Programs & Examples On #Geneva server

AD FS 2.0 is the offical name for Geneva server

MySQL - DATE_ADD month interval

DATE_ADD works correctly. 1 January plus 6 months is 1 July, just like 1 January plus 1 month is 1 of February.

Between operation is inclusive. So, you are getting everything up to, and including, 1 July. (see also MySQL "between" clause not inclusive?)

What you need to do is subtract 1 day or use < operator instead of between.

Can I escape a double quote in a verbatim string literal?

This should help clear up any questions you may have: C# literals

Here is a table from the linked content:

Regular literal Verbatim literal Resulting string
"Hello" @"Hello" Hello
"Backslash: \\" @"Backslash: \" Backslash: \
"Quote: \"" @"Quote: """ Quote: "
"CRLF:\r\nPost CRLF" @"CRLF:
Post CRLF"

Should I use JSLint or JSHint JavaScript validation?

I had the same question a couple of weeks ago and was evaluating both JSLint and JSHint.

Contrary to the answers in this question, my conclusion was not:

By all means use JSLint.


If you're looking for a very high standard for yourself or team, JSLint.

As you can configure almost the same rules in JSHint as in JSLint. So I would argue that there's not much difference in the rules you could achieve.

So the reasons to choose one over another are more political than technical.

We've finally decided to go with JSHint because of the following reasons:

  • Seems to be more configurable that JSLint.
  • Looks definitely more community-driven rather than one-man-show (no matter how cool The Man is).
  • JSHint matched our code style OOTB better that JSLint.

How to copy a map?

You have to manually copy each key/value pair to a new map. This is a loop that people have to reprogram any time they want a deep copy of a map.

You can automatically generate the function for this by installing mapper from the maps package using

go get -u

and running

mapper -types string:aStruct

which will generate the file map_float_astruct.go containing not only a (deep) Copy for your map but also other "missing" map functions ContainsKey, ContainsValue, GetKeys, and GetValues:

func ContainsKeyStringAStruct(m map[string]aStruct, k string) bool {
    _, ok := m[k]
    return ok

func ContainsValueStringAStruct(m map[string]aStruct, v aStruct) bool {
    for _, mValue := range m {
        if mValue == v {
            return true

    return false

func GetKeysStringAStruct(m map[string]aStruct) []string {
    keys := []string{}

    for k, _ := range m {
        keys = append(keys, k)

    return keys

func GetValuesStringAStruct(m map[string]aStruct) []aStruct {
    values := []aStruct{}

    for _, v := range m {
        values = append(values, v)

    return values

func CopyStringAStruct(m map[string]aStruct) map[string]aStruct {
    copyMap := map[string]aStruct{}

    for k, v := range m {
        copyMap[k] = v

    return copyMap

Full disclosure: I am the creator of this tool. I created it and its containing package because I found myself constantly rewriting these algorithms for the Go map for different type combinations.

SQL Server: Attach incorrect version 661

To clarify, a database created under SQL Server 2008 R2 was being opened in an instance of SQL Server 2008 (the version prior to R2). The solution for me was to simply perform an upgrade installation of SQL Server 2008 R2. I can only speak for the Express edition, but it worked.

Oddly, though, the Web Platform Installer indicated that I had Express R2 installed. The better way to tell is to ask the database server itself:


How to add more than one machine to the trusted hosts list using winrm

I created a module to make dealing with trusted hosts slightly easier, psTrustedHosts. You can find the repo here on GitHub. It provides four functions that make working with trusted hosts easy: Add-TrustedHost, Clear-TrustedHost, Get-TrustedHost, and Remove-TrustedHost. You can install the module from PowerShell Gallery with the following command:

Install-Module psTrustedHosts -Force

In your example, if you wanted to append hosts 'machineC' and 'machineD' you would simply use the following command:

Add-TrustedHost 'machineC','machineD'

To be clear, this adds hosts 'machineC' and 'machineD' to any hosts that already exist, it does not overwrite existing hosts.

The Add-TrustedHost command supports pipeline processing as well (so does the Remove-TrustedHost command) so you could also do the following:

'machineC','machineD' | Add-TrustedHost

Benefits of inline functions in C++?

Our computer science professor urged us to never use inline in a c++ program. When asked why, he kindly explained to us that modern compilers should detect when to use inline automatically.

So yes, the inline can be an optimization technique to be used wherever possible, but apparently this is something that is already done for you whenever it's possible to inline a function anyways.

Read from a gzip file in python

Try gzipping some data through the gzip libary like this...

import gzip
content = "Lots of content here"
f ='Onlyfinnaly.log.gz', 'wb')

... then run your code as posted ...

import gzip'Onlyfinnaly.log.gz','rb')
print file_content

This method worked for me as for some reason the gzip library fails to read some files.

How to remove and clear all localStorage data

Something like this should do:

function cleanLocalStorage() {
    for(key in localStorage) {
        delete localStorage[key];

Be careful about using this, though, as the user may have other data stored in localStorage and would probably be pretty ticked if you deleted that. I'd recommend either a) not storing the user's data in localStorage or b) storing the user's account stuff in a single variable, and then clearing that instead of deleting all the keys in localStorage.

Edit: As Lyn pointed out, you'll be good with localStorage.clear(). My previous points still stand, however.

Python sum() function with list parameter

Have you used the variable sum anywhere else? That would explain it.

>>> sum = 1
>>> numbers = [1, 2, 3]
>>> numsum = (sum(numbers))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable

The name sum doesn't point to the function anymore now, it points to an integer.

Solution: Don't call your variable sum, call it total or something similar.

int to string in MySQL

You could use CONCAT, and the numeric argument of it is converted to its equivalent binary string form.

select t2.* 
from t1 join t2 
on t2.url=CONCAT('',, '%/more') where > 9000

iPhone Navigation Bar Title text color

titleTextAttributes Display attributes for the bar’s title text.

@property(nonatomic, copy) NSDictionary *titleTextAttributes Discussion You can specify the font, text color, text shadow color, and text shadow offset for the title in the text attributes dictionary, using the text attribute keys described in NSString UIKit Additions Reference.

Availability Available in iOS 5.0 and later. Declared In UINavigationBar.h

How to set Oracle's Java as the default Java in Ubuntu?

I put the line:

export JAVA_HOME=/usr/lib/jvm/java-7-oracle

in my ~/.bashrc file.

/usr/lib/jvm/java7-oracle should be a symbolic link pointing to /usr/lib/jvm/java-7-oracle-[version number here].

The reason it's a symbolic link is that in case there's a new version of the JVM, you don't need to update your .bashrc file, it should automatically point to the new version.

If you want to set JAVA_HOME environment variables globally and at system level means use should set in /etc/environment file.

How can I make SMTP authenticated in C#

using System.Net;
using System.Net.Mail;

using(SmtpClient smtpClient = new SmtpClient())
    var basicCredential = new NetworkCredential("username", "password"); 
    using(MailMessage message = new MailMessage())
        MailAddress fromAddress = new MailAddress("[email protected]"); 

        smtpClient.Host = "";
        smtpClient.UseDefaultCredentials = false;
        smtpClient.Credentials = basicCredential;

        message.From = fromAddress;
        message.Subject = "your subject";
        // Set IsBodyHtml to true means you can send HTML email.
        message.IsBodyHtml = true;
        message.Body = "<h1>your message body</h1>";
        message.To.Add("[email protected]"); 

        catch(Exception ex)
            //Error, could not send the message

You may use the above code.

removing bold styling from part of a header

If you don't want a separate CSS file, you can use inline CSS:

<h1>This text should be bold, <span style="font-weight:normal">but this text should not</span></h1>

However, as Madara's comment suggests, you might want to consider putting the unbolded part in a different header, depending on the use case involved.

set the iframe height automatically

If the sites are on separate domains, the calling page can't access the height of the iframe due to cross-browser domain restrictions. If you have access to both sites, you may be able to use the [document domain hack].1 Then anroesti's links should help.

Find indices of elements equal to zero in a NumPy array

I would do it the following way:

>>> x = np.array([[1,0,0], [0,2,0], [1,1,0]])
>>> x
array([[1, 0, 0],
       [0, 2, 0],
       [1, 1, 0]])
>>> np.nonzero(x)
(array([0, 1, 2, 2]), array([0, 1, 0, 1]))

# if you want it in coordinates
>>> x[np.nonzero(x)]
array([1, 2, 1, 1])
>>> np.transpose(np.nonzero(x))
array([[0, 0],
       [1, 1],
       [2, 0],
       [2, 1])

Getting the error "Java.lang.IllegalStateException Activity has been destroyed" when using tabs with ViewPager

I had this issue and realized it was because I was calling setContentView(int id) twice in my Activity's onCreate

Remove last commit from remote git repository

Be careful that this will create an "alternate reality" for people who have already fetch/pulled/cloned from the remote repository. But in fact, it's quite simple:

git reset HEAD^ # remove commit locally
git push origin +HEAD # force-push the new HEAD commit

If you want to still have it in your local repository and only remove it from the remote, then you can use:

git push origin +HEAD^:<name of your branch, most likely 'master'>

Socket.IO - how do I get a list of connected sockets/clients?

In Socket.IO 0.7 you have a clients method on the namespaces, this returns a array of all connected sockets.

API for no namespace:

var clients = io.sockets.clients();
var clients = io.sockets.clients('room'); // all users from room `room`

For a namespace

var clients = io.of('/chat').clients();
var clients = io.of('/chat').clients('room'); // all users from room `room`

Hopes this helps someone in the future

NOTE: This Solution ONLY works with version prior to 1.0

UPDATED 2020 Mar 06

From 1.x and above, please refer to this link: getting how many people are in a chat room in

Table row and column number in jQuery

You can use the Core/index function in a given context, for example you can check the index of the TD in it's parent TR to get the column number, and you can check the TR index on the Table, to get the row number:

  var col = $(this).parent().children().index($(this));
  var row = $(this).parent().parent().children().index($(this).parent());
  alert('Row: ' + row + ', Column: ' + col);

Check a running example here.

How to Compare a long value is equal to Long value

First your code is not compiled. Line Long b = 1113;

is wrong. You have to say

Long b = 1113L;

Second when I fixed this compilation problem the code printed "not equals".

How to validate an email address in JavaScript

Here's a simple regex that would just check for the basic format of an email e.g., [email protected]:


Split string in C every white space

char arr[50];
int c=0,i,l;


What is the difference between HTTP 1.1 and HTTP 2.0?

HTTP/2 supports queries multiplexing, headers compression, priority and more intelligent packet streaming management. This results in reduced latency and accelerates content download on modern web pages.

More details here.

Remove or uninstall library previously added : cocoapods

  1. Remove pod name(which to remove) from Podfile and then
  2. Open Terminal, set project folder path
  3. Run pod install --no-integrate

Dynamic classname inside ngClass in angular 2


<button [ngClass]="type === 'mybutton' ? namespace + '-mybutton' : ''"></button>



<button [ngClass]="[type === 'mybutton' ? namespace + '-mybutton' : '']"></button>

or even

<button class="{{type === 'mybutton' ? namespace + '-mybutton' : ''}}"></button>

will work but extra benefit of using ngClass is that it does not overwrite other classes that are added by any other method( eg: [] directive or class attribute, etc.) as class does.

Angular 9 Update

The new compiler, Ivy, brings more clarity and predictability to what happens when there are different types of class-bindings on the same element. Read More about it here.

ngClass takes three types of input

  • Object: each key corresponds to a CSS class name, you can't have dynamic keys, because key 'key' "key" are all same, and [key] is not supported AFAIK.
  • Array: can only contain list of classes, no conditions, although ternary operator works
  • String/ expression: just like normal class attribute

Can not get a simple bootstrap modal to work

<div class="modal fade bs-example-modal-lg" id="{{'modal'+ cartModal.index}}">
  <div class="modal-dialog modal-lg" role="document">
    <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>
      <div class="modal-body">
          <div class="col-lg-6" >
            <p class="prodTitle" ng-bind="(cartModal.product.p_name|uppercase)"></p>
            <p class="price-para">
              <span class="currency-cls" ng-bind="cartModal.product.c_currency"></span>
              <span class="price-cls" ng-bind="cartModal.product.p_price"></span>
            <p class="select-color">
              <span ng-repeat="color in cartModal.product.p_available_options.colors">
                <button id="color-style" ng-click="cartModal.saveColor(color)" ng-style="{'background-color':color.hexcode}"></button>
            <p class="select-box">
              <span class="size-select-cls">
                SIZE:<select ng-init="items=cartModal.product.p_available_options.sizes" ng-model="cartModal.selectedSize" ng-options="item.code as
       for item in items"></select>
              <span class="qty">
                QTY:<input type="number"  min="1" ng-model="cartModal.selectedQty"/>
            <p class="edit-button">
              <button class="btn-primary btn-lg" data-dismiss="modal" ng-click=";cartModal.calculate()">EDIT</button>
          <div class="col-lg-6">
            <img ng-src="{{cartModal.product.imageSrc}}">

Unlink of file Failed. Should I try again?

this solution from here worked for me:

This is a Windows specific answer, so I'm aware that it's not relevant to you... I'm just including it for the benefit of future searchers.

