Programs & Examples On #Mkv

This tag is for questions about playback of, creation of, and programmatic interaction with, Matroska multimedia Container (*.mkv,*.mka) files.

How to playback MKV video in web browser?

You can use this following code. work just on chrome browser.

 function failed(e) {_x000D_
   // video playback failed - show a message saying why_x000D_
   switch ( {_x000D_
       alert('You aborted the video playback.');_x000D_
       alert('A network error caused the video download to fail part-way.');_x000D_
       alert('The video playback was aborted due to a corruption problem or because the video used features your browser did not support.');_x000D_
       alert('The video could not be loaded, either because the server or network failed or because the format is not supported.');_x000D_
       alert('An unknown error occurred.');_x000D_
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">_x000D_
<html xmlns="" xml:lang="en" lang="en">_x000D_
 <meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />_x000D_
 <meta name="author" content="Amin Developer!" />_x000D_
 <title>Untitled 1</title>_x000D_
<p><video src="" type='video/x-matroska; codecs="theora, vorbis"' autoplay controls onerror="failed(event)" ></video></p>_x000D_
<p><a href="YOU mkv FILE LINK GOES HERE TO DOWNLOAD">Download the video file</a>.</p>_x000D_

jQuery send HTML data through POST

If you want to send an arbitrary amount of data to your server, POST is the only reliable method to do that. GET would also be possible but clients and servers allow just a limited URL length (something like 2048 characters).

Getting a list of associative array keys

I am currently using Rob de la Cruz's reply:


And in a file loaded early on I have some lines of code borrowed from elsewhere on the Internet which cover the case of old versions of script interpreters that do not have Object.keys built in.

if (!Object.keys) {
    Object.keys = function(object) {
        var keys = [];
        for (var o in object) {
            if (object.hasOwnProperty(o)) {
        return keys;

I think this is the best of both worlds for large projects: simple modern code and backwards compatible support for old versions of browsers, etc.

Effectively it puts JW's solution into the function when Rob de la Cruz's Object.keys(obj) is not natively available.

Simulating Slow Internet Connection

You can try Dummynet, it can simulates queue and bandwidth limitations, delays, packet losses, and multipath effects

Validate that end date is greater than start date with jQuery

Little late to the party but here is my part

Date.parse(fromDate) > Date.parse(toDate)

Here is the detail:

var from = $("#from").val();
var to = $("#to").val();

if(Date.parse(from) > Date.parse(to)){
   alert("Invalid Date Range");
   alert("Valid date Range");

setting JAVA_HOME & CLASSPATH in CentOS 6


  1. Click on the Terminal icon in the desktop panel to open a terminal window and access the command prompt.
  2. Type the command which java to find the path to the Java executable file.
  3. Type the command su - to become the root user.
  4. Type the command vi /root/.bash_profile to open the system bash_profile file in the Vi text editor. You can replace vi with your preferred text editor.
  5. Type export JAVA_HOME=/usr/local/java/ at the bottom of the file. Replace /usr/local/java with the location found in step two.
  6. Save and close the bash_profile file.
  7. Type the command exit to close the root session.
  8. Log out of the system and log back in.
  9. Type the command echo $JAVA_HOME to ensure that the path was set correctly.

set java_home in centos

Difference between a SOAP message and a WSDL?

We can consider a telephone call In that Number is wsdl and exchange of information is soap.

WSDL is description how to connect with communication server.SOAP is have communication messages.

How can I define colors as variables in CSS?

Do not use css3 variables due to support.

I would do the following if you want a pure css solution.

  1. Use color classes with semenatic names.

    .bg-primary   { background: #880000; }
    .bg-secondary { background: #008800; }
    .bg-accent    { background: #F5F5F5; }
  2. Separate the structure from the skin (OOCSS)

    /* Instead of */
    h1 { 
        font-size: 2rem;
        line-height: 1.5rem;
        color: #8000;
    /* use this */
    h1 { 
        font-size: 2rem;
        line-height: 1.5rem;
    .bg-primary {
        background: #880000;
    /* This will allow you to reuse colors in your design */
  3. Put these inside a separate css file to change as needed.

Convert String to Integer in XSLT 1.0

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


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

Sorting Python list based on the length of the string

The same as in Eli's answer - just using a shorter form, because you can skip a lambda part here.

Creating new list:

>>> xs = ['dddd','a','bb','ccc']
>>> sorted(xs, key=len)
['a', 'bb', 'ccc', 'dddd']

In-place sorting:

>>> xs.sort(key=len)
>>> xs
['a', 'bb', 'ccc', 'dddd']

Converting a generic list to a CSV string

CsvHelper library is very popular in the Nuget.You worth it,man!

Using CsvHelper is really easy. It's default settings are setup for the most common scenarios.

Here is a little setup data.



Actor.cs (custom class object that represents an actor):

public class Actor
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }

Reading the CSV file using CsvReader:

var csv = new CsvReader( new StreamReader( "Actors.csv" ) );

var actorsList = csv.GetRecords();

Writing to a CSV file.

using (var csv = new CsvWriter( new StreamWriter( "Actors.csv" ) )) 
    csv.WriteRecords( actorsList );

Show div #id on click with jQuery

The problem you're having is that the event-handlers are being bound before the elements are present in the DOM, if you wrap the jQuery inside of a $(document).ready() then it should work perfectly well:

        $("#music").click(function () {


An alternative is to place the <script></script> at the foot of the page, so it's encountered after the DOM has been loaded and ready.

To make the div hide again, once the #music element is clicked, simply use toggle():

        $("#music").click(function () {

JS Fiddle demo.

And for fading:

        $("#music").click(function () {

JS Fiddle demo.

How to remove multiple indexes from a list at the same time?

Old question, but I have an answer.

First, peruse the elements of the list like so:

for x in range(len(yourlist)):
    print '%s: %s' % (x, yourlist[x])

Then, call this function with a list of the indexes of elements you want to pop. It's robust enough that the order of the list doesn't matter.

def multipop(yourlist, itemstopop):
    result = []
    itemstopop = itemstopop[::-1]
    for x in itemstopop:
    return result

As a bonus, result should only contain elements you wanted to remove.

In [73]: mylist = ['a','b','c','d','charles']

In [76]: for x in range(len(mylist)):



0: a

1: b

2: c

3: d

4: charles


In [77]: multipop(mylist, [0, 2, 4])

Out[77]: ['charles', 'c', 'a']


In [78]: mylist

Out[78]: ['b', 'd']

Why is not Element in Typescript?

I'm usually facing this problem when dealing with events from an input field, like key up. But remember that the event could stem from anywhere, e.g. from a keyup listener on document, where there is no associated value. So in order to correctly provide the information I'd provide an additional type:

interface KeyboardEventOnInputField extends KeyboardEvent {
  target: HTMLInputElement;

  onKeyUp(e: KeyboardEventOnInputField) {
    const inputValue =;

If the input to the function has a type of Event, you might need to tell typescript what it actually is:

  onKeyUp(e: Event) {
    const evt = e as KeyboardEventOnInputField;
    const inputValue =;;

This is for example required in Angular.

PL/SQL, how to escape single quote in a string?

In addition to DCookie's answer above, you can also use chr(39) for a single quote.

I find this particularly useful when I have to create a number of insert/update statements based on a large amount of existing data.

Here's a very quick example:

Lets say we have a very simple table, Customers, that has 2 columns, FirstName and LastName. We need to move the data into Customers2, so we need to generate a bunch of INSERT statements.

Select 'INSERT INTO Customers2 (FirstName, LastName) ' ||
       'VALUES (' || chr(39) || FirstName || chr(39) ',' || 
       chr(39) || LastName || chr(39) || ');' From Customers;

I've found this to be very useful when moving data from one environment to another, or when rebuilding an environment quickly.

What are my options for storing data when using React Native? (iOS and Android)

you can use Realm or Sqlite if you want to manage complex data type.

Otherwise go with inbuilt react native asynstorage

Insert current date/time using now() in a field using MySQL/PHP

These both work fine for me...

  $db = mysql_connect('localhost','user','pass');

  $stmt = "INSERT INTO `test` (`first`,`last`,`whenadded`) VALUES ".
  $rslt = mysql_query($stmt);

  $stmt = "INSERT INTO `users` (`first`,`last`,`whenadded`) VALUES ".
          "('{$first}', '{$last}', CURRENT_TIMESTAMP)";
  $rslt = mysql_query($stmt);


Side note: mysql_query() is not the best way to connect to MySQL in current versions of PHP.

Console.log not working at all

Consider a more pragmatic approach to the question of "doing it correctly".

console.log("about to bind scroll fx");

$(window).scroll(function() {

       console.log("scroll bound, loop through div's");


If both of those logs output correctly, then its likely the problem exists in your var declaration. To debug that, consider breaking it out into several lines:

var id='#'+$(this).attr('id');


var off=$(id).offset().top;
var hei=$(id).height();
var winscroll=$(window).scrollTop();
var dif=hei+off-($(window).height());

By doing this, at least during debugging, you may find that the var id is undefined, causing errors throughout the rest of the code. Is it possible some of your div tags do not have id's?

How to use regex in XPath "contains" function

If you're using Selenium with Firefox you should be able to use EXSLT extensions, and regexp:test()

Does this work for you?

String expr = "//*[regexp:test(@id, 'sometext[0-9]+_text')]";

Write in body request with HttpClient

If your xml is written by java.lang.String you can just using HttpClient in this way

    public void post() throws Exception{
        HttpClient client = new DefaultHttpClient();
        HttpPost post = new HttpPost("");
        String xml = "<xml>xxxx</xml>";
        HttpEntity entity = new ByteArrayEntity(xml.getBytes("UTF-8"));
        HttpResponse response = client.execute(post);
        String result = EntityUtils.toString(response.getEntity());

pay attention to the Exceptions.

BTW, the example is written by the httpclient version 4.x

How to Turn Off Showing Whitespace Characters in Visual Studio IDE

If the Toggle Visual Space icon shall be added to a Visual Studio toolbar of your choice, because it shall be turned on and off via mouse click, then follow this instruction:

  1. Customize the desired toolbar

  2. Click on Customize...

  3. Click on Add Command...

  4. Go to Edit and chose Toggle Visual Space

  5. Click on OK

Tested with Visual Studio 2019.

What is the difference between Swing and AWT?

The base difference that which already everyone mentioned is that one is heavy weight and other is light weight. Let me explain, basically what the term heavy weight means is that when you're using the awt components the native code used for getting the view component is generated by the Operating System, thats why it the look and feel changes from OS to OS. Where as in swing components its the responsibility of JVM to generate the view for the components. Another statement which i saw is that swing is MVC based and awt is not.

How do I disable a jquery-ui draggable?

Seems like no one looked at the original documentation. May be there was no it at that time))

Initialize a draggable with the disabled option specified.

$( ".selector" ).draggable({ disabled: true });

Get or set the disabled option, after init.

var disabled = $( ".selector" ).draggable( "option", "disabled" );
$( ".selector" ).draggable( "option", "disabled", true );

Spring boot: Unable to start embedded Tomcat servlet container

Try to change the port number in application.yaml (or to something else.

Compile/run assembler in Linux?

There is also FASM for Linux.

format ELF executable

segment readable executable

mov eax, 4
mov ebx, 1
mov ecx, hello_msg
mov edx, hello_size
int 80h

mov eax, 1
mov ebx, 0
int 80h

segment readable writeable

hello_msg db "Hello World!",10,0
hello_size = $-hello_msg

It comiles with

fasm hello.asm hello

Matching a space in regex

In Perl the switch is \s (whitespace).

Accessing member of base class

You are incorrectly using the super and this keyword. Here is an example of how they work:

class Animal {
    public name: string;
    constructor(name: string) { = name;
    move(meters: number) {
        console.log( + " moved " + meters + "m.");

class Horse extends Animal {
    move() {
        console.log( + " is Galloping...");
        console.log( + " is Galloping...");

var tom: Animal = new Horse("Tommy the Palomino"); = 'horseee'; 

// Outputs:

// horseee is Galloping...
// Tommy the Palomino is Galloping...
// Tommy the Palomino moved 45m.


  1. The first log outputs, this refers to the prototype chain of the object tom, not the object tom self. Because we have added a name property on the Animal.prototype, horseee will be outputted.
  2. The second log outputs, the this keyword refers to the the tom object itself.
  3. The third log is logged using the move method of the Animal base class. This method is called from Horse class move method with the syntax super.move(45);. Using the super keyword in this context will look for a move method on the prototype chain which is found on the Animal prototype.

Remember TS still uses prototypes under the hood and the class and extends keywords are just syntactic sugar over prototypical inheritance.

How does one set up the Visual Studio Code compiler/debugger to GCC?

You need to install C compiler, C/C++ extension, configure launch.json and tasks.json to be able to debug C code.

This article would guide you how to do it:

Will Google Android ever support .NET?

You're more likely to see an Android implementation of Silverlight. Microsoft rep has confirmed that it's possible, vs. the iPhone where the rep said it was problematic.

But a version of the .Net framework is possible. Just need someone to care about it that much :)

But really, moving from C# to Java isn't that big of a deal and considering the drastic differences between the two platforms (PC vs. G1) it seems unlikely that you'd be able to get by with one codebase for any app that you wanted to run on both.

Passing data between view controllers

The OP didn't mention view controllers but so many of the answers do, that I wanted to chime in with what some of the new features of the LLVM allow to make this easier when wanting to pass data from one view controller to another and then getting some results back.

Storyboard segues, ARC and LLVM blocks make this easier than ever for me. Some answers above mentioned storyboards and segues already but still relied on delegation. Defining delegates certainly works but some people may find it easier to pass pointers or code blocks.

With UINavigators and segues, there are easy ways of passing information to the subservient controller and getting the information back. ARC makes passing pointers to things derived from NSObjects simple so if you want the subservient controller to add/change/modify some data for you, pass it a pointer to a mutable instance. Blocks make passing actions easy so if you want the subservient controller to invoke an action on your higher level controller, pass it a block. You define the block to accept any number of arguments that makes sense to you. You can also design the API to use multiple blocks if that suits things better.

Here are two trivial examples of the segue glue. The first is straightforward showing one parameter passed for input, the second for output.

// Prepare the destination view controller by passing it the input we want it to work on
// and the results we will look at when the user has navigated back to this controller's view.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
    [[segue destinationViewController]

     // This parameter gives the next controller the data it works on.

     // This parameter allows the next controller to pass back results
     // by virtue of both controllers having a pointer to the same object.

