-bent on using printf to display time_ts, your best bet is to try your own such experiment and see how it work out on your platform and with your compiler.

Url to a google maps page to show a pin given a latitude / longitude?

You should be able to do something like this:,120.780512

Some more info on the query parameters available at this location

Here's another link to an SO thread

What is the command for cut copy paste a file from one directory to other directory

E:>move "blogger code.txt" d:/"blogger code.txt"

    1 file(s) moved.

"blogger code.txt" is a file name

The file move from E: drive to D: drive

Unable to import a module that is definitely installed

I had this exact problem, but none of the answers above worked. It drove me crazy until I noticed that sys.path was different after I had imported from the parent project. It turned out that I had used importlib to write a little function in order to import a file not in the project hierarchy. Bad idea: I forgot that I had done this. Even worse, the import process mucked with the sys.path--and left it that way. Very bad idea.

The solution was to stop that, and simply put the file I needed to import into the project. Another approach would have been to put the file into its own project, as it needs to be rebuilt from time to time, and the rebuild may or may not coincide with the rebuild of the main project.

Integer division: How do you produce a double?

Type Casting Is The Only Way

May be you will not do it explicitly but it will happen.

Now, there are several ways we can try to get precise double value (where num and denom are int type, and of-course with casting)-

  1. with explicit casting:
  • double d = (double) num / denom;
  • double d = ((double) num) / denom;
  • double d = num / (double) denom;
  • double d = (double) num / (double) denom;

but not double d = (double) (num / denom);

  1. with implicit casting:
  • double d = num * 1.0 / denom;
  • double d = num / 1d / denom;
  • double d = ( num + 0.0 ) / denom;
  • double d = num; d /= denom;

but not double d = num / denom * 1.0;
and not double d = 0.0 + ( num / denom );

Now if you are asking- Which one is better? explicit? or implicit?

Well, lets not follow a straight answer here. Simply remember- We programmers don't like surprises or magics in a source. And we really hate Easter Eggs.

Also, an extra operation will definitely not make your code more efficient. Right?

iOS 11, 12, and 13 installed certificates not trusted automatically (self signed)

I've been struggling with this for 3 days now while attempting to connect to a local API running Laravel valet. I finally figured it out. In my case I had to drag and drop over the LaravelValetCASelfSigned.pem file from ~/.config/valet/CA/LaravelValetCASelfSigned.pem

After verifying the installing within the simulator I had to go to Settings > About > Certificate Trust Settings > and Enable the Laravel Valet VA Self Signed CN

Finally working!!!

How to animate CSS Translate

According to CanIUse you should have it with multiple prefixes.


How to clear a notification in Android

Use the following code to cancel a Notification:

NotificationManager notificationManager = (NotificationManager)getSystemService(Context.NOTIFICATION_SERVICE);

In this code there is alway the same id used for notifications. If you have different notifications that need to be canceled you have to save the ids that you used to create the Notification.

How do I create a link using javascript?

With JavaScript

  1. var a = document.createElement('a');
    a.innerHTML = desiredText;
    // apend the anchor to the body
    // of course you can append it almost to any other dom element
  2. document.getElementsByTagName('body')[0].innerHTML += '<a href="'+desiredLink+'">'+desiredText+'</a>';

    or, as suggested by @travis :

    document.getElementsByTagName('body')[0].innerHTML +=;
  3. <script type="text/javascript">
    //note that this case can be used only inside the "body" element
    document.write('<a href="'+desiredLink+'">'+desiredText+'</a>');

With JQuery

  1. $('<a href="'+desiredLink+'">'+desiredText+'</a>').appendTo($('body'));
  2. $('body').append($('<a href="'+desiredLink+'">'+desiredText+'</a>'));
  3. var a = $('<a />');

In all the above examples you can append the anchor to any element, not just to the 'body', and desiredLink is a variable that holds the address that your anchor element points to, and desiredText is a variable that holds the text that will be displayed in the anchor element.

Any way to break if statement in PHP?

proper way to do this :

    if( !process_x() ){
        throw new Exception('process_x failed');

    /* do a lot of other things */

    if( !process_y() ){
        throw new Exception('process_y failed');

    /* do a lot of other things */

    if( !process_z() ){
        throw new Exception('process_z failed');

    /* do a lot of other things */
    /* SUCCESS */
}catch(Exception $ex){

After reading some of the comments, I realized that exception handling doesn't always makes sense for normal flow control. For normal control flow it is better to use "If else":

  if( process_x() && process_y() && process_z() ) {
    // all processes successful
    // do something
  } else {
    //one of the processes failed
}catch(Exception ex){
  // one of the processes raised an exception

You can also save the process return values in variables and then check in the failure/exception blocks which process has failed.

SOAP vs REST (differences)

First of all: officially, the correct question would be web services + WSDL + SOAP vs REST.

Because, although the web service, is used in the loose sense, when using the HTTP protocol to transfer data instead of web pages, officially it is a very specific form of that idea. According to the definition, REST is not "web service".

In practice however, everyone ignores that, so let's ignore it too

There are already technical answers, so I'll try to provide some intuition.

Let's say you want to call a function in a remote computer, implemented in some other programming language (this is often called remote procedure call/RPC). Assume that function can be found at a specific URL, provided by the person who wrote it. You have to (somehow) send it a message, and get some response. So, there are two main questions to consider.

  • what is the format of the message you should send
  • how should the message be carried back and forth

For the first question, the official definition is WSDL. This is an XML file which describes, in detailed and strict format, what are the parameters, what are their types, names, default values, the name of the function to be called, etc. An example WSDL here shows that the file is human-readable (but not easily).

For the second question, there are various answers. However, the only one used in practice is SOAP. Its main idea is: wrap the previous XML (the actual message) into yet another XML (containing encoding info and other helpful stuff), and send it over HTTP. The POST method of the HTTP is used to send the message, since there is always a body.

The main idea of this whole approach is that you map a URL to a function, that is, to an action. So, if you have a list of customers in some server, and you want to view/update/delete one, you must have 3 URLS:

  • myapp/read-customer and in the body of the message, pass the id of the customer to be read.
  • myapp/update-customer and in the body, pass the id of the customer, as well as the new data
  • myapp/delete-customer and the id in the body

The REST approach sees things differently. A URL should not represent an action, but a thing (called resource in the REST lingo). Since the HTTP protocol (which we are already using) supports verbs, use those verbs to specify what actions to perform on the thing.

So, with the REST approach, customer number 12 would be found on URL myapp/customers/12. To view the customer data, you hit the URL with a GET request. To delete it, the same URL, with a DELETE verb. To update it, again, the same URL with a POST verb, and the new content in the request body.

For more details about the requirements that a service has to fulfil to be considered truly RESTful, see the Richardson maturity model. The article gives examples, and, more importantly, explains why a (so-called) SOAP service, is a level-0 REST service (although, level-0 means low compliance to this model, it's not offensive, and it is still useful in many cases).

support FragmentPagerAdapter holds reference to old fragments

I faced the same issue but my ViewPager was inside a TopFragment which created and set an adapter using setAdapter(new FragmentPagerAdapter(getChildFragmentManager())).

I fixed this issue by overriding onAttachFragment(Fragment childFragment) in the TopFragment like this:

public void onAttachFragment(Fragment childFragment) {
    if (childFragment instanceof OnboardingDiamondsFragment) {
        mChildFragment = (ChildFragment) childFragment;


As known already (see answers above), when the childFragmentManager recreate itself, it also create the fragments which were inside the viewPager.
The important part is that after that, he calls onAttachFragment and now we have a reference to the new recreated fragment!