In my case, it was because I was running Git from a non-elevated command line. "Run as Administrator" fixed it for me.

Comparing two strings in C?

You need to use strcmp:

strcmp(namet2, nameIt2)

Convert UTC/GMT time to local time

I had the problem with it being in a data set being pushed across the wire (webservice to client) that it would automatically change because the DataColumn's DateType field was set to local. Make sure you check what the DateType is if your pushing DataSets across.

If you don't want it to change, set it to Unspecified

C#: How do you edit items and subitems in a listview?

private void listView1_MouseDown(object sender, MouseEventArgs e)
    li = listView1.GetItemAt(e.X, e.Y);
    X = e.X;
    Y = e.Y;

private void listView1_MouseUp(object sender, MouseEventArgs e)
    int nStart = X;
    int spos = 0;
    int epos = listView1.Columns[1].Width;
    for (int i = 0; i < listView1.Columns.Count; i++)
        if (nStart > spos && nStart < epos)
            subItemSelected = i;

        spos = epos;
        epos += listView1.Columns[i].Width;
    li.SubItems[subItemSelected].Text = "9";

How to make a phone call programmatically?

protected void onCreate(Bundle savedInstanceState) {
   final Button button = (Button) findViewById(;
    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            String mobileNo = "123456789";
            String uri = "tel:" + mobileNo.trim();
            Intent intent = new Intent(Intent.ACTION_CALL);

Java Does Not Equal (!=) Not Working?

You need to use the method equals() when comparing a string, otherwise you're just comparing the object references to each other, so in your case you want:

if (!statusCheck.equals("success")) {

Export Postgresql table data using pgAdmin

  1. Right-click on your table and pick option Backup..
  2. On File Options, set Filepath/Filename and pick PLAIN for Format
  3. Ignore Dump Options #1 tab
  4. In Dump Options #2 tab, check USE INSERT COMMANDS
  5. In Dump Options #2 tab, check Use Column Inserts if you want column names in your inserts.
  6. Hit Backup button

How to read a file into vector in C++?

  //file name must be of the form filename.yourfileExtension
       std::vector<std::string> source;
bool getFileContent(std::string & fileName)
    if (fileName.substr(fileName.find_last_of(".") + 1) =="yourfileExtension")

        // Open the File
        std::ifstream in(fileName.c_str());

        // Check if object is valid
        if (!in)
            std::cerr << "Cannot open the File : " << fileName << std::endl;
            return false;
        std::string str;
        // Read the next line from File untill it reaches the end.
        while (std::getline(in, str))
            // Line contains string of length > 0 then save it in vector
            if (str.size() > 0)
        /*for (size_t i = 0; i < source.size(); i++)
        lexer(source[i], i);
        cout << source[i] << endl;
        //Close The File
        return true;
        std::cerr << ":VIP doe\'s not support this file type" << std::endl;
        std::cerr << "supported extensions is filename.yourfileExtension" << endl;

How to count string occurrence in string?

var temp = "This is a string.";_x000D_
console.log((temp.match(new RegExp("is", "g")) || []).length);

How do I convert a single character into it's hex ascii value in python

To use the hex encoding in Python 3, use

>>> import codecs
>>> codecs.encode(b"c", "hex")

In legacy Python, there are several other ways of doing this:

>>> hex(ord("c"))
>>> format(ord("c"), "x")
>>> "c".encode("hex")

How to change python version in anaconda spyder

You can open the preferences (multiple options):

  • keyboard shortcut Ctrl + Alt + Shift + P
  • Tools -> Preferences

And depending on the Spyder version you can change the interpreter in the Python interpreter section (Spyder 3.x):

enter image description here

or in the advanced Console section (Spyder 2.x):

enter image description here target _self v window.location.href?

Definitely the second method is preferred because you don't have the overhead of another function invocation:

window.location.href = "webpage.htm";

How can I check if a directory exists in a Bash shell script?

There are great solutions out there, but ultimately every script will fail if you're not in the right directory. So code like this:

if [ -d "$LINK_OR_DIR" ]; then
if [ -L "$LINK_OR_DIR" ]; then
    # It is a symlink!
    # Symbolic link specific commands go here
    rm "$LINK_OR_DIR"
    # It's a directory!
    # Directory command goes here
    rmdir "$LINK_OR_DIR"

will execute successfully only if at the moment of execution you're in a directory that has a subdirectory that you happen to check for.

I understand the initial question like this: to verify if a directory exists irrespective of the user's position in the file system. So using the command 'find' might do the trick:

dir=" "
echo "Input directory name to search for:"
read dir
find $HOME -name $dir -type d

This solution is good because it allows the use of wildcards, a useful feature when searching for files/directories. The only problem is that, if the searched directory doesn't exist, the 'find' command will print nothing to standard output (not an elegant solution for my taste) and will have nonetheless a zero exit. Maybe someone could improve on this.

Key error when selecting columns in pandas dataframe after read_csv

if you need to select multiple columns from dataframe use 2 pairs of square brackets eg.


SQL: How do I SELECT only the rows with a unique value on certain column?

I'm a fan of NOT EXISTS

SELECT DISTINCT contract, activity FROM table t1
  SELECT * FROM table t2
  WHERE t2.contract = t1.contract AND t2.activity != t1.activity

Replace a value in a data frame based on a conditional (`if`) statement

Short answer is:

junk$nm[junk$nm %in% "B"] <- "b"

Take a look at Index vectors in R Introduction (if you don't read it yet).

EDIT. As noticed in comments this solution works for character vectors so fail on your data.

For factor best way is to change level:

levels(junk$nm)[levels(junk$nm)=="B"] <- "b"

How to draw checkbox or tick mark in GitHub Markdown table?

There are very nice Emoji icons instructions available at

You can check them out. I hope you would find suitable icons for your writing.

Nice Emojis


Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server


    a int NOT NULL
    ,b smallint NOT NULL index IX_indexName nonclustered
    ,c smallint NOT NULL
    ,d smallint NOT NULL
    ,e smallint NOT NULL


As per T-SQL CREATE TABLE documentation, in 2014 the column definition supports defining an index:

<column_definition> ::=  
column_name <data_type>  
    [ <column_index> ]  

and <column_index> grammar is defined as:

<column_index> ::=   
    [ WITH ( <index_option> [ ,... n ] ) ]  
    [ ON { partition_scheme_name (column_name )   
         | filegroup_name  
         | default   
    [ FILESTREAM_ON { filestream_filegroup_name | partition_scheme_name | "NULL" } ]  

So a lot of what you can do as a separate statement can be done inline. I noticed include is not an option in this grammar so some things are not possible.

    a int NOT NULL
    ,b smallint NOT NULL index IX_indexName nonclustered
    ,c smallint NOT NULL
    ,d smallint NOT NULL
    ,e smallint NOT NULL

You can also have inline indexes defined as another line after columns, but within the create table statement, and this allows multiple columns in the index, but still no include clause:

< table_index > ::=   
      INDEX index_name [ CLUSTERED | NONCLUSTERED ]   
         (column_name [ ASC | DESC ] [ ,... n ] )   
    | INDEX index_name [ NONCLUSTERED ] COLUMNSTORE (column_name [ ,... n ] )  
    [ WITH ( <index_option> [ ,... n ] ) ]   
    [ ON { partition_scheme_name (column_name )   
         | filegroup_name  
         | default   
    [ FILESTREAM_ON { filestream_filegroup_name | partition_scheme_name | "NULL" } ]  

For example here we add an index on both columns c and d:

    a int NOT NULL
    ,b smallint NOT NULL index IX_MyTable_b nonclustered
    ,c smallint NOT NULL
    ,d smallint NOT NULL
    ,e smallint NOT NULL

    ,index IX_MyTable_c_d nonclustered (c,d)

Best way to encode text data for XML

Here is a single line solution using the XElements. I use it in a very small tool. I don't need it a second time so I keep it this way. (Its dirdy doug)

StrVal = (<x a=<%= StrVal %>>END</x>).ToString().Replace("<x a=""", "").Replace(">END</x>", "")

Oh and it only works in VB not in C#

How to insert special characters into a database?

Use this: htmlentities($_POST['field']);

Enough only. This for special character:

Use for CI htmlentities($this->input->post('control_name'));

How to create a inner border for a box in html?

.blackBox {_x000D_
    width: 100%;_x000D_
    height: 200px;_x000D_
    background-color: #000;_x000D_
    position: relative;_x000D_
    color: cyan;_x000D_
    padding: 20px;_x000D_
    box-sizing: border-box;_x000D_
.blackBox::before {_x000D_
 position: absolute;_x000D_
    border: 1px dotted #fff;_x000D_
    left: 10px;_x000D_
    right: 10px;_x000D_
    top: 10px;_x000D_
    bottom: 10px;_x000D_
    content: "";_x000D_
<!DOCTYPE html>_x000D_
<div class="blackBox">Created an inner border box. <br> Working fine all major browsers.</div>_x000D_

sql server Get the FULL month name from a date

         + RIGHT(CONVERT(VARCHAR(12), GETDATE(), 107), 9) AS [Month DD, YYYY]

OR Date without Comma Between date and year, you can use the following

           + ' ' + CAST(YEAR(GETDATE()) AS VARCHAR(4)) AS [Month DD YYYY]

How to crop an image using PIL?

(left, upper, right, lower) means two points,

  1. (left, upper)
  2. (right, lower)

with an 800x600 pixel image, the image's left upper point is (0, 0), the right lower point is (800, 600).

So, for cutting the image half:

from PIL import Image
img ="ImageName.jpg")

img_left_area = (0, 0, 400, 600)
img_right_area = (400, 0, 800, 600)

img_left = img.crop(img_left_area)
img_right = img.crop(img_right_area)

enter image description here

Coordinate System

The Python Imaging Library uses a Cartesian pixel coordinate system, with (0,0) in the upper left corner. Note that the coordinates refer to the implied pixel corners; the centre of a pixel addressed as (0, 0) actually lies at (0.5, 0.5).

Coordinates are usually passed to the library as 2-tuples (x, y). Rectangles are represented as 4-tuples, with the upper left corner given first. For example, a rectangle covering all of an 800x600 pixel image is written as (0, 0, 800, 600).

SVN "Already Locked Error"

I am not using AnkhSVN but got a similar problem after cancelling a Tortoise SVN update. It left two directories "already locked". Similar to Roman C's solution. Use Get lock to to lock one file in each directory that is "already locked" and then release those locks, then do a cleanup on the highest directory. That seemed to fix the problem.

Is there a way to detect if a browser window is not currently active?

There are 3 typical methods used to determine if the user can see the HTML page, however none of them work perfectly:

  • The W3C Page Visibility API is supposed to do this (supported since: Firefox 10, MSIE 10, Chrome 13). However, this API only raises events when the browser tab is fully overriden (e.g. when the user changes from one tab to another one). The API does not raise events when the visibility cannot be determined with 100% accuracy (e.g. Alt+Tab to switch to another application).

  • Using focus/blur based methods gives you a lot of false positive. For example, if the user displays a smaller window on top of the browser window, the browser window will lose the focus (onblur raised) but the user is still able to see it (so it still need to be refreshed). See also

  • Relying on user activity (mouse move, clicks, key typed) gives you a lot of false positive too. Think about the same case as above, or a user watching a video.

In order to improve the imperfect behaviors described above, I use a combination of the 3 methods: W3C Visibility API, then focus/blur and user activity methods in order to reduce the false positive rate. This allows to manage the following events:

  • Changing browser tab to another one (100% accuracy, thanks to the W3C Page Visibility API)
  • Page potentially hidden by another window, e.g. due to Alt+Tab (probabilistic = not 100% accurate)
  • User attention potentially not focused on the HTML page (probabilistic = not 100% accurate)

This is how it works: when the document lose the focus, the user activity (such as mouse move) on the document is monitored in order to determine if the window is visible or not. The page visibility probability is inversely proportional to the time of the last user activity on the page: if the user makes no activity on the document for a long time, the page is most probably not visible. The code below mimics the W3C Page Visibility API: it behaves the same way but has a small false positive rate. It has the advantage to be multibrowser (tested on Firefox 5, Firefox 10, MSIE 9, MSIE 7, Safari 5, Chrome 9).