This second example shows passing a callback block for the second argument. I like using blocks because it keeps the relevant details close together in the source - the higher level source.

// Prepare the destination view controller by passing it the input we want it to work on
// and the callback when it has done its work.

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
    [[segue destinationViewController]

     // This parameter gives the next controller the data it works on.

     // This parameter allows the next controller to pass back results.
     resultsBlock:^(id results) {
         // This callback could be as involved as you like.
         // It can use Grand Central Dispatch to have work done on another thread for example.
        [self setResultsFromNextController:results];

How do I encode/decode HTML entities in Ruby?

If you don't want to add a new dependency just to do this (like HTMLEntities) and you're already using Hpricot, it can both escape and unescape for you. It handles much more than CGI:

Hpricot.uxs "foo&nbsp;b&auml;r"
=> "foo bär"

Why is the time complexity of both DFS and BFS O( V + E )

Your sum

v1 + (incident edges) + v2 + (incident edges) + .... + vn + (incident edges)

can be rewritten as

(v1 + v2 + ... + vn) + [(incident_edges v1) + (incident_edges v2) + ... + (incident_edges vn)]

and the first group is O(N) while the other is O(E). :connection timed out: connect?

Exception :

This means your request didn't getting response from server in stipulated time. And their are some reasons for this exception:

  • Too many requests overloading the server
  • Request packet loss because of wrong network configuration or line overload
  • Sometimes firewall consume request packet before sever getting
  • Also depends on thread connection pool configuration and current status of connection pool
  • Response packet lost during transition

How to determine tables size in Oracle

If you don't have DBA rights then you can use user_segments table:

select bytes/1024/1024 MB from user_segments where segment_name='Table_name'

How to store file name in database, with other info while uploading image to server using PHP?

Adding the following avoids problems with quotes in file names, e.g.

"freddy's pic.jpg"

which are acceptable on some operating systems.





Java: Check the date format of current string is according to required format or not

For your case, you may use regex:

boolean checkFormat;

if (input.matches("([0-9]{2})/([0-9]{2})/([0-9]{4})"))

For a larger scope or if you want a flexible solution, refer to MadProgrammer's answer.


Almost 5 years after posting this answer, I realize that this is a stupid way to validate a date format. But i'll just leave this here to tell people that using regex to validate a date is unacceptable

DB2 SQL error: SQLCODE: -206, SQLSTATE: 42703

That only means that an undefined column or parameter name was detected. The errror that DB2 gives should point what that may be:


Double check your table definition. Maybe you just missed adding something.

I also tried google-ing this problem and saw this:

Size of Matrix OpenCV

cv:Mat mat;
int rows = mat.rows;
int cols = mat.cols;

cv::Size s = mat.size();
rows = s.height;
cols = s.width;

Also note that stride >= cols; this means that actual size of the row can be greater than element size x cols. This is different from the issue of continuous Mat and is related to data alignment.

How to resolve the error "Unable to access jarfile ApacheJMeter.jar errorlevel=1" while initiating Jmeter?

navigate to the url>download, which is under binaries.

this error is occurring since Apache jmeter.jar is missing in bin folder

Android marshmallow request permission?

Try this

This is the simplest way to ask for permission in Marshmallow version.

 if (ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED&&ContextCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED)
        //TO do here if permission is granted by user
        //ask for permission if user didnot given
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
            requestPermissions(new String[]{Manifest.permission.CAMERA,Manifest.permission.ACCESS_FINE_LOCATION}, 0);

Note:- Don't forget to add this same permission in manifest file also

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

Second Method Code for checking the permission is granted or not?

ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE,Manifest.permission.CAMERA}, 1);

And override the method

public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {
            if (grantResults.length > 0 && grantResults[1] == PackageManager.PERMISSION_GRANTED) {
         //                    grantResult[0] means it will check for the first postion permission which is READ_EXTERNAL_STORAGE
        //                    grantResult[1] means it will check for the Second postion permission which is CAMERA
                Toast.makeText(this, "Permission Granted", Toast.LENGTH_SHORT).show();
                Toast.makeText(this, "Permission not Granted", Toast.LENGTH_SHORT).show();

Convert a List<T> into an ObservableCollection<T>

ObservableCollection < T > has a constructor overload which takes IEnumerable < T >

Example for a List of int:

ObservableCollection<int> myCollection = new ObservableCollection<int>(myList);

One more example for a List of ObjectA:

ObservableCollection<ObjectA> myCollection = new ObservableCollection<ObjectA>(myList as List<ObjectA>);

Table variable error: Must declare the scalar variable "@temp"

You've declared @TEMP but in your insert statement used @temp. Case sensitive variable names.

Change @temp to @TEMP

Logical operator in a handlebars.js {{#if}} conditional

Handlebars supports nested operations. This provides a lot of flexibility (and cleaner code) if we write our logic a little differently.

{{#if (or section1 section2)}}
.. content

In fact, we can add all sorts of logic:

{{#if (or 
        (eq section1 "foo")
        (ne section2 "bar"))}}
.. content

Just register these helpers:

    eq: (v1, v2) => v1 === v2,
    ne: (v1, v2) => v1 !== v2,
    lt: (v1, v2) => v1 < v2,
    gt: (v1, v2) => v1 > v2,
    lte: (v1, v2) => v1 <= v2,
    gte: (v1, v2) => v1 >= v2,
    and() {
        return, Boolean);
    or() {
        return, 0, -1).some(Boolean);

Pandas - Plotting a stacked Bar Chart

Are you getting errors, or just not sure where to start?

%pylab inline
import pandas as pd
import matplotlib.pyplot as plt

df2 = df.groupby(['Name', 'Abuse/NFF'])['Name'].count().unstack('Abuse/NFF').fillna(0)
df2[['abuse','nff']].plot(kind='bar', stacked=True)

stacked bar plot

How to change default text color using custom theme?

When you create an App, a file called styles.xml will be created in your res/values folder. If you change the styles, you can change the background, text color, etc for all your layouts. That way you don’t have to go into each individual layout and change the it manually.


<resources xmlns:android="">
<style name="Theme.AppBaseTheme" parent="@android:style/Theme.Light">
    <item name="android:editTextColor">#295055</item> 
    <item name="android:textColorPrimary">#295055</item>
    <item name="android:textColorSecondary">#295055</item>
    <item name="android:textColorTertiary">#295055</item>
    <item name="android:textColorPrimaryInverse">#295055</item>
    <item name="android:textColorSecondaryInverse">#295055</item>
    <item name="android:textColorTertiaryInverse">#295055</item>

     <item name="android:windowBackground">@drawable/custom_background</item>        

<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">
    <!-- All customizations that are NOT specific to a particular API-level can go here. -->

parent="@android:style/Theme.Light" is Google’s native colors. Here is a reference of what the native styles are:

The default Android style is also called “Theme”. So you calling it Theme probably confused the program.

name="Theme.AppBaseTheme" means that you are creating a style that inherits all the styles from parent="@android:style/Theme.Light". This part you can ignore unless you want to inherit from AppBaseTheme again. = <style name="AppTheme" parent="AppBaseTheme">

@drawable/custom_background is a custom image I put in the drawable’s folder. It is a 300x300 png image.

#295055 is a dark blue color.

My code changes the background and text color. For Button text, please look through Google’s native stlyes (the link I gave u above).

Then in Android Manifest, remember to include the code:


How to set the locale inside a Debian/Ubuntu Docker container?

Put in your Dockerfile something adapted from

# Set the locale
RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && \
ENV LC_ALL en_US.UTF-8     

If you run Debian or Ubuntu, you also need to install locales to have locale-gen with

apt-get -y install locales

this is extracted from the very good post on that subject, from

Create session factory in Hibernate 4

Even there is an update in 4.3.0 API. ServiceRegistryBuilder is also deprecated in 4.3.0 and replaced with the StandardServiceRegistryBuilder. Now the actual code for creating the session factory would look this example on creating session factory.

What is a race condition?

Microsoft actually have published a really detailed article on this matter of race conditions and deadlocks. The most summarized abstract from it would be the title paragraph:

A race condition occurs when two threads access a shared variable at the same time. The first thread reads the variable, and the second thread reads the same value from the variable. Then the first thread and second thread perform their operations on the value, and they race to see which thread can write the value last to the shared variable. The value of the thread that writes its value last is preserved, because the thread is writing over the value that the previous thread wrote.

Entity framework code-first null foreign key

I have the same problem now , I have foreign key and i need put it as nullable, to solve this problem you should put

        .HasMany(c => c.Users)
        .WithOptional(c => c.Country)
        .HasForeignKey(c => c.CountryId)

in DBContext class I am sorry for answer you very late :)

How to print a dictionary line by line in Python?

Check the following one-liner:

print('\n'.join("%s\n%s" % (key1,('\n'.join("%s : %r" % (key2,val2) for (key2,val2) in val1.items()))) for (key1,val1) in cars.items()))


speed : 70
color : 2
speed : 60
color : 3

Generating Random Passwords

public static string GeneratePassword(int passLength) {
        var chars = "abcdefghijklmnopqrstuvwxyz@#$&ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        var random = new Random();
        var result = new string(
            Enumerable.Repeat(chars, passLength)
                      .Select(s => s[random.Next(s.Length)])
        return result;

Installing a specific version of angular with angular cli

Yes, it's possible to install a specific version of Angular using npm:

npm install -g @angular/[email protected]

Next, you need to use the ng new command to create an Angular project based on the specific version you used when installing the CLI:

ng new your-project-name

This will generate a project based on Angular v8.3.19, the version which was specified when installing Angular CLI.

What is logits, softmax and softmax_cross_entropy_with_logits?

Tensorflow 2.0 Compatible Answer: The explanations of dga and stackoverflowuser2010 are very detailed about Logits and the related Functions.

All those functions, when used in Tensorflow 1.x will work fine, but if you migrate your code from 1.x (1.14, 1.15, etc) to 2.x (2.0, 2.1, etc..), using those functions result in error.

Hence, specifying the 2.0 Compatible Calls for all the functions, we discussed above, if we migrate from 1.x to 2.x, for the benefit of the community.

Functions in 1.x:

  1. tf.nn.softmax
  2. tf.nn.softmax_cross_entropy_with_logits
  3. tf.nn.sparse_softmax_cross_entropy_with_logits

Respective Functions when Migrated from 1.x to 2.x:

  1. tf.compat.v2.nn.softmax
  2. tf.compat.v2.nn.softmax_cross_entropy_with_logits
  3. tf.compat.v2.nn.sparse_softmax_cross_entropy_with_logits

For more information about migration from 1.x to 2.x, please refer this Migration Guide.

'System.Net.Http.HttpContent' does not contain a definition for 'ReadAsAsync' and no extension method

Make sure that you have installed the correct NuGet package in your console application:

<package id="Microsoft.AspNet.WebApi.Client" version="4.0.20710.0" />

and that you are targeting at least .NET 4.0.

This being said, your GetAllFoos function is defined to return an IEnumerable<Prospect> whereas in your ReadAsAsync method you are passing IEnumerable<Foo> which obviously are not compatible types.

Install-Package Microsoft.AspNet.WebApi.Client

Select project in project manager console

What is the "realm" in basic authentication

According to the RFC 7235, the realm parameter is reserved for defining protection spaces (set of pages or resources where credentials are required) and it's used by the authentication schemes to indicate a scope of protection.

For more details, see the quote below (the highlights are not present in the RFC):

2.2. Protection Space (Realm)

The "realm" authentication parameter is reserved for use by authentication schemes that wish to indicate a scope of protection.

A protection space is defined by the canonical root URI (the scheme and authority components of the effective request URI) of the server being accessed, in combination with the realm value if present. These realms allow the protected resources on a server to be partitioned into a set of protection spaces, each with its own authentication scheme and/or authorization database. The realm value is a string, generally assigned by the origin server, that can have additional semantics specific to the authentication scheme. Note that a response can have multiple challenges with the same auth-scheme but with different realms. [...]

Note 1: The framework for HTTP authentication is currently defined by the RFC 7235, which updates the RFC 2617 and makes the RFC 2616 obsolete.

Note 2: The realm parameter is no longer always required on challenges.

How to set a string's color

Google aparently has a library for this sort of thing:

There's also a Javaworld article on this which solves your problem:

CSS: Auto resize div to fit container width

You could use css3 flexible box, it would go like this:

First your wrapper is wrapping a lot of things so you need a wrapper just for the 2 horizontal floated boxes:

 <div id="hor-box"> 
    <div id="left">
    <div id="content">

And your css3 should be:

  display: -webkit-box;
  display: -moz-box;
  display: box;

 -moz-box-orient: horizontal;
 box-orient: horizontal; 
 -webkit-box-orient: horizontal;

#left   {

     -webkit-box-flex: 0;
     -moz-box-flex: 0;
     box-flex: 0;  
#content   {

     -webkit-box-flex: 1;
     -moz-box-flex: 1;
      box-flex: 1; 

Changing upload_max_filesize on PHP

This solution can be applied only if the issue is on a WordPress installation!

If you don't have FTP access or too lazy to edit files,

You can use Increase Maximum Upload File Size plugin to increase the maximum upload file size.

How does one capture a Mac's command key via JavaScript?

if you use Vuejs, just make it by vue-shortkey plugin, everything will be simple

v-shortkey="['meta', 'enter']"·

When to use Comparable and Comparator

I would say that an object should implement Comparable if that is the clear natural way to sort the class, and anyone would need to sort the class would generally want to do it that way.

If, however, the sorting was an unusual use of the class, or the sorting only makes sense for a specific use case, then a Comparator is a better option.

Put another way, given the class name, is it clear how a comparable would sort, or do you have to resort to reading the javadoc? If it is the latter, odds are every future sorting use case would require a comparator, at which point the implementation of comparable may slow down users of the class, not speed them up.