Hope this will help anyone getting this old Q like me :)

Is there a better alternative than this to 'switch on type'?

With JaredPar's answer in the back of my head, I wrote a variant of his TypeSwitch class that uses type inference for a nicer syntax:

class A { string Name { get; } }
class B : A { string LongName { get; } }
class C : A { string FullName { get; } }
class X { public string ToString(IFormatProvider provider); }
class Y { public string GetIdentifier(); }

public string GetName(object value)
    string name = null;
        .Case((C x) => name = x.FullName)
        .Case((B x) => name = x.LongName)
        .Case((A x) => name = x.Name)
        .Case((X x) => name = x.ToString(CultureInfo.CurrentCulture))
        .Case((Y x) => name = x.GetIdentifier())
        .Default((x) => name = x.ToString());
    return name;

Note that the order of the Case() methods is important.

Get the full and commented code for my TypeSwitch class. This is a working abbreviated version:

public static class TypeSwitch
    public static Switch<TSource> On<TSource>(TSource value)
        return new Switch<TSource>(value);

    public sealed class Switch<TSource>
        private readonly TSource value;
        private bool handled = false;

        internal Switch(TSource value)
            this.value = value;

        public Switch<TSource> Case<TTarget>(Action<TTarget> action)
            where TTarget : TSource
            if (!this.handled && this.value is TTarget)
                action((TTarget) this.value);
                this.handled = true;
            return this;

        public void Default(Action<TSource> action)
            if (!this.handled)

How to make bootstrap 3 fluid layout without horizontal scrollbar

This is what worked for me. I added a style inline to remove the small margin on the right. I don't really like to do inline styling, but this lone style attribute in my html makes it easy for me to remember about the hack-job spliced into my otherwise well separated code. It also eliminates the concern of my external styles loading before or after the bootstrap default stylesheet.

<div class="row" style="margin-right:0px;">
  <div class="col-md-6">
  <div class="col-md-6">

How do I download a file from the internet to my linux server with Bash

I guess you could use curl and wget, but since Oracle requires you to check of some checkmarks this will be painfull to emulate with the tools mentioned. You would have to download the page with the license agreement and from looking at it figure out what request is needed to get to the actual download.

Of course you could simply start a browser, but this might not qualify as 'from the command line'. So you might want to look into lynx, a text based browser.

How to overwrite files with Copy-Item in PowerShell

As I understand Copy-Item -Exclude then you are doing it correct. What I usually do, get 1'st, and then do after, so what about using Get-Item as in

Get-Item -Path $copyAdmin -Exclude $exclude |
Copy-Item  -Path $copyAdmin -Destination $AdminPath -Recurse -force

PHP - Merging two arrays into one array (also Remove Duplicates)

The best solution above faces a problem when using the same associative keys, array_merge() will merge array elements together when they have the same NON-NUMBER key, so it is not suitable for the following case


If you are able output your value to the keys of your arrays instead (e.g ->pluck('name', 'id')->toArray() in Eloquent), you can use the following merge method instead

array_keys(array_merge($a1, $a2))

Basically what the code does is it utilized the behavior of array_merge() to get rid of duplicated keys and return you a new array with keys as array elements, hope it helps

`&mdash;` or `&#8212;` is there any difference in HTML output?

Could be that using the numeral code is more universal, as it's a direct reference to a character in the html entity table, but I guess they both work everywhere. The first notation is just massively easier to remember for a lot of characters.

How do I use Assert.Throws to assert the type of the exception?

You can now use the ExpectedException attributes, e.g.

 ExpectedMessage="You can't do that!"]
public void MethodA_WithNull_ThrowsInvalidOperationException()

How to avoid Sql Query Timeout

While I would be tempted to blame my issues - I'm getting the same error with my query, which is much, much bigger and involves a lot of loops - on the network, I think this is not the case.

Unfortunately it's not that simple. Query runs for 3+ hours before getting that error and apparently it crashes at the same time if it's just a query in SSMS and a job on SQL Server (did not look into details of that yet, so not sure if it's the same error; definitely same spot, though).

So just in case someone comes here with similar problem, this thread:

suggest that it may equally well be a hardware issue or actual timeout.

My loops aren't even (they depend on sales level in given month) in terms of time required for each, so good month takes about 20 mins to calculate (query looks at 4 years).

That way it's entirely possible I need to optimise my query. I would even say it's likely, as some changes I did included new tables, which are heaps... So another round of indexing my data before tearing into VM config and hardware tests.

Being aware that this is old question: I'm on SQL Server 2012 SE, SSMS is 2018 Beta and VM the SQL Server runs on has exclusive use of 132GB of RAM (30% total), 8 cores, and 2TB of SSD SAN.

How can I run Android emulator for Intel x86 Atom without hardware acceleration on Windows 8 for API 21 and 19?

You need "VT-x supported processor" at least to run Android emulator with Hardware acceleration.

If you have enabled or installed "Hyper-V" in your windows 8 then please remove it and disable the "Hyper threading" and enable "Virtualization".

Ping all addresses in network, windows

for /l %%a in (254, -1, 1) do ( 
    for /l %%b in (1, 1, 254) do (
        for %%c in (20, 168) do (
            for %%e in (172, 192) do (
                ping /n 1 %%e.%%c.%%b.%%a>>ping.txt

Select values of checkbox group with jQuery

With map in instead of each it is possible to avoid the array creation step:

var checkedCheckboxesValues = 
        .map(function() {
            return $(this).val();

From the map() page of the docs:

Pass each element in the current matched set through a function, producing a new jQuery object containing the return values

get() turns those values into an array.

How do I add an integer value with javascript (jquery) to a value that's returning a string?

Parse int is the tool you should use here, but like any tool it should be used correctly. When using parseInt you should always use the radix parameter to ensure the correct base is used

var currentValue = parseInt($("#replies").text(),10);

How to hide a status bar in iOS?

What helped me is this (changing plist file):

  1. set Status bar is initially hidden = YES
  2. add row: View controller-based status bar appearance = NO

Hide StatusBar - plist settings

How to list active connections on PostgreSQL?

Oh, I just found that command on PostgreSQL forum:

SELECT * FROM pg_stat_activity;

How to transfer some data to another Fragment?

This is how you use bundle:

Bundle b = new Bundle();
b.putInt("id", id);
Fragment frag= new Fragment();

retrieve value from bundle:

 bundle = getArguments();
 if (bundle != null) {
    id = bundle.getInt("id");

How to kill all processes with a given partial name?

Sounds bad?

 pkill `pidof myprocess`


# kill all java processes
pkill `pidof java`

Java HTTPS client certificate authentication

I've connected to bank with two-way SSL (client and server certificate) with Spring Boot. So describe here all my steps, hope it helps someone (simplest working solution, I've found):

  1. Generate sertificate request:

    • Generate private key:

      openssl genrsa -des3 -passout pass:MY_PASSWORD -out user.key 2048
    • Generate certificate request:

      openssl req -new -key user.key -out user.csr -passin pass:MY_PASSWORD

    Keep user.key (and password) and send certificate request user.csr to bank for my sertificate

  2. Receive 2 certificate: my client root certificate clientId.crt and bank root certificate: bank.crt

  3. Create Java keystore (enter key password and set keystore password):

    openssl pkcs12 -export -in clientId.crt -inkey user.key -out keystore.p12 -name clientId -CAfile ca.crt -caname root

    Don't pay attention on output: unable to write 'random state'. Java PKCS12 keystore.p12 created.