    <div id="x"></div>

    Registers the handler to the event for the given object.
    @param obj the object which will raise the event
    @param evType the event type: click, keypress, mouseover, ...
    @param fn the event handler function
    @param isCapturing set the event mode (true = capturing event, false = bubbling event)
    @return true if the event handler has been attached correctly
    function addEvent(obj, evType, fn, isCapturing){
      if (isCapturing==null) isCapturing=false; 
      if (obj.addEventListener){
        // Firefox
        obj.addEventListener(evType, fn, isCapturing);
        return true;
      } else if (obj.attachEvent){
        // MSIE
        var r = obj.attachEvent('on'+evType, fn);
        return r;
      } else {
        return false;

    // register to the potential page visibility change
    addEvent(document, "potentialvisilitychange", function(event) {
      document.getElementById("x").innerHTML+="potentialVisilityChange: potentialHidden="+document.potentialHidden+", document.potentiallyHiddenSince="+document.potentiallyHiddenSince+" s<br>";

    // register to the W3C Page Visibility API
    var hidden=null;
    var visibilityChange=null;
    if (typeof document.mozHidden !== "undefined") {
    } else if (typeof document.msHidden !== "undefined") {
    } else if (typeof document.webkitHidden!=="undefined") {
    } else if (typeof document.hidden !=="hidden") {
    if (hidden!=null && visibilityChange!=null) {
      addEvent(document, visibilityChange, function(event) {
        document.getElementById("x").innerHTML+=visibilityChange+": "+hidden+"="+document[hidden]+"<br>";

    var potentialPageVisibility = {
      pageVisibilityChangeThreshold:3*3600, // in seconds
      init:function() {
        function setAsNotHidden() {
          var dispatchEventRequired=document.potentialHidden;
          if (dispatchEventRequired) dispatchPageVisibilityChangeEvent();

        function initPotentiallyHiddenDetection() {
          if (!hasFocusLocal) {
            // the window does not has the focus => check for  user activity in the window
            lastActionDate=new Date();
            if (timeoutHandler!=null) {
            timeoutHandler = setTimeout(checkPageVisibility, potentialPageVisibility.pageVisibilityChangeThreshold*1000+100); // +100 ms to avoid rounding issues under Firefox

        function dispatchPageVisibilityChangeEvent() {
          var evt = document.createEvent("Event");
          evt.initEvent("potentialvisilitychange", true, true);

        function checkPageVisibility() {
          var potentialHiddenDuration=(hasFocusLocal || lastActionDate==null?0:Math.floor((new Date().getTime()-lastActionDate.getTime())/1000));
          if (potentialHiddenDuration>=potentialPageVisibility.pageVisibilityChangeThreshold && !document.potentialHidden) {
            // page visibility change threshold raiched => raise the even

        var lastActionDate=null;
        var hasFocusLocal=true;
        var hasMouseOver=true;
        var timeoutHandler = null;

        addEvent(document, "pageshow", function(event) {
        addEvent(document, "pagehide", function(event) {
        addEvent(window, "pageshow", function(event) {
          document.getElementById("x").innerHTML+="pageshow/win:<br>"; // raised when the page first shows
        addEvent(window, "pagehide", function(event) {
          document.getElementById("x").innerHTML+="pagehide/win:<br>"; // not raised
        addEvent(document, "mousemove", function(event) {
          lastActionDate=new Date();
        addEvent(document, "mouseover", function(event) {
        addEvent(document, "mouseout", function(event) {
        addEvent(window, "blur", function(event) {
        addEvent(window, "focus", function(event) {

    potentialPageVisibility.pageVisibilityChangeThreshold=4; // 4 seconds for testing

Since there is currently no working cross-browser solution without false positive, you should better think twice about disabling periodical activity on your web site.

Python object deleting itself

Indeed, Python does garbage collection through reference counting. As soon as the last reference to an object falls out of scope, it is deleted. In your example:

a = A()

I don't believe there's any way for variable 'a' to implicitly set itself to None.

z-index not working with position absolute

I faced this issue a lot when using position: absolute;, I faced this issue by using position: relative in the child element. don't need to change position: absolute to relative, just need to add in the child element look into the beneath two examples:

let toggle = document.getElementById('toggle')

toggle.addEventListener("click", () => {
.container {
  width: 60px;
  height: 22px;
  background: #333;
  border-radius: 20px;
  position: relative;
  cursor: pointer;


.change .slide {
  transform: translateX(33px);

.slide {
  transition: 0.5s;
  width: 20px;
  height: 20px;
  background: #fff;
  border-radius: 20px;
  margin: 2px 2px;
  z-index: 100;

.dot {
  width: 10px;
  height: 16px;
  background: red;
  position: absolute;
  top: 4px;
  right: 5px;
  z-index: 1;
<div class="container" id="toggle">
  <div class="slide"></div>
  <div class="dot"></div>

This's how it can be fixed using position relative:

let toggle = document.getElementById('toggle')

toggle.addEventListener("click", () => {
.container {
  width: 60px;
  height: 22px;
  background: #333;
  border-radius: 20px;
  position: relative;
  cursor: pointer;


.change .slide {
  transform: translateX(33px);

.slide {
  transition: 0.5s;
  width: 20px;
  height: 20px;
  background: #fff;
  border-radius: 20px;
  margin: 2px 2px;
  z-index: 100;
  // Just add position relative;
  position: relative;

.dot {
  width: 10px;
  height: 16px;
  background: red;
  position: absolute;
  top: 4px;
  right: 5px;
  z-index: 1;
<div class="container" id="toggle">
  <div class="slide"></div>
  <div class="dot"></div>

Sandbox here

How to retrieve SQL result column value using column name in Python?

Of course there is. In Python 2.7.2+...

import MySQLdb as mdb
con =  mdb.connect('localhost', 'user', 'password', 'db');
cur = con.cursor()
cur.execute('SELECT Foo, Bar FROM Table')
for i in range(int(cur.numrows)):
    foo, bar = cur.fetchone()
    print 'foo = %s' % foo
    print 'bar = %s' % bar

How do I load external fonts into an HTML document?

CSS3 offers a way to do it with the @font-face rule.

Here is a number of different ways which will work in browsers that don't support the @font-face rule.

TypeError: unhashable type: 'dict'

You're trying to use a dict as a key to another dict or in a set. That does not work because the keys have to be hashable. As a general rule, only immutable objects (strings, integers, floats, frozensets, tuples of immutables) are hashable (though exceptions are possible). So this does not work:

>>> dict_key = {"a": "b"}
>>> some_dict[dict_key] = True
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'dict'

To use a dict as a key you need to turn it into something that may be hashed first. If the dict you wish to use as key consists of only immutable values, you can create a hashable representation of it like this:

>>> key = frozenset(dict_key.items())

Now you may use key as a key in a dict or set:

>>> some_dict[key] = True
>>> some_dict
{frozenset([('a', 'b')]): True}

Of course you need to repeat the exercise whenever you want to look up something using a dict:

>>> some_dict[dict_key]                     # Doesn't work
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'dict'
>>> some_dict[frozenset(dict_key.items())]  # Works

If the dict you wish to use as key has values that are themselves dicts and/or lists, you need to recursively "freeze" the prospective key. Here's a starting point:

def freeze(d):
    if isinstance(d, dict):
        return frozenset((key, freeze(value)) for key, value in d.items())
    elif isinstance(d, list):
        return tuple(freeze(value) for value in d)
    return d

How do I import a .sql file in mysql database using PHP?

As we all know MySQL was deprecated in PHP 5.5.0, and it was removed in PHP 7.0.0 ref so I have converted accepted answer to mysqli.

// Name of the file
$filename = 'db.sql';
// MySQL host
$mysql_host = 'localhost';
// MySQL username
$mysql_username = 'root';
// MySQL password
$mysql_password = '123456';
// Database name
$mysql_database = 'mydb';

$connection = mysqli_connect($mysql_host,$mysql_username,$mysql_password,$mysql_database) or die(mysqli_error($connection));

// Temporary variable, used to store current query
$templine = '';
// Read in entire file
$lines = file($filename);
// Loop through each line
foreach ($lines as $line)
// Skip it if it's a comment
if (substr($line, 0, 2) == '--' || $line == '')

// Add this line to the current segment
$templine .= $line;
// If it has a semicolon at the end, it's the end of the query
if (substr(trim($line), -1, 1) == ';')
    // Perform the query
    mysqli_query($connection,$templine) or print('Error performing query \'<strong>' . $templine . '\': ' . mysqli_error($connection) . '<br /><br />');
    // Reset temp variable to empty
    $templine = '';
 echo "Tables imported successfully";

Fatal error: Call to a member function prepare() on null

@delato468 comment must be listed as a solution as it worked for me.

In addition to defining the parameter, the user must pass it too at the time of calling the function

fetch_data(PDO $pdo, $cat_id)

Count(*) vs Count(1) - SQL Server

In all RDBMS, the two ways of counting are equivalent in terms of what result they produce. Regarding performance, I have not observed any performance difference in SQL Server, but it may be worth pointing out that some RDBMS, e.g. PostgreSQL 11, have less optimal implementations for COUNT(1) as they check for the argument expression's nullability as can be seen in this post.

I've found a 10% performance difference for 1M rows when running:

-- Faster

-- 10% slower

AttributeError: 'numpy.ndarray' object has no attribute 'append'

Use numpy.concatenate(list1 , list2) or numpy.append() Look into the thread at Append a NumPy array to a NumPy array.

JOIN queries vs multiple queries

There are several factors which means there is no binary answer. The question of what is best for performance depends on your environment. By the way, if your single select with an identifier is not sub-second, something may be wrong with your configuration.

The real question to ask is how do you want to access the data. Single selects support late-binding. For example if you only want employee information, you can select from the Employees table. The foreign key relationships can be used to retrieve related resources at a later time and as needed. The selects will already have a key to point to so they should be extremely fast, and you only have to retrieve what you need. Network latency must always be taken into account.

Joins will retrieve all of the data at once. If you are generating a report or populating a grid, this may be exactly what you want. Compiled and optomized joins are simply going to be faster than single selects in this scenario. Remember, Ad-hoc joins may not be as fast--you should compile them (into a stored proc). The speed answer depends on the execution plan, which details exactly what steps the DBMS takes to retrieve the data.

How do you get a directory listing in C?

The strict answer is "you can't", as the very concept of a folder is not truly cross-platform.

On MS platforms you can use _findfirst, _findnext and _findclose for a 'c' sort of feel, and FindFirstFile and FindNextFile for the underlying Win32 calls.

Here's the C-FAQ answer:

In Powershell what is the idiomatic way of converting a string to an int?

Using .net

[int]$b = $null #used after as refence
[int32]::TryParse($a , [ref]$b ) # test if is possible to cast and put parsed value in reference variable

IsPublic IsSerial Name                                     BaseType
-------- -------- ----                                     --------
True     True     Int32                                    System.ValueType

note this (powershell coercing feature)

$a = "10"
$a + 1 #second value is evaluated as [string]

11 + $a # second value is evaluated as [int]

Replace one character with another in Bash

Use parameter substitution:

string=${string// /.}

Convert laravel object to array

this worked for me in laravel 5.4

$partnerProfileIds = DB::table('partner_profile_extras')->get()->pluck('partner_profile_id');
$partnerProfileIdsArray = $partnerProfileIds->all();


array:4 [?
  0 => "8219c678-2d3e-11e8-a4a3-648099380678"
  1 => "28459dcb-2d3f-11e8-a4a3-648099380678"
  2 => "d5190f8e-2c31-11e8-8802-648099380678"
  3 => "6d2845b6-2d3e-11e8-a4a3-648099380678"

Parse String date in (yyyy-MM-dd) format

You are creating a Date object, which is a representation of a certain point in the timeline. This means that it will have all the parts necessary to represent it correctly, including minutes and seconds and so on. Because you initialize it from a string containing only a part of the date, the missing data will be defaulted.

I assume you are then "printing" this Date object, but without actually specifying a format like you did when parsing it. Use the same SimpleDateFormat but call the reverse method, format(Date) as Holger suggested

Jackson enum Serializing and DeSerializer

Actual Answer:

The default deserializer for enums uses .name() to deserialize, so it's not using the @JsonValue. So as @OldCurmudgeon pointed out, you'd need to pass in {"event": "FORGOT_PASSWORD"} to match the .name() value.