Drop rows with all zeros in pandas data frame

Couple of solutions I found to be helpful while looking this up, especially for larger data sets:

df[(df.sum(axis=1) != 0)]       # 30% faster 
df[df.values.sum(axis=1) != 0]  # 3X faster 

Continuing with the example from @U2EF1:

In [88]: df = pd.DataFrame({'a':[0,0,1,1], 'b':[0,1,0,1]})

In [91]: %timeit df[(df.T != 0).any()]
1000 loops, best of 3: 686 µs per loop

In [92]: df[(df.sum(axis=1) != 0)]
   a  b
1  0  1
2  1  0
3  1  1

In [95]: %timeit df[(df.sum(axis=1) != 0)]
1000 loops, best of 3: 495 µs per loop

In [96]: %timeit df[df.values.sum(axis=1) != 0]
1000 loops, best of 3: 217 µs per loop

On a larger dataset:

In [119]: bdf = pd.DataFrame(np.random.randint(0,2,size=(10000,4)))

In [120]: %timeit bdf[(bdf.T != 0).any()]
1000 loops, best of 3: 1.63 ms per loop

In [121]: %timeit bdf[(bdf.sum(axis=1) != 0)]
1000 loops, best of 3: 1.09 ms per loop

In [122]: %timeit bdf[bdf.values.sum(axis=1) != 0]
1000 loops, best of 3: 517 µs per loop

What is

If your script is a directory or ZIP file rather than a single python file, will be executed when the "script" is passed as an argument to the python interpreter.

Check if a file exists in jenkins pipeline

You need to use brackets when using the fileExists step in an if condition or assign the returned value to a variable

Using variable:

def exists = fileExists 'file'

if (exists) {
    echo 'Yes'
} else {
    echo 'No'

Using brackets:

if (fileExists('file')) {
    echo 'Yes'
} else {
    echo 'No'

Find Item in ObservableCollection without using a loop

Well if you have N objects and you need to get the Title of all of them you have to use a loop. If you only need the title and you really want to improve this, maybe you can make a separated array containing only the title, this would improve the performance. You need to define the amount of memory available and the amount of objects that you can handle before saying this can damage the performance, and in any case the solution would be changing the design of the program not the algorithm.

How to Pass Parameters to Activator.CreateInstance<T>()


(T)Activator.CreateInstance(typeof(T), param1, param2);

Converting Numpy Array to OpenCV Array

Your code can be fixed as follows:

import numpy as np, cv
vis = np.zeros((384, 836), np.float32)
h,w = vis.shape
vis2 = cv.CreateMat(h, w, cv.CV_32FC3)
vis0 = cv.fromarray(vis)
cv.CvtColor(vis0, vis2, cv.CV_GRAY2BGR)

Short explanation:

  1. np.uint32 data type is not supported by OpenCV (it supports uint8, int8, uint16, int16, int32, float32, float64)
  2. cv.CvtColor can't handle numpy arrays so both arguments has to be converted to OpenCV type. cv.fromarray do this conversion.
  3. Both arguments of cv.CvtColor must have the same depth. So I've changed source type to 32bit float to match the ddestination.

Also I recommend you use newer version of OpenCV python API because it uses numpy arrays as primary data type:

import numpy as np, cv2
vis = np.zeros((384, 836), np.float32)
vis2 = cv2.cvtColor(vis, cv2.COLOR_GRAY2BGR)

css absolute position won't work with margin-left:auto margin-right: auto

If the element is position absolutely, then it isn't relative, or in reference to any object - including the page itself. So margin: auto; can't decide where the middle is.

Its waiting to be told explicitly, using left and top where to position itself.

You can still center it programatically, using javascript or somesuch.

Make an image responsive - the simplest way

Use Bootstrap to have a hustle free with your images as shown. Use class img-responsive and you are done:

<img src="cinqueterre.jpg" class="img-responsive" alt="Cinque Terre" width="304" height="236">

How to read a list of files from a folder using PHP?

There is this function scandir():

$dir = 'dir';
$files = scandir($dir, 0);
for($i = 2; $i < count($files); $i++)
    print $files[$i]."<br>";

More here in the manual

Powershell Get-ChildItem most recent file in directory

If you want the latest file in the directory and you are using only the LastWriteTime to determine the latest file, you can do something like below:

gci path | sort LastWriteTime | select -last 1

On the other hand, if you want to only rely on the names that have the dates in them, you should be able to something similar

gci path | select -last 1

Also, if there are directories in the directory, you might want to add a ?{-not $_.PsIsContainer}

JavaFX: How to get stage from controller during initialization?

I know it's not the answer you want, but IMO the proposed solutions are not good (and your own way is). Why? Because they depend on the application state. In JavaFX, a control, a scene and a stage do not depend on each other. This means a control can live without being added to a scene and a scene can exist without being attached to a stage. And then, at a time instant t1, control can get attached to a scene and at instant t2, that scene can be added to a stage (and that explains why they are observable properties of each other).

So the approach that suggests getting the controller reference and invoking a method, passing the stage to it adds a state to your application. This means you need to invoke that method at the right moment, just after the stage is created. In other words, you need to follow an order now: 1- Create the stage 2- Pass this created stage to the controller via a method.

You cannot (or should not) change this order in this approach. So you lost statelessness. And in software, generally, state is evil. Ideally, methods should not require any call order.

So what is the right solution? There are two alternatives:

1- Your approach, in the controller listening properties to get the stage. I think this is the right approach. Like this:

pane.sceneProperty().addListener((observableScene, oldScene, newScene) -> {
    if (oldScene == null && newScene != null) {
        // scene is set for the first time. Now its the time to listen stage changes.
        newScene.windowProperty().addListener((observableWindow, oldWindow, newWindow) -> {
            if (oldWindow == null && newWindow != null) {
                // stage is set. now is the right time to do whatever we need to the stage in the controller.
                ((Stage) newWindow).maximizedProperty().addListener((a, b, c) -> {
                    if (c) {
                        System.out.println("I am maximized!");

2- You do what you need to do where you create the Stage (and that's not what you want):

Stage stage = new Stage();
stage.maximizedProperty().addListener((a, b, c) -> {
            if (c) {
                System.out.println("I am maximized!");

How to change screen resolution of Raspberry Pi

You can change the display resolution graphically (without using Terminal) on Raspbian GNU/Linux 8 (jessie) using following window.

Application Menu > Preferences > Raspberry Pi Configuration > System > Set Resolution.

Click to view screenshots

What is the proof of of (N–1) + (N–2) + (N–3) + ... + 1= N*(N–1)/2

(N-1) + (N-2) +...+ 2 + 1 is a sum of N-1 items. Now reorder the items so, that after the first comes the last, then the second, then the second to last, i.e. (N-1) + 1 + (N-2) + 2 +... The way the items are ordered now you can see that each of those pairs is equal to N (N-1+1 is N, N-2+2 is N). Since there are N-1 items, there are (N-1)/2 such pairs. So you're adding N (N-1)/2 times, so the total value is N*(N-1)/2.

How to watch and compile all TypeScript sources?

EDIT: Note, this is if you have multiple tsconfig.json files in your typescript source. For my project we have each tsconfig.json file compile to a differently-named .js file. This makes watching every typescript file really easy.

I wrote a sweet bash script that finds all of your tsconfig.json files and runs them in the background, and then if you CTRL+C the terminal it will close all the running typescript watch commands.

This is tested on MacOS, but should work anywhere that BASH 3.2.57 is supported. Future versions may have changed some things, so be careful!

# run "chmod +x" in the directory of this file to ENABLE execution of this script
# then in terminal run "path/to/this/file/" to execute this script
# (or "./" if your terminal is in the folder the script is in)

# !!! CHANGE ME !!!    
# location of your scripts root folder
# make sure that you do not add a trailing "/" at the end!!
# also, no spaces! If you have a space in the filepath, then
# you have to follow this link:
# !!! CHANGE ME !!!

# find all typescript config files
scripts=$(find $sr -name "tsconfig.json")

for s in $scripts
    # strip off the word "tsconfig.json"
    cd ${s%/*} # */ # this function gets incorrectly parsed by style linters on web
    # run the typescript watch in the background
    tsc -w &
    # get the pid of the last executed background function
    # save it to an array
    pids+=" "

# end all processes we spawned when you close this process
wait $pids

Helpful resources:

Install php-mcrypt on CentOS 6

yum install php-mcrypt.x86_64

worked for me instead of

yum install php-mcrypt

Most common C# bitwise operations on enums

C++ operations are: & | ^ ~ (for and, or, xor and not bitwise operations). Also of interest are >> and <<, which are bitshift operations.

So, to test for a bit being set in a flag, you would use: if (flags & 8) //tests bit 4 has been set

How to bind event listener for rendered elements in Angular 2?

If you want to bind an event like 'click' for all the elements having same class in the rendered DOM element then you can set up an event listener by using following parts of the code in components.ts file.

import { Component, OnInit, Renderer, ElementRef} from '@angular/core';

constructor( elementRef: ElementRef, renderer: Renderer) {
    dragulaService.drop.subscribe((value) => {

public onDrop(args) {

  let [e, el] = args;



public toggleClassComTitle(el: any, name: string) {

    el.querySelectorAll('.com-item-title-anchor').forEach( function ( item ) {

      item.addEventListener('click', function(event) {




The insert or replace query would insert a new record if id=1 does not already exist.

The update query would only oudate id=1 if it aready exist, it would not create a new record if it didn't exist.

CSS: How to change colour of active navigation page menu

I think you are getting confused about what the a:active CSS selector does. This will only change the colour of your link when you click it (and only for the duration of the click i.e. how long your mouse button stays down). What you need to do is introduce a new class e.g. .selected into your CSS and when you select a link, update the selected menu item with new class e.g.

<div class="menuBar">
        <li class="selected"><a href="index.php">HOME</a></li>
        <li><a href="two.php">PORTFOLIO</a></li>

// specific CSS for your menu
div.menuBar li.selected a { color: #FF0000; } 
// more general CSS
li.selected a { color: #FF0000; }

You will need to update your template page to take in a selectedPage parameter.

How can I concatenate a string within a loop in JSTL/JSP?

define a String variable using the JSP tags

String test = new String();

then refer to that variable in your loop as

<c:forEach items="${myParams.items}" var="currentItem" varStatus="stat">
test+= whaterver_value

Recording video feed from an IP camera over a network

I haven't used it yet but I would take a look at The documentation explains you can install it on a modest machine with linux and use IP cameras for remote recording.


how to get current location in google map android

public void getMyLocation() {
        // create class object
        gps = new GPSTracker(HomeActivity.this);
        // check if GPS enabled
        if (gps.canGetLocation()) {
            latitude = gps.getLatitude();
            longitude = gps.getLongitude();
            Geocoder geocoder;
            List<Address> addresses;
            geocoder = new Geocoder(this, Locale.getDefault());
            try {
                addresses = geocoder.getFromLocation(latitude, longitude, 1);
                postalCode = addresses.get(0).getPostalCode();
                city = addresses.get(0).getLocality();
                address = addresses.get(0).getAddressLine(0);
                state = addresses.get(0).getAdminArea();
                country = addresses.get(0).getCountryName();
                knownName = addresses.get(0).getFeatureName();
                Log.e("Location",postalCode+" "+city+" "+address+" "+state+" "+knownName);

            } catch (IOException e) {
        } else {

How to change TextBox's Background color?

in web application in .cs page


in css specify it by using backcolor property

Add vertical scroll bar to panel

Panel has an AutoScroll property. Just set that property to True and the panel will automatically add a scroll bar when needed.

List comprehension with if statement

This is not a lambda function. It is a list comprehension.

Just change the order:

[ y for y in a if y not in b]

How to return a specific status code and no contents from Controller?

This code might work for non-.NET Core MVC controllers:

this.HttpContext.Response.StatusCode = 418; // I'm a teapot
return Json(new { status = "mer" }, JsonRequestBehavior.AllowGet);

Appending a vector to a vector

If you would like to add vector to itself both popular solutions will fail:

std::vector<std::string> v, orig;


// BAD:
v = orig;
v.insert(v.end(), v.begin(), v.end());
// Now v contains: { "first", "second", "", "" }

// BAD:
v = orig;
std::copy(v.begin(), v.end(), std::back_inserter(v));
// std::bad_alloc exception is generated

// GOOD, but I can't guarantee it will work with any STL:
v = orig;
v.insert(v.end(), v.begin(), v.end());
// Now v contains: { "first", "second", "first", "second" }

// GOOD, but I can't guarantee it will work with any STL:
v = orig;
std::copy(v.begin(), v.end(), std::back_inserter(v));
// Now v contains: { "first", "second", "first", "second" }

// GOOD (best):
v = orig;
v.insert(v.end(), orig.begin(), orig.end()); // note: we use different vectors here
// Now v contains: { "first", "second", "first", "second" }

Selenium: WebDriverException:Chrome failed to start: crashed as google-chrome is no longer running so ChromeDriver is assuming that Chrome has crashed

For RobotFramework

I solved it! using --no-sandbox

${chrome_options}=  Evaluate  sys.modules['selenium.webdriver'].ChromeOptions()  sys, selenium.webdriver
Call Method    ${chrome_options}    add_argument    test-type
Call Method    ${chrome_options}    add_argument    --disable-extensions
Call Method    ${chrome_options}    add_argument    --headless
Call Method    ${chrome_options}    add_argument    --disable-gpu
Call Method    ${chrome_options}    add_argument    --no-sandbox
Create Webdriver    Chrome    chrome_options=${chrome_options}

Instead of

Open Browser    about:blank    headlesschrome
Open Browser    about:blank    chrome

How to write loop in a Makefile?

For cross-platform support, make the command separator (for executing multiple commands on the same line) configurable.

If you're using MinGW on a Windows platform for example, the command separator is &:

NUMBERS = 1 2 3 4
    $(foreach number,$(NUMBERS),./a.out $(number) $(CMDSEP))

This executes the concatenated commands in one line:

./a.out 1 & ./a.out 2 & ./a.out 3 & ./a.out 4 &

As mentioned elsewhere, on a *nix platform use CMDSEP = ;.

form confirm before submit

Based on easy-confirm-plugin i did it:

(function($) {
    $.postconfirm = {};
    $.postconfirm.locales = {};
    $.postconfirm.locales.ptBR = {
        title: 'Esta certo disto?',
        text: 'Esta certo que quer realmente ?',
        button: ['Cancela', 'Confirma'],
        closeText: 'fecha'
    $.fn.postconfirm = function(options) {
        var options = jQuery.extend({
            eventType: 'click',
            icon: 'help'
        }, options);
        var locale = jQuery.extend({}, $.postconfirm.locales.ptBR, options.locale);
        var type = options.eventType;
        return this.each(function() {
            var target = this;
            var $target = jQuery(target);
            var getDlgDv = function() {
                var dlger = (options.dialog === undefined || typeof(options.dialog) != 'object');
                var dlgdv = $('<div class="dialog confirm">' + locale.text + '</div>');         
                return dlger ? dlgdv : options.dialog;          
            var dialog = getDlgDv();
            var handler = function(event) {
                    return false;
            var init = function() 
                $target.bind(type, handler); 
            var buttons = {};
            buttons[locale.button[0]] = function() { $(dialog).dialog("close"); };
            buttons[locale.button[1]] = function() {
                $target.unbind(type, handler);
                $target.attr("disabled", true);
                autoOpen: false,
                resizable: false,
                draggable: true,
                closeOnEscape: true,
                width: 'auto',
                minHeight: 120,
                maxHeight: 200,
                buttons: buttons,
                title: locale.title,
                closeText: locale.closeText,
                modal: true
        var _attr = $.fn.attr;
        $.fn.attr = function(attr, value) {
            var returned = _attr.apply(this, arguments);
            if (attr == 'title' && returned === undefined) 
                returned = '';
            return returned;

you only need call in this way:

    <script type="text/javascript">     
        $(document).ready(function () {
            $(".mybuttonselector").postconfirm({ locale: {
                        title: 'title',
                        text: 'message',
                        button: ['bt_0', 'bt_1'],
                        closeText: 'X'

Select parent element of known element in Selenium

There are a couple of options there. The sample code is in Java, but a port to other languages should be straightforward.


WebElement myElement = driver.findElement("myDiv"));
WebElement parent = (WebElement) ((JavascriptExecutor) driver).executeScript(
                                   "return arguments[0].parentNode;", myElement);


WebElement myElement = driver.findElement("myDiv"));
WebElement parent = myElement.findElement(By.xpath("./.."));

Obtaining the driver from the WebElement

Note: As you can see, for the JavaScript version you'll need the driver. If you don't have direct access to it, you can retrieve it from the WebElement using:

WebDriver driver = ((WrapsDriver) myElement).getWrappedDriver();

JFrame in full screen Java

You can use properties tool.
Set 2 properties for your JFrame:

extendedState 6
resizeable    true

How to set HttpResponse timeout for Android in Java

HttpParams httpParameters = new BasicHttpParams();
            HttpProtocolParams.setVersion(httpParameters, HttpVersion.HTTP_1_1);
            HttpProtocolParams.setUseExpectContinue(httpParameters, true);

            // Set the timeout in milliseconds until a connection is
            // established.
            // The default value is zero, that means the timeout is not used.
            int timeoutConnection = 35 * 1000;
            // Set the default socket timeout (SO_TIMEOUT)
            // in milliseconds which is the timeout for waiting for data.
            int timeoutSocket = 30 * 1000;
            HttpConnectionParams.setSoTimeout(httpParameters, timeoutSocket);

Eclipse: stop code from running (java)

Open the Console view, locate the console for your running app and hit the Big Red Button.

Alternatively if you open the Debug perspective you will see all running apps in (by default) the top left. You can select the one that's causing you grief and once again hit the Big Red Button.enter image description here

Change the class from factor to numeric of many columns in a data frame

Further to Ramnath's answer, the behaviour you are experiencing is that due to as.numeric(x) returning the internal, numeric representation of the factor x at the R level. If you want to preserve the numbers that are the levels of the factor (rather than their internal representation), you need to convert to character via as.character() first as per Ramnath's example.

Your for loop is just as reasonable as an apply call and might be slightly more readable as to what the intention of the code is. Just change this line:

stats[,i] <- as.numeric(stats[,i])

to read

stats[,i] <- as.numeric(as.character(stats[,i]))

This is FAQ 7.10 in the R FAQ.


How to convert SQL Query result to PANDAS Data Structure?

Simply use pandas and pyodbc together. You'll have to modify your connection string (connstr) according to your database specifications.

import pyodbc
import pandas as pd

# MSSQL Connection String Example
connstr = "Server=myServerAddress;Database=myDB;User Id=myUsername;Password=myPass;"

# Query Database and Create DataFrame Using Results
df = pd.read_sql("select * from myTable", pyodbc.connect(connstr))

I've used pyodbc with several enterprise databases (e.g. SQL Server, MySQL, MariaDB, IBM).

How to play a sound using Swift?

Most preferably you might want to use AVFoundation. It provides all the essentials for working with audiovisual media.

Update: Compatible with Swift 2, Swift 3 and Swift 4 as suggested by some of you in the comments.

Swift 2.3

import AVFoundation

var player: AVAudioPlayer?

func playSound() {
    let url = NSBundle.mainBundle().URLForResource("soundName", withExtension: "mp3")!

    do {
        player = try AVAudioPlayer(contentsOfURL: url)
        guard let player = player else { return }


    } catch let error as NSError {

Swift 3

import AVFoundation

var player: AVAudioPlayer?

func playSound() {
    guard let url = Bundle.main.url(forResource: "soundName", withExtension: "mp3") else { return }

    do {
        try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
        try AVAudioSession.sharedInstance().setActive(true)

        let player = try AVAudioPlayer(contentsOf: url)

    } catch let error {

Swift 4 (iOS 13 compatible)

import AVFoundation

var player: AVAudioPlayer?

func playSound() {
    guard let url = Bundle.main.url(forResource: "soundName", withExtension: "mp3") else { return }

    do {
        try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)            
        try AVAudioSession.sharedInstance().setActive(true)

        /* The following line is required for the player to work on iOS 11. Change the file type accordingly*/
        player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileType.mp3.rawValue)

        /* iOS 10 and earlier require the following line:
        player = try AVAudioPlayer(contentsOf: url, fileTypeHint: AVFileTypeMPEGLayer3) */

        guard let player = player else { return }

    } catch let error {

Make sure to change the name of your tune as well as the extension. The file needs to be properly imported (Project Build Phases > Copy Bundle Resources). You might want to place it in assets.xcassets for greater convenience.

For short sound files you might want to go for non-compressed audio formats such as .wav since they have the best quality and a low cpu impact. The higher disk-space consumption should not be a big deal for short sound files. The longer the files are, you might want to go for a compressed format such as .mp3 etc. pp. Check the compatible audio formats of CoreAudio.

Fun-fact: There are neat little libraries which make playing sounds even easier. :)
For example: SwiftySound

Reading and writing environment variables in Python?

Use os.environ[str(DEBUSSY)] for both reading and writing (

As for reading, you have to parse the number from the string yourself of course.

Vertically center text in a 100% height div?

have you tried line-height:1em;? I recall that that's the way to get it to center vertically.

How to save username and password in Git?

None of the answers above worked for me. I kept getting the following every time I wanted to fetch or pull:

Enter passphrase for key '/Users/myusername/.ssh/id_rsa':

For Macs

I was able to stop it from asking my passphrase by:

  1. Open config by running: vi ~/.ssh/config
  2. Added the following: UseKeychain yes
  3. Saved and quit: Press Esc, then enter :wq!

For Windows

I was able to get it to work using the info in this stackexchange:

Is there an "exists" function for jQuery?

There's no need for jQuery really. With plain JavaScript it's easier and semantically correct to check for:

if(document.getElementById("myElement")) {
    //Do something...

If for any reason you don't want to put an id to the element, you can still use any other JavaScript method designed to access the DOM.

jQuery is really cool, but don't let pure JavaScript fall into oblivion...

Get an image extension from an uploaded file in Laravel

return $picName = time().'.'.$request->file->extension();

The time() function will make the image unique then the .$request->file->extension() gets the image extension for you.

You can use this it works well with Laravel 6 and above.

Sort Java Collection

As of Java 8 you now can do it with a stream using a lambda:
             .foreach(object -> System.out.println(object));

Create a asmx web service in C# using visual studio 2013

on the web site box, you have selected .NETFramework 4.5 and it doesn show, so click there and choose the 3.5...i hope it helps.

How to change an application icon programmatically in Android?

To get the solution by Markus working I needed the first Intent so be:

Intent myLauncherIntent = new Intent(Intent.ACTION_MAIN);
            myLauncherIntent.setClassName(this,  this.getClass().getName());

Set background image in CSS using jquery

Try this:

<div class="rmz-srchbg">
    <input type="text" id="globalsearchstr" name="search" value="" class="rmz-txtbox">
    <input type="submit" value="&nbsp;" id="srchbtn" class="rmz-srchico">
    <br style="clear:both;">
   $('#globalsearchstr').on('focus mouseenter', function(){
    $(this).parent().css("background", "url(/images/r-srchbg_white.png) no-repeat");

ES6 class variable alternatives

If its only the cluttering what gives the problem in the constructor why not implement a initialize method that intializes the variables. This is a normal thing to do when the constructor gets to full with unnecessary stuff. Even in typed program languages like C# its normal convention to add an Initialize method to handle that.

SQL Server: Error converting data type nvarchar to numeric

I was running into this error while converting from nvarchar to float.
What I had to do was to use the LEFT function on the nvarchar field.

Example: Left(Field,4)

Basically, the query will look like:

Select convert(float,left(Field,4)) from TABLE

Just ridiculous that SQL would complicate it to this extent, while with C# it's a breeze!
Hope it helps someone out there.

How can getContentResolver() be called in Android?

import android.content.Context;
import android.content.ContentResolver;

context = (Context)this;
ContentResolver result = (ContentResolver)context.getContentResolver();

How to combine results of two queries into a single dataset

I think you are after something like this; (Using row_number() with CTE and performing a FULL OUTER JOIN )

Fiddle example

;with t1 as (
  select col1,col2, row_number() over (order by col1) rn
  from table1 
t2 as (
  select col3,col4, row_number() over (order by col3) rn
  from table2
select col1,col2,col3,col4
from t1 full outer join t2 on t1.rn = t2.rn

Tables and data :

create table table1 (col1 int, col2 int)
create table table2 (col3 int, col4 int)

insert into table1 values

insert into table2 values

Results :

|   COL1 |   COL2 | COL3 | COL4 |
|      1 |      2 |   10 |   11 |
|      3 |      4 |   30 |   40 |
| (null) | (null) |   50 |   60 |

Array vs ArrayList in performance

From here:

ArrayList is internally backed by Array in Java, any resize operation in ArrayList will slow down performance as it involves creating new Array and copying content from old array to new array.

In terms of performance Array and ArrayList provides similar performance in terms of constant time for adding or getting element if you know index. Though automatic resize of ArrayList may slow down insertion a bit Both Array and ArrayList is core concept of Java and any serious Java programmer must be familiar with these differences between Array and ArrayList or in more general Array vs List.

Error with multiple definitions of function

This problem happens because you are calling fun.cpp instead of fun.hpp. So c++ compiler finds func.cpp definition twice and throws this error.

Change line 3 of your main.cpp file, from #include "fun.cpp" to #include "fun.hpp" .

fatal: Not a git repository (or any of the parent directories): .git

The command has to be entered in the directory of the repository. The error is complaining that your current directory isn't a git repo

  1. Are you in the right directory? Does typing ls show the right files?
  2. Have you initialized the repository yet? Typed git init? (git-init documentation)

Either of those would cause your error.

How to run shell script on host from docker container?

If you are not worried about security and you're simply looking to start a docker container on the host from within another docker container like the OP, you can share the docker server running on the host with the docker container by sharing it's listen socket.

Please see and see if your personal risk tolerance allows this for this particular application.

You can do this by adding the following volume args to your start command

docker run -v /var/run/docker.sock:/var/run/docker.sock ...

or by sharing /var/run/docker.sock within your docker compose file like this:

version: '3'

      command: ...
      image: ...
         - /var/run/docker.sock:/var/run/docker.sock

When you run the docker start command within your docker container, the docker server running on your host will see the request and provision the sibling container.


What is the difference/usage of homebrew, macports or other package installation tools?

Currently, Macports has many more packages (~18.6 K) than there are Homebrew formulae (~3.1K), owing to its maturity. Homebrew is slowly catching up though.

Macport packages tend to be maintained by a single person.

Macports can keep multiple versions of packages around, and you can enable or disable them to test things out. Sometimes this list can get corrupted and you have to manually edit it to get things back in order, although this is not too hard.

Both package managers will ask to be regularly updated. This can take some time.

Note: you can have both package managers on your system! It is not one or the other. Brew might complain but Macports won't.

Also, if you are dealing with python or ruby packages, use a virtual environment wherever possible.

Getting the first character of a string with $str[0]

Speaking as a mere mortal, I would stick with $str[0]. As far as I'm concerned, it's quicker to grasp the meaning of $str[0] at a glance than substr($str, 0, 1). This probably boils down to a matter of preference.

As far as performance goes, well, profile profile profile. :) Or you could peer into the PHP source code...

Split string into list in jinja?

After coming back to my own question after 5 year and seeing so many people found this useful, a little update.

A string variable can be split into a list by using the split function (it can contain similar values, set is for the assignment) . I haven't found this function in the official documentation but it works similar to normal Python. The items can be called via an index, used in a loop or like Dave suggested if you know the values, it can set variables like a tuple.

{% set list1 = variable1.split(';') %}
The grass is {{ list1[0] }} and the boat is {{ list1[1] }}


{% set list1 = variable1.split(';') %}
{% for item in list1 %}
    <p>{{ item }}<p/>
{% endfor %} 


{% set item1, item2 = variable1.split(';') %}
The grass is {{ item1 }} and the boat is {{ item2 }}

How to set image name in Dockerfile?

Here is another version if you have to reference a specific docker file:

version: "3"
    container_name: nginx
      context: ../..
      dockerfile: ./docker/nginx/Dockerfile
    image: my_nginx:latest

Then you just run

docker-compose build

How to set a session variable when clicking a <a> link

Is your link to another web page? If so, perhaps you could put the variable in the query string and set the session variable when the page being linked to is loaded.

So the link looks like this:

<a href="home.php?variable=value" name="home">home</a>

And the homge page would parse the query string and set the session variable.

Set time to 00:00:00

If you need format 00:00:00 in string, you should use SimpleDateFormat as below. Using "H "instead "h".

Date today = new Date();
SimpleDateFormat ft = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss"); 
//not SimpleDateFormat("dd-MM-yyyy hh:mm:ss")
Calendar calendarDM = Calendar.getInstance();
calendarDM.set(Calendar.HOUR, 0);
calendarDM.set(Calendar.MINUTE, 0);
calendarDM.set(Calendar.SECOND, 0);
System.out.println("Current Date: " + ft.format(calendarDM.getTime()));

//Result is: Current Date: 29-10-2018 00:00:00

How to disable action bar permanently

Type this code to your onCreate method before setContentView:

getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, 0);

Separators for Navigation

Simply use the separator image as a background image on the li.

To get it to only appear in between list items, position the image to the left of the li, but not on the first one.