  4. Add into keystore bank.crt (for simplicity I've used one keystore):

    keytool -import -alias banktestca -file banktestca.crt -keystore keystore.p12 -storepass javaops

    Check keystore certificates by:

    keytool -list -keystore keystore.p12
  5. Ready for Java code:) I've used Spring Boot RestTemplate with add org.apache.httpcomponents.httpcore dependency:

    public RestTemplate sslRestTemplate() throws Exception {
      char[] storePassword = appProperties.getSslStorePassword().toCharArray();
      URL keyStore = new URL(appProperties.getSslStore());
      SSLContext sslContext = new SSLContextBuilder()
            .loadTrustMaterial(keyStore, storePassword)
      // use storePassword twice (with key password do not work)!!
            .loadKeyMaterial(keyStore, storePassword, storePassword) 
      // Solve "Certificate doesn't match any of the subject alternative names"
      SSLConnectionSocketFactory socketFactory = new SSLConnectionSocketFactory(sslContext, NoopHostnameVerifier.INSTANCE);
      CloseableHttpClient client = HttpClients.custom().setSSLSocketFactory(socketFactory).build();
      HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory(client);
      RestTemplate restTemplate = new RestTemplate(factory);
      // restTemplate.setMessageConverters(List.of(new Jaxb2RootElementHttpMessageConverter()));
      return restTemplate;

powershell mouse move does not prevent idle mode

I've added a notification that you can easily enable / disable just setting its variable to $true or $false. Also the mouse cursor moves 1 px right and then 1 px left so it basically stays in the same place even after several iterations.

# Lines needed for the notification
Add-Type -AssemblyName System.Windows.Forms 
$isNotificationOn = $true

$secondsBetweenMouseMoves = 6
$Pos = [System.Windows.Forms.Cursor]::Position
$PosDelta = 1
$logFilename = "previousMouseMoverAction.txt"
$errorLogFilename = "mouseMoverLog.txt"

if (!(Test-Path "$PSScriptRoot\$logFilename")) {
   New-Item -path $PSScriptRoot -name $logFilename -type "file" -value "right"
   Write-Host "Warning: previousMouseMoverAction.txt missing, created a new one."

$previousPositionChangeAction = Get-Content -Path $PSScriptRoot\$logFilename

if ($previousPositionChangeAction -eq "left") {
    $PosDelta = 1
    Set-Content -Path $PSScriptRoot\$logFilename -Value 'right'
} else {
    $PosDelta = -1
    Set-Content -Path $PSScriptRoot\$logFilename -Value 'left'

for ($i = 0; $i -lt $secondsBetweenMouseMoves; $i++) {
    [System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point((($Pos.X) + $PosDelta) , $Pos.Y)
    if ($isNotificationOn) {
        # Sending a notification to the user
        $global:balloon = New-Object System.Windows.Forms.NotifyIcon
        $path = (Get-Process -id $pid).Path
        $balloon.Icon = [System.Drawing.Icon]::ExtractAssociatedIcon($path) 
        $balloon.BalloonTipIcon = [System.Windows.Forms.ToolTipIcon]::Warning 
        $balloon.BalloonTipText = 'I have just moved your cheese...'
        $balloon.BalloonTipTitle = "Attention, $Env:USERNAME" 
        $balloon.Visible = $true 

SystemError: Parent module '' not loaded, cannot perform relative import

If you go one level up in running the script in the command line of your bash shell, the issue will be resolved. To do this, use cd .. command to change the working directory in which your script will be running. The result should look like this:

[username@localhost myProgram]$

rather than this:

[username@localhost app]$

Once you are there, instead of running the script in the following format:


Change it to this:

python3 app/

This process can be repeated once again one level up depending on the structure of your Tree diagram. Please also include the compilation command line that is giving you that mentioned error message.

How to convert DataSet to DataTable

A DataSet already contains DataTables. You can just use:

DataTable firstTable = dataSet.Tables[0];

or by name:

DataTable customerTable = dataSet.Tables["Customer"];

Note that you should have using statements for your SQL code, to ensure the connection is disposed properly:

using (SqlConnection conn = ...)
    // Code here...

How to load up CSS files using Javascript?

Here's the "old school" way of doing it, which hopefully works across all browsers. In theory, you would use setAttribute unfortunately IE6 doesn't support it consistently.

var cssId = 'myCss';  // you could encode the css path itself to generate id..
if (!document.getElementById(cssId))
    var head  = document.getElementsByTagName('head')[0];
    var link  = document.createElement('link');   = cssId;
    link.rel  = 'stylesheet';
    link.type = 'text/css';
    link.href = ''; = 'all';

This example checks if the CSS was already added so it adds it only once.

Put that code into a javascript file, have the end-user simply include the javascript, and make sure the CSS path is absolute so it is loaded from your servers.


Here is an example that uses plain JavaScript to inject a CSS link into the head element based on the filename portion of the URL:

<script type="text/javascript">
var file = location.pathname.split( "/" ).pop();

var link = document.createElement( "link" );
link.href = file.substr( 0, file.lastIndexOf( "." ) ) + ".css";
link.type = "text/css";
link.rel = "stylesheet"; = "screen,print";

document.getElementsByTagName( "head" )[0].appendChild( link );

Insert the code just before the closing head tag and the CSS will be loaded before the page is rendered. Using an external JavaScript (.js) file will cause a Flash of unstyled content (FOUC) to appear.

This certificate has an invalid issuer Apple Push Services

In Apple's Developer's portal, add a new certificate, and when asked "What type of certificate do you need?" choose "WorldWide developer relations certificate". Generate the new certificate, download and install. The moment you do that, you will no longer see the message you have described.

The certificate can be downloaded from the following page: You can choose one of the following two certificates: "WWDR Certificate (Expiring 02/07/23)" or "WWDR Certificate (Expiring 02/14/16)"

php artisan migrate throwing [PDO Exception] Could not find driver - Using Laravel

Please check your Laravel .env file also. Make sure DB_CONNECTION=mysql, otherwise it won't work with MySQL. It tried to load something else.

changing source on html5 video tag

Using JavaScript and jQuery:

<script src="js/jquery.js"></script>
<video id="vid" width="1280" height="720" src="v/myvideo01.mp4" controls autoplay></video>
function chVid(vid) {
<div onclick="chVid('v/myvideo02.mp4')">See my video #2!</div>

Android ListView not refreshing after notifyDataSetChanged


Try this in onPause() method of Activity class.