An other option (assuming you want the write and read json values to be the same)...

More Info:

There is (yet) another way to manage the serialization and deserialization process with Jackson. You can specify these annotations to use your own custom serializer and deserializer:

@JsonSerialize(using = MySerializer.class)
@JsonDeserialize(using = MyDeserializer.class)
public final class MyClass {

Then you have to write MySerializer and MyDeserializer which look like this:


public final class MySerializer extends JsonSerializer<MyClass>
    public void serialize(final MyClass yourClassHere, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException
        // here you'd write data to the stream with gen.write...() methods



public final class MyDeserializer extends<MyClass>
    public MyClass deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException
        // then you'd do something like parser.getInt() or whatever to pull data off the parser
        return null;


Last little bit, particularly for doing this to an enum JsonEnum that serializes with the method getYourValue(), your serializer and deserializer might look like this:

public void serialize(final JsonEnum enumValue, final JsonGenerator gen, final SerializerProvider serializer) throws IOException, JsonProcessingException

public JsonEnum deserialize(final JsonParser parser, final DeserializationContext context) throws IOException, JsonProcessingException
    final String jsonValue = parser.getText();
    for (final JsonEnum enumValue : JsonEnum.values())
        if (enumValue.getYourValue().equals(jsonValue))
            return enumValue;
    return null;

cleanup php session files

cd to sessions directory and then:

1) View sessions older than 40 min: find . -amin +40 -exec stat -c "%n %y" {} \;

2) Remove sessions older than 40 min: find . -amin +40 -exec rm {} \;

How can I use UIColorFromRGB in Swift?

Here's a Swift version of that function (for getting a UIColor representation of a UInt value):

func UIColorFromRGB(rgbValue: UInt) -> UIColor {
    return UIColor(
        red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
        green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
        blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
        alpha: CGFloat(1.0)

view.backgroundColor = UIColorFromRGB(0x209624)

Applying CSS styles to all elements inside a DIV

If you're looking for a shortcut for writing out all of your selectors, then a CSS Preprocessor (Sass, LESS, Stylus, etc.) can do what you're looking for. However, the generated styles must be valid CSS.


#applyCSS {
    .ui-bar-a {
       color: blue;
    .ui-bar-a .ui-link-inherit {
       color: orange;
    background: #CCC;

Generated CSS:

#applyCSS {
  background: #CCC;

#applyCSS .ui-bar-a {
  color: blue;

#applyCSS .ui-bar-a .ui-link-inherit {
  color: orange;

How to get a cookie from an AJAX response?

You're looking for a response header of Set-Cookie:


It won't work with HTTPOnly cookies though.


According to the XMLHttpRequest Level 1 and XMLHttpRequest Level 2, this particular response headers falls under the "forbidden" response headers that you can obtain using getResponseHeader(), so the only reason why this could work is basically a "naughty" browser.

Which are more performant, CTE or temporary tables?

I just tested this- both CTE and non-CTE (where the query was typed out for every union instance) both took ~31 seconds. CTE made the code much more readable though- cut it down from 241 to 130 lines which is very nice. Temp table on the other hand cut it down to 132 lines, and took FIVE SECONDS to run. No joke. all of this testing was cached- the queries were all run multiple times before.

Java system properties and environment variables

I think the difference between the two boils down to access. Environment variables are accessible by any process and Java system properties are only accessible by the process they are added to.

Also as Bohemian stated, env variables are set in the OS (however they 'can' be set through Java) and system properties are passed as command line options or set via setProperty().

Convert date time string to epoch in Bash

What you're looking for is date --date='06/12/2012 07:21:22' +"%s". Keep in mind that this assumes you're using GNU coreutils, as both --date and the %s format string are GNU extensions. POSIX doesn't specify either of those, so there is no portable way of making such conversion even on POSIX compliant systems.

Consult the appropriate manual page for other versions of date.

Note: bash --date and -d option expects the date in US or ISO8601 format, i.e. mm/dd/yyyy or yyyy-mm-dd, not in UK, EU, or any other format.

How can I show/hide component with JSF?

Generally, you need to get a handle to the control via its clientId. This example uses a JSF2 Facelets view with a request-scope binding to get a handle to the other control:

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns=""
      <h:button value="toggle"
               onclick="toggle('#{}'); return false;" />
      <h:inputText binding="#{}" id="x" style="display: block" />
    <script type="text/javascript">
      function toggle(id) {
        var element = document.getElementById(id);
        if( == 'block') {
 = 'none';
        } else {
 = 'block'

Exactly how you do this will depend on the version of JSF you're working on. See this blog post for older JSF versions: JSF: working with component identifiers.

Xcode 5 and iOS 7: Architecture and Valid architectures

When you set 64-bit the resulting binary is a "Fat" binary, which contains all three Mach-O images bundled with a thin fat header. You can see that using otool or jtool. You can check out some fat binaries included as part of the iOS 7.0 SDK, for example the AVFoundation Framework, like so:

% cd  /Developer/Platforms/iPhoneOS.platform/DeviceSupport/7.0\ \(11A465\)/Symbols/System/Library/Frameworks/AVFoundation.framework/

%otool -V -f AVFoundation                                                                     9:36
Fat headers
fat_magic FAT_MAGIC
nfat_arch 3
architecture arm64     # The 64-bit version (A7)
    cputype CPU_TYPE_ARM64
    cpusubtype CPU_SUBTYPE_ARM64_ALL
    capabilities 0x0
    offset 16384
    size 2329888
    align 2^14 (16384)
architecture armv7        # A5X - packaged after the arm64version
    cputype CPU_TYPE_ARM
    cpusubtype CPU_SUBTYPE_ARM_V7
    capabilities 0x0
    offset 2359296
    size 2046336
    align 2^14 (16384)
architecture armv7s       # A6 - packaged after the armv7 version
    cputype CPU_TYPE_ARM
    cpusubtype CPU_SUBTYPE_ARM_V7S
    capabilities 0x0
    offset 4407296
    size 2046176
    align 2^14 (16384)

As for the binary itself, it uses the ARM64 bit instruction set, which is (mostly compatible with 32-bit, but) a totally different instruction set. This is especially important for graphics program (using NEON instructions and registers). Likewise, the CPU has more registers, which makes quite an impact on program speed. There's an interesting discussion in on whether or not this makes a difference; benchmarking tests have so far clearly indicated that it does.

Using otool -tV will dump the assembly (if you have XCode 5 and later), and then you can see the instruction set differences for yourself. Most (but not all) developers will remain agnostic to the changes, as for the most part they do not directly affect Obj-C (CG* APIs notwithstanding), and have to do more with low level pointer handling. The compiler will work its magic and optimizations.

How to create a custom scrollbar on a div (Facebook style)

This link should get you started. Long story short, a div that has been styled to look like a scrollbar is used to catch click-and-drag events. Wired up to these events are methods that scroll the contents of another div which is set to an arbitrary height and typically has a css rule of overflow:scroll (there are variants on the css rules but you get the idea).

I'm all about the learning experience -- but after you've learned how it works, I recommend using a library (of which there are many) to do it. It's one of those "don't reinvent" things...

Best way to compare 2 XML documents in Java

Since you say "semantically equivalent" I assume you mean that you want to do more than just literally verify that the xml outputs are (string) equals, and that you'd want something like

<foo> some stuff here</foo></code>


<foo>some stuff here</foo></code>

do read as equivalent. Ultimately it's going to matter how you're defining "semantically equivalent" on whatever object you're reconstituting the message from. Simply build that object from the messages and use a custom equals() to define what you're looking for.

How to check whether an object has certain method/property?

To avoid AmbiguousMatchException, I would rather say

objectToCheck.GetType().GetMethods().Count(m => m.Name == method) > 0

How to block until an event is fired in c#

If you're happy to use the Microsoft Reactive Extensions, then this can work nicely:

public class Foo
    public delegate void MyEventHandler(object source, MessageEventArgs args);
    public event MyEventHandler _event;
    public string ReadLine()
        return Observable
            .FromEventPattern<MyEventHandler, MessageEventArgs>(
                h => this._event += h,
                h => this._event -= h)
            .Select(ep => ep.EventArgs.Message)
    public void SendLine(string message)
        _event(this, new MessageEventArgs() { Message = message });

public class MessageEventArgs : EventArgs
    public string Message;

I can use it like this:

var foo = new Foo();

        () => foo.SendLine("Bar!"));

var resp = foo.ReadLine();


I needed to call the SendLine message on a different thread to avoid locking, but this code shows that it works as expected.

pg_config executable not found

On Windows, You may want to install the Windows port of Psycopg, which is recommended in psycopg's documentation.

Convert MFC CString to integer

you can also use good old sscanf.

CString s;
int i;
int j = _stscanf(s, _T("%d"), &i);
if (j != 1)
   // tranfer didn't work

Detecting iOS / Android Operating system

You can also Achieve this with user agent on php:

$userAgent = strtolower($_SERVER['HTTP_USER_AGENT']);

if(stripos($userAgent,'android') !== false) { // && stripos($userAgent,'mobile') !== false) {



Remove NaN from pandas series

If you have a pandas serie with NaN, and want to remove it (without loosing index):

serie = serie.dropna()

# create data for example
data = np.array(['g', 'e', 'e', 'k', 's']) 
ser = pd.Series(data)
ser.replace('e', np.NAN)

0      g
1    NaN
2    NaN
3      k
4      s
dtype: object

# the code
ser = ser.dropna()

0    g
3    k
4    s
dtype: object

How to enable authentication on MongoDB through Docker?

I have hard time when trying to

  • Create other db than admin
  • Add new users and enable authentication to the db above

So I made 2020 answer here

My directory looks like this

+-- docker-compose.yml
+-- mongo-entrypoint
    +-- entrypoint.js

My docker-compose.yml looks like this

version: '3.4'
    # If you need to connect to your db from outside this container 
    network_mode: host
    image: mongo:4.2
      - "27017:27017"
      - "$PWD/mongo-entrypoint/:/docker-entrypoint-initdb.d/"
    command: mongod

Please change admin and pass with your need.

Inside mongo-entrypoint, I have entrypoint.js file with this content:

var db = connect("mongodb://admin:pass@localhost:27017/admin");

db = db.getSiblingDB('new_db'); // we can not use "use" statement here to switch db

        user: "user",
        pwd: "pass",
        roles: [ { role: "readWrite", db: "new_db"} ],
        passwordDigestor: "server",

Here again you need to change admin:pass to your root mongo credentials in your docker-compose.yml that you stated before. In additional you need to change new_db, user, pass to your new database name and credentials that you need.

Now you can:

docker-compose up -d

And connect to this db from localhost, please note that I already have mongo cli, you can install it or you can exec to the container above to use mongo command:

mongo new_db -u user -p pass

Or you can connect from other computer

mongo host:27017/new_db -u user -p pass

My git repository:

Hope it can help someone, I lost my afternoon for this ;)

How to move git repository with all branches from bitbucket to github?

There is the Importing a repository with GitHub Importer

If you have a project hosted on another version control system as Mercurial, you can automatically import it to GitHub using the GitHub Importer tool.

  1. In the upper-right corner of any page, click , and then click Import repository.
  2. Under "Your old repository's clone URL", type the URL of the project you want to import.
  3. Choose your user account or an organization to own the repository, then type a name for the repository on GitHub.
  4. Specify whether the new repository should be public or private.
    • Public repositories are visible to any user on GitHub, so you can benefit from GitHub's collaborative community.
    • Public or private repository radio buttonsPrivate repositories are only available to the repository owner, as well as any collaborators you choose to share with.
  5. Review the information you entered, then click Begin import.

You'll receive an email when the repository has been completely imported.


How to implement WiX installer upgrade?

I would suggest having a look at Alex Shevchuk's tutorial. He explains "major upgrade" through WiX with a good hands-on example at From MSI to WiX, Part 8 - Major Upgrade.