For example:

#nav li + li {
    background:url('seperator.gif') no-repeat top left;
    padding-left: 10px

This CSS adds the image to every list item that follows another list item - in other words all of them but the first.

NB. Be aware the adjacent selector (li + li) doesn't work in IE6, so you will have to just add the background image to the conventional li (with a conditional stylesheet) and perhaps apply a negative margin to one of the edges.

The transaction manager has disabled its support for remote/network transactions

Make sure that the "Distributed Transaction Coordinator" Service is running on both database and client. Also make sure you check "Network DTC Access", "Allow Remote Client", "Allow Inbound/Outbound" and "Enable TIP".

To enable Network DTC Access for MS DTC transactions

  1. Open the Component Services snap-in.

    To open Component Services, click Start. In the search box, type dcomcnfg, and then press ENTER.

  2. Expand the console tree to locate the DTC (for example, Local DTC) for which you want to enable Network MS DTC Access.

  3. On the Action menu, click Properties.

  4. Click the Security tab and make the following changes: In Security Settings, select the Network DTC Access check box.

    In Transaction Manager Communication, select the Allow Inbound and Allow Outbound check boxes.

How to filter by string in JSONPath?

Your query looks fine, and your data and query work for me using this JsonPath parser. Also see the example queries on that page for more predicate examples.

The testing tool that you're using seems faulty. Even the examples from the JsonPath site are returning incorrect results:

e.g., given:

            { "category": "reference",
              "author": "Nigel Rees",
              "title": "Sayings of the Century",
              "price": 8.95
            { "category": "fiction",
              "author": "Evelyn Waugh",
              "title": "Sword of Honour",
              "price": 12.99
            { "category": "fiction",
              "author": "Herman Melville",
              "title": "Moby Dick",
              "isbn": "0-553-21311-3",
              "price": 8.99
            { "category": "fiction",
              "author": "J. R. R. Tolkien",
              "title": "The Lord of the Rings",
              "isbn": "0-395-19395-8",
              "price": 22.99
            "color": "red",
            "price": 19.95

And the expression: $[?(@.length-1)].title, the tool returns a list of all titles.

Can a Windows batch file determine its own file name?

Try to run below example in order to feel how the magical variables work.

@echo off

SETLOCAL EnableDelayedExpansion

echo Full path and filename: %~f0
echo Drive: %~d0
echo Path: %~p0
echo Drive and path: %~dp0
echo Filename without extension: %~n0
echo Filename with    extension: %~nx0
echo Extension: %~x0

echo date time : %~t0
echo file size: %~z0


The related rules are following.

%~I         - expands %I removing any surrounding quotes ("")
%~fI        - expands %I to a fully qualified path name
%~dI        - expands %I to a drive letter only
%~pI        - expands %I to a path only
%~nI        - expands %I to a file name only
%~xI        - expands %I to a file extension only
%~sI        - expanded path contains short names only
%~aI        - expands %I to file attributes of file
%~tI        - expands %I to date/time of file
%~zI        - expands %I to size of file
%~$PATH:I   - searches the directories listed in the PATH
               environment variable and expands %I to the
               fully qualified name of the first one found.
               If the environment variable name is not
               defined or the file is not found by the
               search, then this modifier expands to the
               empty string

SQLAlchemy: What's the difference between flush() and commit()?

A Session object is basically an ongoing transaction of changes to a database (update, insert, delete). These operations aren't persisted to the database until they are committed (if your program aborts for some reason in mid-session transaction, any uncommitted changes within are lost).

The session object registers transaction operations with session.add(), but doesn't yet communicate them to the database until session.flush() is called.

session.flush() communicates a series of operations to the database (insert, update, delete). The database maintains them as pending operations in a transaction. The changes aren't persisted permanently to disk, or visible to other transactions until the database receives a COMMIT for the current transaction (which is what session.commit() does).

session.commit() commits (persists) those changes to the database.

flush() is always called as part of a call to commit() (1).

When you use a Session object to query the database, the query will return results both from the database and from the flushed parts of the uncommitted transaction it holds. By default, Session objects autoflush their operations, but this can be disabled.

Hopefully this example will make this clearer:

s = Session()

s.add(Foo('A')) # The Foo('A') object has been added to the session.
                # It has not been committed to the database yet,
                #   but is returned as part of a query.
print 1, s.query(Foo).all()

s2 = Session()
s2.autoflush = False

print 2, s2.query(Foo).all() # The Foo('B') object is *not* returned
                             #   as part of this query because it hasn't
                             #   been flushed yet.
s2.flush()                   # Now, Foo('B') is in the same state as
                             #   Foo('A') was above.
print 3, s2.query(Foo).all() 
s2.rollback()                # Foo('B') has not been committed, and rolling
                             #   back the session's transaction removes it
                             #   from the session.
print 4, s2.query(Foo).all()

1 [<Foo('A')>]
2 [<Foo('A')>]
3 [<Foo('A')>, <Foo('B')>]
4 [<Foo('A')>]

How to fix "ImportError: No module named ..." error in Python?

In my mind I have to consider that the foo folder is a stand-alone library. I might want to consider moving it to the Lib\site-packages folder within a python installation. I might want to consider adding a foo.pth file there.

I know it's a library since the ./programs/ contains the following line:

from foo.tasks import my_function

So it doesn't matter that ./programs is a sibling folder to ./foo. It's the fact that is run as a script like this:

python ./programs/

bower proxy configuration

Edit your .bowerrc file ( should be next to your bower.json file ) and add the wanted proxy configuration


TLS 1.2 not working in cURL

TLS 1.1 and TLS 1.2 are supported since OpenSSL 1.0.1

Forcing TLS 1.1 and 1.2 are only supported since curl 7.34.0

You should consider an upgrade.

MongoDb shuts down with Code 100

To run Mongo DB demon with mongod command, you should have a database directory, probably you need to run:

mkdir C:\data\db

Also, MongoDB need to have a write permissions for that directory or it should be run with superuser permissions, like sudo mongod.

Change the Arrow buttons in Slick slider

You can use FontAwesome "content" values and apply as follow by css. These apply "chevron right/left" icons.

.custom-slick .slick-prev:before {
    content: "?";
    font-family: 'FontAwesome';
    font-size: 22px;
.custom-slick .slick-next:before {
    content: "?";
    font-family: 'FontAwesome';
    font-size: 22px;

Crontab Day of the Week syntax

0 and 7 both stand for Sunday, you can use the one you want, so writing 0-6 or 1-7 has the same result.

Also, as suggested by @Henrik, it is possible to replace numbers by shortened name of days, such as MON, THU, etc:

0 - Sun      Sunday
1 - Mon      Monday
2 - Tue      Tuesday
3 - Wed      Wednesday
4 - Thu      Thursday
5 - Fri      Friday
6 - Sat      Saturday
7 - Sun      Sunday


 +---------- minute (0 - 59)
 ¦ +-------- hour (0 - 23)
 ¦ ¦ +------ day of month (1 - 31)
 ¦ ¦ ¦ +---- month (1 - 12)
 ¦ ¦ ¦ ¦ +-- day of week (0 - 6 => Sunday - Saturday, or
 ¦ ¦ ¦ ¦ ¦                1 - 7 => Monday - Sunday)
 ? ? ? ? ?
 * * * * * command to be executed

Finally, if you want to specify day by day, you can separate days with commas, for example SUN,MON,THU will exectute the command only on sundays, mondays on thursdays.

You can read further details in Wikipedia's article about Cron.

Postfix is installed but how do I test it?

To check whether postfix is running or not

sudo postfix status

If it is not running, start it.

sudo postfix start

Then telnet to localhost port 25 to test the email id

ehlo localhost
mail from: root@localhost
rcpt to: your_email_id
Subject: My first mail on Postfix

Are you there?

Do not forget the . at the end, which indicates end of line

Currency formatting in Python

Oh, that's an interesting beast.

I've spent considerable time of getting that right, there are three main issues that differs from locale to locale: - currency symbol and direction - thousand separator - decimal point

I've written my own rather extensive implementation of this which is part of the kiwi python framework, check out the LGPL:ed source here:

The code is slightly Linux/Glibc specific, but shouldn't be too difficult to adopt to windows or other unixes.

Once you have that installed you can do the following:

>>> from kiwi.datatypes import currency
>>> v = currency('10.5').format()

Which will then give you:



'10,50 kr'

Depending on the currently selected locale.

The main point this post has over the other is that it will work with older versions of python. locale.currency was introduced in python 2.5.

How can I use a search engine to search for special characters?

Unfortunately, there doesn't appear to be a magic bullet. Bottom line up front: "context".

Google indeed ignores most punctuation, with the following exceptions:

  1. Punctuation in popular terms that have particular meanings, like [ C++ ] or [ C# ] (both are names of programming languages), are not ignored.
  2. The dollar sign ($) is used to indicate prices. [ nikon 400 ] and [ nikon $400 ] will give different results.
  3. The hyphen - is sometimes used as a signal that the two words around it are very strongly connected. (Unless there is no space after the - and a space before it, in which case it is a negative sign.)
  4. The underscore symbol _ is not ignored when it connects two words, e.g. [ quick_sort ].

As such, it is not well suited for these types of searchs. Google Code however does have syntax for searching through their code projects, that includes a robust language/syntax for dealing with "special characters". If looking at someone else's code could help solve a problem, this may be an option.

Unfortunately, this is not a limitation unique to google. You may find that your best successes hinge on providing as much 'context' to the problem as possible. If you are searching to find what $- means, providing information about the problem's domain may yield good results.

For example, searching "special perl variables" quickly yields your answer in the first entry on the results page.

a tag as a submit button?

Supposing the form is the direct parent you can do:

<a href='#' onclick='this.parentNode.submit(); return false;'>submit</a>

If not you can access through the forms name attribute like this:

<a href='#' onclick='document.forms["myform"].submit(); return false;'>submit</a>

See both examples here:

How to list the files inside a JAR file?

Just a different way of listing/reading files from a jar URL and it does it recursively for nested jars

URL urlResource = Thead.currentThread().getContextClassLoader().getResource("foo");, new InputStreamCallback() {
    public void onFile(String name, InputStream is) throws IOException {
        // got file name and content stream 

open cv error: (-215) scn == 3 || scn == 4 in function cvtColor

Give the full path of image with forward slash. It solved the error for me.


import numpy as np
import cv2

img = cv2.imread('C:/Python34/images/2015-05-27-191152.jpg')
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

Also, if you give 0 in second parameter while loading image using cv2.imread than no need to convert image using cvtColor, it is already loaded as grayscale image eg.

import numpy as np
import cv2

gray = cv2.imread('C:/Python34/images/2015-05-27-191152.jpg',0)

Aggregate function in SQL WHERE-Clause

Another solution is to Move the aggregate fuction to Scalar User Defined Function

Create Your Function:

CREATE FUNCTION getTotalSalesByProduct(@ProductName VARCHAR(500))

DECLARE @TotalAmount INT

SET @TotalAmount = (select SUM(SaleAmount) FROM Sales where Product=@ProductName)

RETURN @TotalAmount


Use Function in Where Clause

SELECT ProductName, SUM(SaleAmount) AS TotalSales
FROM Sales
WHERE dbo.getTotalSalesByProduct(ProductName)  > 1000
GROUP BY Product


1. 2.

Hope helps someone.

How can I display a messagebox in ASP.NET?

The best solution is a minimal use of java directly in the visualstudio GUI

here it is: On a button go to the "OnClientClick" property (its not into events*) overthere type:

return confirm('are you sure?')

it will put a dialog with cancel ok buttons transparent over current page if cancel is pressed no postback will ocure. However if you want only ok button type:

alert ('i told you so')

The events like onclick work server side they execute your code, while OnClientClick runs in the browser side. the come most close to a basic dialog

Check if table exists

I don't actually find any of the presented solutions here to be fully complete so I'll add my own. Nothing new here. You can stitch this together from the other presented solutions plus various comments.

There are at least two things you'll have to make sure:

  1. Make sure you pass the table name to the getTables() method, rather than passing a null value. In the first case you let the database server filter the result for you, in the second you request a list of all tables from the server and then filter the list locally. The former is much faster if you are only searching for a single table.

  2. Make sure to check the table name from the resultset with an equals match. The reason is that the getTables() does pattern matching on the query for the table and the _ character is a wildcard in SQL. Suppose you are checking for the existence of a table named EMPLOYEE_SALARY. You'll then get a match on EMPLOYEESSALARY too which is not what you want.

Ohh, and do remember to close those resultsets. Since Java 7 you would want to use a try-with-resources statement for that.

Here's a complete solution:

public static boolean tableExist(Connection conn, String tableName) throws SQLException {
    boolean tExists = false;
    try (ResultSet rs = conn.getMetaData().getTables(null, null, tableName, null)) {
        while ( { 
            String tName = rs.getString("TABLE_NAME");
            if (tName != null && tName.equals(tableName)) {
                tExists = true;
    return tExists;

You may want to consider what you pass as the types parameter (4th parameter) on your getTables() call. Normally I would just leave at null because you don't want to restrict yourself. A VIEW is as good as a TABLE, right? These days many databases allow you to update through a VIEW so restricting yourself to only TABLE type is in most cases not the way to go. YMMV.

diff current working copy of a file with another branch's committed copy

The following works for me:

git diff master:foo foo

In the past, it may have been:

git diff foo master:foo

HTML5 phone number validation with pattern

This code will accept all country code with + sign

<input type="text" pattern="[0-9]{5}[-][0-9]{7}[-][0-9]{1}"/>

Some countries allow a single "0" character instead of "+" and others a double "0" character instead of the "+". Neither are standard.

How do I verify/check/test/validate my SSH passphrase?

ssh-keygen -y

ssh-keygen -y will prompt you for the passphrase (if there is one).

    If you input the correct passphrase, it will show you the associated public key.
    If you input the wrong passphrase, it will display load failed.
    If the key has no passphrase, it will not prompt you for a passphrase and will immediately show you the associated public key.


Create a new public/private key pair, with or without a passphrase:

$ ssh-keygen -f /tmp/my_key

Now see if you can access the key pair:

$ ssh-keygen -y -f /tmp/my_key

Following is an extended example, showing output.

Create a new public/private key pair, with or without a passphrase:

$ ssh-keygen -f /tmp/my_key
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /tmp/my_key.
Your public key has been saved in /tmp/
The key fingerprint is:
de:24:1b:64:06:43:ca:76:ba:81:e5:f2:59:3b:81:fe [email protected]
The key's randomart image is:
+--[ RSA 2048]----+
|     .+          |
|   . . o         |
|    = . +        |
|   = + +         |
|  o = o S .      |
|   + = + *       |
|    = o o .      |
|     . .         |
|      E          |

Attempt to access the key pair by inputting the correct passphrase. Note that the public key will be shown and the exit status ($?) will be 0 to indicate success:

$ ssh-keygen -y -f /tmp/my_key
Enter passphrase:
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDBJhVYDYxXOvcQw0iJTPY64anbwSyzI58hht6xCGJ2gzGUJDIsr1NDQsclka6s0J9TNhUEBBzKvh9nTAYibXwwhIqBwJ6UwWIfA3HY13WS161CUpuKv2A/PrfK0wLFBDBlwP6WjwJNfi4NwxA21GUS/Vcm/SuMwaFid9bM2Ap4wZIahx2fxyJhmHugGUFF9qYI4yRJchaVj7TxEmquCXgVf4RVWnOSs9/MTH8YvH+wHP4WmUzsDI+uaF1SpCyQ1DpazzPWAQPgZv9R8ihOrItLXC1W6TPJkt1CLr/YFpz6vapdola8cRw6g/jTYms00Yxf2hn0/o8ORpQ9qBpcAjJN
$ echo $?

Attempt to access the key pair by inputting an incorrect passphrase. Note that the "load failed" error message will be displayed (message may differ depending on OS) and the exit status ($?) will be 1 to indicate an error:

$ ssh-keygen -y -f /tmp/my_key
Enter passphrase:
load failed
$ echo $?

Attempt to access a key pair that has no passphrase. Note that there is no prompt for the passphrase, the public key will be displayed, and the exit status ($?) will be 0 to indicate success:

$ ssh-keygen -y -f /tmp/my_key_with_no_passphrase
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDLinxx9T4HE6Brw2CvFacvFrYcOSoQUmwL4Cld4enpg8vEiN8DB2ygrhFtKVo0qMAiGWyqz9gXweXhdmAIsVXqhOJIQvD8FqddA/SMgqM++2M7GxgH68N+0V+ih7EUqf8Hb2PIeubhkQJQGzB3FjYkvRLZqE/oC1Q5nL4B1L1zDQYPSnQKneaRNG/NGIaoVwsy6gcCZeqKHywsXBOHLF4F5nf/JKqfS6ojStvzajf0eyQcUMDVhdxTN/hIfEN/HdYbOxHtwDoerv+9f6h2OUxZny1vRNivZxTa+9Qzcet4tkZWibgLmqRyFeTcWh+nOJn7K3puFB2kKoJ10q31Tq19
$ echo $?

Note that the order of arguments is important. -y must come before -f input_keyfile, else you will get the error Too many arguments..

How to remove .html from URL?

For those who are using Firebase hosting none of the answers will work on this page. Because you can't use .htaccess in Firebase hosting. You will have to configure the firebase.json file. Just add the line "cleanUrls": true in your file and save it. That's it.

After adding the line firebase.json will look like this :

  "hosting": {
    "public": "public",
    "cleanUrls": true, 
    "ignore": [

Remove part of a string

You can use a built-in for this, strsplit:

> s = "TGAS_1121"
> s1 = unlist(strsplit(s, split='_', fixed=TRUE))[2]
> s1    
 [1] "1121"

strsplit returns both pieces of the string parsed on the split parameter as a list. That's probably not what you want, so wrap the call in unlist, then index that array so that only the second of the two elements in the vector are returned.

Finally, the fixed parameter should be set to TRUE to indicate that the split parameter is not a regular expression, but a literal matching character.

ORA-00907: missing right parenthesis

ORA-00907: missing right parenthesis

This is one of several generic error messages which indicate our code contains one or more syntax errors. Sometimes it may mean we literally have omitted a right bracket; that's easy enough to verify if we're using an editor which has a match bracket capability (most text editors aimed at coders do). But often it means the compiler has come across a keyword out of context. Or perhaps it's a misspelled word, a space instead of an underscore or a missing comma.

Unfortunately the possible reasons why our code won't compile is virtually infinite and the compiler just isn't clever enough to distinguish them. So it hurls a generic, slightly cryptic, message like ORA-00907: missing right parenthesis and leaves it to us to spot the actual bloomer.

The posted script has several syntax errors. First I will discuss the error which triggers that ORA-0097 but you'll need to fix them all.

Foreign key constraints can be declared in line with the referencing column or at the table level after all the columns have been declared. These have different syntaxes; your scripts mix the two and that's why you get the ORA-00907.

In-line declaration doesn't have a comma and doesn't include the referencing column name.

CREATE TABLE historys_T    (
    history_record    VARCHAR2 (8),
    customer_id       VARCHAR2 (8) 
    order_id           VARCHAR2 (10) NOT NULL,
          CONSTRAINT fk_order_id_orders REFERENCES orders ON DELETE CASCADE)

Table level constraints are a separate component, and so do have a comma and do mention the referencing column.

CREATE TABLE historys_T    (
    history_record    VARCHAR2 (8),
    customer_id       VARCHAR2 (8),    
    order_id           VARCHAR2 (10) NOT NULL,
    CONSTRAINT historys_T_FK FOREIGN KEY (customer_id) REFERENCES T_customers ON DELETE CASCADE,   
   CONSTRAINT fk_order_id_orders FOREIGN KEY (order_id) REFERENCES orders ON DELETE CASCADE)

Here is a list of other syntax errors:

  1. The referenced table (and the referenced primary key or unique constraint) must already exist before we can create a foreign key against them. So you cannot create a foreign key for HISTORYS_T before you have created the referenced ORDERS table.
  2. You have misspelled the names of the referenced tables in some of the foreign key clauses (LIBRARY_T and FORMAT_T).
  3. You need to provide an expression in the DEFAULT clause. For DATE columns that is usually the current date, DATE DEFAULT sysdate.

Looking at our own code with a cool eye is a skill we all need to gain to be successful as developers. It really helps to be familiar with Oracle's documentation. A side-by-side comparison of your code and the examples in the SQL Reference would have helped you resolved these syntax errors in considerably less than two days. Find it here (11g) and here (12c).

As well as syntax errors, your scripts contain design mistakes. These are not failures, but bad practice which should not become habits.

  1. You have not named most of your constraints. Oracle will give them a default name but it will be a horrible one, and makes the data dictionary harder to understand. Explicitly naming every constraint helps us navigate the physical database. It also leads to more comprehensible error messages when our SQL trips a constraint violation.
  2. Name your constraints consistently. HISTORY_T has constraints called historys_T_FK and fk_order_id_orders, neither of which is helpful. A useful convention is <child_table>_<parent_table>_fk. So history_customer_fk and history_order_fk respectively.
  3. It can be useful to create the constraints with separate statements. Creating tables then primary keys then foreign keys will avoid the problems with dependency ordering identified above.
  4. You are trying to create cyclic foreign keys between LIBRARY_T and FORMATS. You could do this by creating the constraints in separate statement but don't: you will have problems when inserting rows and even worse problems with deletions. You should reconsider your data model and find a way to model the relationship between the two tables so that one is the parent and the other the child. Or perhaps you need a different kind of relationship, such as an intersection table.
  5. Avoid blank lines in your scripts. Some tools will handle them but some will not. We can configure SQL*Plus to handle them but it's better to avoid the need.
  6. The naming convention of LIBRARY_T is ugly. Try to find a more expressive name which doesn't require a needless suffix to avoid a keyword clash.
  7. T_CUSTOMERS is even uglier, being both inconsistent with your other tables and completely unnecessary, as customers is not a keyword.

Naming things is hard. You wouldn't believe the wrangles I've had about table names over the years. The most important thing is consistency. If I look at a data dictionary and see tables called T_CUSTOMERS and LIBRARY_T my first response would be confusion. Why are these tables named with different conventions? What conceptual difference does this express? So, please, decide on a naming convention and stick to. Make your table names either all singular or all plural. Avoid prefixes and suffixes as much as possible; we already know it's a table, we don't need a T_ or a _TAB.

Get connection status on client

@robertklep's answer to check socket.connected is correct except for reconnect event, As the document said it is "Fired upon a successful reconnection." but when you check socket.connected then it is false.

Not sure it is a bug or intentional.

Align an element to bottom with flexbox

1. Style parent element: style="display:flex; flex-direction:column; flex:1;"

2. Style the element you want to stay at bottom: style="margin-top: auto;"

3. Done! Wow. That was easy.


enter image description here

<section style="display:flex; flex-wrap:wrap;"> // For demo, not necessary
    <div style="display:flex; flex-direction:column; flex:1;"> // Parent element
        <button style="margin-top: auto;"> I </button> // Target element

    ... 5 more identical divs, for demo ...



Could not load file or assembly ... An attempt was made to load a program with an incorrect format (System.BadImageFormatException)

In my case the error was System.BadImageFormatException: Could not load file or assembly 'vjslib, Version=, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies.

It was solved by installing vjredist 64 from here.

Remove the last line from a file in Bash

Here's how you can do it manually (I personally use this method a lot when I need to quickly remove the last line in a file):

vim + [FILE]

That + sign there means that when the file is opened in the vim text editor, the cursor will be positioned on the last line of the file.

Now just press d twice on your keyboard. This will do exactly what you want—remove the last line. After that, press : followed by x and then press Enter. This will save the changes and bring you back to the shell. Now, the last line has been successfully removed.

Convert json data to a html table

Thanks all for your replies. I wrote one myself. Please note that this uses jQuery.

Code snippet:

var myList = [_x000D_
  { "name": "abc", "age": 50 },_x000D_
  { "age": "25", "hobby": "swimming" },_x000D_
  { "name": "xyz", "hobby": "programming" }_x000D_
// Builds the HTML Table out of myList._x000D_
function buildHtmlTable(selector) {_x000D_
  var columns = addAllColumnHeaders(myList, selector);_x000D_
  for (var i = 0; i < myList.length; i++) {_x000D_
    var row$ = $('<tr/>');_x000D_
    for (var colIndex = 0; colIndex < columns.length; colIndex++) {_x000D_
      var cellValue = myList[i][columns[colIndex]];_x000D_
      if (cellValue == null) cellValue = "";_x000D_
// Adds a header row to the table and returns the set of columns._x000D_
// Need to do union of keys from all records as some records may not contain_x000D_
// all records._x000D_
function addAllColumnHeaders(myList, selector) {_x000D_
  var columnSet = [];_x000D_
  var headerTr$ = $('<tr/>');_x000D_
  for (var i = 0; i < myList.length; i++) {_x000D_
    var rowHash = myList[i];_x000D_
    for (var key in rowHash) {_x000D_
      if ($.inArray(key, columnSet) == -1) {_x000D_
  return columnSet;_x000D_
<script src=""></script>_x000D_
<body onLoad="buildHtmlTable('#excelDataTable')">_x000D_
  <table id="excelDataTable" border="1">_x000D_

How to use conditional breakpoint in Eclipse?

Put your breakpoint. Right-click the breakpoint image on the margin and choose Breakpoint Properties:

enter image description here

Configure condition as you see fit:

enter image description here

What do two question marks together mean in C#?

Some of the examples here of getting values using coalescing are inefficient.

What you really want is:

return _formsAuthWrapper = _formsAuthWrapper ?? new FormsAuthenticationWrapper();


return _formsAuthWrapper ?? (_formsAuthWrapper = new FormsAuthenticationWrapper());

This prevents the object from being recreated every time. Instead of the private variable remaining null and a new object getting created on every request, this ensures the private variable is assigned if the new object is created.

Writing a pandas DataFrame to CSV file

To delimit by a tab you can use the sep argument of to_csv:

df.to_csv(file_name, sep='\t')

To use a specific encoding (e.g. 'utf-8') use the encoding argument:

df.to_csv(file_name, sep='\t', encoding='utf-8')

How to remove an HTML element using Javascript?

This works. Just remove the button from the "dummy" div if you want to keep the button.

function removeDummy() {_x000D_
  var elem = document.getElementById('dummy');_x000D_
  return false;_x000D_
#dummy {_x000D_
  min-width: 200px;_x000D_
  min-height: 200px;_x000D_
  max-width: 200px;_x000D_
  max-height: 200px;_x000D_
  background-color: #fff000;_x000D_
<div id="dummy">_x000D_
  <button onclick="removeDummy()">Remove</button>_x000D_

Where can I download the jar for org.apache.http package?

Download servlet-api.jar That has all the files below:



Keyboard shortcut to "untab" (move a block of code to the left) in eclipse / aptana?

Don't know if anyone is still looking here, but you can do this by going to Window menu > Preferences, then open the General list, choose keys. Scroll down the list of keys until you see "Shift Left". Click that. Below that you'll see some boxes, one of which lets you bind a key. It won't accept Shift-Tab, so I bound it to Shift-`. Apply-and-close and you're all set.

Node.js Best Practice Exception Handling

After reading this post some time ago I was wondering if it was safe to use domains for exception handling on an api / function level. I wanted to use them to simplify exception handling code in each async function I wrote. My concern was that using a new domain for each function would introduce significant overhead. My homework seems to indicate that there is minimal overhead and that performance is actually better with domains than with try catch in some situations.

How to resolve the "EVP_DecryptFInal_ex: bad decrypt" during file decryption

Errors: "Bad encrypt / decrypt" "gitencrypt_smudge: FAILURE: openssl error decrypting file"

There are various error strings that are thrown from openssl, depending on respective versions, and scenarios. Below is the checklist I use in case of openssl related issues:

  1. Ideally, openssl is able to encrypt/decrypt using same key (+ salt) & enc algo only.
  2. Ensure that openssl versions (used to encrypt/decrypt), are compatible. For eg. the hash used in openssl changed at version 1.1.0 from MD5 to SHA256. This produces a different key from the same password. Fix: add "-md md5" in 1.1.0 to decrypt data from lower versions, and add "-md sha256 in lower versions to decrypt data from 1.1.0

  3. Ensure that there is a single openssl version installed in your machine. In case there are multiple versions installed simultaneously (in my machine, these were installed :- 'LibreSSL 2.6.5' and 'openssl 1.1.1d'), make the sure that only the desired one appears in your PATH variable.

Select Tag Helper in ASP.NET Core MVC

In Get:

public IActionResult Create()
    ViewData["Tags"] = new SelectList(_context.Tags, "Id", "Name");
    return View();

In Post:

var selectedIds= Request.Form["Tags"];

In View :

<select  asp-for="Tags"  id="Tags" name="Tags" class="form-control" asp-items="ViewBag.Tags" multiple></select>

T-SQL STOP or ABORT command in SQL Server

I know the question is old and was answered correctly in few different ways but there is no answer as mine which I have used in similar situations. First approach (very basic):

IF (1=0)
    PRINT 'it will not go there'
    -- your script here
PRINT 'but it will here'

Second approach:

PRINT 'stop here'
    -- your script here
PRINT 'it will not go there'

You can test it easily by yourself to make sure it behave as expected.

Understanding ASP.NET Eval() and Bind()

The question was answered perfectly by Darin Dimitrov, but since ASP.NET 4.5, there is now a better way to set up these bindings to replace* Eval() and Bind(), taking advantage of the strongly-typed bindings.

*Note: this will only work if you're not using a SqlDataSource or an anonymous object. It requires a Strongly-typed object (from an EF model or any other class).

This code snippet shows how Eval and Bind would be used for a ListView control (InsertItem needs Bind, as explained by Darin Dimitrov above, and ItemTemplate is read-only (hence they're labels), so just needs an Eval):

<asp:ListView ID="ListView1" runat="server" DataKeyNames="Id" InsertItemPosition="LastItem" SelectMethod="ListView1_GetData" InsertMethod="ListView1_InsertItem" DeleteMethod="ListView1_DeleteItem">
            Title: <asp:TextBox ID="Title" runat="server" Text='<%# Bind("Title") %>'/><br />         
            Description: <asp:TextBox ID="Description" runat="server" TextMode="MultiLine" Text='<%# Bind("Description") %>' /><br />        
            <asp:Button ID="InsertButton" runat="server" Text="Insert" CommandName="Insert" />        
            Title: <asp:Label ID="Title" runat="server" Text='<%#  Eval("Title") %>' /><br />
            Description: <asp:Label ID="Description" runat="server" Text='<%# Eval("Description") %>' /><br />        
            <asp:Button ID="DeleteButton" runat="server" Text="Delete" CommandName="Delete" CausesValidation="false"/>

From ASP.NET 4.5+, data-bound controls have been extended with a new property ItemType, which points to the type of object you're assigning to its data source.

<asp:ListView ItemType="Picture" ID="ListView1" runat="server" ...>

Picture is the strongly type object (from EF model). We then replace:

Bind(property) ->
Eval(property) ->

So this:

<%# Bind("Title") %>      
<%# Bind("Description") %>         
<%#  Eval("Title") %> 
<%# Eval("Description") %>

Would become this:

<%# BindItem.Title %>         
<%# BindItem.Description %>
<%# Item.Title %>
<%# Item.Description %>

Advantages over Eval & Bind:

  • IntelliSense can find the correct property of the object your're working withenter image description here
  • If property is renamed/deleted, you will get an error before page is viewed in browser
  • External tools (requires full versions of VS) will correctly rename item in markup when you rename a property on your object

Source: from this excellent book

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

When Modernizr runs, it removes the "no-js" class and replaces it with "js". This is a way to apply different CSS rules depending on whether or not Javascript support is enabled.

See Modernizer's source code.

How to update Git clone

git pull origin master

this will sync your master to the central repo and if new branches are pushed to the central repo it will also update your clone copy.

How to create materialized views in SQL Server?

You might need a bit more background on what a Materialized View actually is. In Oracle these are an object that consists of a number of elements when you try to build it elsewhere.

An MVIEW is essentially a snapshot of data from another source. Unlike a view the data is not found when you query the view it is stored locally in a form of table. The MVIEW is refreshed using a background procedure that kicks off at regular intervals or when the source data changes. Oracle allows for full or partial refreshes.

In SQL Server, I would use the following to create a basic MVIEW to (complete) refresh regularly.

First, a view. This should be easy for most since views are quite common in any database Next, a table. This should be identical to the view in columns and data. This will store a snapshot of the view data. Then, a procedure that truncates the table, and reloads it based on the current data in the view. Finally, a job that triggers the procedure to start it's work.

Everything else is experimentation.

How to find tags with only certain attributes - BeautifulSoup

You can use lambda functions in findAll as explained in documentation. So that in your case to search for td tag with only valign = "top" use following:

td_tag_list = soup.findAll(
                lambda == "td" and
                len(tag.attrs) == 1 and
                tag["valign"] == "top")

SQlite - Android - Foreign key syntax

You have to define your TASK_CAT column first and then set foreign key on it.

private static final String TASK_TABLE_CREATE = "create table "
        + TASK_TABLE + " (" 
        + TASK_ID + " integer primary key autoincrement, " 
        + TASK_TITLE + " text not null, " 
        + TASK_NOTES + " text not null, "
        + TASK_DATE_TIME + " text not null,"
        + TASK_CAT + " integer,"

More information you can find on sqlite foreign keys doc.

u'\ufeff' in Python string

Here is based on the answer from Mark Tolonen. The string included different languages of the word 'test' that's separated by '|', so you can see the difference.

u = u'ABCtestß???másbêta|test|??????|??|??|???|???????|???????|????????|ki?m tra|Ölçek|'
e8 = u.encode('utf-8')        # encode without BOM
e8s = u.encode('utf-8-sig')   # encode with BOM
e16 = u.encode('utf-16')      # encode with BOM
e16le = u.encode('utf-16le')  # encode without BOM
e16be = u.encode('utf-16be')  # encode without BOM
print('utf-8     %r' % e8)
print('utf-8-sig %r' % e8s)
print('utf-16    %r' % e16)
print('utf-16le  %r' % e16le)
print('utf-16be  %r' % e16be)
print('utf-8  w/ BOM decoded with utf-8     %r' % e8s.decode('utf-8'))
print('utf-8  w/ BOM decoded with utf-8-sig %r' % e8s.decode('utf-8-sig'))
print('utf-16 w/ BOM decoded with utf-16    %r' % e16.decode('utf-16'))
print('utf-16 w/ BOM decoded with utf-16le  %r' % e16.decode('utf-16le'))

Here is a test run:

>>> u = u'ABCtestß???másbêta|test|??????|??|??|???|???????|???????|????????|ki?m tra|Ölçek|'
>>> e8 = u.encode('utf-8')        # encode without BOM
>>> e8s = u.encode('utf-8-sig')   # encode with BOM
>>> e16 = u.encode('utf-16')      # encode with BOM
>>> e16le = u.encode('utf-16le')  # encode without BOM
>>> e16be = u.encode('utf-16be')  # encode without BOM
>>> print('utf-8     %r' % e8)
utf-8     b'ABCtest\xce\xb2\xe8\xb2\x9d\xe5\xa1\x94\xec\x9c\x84m\xc3\xa1sb\xc3\xaata|test|\xd8\xa7\xd8\xae\xd8\xaa\xd8\xa8\xd8\xa7\xd8\xb1|\xe6\xb5\x8b\xe8\xaf\x95|\xe6\xb8\xac\xe8\xa9\xa6|\xe3\x83\x86\xe3\x82\xb9\xe3\x83\x88|\xe0\xa4\xaa\xe0\xa4\xb0\xe0\xa5\x80\xe0\xa4\x95\xe0\xa5\x8d\xe0\xa4\xb7\xe0\xa4\xbe|\xe0\xb4\xaa\xe0\xb4\xb0\xe0\xb4\xbf\xe0\xb4\xb6\xe0\xb5\x8b\xe0\xb4\xa7\xe0\xb4\xa8|\xd7\xa4\xd6\xbc\xd7\xa8\xd7\x95\xd7\x91\xd7\x99\xd7\xa8\xd7\x9f|ki\xe1\xbb\x83m tra|\xc3\x96l\xc3\xa7ek|'
>>> print('utf-8-sig %r' % e8s)
utf-8-sig b'\xef\xbb\xbfABCtest\xce\xb2\xe8\xb2\x9d\xe5\xa1\x94\xec\x9c\x84m\xc3\xa1sb\xc3\xaata|test|\xd8\xa7\xd8\xae\xd8\xaa\xd8\xa8\xd8\xa7\xd8\xb1|\xe6\xb5\x8b\xe8\xaf\x95|\xe6\xb8\xac\xe8\xa9\xa6|\xe3\x83\x86\xe3\x82\xb9\xe3\x83\x88|\xe0\xa4\xaa\xe0\xa4\xb0\xe0\xa5\x80\xe0\xa4\x95\xe0\xa5\x8d\xe0\xa4\xb7\xe0\xa4\xbe|\xe0\xb4\xaa\xe0\xb4\xb0\xe0\xb4\xbf\xe0\xb4\xb6\xe0\xb5\x8b\xe0\xb4\xa7\xe0\xb4\xa8|\xd7\xa4\xd6\xbc\xd7\xa8\xd7\x95\xd7\x91\xd7\x99\xd7\xa8\xd7\x9f|ki\xe1\xbb\x83m tra|\xc3\x96l\xc3\xa7ek|'
>>> print('utf-16    %r' % e16)
utf-16    b"\xff\xfeA\x00B\x00C\x00t\x00e\x00s\x00t\x00\xb2\x03\x9d\x8cTX\x04\xc7m\x00\xe1\x00s\x00b\x00\xea\x00t\x00a\x00|\x00t\x00e\x00s\x00t\x00|\x00'\x06.\x06*\x06(\x06'\x061\x06|\x00Km\xd5\x8b|\x00,nf\x8a|\x00\xc60\xb90\xc80|\x00*\t0\t@\t\x15\tM\t7\t>\t|\x00*\r0\r?\r6\rK\r'\r(\r|\x00\xe4\x05\xbc\x05\xe8\x05\xd5\x05\xd1\x05\xd9\x05\xe8\x05\xdf\x05|\x00k\x00i\x00\xc3\x1em\x00 \x00t\x00r\x00a\x00|\x00\xd6\x00l\x00\xe7\x00e\x00k\x00|\x00"
>>> print('utf-16le  %r' % e16le)
utf-16le  b"A\x00B\x00C\x00t\x00e\x00s\x00t\x00\xb2\x03\x9d\x8cTX\x04\xc7m\x00\xe1\x00s\x00b\x00\xea\x00t\x00a\x00|\x00t\x00e\x00s\x00t\x00|\x00'\x06.\x06*\x06(\x06'\x061\x06|\x00Km\xd5\x8b|\x00,nf\x8a|\x00\xc60\xb90\xc80|\x00*\t0\t@\t\x15\tM\t7\t>\t|\x00*\r0\r?\r6\rK\r'\r(\r|\x00\xe4\x05\xbc\x05\xe8\x05\xd5\x05\xd1\x05\xd9\x05\xe8\x05\xdf\x05|\x00k\x00i\x00\xc3\x1em\x00 \x00t\x00r\x00a\x00|\x00\xd6\x00l\x00\xe7\x00e\x00k\x00|\x00"
>>> print('utf-16be  %r' % e16be)
utf-16be  b"\x00A\x00B\x00C\x00t\x00e\x00s\x00t\x03\xb2\x8c\x9dXT\xc7\x04\x00m\x00\xe1\x00s\x00b\x00\xea\x00t\x00a\x00|\x00t\x00e\x00s\x00t\x00|\x06'\x06.\x06*\x06(\x06'\x061\x00|mK\x8b\xd5\x00|n,\x8af\x00|0\xc60\xb90\xc8\x00|\t*\t0\t@\t\x15\tM\t7\t>\x00|\r*\r0\r?\r6\rK\r'\r(\x00|\x05\xe4\x05\xbc\x05\xe8\x05\xd5\x05\xd1\x05\xd9\x05\xe8\x05\xdf\x00|\x00k\x00i\x1e\xc3\x00m\x00 \x00t\x00r\x00a\x00|\x00\xd6\x00l\x00\xe7\x00e\x00k\x00|"
>>> print()

>>> print('utf-8  w/ BOM decoded with utf-8     %r' % e8s.decode('utf-8'))
utf-8  w/ BOM decoded with utf-8     '\ufeffABCtestß???másbêta|test|??????|??|??|???|???????|???????|????????|ki?m tra|Ölçek|'
>>> print('utf-8  w/ BOM decoded with utf-8-sig %r' % e8s.decode('utf-8-sig'))
utf-8  w/ BOM decoded with utf-8-sig 'ABCtestß???másbêta|test|??????|??|??|???|???????|???????|????????|ki?m tra|Ölçek|'
>>> print('utf-16 w/ BOM decoded with utf-16    %r' % e16.decode('utf-16'))
utf-16 w/ BOM decoded with utf-16    'ABCtestß???másbêta|test|??????|??|??|???|???????|???????|????????|ki?m tra|Ölçek|'
>>> print('utf-16 w/ BOM decoded with utf-16le  %r' % e16.decode('utf-16le'))
utf-16 w/ BOM decoded with utf-16le  '\ufeffABCtestß???másbêta|test|??????|??|??|???|???????|???????|????????|ki?m tra|Ölçek|'

It's worth to know that only both utf-8-sig and utf-16 get back the original string after both encode and decode.

$.ajax - dataType

  • contentType is the HTTP header sent to the server, specifying a particular format.
    Example: I'm sending JSON or XML
  • dataType is you telling jQuery what kind of response to expect.
    Expecting JSON, or XML, or HTML, etc. The default is for jQuery to try and figure it out.

The $.ajax() documentation has full descriptions of these as well.

In your particular case, the first is asking for the response to be in UTF-8, the second doesn't care. Also the first is treating the response as a JavaScript object, the second is going to treat it as a string.

So the first would be:

success: function(data) {
  // get data, e.g. data.title;

The second:

success: function(data) {
  alert("Here's lots of data, just a string: " + data);

npm install error - unable to get local issuer certificate

A disclaimer: This solution is less secure, bad practice, don't do this. I had a duplicate error message--I'm behind a corporate VPN/firewall. I was able to resolve this issue by adding a .typingsrc file to my user directory (C:\Users\MyUserName\.typingsrc in windows). Of course, anytime you're circumventing SSL you should be yapping to your sys admins to fix the certificate issue.

Change the registry URL from https to http, and as seen in nfiles' answser above, set rejectUnauthorized to false.

.typingsrc (placed in project directory or in user root directory)

     "rejectUnauthorized": false,
     "registryURL": ""

Optionally add your github token (I didn't find success until I had added this too.)

    "rejectUnauthorized": false,
    "registryURL": "",
    "githubToken": "YourGitHubToken"

See instructions for setting up your github token at

Is there a foreach in MATLAB? If so, how does it behave if the underlying data changes?

I think this is what the OP really wants:

array = -1:0.1:10

for i=1:numel(array)

Only allow Numbers in input Tag without Javascript

Of course, you can't fully rely on the client-side (javascript) validation, but that's not a reason to avoid it completely. With or without it, you have to do the server-side validation anyway (since the client can disable javascript). And that's just what you're left with, due to your non-javascript solution constraint.

So, after a submit, if the field value doesn't pass the server-side validation, the client should end up on the very same page, with additional error message specifying the requested value format. You also should provide the value format information beforehands, e.g. as a tool-tip hint (title attribute).

There's most certainly no passive client-side validation mechanism existing in HTML 4 / XHTML.

On the other hand, in HTML 5 you have two options:

  • input of type number:

    <input type="number" min="xxx" max="yyy" title="Format: 3 digits" />

    – only validates the range – if user enters a non-number, an empty value is submitted
    – the field visual is enhanced with increment / decrement controls (browser dependent)

  • the pattern attribute:

    <input type="text" pattern="[0-9]{3}" title="Format: 3 digits" />
    <input type="text" pattern="\d{3}" title="Format: 3 digits" />

    – this gives you a full contorl over the format (anything you can specify by regular expression)
    – no visual difference / enhancement

But here you still rely on browser capabilities, so do a server-side validation in either case.

get the value of "onclick" with jQuery?

$('#google').attr('onclick') + ""

However, Firebug shows that this returns a function 'onclick'. You can call the function later on using the following approach:

(new Function ($('#google').attr('onclick') + ';onclick();'))()

... or use a RegEx to strip the function and get only the statements within it.

How can I update the current line in a C# Windows Console App?

I was doing a search for this to see if the solution I wrote could be optimised for speed. What I wanted was a countdown timer, not just updating the current line. Here's what I came up with. Might be useful to someone

            int sleepTime = 5 * 60;    // 5 minutes

            for (int secondsRemaining = sleepTime; secondsRemaining > 0; secondsRemaining --)
                double minutesPrecise = secondsRemaining / 60;
                double minutesRounded = Math.Round(minutesPrecise, 0);
                int seconds = Convert.ToInt32((minutesRounded * 60) - secondsRemaining);
                Console.Write($"\rProcess will resume in {minutesRounded}:{String.Format("{0:D2}", -seconds)} ");

Git push won't do anything (everything up-to-date)

This happened to me when my SourceTree application crashed during staging. And on the command line, it seemed like the previous git add had been corrupted. If this is the case, try:

git init
git add -A
git commit -m 'Fix bad repo'
git push

On the last command, you might need to set the branch.

git push --all origin master

Bear in mind that this is enough if you haven't done any branching or any of that sort. In that case, make sure you push to the correct branch like git push origin develop.

How to serialize Object to JSON?

Easy way to do it without annotations is to use Gson library

Simple as that:

Gson gson = new Gson();
String json = gson.toJson(listaDePontos);

What is an example of the simplest possible example?

Edit: I feel it's better for anyone to consult the excellent chat example on the Socket.IO getting started page. The API has been quite simplified since I provided this answer. That being said, here is the original answer updated small-small for the newer API.

Just because I feel nice today:


<!doctype html>
        <script src='/'></script>
            var socket = io();

            socket.on('welcome', function(data) {

                // Respond with a message including this clients' id sent from the server
                socket.emit('i am client', {data: 'foo!', id:});
            socket.on('time', function(data) {
            socket.on('error', console.error.bind(console));
            socket.on('message', console.log.bind(console));

            function addMessage(message) {
                var text = document.createTextNode(message),
                    el = document.createElement('li'),
                    messages = document.getElementById('messages');

        <ul id='messages'></ul>


var http = require('http'),
    fs = require('fs'),
    // NEVER use a Sync function except at start-up!
    index = fs.readFileSync(__dirname + '/index.html');

// Send index.html to all requests
var app = http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'text/html'});

// server listens to our app
var io = require('').listen(app);

// Send current time to all connected clients
function sendTime() {
    io.emit('time', { time: new Date().toJSON() });

// Send current time every 10 secs
setInterval(sendTime, 10000);

// Emit welcome message on connection
io.on('connection', function(socket) {
    // Use socket to communicate with this particular client only, sending it it's own id
    socket.emit('welcome', { message: 'Welcome!', id: });

    socket.on('i am client', console.log);


Convert integer into byte array (Java)

Using BigInteger:

private byte[] bigIntToByteArray( final int i ) {
    BigInteger bigInt = BigInteger.valueOf(i);      
    return bigInt.toByteArray();

Using DataOutputStream:

private byte[] intToByteArray ( final int i ) throws IOException {      
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    DataOutputStream dos = new DataOutputStream(bos);
    return bos.toByteArray();

Using ByteBuffer:

public byte[] intToBytes( final int i ) {
    ByteBuffer bb = ByteBuffer.allocate(4); 
    return bb.array();

Angularjs - Pass argument to directive

You can try like below:

app.directive("directive_name", function(){
return {
    template:'<div class="title"><h2>{{title}}</h3></div>',

it sets up a two-way binding between the value of the 'accept' attribute and the parent scope.

And also you can set two way data binding with property: '='

For example, if you want both key and value bound to the local scope you would do:


For more info,

So, if you want to pass an argument from controller to directive, then refer this below fiddle

Hope it helps..

Connection Java-MySql : Public Key Retrieval is not allowed

For DBeaver users:

  1. Right click your connection, choose "Edit Connection"

  2. On the "Connection settings" screen (main screen) click on "Edit Driver Settings"

  3. Click on "Connection properties"

  4. Right click the "user properties" area and choose "Add new property"

  5. Add two properties: "useSSL" and "allowPublicKeyRetrieval"

  6. Set their values to "false" and "true" by double clicking on the "value" column

Webpack "OTS parsing error" loading fonts

As of 2018,

use MiniCssExtractPlugin

for Webpack(> 4.0) will solve this problem.

Using extract-text-webpack-plugin in the accepted answer is NOT recommended for Webpack 4.0+.

How can I pipe stderr, and not stdout?

This will redirect command1 stderr to command2 stdin, while leaving command1 stdout as is.

exec 3>&1
command1 2>&1 >&3 3>&- | command2 3>&-
exec 3>&-

Taken from LDP

Adding item to Dictionary within loop

As per my understanding you want data in dictionary as shown below:

key1: value1-1,value1-2,value1-3....value100-1
key2: value2-1,value2-2,value2-3....value100-2
key3: value3-1,value3-2,value3-2....value100-3

for this you can use list for each dictionary keys:

case_list = {}
for entry in entries_list:
    if key in case_list:
        case_list[key1] = [value]

What does if [ $? -eq 0 ] mean for shell scripts?

$? is the exit status of the most recently-executed command; by convention, 0 means success and anything else indicates failure. That line is testing whether the grep command succeeded.

The grep manpage states:

The exit status is 0 if selected lines are found, and 1 if not found. If an error occurred the exit status is 2. (Note: POSIX error handling code should check for '2' or greater.)

So in this case it's checking whether any ERROR lines were found.

How to set the "Content-Type ... charset" in the request header using a HTML link

This is not possible from HTML on. The closest what you can get is the accept-charset attribute of the <form>. Only MSIE browser adheres that, but even then it is doing it wrong (e.g. CP1252 is actually been used when it says that it has sent ISO-8859-1). Other browsers are fully ignoring it and they are using the charset as specified in the Content-Type header of the response. Setting the character encoding right is basically fully the responsiblity of the server side. The client side should just send it back in the same charset as the server has sent the response in.

To the point, you should really configure the character encoding stuff entirely from the server side on. To overcome the inability to edit URIEncoding attribute, someone here on SO wrote a (complex) filter: Detect the URI encoding automatically in Tomcat. You may find it useful as well (note: I haven't tested it).

Update: Noted should be that the meta tag as given in your question is ignored when the content is been transferred over HTTP. Instead, the HTTP response Content-Type header will be used to determine the content type and character encoding. You can determine the HTTP header with for example Firebug, in the Net panel.

alt text

How do I resolve ClassNotFoundException?

I started having this issue after upgrading the "Java Language Support" plugin from Visual Studio Code from version 0.66.0 to 0.67.0.

Downgrading back allowed me to run the same code without any issue.

Angular2 RC6: '<component> is not a known element'

For future problems. If you think you followed all the good answers and yet, the problem is there.

Try turning the server off and on.

I had the same problem, followed all the steps, couldn't solve it. Turn off, on and it was fixed.

Missing artifact com.sun:tools:jar

Changing 'Installed JREs' under 'Preferences -> Java -> Installed JRE' to JDK home worked for me.

FYI - Am using JDK 1.8.

Remove last character from string. Swift language

The global dropLast() function works on sequences and therefore on Strings:

var expression  = "45+22"
expression = dropLast(expression)  // "45+2"

// in Swift 2.0 (according to cromanelli's comment below)
expression = String(expression.characters.dropLast())

PowerShell : retrieve JSON object by field value

Hows about this:

$json=Get-Content -Raw -Path 'my.json' | Out-String | ConvertFrom-Json
${$ -eq $foo}).value

which would select from json structured

{"SomePathYouKnow":{"TheVariableYourUsingToSelectSomething": "Tada!"}

This is based on this accessing values in powershell SO question . Isn't powershell fabulous!

Kill tomcat service running on any port, Windows

1) Go to (Open) Command Prompt (Press Window + R then type cmd Run this).

2) Run following commands

For all listening ports

netstat -aon | find /i "listening"

Apply port filter

netstat -aon |find /i "listening" |find "8080"

Finally with the PID we can run the following command to kill the process

3) Copy PID from result set

taskkill /F /PID

Ex: taskkill /F /PID 189

Sometimes you need to run Command Prompt with Administrator privileges

Done !!! you can start your service now.

How to remove the focus from a TextBox in WinForms?

Try this one:

First set up tab order.

Then in form load event we can send a tab key press programmatically to application. So that application will give focus to 1st contol in the tab order.

in form load even write this line.


This did work for me.

Cmake doesn't find Boost

One more bit of advice for anyone trying to build CGAL in particular, with statically linked Boost. It is not enough to define Boost_USE_STATIC_LIBS; it gets overridden by the time Boost_DEBUG outputs its value. The thing to do here is to check the "Advanced" checkbox and to enable CGAL_Boost_USE_STATIC_LIBS.

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

Update for mid 2016:

The things are changing so fast that if it's late 2017 this answer might not be up to date anymore!

Beginners can quickly get lost in choice of build tools and workflows, but what's most up to date in 2016 is not using Bower, Grunt or Gulp at all! With help of Webpack you can do everything directly in NPM!

Don't get me wrong people use other workflows and I still use GULP in my legacy project(but slowly moving out of it), but this is how it's done in the best companies and developers working in this workflow make a LOT of money!

Look at this template it's a very up-to-date setup consisting of a mixture of the best and the latest technologies:

  • Webpack
  • NPM as a build tool (no Gulp, Grunt or Bower)
  • React with Redux
  • ESLint
  • the list is long. Go and explore!

Your questions:

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

  • Everything belongs in package.json now

  • Dependencies required for build are in "devDependencies" i.e. npm install require-dir --save-dev (--save-dev updates your package.json by adding an entry to devDependencies)

  • Dependencies required for your application during runtime are in "dependencies" i.e. npm install lodash --save (--save updates your package.json by adding an entry to dependencies)

If that is the case, when should I ever install packages explicitly like that without adding them to the file that manages dependencies (apart from installing command line tools globally)?

Always. Just because of comfort. When you add a flag (--save-dev or --save) the file that manages deps (package.json) gets updated automatically. Don't waste time by editing dependencies in it manually. Shortcut for npm install --save-dev package-name is npm i -D package-name and shortcut for npm install --save package-name is npm i -S package-name

How can I check if character in a string is a letter? (Python)

I found a good way to do this with using a function and basic code. This is a code that accepts a string and counts the number of capital letters, lowercase letters and also 'other'. Other is classed as a space, punctuation mark or even Japanese and Chinese characters.

def check(count):

    lowercase = 0
    uppercase = 0
    other = 0

    low = 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'
    upper = 'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'

    for n in count:
        if n in low:
            lowercase += 1
        elif n in upper:
            uppercase += 1
            other += 1

    print("There are " + str(lowercase) + " lowercase letters.")
    print("There are " + str(uppercase) + " uppercase letters.")
    print("There are " + str(other) + " other elements to this sentence.")

RecyclerView vs. ListView

For list views to have good performance you'll need to implement the holder pattern, and that's easy to mess up especially when you want to populate the list with several different kinds of views.

The RecyclerView bakes this pattern in, making it more difficult to mess up. It's also more flexible, making it easier to handle different layouts, that aren't straight linear, like a grid.

what is .subscribe in angular?

A Subscription is an object that represents a disposable resource, usually the execution of an Observable. A Subscription has one important method, unsubscribe, that takes no argument and just disposes of the resource held by the subscription.

import { interval } from 'rxjs';

const observable = interval(1000);
const subscription = observable.subscribe(a=> console.log(a));

/** This cancels the ongoing Observable execution which
was started by calling subscribe with an Observer.*/


A Subscription essentially just has an unsubscribe() function to release resources or cancel Observable executions.

import { interval } from 'rxjs';

const observable1 = interval(400);
const observable2 = interval(300);

const subscription = observable1.subscribe(x => console.log('first: ' + x));
const childSubscription = observable2.subscribe(x => console.log('second: ' + x));


setTimeout(() => {
// It unsubscribes BOTH subscription and childSubscription
}, 1000);

According to the official documentation, Angular should unsubscribe for you, but apparently, there is a bug.

Purpose of Unions in C and C++

The most common use of union I regularly come across is aliasing.

Consider the following:

union Vector3f
  struct{ float x,y,z ; } ;
  float elts[3];

What does this do? It allows clean, neat access of a Vector3f vec;'s members by either name:

vec.x=vec.y=vec.z=1.f ;

or by integer access into the array

for( int i = 0 ; i < 3 ; i++ )

In some cases, accessing by name is the clearest thing you can do. In other cases, especially when the axis is chosen programmatically, the easier thing to do is to access the axis by numerical index - 0 for x, 1 for y, and 2 for z.

img src SVG changing the styles with CSS

You could set your SVG as a mask. That way setting a background-color would act as your fill color.


<div class="logo"></div>


.logo {
  background-color: red;
  -webkit-mask: url(logo.svg) no-repeat center;
  mask: url(logo.svg) no-repeat center;


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