Getting value of select (dropdown) before change

How about using a custom jQuery event with an angular watch type interface;

// adds a custom jQuery event which gives the previous and current values of an input on change
(function ($) {
    // new event type tl_change
    jQuery.event.special.tl_change = {
        add: function (handleObj) {
            // use mousedown and touchstart so that if you stay focused on the
            // element and keep changing it, it continues to update the prev val
                .on('mousedown.tl_change touchstart.tl_change', handleObj.selector, focusHandler)
                .on('change.tl_change', handleObj.selector, function (e) {
                // use an anonymous funciton here so we have access to the
                // original handle object to call the handler with our args
                var $el = $(this);
                // call our handle function, passing in the event, the previous and current vals
                // override the change event name to our name
                e.type = "tl_change";
                handleObj.handler.apply($el, [e, $'tl-previous-val'), $el.val()]);
        remove: function (handleObj) {
                .off('mousedown.tl_change touchstart.tl_change', handleObj.selector, focusHandler)
                .off('change.tl_change', handleObj.selector)

    // on focus lets set the previous value of the element to a data attr
    function focusHandler(e) {
        var $el = $(this);
        $'tl-previous-val', $el.val());

// usage
$('.some-element').on('tl_change', '.delegate-maybe', function (e, prev, current) {
    console.log(e);         // regular event object
    console.log(prev);      // previous value of input (before change)
    console.log(current);   // current value of input (after change)
    console.log(this);      // element

Getting Current time to display in Label.


total.Text = DateTime.Now.ToString()


Dim theDate As DateTime = System.DateTime.Now
total.Text = theDate.ToString()

You declare Start as an Integer, while you are trying to put a DateTime in it, which is not possible.

Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

I have spent lots of time doing this I want to put my django app on my server and when I run python migrate I met this questions

And!! I set this ln -s /var/run/mysqld/mysqld.sock /tmp/mysql.sock It worked finally!

How to change the docker image installation directory?

Following advice from comments I utilize Docker systemd documentation to improve this answer. Below procedure doesn't require reboot and is much cleaner.

First create directory and file for custom configuration:

sudo mkdir -p /etc/systemd/system/docker.service.d
sudo $EDITOR /etc/systemd/system/docker.service.d/docker-storage.conf

For docker version before 17.06-ce paste:

ExecStart=/usr/bin/docker daemon -H fd:// --graph="/mnt"

For docker after 17.06-ce paste:

ExecStart=/usr/bin/dockerd -H fd:// --data-root="/mnt"

Alternative method through daemon.json

I recently tried above procedure with 17.09-ce on Fedora 25 and it seem to not work. Instead of that simple modification in /etc/docker/daemon.json do the trick:

    "graph": "/mnt",
    "storage-driver": "overlay"

Despite the method you have to reload configuration and restart Docker:

sudo systemctl daemon-reload
sudo systemctl restart docker

To confirm that Docker was reconfigured:

docker info|grep "loop file"

In recent version (17.03) different command is required:

docker info|grep "Docker Root Dir"

Output should look like this:

 Data loop file: /mnt/devicemapper/devicemapper/data
 Metadata loop file: /mnt/devicemapper/devicemapper/metadata


 Docker Root Dir: /mnt

Then you can safely remove old Docker storage:

rm -rf /var/lib/docker

Illegal mix of collations error in MySql

If you want to avoid changing syntax to solve this problem, try this:

Update your MySQL to version 5.5 or greater.

This resolved the problem for me.

possible EventEmitter memory leak detected

You need to clear all listeners before creating new ones using:

Client / Server


Assuming socket is your client socket / or created server socket.

You can also subscribe from specific event listeners like for example removing the connect listener like this:


SQL Server Group By Month

Restrict the dimension of the NVARCHAR to 7, supplied to CONVERT to show only "YYYY-MM"

SELECT CONVERT(NVARCHAR(7),PaymentDate,120) [Month], SUM(Amount) [TotalAmount]
FROM Payments
ORDER BY [Month]

Uncaught TypeError: Object #<Object> has no method 'movingBoxes'

I found that I was using a selector for my rendorTo div that I was using to render my column highcharts graph. Apparently it adds the selector for you so you just need to pass id.

renderTo: $('#myGraphDiv') to a string 'myGraphDiv' this fixed the error hope this helps someone else out as well.

update to python 3.7 using anaconda

This can be installed via conda with the command conda install -c anaconda python=3.7 as per

Though not all packages support 3.7 yet, running conda update --all may resolve some dependency failures.

Default value of 'boolean' and 'Boolean' in Java

class BooleanTester
    boolean primitive;
    Boolean object;

    public static void main(String[] args) {
        BooleanTester booleanTester = new BooleanTester();
        System.out.println("primitive: " + booleanTester.getPrimitive());
        System.out.println("object: " + booleanTester.getObject());

    public boolean getPrimitive() {
        return primitive;

    public Boolean getObject() {
        return object;


primitive: false
object: null

This seems obvious but I had a situation where Jackson, while serializing an object to JSON, was throwing an NPE after calling a getter, just like this one, that returns a primitive boolean which was not assigned. This led me to believe that Jackson was receiving a null and trying to call a method on it, hence the NPE. I was wrong.

Moral of the story is that when Java allocates memory for a primitive, that memory has a value even if not initialized, which Java equates to false for a boolean. By contrast, when allocating memory for an uninitialized complex object like a Boolean, it allocates only space for a reference to that object, not the object itself - there is no object in memory to refer to - so resolving that reference results in null.

I think that strictly speaking, "defaults to false" is a little off the mark. I think Java does not allocate the memory and assign it a value of false until it is explicitly set; I think Java allocates the memory and whatever value that memory happens to have is the same as the value of 'false'. But for practical purpose they are the same thing.

Http Basic Authentication in Java using HttpClient?

Here are a few points:

  • You could consider upgrading to HttpClient 4 (generally speaking, if you can, I don't think version 3 is still actively supported).

  • A 500 status code is a server error, so it might be useful to see what the server says (any clue in the response body you're printing?). Although it might be caused by your client, the server shouldn't fail this way (a 4xx error code would be more appropriate if the request is incorrect).

  • I think setDoAuthentication(true) is the default (not sure). What could be useful to try is pre-emptive authentication works better:


Otherwise, the main difference between curl -d "" and what you're doing in Java is that, in addition to Content-Length: 0, curl also sends Content-Type: application/x-www-form-urlencoded. Note that in terms of design, you should probably send an entity with your POST request anyway.

Passing arguments forward to another javascript function

try this

function global_func(...args){
  for(let i of args){

global_func('task_name', 'action', [{x: 'x'},{x: 'x'}], {x: 'x'}, ['x1','x2'], 1, null, undefined, false, true)

//(2) [{...},
//    {...}]
//    {
//        x:"x"
//    }
//(2) [
//        "x1",
//        "x2"
//    ]
//func how to deserialize without using the default constructor?

A bit late and not exactly suited here, but I'm gonna add my solution here, because my question had been closed as a duplicate of this one, and because this solution is completely different.

I needed a general way to instruct Json.NET to prefer the most specific constructor for a user defined struct type, so I can omit the JsonConstructor attributes which would add a dependency to the project where each such struct is defined.

I've reverse engineered a bit and implemented a custom contract resolver where I've overridden the CreateObjectContract method to add my custom creation logic.

public class CustomContractResolver : DefaultContractResolver {

    protected override JsonObjectContract CreateObjectContract(Type objectType)
        var c = base.CreateObjectContract(objectType);
        if (!IsCustomStruct(objectType)) return c;

        IList<ConstructorInfo> list = objectType.GetConstructors(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).OrderBy(e => e.GetParameters().Length).ToList();
        var mostSpecific = list.LastOrDefault();
        if (mostSpecific != null)
            c.OverrideCreator = CreateParameterizedConstructor(mostSpecific);
            c.CreatorParameters.AddRange(CreateConstructorParameters(mostSpecific, c.Properties));

        return c;

    protected virtual bool IsCustomStruct(Type objectType)
        return objectType.IsValueType && !objectType.IsPrimitive && !objectType.IsEnum && !objectType.Namespace.IsNullOrEmpty() && !objectType.Namespace.StartsWith("System.");

    private ObjectConstructor<object> CreateParameterizedConstructor(MethodBase method)
        var c = method as ConstructorInfo;
        if (c != null)
            return a => c.Invoke(a);
        return a => method.Invoke(null, a);

I'm using it like this.

public struct Test {
  public readonly int A;
  public readonly string B;

  public Test(int a, string b) {
    A = a;
    B = b;

var json = JsonConvert.SerializeObject(new Test(1, "Test"), new JsonSerializerSettings {
  ContractResolver = new CustomContractResolver()
var t = JsonConvert.DeserializeObject<Test>(json);

Is JavaScript's "new" keyword considered harmful?