Responsively change div size keeping aspect ratio

You can do this using pure CSS; no JavaScript needed. This utilizes the (somewhat counterintuitive) fact that padding-top percentages are relative to the containing block's width. Here's an example:

.wrapper {_x000D_
  width: 50%;_x000D_
  /* whatever width you want */_x000D_
  display: inline-block;_x000D_
  position: relative;_x000D_
.wrapper:after {_x000D_
  padding-top: 56.25%;_x000D_
  /* 16:9 ratio */_x000D_
  display: block;_x000D_
  content: '';_x000D_
.main {_x000D_
  position: absolute;_x000D_
  top: 0;_x000D_
  bottom: 0;_x000D_
  right: 0;_x000D_
  left: 0;_x000D_
  /* fill parent */_x000D_
  background-color: deepskyblue;_x000D_
  /* let's see it! */_x000D_
  color: white;_x000D_
<div class="wrapper">_x000D_
  <div class="main">_x000D_
    This is your div with the specified aspect ratio._x000D_

How can I disable the bootstrap hover color for links?

I am not a Bootstrap expert, but it sounds to me that you should define a new class called nohover (or something equivalent) then in your link code add the class as the last attribute value:

<a class="green nohover" href="#">green text</a>
<a class="yellow nohover" href="#">yellow text</a>

Then in your Bootstrap LESS/CSS file, define nohover (using the JSFiddle example above):

a:hover { color: red  }
/* Green */  { color: green; }
/* Yellow */
a.yellow  { color: yellow; }
a.nohover:hover { color: none;  }

Forked the JSFiddle here:

Cannot use mkdir in home directory: permission denied (Linux Lubuntu)

you can try writing the command using 'sudo':

sudo mkdir DirName

Is it bad practice to use break to exit a loop in Java?

There are a number of common situations for which break is the most natural way to express the algorithm. They are called "loop-and-a-half" constructs; the paradigm example is

while (true) {
    item =;
    if (item == EOF)

If you can't use break for this you have to repeat yourself instead:

item =;
while (item != EOF) {
    item =;

It is generally agreed that this is worse.

Similarly, for continue, there is a common pattern that looks like this:

for (item in list) {
    if (ignore_p(item))
    if (trivial_p(item)) {

This is often more readable than the alternative with chained else if, particularly when process_complicated is more than just one function call.

Further reading: Loop Exits and Structured Programming: Reopening the Debate

How to use OpenCV SimpleBlobDetector

You may store the parameters for the blob detector in a file, but this is not necessary. Example:

// set up the parameters (check the defaults in opencv's code in blobdetector.cpp)
cv::SimpleBlobDetector::Params params;
params.minDistBetweenBlobs = 50.0f;
params.filterByInertia = false;
params.filterByConvexity = false;
params.filterByColor = false;
params.filterByCircularity = false;
params.filterByArea = true;
params.minArea = 20.0f;
params.maxArea = 500.0f;
// ... any other params you don't want default value

// set up and create the detector using the parameters
cv::SimpleBlobDetector blob_detector(params);
// or cv::Ptr<cv::SimpleBlobDetector> detector = cv::SimpleBlobDetector::create(params)

// detect!
vector<cv::KeyPoint> keypoints;
blob_detector.detect(image, keypoints);

// extract the x y coordinates of the keypoints: 

for (int i=0; i<keypoints.size(); i++){
    float X = keypoints[i].pt.x; 
    float Y = keypoints[i].pt.y;

Get the directory from a file path in java (android)

Yes. First, construct a File representing the image path:

File file = new File(a);

If you're starting from a relative path:

file = new File(file.getAbsolutePath());

Then, get the parent:

String dir = file.getParent();

Or, if you want the directory as a File object,

File dirAsFile = file.getParentFile();

How to parse a string into a nullable int

I feel my solution is a very clean and nice solution:

public static T? NullableParse<T>(string s) where T : struct
        return (T)typeof(T).GetMethod("Parse", new[] {typeof(string)}).Invoke(null, new[] { s });
    catch (Exception)
        return null;

This is of course a generic solution which only require that the generics argument has a static method "Parse(string)". This works for numbers, boolean, DateTime, etc.

I just assigned a variable, but echo $variable shows something else

Additional to putting the variable in quotation, one could also translate the output of the variable using tr and converting spaces to newlines.

$ echo $var | tr " " "\n"

Although this is a little more convoluted, it does add more diversity with the output as you can substitute any character as the separator between array variables.

How to disable registration new users in Laravel

Method 1 for version 5.3

In laravel 5.3 don't have AuthController. to disable register route you should change in constructor of RegisterController like this:

You can change form:

public function __construct()




use Illuminate\Support\Facades\Redirect;

public function __construct()



Note: for use Redirect don't forget to user Redirect; So user access to https://host_name/register it's redirect to "/".

Method 2 for version 5.3

When we use php artisan make:auth it's added Auth::route(); automatically. Please Override Route in /routes/web.php. You can change it's like this: * you need to comment this line: Auth::routes();


| Web Routes
| This file is where you may define all of the routes that are handled
| by your application. Just tell Laravel the URIs it should respond
| to using a Closure or controller method. Build something great!

// Auth::routes();
Route::get('/login', 'Auth\LoginController@showLoginForm' );
Route::post('/login', 'Auth\LoginController@login');
Route::post('/logout', 'Auth\LoginController@logout');

Route::get('/home', 'HomeController@index');

Thanks! I hope it's can solve your problems.

How to convert a List<String> into a comma separated string without iterating List explicitly

Join / concat & Split functions on ArrayList:

To Join /concat all elements of arraylist with comma (",") to String.

List<String> ids = new ArrayList<String>();
String allIds = TextUtils.join(",", ids);
Log.i("Result", allIds);

To split all elements of String to arraylist with comma (",").

String allIds = "1,2,3,4";
String[] allIdsArray = TextUtils.split(allIds, ",");
ArrayList<String> idsList = new ArrayList<String>(Arrays.asList(allIdsArray));
for(String element : idsList){
    Log.i("Result", element);


How do I set up curl to permanently use a proxy?

Curl will look for a .curlrc file in your home folder when it starts. You can create (or edit) this file and add this line:

proxy =

Command to open file with git

To open a file in Sublime Text,

Here is an example for opening a sample text file in Sublime Text editor

subl <filename>.txt

subl is previously created as an alias name,containing the directory file, using the "echo" command in Git Bash shell.

JavaScript - XMLHttpRequest, Access-Control-Allow-Origin errors

I've gotten same problem. The servers logs showed:

DEBUG: <-- origin: null

I've investigated that and it occurred that this is not populated when I've been calling from file from local drive. When I've copied file to the server and used it from server - the request worked perfectly fine

Requested registry access is not allowed

As a temporary fix, users can right click the utility and select "Run as administrator."

Why is `input` in Python 3 throwing NameError: name... is not defined

I got the same error. In the terminal when I typed "python", with this command, python2 was tring to run python3 code, because the is written python3. It runs correctly when I type "python3" in the terminal. I hope this works for you too.

jQuery: using a variable as a selector

You're thinking too complicated. It's actually just $('#'+openaddress).

Convert Enumeration to a Set/List

There is a simple example of convert enumeration to list. for this i used Collections.list(enum) method.

public class EnumerationToList {

    public static void main(String[] args) {
        Vector<String> vt = new Vector<String>();

        Enumeration<String> enm = vt.elements();
        List<String> ll = Collections.list(enm);
        System.out.println("List elements: " + ll);


Reference : How to convert enumeration to list

How to get sp_executesql result into a variable?

This worked for me:


DECLARE @tbl Table (
    Id int,
    Account varchar(50),
    Amount int

-- Lots of code to Create my dynamic sql statement

insert into @tbl EXEC sp_executesql @SQL

select * from @tbl

Python socket receive - incoming packets always have a different size

You can alternatively use recv(x_bytes, socket.MSG_WAITALL), which seems to work only on Unix, and will return exactly x_bytes.

Toolbar overlapping below status bar

According google docs ,we should not use fitsSystemWindows attribute in app theme, it is intended to use in layout files. Using in themes can causes problem in toast messages .

Check Issue here & example of problem caused here

<item name="android:fitsSystemWindows">true</item>

Example of using correct way and which works fine with windowTranslucentStatus as well.

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



<include layout="@layout/toolbar"

    app:menu="@menu/navigation_drawer_menu" />


What is the difference between float and double?

The built-in comparison operations differ as in when you compare 2 numbers with floating point, the difference in data type (i.e. float or double) may result in different outcomes.

Adding three months to a date in PHP

The following should work, but you may need to change the format:

echo date('l F jS, Y (m-d-Y)', strtotime('+3 months', strtotime($DateToAdjust)));

jQuery remove selected option from this

this isn't a css selector. you can avoid spelling the id of this by passing it as a context:

$('option:selected', this).remove();

How to force maven update?

I had this problem for a different reason. I went to the maven repository looking for the latest version of spring core, which at the time was 5.0.0.M3/ The repository showed me this entry for my pom.xml:

<!-- -->

Naive fool that I am, I assumed that the comment was telling me that the jar is located in the default repository.

However, after a lot of head-banging, I saw a note just below the xml saying "Note: this artifact it located at Alfresco Public repository ("

So the comment in the XML is completely misleading. The jar is located in another archive, which was why Maven couldn't find it!

What is float in Java?

In Java, when you type a decimal number as 3.6, its interpreted as a double. double is a 64-bit precision IEEE 754 floating point, while floatis a 32-bit precision IEEE 754 floating point. As a float is less precise than a double, the conversion cannot be performed implicitly.

If you want to create a float, you should end your number with f (i.e.: 3.6f).

For more explanation, see the primitive data types definition of the Java tutorial.

SASS - use variables across multiple files

You can do it like this:

I have a folder named utilities and inside that I have a file named _variables.scss

in that file i declare variables like so:

$black: #000;
$white: #fff;

then I have the style.scss file in which i import all of my other scss files like this:

// Utilities
@import "utilities/variables";

// Base Rules
@import "base/normalize";
@import "base/global";

then, within any of the files I have imported, I should be able to access the variables I have declared.

Just make sure you import the variable file before any of the others you would like to use it in.

HttpServletRequest to complete URL

HttpUtil being deprecated, this is the correct method

StringBuffer url = req.getRequestURL();
String queryString = req.getQueryString();
if (queryString != null) {
String requestURL = url.toString();

How to access parent scope from within a custom directive *with own scope* in AngularJS?

Having tried everything, I finally came up with a solution.

Just place the following in your template:

{{currentDirective.attr = parentDirective.attr; ''}}

It just writes the parent scope attribute/variable you want to access to the current scope.

Also notice the ; '' at the end of the statement, it's to make sure there's no output in your template. (Angular evaluates every statement, but only outputs the last one).

It's a bit hacky, but after a few hours of trial and error, it does the job.

Getting scroll bar width using JavaScript

// offsetWidth includes width of scroll bar and clientWidth doesn't. As rule, it equals 14-18px. so:

 var scrollBarWidth = element.offsetWidth - element.clientWidth;

Wait until an HTML5 video loads

you can use preload="none" in the attribute of video tag so the video will be displayed only when user clicks on play button.

<video preload="none">

How to put attributes via XElement

Add XAttribute in the constructor of the XElement, like

new XElement("Conn", new XAttribute("Server", comboBox1.Text));

You can also add multiple attributes or elements via the constructor

new XElement("Conn", new XAttribute("Server", comboBox1.Text), new XAttribute("Database", combobox2.Text));

or you can use the Add-Method of the XElement to add attributes

XElement element = new XElement("Conn");
XAttribute attribute = new XAttribute("Server", comboBox1.Text);

Spring MVC: How to return image in @ResponseBody?

In your application context declare a AnnotationMethodHandlerAdapter and registerByteArrayHttpMessageConverter:

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
  <property name="messageConverters">
      <bean id="byteArrayMessageConverter" class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>

also in the handler method set appropriate content type for your response.

SQL - How to find the highest number in a column?

You can do


Send form data with jquery ajax json

here is a simple one

here is my test.php for testing only


// this is just a test
//send back to the ajax request the request

echo json_encode($_POST);

here is my index.html

<!DOCTYPE html>



<form id="form" action="" method="post">
Name: <input type="text" name="name"><br>
Age: <input type="text" name="email"><br>
FavColor: <input type="text" name="favc"><br>
<input id="submit" type="button" name="submit" value="submit">

<script src=""></script>
        // click on button submit
        $("#submit").on('click', function(){
            // send ajax
                url: 'test.php', // url where to submit the request
                type : "POST", // type of action POST || GET
                dataType : 'json', // data type
                data : $("#form").serialize(), // post data || get data
                success : function(result) {
                    // you can see the result from the console
                    // tab of the developer tools
                error: function(xhr, resp, text) {
                    console.log(xhr, resp, text);


Both file are place in the same directory

Strip spaces/tabs/newlines - python

import re

mystr = "I want to Remove all white \t spaces, new lines \n and tabs \t"
print re.sub(r"\W", "", mystr)

Output : IwanttoRemoveallwhitespacesnewlinesandtabs

Simulate Keypress With jQuery

The keypress event from jQuery is meant to do this sort of work. You can trigger the event by passing a string "keypress" to .trigger(). However to be more specific you can actually pass a jQuery.Event object (specify the type as "keypress") as well and provide any properties you want such as the keycode being the spacebar.

