Programs & Examples On #Css specificity

In CSS, specificity is a measure that determines the strength of a selector. The properties within selectors with the highest specificity get applied, overriding the same properties of selectors with lower specificity, regardless of their position within a stylesheet.

Change icon-bar (?) color in bootstrap

In bootstrap 4.3.1 I can change the background color of the toggler icon to white via the css code.


And in my opinion the so changed icon looks fine as well on light as on dark background.

Correct format specifier for double in printf

%Lf (note the capital L) is the format specifier for long doubles.

For plain doubles, either %e, %E, %f, %g or %G will do.


=INDEX(GoogleFinance("CURRENCY:" & "EUR" & "USD", "price", A2), 2, 2)

where A2 is the cell with a date formatted as date.

Replace "EUR" and "USD" with your currency pair.

Error: Could not find or load main class

Problem is not about your main function. Check out for

javac -d . -cp ./apache-log4j-1.2.16/log4j-1.2.16.jar:./vensim.jar

output and run it.

Insert picture into Excel cell

Now we can add a picture to Excel directly and easely. Just follow these instructions:

  1. Go to the Insert tab.
  2. Click on the Pictures option (it’s in the illustrations group). image1
  3. In the ‘Insert Picture’ dialog box, locate the pictures that you want to insert into a cell in Excel. image2
  4. Click on the Insert button. image3
  5. Re-size the picture/image so that it can fit perfectly within the cell. image4
  6. Place the picture in the cell. A cool way to do this is to first press the ALT key and then move the picture with the mouse. It will snap and arrange itself with the border of the cell as soon it comes close to it.

If you have multiple images, you can select and insert all the images at once (as shown in step 4).

You can also resize images by selecting it and dragging the edges. In the case of logos or product images, you may want to keep the aspect ratio of the image intact. To keep the aspect ratio intact, use the corners of an image to resize it.

When you place an image within a cell using the steps above, it will not stick with the cell in case you resize, filter, or hide the cells. If you want the image to stick to the cell, you need to lock the image to the cell it’s placed n.

To do this, you need to follow the additional steps as shown below.

  1. Right-click on the picture and select Format Picture. image5
  2. In the Format Picture pane, select Size & Properties and with the options in Properties, select ‘Move and size with cells’. image6

Now you can move cells, filter it, or hide it, and the picture will also move/filter/hide.


This answer was taken from this link: Insert Picture into a Cell in Excel.

SQL Server: Examples of PIVOTing String data

With pivot_data as
action, -- grouping column
view_edit -- spreading column
from tbl
select action, [view], [edit]
from   pivot_data
pivot  ( max(view_edit) for view_edit in ([view], [edit]) ) as p;

Using setattr() in python

Suppose you want to give attributes to an instance which was previously not written in code. The setattr() does just that. It takes the instance of the class self and key and value to set.

class Example:
    def __init__(self, **kwargs):
        for key, value in kwargs.items():
            setattr(self, key, value)

Twig ternary operator, Shorthand if-then-else

Support for the extended ternary operator was added in Twig 1.12.0.

  1. If foo echo yes else echo no:

    {{ foo ? 'yes' : 'no' }}
  2. If foo echo it, else echo no:

    {{ foo ?: 'no' }}


    {{ foo ? foo : 'no' }}
  3. If foo echo yes else echo nothing:

    {{ foo ? 'yes' }}


    {{ foo ? 'yes' : '' }}
  4. Returns the value of foo if it is defined and not null, no otherwise:

    {{ foo ?? 'no' }}
  5. Returns the value of foo if it is defined (empty values also count), no otherwise:

    {{ foo|default('no') }}

Open File in Another Directory (Python)

Its a very old question but I think it will help newbies line me who are learning python. If you have Python 3.4 or above, the pathlib library comes with the default distribution.

To use it, you just pass a path or filename into a new Path() object using forward slashes and it handles the rest. To indicate that the path is a raw string, put r in front of the string with your actual path.

For example,

from pathlib import Path

dataFolder = Path(r'D:\Desktop dump\example.txt')

Source: The easy way to deal with file paths on Windows, Mac and Linux

(unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

When to use @QueryParam vs @PathParam

This is what I do.

If there is a scenario to retrieve a record based on id, for example you need to get the details of the employee whose id is 15, then you can have resource with @PathParam.

GET /employee/{id}

If there is a scenario where you need to get the details of all employees but only 10 at a time, you may use query param

GET /employee?start=1&size=10

This says that starting employee id 1 get ten records.

To summarize, use @PathParam for retrieval based on id. User @QueryParam for filter or if you have any fixed list of options that user can pass.

Java HTTPS client certificate authentication

For those of you who simply want to set up a two-way authentication (server and client certificates), a combination of these two links will get you there :

Two-way auth setup:

You don't need to use the openssl config file that they mention; just use

  • $ openssl genrsa -des3 -out ca.key 4096

  • $ openssl req -new -x509 -days 365 -key ca.key -out ca.crt

to generate your own CA certificate, and then generate and sign the server and client keys via:

  • $ openssl genrsa -des3 -out server.key 4096

  • $ openssl req -new -key server.key -out server.csr

  • $ openssl x509 -req -days 365 -in server.csr -CA ca.crt -CAkey ca.key -set_serial 100 -out server.crt


  • $ openssl genrsa -des3 -out client.key 4096

  • $ openssl req -new -key client.key -out client.csr

  • $ openssl x509 -req -days 365 -in client.csr -CA ca.crt -CAkey ca.key -set_serial 101 -out client.crt

For the rest follow the steps in the link. Managing the certificates for Chrome works the same as in the example for firefox that is mentioned.

Next, setup the server via:

Note that you have already created the server .crt and .key so you don't have to do that step anymore.

Using the star sign in grep

This worked for me:

grep ".*${expr}" - with double-quotes, preceded by the dot. Where "expr" is whatever string you need in the end of the line.

Standard unix grep w/out additional switches.

Convert UTC dates to local time in PHP

Here is a straight way to convert the UTC time of the questioner to local time. This is for a stored time in a database etc., i.e. any time. You just have to find the time difference between UTC time and the local time you are interested in and then ajust the stored UTC time adding to it the difference.

$df = "G:i:s";  // Use a simple time format to find the difference
$ts1 = strtotime(date($df));   // Timestamp of current local time
$ts2 = strtotime(gmdate($df)); // Timestamp of current UTC time
$ts3 = $ts1-$ts2;              // Their difference

You can then add this difference to the stored UTC time. (In my place, Athens, the difference is exactly 5:00:00)


$time = time() // Or any other timestamp
$time += $ts3  // Add the difference
$dateInLocal = date("Y-m-d H:i:s", $time);

Counting number of words in a file

The below code supports in Java 8

//Read file into String

String fileContent=new String(Files.readAlBytes(Paths.get("MyFile.txt")),StandardCharacters.UFT_8);

//Keeping these into list of strings by splitting with a delimiter

List<String> words = Arrays.asList(contents.split("\\PL+"));

int count=0;
for(String x: words){
 if(x.length()>1) count++;


How to fast get Hardware-ID in C#?

For more details refer to this link

The following code will give you CPU ID:

namespace required System.Management

var mbs = new ManagementObjectSearcher("Select ProcessorId From Win32_processor");
ManagementObjectCollection mbsList = mbs.Get();
string id = "";
foreach (ManagementObject mo in mbsList)
    id = mo["ProcessorId"].ToString();

For Hard disk ID and motherboard id details refer this-link

To speed up this procedure, make sure you don't use SELECT *, but only select what you really need. Use SELECT * only during development when you try to find out what you need to use, because then the query will take much longer to complete.

How to check if a String contains another String in a case insensitive manner in Java?

String x="abCd";

Disable scrolling on `<input type=number>`

One event listener to rule them all

This is similar to @Simon Perepelitsa's answer in pure js, but a bit simpler, as it puts one event listener on the document element and checks if the focused element is a number input:

document.addEventListener("wheel", function(event){
    if(document.activeElement.type === "number"){

If you want to turn off the value scrolling behaviour on some fields, but not others just do this instead:

document.addEventListener("wheel", function(event){
    if(document.activeElement.type === "number" &&

with this:

<input type="number" class="noscroll"/>

If an input has the noscroll class it wont change on scroll, otherwise everything stays the same.

Test here with JSFiddle

Split a large dataframe into a list of data frames based on common value in column

Stumbled across this answer and I actually wanted BOTH groups (data containing that one user and data containing everything but that one user). Not necessary for the specifics of this post, but I thought I would add in case someone was googling the same issue as me.

df <- data.frame(
     g=rep(factor(LETTERS[1:5]), 25)

test_x = split(df,df$g)[['A']]
test_y = split(df,df$g!='A')[['TRUE']]

Here's what it looks like:

            x          y g
1   1.1362198  1.2969541 A
6   0.5510307 -0.2512449 A
11  0.0321679  0.2358821 A
16  0.4734277 -1.2889081 A
21 -1.2686151  0.2524744 A

> head(test_y)
            x          y g
2 -2.23477293  1.1514810 B
3 -0.46958938 -1.7434205 C
4  0.07365603  0.1111419 D
5 -1.08758355  0.4727281 E
7  0.28448637 -1.5124336 B
8  1.24117504  0.4928257 C

Get the Application Context In Fragment In Android?



to obtain the context in any fragment

replace String with another in java

     String s1 = "HelloSuresh";
     String m = s1.replace("Hello","");

What are the most widely used C++ vector/matrix math/linear algebra libraries, and their cost and benefit tradeoffs?

I found this library quite simple and functional ( These are bare bone vectors implemented via C++ templates. No fancy stuff - just what you need to do with vectors (add, subtract multiply, dot, etc).

Laravel migration default value

Might be a little too late to the party, but hope this helps someone with similar issue.

The reason why your default value doesnt't work is because the migration file sets up the default value in your database (MySQL or PostgreSQL or whatever), and not in your Laravel application.

Let me illustrate with an example.

This line means Laravel is generating a new Book instance, as specified in your model. The new Book object will have properties according to the table associated with the model. Up until this point, nothing is written on the database.

$book = new Book();

Now the following lines are setting up the values of each property of the Book object. Same still, nothing is written on the database yet.

$book->author = 'Test'
$book->title = 'Test'

This line is the one writing to the database. After passing on the object to the database, then the empty fields will be filled by the database (may be default value, may be null, or whatever you specify on your migration file).


And thus, the default value will not pop up before you save it to the database.

But, that is not enough. If you try to access $book->price, it will still be null (or 0, i'm not sure). Saving it is only adding the defaults to the record in the database, and it won't affect the Object you are carrying around.

So, to get the instance with filled-in default values, you have to re-fetch the instance. You may use the


Or, a more sophisticated way by refreshing the instance


And then, the next time you try to access the object, it will be filled with the default values.

How can I loop through a C++ map of maps?

use std::map< std::string, std::map<std::string, std::string> >::const_iterator when map is const.

How to output to the console and file?

Here's a small improvement that to @UltraInstinct's Tee class, modified to be a context manager and also captures any exceptions.

import traceback
import sys

# Context manager that copies stdout and any exceptions to a log file
class Tee(object):
    def __init__(self, filename):
        self.file = open(filename, 'w')
        self.stdout = sys.stdout

    def __enter__(self):
        sys.stdout = self

    def __exit__(self, exc_type, exc_value, tb):
        sys.stdout = self.stdout
        if exc_type is not None:

    def write(self, data):

    def flush(self):

To use the context manager:

with Tee('test.txt'):
    raise Exception("Test")

Get all photos from Instagram which have a specific hashtag with PHP

To get more than 20 you can use a load more button.


<!DOCTYPE html>
  <meta charset="utf-8" />
  <title>Instagram more button example</title>
    Instagram PHP API class @ Github
    article, aside, figure, footer, header, hgroup, 
    menu, nav, section { display: block; }
    ul {
      width: 950px;
    ul > li {
      float: left;
      list-style: none;
      padding: 4px;
    #more {
      bottom: 8px;
      margin-left: 80px;
      position: fixed;
      font-size: 13px;
      font-weight: 700;
      line-height: 20px;
  <script src=""></script>
    $(document).ready(function() {
      $('#more').click(function() {
        var tag   = $(this).data('tag'),
            maxid = $(this).data('maxid');

          type: 'GET',
          url: 'ajax.php',
          data: {
            tag: tag,
            max_id: maxid
          dataType: 'json',
          cache: false,
          success: function(data) {
            // Output data
            $.each(data.images, function(i, src) {
              $('ul#photos').append('<li><img src="' + src + '"></li>');

            // Store new maxid
            $('#more').data('maxid', data.next_id);

   * Instagram PHP API

   require_once 'instagram.class.php';

    // Initialize class with client_id
    // Register at and replace client_id with your own
    $instagram = new Instagram('ENTER CLIENT ID HERE');

    // Get latest photos according to geolocation for Växjö
    // $geo = $instagram->searchMedia(56.8770413, 14.8092744);

    $tag = 'sweden';

    // Get recently tagged media
    $media = $instagram->getTagMedia($tag);

    // Display first results in a <ul>
    echo '<ul id="photos">';

    foreach ($media->data as $data) 
        echo '<li><img src="'.$data->images->thumbnail->url.'"></li>';
    echo '</ul>';

    // Show 'load more' button
    echo '<br><button id="more" data-maxid="'.$media->pagination->next_max_id.'" data-tag="'.$tag.'">Load more ...</button>';



     * Instagram PHP API

     require_once 'instagram.class.php';

      // Initialize class for public requests
      $instagram = new Instagram('ENTER CLIENT ID HERE');

      // Receive AJAX request and create call object
      $tag = $_GET['tag'];
      $maxID = $_GET['max_id'];
      $clientID = $instagram->getApiKey();

      $call = new stdClass;
      $call->pagination->next_max_id = $maxID;
      $call->pagination->next_url = "{$tag}/media/recent?client_id={$clientID}&max_tag_id={$maxID}";

      // Receive new data
      $media = $instagram->getTagMedia($tag,$auth=false,array('max_tag_id'=>$maxID));

      // Collect everything for json output
      $images = array();
      foreach ($media->data as $data) {
        $images[] = $data->images->thumbnail->url;

      echo json_encode(array(
        'next_id' => $media->pagination->next_max_id,
        'images'  => $images


Find the function getTagMedia() and replace with:

public function getTagMedia($name, $auth=false, $params=null) {
    return $this->_makeCall('tags/' . $name . '/media/recent', $auth, $params);

Python CSV error: line contains NULL byte

data_initial = open("staff.csv", "rb")
data = csv.reader((line.replace('\0','') for line in data_initial), delimiter=",")

This works for me.

how to compare two string dates in javascript?

Parse the dates and compare them as you would numbers:

function isLater(str1, str2)
    return new Date(str1) > new Date(str2);

If you need to support other date format consider a library such as date.js.

Could not open a connection to your authentication agent

Also check you remote url. use git@github... instead of https:// proptocol


How to get current user, and how to use User class in MVC5?

If you're coding in an ASP.NET MVC Controller, use

using Microsoft.AspNet.Identity;



Worth mentioning that User.Identity.IsAuthenticated and User.Identity.Name will work without adding the above mentioned using statement. But GetUserId() won't be present without it.

If you're in a class other than a Controller, use


In the default template of MVC 5, user ID is a GUID stored as a string.

No best practice yet, but found some valuable info on extending the user profile:

Error:Execution failed for task ':app:processDebugResources'. > Could not delete folder "" in android studio

I have same issue. When I clean my project and rebuild it then everything works fine.

Build -> Clean Project

Why Git is not allowing me to commit even after configuration?

I had this problem even after setting the config properly. git config

My scenario was issuing git command through supervisor (in Linux). On further debugging, supervisor was not reading the git config from home folder. Hence, I had to set the environment HOME variable in the supervisor config so that it can locate the git config correctly. It's strange that supervisor was not able to locate the git config just from the username configured in supervisor's config (/etc/supervisor/conf.d).