The rationale behind not using the new keyword, is simple:

By not using it at all, you avoid the pitfall that comes with accidentally omitting it. The construction pattern that YUI uses, is an example of how you can avoid the new keyword altogether"

var foo = function () {
    var pub= { };
    return pub;
var bar = foo();

Alternatively you could so this:

function foo() { }
var bar = new foo();

But by doing so you run risk of someone forgetting to use the new keyword, and the this operator being all fubar. AFAIK there is no advantage to doing this (other than you are used to it).

At The End Of The Day: It's about being defensive. Can you use the new statement? Yes. Does it make your code more dangerous? Yes.

If you have ever written C++, it's akin to setting pointers to NULL after you delete them.

Initialize a vector array of strings

same as @Moo-Juice:

const char* args[] = {"01", "02", "03", "04"};
std::vector<std::string> v(args, args + sizeof(args)/sizeof(args[0])); //get array size

How to update a record using sequelize for node?

If you're here looking for a way to increment a specific field value in a model...

This worked for me as of [email protected]

User.increment("field", {by: 1, where: {id: 1});


Multiprocessing: How to use on a function defined in a class?

I know this was asked over 6 years ago now, but just wanted to add my solution, as some of the suggestions above seem horribly complicated, but my solution was actually very simple.

All I had to do was wrap the call to a helper function. Passing the class object along with args for the method as a tuple, which looked a bit like this.

def run_in_parallel(args):
    return args[0].method(args[1])

myclass = MyClass()
method_args = [1,2,3,4,5,6]
args_map = [ (myclass, arg) for arg in method_args ]
pool = Pool(), args_map)

Default property value in React component using TypeScript

For the functional component, I would rather keep the props argument, so here is my solution:

interface Props {
  foo: string;
  bar?: number; 

// IMPORTANT!, defaultProps is of type {bar: number} rather than Partial<Props>!
const defaultProps = {
  bar: 1

// externalProps is of type Props
const FooComponent = exposedProps => {
  // props works like type Required<Props> now!
  const props = Object.assign(defaultProps, exposedProps);

  return ...

FooComponent.defaultProps = defaultProps;

React setState not updating state

The setState() operation is asynchronous and hence your console.log() will be executed before the setState() mutates the values and hence you see the result.

To solve it, log the value in the callback function of setState(), like:

setTimeout(() => {
    this.setState({dealersOverallTotal: total},
       console.log(this.state.dealersOverallTotal, 'dealersOverallTotal1');
}, 10)

Seeing the console's output in Visual Studio 2010?

System.Diagnostics.Debug.WriteLine() will work, but you have to be looking in the right place for the output. In Visual Studio 2010, on the menu bar, click Debug -> Windows -> Output. Now, at the bottom of the screen docked next to your error list, there should be an output tab. Click it and double check it's showing output from the debug stream on the dropdown list.

P.S.: I think the output window shows on a fresh install, but I can't remember. If it doesn't, or if you closed it by accident, follow these instructions.

Manually map column names with class properties

for all of you who use Dapper 1.12, Here's what you need to do to get this done:

  • Add a new column attribute class:

      [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property]
      public class ColumnAttribute : Attribute
        public string Name { get; set; }
        public ColumnAttribute(string name)
          this.Name = name;

  • Search for this line:

    map = new DefaultTypeMap(type);

    and comment it out.

  • Write this instead:

            map = new CustomPropertyTypeMap(type, (t, columnName) =>
              PropertyInfo pi = t.GetProperties().FirstOrDefault(prop =>
                                    .Any(attr => attr.Name == columnName));
              return pi != null ? pi : t.GetProperties().FirstOrDefault(prop => prop.Name == columnName);

  • What does %s mean in a python format string?

    Here is a good example in Python3.

      >>> a = input("What is your name?")
      What is your name?Peter
      >>> b = input("Where are you from?")
      Where are you from?DE
      >>> print("So you are %s of %s" % (a, b))
      So you are Peter of DE

    Nodejs send file in response

    Here's an example program that will send myfile.mp3 by streaming it from disk (that is, it doesn't read the whole file into memory before sending the file). The server listens on port 2000.

    [Update] As mentioned by @Aftershock in the comments, util.pump is gone and was replaced with a method on the Stream prototype called pipe; the code below reflects this.

    var http = require('http'),
        fileSystem = require('fs'),
        path = require('path');
    http.createServer(function(request, response) {
        var filePath = path.join(__dirname, 'myfile.mp3');
        var stat = fileSystem.statSync(filePath);
        response.writeHead(200, {
            'Content-Type': 'audio/mpeg',
            'Content-Length': stat.size
        var readStream = fileSystem.createReadStream(filePath);
        // We replaced all the event handlers with a simple call to readStream.pipe()

    Taken from

    Conversion from 12 hours time to 24 hours time in java

    I was looking for same thing but in number, means from integer xx hour, xx minutes and AM/PM to 24 hour format xx hour and xx minutes, so here what i have done:

    private static final int AM = 0;
    private static final int PM = 1;
       * Based on concept: day start from 00:00AM and ends at 11:59PM, 
       * afternoon 12 is 12PM, 12:xxAM is basically 00:xxAM
       * @param hour12Format
       * @param amPm
       * @return
      private int get24FormatHour(int hour12Format,int amPm){
        if(hour12Format==12 && amPm==AM){
        if(amPm == PM && hour12Format!=12){
        return hour12Format;
        private int minutesTillMidnight(int hour12Format,int minutes, int amPm){
            int hour24Format=get24FormatHour(hour12Format,amPm);
            System.out.println("24 Format :"+hour24Format+":"+minutes); 
            return (hour24Format*60)+minutes;

    How to make the first option of <select> selected with jQuery

    If you have disabled options, you may add not([disabled]) to prevent selecting them which results into the following:

    $("#target option:not([disabled]):first").attr('selected','selected')

    How does the "final" keyword in Java work? (I can still modify an object.)

    You are always allowed to initialize a final variable. The compiler makes sure that you can do it only once.

    Note that calling methods on an object stored in a final variable has nothing to do with the semantics of final. In other words: final is only about the reference itself, and not about the contents of the referenced object.

    Java has no concept of object immutability; this is achieved by carefully designing the object, and is a far-from-trivial endeavor.

    MIT vs GPL license

    IANAL but as I see it....

    While you can combine GPL and MIT code, the GPL is tainting. Which means the package as a whole gets the limitations of the GPL. As that is more restrictive you can no longer use it in commercial (or rather closed source) software. Which also means if you have a MIT/BSD/ASL project you will not want to add dependencies to GPL code.

    Adding a GPL dependency does not change the license of your code but it will limit what people can do with the artifact of your project. This is also why the ASF does not allow dependencies to GPL code for their projects.

    Select distinct values from a list using LINQ in C#


    var newList = 
    from x in empCollection
    select new {Loc = x.empLoc, PL = x.empPL, Shift = x.empShift}

    How to automatically add user account AND password with a Bash script?

    I was asking myself the same thing, and didn't want to rely on a Python script.

    This is the line to add a user with a defined password in one bash line:

    useradd -p $(openssl passwd -crypt $PASS) $USER

    How can I get a resource content from a static context?

    Getting image resouse as InputStream without context:

    Class<? extends MyClass> aClass = MyClass.class;
    URL r = aClass.getResource("/res/raw/test.png");
    URLConnection urlConnection = r.openConnection();
    return new BufferedInputStream(urlConnection.getInputStream());

    If you need derectory tree for your files, it will also works (assets supports sub-dirs):

    URL r = aClass.getResource("/assets/images/base/2.png");

    What's with the dollar sign ($"string")

    It's the new feature in C# 6 called Interpolated Strings.

    The easiest way to understand it is: an interpolated string expression creates a string by replacing the contained expressions with the ToString representations of the expressions' results.

    For more details about this, please take a look at MSDN.

    Now, think a little bit more about it. Why this feature is great?

    For example, you have class Point:

    public class Point
        public int X { get; set; }
        public int Y { get; set; }

    Create 2 instances:

    var p1 = new Point { X = 5, Y = 10 };
    var p2 = new Point { X = 7, Y = 3 };

    Now, you want to output it to the screen. The 2 ways that you usually use:

    Console.WriteLine("The area of interest is bounded by (" + p1.X + "," + p1.Y + ") and (" + p2.X + "," + p2.Y + ")");

    As you can see, concatenating string like this makes the code hard to read and error-prone. You may use string.Format() to make it nicer:

    Console.WriteLine(string.Format("The area of interest is bounded by({0},{1}) and ({2},{3})", p1.X, p1.Y, p2.X, p2.Y));

    This creates a new problem:

    1. You have to maintain the number of arguments and index yourself. If the number of arguments and index are not the same, it will generate a runtime error.

    For those reasons, we should use new feature:

    Console.WriteLine($"The area of interest is bounded by ({p1.X},{p1.Y}) and ({p2.X},{p2.Y})");

    The compiler now maintains the placeholders for you so you don’t have to worry about indexing the right argument because you simply place it right there in the string.

    For the full post, please read this blog.

    Calculate business days

    // $today is the UNIX timestamp for today's date
    $today = time();
    echo "<strong>Today is (ORDER DATE): " . '<font color="red">' . date('l, F j, Y', $today) . "</font></strong><br/><br/>";
    //The numerical representation for day of week (Ex. 01 for Monday .... 07 for Sunday
    $today_numerical = date("N",$today);
    //leadtime_days holds the numeric value for the number of business days 
    $leadtime_days = $_POST["leadtime"];
    //leadtime is the adjusted date for shipdate
    $shipdate = time();
    while ($leadtime_days > 0) 
     if ($today_numerical != 5 && $today_numerical != 6)
      $shipdate = $shipdate + (60*60*24);
      $today_numerical = date("N",$shipdate);
      $leadtime_days --;
      $shipdate = $shipdate + (60*60*24);
      $today_numerical = date("N",$shipdate);
    echo '<strong>Estimated Ship date: ' . '<font color="green">' . date('l, F j, Y', $shipdate) . "</font></strong>";

    String replace method is not replacing characters

    You should re-assign the result of the replacement, like this:

     sentence = sentence.replace("and", " ");

    Be aware that the String class is immutable, meaning that all of its methods return a new string and never modify the original string in-place, so the result of invoking a method in an instance of String must be assigned to a variable or used immediately for the change to take effect.

    Need to remove href values when printing in Chrome

    It doesn't. Somewhere in your print stylesheet, you must have this section of code:

    a[href]::after {
        content: " (" attr(href) ")"

    The only other possibility is you have an extension doing it for you.

    Laravel Check If Related Model Exists

    After Php 7.1, The accepted answer won't work for all types of relationships.

    Because depending of type the relationship, Eloquent will return a Collection, a Model or Null. And in Php 7.1 count(null) will throw an error.

    So, to check if the relation exist you can use:

    For relationships single: For example hasOne and belongsTo

    if(!is_null($model->relation)) {

    For relationships multiple: For Example: hasMany and belongsToMany

    if ($model->relation->isNotEmpty()) {

    Detect home button press in android

    I had this problem, and since overriding the onKeyDown() method didn't accomplish anything because of the underlying android system didn't call this method, I solved this with overriding onBackPressed(), and I had a boolean value set there to false, because I pressed back, let me show you what I mean in code:

    import android.util.Log;
    public class HomeButtonActivity extends Activity {
        boolean homePressed = false;
        // override onCreate() here.
        public void onBackPressed() {
            homePressed = false; // simply set homePressed to false
        public void onResume() {
            homePressed = true; // default: other wise onBackPressed will set it to false
        public void onPause() {
            if(homePressed) { Log.i("homePressed", "yay"); }

    So the reason why this worked is because the only way to navigate outside this activity is by pressing back or home so if back was pressed then i know the cause wasn't home, but otherwise the cause was home, therefore i set the default boolean value for homePressed to be true. However this will only work with a single activity instance in your application because otherwise you have more possibilities to cause the onPause() method to be called.

    How to replace NaN values by Zeroes in a column of a Pandas Dataframe?

    There are two options available primarily; in case of imputation or filling of missing values NaN / np.nan with only numerical replacements (across column(s):

    df['Amount'].fillna(value=None, method= ,axis=1,) is sufficient:

    From the Documentation:

    value : scalar, dict, Series, or DataFrame Value to use to fill holes (e.g. 0), alternately a dict/Series/DataFrame of values specifying which value to use for each index (for a Series) or column (for a DataFrame). (values not in the dict/Series/DataFrame will not be filled). This value cannot be a list.

    Which means 'strings' or 'constants' are no longer permissable to be imputed.

    For more specialized imputations use SimpleImputer():

    from sklearn.impute import SimpleImputer
    si = SimpleImputer(strategy='constant', missing_values=np.nan, fill_value='Replacement_Value')
    df[['Col-1', 'Col-2']] = si.fit_transform(X=df[['C-1', 'C-2']])

    Bootstrap 3.0 - Fluid Grid that includes Fixed Column Sizes

    UPDATE 2014-11-14: The solution below is too old, I recommend using flex box layout method. Here is a overview:

    My solution


    <li class="grid-list-header row-cw row-cw-msg-list ...">
      <div class="col-md-1 col-cw col-cw-name">
      <div class="col-md-1 col-cw col-cw-keyword">
      <div class="col-md-1 col-cw col-cw-reply">
      <div class="col-md-1 col-cw col-cw-action">
    <li class="grid-list-item row-cw row-cw-msg-list ...">
      <div class="col-md-1 col-cw col-cw-name">
      <div class="col-md-1 col-cw col-cw-keyword">
      <div class="col-md-1 col-cw col-cw-reply">
      <div class="col-md-1 col-cw col-cw-action">


    .row-cw {
      position: relative;
    .col-cw {
      position: absolute;
      top: 0;
    .ir-msg-list {
      $col-reply-width: 140px;
      $col-action-width: 130px;
      .row-cw-msg-list {
        padding-right: $col-reply-width + $col-action-width;
      .col-cw-name {
        width: 50%;
      .col-cw-keyword {
        width: 50%;
      .col-cw-reply {
        width: $col-reply-width;
        right: $col-action-width;
      .col-cw-action {
        width: $col-action-width;
        right: 0;

    Without modify too much bootstrap layout code.

    Update (not from OP): adding code snippet below to facilitate understanding of this answer. But it doesn't seem to work as expected.

    ul {_x000D_
      list-style: none;_x000D_
    .row-cw {_x000D_
      position: relative;_x000D_
      height: 20px;_x000D_
    .col-cw {_x000D_
      position: absolute;_x000D_
      top: 0;_x000D_
      background-color: rgba(150, 150, 150, .5);_x000D_
    .row-cw-msg-list {_x000D_
      padding-right: 270px;_x000D_
    .col-cw-name {_x000D_
      width: 50%;_x000D_
      background-color: rgba(150, 0, 0, .5);_x000D_
    .col-cw-keyword {_x000D_
      width: 50%;_x000D_
      background-color: rgba(0, 150, 0, .5);_x000D_
    .col-cw-reply {_x000D_
      width: 140px;_x000D_
      right: 130px;_x000D_
      background-color: rgba(0, 0, 150, .5);_x000D_
    .col-cw-action {_x000D_
      width: 130px;_x000D_
      right: 0;_x000D_
      background-color: rgba(150, 150, 0, .5);_x000D_
    <ul class="ir-msg-list">_x000D_
      <li class="grid-list-header row-cw row-cw-msg-list">_x000D_
        <div class="col-md-1 col-cw col-cw-name">name</div>_x000D_
        <div class="col-md-1 col-cw col-cw-keyword">keyword</div>_x000D_
        <div class="col-md-1 col-cw col-cw-reply">reply</div>_x000D_
        <div class="col-md-1 col-cw col-cw-action">action</div>_x000D_
      <li class="grid-list-item row-cw row-cw-msg-list">_x000D_
        <div class="col-md-1 col-cw col-cw-name">name</div>_x000D_
        <div class="col-md-1 col-cw col-cw-keyword">keyword</div>_x000D_
        <div class="col-md-1 col-cw col-cw-reply">reply</div>_x000D_
        <div class="col-md-1 col-cw col-cw-action">action</div>_x000D_

    how to show only even or odd rows in sql server 2008?

    SELECT *
         SELECT rownum rn, empno, ename
         FROM emp
      ) temp
      WHERE  MOD(temp.rn,2) = 1

    How to scroll to an element?

    The nicest way is to use element.scrollIntoView({ behavior: 'smooth' }). This scrolls the element into view with a nice animation.

    When you combine it with React's useRef(), it can be done the following way.

    import React, { useRef } from 'react'
    const Article = () => {
      const titleRef = useRef()
      function handleBackClick() {
          titleRef.current.scrollIntoView({ behavior: 'smooth' })
      return (
                <h1 ref={titleRef}>
                    A React article for Latin readers
                // Rest of the article's content...
                <button onClick={handleBackClick}>
                    Back to the top

    When you would like to scroll to a React component, you need to forward the ref to the rendered element. This article will dive deeper into the problem.

    JFrame Maximize window

    The way to set JFrame to full-screen, is to set MAXIMIZED_BOTH option which stands for MAXIMIZED_VERT | MAXIMIZED_HORIZ, which respectively set the frame to maximize vertically and horizontally

    package Example;
    import java.awt.GraphicsConfiguration;
    import javax.swing.JFrame;
    import javax.swing.JButton;
    public class JFrameExample
        static JFrame frame;
        static GraphicsConfiguration gc;
        public static void main(String[] args)
            frame = new JFrame(gc);
            frame.setTitle("Full Screen Example");
            JButton button = new JButton("exit");
            b.addActionListener(new ActionListener(){@Override
            public void actionPerformed(ActionEvent arg0){

    Difference between res.send and res.json in Express.js

    The methods are identical when an object or array is passed, but res.json() will also convert non-objects, such as null and undefined, which are not valid JSON.

    The method also uses the json replacer and json spaces application settings, so you can format JSON with more options. Those options are set like so:

    app.set('json spaces', 2);
    app.set('json replacer', replacer);

    And passed to a JSON.stringify() like so:

    JSON.stringify(value, replacer, spacing);
    // value: object to format
    // replacer: rules for transforming properties encountered during stringifying
    // spacing: the number of spaces for indentation

    This is the code in the res.json() method that the send method doesn't have:

    var app =;
    var replacer = app.get('json replacer');
    var spaces = app.get('json spaces');
    var body = JSON.stringify(obj, replacer, spaces);

    The method ends up as a res.send() in the end:

    this.charset = this.charset || 'utf-8';
    this.get('Content-Type') || this.set('Content-Type', 'application/json');
    return this.send(body);

    How to file split at a line number

    # set first K lines:
    # line count (N): 
    N=$(wc -l < $file_name)
    # length of the bottom file:
    L=$(( $N - $K ))
    # create the top of file: 
    head -n $K $file_name > top_$file_name
    # create bottom of file: 
    tail -n $L $file_name > bottom_$file_name

    Also, on second thought, split will work in your case, since the first split is larger than the second. Split puts the balance of the input into the last split, so

    split -l 300000 file_name

    will output xaa with 300k lines and xab with 100k lines, for an input with 400k lines.

    How to change the default encoding to UTF-8 for Apache?

    In my case add to .htaccess

    AddDefaultCharset off
    AddDefaultCharset windows-1252

    Stick button to right side of div

    Normally I would recommend floating but from your 3 requirements I would suggest this:

    position: absolute;
    right: 10px;
    top: 5px;

    Don't forget position: relative; on the parent div


    How to check if a value exists in an array in Ruby

    If you want to check by a block, you could try any? or all?.

    %w{ant bear cat}.any? {|word| word.length >= 3}   #=> true  
    %w{ant bear cat}.any? {|word| word.length >= 4}   #=> true  
    [ nil, true, 99 ].any?                            #=> true  

    See Enumerable for more information.

    My inspiration came from "evaluate if array has any items in ruby"

    Possible to restore a backup of SQL Server 2014 on SQL Server 2012?

    You CANNOT do this - you cannot attach/detach or backup/restore a database from a newer version of SQL Server down to an older version - the internal file structures are just too different to support backwards compatibility. This is still true in SQL Server 2014 - you cannot restore a 2014 backup on anything other than another 2014 box (or something newer).

    You can either get around this problem by

    • using the same version of SQL Server on all your machines - then you can easily backup/restore databases between instances

    • otherwise you can create the database scripts for both structure (tables, view, stored procedures etc.) and for contents (the actual data contained in the tables) either in SQL Server Management Studio (Tasks > Generate Scripts) or using a third-party tool

    • or you can use a third-party tool like Red-Gate's SQL Compare and SQL Data Compare to do "diffing" between your source and target, generate update scripts from those differences, and then execute those scripts on the target platform; this works across different SQL Server versions.

    The compatibility mode setting just controls what T-SQL features are available to you - which can help to prevent accidentally using new features not available in other servers. But it does NOT change the internal file format for the .mdf files - this is NOT a solution for that particular problem - there is no solution for restoring a backup from a newer version of SQL Server on an older instance.

    Apply global variable to Vuejs

    You can use a Global Mixin to affect every Vue instance. You can add data to this mixin, making a value/values available to all vue components.

    To make that value Read Only, you can use the method described in this Stack Overflow answer.

    Here is an example:

    // This is a global mixin, it is applied to every vue instance. 
    // Mixins must be instantiated *before* your call to new Vue(...)
      data: function() {
        return {
          get globalReadOnlyProperty() {
            return "Can't change me!";
    Vue.component('child', {
      template: "<div>In Child: {{globalReadOnlyProperty}}</div>"
    new Vue({
      el: '#app',
      created: function() {
        this.globalReadOnlyProperty = "This won't change it";
    <script src=""></script>
    <div id="app">
      In Root: {{globalReadOnlyProperty}}

    Get multiple elements by Id

    If you're not religious about keeping your HTML valid then I can see use cases where having the same ID on multiple elements may be useful.

    One example is testing. Often we identify elements to test against by finding all elements with a particular class. However, if we find ourselves adding classes purely for testing purposes, then I would contend that that's wrong. Classes are for styling, not identification.

    If IDs are for identification, why must it be that only one element can have a particular identifier? Particularly in today's frontend world, with reusable components, if we don't want to use classes for identification, then we need to use IDs. But, if we use multiples of a component, we'll have multiple elements with the same ID.

    I'm saying that's OK. If that's anathema to you, that's fine, I understand your view. Let's agree to disagree and move on.

    If you want a solution that actually finds all IDs of the same name though, then it's this:

    function getElementsById(id) {
        const elementsWithId = []
        const allElements = document.getElementsByTagName('*')
        for(let key in allElements) {
            if(allElements.hasOwnProperty(key)) {
                const element = allElements[key]
                if( === id) {
        return elementsWithId

    EDIT, ES6 FTW:

    function getElementsById(id) {
        return [...document.getElementsByTagName('*')].filter(element => === id)

    How to beautify JSON in Python?

    Your data is poorly formed. The value fields in particular have numerous spaces and new lines. Automated formatters won't work on this, as they will not modify the actual data. As you generate the data for output, filter it as needed to avoid the spaces.

    How to check whether a string contains a substring in Ruby

    You can use the include? method:

    my_string = "abcdefg"
    if my_string.include? "cde"
       puts "String includes 'cde'"

    Resetting Select2 value in dropdown with reset button

    you can used:


    It's very simple and work right! If use with reset button:

    $('#btnReset').click(function() {

    PHP namespaces and "use"

    The use operator is for giving aliases to names of classes, interfaces or other namespaces. Most use statements refer to a namespace or class that you'd like to shorten:

    use My\Full\Namespace;

    is equivalent to:

    use My\Full\Namespace as Namespace;
    // Namespace\Foo is now shorthand for My\Full\Namespace\Foo

    If the use operator is used with a class or interface name, it has the following uses:

    // after this, "new DifferentName();" would instantiate a My\Full\Classname
    use My\Full\Classname as DifferentName;
    // global class - making "new ArrayObject()" and "new \ArrayObject()" equivalent
    use ArrayObject;

    The use operator is not to be confused with autoloading. A class is autoloaded (negating the need for include) by registering an autoloader (e.g. with spl_autoload_register). You might want to read PSR-4 to see a suitable autoloader implementation.

    PHP Unset Session Variable

    // set
    $_SESSION['test'] = 1;
    // destroy

    What are the uses of the exec command in shell scripts?

    The exec built-in command mirrors functions in the kernel, there are a family of them based on execve, which is usually called from C.

    exec replaces the current program in the current process, without forking a new process. It is not something you would use in every script you write, but it comes in handy on occasion. Here are some scenarios I have used it;

    1. We want the user to run a specific application program without access to the shell. We could change the sign-in program in /etc/passwd, but maybe we want environment setting to be used from start-up files. So, in (say) .profile, the last statement says something like:

       exec appln-program

      so now there is no shell to go back to. Even if appln-program crashes, the end-user cannot get to a shell, because it is not there - the exec replaced it.

    2. We want to use a different shell to the one in /etc/passwd. Stupid as it may seem, some sites do not allow users to alter their sign-in shell. One site I know had everyone start with csh, and everyone just put into their .login (csh start-up file) a call to ksh. While that worked, it left a stray csh process running, and the logout was two stage which could get confusing. So we changed it to exec ksh which just replaced the c-shell program with the korn shell, and made everything simpler (there are other issues with this, such as the fact that the ksh is not a login-shell).

    3. Just to save processes. If we call prog1 -> prog2 -> prog3 -> prog4 etc. and never go back, then make each call an exec. It saves resources (not much, admittedly, unless repeated) and makes shutdown simplier.

    You have obviously seen exec used somewhere, perhaps if you showed the code that's bugging you we could justify its use.

    Edit: I realised that my answer above is incomplete. There are two uses of exec in shells like ksh and bash - used for opening file descriptors. Here are some examples:

    exec 3< thisfile          # open "thisfile" for reading on file descriptor 3
    exec 4> thatfile          # open "thatfile" for writing on file descriptor 4
    exec 8<> tother           # open "tother" for reading and writing on fd 8
    exec 6>> other            # open "other" for appending on file descriptor 6
    exec 5<&0                 # copy read file descriptor 0 onto file descriptor 5
    exec 7>&4                 # copy write file descriptor 4 onto 7
    exec 3<&-                 # close the read file descriptor 3
    exec 6>&-                 # close the write file descriptor 6

    Note that spacing is very important here. If you place a space between the fd number and the redirection symbol then exec reverts to the original meaning:

      exec 3 < thisfile       # oops, overwrite the current program with command "3"

    There are several ways you can use these, on ksh use read -u or print -u, on bash, for example:

    read <&3
    echo stuff >&4

    You are trying to add a non-nullable field 'new_field' to userprofile without a default

    You need to provide a default value:

    new_field = models.CharField(max_length=140, default='SOME STRING')

    Configure Nginx with proxy_pass

    Nginx prefers prefix-based location matches (not involving regular expression), that's why in your code block, /stash redirects are going to /.

    The algorithm used by Nginx to select which location to use is described thoroughly here:

    Inline CSS styles in React: how to implement a:hover?

    I think onMouseEnter and onMouseLeave are the ways to go, but I don't see the need for an additional wrapper component. Here is how I implemented it:

    var Link = React.createClass({
      getInitialState: function(){
        return {hover: false}
      toggleHover: function(){
        this.setState({hover: !this.state.hover})
      render: function() {
        var linkStyle;
        if (this.state.hover) {
          linkStyle = {backgroundColor: 'red'}
        } else {
          linkStyle = {backgroundColor: 'blue'}
            <a style={linkStyle} onMouseEnter={this.toggleHover} onMouseLeave={this.toggleHover}>Link</a>

    You can then use the state of hover (true/false) to change the style of the link.

    HashMap: One Key, multiple Values

    Libraries exist to do this, but the simplest plain Java way is to create a Map of List like this:

    Map<Object,ArrayList<Object>> multiMap = new HashMap<>();

    sum two columns in R

    Try this for creating a column3 as a sum of column1 + column 2 in a table


    Bash scripting missing ']'

    You're missing a space after "p1":

    if [ -s "p1" ];

    Can't connect to Postgresql on port 5432

    You probably need to either open up the port to access it in your LAN (or outside of it) or bind the network address to the port (make PostgreSQL listen on your LAN instead of just on localhost)