Read the above documentation for more details.

HTML5 Canvas: Zooming

One option is to use css zoom feature:


:first-child not working as expected

:first-child selects the first h1 if and only if it is the first child of its parent element. In your example, the ul is the first child of the div.

The name of the pseudo-class is somewhat misleading, but it's explained pretty clearly here in the spec.

jQuery's :first selector gives you what you're looking for. You can do this:

$('.detail_container h1:first').css("color", "blue");

Where is svn.exe in my machine?

First off, if subversion installed on your machine? if not look at what server your tortoisesvn is setup to connect to.

the default location when subversion is installed is c:\program files\subversion you can find svn.exe in c:\program files\subversion\bin where you can run your cmd line actions.

Import CSV file as a pandas DataFrame

%cd C:\Users\asus\Desktop\python
import pandas as pd
df = pd.read_csv('value.txt')
    Date    price   factor_1    factor_2
0   2012-06-11  1600.20 1.255   1.548
1   2012-06-12  1610.02 1.258   1.554
2   2012-06-13  1618.07 1.249   1.552
3   2012-06-14  1624.40 1.253   1.556
4   2012-06-15  1626.15 1.258   1.552

C# : assign data to properties via constructor vs. instantiating

Second approach is object initializer in C#

Object initializers let you assign values to any accessible fields or properties of an object at creation time without having to explicitly invoke a constructor.

The first approach

var albumData = new Album("Albumius", "Artistus", 2013);

explicitly calls the constructor, whereas in second approach constructor call is implicit. With object initializer you can leave out some properties as well. Like:

 var albumData = new Album
            Name = "Albumius",

Object initializer would translate into something like:

var albumData; 
var temp = new Album();
temp.Name = "Albumius";
temp.Artist = "Artistus";
temp.Year = 2013;
albumData = temp;

Why it uses a temporary object (in debug mode) is answered here by Jon Skeet.

As far as advantages for both approaches are concerned, IMO, object initializer would be easier to use specially if you don't want to initialize all the fields. As far as performance difference is concerned, I don't think there would any since object initializer calls the parameter less constructor and then assign the properties. Even if there is going to be performance difference it should be negligible.

Generate sha256 with OpenSSL and C++

Here's the function I personally use - I simply derived it from the function I used for sha-1 hashing:

char *str2sha256( const char *str, int length ) {
  int n;
  SHA256_CTX c;
  unsigned char digest[ SHA256_DIGEST_LENGTH ];
  char *out = (char*) malloc( 33 );

  SHA256_Init( &c );

  while ( length > 0 ) {
    if ( length > 512 ) SHA256_Update( &c, str, 512 );
    else SHA256_Update( &c, str, length );

    length -= 512;
    str += 512;

  SHA256_Final ( digest, &c );

  for ( n = 0; n < SHA256_DIGEST_LENGTH; ++n )
    snprintf( &( out[ n*2 ] ), 16*2, "%02x", (unsigned int) digest[ n ] );

  return out;

Python creating a dictionary of lists

Your question has already been answered, but IIRC you can replace lines like:

if d.has_key(scope_item):


if scope_item in d:

That is, d references d.keys() in that construction. Sometimes defaultdict isn't the best option (for example, if you want to execute multiple lines of code after the else associated with the above if), and I find the in syntax easier to read.

Installing a local module using npm?

Since asked and answered by the same person, I'll add a npm link as an alternative.

from docs:

This is handy for installing your own stuff, so that you can work on it and test it iteratively without having to continually rebuild.

cd ~/projects/node-bloggy  # go into the dir of your main project
npm link ../node-redis     # link the dir of your dependency

[Edit] As of NPM 2.0, you can declare local dependencies in package.json

"dependencies": {
    "bar": "file:../foo/bar"

Where can I find my Facebook application id and secret key?

Peter's post is pretty much spot on, but if you want to learn how to navigate to it yourself here are the instructions:

On the left hand menu, you need to click "more", then you'll see "Developer", click on it. Afterwards you'll be presented with a page where your apps are listed under "My Applications" click on "See my applications". You can find all your API Key, secrets, and IDs there.

Creating a DateTime in a specific Time Zone in c#

The other answers here are useful but they don't cover how to access Pacific specifically - here you go:

public static DateTime GmtToPacific(DateTime dateTime)
    return TimeZoneInfo.ConvertTimeFromUtc(dateTime,
        TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time"));

Oddly enough, although "Pacific Standard Time" normally means something different from "Pacific Daylight Time," in this case it refers to Pacific time in general. In fact, if you use FindSystemTimeZoneById to fetch it, one of the properties available is a bool telling you whether that timezone is currently in daylight savings or not.

You can see more generalized examples of this in a library I ended up throwing together to deal with DateTimes I need in different TimeZones based on where the user is asking from, etc:

This won't work outside of Windows (for example Mono on Linux) since the list of times comes from the Windows Registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\

Underneath that you'll find keys (folder icons in Registry Editor); the names of those keys are what you pass to FindSystemTimeZoneById. On Linux you have to use a separate Linux-standard set of timezone definitions, which I've not adequately explored.

Java: String - add character n-times

In case of Java 8 you can do:

int n = 4;
String existing = "...";
String result = existing + String.join("", Collections.nCopies(n, "*"));



In Java 8 the String.join method was added. But Collections.nCopies is even in Java 5.

How do I check if a cookie exists?

This is an old question, but here's the approach I use ...

function getCookie(name) {
    var match = document.cookie.match(RegExp('(?:^|;\\s*)' + name + '=([^;]*)')); 
    return match ? match[1] : null;

This returns null either when the cookie doesn't exist, or when it doesn't contain the requested name.
Otherwise, the value (of the requested name) is returned.

A cookie should never exist without a value -- because, in all fairness, what's the point of that?
If it's no longer needed, it's best to just get rid of it all together.

function deleteCookie(name) {
    document.cookie = name +"=; Path=/; Expires=Thu, 01 Jan 1970 00:00:01 GMT;";

REST API - Bulk Create or Update in single request

In a project I worked at we solved this problem by implement something we called 'Batch' requests. We defined a path /batch where we accepted json in the following format:

      path: '/docs',
      method: 'post',
      body: {
         doc_number: 1,
         binder: 1
      path: '/docs',
      method: 'post',
      body: {
         doc_number: 5,
         binder: 8
      path: '/docs',
      method: 'post',
      body: {
         doc_number: 6,
         binder: 3

The response have the status code 207 (Multi-Status) and looks like this:

      path: '/docs',
      method: 'post',
      body: {
         doc_number: 1,
         binder: 1
      status: 200
      path: '/docs',
      method: 'post',
      body: {
         error: {
            msg: 'A document with doc_number 5 already exists'
      status: 409
      path: '/docs',
      method: 'post',
      body: {
         doc_number: 6,
         binder: 3
      status: 200

You could also add support for headers in this structure. We implemented something that proved useful which was variables to use between requests in a batch, meaning we can use the response from one request as input to another.

Facebook and Google have similar implementations:

When you want to create or update a resource with the same call I would use either POST or PUT depending on the case. If the document already exist, do you want the entire document to be:

  1. Replaced by the document you send in (i.e. missing properties in request will be removed and already existing overwritten)?
  2. Merged with the document you send in (i.e. missing properties in request will not be removed and already existing properties will be overwritten)?

In case you want the behavior from alternative 1 you should use a POST and in case you want the behavior from alternative 2 you should use PUT.

As people already suggested you could also go for PATCH, but I prefer to keep API's simple and not use extra verbs if they are not needed.

Error in <my code> : object of type 'closure' is not subsettable

You don't define the vector, url, before trying to subset it. url is also a function in the base package, so url[i] is attempting to subset that function... which doesn't make sense.

You probably defined url in your prior R session, but forgot to copy that code to your script.

What is the difference between ports 465 and 587?

587 vs. 465

These port assignments are specified by the Internet Assigned Numbers Authority (IANA):

  • Port 587: [SMTP] Message submission (SMTP-MSA), a service that accepts submission of email from email clients (MUAs). Described in RFC 6409.
  • Port 465: URL Rendezvous Directory for SSM (entirely unrelated to email)

Historically, port 465 was initially planned for the SMTPS encryption and authentication “wrapper” over SMTP, but it was quickly deprecated (within months, and over 15 years ago) in favor of STARTTLS over SMTP (RFC 3207). Despite that fact, there are probably many servers that support the deprecated protocol wrapper, primarily to support older clients that implemented SMTPS. Unless you need to support such older clients, SMTPS and its use on port 465 should remain nothing more than an historical footnote.

The hopelessly confusing and imprecise term, SSL, has often been used to indicate the SMTPS wrapper and TLS to indicate the STARTTLS protocol extension.

For completeness: Port 25

  • Port 25: Simple Mail Transfer (SMTP-MTA), a service that accepts submission of email from other servers (MTAs or MSAs). Described in RFC 5321.


mailto link multiple body lines

You can use URL encoding to encode the newline as %0A.

mailto:emai[email protected]?subject=test&body=type%20your%0Amessage%20here

While the above appears to work in many cases, user olibre points out that the RFC governing the mailto URI scheme specifies that %0D%0A (carriage return + line feed) should be used instead of %0A (line feed). See also: Newline Representations.

TypeError: 'builtin_function_or_method' object is not subscriptable

Can't believe this thread was going on for so long. You would get this error if you got distracted and used [] instead of (), at least my case.

Pop is a method on the list data type,

Therefore, you shouldn't be using pop as if it was a list itself, pop[0]. It's a method that takes an optional parameter representing an index, so as Tushar Palawat pointed out in one of the answers that didn't get approved, the correct adjustment which will fix the example above is:


If you don't believe, run a sample such as:

if __name__ == '__main__':
  listb = ["-test"]
  if( listb[0] == "-test"):

Other adjustments would work as well, but it feels as they are abusing the Python language. This thread needs to get fixed, not to confuse users.

Addition, a.pop() removes and returns the last item in the list. As a result, a.pop()[0] will get the first character of that last element. It doesn't seem that is what the given code snippet is aiming to achieve.

How to Deep clone in javascript

Very simple way, maybe too simple:

var cloned = JSON.parse(JSON.stringify(objectToClone));

Is it possible to use Java 8 for Android development?

Easy way

You can enable java 1.8 support for android project.

  • Open Project Structure

    • Either by pressing Ctrl + Shift + Alt + S

    • Or File > Project Structure

  • Update the Source Compatibility and Target Compatibility to 1.8 in the Project Structure dialog as shown (click File > Project Structure).


Or you can use gradle

 android {
   compileOptions {
       sourceCompatibility JavaVersion.VERSION_1_8
       targetCompatibility JavaVersion.VERSION_1_8

Sync project. And that's it!

Note: Java 1.8 support can be enabled for Android Studio 3.0.0 or higher. See Documentation for further reading.

How to write UPDATE SQL with Table alias in SQL Server 2008?

The syntax for using an alias in an update statement on SQL Server is as follows:

WHERE Q.ID = 101;

The alias should not be necessary here though.

Reset the Value of a Select Box

The easiest method without using javaScript is to put all your <select> dropdown inside a <form> tag and use form reset button. Example:

    <option selected>three</option>
  <input type="reset" value="Reset" />

Or, using JavaScript, it can be done in following way:

HTML Code:

  <option selected>one</option>
<button id="revert">Reset</button>

And JavaScript code:

const button = document.getElementById("revert");
const options = document.querySelectorAll('select option');
button.onclick = () => {
  for (var i = 0; i < options.length; i++) {
    options[i].selected = options[i].defaultSelected;

Both of these methods will work if you have multiple selected items or single selected item.