How to use router.navigateByUrl and router.navigate in Angular

router.navigate vs router.navigateByUrl

router.navigate is just a convenience method that wraps router.navigateByUrl, it boils down to:

navigate(commands: any[], extras) {
    return router.navigateByUrl(router.createUrlTree(commands, extras), extras);

As mentioned in other answers router.navigateByUrl will only accept absolute URLs:

// This will work
// This WON'T work even though relativeTo parameter is in the signature
router.navigateByUrl("../22", {relativeTo: route})

All the relative calculations are done by router.createUrlTree and router.navigate. Array syntax is used to treat every array element as a URL modifying "command". E.g. ".." - go up, "path" - go down, {expand: true} - add query param, etc.. You can use it like this:

// create /team/33/user/11
router.navigate(['/team', 33, 'user', 11]);

// assuming the current url is `/team/33/user/11` and the route points to `user/11`

// navigate to /team/33/user/11/details
router.navigate(['details'], {relativeTo: route});

// navigate to /team/33/user/22
router.navigate(['../22'], {relativeTo: route});

// navigate to /team/44/user/22
router.navigate(['../../team/44/user/22'], {relativeTo: route});

That {relativeTo: route} parameter is important as that's what router will use as the root for relative operations.

Get it through your component's constructor:

  // In my-awesome.component.ts:

  constructor(private route: ActivatedRoute, private router: Router) {}
  // Example call
  onNavigateClick() {
    // Navigates to a parent component
    this.router.navigate([..], { relativeTo: this.route })

routerLink directive

Nicest thing about this directive is that it will retrieve the ActivatedRoute for you. Under the hood it's using already familiar:

router.navigateByUrl(router.createUrlTree(commands, { relativeTo: route }), { relativeTo: route });

Following variants will produce identical result:


// if the string parameter is passed it will be wrapped into an array

How do I resolve "Please make sure that the file is accessible and that it is a valid assembly or COM component"?

In my case I had to register the .dll.

To do so, open cmd.exe (the console) with admin rights and type:

regsvr32 "foo.dll"

Mask output of `The following objects are masked from....:` after calling attach() function

You use attach without detach - every time you do it new call to attach masks objects attached before (they contain the same names). Either use detach or do not use attach at all. Nice discussion and tips are here.

Keep-alive header clarification

Where is this info kept ("this connection is between computer A and server F")?

A TCP connection is recognized by source IP and port and destination IP and port. Your OS, all intermediate session-aware devices and the server's OS will recognize the connection by this.

HTTP works with request-response: client connects to server, performs a request and gets a response. Without keep-alive, the connection to an HTTP server is closed after each response. With HTTP keep-alive you keep the underlying TCP connection open until certain criteria are met.

This allows for multiple request-response pairs over a single TCP connection, eliminating some of TCP's relatively slow connection startup.

When The IIS (F) sends keep alive header (or user sends keep-alive) , does it mean that (E,C,B) save a connection

No. Routers don't need to remember sessions. In fact, multiple TCP packets belonging to same TCP session need not all go through same routers - that is for TCP to manage. Routers just choose the best IP path and forward packets. Keep-alive is only for client, server and any other intermediate session-aware devices.

which is only for my session ?

Does it mean that no one else can use that connection

That is the intention of TCP connections: it is an end-to-end connection intended for only those two parties.

If so - does it mean that keep alive-header - reduce the number of overlapped connection users ?

Define "overlapped connections". See HTTP persistent connection for some advantages and disadvantages, such as:

  • Lower CPU and memory usage (because fewer connections are open simultaneously).
  • Enables HTTP pipelining of requests and responses.
  • Reduced network congestion (fewer TCP connections).
  • Reduced latency in subsequent requests (no handshaking).

if so , for how long does the connection is saved to me ? (in other words , if I set keep alive- "keep" till when?)

An typical keep-alive response looks like this:

Keep-Alive: timeout=15, max=100

See Hypertext Transfer Protocol (HTTP) Keep-Alive Header for example (a draft for HTTP/2 where the keep-alive header is explained in greater detail than both 2616 and 2086):

  • A host sets the value of the timeout parameter to the time that the host will allows an idle connection to remain open before it is closed. A connection is idle if no data is sent or received by a host.

  • The max parameter indicates the maximum number of requests that a client will make, or that a server will allow to be made on the persistent connection. Once the specified number of requests and responses have been sent, the host that included the parameter could close the connection.

However, the server is free to close the connection after an arbitrary time or number of requests (just as long as it returns the response to the current request). How this is implemented depends on your HTTP server.

How can I submit a POST form using the <a href="..."> tag?

I use a jQuery script to create "shadow" forms for my POSTable links.

Instead of <a href="/some/action?foo=bar">, I write <a data-post="/some/action" data-var-foo="bar" href="#do_action_foo_bar">. The script makes a hidden form with hidden inputs, and submits it when the link is clicked.

    .each(function() {
        let href = $(this).data("post"); if (!href) return;
        let $form = $("<form></form>").attr({ method:"POST",action:href }).css("display","none")
        let data = $(this).data()
        for (let dat in data) {
            if (dat.startsWith("postVar")) {
                let varname = dat.substring(7).toLowerCase()  // postVarId -> id
                let varval = data[dat]
                $form.append($("<input/>").attr({ type:"hidden",name:varname,value:varval }))
    .click(function(ev) {
        if ($(this).data("postform")) $(this).data("postform").submit(); else console.error("No .postform set in <a data-post>")
<script src=""></script>
<a data-post="/some/action" data-var-foo="bar" href="#do_action_foo_bar">click me</a>

What is the best free SQL GUI for Linux for various DBMS systems

For Oracle, I highly recommend the free Oracle SQL Developer

The doucmentation states it also works with non-oracle databases - i've never tried that feature myself, but I do know that it works really well with Oracle

Why doesn't adding CORS headers to an OPTIONS route allow browsers to access my API?

The simplest approach is install the cors module in your project using:

npm i --save cors

Then in your server file import it using the following:

import cors from 'cors';

Then simply use it as a middleware like this:


Hope this helps!

How to print without newline or space?

python 2.6+:

from __future__ import print_function # needs to be first statement in file
print('.', end='')

python 3:

print('.', end='')

python <= 2.5:

import sys

if extra space is OK after each print, in python 2

print '.',

misleading in python 2 - avoid:

print('.'), # avoid this if you want to remain sane
# this makes it look like print is a function but it is not
# this is the `,` creating a tuple and the parentheses enclose an expression
# to see the problem, try:
print('.', 'x'), # this will print `('.', 'x') `

how to change any data type into a string in python

With str(x). However, every data type can define its own string conversion, so this might not be what you want.

Android ListView selected item stay highlighted

To hold the color of listview item when you press it, include the following line in your listview item layout:


Then define bg_key.xml in drawable folder like this:

<?xml version="1.0" encoding="utf-8" ?>
<selector xmlns:android="">
        android:drawable="@color/default_color" />

Finally, include this in your ListView onClickListener:

listView.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> parent, View view, int position,long arg3) {
        ... // Anything

This way, only one item will be color-selected at any time. You can define your color values in res/values/colors.xml with something like this:

<?xml version="1.0" encoding="utf-8"?>
    <color name="pressed_color">#4d90fe</color>
    <color name="default_color">#ffffff</color>

How can I display a messagebox in ASP.NET?

create a simple JavaScript function having one line of code-"alert("Hello this is an Alert")" and instead on OnClick() ,use OnClientClick() method.

`<html xmlns="">
 <head runat="server">
 <script type="text/javascript" language="javascript">
    function showAlert() {
        alert("Hello this is an Alert")
 <form id="form1" runat="server">
 <asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="showAlert()" />

How to Sort a List<T> by a property in the object

An improved of Roger's version.

The problem with GetDynamicSortProperty is that only get the property names but what happen if in the GridView we use NavigationProperties? it will send an exception, since it finds null.


"Employee.Company.Name; " will crash... since allows only "Name" as a parameter to get its value.

Here's an improved version that allows us to sort by Navigation Properties.

public object GetDynamicSortProperty(object item, string propName)
            string[] prop = propName.Split('.'); 

            //Use reflection to get order type                   
            int i = 0;                    
            while (i < prop.Count())
                item = item.GetType().GetProperty(prop[i]).GetValue(item, null);

            return item;
        catch (Exception ex)
            throw ex;


In Jinja2, how do you test if a variable is undefined?

Consider using default filter if it is what you need. For example:

{% set host = | default( -%}

or use more fallback values with "hardcoded" one at the end like:

{% set connectTimeout = config.stackowerflow.connect.timeout | default(config.stackowerflow.timeout) | default(config.timeout) | default(42) -%}

Can curl make a connection to any TCP ports, not just HTTP/HTTPS?

Since you're using PHP, you will probably need to use the CURLOPT_PORT option, like so:

curl_setopt($ch, CURLOPT_PORT, 11740);

Bear in mind, you may face problems with SELinux:

Unable to make php curl request with port number

How to pipe list of files returned by find command to cat to view all the files

Here is my shot for general use:

grep YOURSTRING `find .`

It will print the file name

Using port number in Windows host file

I managed to achieve this by using Windows included Networking tool netsh.

As Mat points out : The hosts file is for host name resolution only, so a combination of the two did the trick for me.


 |                           <--Link by Hosts File
       |                     <--Link by netsh Utility
       +--> localhost:8081


  • Started my server on localhost:8081
  • Added my "local DNS" in the hosts file as a new line
      • Any free address in the network (127.x.x.x) can be used.
      • Note: I am assuming is not occupied by another service.
      • You can check with netstat -a -n -p TCP | grep "LISTENING"
  • added the following network configuration with netsh command utility
    • netsh interface portproxy add v4tov4 listenport=80 listenaddress= connectport=8081 connectaddress=
  • I can now access the server at

- These commands/file modifications need to be executed with Admin rights

- netsh portproxy needs ipv6 libraries even only to use v4tov4, typically they will also be included by default, otherwise install them using the following command: netsh interface ipv6 install

You can see the entry you have added with the command:

netsh interface portproxy show v4tov4

You can remove the entry with the following command:

netsh interface portproxy delete v4tov4 listenport=80 listenaddress=

Links to Resources:

Regex: Check if string contains at least one digit

I'm surprised nobody has mentioned the simplest version:


This will match any digit. If your regular expression engine is Unicode-aware, this means it will match anything that's defined as a digit in any language, not just the Arabic numerals 0-9.

There's no need to put it in [square brackets] to define it as a character class, as one of the other answers did; \d works fine by itself.

Since it's not anchored with ^ or $, it will match any subset of the string, so if the string contains at least one digit, this will match.

And there's no need for the added complexity of +, since the goal is just to determine whether there's at least one digit. If there's at least one digit, this will match; and it will do so with a minimum of overhead.

Page redirect after certain time PHP

Redirect PHP time programming:


Laravel, sync() - how to sync an array and also pass additional pivot fields?

Add following trait to your project and append it to your model class as a trait. This is helpful, because this adds functionality to use multiple pivots. Probably someone can clean this up a little and improve on it ;)

namespace App\Traits;

trait AppTraits
     * Create pivot array from given values
     * @param array $entities
     * @param array $pivots
     * @return array combined $pivots
    public function combinePivot($entities, $pivots = [])
        // Set array
        $pivotArray = [];
        // Loop through all pivot attributes
        foreach ($pivots as $pivot => $value) {
            // Combine them to pivot array
            $pivotArray += [$pivot => $value];
        // Get the total of arrays we need to fill
        $total = count($entities);
        // Make filler array
        $filler = array_fill(0, $total, $pivotArray);
        // Combine and return filler pivot array with data
        return array_combine($entities, $filler);


namespace App;

use Illuminate\Database\Eloquent\Model;

class Example extends Model
    use Traits\AppTraits;
    // ...


// Get id's
$entities = [1, 2, 3];
// Create pivots
$pivots = [
    'price' => 634,
    'name'  => 'Example name',
// Combine the ids and pivots
$combination = $model->combinePivot($entities, $pivots);
// Sync the combination with the related model / pivot

'dependencies.dependency.version' is missing error, but version is managed in parent

What just worked for was to delete the settings.xml in the .m2 folder: this file was telling the project to look for a versión of spring mvc and web that didn't exist.

How to get the selected radio button’s value?

 <input type=radio name=rdbExampleInfo id=rdbExamples value="select 1">
 <input type=radio name=rdbExampleInfo id=rdbExamples value="select 2">
 <input type=radio name=rdbExampleInfo id=rdbExamples value="select 3">
 <input type=radio name=rdbExampleInfo id=rdbExamples value="select 4"> 

etc then use just




How to input a regex in string.replace?

import os, sys, re, glob

pattern = re.compile(r"\<\[\d\>")
replacementStringMatchesPattern = "<[1>"

for infile in glob.glob(os.path.join(os.getcwd(), '*.txt')):
   for line in reader: 
      retline =  pattern.sub(replacementStringMatchesPattern, "", line)         
      print (retline)

Quick way to clear all selections on a multiselect enabled <select> with jQuery?

In JQuery:

  $("#id option:selected").prop("selected", false);

Get a list of dates between two dates using a function

A few ideas:

If you need the list dates in order to loop through them, you could have a Start Date and Day Count parameters and do a while loop whilst creating the date and using it?

Use C# CLR Stored Procedures and write the code in C#

Do this outside the database in code

What's the difference between a method and a function?

To a first order approximation, a method (in C++ style OO) is another word for a member function, that is a function that is part of a class.

In languages like C/C++ you can have functions which are not members of a class; you don't call a function not associated with a class a method.

Why does an image captured using camera intent gets rotated on some devices on Android?

The selected answer uses the most common method answered to this and similar questions. However, it does not work with both front and back cameras on Samsung. For those looking for a solution which works across both front and back cameras for Samsung and other major manufacturers, this answer by nvhausid is awesome:

For those who don't want to click through, the relevant magic is to use the CameraInfo rather then relying on EXIF.

Bitmap realImage = BitmapFactory.decodeByteArray(data, 0, data.length);
android.hardware.Camera.CameraInfo info = new android.hardware.Camera.CameraInfo();
android.hardware.Camera.getCameraInfo(mCurrentCameraId, info);
Bitmap bitmap = rotate(realImage, info.orientation);

Full code in the link.

Pandas create empty DataFrame with only column names

Are you looking for something like this?

    df = pd.DataFrame(columns=COLUMN_NAMES)

   Index(['A', 'B', 'C', 'D', 'E', 'F', 'G'], dtype='object')

Mockito test a void method throws an exception

The parentheses are poorly placed.

You need to use:

doThrow(new Exception()).when(mockedObject).methodReturningVoid(...);

and NOT use:

doThrow(new Exception()).when(mockedObject.methodReturningVoid(...));

This is explained in the documentation

How to get the 'height' of the screen using jquery

$(window).height();   // returns height of browser viewport
$(document).height(); // returns height of HTML document

As documented here:

AngularJs ReferenceError: $http is not defined

I have gone through the same problem when I was using

    myApp.controller('mainController', ['$scope', function($scope,) {
        //$http was not working in this

I have changed the above code to given below. Remember to include $http(2 times) as given below.

 myApp.controller('mainController', ['$scope','$http', function($scope,$http) {
      //$http is working in this

and It has worked well.

What do parentheses surrounding an object/function/class declaration mean?

The first parentheses are for, if you will, order of operations. The 'result' of the set of parentheses surrounding the function definition is the function itself which, indeed, the second set of parentheses executes.

As to why it's useful, I'm not enough of a JavaScript wizard to have any idea. :P

repository element was not specified in the POM inside distributionManagement element or in -DaltDep loymentRepository=id::layout::url parameter

In your pom.xml you should add distributionManagement configuration to where to deploy.

In the following example I have used file system as the locations.

         <name>Internal repo</name>

you can add another location while deployment by using the following command (but to avoid above error you should have at least 1 repository configured) :

mvn deploy -DaltDeploymentRepository=internal.repo::default::file:///home/thara/testesb/in

How to save CSS changes of Styles panel of Chrome Developer Tools?

Now that Chrome 18 was released last week with the required APIs, I published my chrome extension in the Chrome web store. The extension automatically saves changes in CSS or JS in Developer tools into the local disk. Go check it out.

Eloquent: find() and where() usage laravel

Not Found Exceptions

Sometimes you may wish to throw an exception if a model is not found. This is particularly useful in routes or controllers. The findOrFail and firstOrFail methods will retrieve the first result of the query. However, if no result is found, a Illuminate\Database\Eloquent\ModelNotFoundException will be thrown:

$model = App\Flight::findOrFail(1);

$model = App\Flight::where('legs', '>', 100)->firstOrFail();

If the exception is not caught, a 404 HTTP response is automatically sent back to the user. It is not necessary to write explicit checks to return 404 responses when using these methods:

Route::get('/api/flights/{id}', function ($id) {
    return App\Flight::findOrFail($id);

How do you serve a file for download with AngularJS or Javascript?

Just click the button to download using following code.

in html

<a class="btn" ng-click="saveJSON()" ng-href="{{ url }}">Export to JSON</a>

In controller

$scope.saveJSON = function () {_x000D_
   $scope.toJSON = '';_x000D_
   $scope.toJSON = angular.toJson($;_x000D_
   var blob = new Blob([$scope.toJSON], { type:"application/json;charset=utf-8;" });   _x000D_
   var downloadLink = angular.element('<a></a>');_x000D_
                        downloadLink.attr('download', 'fileName.json');_x000D_

Powershell v3 Invoke-WebRequest HTTPS error

An alternative implementation in pure (without Add-Type of source):

#requires -Version 5
#requires -PSEdition Desktop

class TrustAllCertsPolicy : System.Net.ICertificatePolicy {
    [bool] CheckValidationResult([System.Net.ServicePoint] $a,
                                 [System.Security.Cryptography.X509Certificates.X509Certificate] $b,
                                 [System.Net.WebRequest] $c,
                                 [int] $d) {
        return $true
[System.Net.ServicePointManager]::CertificatePolicy = [TrustAllCertsPolicy]::new()

Cleaning up old remote git branches

First, what is the result of git branch -a on machine B?

Second, you have already deleted heads/devel on origin, so that's why you can't delete it from machine B.


git branch -r -d origin/devel


git remote prune origin


git fetch origin --prune

and feel free to add --dry-run to the end of your git statement to see the result of running it without actually running it.

Docs for git remote prune and git branch.

How to focus on a form input text field on page load using jQuery?

Why is everybody using jQuery for something simple as this.

<body OnLoad="document.myform.mytextfield.focus();">

How can I view live MySQL queries?

Even though an answer has already been accepted, I would like to present what might even be the simplest option:

$ mysqladmin -u bob -p -i 1 processlist

This will print the current queries on your screen every second.

  • -u The mysql user you want to execute the command as
  • -p Prompt for your password (so you don't have to save it in a file or have the command appear in your command history)
  • i The interval in seconds.
  • Use the --verbose flag to show the full process list, displaying the entire query for each process. (Thanks, nmat)

There is a possible downside: fast queries might not show up if they run between the interval that you set up. IE: My interval is set at one second and if there is a query that takes .02 seconds to run and is ran between intervals, you won't see it.

Use this option preferably when you quickly want to check on running queries without having to set up a listener or anything else.

What is the result of % in Python?

Also, there is a useful built-in function called divmod:

divmod(a, b)

Take two (non complex) numbers as arguments and return a pair of numbers consisting of their quotient and remainder when using long division.

Get hostname of current request in node.js Express

If you're talking about an HTTP request, you can find the request host in:

But that relies on an incoming request.

More at

If you're looking for machine/native information, try the process object.

Simulate user input in bash script

Here is a snippet I wrote; to ask for users' password and set it in /etc/passwd. You can manipulate it a little probably to get what you need:

echo -n " Please enter the password for the given user: "
read userPass
useradd $userAcct && echo -e "$userPass\n$userPass\n" | passwd $userAcct > /dev/null 2>&1 && echo " User account has been created." || echo " ERR -- User account creation failed!"

How to make scipy.interpolate give an extrapolated result beyond the input range?

1. Constant extrapolation

You can use interp function from scipy, it extrapolates left and right values as constant beyond the range:

>>> from scipy import interp, arange, exp
>>> x = arange(0,10)
>>> y = exp(-x/3.0)
>>> interp([9,10], x, y)
array([ 0.04978707,  0.04978707])

2. Linear (or other custom) extrapolation

You can write a wrapper around an interpolation function which takes care of linear extrapolation. For example:

from scipy.interpolate import interp1d
from scipy import arange, array, exp

def extrap1d(interpolator):
    xs = interpolator.x
    ys = interpolator.y

    def pointwise(x):
        if x < xs[0]:
            return ys[0]+(x-xs[0])*(ys[1]-ys[0])/(xs[1]-xs[0])
        elif x > xs[-1]:
            return ys[-1]+(x-xs[-1])*(ys[-1]-ys[-2])/(xs[-1]-xs[-2])
            return interpolator(x)

    def ufunclike(xs):
        return array(list(map(pointwise, array(xs))))

    return ufunclike

extrap1d takes an interpolation function and returns a function which can also extrapolate. And you can use it like this:

x = arange(0,10)
y = exp(-x/3.0)
f_i = interp1d(x, y)
f_x = extrap1d(f_i)

print f_x([9,10])


[ 0.04978707  0.03009069]

How can I use random numbers in groovy?

If you want to generate random numbers in range including '0' , use the following while 'max' is the maximum number in the range.

Random rand = new Random()
random_num = rand.nextInt(max+1)

MySQL - SELECT WHERE field IN (subquery) - Extremely slow why?

Rewrite the query into this

SELECT st1.*, st2.relevant_field FROM sometable st1
INNER JOIN sometable st2 ON (st1.relevant_field = st2.relevant_field)
GROUP BY  /* list a unique sometable field here*/

I think st2.relevant_field must be in the select, because otherwise the having clause will give an error, but I'm not 100% sure

Never use IN with a subquery; this is notoriously slow.
Only ever use IN with a fixed list of values.

More tips

  1. If you want to make queries faster, don't do a SELECT * only select the fields that you really need.
  2. Make sure you have an index on relevant_field to speed up the equi-join.
  3. Make sure to group by on the primary key.
  4. If you are on InnoDB and you only select indexed fields (and things are not too complex) than MySQL will resolve your query using only the indexes, speeding things way up.

General solution for 90% of your IN (select queries

Use this code

  SELECT 1 FROM sometable b
  WHERE a.relevant_field = b.relevant_field
  GROUP BY b.relevant_field
  HAVING count(*) > 1) 

What's better at freeing memory with PHP: unset() or $var = null

It works in a different way for variables copied by reference:

$a = 5;
$b = &$a;
unset($b); // just say $b should not point to any variable
print $a; // 5

$a = 5;
$b = &$a;
$b = null; // rewrites value of $b (and $a)
print $a; // nothing, because $a = null

How to check iOS version?

Preferred Approach

In Swift 2.0 Apple added availability checking using a far more convenient syntax (Read more here). Now you can check the OS version with a cleaner syntax:

if #available(iOS 9, *) {
    // Then we are on iOS 9
} else {
    // iOS 8 or earlier

This is the preferred over checking respondsToSelector etc (What's New In Swift). Now the compiler will always warn you if you aren't guarding your code properly.

Pre Swift 2.0

New in iOS 8 is NSProcessInfo allowing for better semantic versioning checks.

Deploying on iOS 8 and greater

For minimum deployment targets of iOS 8.0 or above, use NSProcessInfo operatingSystemVersion or isOperatingSystemAtLeastVersion.

This would yield the following:

let minimumVersion = NSOperatingSystemVersion(majorVersion: 8, minorVersion: 1, patchVersion: 2)
if NSProcessInfo().isOperatingSystemAtLeastVersion(minimumVersion) {
    //current version is >= (8.1.2)
} else {
    //current version is < (8.1.2)

Deploying on iOS 7

For minimum deployment targets of iOS 7.1 or below, use compare with NSStringCompareOptions.NumericSearch on UIDevice systemVersion.

This would yield:

let minimumVersionString = "3.1.3"
let versionComparison = UIDevice.currentDevice(), options: .NumericSearch)
switch versionComparison {
    case .OrderedSame, .OrderedDescending:
        //current version is >= (3.1.3)
    case .OrderedAscending:
        //current version is < (3.1.3)

More reading at NSHipster.

How to configure postgresql for the first time?

The other answers were not completely satisfying to me. Here's what worked for postgresql-9.1 on Xubuntu 12.04.1 LTS.

  1. Connect to the default database with user postgres:

    sudo -u postgres psql template1

  2. Set the password for user postgres, then exit psql (Ctrl-D):

    ALTER USER postgres with encrypted password 'xxxxxxx';

  3. Edit the pg_hba.conf file:

    sudo vim /etc/postgresql/9.1/main/pg_hba.conf

    and change "peer" to "md5" on the line concerning postgres:

    local      all     postgres     peer md5

    To know what version of postgresql you are running, look for the version folder under /etc/postgresql. Also, you can use Nano or other editor instead of VIM.

  4. Restart the database :

    sudo /etc/init.d/postgresql restart

    (Here you can check if it worked with psql -U postgres).

  5. Create a user having the same name as you (to find it, you can type whoami):

    sudo createuser -U postgres -d -e -E -l -P -r -s <my_name>

    The options tell postgresql to create a user that can login, create databases, create new roles, is a superuser, and will have an encrypted password. The really important ones are -P -E, so that you're asked to type the password that will be encrypted, and -d so that you can do a createdb.

    Beware of passwords: it will first ask you twice the new password (for the new user), repeated, and then once the postgres password (the one specified on step 2).

  6. Again, edit the pg_hba.conf file (see step 3 above), and change "peer" to "md5" on the line concerning "all" other users:

    local      all     all     peer md5

  7. Restart (like in step 4), and check that you can login without -U postgres:

    psql template1

    Note that if you do a mere psql, it will fail since it will try to connect you to a default database having the same name as you (i.e. whoami). template1 is the admin database that is here from the start.

  8. Now createdb <dbname> should work.

regular expression to match exactly 5 digits

what is about this? \D(\d{5})\D

This will do on:

f 23 23453 234 2344 2534 hallo33333 "50000"

23453, 33333 50000

How to ignore user's time zone and force Date() use specific time zone

Just another approach

function parseTimestamp(timestampStr) {_x000D_
  return new Date(new Date(timestampStr).getTime() + (new Date(timestampStr).getTimezoneOffset() * 60 * 1000));_x000D_
//Sun Jan 01 2017 12:00:00_x000D_
var timestamp = 1483272000000;_x000D_
date = parseTimestamp(timestamp);_x000D_


Selecting/excluding sets of columns in pandas

In a similar vein, when reading a file, one may wish to exclude columns upfront, rather than wastefully reading unwanted data into memory and later discarding them.

As of pandas 0.20.0, usecols now accepts callables.1 This update allows more flexible options for reading columns:

skipcols = [...]
read_csv(..., usecols=lambda x: x not in skipcols)

The latter pattern is essentially the inverse of the traditional usecols method - only specified columns are skipped.


Data in a file

import numpy as np
import pandas as pd

df = pd.DataFrame(np.random.randn(100, 4), columns=list('ABCD'))

filename = "foo.csv"


skipcols = ["B", "D"]
df1 = pd.read_csv(filename, usecols=lambda x: x not in skipcols, index_col=0)


          A         C
0  0.062350  0.076924
1 -0.016872  1.091446
2  0.213050  1.646109
3 -1.196928  1.153497
4 -0.628839 -0.856529


A DataFrame was written to a file. It was then read back as a separate DataFrame, now skipping unwanted columns (B and D).

Note that for the OP's situation, since data is already created, the better approach is the accepted answer, which drops unwanted columns from an extant object. However, the technique presented here is most useful when directly reading data from files into a DataFrame.

A request was raised for a "skipcols" option in this issue and was addressed in a later issue.

How to disable phone number linking in Mobile Safari?

My experience is the same as some others mentioned. The meta tag...

<meta name = "format-detection" content = "telephone=no"> when the website is running in Mobile Safari (i.e., with chrome) but stops working when run as a webapp (i.e., is saved to home screen and runs without chrome).

My less-than-ideal solution is to insert the values into input fields...

<input type="text" readonly="readonly" style="border:none;" value="3105551212">

It's less than ideal because, despite the border being set to none, iOS renders a multi-pixel gray bar above the field. But, it's better than seeing the number as a link.

Increasing the maximum post size

There are 2 different places you can set it:



.htaccess / httpd.conf / virtualhost include

php_value post_max_size 20M
php_value upload_max_filesize 20M

Which one to use depends on what you have access to.

.htaccess will not require a server restart, but php.ini and the other apache conf files will.

What is the difference between ManualResetEvent and AutoResetEvent in .NET?

OK, normally it does not a good practice to add 2 answers in same thread, but I did not want to edit/delete my previous answer, since it can help on another manner.

Now, I created, much more comprehensive, and easy to understand, run-to-learn console app snippet below.

Just run the examples on two different consoles, and observe behaviour. You will get much more clear idea there what is happening behind the scenes.

Manual Reset Event

using System;
using System.Threading;

namespace ConsoleApplicationDotNetBasics.ThreadingExamples
    public class ManualResetEventSample
        private readonly ManualResetEvent _manualReset = new ManualResetEvent(false);

        public void RunAll()
            new Thread(Worker1).Start();
            new Thread(Worker2).Start();
            new Thread(Worker3).Start();
            Console.WriteLine("All Threads Scheduled to RUN!. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
            Console.WriteLine("Main Thread is waiting for 15 seconds, observe 3 thread behaviour. All threads run once and stopped. Why? Because they call WaitOne() internally. They will wait until signals arrive, down below.");
            Console.WriteLine("1- Main will call ManualResetEvent.Set() in 5 seconds, watch out!");
            Console.WriteLine("2- Main will call ManualResetEvent.Set() in 5 seconds, watch out!");
            Console.WriteLine("3- Main will call ManualResetEvent.Set() in 5 seconds, watch out!");
            Console.WriteLine("4- Main will call ManualResetEvent.Reset() in 5 seconds, watch out!");
            Console.WriteLine("It ran one more time. Why? Even Reset Sets the state of the event to nonsignaled (false), causing threads to block, this will initial the state, and threads will run again until they WaitOne().");
            Console.WriteLine("This will go so on. Everytime you call Set(), ManualResetEvent will let ALL threads to run. So if you want synchronization between them, consider using AutoReset event, or simply user TPL (Task Parallel Library).");
            Console.WriteLine("Main thread reached to end! ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);


        public void Worker1()
            for (int i = 1; i <= 10; i++)
                Console.WriteLine("Worker1 is running {0}/10. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
                // this gets blocked until _autoReset gets signal
            Console.WriteLine("Worker1 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
        public void Worker2()
            for (int i = 1; i <= 10; i++)
                Console.WriteLine("Worker2 is running {0}/10. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
                // this gets blocked until _autoReset gets signal
            Console.WriteLine("Worker2 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
        public void Worker3()
            for (int i = 1; i <= 10; i++)
                Console.WriteLine("Worker3 is running {0}/10. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
                // this gets blocked until _autoReset gets signal
            Console.WriteLine("Worker3 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);


Manual Reset Event Output

Auto Reset Event

using System;
using System.Threading;

namespace ConsoleApplicationDotNetBasics.ThreadingExamples
    public class AutoResetEventSample
        private readonly AutoResetEvent _autoReset = new AutoResetEvent(false);

        public void RunAll()
            new Thread(Worker1).Start();
            new Thread(Worker2).Start();
            new Thread(Worker3).Start();
            Console.WriteLine("All Threads Scheduled to RUN!. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
            Console.WriteLine("Main Thread is waiting for 15 seconds, observe 3 thread behaviour. All threads run once and stopped. Why? Because they call WaitOne() internally. They will wait until signals arrive, down below.");
            Console.WriteLine("1- Main will call AutoResetEvent.Set() in 5 seconds, watch out!");
            Console.WriteLine("2- Main will call AutoResetEvent.Set() in 5 seconds, watch out!");
            Console.WriteLine("3- Main will call AutoResetEvent.Set() in 5 seconds, watch out!");
            Console.WriteLine("4- Main will call AutoResetEvent.Reset() in 5 seconds, watch out!");
            Console.WriteLine("Nothing happened. Why? Becasuse Reset Sets the state of the event to nonsignaled, causing threads to block. Since they are already blocked, it will not affect anything.");
            Console.WriteLine("This will go so on. Everytime you call Set(), AutoResetEvent will let another thread to run. It will make it automatically, so you do not need to worry about thread running order, unless you want it manually!");
            Console.WriteLine("Main thread reached to end! ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);


        public void Worker1()
            for (int i = 1; i <= 5; i++)
                Console.WriteLine("Worker1 is running {0}/5. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
                // this gets blocked until _autoReset gets signal
            Console.WriteLine("Worker1 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
        public void Worker2()
            for (int i = 1; i <= 5; i++)
                Console.WriteLine("Worker2 is running {0}/5. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
                // this gets blocked until _autoReset gets signal
            Console.WriteLine("Worker2 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);
        public void Worker3()
            for (int i = 1; i <= 5; i++)
                Console.WriteLine("Worker3 is running {0}/5. ThreadId: {1}.", i, Thread.CurrentThread.ManagedThreadId);
                // this gets blocked until _autoReset gets signal
            Console.WriteLine("Worker3 is DONE. ThreadId: {0}", Thread.CurrentThread.ManagedThreadId);


Auto Reset Event Output

How can I quickly and easily convert spreadsheet data to JSON?

Assuming you really mean easiest and are not necessarily looking for a way to do this programmatically, you can do this:

  1. Add, if not already there, a row of "column Musicians" to the spreadsheet. That is, if you have data in columns such as:

    Rory Gallagher      Guitar
    Gerry McAvoy        Bass
    Rod de'Ath          Drums
    Lou Martin          Keyboards
    Donkey Kong Sioux   Self-Appointed Semi-official Stomper

    Note: you might want to add "Musician" and "Instrument" in row 0 (you might have to insert a row there)

  2. Save the file as a CSV file.

  3. Copy the contents of the CSV file to the clipboard

  4. Go to

  5. Verify that the "First row is column names" checkbox is checked

  6. Paste the CSV data into the content area

  7. Mash the "Convert CSV to JSON" button

    With the data shown above, you will now have:

        "MUSICIAN":"Rory Gallagher",
        "MUSICIAN":"Gerry McAvoy",
        "MUSICIAN":"Rod D'Ath",
        "MUSICIAN":"Lou Martin",
        "MUSICIAN":"Donkey Kong Sioux",
        "INSTRUMENT":"Self-Appointed Semi-Official Stomper"

    With this simple/minimalistic data, it's probably not required, but with large sets of data, it can save you time and headache in the proverbial long run by checking this data for aberrations and abnormalcy.

  8. Go here:

  9. Paste the JSON into the content area

  10. Pres the "Validate" button.

If the JSON is good, you will see a "Valid JSON" remark in the Results section below; if not, it will tell you where the problem[s] lie so that you can fix it/them.

Magento Product Attribute Get Value

This one works-

echo $_product->getData('ATTRIBUTE_NAME_HERE');

Error in : figure margins too large in R

I had this error when I was trying to plot high dimensional data. If that's what is going on with you, try multidimensional scaling:

Windows could not start the Apache2 on Local Computer - problem

Follow this step it will works fine. Go to Control panel-->Programs and features-->click Turn Windows features on and off--> see IIS is Checked Or Not If checked please unckeck IIS and restart the computer.After that Open services see Web Deployement Agent Service status if its started please stop.And also see WampAppache and WampSqlID if its not started please start manually. it will works for me.

Changing navigation title programmatically

Swift 5.1

// Set NavigationBar Title Programmatically and Dynamic

Note : First add NavigationControllerItem to Your ViewController then goto their ViewController.swift file and Just Copy and Paste this in viewDidLoad().

navigationItem.title = "Your Title Here"

Calculate number of hours between 2 dates in PHP

your answer is:

round((strtotime($day2) - strtotime($day1))/(60*60))

Twitter Bootstrap 3: how to use media queries?

Use media queries for IE;

@media only screen 
and (min-device-width : 320px) 
and (max-device-width : 480px) 
and (orientation : landscape) and (-ms-high-contrast: none), (-ms-high-contrast: active) {
@media only screen 
and (min-device-width : 360px) 
and (max-device-width : 640px) 
and (orientation : portrait) and (-ms-high-contrast: none), (-ms-high-contrast: active) {

Copy a file list as text from Windows Explorer

In Windows 7 and later, this will do the trick for you

  • Select the file/files.
  • Hold the shift key and then right-click on the selected file/files.
  • You will see Copy as Path. Click that.
  • Open a Notepad file and paste and you will be good to go.

The menu item Copy as Path is not available in Windows XP.

How to Lazy Load div background images

I know it's not related to the image load but here what I did in one of the job interview test.


<div id="news-feed">Scroll to see News (Newest First)</div>


article {
   margin-top: 500px;
   opacity: 0;
   border: 2px solid #864488;
   padding: 5px 10px 10px 5px;
   background-image: -webkit-gradient(
   left top,
   left bottom,
   color-stop(0, #DCD3E8),
   color-stop(1, #BCA3CC)
   background-image: -o-linear-gradient(bottom, #DCD3E8 0%, #BCA3CC 100%);
   background-image: -moz-linear-gradient(bottom, #DCD3E8 0%, #BCA3CC 100%);
   background-image: -webkit-linear-gradient(bottom, #DCD3E8 0%, #BCA3CC 100%);
   background-image: -ms-linear-gradient(bottom, #DCD3E8 0%, #BCA3CC 100%);
   background-image: linear-gradient(to bottom, #DCD3E8 0%, #BCA3CC 100%);
   color: gray;
   font-family: arial;    

article h4 {
   font-family: "Times New Roman";
   margin: 5px 1px;

.main-news {
   border: 5px double gray;
   padding: 15px;


var newsData,
    SortData = '',
    i = 1;

$.getJSON("", function(data) {

   newsData =;

   function SortByDate(x,y) {
     return ((x.published == y.published) ? 0 : ((x.published < y.published) ? 1 : -1 ));

   var sortedNewsData = newsData.sort(SortByDate);

   $.each( sortedNewsData, function( key, val ) {
     SortData += '<article id="article' + i + '"><h4>Published on: ' + val.published + '</h4><div  class="main-news">' + val.title + '</div></article>';


$(window).scroll(function() {

   var $window = $(window),
       wH = $window.height(),
       wS = $window.scrollTop() + 1

   for (var j=0; j<$('article').length;j++) {
      var eT = $('#article' + j ).offset().top,
          eH = $('#article' + j ).outerHeight();

          if (wS > ((eT + eH) - (wH))) {
             $('#article' + j ).animate({'opacity': '1'}, 500);


I am sorting the data by Date and then doing lazy load on window scroll function.

I hope it helps :)


Android – Listen For Incoming SMS Messages

Thank to @Vineet Shukla (the accepted answer) and @Ruchir Baronia (found the issue in the accepted answer), below is the Kotlin version:

Add permission:

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

Register BroadcastReceiver in AndroidManifest:

    <intent-filter android:priority="2332412">
        <action android:name="android.provider.Telephony.SMS_RECEIVED" />

Add implementation for BroadcastReceiver:

class SmsReceiver : BroadcastReceiver() {
    private var mLastTimeReceived = System.currentTimeMillis()

    override fun onReceive(p0: Context?, intent: Intent?) {
        val currentTimeMillis = System.currentTimeMillis()
        if (currentTimeMillis - mLastTimeReceived > 200) {
            mLastTimeReceived = currentTimeMillis

            val pdus: Array<*>
            val msgs: Array<SmsMessage?>
            var msgFrom: String?
            var msgText: String?
            val strBuilder = StringBuilder()
            intent?.extras?.let {
                try {
                    pdus = it.get("pdus") as Array<*>
                    msgs = arrayOfNulls(pdus.size)
                    for (i in msgs.indices) {
                        msgs[i] = SmsMessage.createFromPdu(pdus[i] as ByteArray)

                    msgText = strBuilder.toString()
                    msgFrom = msgs[0]?.originatingAddress

                    if (!msgFrom.isNullOrBlank() && !msgText.isNullOrBlank()) {
                        // Do some thing here
                } catch (e: Exception) {

Sometime event fires twice so I add mLastTimeReceived = System.currentTimeMillis()

Inserting HTML elements with JavaScript

In old school JavaScript, you could do this:

document.body.innerHTML = '<p id="foo">Some HTML</p>' + document.body.innerHTML;

In response to your comment:

[...] I was interested in declaring the source of a new element's attributes and events, not the innerHTML of an element.

You need to inject the new HTML into the DOM, though; that's why innerHTML is used in the old school JavaScript example. The innerHTML of the BODY element is prepended with the new HTML. We're not really touching the existing HTML inside the BODY.

I'll rewrite the abovementioned example to clarify this:

var newElement = '<p id="foo">This is some dynamically added HTML. Yay!</p>';
var bodyElement = document.body;
bodyElement.innerHTML = newElement + bodyElement.innerHTML;
// note that += cannot be used here; this would result in 'NaN'

Using a JavaScript framework would make this code much less verbose and improve readability. For example, jQuery allows you to do the following:

$('body').prepend('<p id="foo">Some HTML</p>');

How to Troubleshoot Intermittent SQL Timeout Errors

We experienced this with SQL Server 2012 / SP3, when running a query via an SqlCommand object from within a C# application. The Command was a simple invocation of a stored procedure having one table parameter; we were passing a list of about 300 integers. The procedure in turn called three user-defined functions and passed the table as a parameter to each of them. The CommandTimeout was set to 90 seconds.

When running precisely the same stored proc with the same argument from within SQL Server Management Studio, the query ran in 15 seconds. But when running it from our application using the above setup, the SqlCommand timed out. The same SqlCommand (with different but comparable data) had been running successfully for weeks, but now it failed with any table argument containing more than 20 or so integers. We did a trace and discovered that when run from the SqlCommand object, the database spent the entire 90 seconds acquiring locks, and would invoke the procedure only at about the moment of the timeout. We changed the CommandTimeout time, and no matter time what we selected the stored proc would be invoked only at the very end of that period. So we surmise that SQL Server was indefinitely acquiring the same locks over and over, and that only the timeout of the Command object caused SQL Server to stop its infinite loop and begin executing the query, by which time it was too late to succeed. A simulation of this same process on a similar server using similar data exhibited no such problem. Our solution was to reboot the entire database server, after which the problem disappeared.

So it appears that there is some problem in SQL Server wherein some resource gets cumulatively consumed and never released. Eventually when connecting via an SqlConnection and running an SqlCommand involving a table parameter, SQL Server goes into an infinite loop acquiring locks. The loop is terminated by the timeout of the SqlCommand object. The solution is to reboot, apparently restoring (temporary?) sanity to SQL Server.

Java Singleton and Synchronization

Enum singleton

The simplest way to implement a Singleton that is thread-safe is using an Enum

public enum SingletonEnum {
  public void doSomething(){
    System.out.println("This is a singleton");

This code works since the introduction of Enum in Java 1.5

Double checked locking

If you want to code a “classic” singleton that works in a multithreaded environment (starting from Java 1.5) you should use this one.

public class Singleton {

  private static volatile Singleton instance = null;

  private Singleton() {

  public static Singleton getInstance() {
    if (instance == null) {
      synchronized (Singleton.class){
        if (instance == null) {
          instance = new Singleton();
    return instance ;

This is not thread-safe before 1.5 because the implementation of the volatile keyword was different.

Early loading Singleton (works even before Java 1.5)

This implementation instantiates the singleton when the class is loaded and provides thread safety.

public class Singleton {

  private static final Singleton instance = new Singleton();

  private Singleton() {

  public static Singleton getInstance() {
    return instance;

  public void doSomething(){
    System.out.println("This is a singleton");


Using two values for one switch case statement

With the integration of JEP 325: Switch Expressions (Preview) in JDK-12 early access builds, one can now make use of the new form of the switch label as :-

case text1, text4 -> {

or to rephrase the demo from one of the answers, something like :-

public class RephraseDemo {

    public static void main(String[] args) {
        int month = 9;
        int year = 2018;
        int numDays = 0;

        switch (month) {
            case 1, 3, 5, 7, 8, 10, 12 ->{
                numDays = 31;
            case 4, 6, 9, 11 ->{
                numDays = 30;
            case 2 ->{
                if (((year % 4 == 0) &&
                        !(year % 100 == 0))
                        || (year % 400 == 0))
                    numDays = 29;
                    numDays = 28;
            default ->{
                System.out.println("Invalid month.");

        System.out.println("Number of Days = " + numDays);

Here is how you can give it a try - Compile a JDK12 preview feature with Maven

getting the reason why websockets closed with close code 1006

Thought this might be handy for others. Knowing regex is useful, kids. Stay in school.

Edit: Turned it into a handy dandy function!

let specificStatusCodeMappings = {
    '1000': 'Normal Closure',
    '1001': 'Going Away',
    '1002': 'Protocol Error',
    '1003': 'Unsupported Data',
    '1004': '(For future)',
    '1005': 'No Status Received',
    '1006': 'Abnormal Closure',
    '1007': 'Invalid frame payload data',
    '1008': 'Policy Violation',
    '1009': 'Message too big',
    '1010': 'Missing Extension',
    '1011': 'Internal Error',
    '1012': 'Service Restart',
    '1013': 'Try Again Later',
    '1014': 'Bad Gateway',
    '1015': 'TLS Handshake'

function getStatusCodeString(code) {
    if (code >= 0 && code <= 999) {
        return '(Unused)';
    } else if (code >= 1016) {
        if (code <= 1999) {
            return '(For WebSocket standard)';
        } else if (code <= 2999) {
            return '(For WebSocket extensions)';
        } else if (code <= 3999) {
            return '(For libraries and frameworks)';
        } else if (code <= 4999) {
            return '(For applications)';
    if (typeof(specificStatusCodeMappings[code]) !== 'undefined') {
        return specificStatusCodeMappings[code];
    return '(Unknown)';


getStatusCodeString(1006); //'Abnormal Closure'

    '0-999': '(Unused)',
    '1016-1999': '(For WebSocket standard)',
    '2000-2999': '(For WebSocket extensions)',
    '3000-3999': '(For libraries and frameworks)',
    '4000-4999': '(For applications)'

    '1000': 'Normal Closure',
    '1001': 'Going Away',
    '1002': 'Protocol Error',
    '1003': 'Unsupported Data',
    '1004': '(For future)',
    '1005': 'No Status Received',
    '1006': 'Abnormal Closure',
    '1007': 'Invalid frame payload data',
    '1008': 'Policy Violation',
    '1009': 'Message too big',
    '1010': 'Missing Extension',
    '1011': 'Internal Error',
    '1012': 'Service Restart',
    '1013': 'Try Again Later',
    '1014': 'Bad Gateway',
    '1015': 'TLS Handshake'

Source (with minor edits for terseness):

How to set session timeout in web.config

If you are using MVC, you put this in the web.config file in the Root directory of the web application, not the web.config in the Views directory. It also needs to be IN the system.web node, not under like George2 stated in his question: "I wrote under system.web section in the web.config"

The timeout parameter value represents minutes.

There are other attributes that can be set in the sessionState element. You can find information here: sessionState

      <sessionState timeout="20"></sessionState>

You can then catch the begining of a new session in the Global.asax file by adding the following method:

void Session_Start(object sender, EventArgs e)
    if (Session.IsNewSession)
        //do things that need to happen
        //when a new session starts.

Lookup City and State by Zip Google Geocode Api

couple of months back, I had the same requirement for one of my projects. I searched a bit for it and found out the following solution. This is not the only solution but I found it to one of the simpler one.

Use the webservice at
Specifically GetInfoByZIP() method.

You will be able to query by any zipcode (ex: 40220) and you will have a response back as the following...

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

Hope this helps...

How to make parent wait for all child processes to finish?

pid_t child_pid, wpid;
int status = 0;

//Father code (before child processes start)

for (int id=0; id<n; id++) {
    if ((child_pid = fork()) == 0) {
        //child code

while ((wpid = wait(&status)) > 0); // this way, the father waits for all the child processes 

//Father code (After all child processes end)

wait waits for a child process to terminate, and returns that child process's pid. On error (eg when there are no child processes), -1 is returned. So, basically, the code keeps waiting for child processes to finish, until the waiting errors out, and then you know they are all finished.

How to calculate age in T-SQL with years, months, and days

declare @StartDate datetime = '2016-01-31'
declare @EndDate datetime = '2016-02-01'
SELECT @StartDate AS [StartDate]
      ,@EndDate AS [EndDate]
      ,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END AS [Years]
      ,DATEDIFF(Month,(DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate)),@EndDate) - CASE WHEN DATEADD(Month, DATEDIFF(Month,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate),@EndDate) , @StartDate) > @EndDate THEN 1 ELSE 0 END AS [Months]
      ,DATEDIFF(Day, DATEADD(Month,DATEDIFF(Month, (DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate)),@EndDate) - CASE WHEN DATEADD(Month, DATEDIFF(Month,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate),@EndDate) , @StartDate) > @EndDate THEN 1 ELSE 0 END  ,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate)) ,@EndDate) - CASE WHEN DATEADD(Day,DATEDIFF(Day, DATEADD(Month,DATEDIFF(Month, (DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate)),@EndDate) - CASE WHEN DATEADD(Month, DATEDIFF(Month,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate),@EndDate) , @StartDate) > @EndDate THEN 1 ELSE 0 END  ,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate)) ,@EndDate),DATEADD(Month,DATEDIFF(Month, (DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate)),@EndDate) - CASE WHEN DATEADD(Month, DATEDIFF(Month,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate),@EndDate) , @StartDate) > @EndDate THEN 1 ELSE 0 END  ,DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate) - CASE WHEN DATEADD(Year,DATEDIFF(Year,@StartDate,@EndDate), @StartDate) > @EndDate THEN 1 ELSE 0 END,@StartDate))) > @EndDate THEN 1 ELSE 0 END AS [Days]

How to convert a HTMLElement to a string

The most easy way to do is copy innerHTML of that element to tmp variable and make it empty, then append new element, and after that copy back tmp variable to it. Here is an example I used to add jquery script to top of head.

var imported = document.createElement('script');
imported.src = '';
var tmpHead = document.head.innerHTML;
document.head.innerHTML = "";
document.head.innerHTML += tmpHead;

That simple :)

Show percent % instead of counts in charts of categorical variables

Since this was answered there have been some meaningful changes to the ggplot syntax. Summing up the discussion in the comments above:


 p <- ggplot(mydataf, aes(x = foo)) +  
        geom_bar(aes(y = (..count..)/sum(..count..))) + 
        ## version 3.0.0

Here's a reproducible example using mtcars:

 ggplot(mtcars, aes(x = factor(hp))) +  
        geom_bar(aes(y = (..count..)/sum(..count..))) + 
        scale_y_continuous(labels = percent) ## version 3.0.0

enter image description here

This question is currently the #1 hit on google for 'ggplot count vs percentage histogram' so hopefully this helps distill all the information currently housed in comments on the accepted answer.

Remark: If hp is not set as a factor, ggplot returns:

enter image description here

How to center a button within a div?

et voila:

button {
  width: 100px; // whatever your button's width
  margin: 0 auto; // auto left/right margins
  display: block;

Update: If OP is looking for horizontal and vertical centre, this answer will do it for a fixed width/height element.

Android Studio: Default project directory

Top of The Android Studio Title bar its shows the complete file path or LocationLook this image

jQuery or Javascript - how to disable window scroll without overflow:hidden;

If you want to scroll the element you're over and prevent the window to scroll, here's a really useful function :

$('.Scrollable').on('DOMMouseScroll mousewheel', function(ev) {
    var $this = $(this),
        scrollTop = this.scrollTop,
        scrollHeight = this.scrollHeight,
        height = $this.height(),
        delta = (ev.type == 'DOMMouseScroll' ?
            ev.originalEvent.detail * -40 :
        up = delta > 0;

    var prevent = function() {
        ev.returnValue = false;
        return false;

    if (!up && -delta > scrollHeight - height - scrollTop) {
        // Scrolling down, but this will take us past the bottom.

        return prevent();
    } else if (up && delta > scrollTop) {
        // Scrolling up, but this will take us past the top.
        return prevent();

Apply the class "Scrollable" to your element and that's it!

get current page from url

Path.GetFileName( Request.Url.AbsolutePath )

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

I have just compile it and it compiles fine without the implicit import, probably you're seeing a stale cache or something of your IDE.

Have you tried compiling from the command line?

I have the exact same version:

here it is

Probably you're thinking the warning is an error.


It looks like you have a Arrays.class file in the directory where you're trying to compile ( probably created before ). That's why the explicit import solves the problem. Try copying your source code to a clean new directory and try again. You'll see there is no error this time. Or, clean up your working directory and remove the Arrays.class

How to change content on hover

The CSS content property along with ::after and ::before pseudo-elements have been introduced for this.

.item:hover a{
    content: 'ADD';

JSFiddle Demo

How to convert URL parameters to a JavaScript object?

I had the same problem, tried the solutions here, but none of them really worked, since I had arrays in the URL parameters, like this:


So I ended up writing my own JS function, which makes an array out of the param in URI:

 * Creates an object from URL encoded data
var createObjFromURI = function() {
    var uri = decodeURI(;
    var chunks = uri.split('&');
    var params = Object();

    for (var i=0; i < chunks.length ; i++) {
        var chunk = chunks[i].split('=');
        if(chunk[0].search("\\[\\]") !== -1) {
            if( typeof params[chunk[0]] === 'undefined' ) {
                params[chunk[0]] = [chunk[1]];

            } else {

        } else {
            params[chunk[0]] = chunk[1];

    return params;

Using Intent in an Android application to show another activity

Use this code:

Intent intent=new Intent(context,SecondActivty.class);

context: refer to current activity context,

please make sure that you have added activity in android manifest file.

Following code for adding activity in android manifest file

<Activity name=".SecondActivity">

Update TextView Every Second

Extending @endian 's answer, you could use a thread and call a method to update the TextView. Below is some code I made up on the spot.

java.util.Date noteTS;
String time, date;
TextView tvTime, tvDate;

protected void onCreate(Bundle savedInstanceState) {

    tvTime = (TextView) findViewById(;
    tvDate = (TextView) findViewById(;

    Thread t = new Thread() {

        public void run() {
            try {
                while (!isInterrupted()) {
                    runOnUiThread(new Runnable() {
                        public void run() {
            } catch (InterruptedException e) {


private void updateTextView() {
    noteTS = Calendar.getInstance().getTime();

    String time = "hh:mm"; // 12:00
    tvTime.setText(DateFormat.format(time, noteTS));

    String date = "dd MMMMM yyyy"; // 01 January 2013
    tvDate.setText(DateFormat.format(date, noteTS));

How do I search for names with apostrophe in SQL Server?

Double them to escape;

  FROM Header
 WHERE userID LIKE '%''%'

How to convert R Markdown to PDF?

Only two steps:

  1. Install the latest release "pandoc" from here:

  2. Call the function pandoc in the library(knitr)

    pandoc('', format = 'latex')

Thus, you can convert your "" into "input.pdf".

how do I change text in a label with swift?

use a simple formula: WHO.WHAT = VALUE


WHO is the element in the storyboard you want to make changes to for eg. label

WHAT is the property of that element you wish to change for eg. text

VALUE is the change that you wish to be displayed

for eg. if I want to change the text from story text to You see a fork in the road in the label as shown in screenshot 1

In this case, our WHO is the label (element in the storyboard), WHAT is the text (property of element) and VALUE will be You see a fork in the road

so our final code will be as follows: Final code

screenshot 1 changes to screenshot 2 once the above code is executed.

I hope this solution helps you solve your issue. Thank you!

how to reference a YAML "setting" from elsewhere in the same YAML file?

In some languages, you can use an alternative library, For example, tampax is an implementation of YAML handling variables:

const tampax = require('tampax');

const yamlString = `
  name: Arthur
  favorite: Excalibur
  useless: knife
sentence: "{{}} use {{weapon.favorite}}. The goal is {{goal}}."`;

const r = tampax.yamlParseString(yamlString, { goal: 'to kill Mordred' });

// output : "Arthur use Excalibur. The goal is to kill Mordred."

Editor's Note: poster is also the author of this package.

How to determine the IP address of a Solaris system

/usr/sbin/ifconfig -a | awk 'BEGIN { count=0; } { if ( $1 ~ /inet/ ) { count++; if( count==2 ) { print $2; } } }'

This will list down the exact ip address for the machine

Read Session Id using Javascript

The following can be used to retrieve JSESSIONID:

function getJSessionId(){
    var jsId = document.cookie.match(/JSESSIONID=[^;]+/);
    if(jsId != null) {
        if (jsId instanceof Array)
            jsId = jsId[0].substring(11);
            jsId = jsId.substring(11);
    return jsId;

What is the best way to conditionally apply attributes in AngularJS?

To get an attribute to show a specific value based on a boolean check, or be omitted entirely if the boolean check failed, I used the following:

ng-attr-example="{{params.type == 'test' ? 'itWasTest' : undefined }}"

Example usage:

<div ng-attr-class="{{params.type == 'test' ? 'itWasTest' : undefined }}">

Would output <div class="itWasTest"> or <div> based on the value of params.type

Using SimpleXML to create an XML object from scratch

Sure you can. Eg.

$newsXML = new SimpleXMLElement("<news></news>");
$newsXML->addAttribute('newsPagePrefix', 'value goes here');
$newsIntro = $newsXML->addChild('content');
$newsIntro->addAttribute('type', 'latest');
Header('Content-type: text/xml');
echo $newsXML->asXML();


<?xml version="1.0"?>
<news newsPagePrefix="value goes here">
    <content type="latest"/>

Have fun.

Execute JavaScript using Selenium WebDriver in C#

the nuget package Selenium.Support already contains an extension method to help with this. Once it is included, one liner to executer script



  string result = Driver.ExecuteJavaScript<string>("console.clear()");

Checking for empty result (php, pdo, mysql)

what I'm doing wrong here?

Almost everything.

$today = date('Y-m-d'); // no need for strtotime

$sth = $db->prepare("SELECT id_email FROM db WHERE hardcopy = '1' AND hardcopy_date <= :today AND hardcopy_sent = '0' ORDER BY id_email ASC");

$sth->bindParam(':today',$today); // no need for PDO::PARAM_STR

$sth->execute(); // no need for if
$this->id_email = $sth->fetchAll(PDO::FETCH_COLUMN); // no need for while

return count($this->id_email); // no need for the everything else

effectively, you always have your fetched data (in this case in $this->id_email variable) to tell whether your query returned anything or not. Read more in my article on PDO.

Javascript array value is undefined ... how do I test for that

Check for

if (predQuery[preId] === undefined)

Use the strict equal to operator. See comparison operators

Calculate RSA key fingerprint

Run the following command to retrieve the SHA256 fingerprint of your SSH key (-l means "list" instead of create a new key, -f means "filename"):

$ ssh-keygen -lf /path/to/ssh/key

So for example, on my machine the command I ran was (using RSA public key):

$ ssh-keygen -lf ~/.ssh/
2048 00:11:22:33:44:55:66:77:88:99:aa:bb:cc:dd:ee:ff /Users/username/.ssh/ (RSA)

To get the GitHub (MD5) fingerprint format with newer versions of ssh-keygen, run:

$ ssh-keygen -E md5 -lf <fileName>

Bonus information:

ssh-keygen -lf also works on known_hosts and authorized_keys files.

To find most public keys on Linux/Unix/OS X systems, run

$ find /etc/ssh /home/*/.ssh /Users/*/.ssh -name '*.pub' -o -name 'authorized_keys' -o -name 'known_hosts'

(If you want to see inside other users' homedirs, you'll have to be root or sudo.)

The ssh-add -l is very similar, but lists the fingerprints of keys added to your agent. (OS X users take note that magic passwordless SSH via Keychain is not the same as using ssh-agent.)

Detecting negative numbers

Just multiply the number by -1 and check if the result is positive. Software caused connection abort: recv failed

The only time I've seen something like this happen is when I have a bad connection, or when somebody is closing the socket that I am using from a different thread context.

use current date as default value for a column

Select Table Column Name where you want to get default value of Current date

 ADD  CONSTRAINT [Constraint_Name] 
 DEFAULT (getdate()) FOR [Column_Name]

Alter Table Query

Alter TABLE [dbo].[Table_Name](
    [PDate] [datetime] Default GetDate())

Curly braces in string in PHP


$number = 4;
print "You have the {$number}th edition book";
//output: "You have the 4th edition book";

Without curly braces PHP would try to find a variable named $numberth, that doesn't exist!

Java 8: Lambda-Streams, Filter by Method with Exception

Use #propagate() method. Sample non-Guava implementation from Java 8 Blog by Sam Beran:

public class Throwables {
    public interface ExceptionWrapper<E> {
        E wrap(Exception e);

    public static <T> T propagate(Callable<T> callable) throws RuntimeException {
        return propagate(callable, RuntimeException::new);

    public static <T, E extends Throwable> T propagate(Callable<T> callable, ExceptionWrapper<E> wrapper) throws E {
        try {
        } catch (RuntimeException e) {
            throw e;
        } catch (Exception e) {
            throw wrapper.wrap(e);

iPad browser WIDTH & HEIGHT standard

There's no simple answer to this question. Apple's mobile version of WebKit, used in iPhones, iPod Touches, and iPads, will scale the page to fit the screen, at which point the user can zoom in and out freely.

That said, you can design your page to minimize the amount of zooming necessary. Your best bet is to make the width and height the same as the lower resolution of the iPad, since you don't know which way it's oriented; in other words, you would make your page 768x768, so that it will fit well on the iPad's screen whether it's oriented to be 1024x768 or 768x1024.

More importantly, you'd want to design your page with big controls with lots of space that are easy to hit with your thumbs - you could easily design a 768x768 page that was very cluttered and therefore required lots of zooming. To accomplish this, you'll likely want to divide your controls among a number of web pages.

On the other hand, it's not the most worthwhile pursuit. If while designing you find opportunities to make your page more "finger-friendly", then go for it...but the reality is that iPad users are very comfortable with moving around and zooming in and out of the page to get to things because it's necessary on most web sites. If anything, you probably want to design it so that it's conducive to this type of navigation.

Make boxes with relevant grouped data that can be easily double-tapped to focus on, and keep related controls close to each other. iPad users will most likely appreciate a page that facilitates the familiar zoom-and-pan navigation they're accustomed to more than they will a page that has fewer controls so that they don't have to.

How do I assign a null value to a variable in PowerShell?

These are automatic variables, like $null, $true, $false etc.

about_Automatic_Variables, see

$null is an automatic variable that contains a NULL or empty value. You can use this variable to represent an absent or undefined value in commands and scripts.

Windows PowerShell treats $null as an object with a value, that is, as an explicit placeholder, so you can use $null to represent an empty value in a series of values.

For example, when $null is included in a collection, it is counted as one of the objects.

C:\PS> $a = ".dir", $null, ".pdf"
C:\PS> $a.count

If you pipe the $null variable to the ForEach-Object cmdlet, it generates a value for $null, just as it does for the other objects.

PS C:\ps-test> ".dir", $null, ".pdf" | Foreach {"Hello"}

As a result, you cannot use $null to mean "no parameter value." A parameter value of $null overrides the default parameter value.

However, because Windows PowerShell treats the $null variable as a placeholder, you can use it scripts like the following one, which would not work if $null were ignored.

$calendar = @($null, $null, “Meeting”, $null, $null, “Team Lunch”, $null)
$days = Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"
$currentDay = 0

foreach($day in $calendar)
    if($day –ne $null)
        "Appointment on $($days[$currentDay]): $day"



Appointment on Tuesday: Meeting
Appointment on Friday: Team lunch

Task.Run with Parameter(s)?

Just use Task.Run

var task = Task.Run(() =>
    //this will already share scope with rawData, no need to use a placeholder

Or, if you would like to use it in a method and await the task later

public Task<T> SomethingAsync<T>()
    var task = Task.Run(() =>
        //presumably do something which takes a few ms here
        //this will share scope with any passed parameters in the method
        return default(T);

    return task;

JPA & Criteria API - Select only specific columns

You can do something like this

Session session = app.factory.openSession();
CriteriaBuilder builder = session.getCriteriaBuilder();
CriteriaQuery query = builder.createQuery();
Root<Users> root = query.from(Users.class);"firstname"));
String name = session.createQuery(query).getSingleResult();

where you can change "firstname" with the name of the column you want.

syntax for creating a dictionary into another dictionary in python

You can declare a dictionary inside a dictionary by nesting the {} containers:

d = {'dict1': {'foo': 1, 'bar': 2}, 'dict2': {'baz': 3, 'quux': 4}}

And then you can access the elements using the [] syntax:

print d['dict1']           # {'foo': 1, 'bar': 2}
print d['dict1']['foo']    # 1
print d['dict2']['quux']   # 4

Given the above, if you want to add another dictionary to the dictionary, it can be done like so:

d['dict3'] = {'spam': 5, 'ham': 6}

or if you prefer to add items to the internal dictionary one by one:

d['dict4'] = {}
d['dict4']['king'] = 7
d['dict4']['queen'] = 8

map function for objects (instead of arrays)

Based on @Amberlamps answer, here's a utility function (as a comment it looked ugly)

function mapObject(obj, mapFunc){
    return Object.keys(obj).reduce(function(newObj, value) {
        newObj[value] = mapFunc(obj[value]);
        return newObj;
    }, {});

and the use is:

var obj = {a:1, b:3, c:5}
function double(x){return x * 2}

var newObj = mapObject(obj, double);
//=>  {a: 2, b: 6, c: 10}

Append data frames together in a for loop

Try to use rbindlist approach over rbind as it's very, very fast.



##### example 1: slow processing ######

table.1 <- data.frame(x = NA, y = NA)
time.taken <- 0
for( i in 1:100) {
  start.time = Sys.time()
  x <- rnorm(100)
  y <- x/2 +x/3
  z <- = x, y = y)

  table.1 <- rbind(table.1, z)
  end.time <- Sys.time()
  time.taken  <- (end.time - start.time) + time.taken

> Time difference of 0.1637917 secs

####example 2: faster processing #####

table.2 <- list()
t0 <- 0
for( i in 1:100) {
  s0 = Sys.time()
  x <- rnorm(100)
  y <- x/2 + x/3

  z <- = x, y = y)

  table.2[[i]] <- z

  e0 <- Sys.time()
  t0  <- (e0 - s0) + t0

s1 = Sys.time()
table.3 <- rbindlist(table.2)
e1 = Sys.time()

t1  <- (e1-s1) + t0
> Time difference of 0.03064394 secs

How do you modify the web.config appSettings at runtime?

Try This:

using System;
using System.Configuration;
using System.Web.Configuration;

namespace SampleApplication.WebConfig
    public partial class webConfigFile : System.Web.UI.Page
        protected void Page_Load(object sender, EventArgs e)
            //Helps to open the Root level web.config file.
            Configuration webConfigApp = WebConfigurationManager.OpenWebConfiguration("~");
            //Modifying the AppKey from AppValue to AppValue1
            webConfigApp.AppSettings.Settings["ConnectionString"].Value = "ConnectionString";
            //Save the Modified settings of AppSettings.

how to include glyphicons in bootstrap 3

I think your particular problem isn't how to use Glyphicons but understanding how Bootstrap files work together.

Bootstrap requires a specific file structure to work. I see from your code you have this:

<link href="bootstrap.css" rel="stylesheet" media="screen">

Your Bootstrap.css is being loaded from the same location as your page, this would create a problem if you didn't adjust your file structure.

But first, let me recommend you setup your folder structure like so:

/css      <-- Bootstrap.css here
/fonts    <-- Bootstrap fonts here
/js       <-- Bootstrap JavaScript here

If you notice, this is also how Bootstrap structures its files in its download ZIP.

You then include your Bootstrap file like so:

<link href="css/bootstrap.css" rel="stylesheet" media="screen">
<link href="./css/bootstrap.css" rel="stylesheet" media="screen">
<link href="/css/bootstrap.css" rel="stylesheet" media="screen">

Depending on your server structure or what you're going for.

The first and second are relative to your file's current directory. The second one is just more explicit by saying "here" (./) first then css folder (/css).

The third is good if you're running a web server, and you can just use relative to root notation as the leading "/" will be always start at the root folder.

So, why do this?

Bootstrap.css has this specific line for Glyphfonts:

@font-face {
    font-family: 'Glyphicons Halflings';
    src: url('../fonts/glyphicons-halflings-regular.eot');
    src: url('../fonts/glyphicons-halflings-regular.eot?#iefix') format('embedded-opentype'), url('../fonts/glyphicons-halflings-regular.woff') format('woff'), url('../fonts/glyphicons-halflings-regular.ttf') format('truetype'), url('../fonts/glyphicons-halflings-regular.svg#glyphicons-halflingsregular') format('svg');

What you can see is that that Glyphfonts are loaded by going up one directory ../ and then looking for a folder called /fonts and THEN loading the font file.

The URL address is relative to the location of the CSS file. So, if your CSS file is at the same location like this:


The CSS file is going one level deeper than looking for a /fonts folder.

So, let's say the actual location of these files are:


The CSS file would technically be looking for a folder at:


but your folder is actually in:


So see if that helps. You don't have to do anything 'special' to load Bootstrap Glyphicons, except make sure your folder structure is set up appropriately.

When you get that fixed, your HTML should simply be:

<span class="glyphicon glyphicon-comment"></span>

Note, you need both classes. The first class glyphicon sets up the basic styles while glyphicon-comment sets the specific image.

How to select records without duplicate on just one field in SQL?

select Country_id,country_title from(
   select Country_id,country_title,row_number() over (partition by country_title 
   order by Country_id  ) rn from country)a
   where rn=1;

Passing variable from Form to Module in VBA

Siddharth's answer is nice, but relies on globally-scoped variables. There's a better, more OOP-friendly way.

A UserForm is a class module like any other - the only difference is that it has a hidden VB_PredeclaredId attribute set to True, which makes VB create a global-scope object variable named after the class - that's how you can write UserForm1.Show without creating a new instance of the class.

Step away from this, and treat your form as an object instead - expose Property Get members and abstract away the form's controls - the calling code doesn't care about controls anyway:

Option Explicit
Private cancelling As Boolean

Public Property Get UserId() As String
    UserId = txtUserId.Text
End Property

Public Property Get Password() As String
    Password = txtPassword.Text
End Property

Public Property Get IsCancelled() As Boolean
    IsCancelled = cancelling
End Property

Private Sub OkButton_Click()
End Sub

Private Sub CancelButton_Click()
    cancelling = True
End Sub

Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer)
    If CloseMode = VbQueryClose.vbFormControlMenu Then
        cancelling = True
        Cancel = True
    End If
End Sub

Now the calling code can do this (assuming the UserForm was named LoginPrompt):

With New LoginPrompt
    .Show vbModal
    If .IsCancelled Then Exit Sub
    DoSomething .UserId, .Password
End With

Where DoSomething would be some procedure that requires the two string parameters:

Private Sub DoSomething(ByVal uid As String, ByVal pwd As String)
    'work with the parameter values, regardless of where they came from
End Sub

https with WCF error: "Could not find base address that matches scheme https"

It turned out that my problem was that I was using a load balancer to handle the SSL, which then sent it over http to the actual server, which then complained.

Description of a fix is here:

Edit: I fixed my problem, which was slightly different, after talking to microsoft support.

My silverlight app had its endpoint address in code going over https to the load balancer. The load balancer then changed the endpoint address to http and to point to the actual server that it was going to. So on each server's web config I added a listenUri for the endpoint that was http instead of https

<endpoint address="" listenUri="http://[LOAD_BALANCER_ADDRESS]" ... />

Properties file in python (similar to Java Properties)

You can use a file-like object in ConfigParser.RawConfigParser.readfp defined here ->

Define a class that overrides readline that adds a section name before the actual contents of your properties file.

I've packaged it into the class that returns a dict of all the properties defined.

import ConfigParser

class PropertiesReader(object):

    def __init__(self, properties_file_name): = properties_file_name
        self.main_section = 'main'

        # Add dummy section on top
        self.lines = [ '[%s]\n' % self.main_section ]

        with open(properties_file_name) as f:

        # This makes sure that iterator in readfp stops

    def readline(self):
        return self.lines.pop(0)

    def read_properties(self):
        config = ConfigParser.RawConfigParser()

        # Without next line the property names will be lowercased
        config.optionxform = str

        return dict(config.items(self.main_section))

if __name__ == '__main__':
    print PropertiesReader('/path/to/').read_properties()

Error reading JObject from JsonReader. Current JsonReader item is not an object: StartArray. Path

I ran into a very similar problem with my Xamarin Windows Phone 8.1 app. The reason JObject.Parse(json) would not work for me was because my Json had a beginning "[" and an ending "]". In order to make it work, I had to remove those two characters. From your example, it looks like you might have the same issue.

jsonResult = jsonResult.TrimStart(new char[] { '[' }).TrimEnd(new char[] { ']' });

I was then able to use the JObject.Parse(jsonResult) and everything worked.

How do I convert an ANSI encoded file to UTF-8 with Notepad++?

Maybe this is not the answer you needed, but I encountered similar problem, so I decided to put it here.

I needed to convert 500 xml files to UTF8 via Notepad++. Why Notepad++? When I used the option "Encode in UTF8" (many other converters use the same logic) it messed up all special characters, so I had to use "Convert to UTF8" explicitly.

Here some simple steps to convert multiple files via Notepad++ without messing up with special characters (for ex. diacritical marks).

  1. Run Notepad++ and then open menu Plugins->Plugin Manager->Show Plugin Manager
  2. Install Python Script. When plugin is installed, restart the application.
  3. Choose menu Plugins->Python Script->New script.
  4. Choose its name, and then past the following code:

import os
import sys
from Npp import notepad # import it first!

filePathSrc="C:\\Users\\" # Path to the folder with files to convert
for root, dirs, files in os.walk(filePathSrc):
    for fn in files: 
        if fn[-4:] == '.xml': # Specify type of the files
   + "\\" + fn)      
            notepad.runMenuCommand("Encoding", "Convert to UTF-8")
            # if you try to save/replace the file, an annoying confirmation window would popup.
            notepad.saveAs("{}{}".format(fn[:-4], '_utf8.xml')) 

After all, run the script

Transfer data from one database to another database

Example for insert into values in One database table into another database table

insert into dbo.onedatabase.FolderStatus

select [FolderStatusId], [code], [title], [last_modified]
from dbo.Twodatabase.f_file_stat

Best TCP port number range for internal applications

I can't see why you would care. Other than the "don't use ports below 1024" privilege rule, you should be able to use any port because your clients should be configurable to talk to any IP address and port!

If they're not, then they haven't been done very well. Go back and do them properly :-)

In other words, run the server at IP address X and port Y then configure clients with that information. Then, if you find you must run a different server on X that conflicts with your Y, just re-configure your server and clients to use a new port. This is true whether your clients are code, or people typing URLs into a browser.

I, like you, wouldn't try to get numbers assigned by IANA since that's supposed to be for services so common that many, many environments will use them (think SSH or FTP or TELNET).

Your network is your network and, if you want your servers on port 1234 (or even the TELNET or FTP ports for that matter), that's your business. Case in point, in our mainframe development area, port 23 is used for the 3270 terminal server which is a vastly different beast to telnet. If you want to telnet to the UNIX side of the mainframe, you use port 1023. That's sometimes annoying if you use telnet clients without specifying port 1023 since it hooks you up to a server that knows nothing of the telnet protocol - we have to break out of the telnet client and do it properly:

telnet 1023

If you really can't make the client side configurable, pick one in the second range, like 48042, and just use it, declaring that any other software on those boxes (including any added in the future) has to keep out of your way.

Creating a daemon in Linux

If your app is one of:

  ".sh": "bash",
  ".py": "python",
  ".rb": "ruby",
  ".coffee" : "coffee",
  ".php": "php",
  ".pl" : "perl",
  ".js" : "node"

and you don't mind a NodeJS dependency then install NodeJS and then:

npm install -g pm2

pm2 start yourapp.yourext --name "fred" # where .yourext is one of the above

pm2 start yourapp.yourext -i 0 --name "fred" # run your app on all cores

pm2 list

To keep all apps running on reboot (and daemonise pm2):

pm2 startup

pm2 save

Now you can:

service pm2 stop|restart|start|status

(also easily allows you to watch for code changes in your app directory and auto restart the app process when a code change happens)

Fastest way to get the first object from a queryset in django?

You can use array slicing:


Which can be used with .filter():


You wouldn't want to first turn it into a list because that would force a full database call of all the records. Just do the above and it will only pull the first. You could even use .order_by() to ensure you get the first you want.

Be sure to add the .get() or else you will get a QuerySet back and not an object.

How do I get the current date in JavaScript?

To get just the date then it is built in to javascript:

new Date();

If you are looking for date formatting and you are anyways using the Kendo JQuery UI library for your site then I suggest using the built in kendo function:

kendo.toString(new Date(), "yyMMdd"); //or any other typical date format

For a full list of supported formats see here

Arithmetic operation resulted in an overflow. (Adding integers)

The maximum value of an integer (which is signed) is 2147483647. If that value overflows, an exception is thrown to prevent unexpected behavior of your program.

If that exception wouldn't be thrown, you'd have a value of -2145629296 for your Volume, which is most probably not wanted.

Solution: Use an Int64 for your volume. With a max value of 9223372036854775807, you're probably more on the safe side.

Guzzle 6: no more json() method for responses

Adding ->getContents() doesn't return jSON response, instead it returns as text.

You can simply use json_decode

How to find if a file contains a given string using Windows command line

I've used a DOS command line to do this. Two lines, actually. The first one to make the "current directory" the folder where the file is - or the root folder of a group of folders where the file can be. The second line does the search.

CD C:\TheFolder
C:\TheFolder>FINDSTR /L /S /I /N /C:"TheString" *.PRG

You can find details about the parameters at this link.

Hope it helps!

mysqli::mysqli(): (HY000/2002): Can't connect to local MySQL server through socket 'MySQL' (2)

When you use just "localhost" the MySQL client library tries to use a Unix domain socket for the connection instead of a TCP/IP connection. The error is telling you that the socket, called MySQL, cannot be used to make the connection, probably because it does not exist (error number 2).

From the MySQL Documentation:

On Unix, MySQL programs treat the host name localhost specially, in a way that is likely different from what you expect compared to other network-based programs. For connections to localhost, MySQL programs attempt to connect to the local server by using a Unix socket file. This occurs even if a --port or -P option is given to specify a port number. To ensure that the client makes a TCP/IP connection to the local server, use --host or -h to specify a host name value of, or the IP address or name of the local server. You can also specify the connection protocol explicitly, even for localhost, by using the --protocol=TCP option.

There are a few ways to solve this problem.

  1. You can just use TCP/IP instead of the Unix socket. You would do this by using instead of localhost when you connect. The Unix socket might by faster and safer to use, though.
  2. You can change the socket in php.ini: open the MySQL configuration file my.cnf to find where MySQL creates the socket, and set PHP's mysqli.default_socket to that path. On my system it's /var/run/mysqld/mysqld.sock.
  3. Configure the socket directly in the PHP script when opening the connection. For example:

    $db = new MySQLi('localhost', 'kamil', '***', '', 0, 

Difference between SET autocommit=1 and START TRANSACTION in mysql (Have I missed something?)

If you want to use rollback, then use start transaction and otherwise forget all those things,

By default, MySQL automatically commits the changes to the database.

To force MySQL not to commit these changes automatically, execute following:

SET autocommit = 0;
SET autocommit = OFF

To enable the autocommit mode explicitly:

SET autocommit = 1;
SET autocommit = ON;

How to list physical disks?

Thic WMIC command combination works fine:

wmic volume list brief

Openssl is not recognized as an internal or external command

go to bin folder path in cmd and then run following command

keytool -exportcert -alias androiddebugkey -keystore %HOMEPATH%\.android\debug.keystore | openssl sha1 -binary | openssl base64

you will get your key hash

Operand type clash: int is incompatible with date + The INSERT statement conflicted with the FOREIGN KEY constraint

Try wrapping your dates in single quotes, like this:


It should be able to parse the date this way.

Invalid CSRF Token 'null' was found on the request parameter '_csrf' or header 'X-CSRF-TOKEN'

I used to have the same problem.

Your config use security="none" so cannot generate _csrf:

<http pattern="/login.jsp" security="none"/>

you can set access="IS_AUTHENTICATED_ANONYMOUSLY" for page /login.jsp replace above config:

    <intercept-url pattern="/login.jsp*" access="IS_AUTHENTICATED_ANONYMOUSLY"/>
    <intercept-url pattern="/**" access="ROLE_USER"/>
    <form-login login-page="/login.jsp"
    <csrf />

How to Generate unique file names in C#

I've written a simple recursive function that generates file names like Windows does, by appending a sequence number prior to the file extension.

Given a desired file path of C:\MyDir\MyFile.txt, and the file already exists, it returns a final file path of C:\MyDir\MyFile_1.txt.

It is called like this:

var desiredPath = @"C:\MyDir\MyFile.txt";
var finalPath = UniqueFileName(desiredPath);

private static string UniqueFileName(string path, int count = 0)
    if (count == 0)
        if (!File.Exists(path))
            return path;
        var candidatePath = string.Format(

        if (!File.Exists(candidatePath))
            return candidatePath;

    return UniqueFileName(path, count);

Delete duplicate records from a SQL table without a primary key

Having a database table without Primary Key is really and will say extremely BAD after you add one (ALTER TABLE)

Run this until you don't see any more duplicated records (that is the purpose of HAVING COUNT)

    SELECT MAX([Id])
    HAVING COUNT(*) > 1


MAX([Id]) will cause to delete latest records (ones added after first created) in case you want the opposite meaning that in case of requiring deleting first records and leave the last record inserted please use MIN([Id])

Append value to empty vector in R?

> vec <- c(letters[1:3]) # vec <- c("a","b","c") ; or just empty vector: vec <- c()

> values<- c(1,2,3)

> for (i in 1:length(values)){
      print(paste("length of vec", length(vec))); 
      vec[length(vec)+1] <- values[i]  #Appends value at the end of vector

[1] "length of vec 3"
[1] "length of vec 4"
[1] "length of vec 5"

> vec
[1] "a" "b" "c" "1" "2" "3"

IntelliJ IDEA "The selected directory is not a valid home for JDK"

For Windows, apparently the JDK has to be under C:\Program Files.

This does not work:


This works:

C:\Program Files\Java\jdk1.8.0_191     

(I'm using IntelliJ IDEA Ultimate 2018.2.4.)

How to check for file lock?

When I faced with a similar problem, I finished with the following code:

public bool IsFileLocked(string filePath)
        using (File.Open(filePath, FileMode.Open)){}
    catch (IOException e)
        var errorCode = Marshal.GetHRForException(e) & ((1 << 16) - 1);

        return errorCode == 32 || errorCode == 33;

    return false;

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '...' is therefore not allowed access

Why the error is raised:

JavaScript code is limited by the same-origin policy, meaning, from a page at, you can only make (AJAX) requests to services located at exactly the same domain, in that case, exactly (not - without the www - or

In your case, your Ajax code is trying to reach a service in from a page located at

Although very similar, they are not the same domain. And when they are not on the same domain, the request will only be successful if the target's respose contains a Access-Control-Allow-Origin header in it.

As your page/service at was never configured to present such header, that error message is shown.


As said, the origin (where the page with JavaScript is at) and the target (where the JavaScript is trying to reach) domains must be the exact same.

Your case seems like a typo. Looks like and are actually the same server/domain. So to fix, type the target and the origin equally: make you Ajax code request pages/services to not (Maybe place the target URL relatively, like '/login.php', without the domain).

On a more general note:

If the problem is not a typo like the one of this question seems to be, the solution would be to add the Access-Control-Allow-Origin to the target domain. To add it, depends, of course, of the server/language behind that address. Sometimes a configuration variable in the tool will do the trick. Other times you'll have to add the headers through code yourself.

Bash conditionals: how to "and" expressions? (if [ ! -z $VAR && -e $VAR ])

Simply quote your variable:

[ -e "$VAR" ]

This evaluates to [ -e "" ] if $VAR is empty.

Your version does not work because it evaluates to [ -e ]. Now in this case, bash simply checks if the single argument (-e) is a non-empty string.

From the manpage:

test and [ evaluate conditional expressions using a set of rules based on the number of arguments. ...

1 argument

The expression is true if and only if the argument is not null.

(Also, this solution has the additional benefit of working with filenames containing spaces)

How to do a JUnit assert on a message in a logger

Here is what i did for logback.

I created a TestAppender class:

public class TestAppender extends AppenderBase<ILoggingEvent> {

    private Stack<ILoggingEvent> events = new Stack<ILoggingEvent>();

    protected void append(ILoggingEvent event) {

    public void clear() {

    public ILoggingEvent getLastEvent() {
        return events.pop();

Then in the parent of my testng unit test class I created a method:

protected TestAppender testAppender;

public void setupLogsForTesting() {
    Logger root = (Logger)LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
    testAppender = (TestAppender)root.getAppender("TEST");
    if (testAppender != null) {

I have a logback-test.xml file defined in src/test/resources and I added a test appender:

<appender name="TEST" class="">

and added this appender to the root appender:

    <level value="error" />
    <appender-ref ref="STDOUT" />
    <appender-ref ref="TEST" />

Now in my test classes that extend from my parent test class I can get the appender and get the last message logged and verify the message, the level, the throwable.

ILoggingEvent lastEvent = testAppender.getLastEvent();
assertEquals(lastEvent.getMessage(), "...");
assertEquals(lastEvent.getLevel(), Level.WARN);
assertEquals(lastEvent.getThrowableProxy().getMessage(), "...");

What are best practices that you use when writing Objective-C and Cocoa?

Some of these have already been mentioned, but here's what I can think of off the top of my head:

  • Follow KVO naming rules. Even if you don't use KVO now, in my experience often times it's still beneficial in the future. And if you are using KVO or bindings, you need to know things are going work the way they are supposed to. This covers not just accessor methods and instance variables, but to-many relationships, validation, auto-notifying dependent keys, and so on.
  • Put private methods in a category. Not just the interface, but the implementation as well. It's good to have some distance conceptually between private and non-private methods. I include everything in my .m file.
  • Put background thread methods in a category. Same as above. I've found it's good to keep a clear conceptual barrier when you're thinking about what's on the main thread and what's not.
  • Use #pragma mark [section]. Usually I group by my own methods, each subclass's overrides, and any information or formal protocols. This makes it a lot easier to jump to exactly what I'm looking for. On the same topic, group similar methods (like a table view's delegate methods) together, don't just stick them anywhere.
  • Prefix private methods & ivars with _. I like the way it looks, and I'm less likely to use an ivar when I mean a property by accident.
  • Don't use mutator methods / properties in init & dealloc. I've never had anything bad happen because of it, but I can see the logic if you change the method to do something that depends on the state of your object.
  • Put IBOutlets in properties. I actually just read this one here, but I'm going to start doing it. Regardless of any memory benefits, it seems better stylistically (at least to me).
  • Avoid writing code you don't absolutely need. This really covers a lot of things, like making ivars when a #define will do, or caching an array instead of sorting it each time the data is needed. There's a lot I could say about this, but the bottom line is don't write code until you need it, or the profiler tells you to. It makes things a lot easier to maintain in the long run.
  • Finish what you start. Having a lot of half-finished, buggy code is the fastest way to kill a project dead. If you need a stub method that's fine, just indicate it by putting NSLog( @"stub" ) inside, or however you want to keep track of things.

Writing your own square root function

Depending on your needs, a simple divide-and-conquer strategy can be used. It won't converge as fast as some other methods but it may be a lot easier for a novice to understand. In addition, since it's an O(log n) algorithm (halving the search space each iteration), the worst case for a 32-bit float will be 32 iterations.

Let's say you want the square root of 62.104. You pick a value halfway between 0 and that, and square it. If the square is higher than your number, you need to concentrate on numbers less than the midpoint. If it's too low, concentrate on those higher.

With real math, you could keep dividing the search space in two forever (if it doesn't have a rational square root). In reality, computers will eventually run out of precision and you'll have your approximation. The following C program illustrates the point:

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

int main (int argc, char *argv[]) {
    float val, low, high, mid, oldmid, midsqr;
    int step = 0;

    // Get argument, force to non-negative.

    if (argc < 2) {
        printf ("Usage: sqrt <number>\n");
        return 1;
    val = fabs (atof (argv[1]));

    // Set initial bounds and print heading.

    low = 0;
    high = mid = val;
    oldmid = -1;

    printf ("%4s  %10s  %10s  %10s  %10s  %10s    %s\n",
        "Step", "Number", "Low", "High", "Mid", "Square", "Result");

    // Keep going until accurate enough.

    while (fabs(oldmid - mid) >= 0.00001) {
        oldmid = mid;

        // Get midpoint and see if we need lower or higher.

        mid = (high + low) / 2;
        midsqr = mid * mid;
        printf ("%4d  %10.4f  %10.4f  %10.4f  %10.4f  %10.4f  ",
            ++step, val, low, high, mid, midsqr);
        if (mid * mid > val) {
            high = mid;
            printf ("- too high\n");
        } else {
            low = mid;
            printf ("- too low\n");

    // Desired accuracy reached, print it.

    printf ("sqrt(%.4f) = %.4f\n", val, mid);
    return 0;

Here's a couple of runs so you hopefully get an idea how it works. For 77:

pax> sqrt 77
Step      Number         Low        High         Mid      Square    Result
   1     77.0000      0.0000     77.0000     38.5000   1482.2500  - too high
   2     77.0000      0.0000     38.5000     19.2500    370.5625  - too high
   3     77.0000      0.0000     19.2500      9.6250     92.6406  - too high
   4     77.0000      0.0000      9.6250      4.8125     23.1602  - too low
   5     77.0000      4.8125      9.6250      7.2188     52.1104  - too low
   6     77.0000      7.2188      9.6250      8.4219     70.9280  - too low
   7     77.0000      8.4219      9.6250      9.0234     81.4224  - too high
   8     77.0000      8.4219      9.0234      8.7227     76.0847  - too low
   9     77.0000      8.7227      9.0234      8.8730     78.7310  - too high
  10     77.0000      8.7227      8.8730      8.7979     77.4022  - too high
  11     77.0000      8.7227      8.7979      8.7603     76.7421  - too low
  12     77.0000      8.7603      8.7979      8.7791     77.0718  - too high
  13     77.0000      8.7603      8.7791      8.7697     76.9068  - too low
  14     77.0000      8.7697      8.7791      8.7744     76.9893  - too low
  15     77.0000      8.7744      8.7791      8.7767     77.0305  - too high
  16     77.0000      8.7744      8.7767      8.7755     77.0099  - too high
  17     77.0000      8.7744      8.7755      8.7749     76.9996  - too low
  18     77.0000      8.7749      8.7755      8.7752     77.0047  - too high
  19     77.0000      8.7749      8.7752      8.7751     77.0022  - too high
  20     77.0000      8.7749      8.7751      8.7750     77.0009  - too high
  21     77.0000      8.7749      8.7750      8.7750     77.0002  - too high
  22     77.0000      8.7749      8.7750      8.7750     76.9999  - too low
  23     77.0000      8.7750      8.7750      8.7750     77.0000  - too low
sqrt(77.0000) = 8.7750

For 62.104:

pax> sqrt 62.104
Step      Number         Low        High         Mid      Square    Result
   1     62.1040      0.0000     62.1040     31.0520    964.2267  - too high
   2     62.1040      0.0000     31.0520     15.5260    241.0567  - too high
   3     62.1040      0.0000     15.5260      7.7630     60.2642  - too low
   4     62.1040      7.7630     15.5260     11.6445    135.5944  - too high
   5     62.1040      7.7630     11.6445      9.7037     94.1628  - too high
   6     62.1040      7.7630      9.7037      8.7334     76.2718  - too high
   7     62.1040      7.7630      8.7334      8.2482     68.0326  - too high
   8     62.1040      7.7630      8.2482      8.0056     64.0895  - too high
   9     62.1040      7.7630      8.0056      7.8843     62.1621  - too high
  10     62.1040      7.7630      7.8843      7.8236     61.2095  - too low
  11     62.1040      7.8236      7.8843      7.8540     61.6849  - too low
  12     62.1040      7.8540      7.8843      7.8691     61.9233  - too low
  13     62.1040      7.8691      7.8843      7.8767     62.0426  - too low
  14     62.1040      7.8767      7.8843      7.8805     62.1024  - too low
  15     62.1040      7.8805      7.8843      7.8824     62.1323  - too high
  16     62.1040      7.8805      7.8824      7.8815     62.1173  - too high
  17     62.1040      7.8805      7.8815      7.8810     62.1098  - too high
  18     62.1040      7.8805      7.8810      7.8807     62.1061  - too high
  19     62.1040      7.8805      7.8807      7.8806     62.1042  - too high
  20     62.1040      7.8805      7.8806      7.8806     62.1033  - too low
  21     62.1040      7.8806      7.8806      7.8806     62.1038  - too low
  22     62.1040      7.8806      7.8806      7.8806     62.1040  - too high
  23     62.1040      7.8806      7.8806      7.8806     62.1039  - too high
sqrt(62.1040) = 7.8806

For 49:

pax> sqrt 49
Step      Number         Low        High         Mid      Square    Result
   1     49.0000      0.0000     49.0000     24.5000    600.2500  - too high
   2     49.0000      0.0000     24.5000     12.2500    150.0625  - too high
   3     49.0000      0.0000     12.2500      6.1250     37.5156  - too low
   4     49.0000      6.1250     12.2500      9.1875     84.4102  - too high
   5     49.0000      6.1250      9.1875      7.6562     58.6182  - too high
   6     49.0000      6.1250      7.6562      6.8906     47.4807  - too low
   7     49.0000      6.8906      7.6562      7.2734     52.9029  - too high
   8     49.0000      6.8906      7.2734      7.0820     50.1552  - too high
   9     49.0000      6.8906      7.0820      6.9863     48.8088  - too low
  10     49.0000      6.9863      7.0820      7.0342     49.4797  - too high
  11     49.0000      6.9863      7.0342      7.0103     49.1437  - too high
  12     49.0000      6.9863      7.0103      6.9983     48.9761  - too low
  13     49.0000      6.9983      7.0103      7.0043     49.0598  - too high
  14     49.0000      6.9983      7.0043      7.0013     49.0179  - too high
  15     49.0000      6.9983      7.0013      6.9998     48.9970  - too low
  16     49.0000      6.9998      7.0013      7.0005     49.0075  - too high
  17     49.0000      6.9998      7.0005      7.0002     49.0022  - too high
  18     49.0000      6.9998      7.0002      7.0000     48.9996  - too low
  19     49.0000      7.0000      7.0002      7.0001     49.0009  - too high
  20     49.0000      7.0000      7.0001      7.0000     49.0003  - too high
  21     49.0000      7.0000      7.0000      7.0000     49.0000  - too low
  22     49.0000      7.0000      7.0000      7.0000     49.0001  - too high
  23     49.0000      7.0000      7.0000      7.0000     49.0000  - too high
sqrt(49.0000) = 7.0000

Can't connect to localhost on SQL Server Express 2012 / 2016

Try changing the User that owns the service to Local System or use your admin account.

Under services, I changed the Service SQL Server (MSSQLSERVER) Log On from NT Service\Sql... To Local System. Right click the service and go to the Log On Tab and select the radio button Local System Account. You could also force another User to run it too if that fits better.

Using current time in UTC as default value in PostgreSQL

What about


If your other timestamp are without time zone then this cast will yield the matching type "timestamp without time zone" for the current time.

I would like to read what others think about that option, though. I still don't trust in my understanding of this "with/without" time zone stuff.

EDIT: Adding Michael Ekoka's comment here because it clarifies an important point:

Caveat. The question is about generating default timestamp in UTC for a timestamp column that happens to not store the time zone (perhaps because there's no need to store the time zone if you know that all your timestamps share the same). What your solution does is to generate a local timestamp (which for most people will not necessarily be set to UTC) and store it as a naive timestamp (one that does not specify its time zone).

Can't connect to MySQL server on '' (10061) (2003)

I was facing the same problem, but what I did not realise is that I did not have the MySQL Server installed. You must simply install the MySQL Server.

In order to install the MySQL server, you must run the "MySql Installer" and then press the "Add" button and then choose the "MySQL Server" in the tree.

After doing that, run you workbench again and you'll notice that there'll already be a connection configured. Hopefully, you'll be able to create a new connection or as many connections as you want.

Ignoring a class property in Entity Framework 4.1 Code First

As of EF 5.0, you need to include the System.ComponentModel.DataAnnotations.Schema namespace.

Is there an onSelect event or equivalent for HTML <select>?

The wonderful thing about the select tag (in this scenario) is that it will grab its value from the option tags.


<select onChange="javascript:doSomething(this.value);">
<option value="A">A</option>
<option value="B">B</option>
<option value="Foo">C</option>

Worked decent for me.

What are all possible pos tags of NLTK?

To save some folks some time, here is a list I extracted from a small corpus. I do not know if it is complete, but it should have most (if not all) of the help definitions from upenn_tagset...

CC: conjunction, coordinating

& 'n and both but either et for less minus neither nor or plus so
therefore times v. versus vs. whether yet

CD: numeral, cardinal

mid-1890 nine-thirty forty-two one-tenth ten million 0.5 one forty-
seven 1987 twenty '79 zero two 78-degrees eighty-four IX '60s .025
fifteen 271,124 dozen quintillion DM2,000 ...

DT: determiner

all an another any both del each either every half la many much nary
neither no some such that the them these this those

EX: existential there


IN: preposition or conjunction, subordinating

astride among uppon whether out inside pro despite on by throughout
below within for towards near behind atop around if like until below
next into if beside ...

JJ: adjective or numeral, ordinal

third ill-mannered pre-war regrettable oiled calamitous first separable
ectoplasmic battery-powered participatory fourth still-to-be-named
multilingual multi-disciplinary ...

JJR: adjective, comparative

bleaker braver breezier briefer brighter brisker broader bumper busier
calmer cheaper choosier cleaner clearer closer colder commoner costlier
cozier creamier crunchier cuter ...

JJS: adjective, superlative

calmest cheapest choicest classiest cleanest clearest closest commonest
corniest costliest crassest creepiest crudest cutest darkest deadliest
dearest deepest densest dinkiest ...

LS: list item marker

A A. B B. C C. D E F First G H I J K One SP-44001 SP-44002 SP-44005
SP-44007 Second Third Three Two * a b c d first five four one six three

MD: modal auxiliary

can cannot could couldn't dare may might must need ought shall should
shouldn't will would

NN: noun, common, singular or mass

common-carrier cabbage knuckle-duster Casino afghan shed thermostat
investment slide humour falloff slick wind hyena override subhumanity
machinist ...

NNP: noun, proper, singular

Motown Venneboerger Czestochwa Ranzer Conchita Trumplane Christos
Oceanside Escobar Kreisler Sawyer Cougar Yvette Ervin ODI Darryl CTCA
Shannon A.K.C. Meltex Liverpool ...

NNS: noun, common, plural

undergraduates scotches bric-a-brac products bodyguards facets coasts
divestitures storehouses designs clubs fragrances averages
subjectivists apprehensions muses factory-jobs ...

PDT: pre-determiner

all both half many quite such sure this

POS: genitive marker

' 's

PRP: pronoun, personal

hers herself him himself hisself it itself me myself one oneself ours
ourselves ownself self she thee theirs them themselves they thou thy us

PRP$: pronoun, possessive

her his mine my our ours their thy your

RB: adverb

occasionally unabatingly maddeningly adventurously professedly
stirringly prominently technologically magisterially predominately
swiftly fiscally pitilessly ...

RBR: adverb, comparative

further gloomier grander graver greater grimmer harder harsher
healthier heavier higher however larger later leaner lengthier less-
perfectly lesser lonelier longer louder lower more ...

RBS: adverb, superlative

best biggest bluntest earliest farthest first furthest hardest
heartiest highest largest least less most nearest second tightest worst

RP: particle

aboard about across along apart around aside at away back before behind
by crop down ever fast for forth from go high i.e. in into just later
low more off on open out over per pie raising start teeth that through
under unto up up-pp upon whole with you

TO: "to" as preposition or infinitive marker


UH: interjection

Goodbye Goody Gosh Wow Jeepers Jee-sus Hubba Hey Kee-reist Oops amen
huh howdy uh dammit whammo shucks heck anyways whodunnit honey golly
man baby diddle hush sonuvabitch ...

VB: verb, base form

ask assemble assess assign assume atone attention avoid bake balkanize
bank begin behold believe bend benefit bevel beware bless boil bomb
boost brace break bring broil brush build ...

VBD: verb, past tense

dipped pleaded swiped regummed soaked tidied convened halted registered
cushioned exacted snubbed strode aimed adopted belied figgered
speculated wore appreciated contemplated ...

VBG: verb, present participle or gerund

telegraphing stirring focusing angering judging stalling lactating
hankerin' alleging veering capping approaching traveling besieging
encrypting interrupting erasing wincing ...

VBN: verb, past participle

multihulled dilapidated aerosolized chaired languished panelized used
experimented flourished imitated reunifed factored condensed sheared
unsettled primed dubbed desired ...

VBP: verb, present tense, not 3rd person singular

predominate wrap resort sue twist spill cure lengthen brush terminate
appear tend stray glisten obtain comprise detest tease attract
emphasize mold postpone sever return wag ...

VBZ: verb, present tense, 3rd person singular

bases reconstructs marks mixes displeases seals carps weaves snatches
slumps stretches authorizes smolders pictures emerges stockpiles
seduces fizzes uses bolsters slaps speaks pleads ...

WDT: WH-determiner

that what whatever which whichever

WP: WH-pronoun

that what whatever whatsoever which who whom whosoever

WRB: Wh-adverb

how however whence whenever where whereby whereever wherein whereof why

passing object by reference in C++

One thing that I have to add is that there is no reference in C.

Secondly, this is the language syntax convention. & - is an address operator but it also mean a reference - all depends on usa case

If there was some "reference" keyword instead of & you could write

int CDummy::isitme (reference CDummy param)

but this is C++ and we should accept it advantages and disadvantages...

Compare two Lists for differences

.... but how do we find the equivalent class in the second List to pass to the method below;

This is your actual problem; you must have at least one immutable property, a id or something like that, to identify corresponding objects in both lists. If you do not have such a property you, cannot solve the problem without errors. You can just try to guess corresponding objects by searching for minimal or logical changes.

If you have such an property, the solution becomes really simple.

   listA, listB,
   a => a.Id, b => b.Id,
   (a, b) => CompareTwoClass_ReturnDifferences(a, b))

thanks to you both danbruc and Noldorin for your feedback. both Lists will be the same length and in the same order. so the method above is close, but can you modify this method to pass the enum.Current to the method i posted above?

Now I am confused ... what is the problem with that? Why not just the following?

for (Int32 i = 0; i < Math.Min(listA.Count, listB.Count); i++)
    yield return CompareTwoClass_ReturnDifferences(listA[i], listB[i]);

The Math.Min() call may even be left out if equal length is guaranted.

Noldorin's implementation is of course smarter because of the delegate and the use of enumerators instead of using ICollection.

error Failed to build iOS project. We ran "xcodebuild" command but it exited with error code 65

In my case everything solved after re-cloning the repo and launching it again.

Setup: Xcode 12.4 Mac M1

grep regex whitespace behavior

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


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


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

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

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

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

facebook: permanent Page Access Token?

If you are requesting only page data, then you can use a page access token. You will only have to authorize the user once to get the user access token; extend it to two months validity then request the token for the page. This is all explained in Scenario 5. Note, that the acquired page access token is only valid for as long as the user access token is valid.

How to JOIN three tables in Codeigniter

try this

In your model

If u want get all album data use

  function get_all_album_data() {

    $this->db->select ( '*' ); 
    $this->db->from ( 'Album' );
    $this->db->join ( 'Category', 'Category.cat_id = Album.cat_id' , 'left' );
    $this->db->join ( 'Soundtrack', 'Soundtrack.album_id = Album.album_id' , 'left' );
    $query = $this->db->get ();
    return $query->result ();

if u want to get specific album data use

  function get_album_data($album_id) {

    $this->db->select ( '*' ); 
    $this->db->from ( 'Album' );
    $this->db->join ( 'Category', 'Category.cat_id = Album.cat_id' , 'left' );
    $this->db->join ( 'Soundtrack', 'Soundtrack.album_id = Album.album_id' , 'left' );
    $this->db->where ( 'Album.album_id', $album_id);
    $query = $this->db->get ();
    return $query->result ();

npm - "Can't find Python executable "python", you can set the PYTHON env variable."

Just run below command with admin access

npm install --global --production windows-build-tools

Javascript array declaration: new Array(), new Array(3), ['a', 'b', 'c'] create arrays that behave differently

Arrays in JS have two types of properties:

Regular elements and associative properties (which are nothing but objects)

When you define a = new Array(), you are defining an empty array. Note that there are no associative objects yet

When you define b = new Array(2), you are defining an array with two undefined locations.

In both your examples of 'a' and 'b', you are adding associative properties i.e. objects to these arrays.

console.log (a) or console.log(b) prints the array elements i.e. [] and [undefined, undefined] respectively. But since a1/a2 and b1/b2 are associative objects inside their arrays, they can be logged only by console.log(a.a1, a.a2) kind of syntax

How do I start a process from C#?

Use the Process class. The MSDN documentation has an example how to use it.

SSRS custom number format

You can use


Possible to extend types in Typescript?

You can also do:

export type UserEvent = Event & { UserId: string; };

Convert Python dict into a dataframe

d = {'Date': list(yourDict.keys()),'Date_Values': list(yourDict.values())}
df = pandas.DataFrame(data=d)

If you don't encapsulate yourDict.keys() inside of list() , then you will end up with all of your keys and values being placed in every row of every column. Like this:

Date \ 0 (2012-06-08, 2012-06-09, 2012-06-10, 2012-06-1...
1 (2012-06-08, 2012-06-09, 2012-06-10, 2012-06-1...
2 (2012-06-08, 2012-06-09, 2012-06-10, 2012-06-1...
3 (2012-06-08, 2012-06-09, 2012-06-10, 2012-06-1...
4 (2012-06-08, 2012-06-09, 2012-06-10, 2012-06-1...

But by adding list() then the result looks like this:

Date Date_Values 0 2012-06-08 388 1 2012-06-09 388 2 2012-06-10 388 3 2012-06-11 389 4 2012-06-12 389 ...

How to do a redirect to another route with react-router?

The simplest solution is:

import { Redirect } from 'react-router';

<Redirect to='/componentURL' />

Test if characters are in a string

Use grep or grepl but be aware of whether or not you want to use regular expressions.

By default, grep and related take a regular expression to match, not a literal substring. If you're not expecting that, and you try to match on an invalid regex, it doesn't work:

> grep("[", "abc[")
Error in grep("[", "abc[") : 
  invalid regular expression '[', reason 'Missing ']''

To do a true substring test, use fixed = TRUE.

> grep("[", "abc[", fixed = TRUE)
[1] 1

If you do want regex, great, but that's not what the OP appears to be asking.

How to get summary statistics by group

after 5 long years I'm sure not much attention is going to be received for this answer, But still to make all options complete, here is the one with data.table

setDT(df)[ , list(mean_gr = mean(dt), sum_gr = sum(dt)) , by = .(group)]
#   group mean_gr sum_gr
#1:     A      61    244
#2:     B      66    396
#3:     C      68    408
#4:     D      61    488 

Access a JavaScript variable from PHP

I'm looking at this and thinking, if you can only get variables into php in a form, why not just make a form and put a hidden input in the thing so it doesn't show on screen, and then put the value from your javascript into the hidden input and POST that into the php? It would sure be a lot less hassle than some of this other stuff right?

how to show lines in common (reverse diff)?

Easiest way to do is :

awk 'NR==FNR{a[$1]++;next} a[$1] ' file1 file2

Files are not necessary to be sorted.

Android - Spacing between CheckBox and text

All you have to do to overcome this problem is to add android:singleLine="true" to the checkBox in your android xml layout:


and nothing special will be added programmatically.

How to pass an object into a state using UI-router?


        .state('app.example1', {
                url: '/example',
                views: {
                    'menuContent': {
                        templateUrl: 'templates/example.html',
                        controller: 'ExampleCtrl'
            .state('app.example2', {
                url: '/example2/:object',
                views: {
                    'menuContent': {
                        templateUrl: 'templates/example2.html',
                        controller: 'Example2Ctrl'


.controller('ExampleCtrl', function ($state, $scope, UserService) {

        $scope.goExample2 = function (obj) {

            $state.go("app.example2", {object: JSON.stringify(obj)});

    .controller('Example2Ctrl', function ($state, $scope, $stateParams) {



Ineligible Devices section appeared in Xcode 6.x.x

My solution was that I had recently upgraded my iOS device to 8.3 and Xcode still didn't recognize it. The fix was to simply upgrade Xcode to 6.3 :)

What is process.env.PORT in Node.js?

In some scenarios, port can only be designated by the environment and is saved in a user environment variable. Below is how node.js apps work with it.

The process object is a global that provides information about, and control over, the current Node.js process. As a global, it is always available to Node.js applications without using require().

The process.env property returns an object containing the user environment.

An example of this object looks like:

  TERM: 'xterm-256color',
  SHELL: '/usr/local/bin/bash',
  USER: 'maciej',
  PATH: '~/.bin/:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin',
  PWD: '/Users/maciej',
  EDITOR: 'vim',
  SHLVL: '1',
  HOME: '/Users/maciej',
  LOGNAME: 'maciej',
  _: '/usr/local/bin/node'

For example,

terminal: set a new user environment variable, not permanently

export MY_TEST_PORT=9999

app.js: read the new environment variable from node app


terminal: run the node app and get the value

$ node app.js