.NET Console Application Exit Event

Here is a complete, very simple .Net solution that works in all versions of windows. Simply paste it into a new project, run it and try CTRL-C to view how it handles it:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;

namespace TestTrapCtrlC{
    public class Program{
        static bool exitSystem = false;

        #region Trap application termination
        private static extern bool SetConsoleCtrlHandler(EventHandler handler, bool add);

        private delegate bool EventHandler(CtrlType sig);
        static EventHandler _handler;

        enum CtrlType {
         CTRL_C_EVENT = 0,
         CTRL_BREAK_EVENT = 1,
         CTRL_CLOSE_EVENT = 2,
         CTRL_LOGOFF_EVENT = 5,

        private static bool Handler(CtrlType sig) {
            Console.WriteLine("Exiting system due to external CTRL-C, or process kill, or shutdown");

            //do your cleanup here
            Thread.Sleep(5000); //simulate some cleanup delay

            Console.WriteLine("Cleanup complete");

            //allow main to run off
             exitSystem = true;

            //shutdown right away so there are no lingering threads

            return true;

        static void Main(string[] args) {
            // Some biolerplate to react to close window event, CTRL-C, kill, etc
            _handler += new EventHandler(Handler);
            SetConsoleCtrlHandler(_handler, true);

            //start your multi threaded program here
            Program p = new Program();

            //hold the console so it doesn’t run off the end
            while(!exitSystem) {

        public void Start() {
            // start a thread and start doing some processing
            Console.WriteLine("Thread started, processing..");

CSS Selector for <input type="?"

Sadly the other posters are correct that you're ...actually as corrected by kRON, you are ok with your IE7 and a strict doc, but most of us with IE6 requirements are reduced to JS or class references for this, but it is a CSS2 property, just one without sufficient support from IE^h^h browsers.

Out of completeness, the type selector is - similar to xpath - of the form [attribute=value] but many interesting variants exist. It will be quite powerful when it's available, good thing to keep in your head for IE8.

How to set the image from drawable dynamically in android?

This works for me (dont use the extension of the image, just the name):

String imagename = "myImage";
int res = getResources().getIdentifier(imagename, "drawable", this.getPackageName());
imageview= (ImageView)findViewById(;

python: Change the scripts working directory to the script's own directory

This will change your current working directory to so that opening relative paths will work:

import os

However, you asked how to change into whatever directory your Python script is located, even if you don't know what directory that will be when you're writing your script. To do this, you can use the os.path functions:

import os

abspath = os.path.abspath(__file__)
dname = os.path.dirname(abspath)

This takes the filename of your script, converts it to an absolute path, then extracts the directory of that path, then changes into that directory.

How to pass variable number of arguments to printf/sprintf

I should have read more on existing questions in stack overflow.

C++ Passing Variable Number of Arguments is a similar question. Mike F has the following explanation:

There's no way of calling (eg) printf without knowing how many arguments you're passing to it, unless you want to get into naughty and non-portable tricks.

The generally used solution is to always provide an alternate form of vararg functions, so printf has vprintf which takes a va_list in place of the .... The ... versions are just wrappers around the va_list versions.

This is exactly what I was looking for. I performed a test implementation like this:

void Error(const char* format, ...)
    char dest[1024 * 16];
    va_list argptr;
    va_start(argptr, format);
    vsprintf(dest, format, argptr);

How can I get the Windows last reboot reason

This article explains in detail how to find the reason for last startup/shutdown. In my case, this was due to windows SCCM pushing updates even though I had it disabled locally. Visit the article for full details with pictures. For reference, here are the steps copy/pasted from the website:

  1. Press the Windows + R keys to open the Run dialog, type eventvwr.msc, and press Enter.

  2. If prompted by UAC, then click/tap on Yes (Windows 7/8) or Continue (Vista).

  3. In the left pane of Event Viewer, double click/tap on Windows Logs to expand it, click on System to select it, then right click on System, and click/tap on Filter Current Log.

  4. Do either step 5 or 6 below for what shutdown events you would like to see.

  5. To See the Dates and Times of All User Shut Downs of the Computer

    A) In Event sources, click/tap on the drop down arrow and check the USER32 box.

    B) In the All Event IDs field, type 1074, then click/tap on OK.

    C) This will give you a list of power off (shutdown) and restart Shutdown Type of events at the top of the middle pane in Event Viewer.

    D) You can scroll through these listed events to find the events with power off as the Shutdown Type. You will notice the date and time, and what user was responsible for shutting down the computer per power off event listed.

    E) Go to step 7.

  6. To See the Dates and Times of All Unexpected Shut Downs of the Computer

    A) In the All Event IDs field, type 6008, then click/tap on OK.

    B) This will give you a list of unexpected shutdown events at the top of the middle pane in Event Viewer. You can scroll through these listed events to see the date and time of each one.

How to Set Selected value in Multi-Value Select in Jquery-Select2.?

Use multiselect function as below.

$('#drp_Books_Ill_Illustrations').multiSelect('select', 'value');

What are the dark corners of Vim your mom never told you about?

^O and ^I

Go to older/newer position. When you are moving through the file (by searching, moving commands etc.) vim rember these "jumps", so you can repeat these jumps backward (^O - O for old) and forward (^I - just next to I on keyboard). I find it very useful when writing code and performing a lot of searches.


Go to position where Insert mode was stopped last. I find myself often editing and then searching for something. To return to editing place press gi.


put cursor on file name (e.g. include header file), press gf and the file is opened


similar to gf but recognizes format "[file name]:[line number]". Pressing gF will open [file name] and set cursor to [line number].

^P and ^N

Auto complete text while editing (^P - previous match and ^N next match)


While editing completes to the same line (useful for programming). You write code and then you recall that you have the same code somewhere in file. Just press ^X^L and the full line completed


Complete file names. You write "/etc/pass" Hmm. You forgot the file name. Just press ^X^F and the filename is completed

^Z or :sh

Move temporary to the shell. If you need a quick bashing:

  • press ^Z (to put vi in background) to return to original shell and press fg to return to vim back
  • press :sh to go to sub shell and press ^D/exit to return to vi back

How to set environment variable for everyone under my linux system?

If your LinuxOS has this file:


You can use it to permanently set environmental variables for all users.

Extracted from:

How to write :hover using inline style?

Not gonna happen with CSS only

Inline javascript

<a href='index.html' 
    Click Me

In a working draft of the CSS2 spec it was declared that you could use pseudo-classes inline like this:

<a href=""
   style="{color: blue; background: white}  /* a+=0 b+=0 c+=0 */
      :visited {color: green}           /* a+=0 b+=1 c+=0 */
      :hover {background: yellow}       /* a+=0 b+=1 c+=0 */
      :visited:hover {color: purple}    /* a+=0 b+=2 c+=0 */

but it was never implemented in the release of the spec as far as I know.

Checking out Git tag leads to "detached HEAD state"

Yes, it is normal. This is because you checkout a single commit, that doesnt have a head. Especially it is (sooner or later) not a head of any branch.

But there is usually no problem with that state. You may create a new branch from the tag, if this makes you feel safer :)

Redirecting to a page after submitting form in HTML

You need to use the jQuery AJAX or XMLHttpRequest() for post the data to the server. After data posting you can redirect your page to another page by window.location.href.


 var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
      window.location.href = '';
  };"POST", "demo_post.asp", true);

CodeIgniter: 404 Page Not Found on Live Server

I had the same problem. Changing controlers first letter to uppercase helped.

Create Excel file in Java

Fair warning about Apache POI's Excel generation... (I know this is an old post, but it's important in case someone looks this up again like I just did)

It had a memory leak issue, which supposedly was solved by 2006, but which people quite recently have still been experiencing. If you want to automate generating a large amount of excel (i.e., if you want to generate a single, large file, a large number of small files, or both), I'd recommend using a different API. Either that, or increasing the JVM stack size to preposterous proportions, and maybe looking into interning strings if you know you won't actually be working with many different strings (although, of course, interning strings means that if you have a large number of different strings, you'll have an entirely different program-crashing memory problem. So, consider that before you go that route).

What is an AssertionError? In which case should I throw it from my own code?

Of course the "You shall not instantiate an item of this class" statement has been violated, but if this is the logic behind that, then we should all throw AssertionErrors everywhere, and that is obviously not what happens.

The code isn't saying the user shouldn't call the zero-args constructor. The assertion is there to say that as far as the programmer is aware, he/she has made it impossible to call the zero-args constructor (in this case by making it private and not calling it from within Example's code). And so if a call occurs, that assertion has been violated, and so AssertionError is appropriate.

Resize background image in div using css


You have multiple options:

  1. background-size: 100% 100%; - image gets stretched (aspect ratio may be preserved, depending on browser)
  2. background-size: contain; - image is stretched without cutting it while preserving aspect ratio
  3. background-size: cover; - image is completely covering the element while preserving aspect ratio (image can be cut off)

/edit: And now, there is even more:

Demo on Codepen

Update 2017: Preview

Here are screenshots for some browsers to show their differences.


preview background types chrome


preview background types firefox


preview background types edge


preview background types ie11

Takeaway Message

background-size: 100% 100%; produces the least predictable result.


How can I check if the array of objects have duplicate property values?

//checking duplicate elements in an array
var arr=[1,3,4,6,8,9,1,3,4,7];
var hp=new Map();
var freq=0;
for(var i=1;i<arr.length;i++){
// console.log(arr[i-1]+" "+arr[i]);


How to check currently internet connection is available or not in android

Use ConnectivityManager Service

Source Link

public class Utils {

   static ConnectivityManager connectivityManager;

    public static String isOnline(Context context) {
        JSONArray array = new JSONArray();
        JSONObject jsonObject = new JSONObject();
        try {
        } catch (JSONException e) {
        try {
            connectivityManager = (ConnectivityManager) context

            NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
            Log.i("networkInfo", networkInfo.toString());
            jsonObject.put("connected",(networkInfo != null && networkInfo.isAvailable() &&
            return array.toString();

        } catch (Exception e) {
            System.out.println("CheckConnectivity Exception: " + e.getMessage());
            Log.v("connectivity", e.toString());
        return array.toString();


Using floats with sprintf() in embedded C

Look in the documentation for sprintf for your platform. Its usually %f or %e. The only place you will find a definite answer is the documentation... if its undocumented all you can do then is contact the supplier.

What platform is it? Someone might already know where the docs are... :)

Using node.js as a simple web server

The way I do it is to first of all install node static server globally via

npm install node-static -g

then navigate to the directory that contains your html files and start the static server with static.

Go to the browser and type localhost:8080/"yourHtmlFile".

How to simulate a click with JavaScript?

The top answer is the best! However, it was not triggering mouse events for me in Firefox when etype = 'click'.

So, I changed the document.createEvent to 'MouseEvents' and that fixed the problem. The extra code is to test whether or not another bit of code was interfering with the event, and if it was cancelled I would log that to console.

function eventFire(el, etype){
  if (el.fireEvent) {
    el.fireEvent('on' + etype);
  } else {
    var evObj = document.createEvent('MouseEvents');
    evObj.initEvent(etype, true, false);
    var canceled = !el.dispatchEvent(evObj);
    if (canceled) {
      // A handler called preventDefault.
      console.log("automatic click canceled");
    } else {
      // None of the handlers called preventDefault.

SVN Error: Commit blocked by pre-commit hook (exit code 1) with output: Error: n/a (6)

I got the error as, "svn: Commit blocked by pre-commit hook (exit code 1) with output: Failed with exception: Lost connection to MySQL server at 'reading initial communication packet', system error: 104."

I tried 'svn commit' after 'svn cleanup'. And It works fine!.

Create a string and append text to it

Another way to do this is to add the new characters to the string as follows:

Dim str As String

str = ""

To append text to your string this way:

str = str & "and this is more text"

Using Predicate in Swift

I think this would be a better way to do it in Swift:

func filterContentForSearchText(searchText:NSString, scope:NSString)
   searchResults = recipes.filter { name.rangeOfString(searchText) != nil  }

Program "make" not found in PATH

Are you trying to run "Hello world" for the first time? Please make sure you choose proper toolchain. For Windows you have to choose MinGW GCC. enter image description here

To make MinGW GCC compiler as default or change you original project with error "Program “make” not found in PATH" or "launch failed binary not found eclipse c++" when you trying to run program simply go to Windows >> Preferences >> C\C++ Build >> Tool Chain Editor >> Change Current toolchain to MinGW GCC

enter image description here

Filtering a list of strings based on contents

mylist = ['a', 'ab', 'abc']
assert 'ab' in mylist

How to Create a script via batch file that will uninstall a program if it was installed on windows 7 64-bit or 32-bit

wmic can call an uninstaller. I haven't tried this, but I think it might work.

wmic /node:computername /user:adminuser /password:password product where name="name of application" call uninstall

If you don't know exactly what the program calls itself, do

wmic product get name | sort

and look for it. You can also uninstall using SQL-ish wildcards.

wmic /node:computername /user:adminuser /password:password product where "name like '%j2se%'" call uninstall

... for example would perform a case-insensitive search for *j2se* and uninstall "J2SE Runtime Environment 5.0 Update 12". (Note that in the example above, %j2se% is not an environment variable, but simply the word "j2se" with a SQL-ish wildcard on each end. If your search string could conflict with an environment or script variable, use double percents to specify literal percent signs, like %%j2se%%.)

If wmic prompts for y/n confirmation before completing the uninstall, try this:

echo y | wmic /node:computername /user:adminuser /password:password product where name="whatever" call uninstall

... to pass a y to it before it even asks.

I haven't tested this, but it's worth a shot anyway. If it works on one computer, then you can just loop through a text file containing all the computer names within your organization using a for loop, or put it in a domain policy logon script.

How to update record using Entity Framework Core?

To update an entity with Entity Framework Core, this is the logical process:

  1. Create instance for DbContext class
  2. Retrieve entity by key
  3. Make changes on entity's properties
  4. Save changes

Update() method in DbContext:

Begins tracking the given entity in the Modified state such that it will be updated in the database when SaveChanges() is called.

Update method doesn't save changes in database; instead, it sets states for entries in DbContext instance.

So, We can invoke Update() method before to save changes in database.

I'll assume some object definitions to answer your question:

  1. Database name is Store

  2. Table name is Product

Product class definition:

public class Product
    public int? ProductID { get; set; }
    public string ProductName { get; set; }
    public string Description { get; set; }
    public decimal? UnitPrice { get; set; }

DbContext class definition:

public class StoreDbContext : DbContext
    public DbSet<Product> Products { get; set; }
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        optionsBuilder.UseSqlServer("Your Connection String");

    protected override void OnModelCreating(ModelBuilder modelBuilder)
        modelBuilder.Entity<Order>(entity =>
            // Set key for entity
            entity.HasKey(p => p.ProductID);

Logic to update entity:

using (var context = new StoreDbContext())
        // Retrieve entity by id
        // Answer for question #1
        var entity = context.Products.FirstOrDefault(item => item.ProductID == id);
        // Validate entity is not null
        if (entity != null)
            // Answer for question #2

            // Make changes on entity
            entity.UnitPrice = 49.99m;
            entity.Description = "Collector's edition";
            /* If the entry is being tracked, then invoking update API is not needed. 
              The API only needs to be invoked if the entry was not tracked. 
            // context.Products.Update(entity);
            // Save changes in database

What is difference between MVC, MVP & MVVM design pattern in terms of coding c#

Some basic differences can be written in short:


Traditional MVC is where there is a

  1. Model: Acts as the model for data
  2. View : Deals with the view to the user which can be the UI
  3. Controller: Controls the interaction between Model and View, where view calls the controller to update model. View can call multiple controllers if needed.


Similar to traditional MVC but Controller is replaced by Presenter. But the Presenter, unlike Controller is responsible for changing the view as well. The view usually does not call the presenter.


The difference here is the presence of View Model. It is kind of an implementation of Observer Design Pattern, where changes in the model are represented in the view as well, by the VM. Eg: If a slider is changed, not only the model is updated but the data which may be a text, that is displayed in the view is updated as well. So there is a two-way data binding.

Can I pass parameters in computed properties in Vue.Js

Most probably you want to use a method

<span>{{ fullName('Hi') }}</span>

methods: {
  fullName(salut) {
      return `${salut} ${this.firstName} ${this.lastName}`

Longer explanation

Technically you can use a computed property with a parameter like this:

computed: {
   fullName() {
      return salut => `${salut} ${this.firstName} ${this.lastName}`

(Thanks Unirgy for the base code for this.)

The difference between a computed property and a method is that computed properties are cached and change only when their dependencies change. A method will evaluate every time it's called.

If you need parameters, there are usually no benefits of using a computed property function over a method in such a case. Though it allows you to have a parametrized getter function bound to the Vue instance, you lose caching so not really any gain there, in fact, you may break reactivity (AFAIU). You can read more about this in Vue documentation

The only useful situation is when you have to use a getter and need to have it parametrized. For instance, this situation happens in Vuex. In Vuex it's the only way to synchronously get parametrized result from the store (actions are async). Thus this approach is listed by official Vuex documentation for its getters

Escape double quote in VB string

Another example:

Dim myPath As String = """" & Path.Combine(part1, part2) & """"

Good luck!

Android Webview - Completely Clear the Cache


Did the trick

How to order citations by appearance using BibTeX?

There are three good answers to this question.

  • Use the unsrt bibliography style, if you're happy with its formatting otherwise
  • Use the makebst (link) tool to design your own bibliography style

And my personal recommendation:

  • Use the biblatex package (link). It's the most complete and flexible bibliography tool in the LaTeX world.

Using biblatex, you'd write something like

\bibliography{journals,phd-references} % Where journals.bib and phd-references.bib are BibTeX databases

Javascript: getFullyear() is not a function

Try this...

 var start = new Date(document.getElementById('Stardate').value);
 var y = start.getFullYear();

Is there a limit to the length of a GET request?

This article sums it up pretty well

Summary: It's implementation dependent, as there is no specified limit in the RFC. It'd be safe to use up to 2000 characters (IE's limit.) If you are anywhere near this length, you should make sure you really need URIs that long, maybe an alternative design could get around that.

URIs should be readable, even when used to send data.

How to turn off caching on Firefox?

The Web Developer Toolbar has an option to disable caching which makes it very easy to turn it on and off when you need it.

The type initializer for 'CrystalDecisions.CrystalReports.Engine.ReportDocument' threw an exception

As "M.A. Hanin" said above, it can caused by an InnerException like this:

"Unrecognized configuration section userSettings. (C:\Users\Pourakbar.h\AppData\Local\Accounting\Accounting.vshost.exe_Url_a4h1gnabohiu4wgiejk0d21rc2kbwr4g\\user.config line 3)"

and I deleted the folder: C:\Users\Pourakbar.h\AppData\Local\Accounting\Accounting.vshost.exe_Url_a4h1gnabohiu4wgiejk0d21rc2kbwr4g from my computer and that worked for me!

How to list files using dos commands?

Try dir /b, for bare format.

dir /? will show you documentation of what you can do with the dir command. Here is the output from my Windows 7 machine:

C:\>dir /?
Displays a list of files and subdirectories in a directory.

DIR [drive:][path][filename] [/A[[:]attributes]] [/B] [/C] [/D] [/L] [/N]
  [/O[[:]sortorder]] [/P] [/Q] [/R] [/S] [/T[[:]timefield]] [/W] [/X] [/4]

              Specifies drive, directory, and/or files to list.

  /A          Displays files with specified attributes.
  attributes   D  Directories                R  Read-only files
               H  Hidden files               A  Files ready for archiving
               S  System files               I  Not content indexed files
               L  Reparse Points             -  Prefix meaning not
  /B          Uses bare format (no heading information or summary).
  /C          Display the thousand separator in file sizes.  This is the
              default.  Use /-C to disable display of separator.
  /D          Same as wide but files are list sorted by column.
  /L          Uses lowercase.
  /N          New long list format where filenames are on the far right.
  /O          List by files in sorted order.
  sortorder    N  By name (alphabetic)       S  By size (smallest first)
               E  By extension (alphabetic)  D  By date/time (oldest first)
               G  Group directories first    -  Prefix to reverse order
  /P          Pauses after each screenful of information.
  /Q          Display the owner of the file.
  /R          Display alternate data streams of the file.
  /S          Displays files in specified directory and all subdirectories.
  /T          Controls which time field displayed or used for sorting
  timefield   C  Creation
              A  Last Access
              W  Last Written
  /W          Uses wide list format.
  /X          This displays the short names generated for non-8dot3 file
              names.  The format is that of /N with the short name inserted
              before the long name. If no short name is present, blanks are
              displayed in its place.
  /4          Displays four-digit years

Switches may be preset in the DIRCMD environment variable.  Override
preset switches by prefixing any switch with - (hyphen)--for example, /-W.

Is it possible in Java to check if objects fields are null and then add default value to all those attributes?

I tried this and it works without any issues to validate if the field is empty. I have answered your question partially as I haven't personally tried to add default values to attributes

if(field.getText()!= null && !field.getText().isEmpty())

Hope it helps

Where does Android app package gets installed on phone

You will find the application folder at:

/data/data/"your package name"

you can access this folder using the DDMS for your Emulator. you can't access this location on a real device unless you have a rooted device.

Create normal zip file programmatically

You should look into Zip Packages

They are a more structured version of normal ZIP archives, requiring some meta stuff in the root. So other ZIP tools can open a package, but the Sysytem.IO.Packaging API can not open all ZIP files.

Android transparent status bar and actionbar

Just add these lines of code to your activity/fragment java file:


What's the difference between text/xml vs application/xml for webservice response

From the RFC (3023), under section 3, XML Media Types:

If an XML document -- that is, the unprocessed, source XML document -- is readable by casual users, text/xml is preferable to application/xml. MIME user agents (and web user agents) that do not have explicit support for text/xml will treat it as text/plain, for example, by displaying the XML MIME entity as plain text. Application/xml is preferable when the XML MIME entity is unreadable by casual users.

(emphasis mine)

How do I run a command on an already existing Docker container?

If you are trying to run shell script, you need run it as bash.

docker exec -it containerid bash -c /path/to/your/

How to make an HTTP POST web request

Yet another way of doing it:

using (HttpClient httpClient = new HttpClient())
using (MultipartFormDataContent form = new MultipartFormDataContent())
    form.Add(new StringContent(param1), "param1");
    form.Add(new StringContent(param2), "param2");
    using (HttpResponseMessage response = await httpClient.PostAsync(url, form))
        string res = await response.Content.ReadAsStringAsync();
        return res;

This way you can easily post a stream.

Matlab: Running an m-file from command-line

cat 1.m | matlab -nodesktop -nosplash

And I use Ubuntu

Hiding the address bar of a browser (popup)

It's different in every browser.

Some years ago, what you tried, was right. But nowadays it is regarded as a security risk by browser vendors that one cannot see the browsers address bar (for phishing reasons) and so they (or most of them) made the decision to always show the browser address bar. Which is good in my eyes.

Difference between JSONObject and JSONArray

To understand it in a easier way, following are the diffrences between JSON object and JSON array:

Link to Tabular Difference :

JSON Array

1. Arrays in JSON are used to organize a collection of related items
   (Which could be JSON objects)
2.  Array values must be of type string, number, object, array, boolean or null
3.  Syntax: 
           [ "Ford", "BMW", "Fiat" ]
4.  JSON arrays are surrounded by square brackets []. 
    **Tip to remember**  :  Here, order of element is important. That means you have 
    to go straight like the shape of the bracket i.e. straight lines. 
   (Note :It is just my logic to remember the shape of both.) 
5.  Order of elements is important. Example:  ["Ford","BMW","Fiat"] is not 
    equal to ["Fiat","BMW","Ford"]
6.  JSON can store nested Arrays that are passed as a value.

JSON Object

1.  JSON objects are written in key/value pairs.
2.  Keys must be strings, and values must be a valid JSON data type (string, number, 
    object, array, boolean or null).Keys and values are separated by a colon.
    Each key/value pair is separated by a comma.
3.  Syntax:
         { "name":"Somya", "age":25, "car":null }
4.  JSON objects are surrounded by curly braces {} 
    Tip to remember : Here, order of element is not important. That means you can go 
    the way you like. Therefore the shape of the braces i.e. wavy. 
    (Note : It is just my logic to remember the shape of both.)
5.  Order of elements is not important. 
    Example:  { rollno: 1, firstname: 'Somya'} 
                   is equal to 
             { firstname: 'Somya', rollno: 1}
6.  JSON can store nested objects in JSON format in addition to nested arrays.

Turning error reporting off php

Tried this yet?

@ini_set('display_errors', 0);

List only stopped Docker containers

The typical command is:

docker container ls -f 'status=exited'

However, this will only list one of the possible non-running statuses. Here's a list of all possible statuses:

  • created
  • restarting
  • running
  • removing
  • paused
  • exited
  • dead

You can filter on multiple statuses by passing multiple filters on the status:

docker container ls -f 'status=exited' -f 'status=dead' -f 'status=created'

If you are integrating this with an automatic cleanup script, you can chain one command to another with some bash syntax, output just the container id's with -q, and you can also limit to just the containers that exited successfully with an exit code filter:

docker container rm $(docker container ls -q -f 'status=exited' -f 'exited=0')

For more details on filters you can use, see Docker's documentation: