Programs & Examples On #Simplebutton

Center HTML Input Text Field Placeholder

The HTML5 placeholder element can be styled for those browsers that accept the element, but in diferent ways, as you can see here:

But I don't believe that text-align will be interpreted by the browsers. At least on Chrome, this attribute is ignored. But you can always change other things, like color, font-size, font-family etc. I suggest you rethinking your design whether possible to remove this center behavior.


If you really want this text centered, you can always use some jQuery code or plugin to simulate the placeholder behavior. Here is a sample of it:

This way the style will work:

input.placeholder {
    text-align: center;

How to get a URL parameter in Express?

You can do something like req.param('tagId')

How to drop columns using Rails migration

Clear & Simple Instructions for Rails 5 & 6

  • WARNING: You will lose data if you remove a column from your database. To proceed, see below:
  • Warning: the below instructions are for trivial migrations. For complex migrations with e.g. millions and millions of rows, you will have to account for the possibility of failures, you will also have to think about how to optimise your migrations so that they run swiftly, and the possibility that users will use your app while the migration process is occurring. If you have multiple databases, or if anything is remotely complicated, then don't blame me if anything goes wrong!

1. Create a migration

Run the following command in your terminal:

rails generate migration remove_fieldname_from_tablename fieldname:fieldtype

Note: the table name should be in plural form as per rails convention.


In my case I want to remove the accepted column (a boolean value) from the quotes table:

rails g migration RemoveAcceptedFromQuotes accepted:boolean

See the documentation re: a convention when adding/removing fields to a table:

There is a special syntactic shortcut to generate migrations that add fields to a table.

rails generate migration add_fieldname_to_tablename fieldname:fieldtype

2. Check the migration

# db/migrate/20190122035000_remove_accepted_from_quotes.rb
class RemoveAcceptedFromQuotes < ActiveRecord::Migration[5.2]
  # with rails 5.2 you don't need to add a separate "up" and "down" method.
  def change
    remove_column :quotes, :accepted, :boolean

3. Run the migration

rake db:migrate or rails db:migrate (they're both the same)

....And then you're off to the races!

Maven Unable to locate the Javac Compiler in:

In Eclipse, actions like importing Maven projects or invoking "Update Sources" runs in the same JVM in which Eclipse is running. If that JVM comes from JRE that isn’t part of JDK, there would be no Java compiler (the tools.jar).

So to launch Maven from within Eclipse, JRE used for launch also need to come from JDK. By default Eclipse registers JRE it is started in, but this can be configured on "Window / Preferences… / Java / Installed JREs" preference page as mentioned above by Parthasarathy

Alternatively you can specify compilerId in the pom.xml, so Maven won’t be looking for JDK when compiling Java code:


Meaning of = delete after function declaration

= delete is a feature introduce in C++11. As per =delete it will not allowed to call that function.

In detail.

Suppose in a class.

Class ABC{
 Int d;
  ABC& operator= (const ABC& obj) =delete


While calling this function for obj assignment it will not allowed. Means assignment operator is going to restrict to copy from one object to another.

How do I install TensorFlow's tensorboard?

The steps to install Tensorflow are here:

For example, on Linux for CPU-only (no GPU), you would type this command:

pip install -U pip
pip install tensorflow

Since TensorFlow depends on TensorBoard, running the following command should not be necessary:

pip install tensorboard

How to set limits for axes in ggplot2 R plots?

Basically you have two options

scale_x_continuous(limits = c(-5000, 5000))


coord_cartesian(xlim = c(-5000, 5000)) 

Where the first removes all data points outside the given range and the second only adjusts the visible area. In most cases you would not see the difference, but if you fit anything to the data it would probably change the fitted values.

You can also use the shorthand function xlim (or ylim), which like the first option removes data points outside of the given range:

+ xlim(-5000, 5000)

For more information check the description of coord_cartesian.

The RStudio cheatsheet for ggplot2 makes this quite clear visually. Here is a small section of that cheatsheet:

enter image description here

Distributed under CC BY.

What does "to stub" mean in programming?

Stub is a function definition that has correct function name, the correct number of parameters and produces dummy result of the correct type.

It helps to write the test and serves as a kind of scaffolding to make it possible to run the examples even before the function design is complete

How to convert string to integer in PowerShell

Once you have selected the highest value, which is "12" in my example, you can then declare it as integer and increment your value:

$FileList = "1", "2", "11"
$foldername = [int]$FileList[2] + 1

nginx - client_max_body_size has no effect

I had a similar problem recently and found out, that client_max_body_size 0; can solve such an issue. This will set client_max_body_size to no limit. But the best practice is to improve your code, so there is no need to increase this limit.

Why does Math.Round(2.5) return 2 instead of 3?

Since Silverlight doesn't support the MidpointRounding option you have to write your own. Something like:

public double RoundCorrect(double d, int decimals)
    double multiplier = Math.Pow(10, decimals);

    if (d < 0)
        multiplier *= -1;

    return Math.Floor((d * multiplier) + 0.5) / multiplier;


For the examples including how to use this as an extension see the post: .NET and Silverlight Rounding

Getting the HTTP Referrer in ASP.NET



The Request.UrlReferer property will throw a System.UriFormatException if the referer HTTP header is malformed (which can happen since it is not usually under your control).

Therefore, the Request.UrlReferer property is not 100% reliable - it may contain data that cannot be parsed into a Uri class. To ensure the value is always readable, use Request.Headers["Referrer"] instead.

As for using Request.ServerVariables as others here have suggested, per MSDN:

Request.ServerVariables Collection

The ServerVariables collection retrieves the values of predetermined environment variables and request header information.

Request.Headers Property

Gets a collection of HTTP headers.

Request.Headers is a better choice than Request.ServerVariables, since Request.ServerVariables contains all of the environment variables as well as the headers, where Request.Headers is a much shorter list that only contains the headers.

So the most reliable solution is to use the Request.Headers collection to read the value directly. Do heed Microsoft's warnings about HTML encoding the value if you are going to display it on a form, though.

UIView bottom border?

There is also improved code with remove border functionality. Based on confile answer.

import UIKit

enum viewBorder: String {
    case Left = "borderLeft"
    case Right = "borderRight"
    case Top = "borderTop"
    case Bottom = "borderBottom"

extension UIView {

    func addBorder(vBorder: viewBorder, color: UIColor, width: CGFloat) {
        let border = CALayer()
        border.backgroundColor = color.CGColor = vBorder.rawValue
        switch vBorder {
            case .Left:
                border.frame = CGRectMake(0, 0, width, self.frame.size.height)
            case .Right:
                border.frame = CGRectMake(self.frame.size.width - width, 0, width, self.frame.size.height)
            case .Top:
                border.frame = CGRectMake(0, 0, self.frame.size.width, width)
            case .Bottom:
                border.frame = CGRectMake(0, self.frame.size.height - width, self.frame.size.width, width)

    func removeBorder(border: viewBorder) {
        var layerForRemove: CALayer?
        for layer in self.layer.sublayers! {
            if == border.rawValue {
                layerForRemove = layer
        if let layer = layerForRemove {


Update: Swift 3

import UIKit

enum ViewBorder: String {
    case left, right, top, bottom

extension UIView {

    func add(border: ViewBorder, color: UIColor, width: CGFloat) {
        let borderLayer = CALayer()
        borderLayer.backgroundColor = color.cgColor = border.rawValue
        switch border {
        case .left:
            borderLayer.frame = CGRect(x: 0, y: 0, width: width, height: self.frame.size.height)
        case .right:
            borderLayer.frame = CGRect(x: self.frame.size.width - width, y: 0, width: width, height: self.frame.size.height)
        case .top:
            borderLayer.frame = CGRect(x: 0, y: 0, width: self.frame.size.width, height: width)
        case .bottom:
            borderLayer.frame = CGRect(x: 0, y: self.frame.size.height - width, width: self.frame.size.width, height: width)

    func remove(border: ViewBorder) {
        guard let sublayers = self.layer.sublayers else { return }
        var layerForRemove: CALayer?
        for layer in sublayers {
            if == border.rawValue {
                layerForRemove = layer
        if let layer = layerForRemove {


Getting a random value from a JavaScript array

I've found a way around the top answer's complications, just by concatenating the variable rand to another variable that allows that number to be displayed inside the calling of myArray[];. By deleting the new array created and toying around with it's complications, I've come up with a working solution:

<!DOCTYPE html>

<p id="demo"></p>


var myArray = ['January', 'February', 'March', 'April', 'May'];    

var rand = Math.floor(Math.random() * myArray.length);

var concat = myArray[rand];

function random() {
   document.getElementById("demo").innerHTML = (concat);

<button onClick="random();">
Working Random Array generator


No input file specified

GoDaddy is currently (Feb '13) supporting modification of FastCGI for some accounts using PHP 5.2.x or earlier. See GoDaddy article "Disabling FastCGI in Your Hosting Account".
(In my case, this is apparently necessary to help get the current version of LimeSurvey (2.0) towards a running state.)

check if "it's a number" function in Oracle

I'm against using when others so I would use (returning an "boolean integer" due to SQL not suppporting booleans)

create or replace function is_number(param in varchar2) return integer
   ret number;
    ret := to_number(param);
    return 1; --true
    when invalid_number then return 0;

In the SQL call you would use something like

select case when ( is_number( and ( >'0') ) 
            then 'Is a number greater than 0' 
            else 'it is not a number or is not greater than 0' 
       end as valuetype  
  from table myTable

How to change the font and font size of an HTML input tag?

in your css :

 #txtComputer {
      font-size: 24px;

You can style an input entirely (background, color, etc.) and even use the hover event.

Send and Receive a file in socket programming in Linux with C/C++ (GCC/G++)

The most portable solution is just to read the file in chunks, and then write the data out to the socket, in a loop (and likewise, the other way around when receiving the file). You allocate a buffer, read into that buffer, and write from that buffer into your socket (you could also use send and recv, which are socket-specific ways of writing and reading data). The outline would look something like this:

while (1) {
    // Read data into buffer.  We may not have enough to fill up buffer, so we
    // store how many bytes were actually read in bytes_read.
    int bytes_read = read(input_file, buffer, sizeof(buffer));
    if (bytes_read == 0) // We're done reading from the file

    if (bytes_read < 0) {
        // handle errors

    // You need a loop for the write, because not all of the data may be written
    // in one call; write will return how many bytes were written. p keeps
    // track of where in the buffer we are, while we decrement bytes_read
    // to keep track of how many bytes are left to write.
    void *p = buffer;
    while (bytes_read > 0) {
        int bytes_written = write(output_socket, p, bytes_read);
        if (bytes_written <= 0) {
            // handle errors
        bytes_read -= bytes_written;
        p += bytes_written;

Make sure to read the documentation for read and write carefully, especially when handling errors. Some of the error codes mean that you should just try again, for instance just looping again with a continue statement, while others mean something is broken and you need to stop.

For sending the file to a socket, there is a system call, sendfile that does just what you want. It tells the kernel to send a file from one file descriptor to another, and then the kernel can take care of the rest. There is a caveat that the source file descriptor must support mmap (as in, be an actual file, not a socket), and the destination must be a socket (so you can't use it to copy files, or send data directly from one socket to another); it is designed to support the usage you describe, of sending a file to a socket. It doesn't help with receiving the file, however; you would need to do the loop yourself for that. I cannot tell you why there is a sendfile call but no analogous recvfile.

Beware that sendfile is Linux specific; it is not portable to other systems. Other systems frequently have their own version of sendfile, but the exact interface may vary (FreeBSD, Mac OS X, Solaris).

In Linux 2.6.17, the splice system call was introduced, and as of 2.6.23 is used internally to implement sendfile. splice is a more general purpose API than sendfile. For a good description of splice and tee, see the rather good explanation from Linus himself. He points out how using splice is basically just like the loop above, using read and write, except that the buffer is in the kernel, so the data doesn't have to transferred between the kernel and user space, or may not even ever pass through the CPU (known as "zero-copy I/O").

Use PHP to convert PNG to JPG with compression?

function createThumbnail($imageDirectory, $imageName, $thumbDirectory, $thumbWidth) {
    $explode = explode(".", $imageName);
    $filetype = $explode[1];

    if ($filetype == 'jpg') {
        $srcImg = imagecreatefromjpeg("$imageDirectory/$imageName");
    } else
    if ($filetype == 'jpeg') {
        $srcImg = imagecreatefromjpeg("$imageDirectory/$imageName");
    } else
    if ($filetype == 'png') {
        $srcImg = imagecreatefrompng("$imageDirectory/$imageName");
    } else
    if ($filetype == 'gif') {
        $srcImg = imagecreatefromgif("$imageDirectory/$imageName");

    $origWidth = imagesx($srcImg);
    $origHeight = imagesy($srcImg);

    $ratio = $origWidth / $thumbWidth;
    $thumbHeight = $origHeight / $ratio;

    $thumbImg = imagecreatetruecolor($thumbWidth, $thumbHeight);
    imagecopyresized($thumbImg, $srcImg, 0, 0, 0, 0, $thumbWidth, $thumbHeight, $origWidth, $origHeight);

    if ($filetype == 'jpg') {
        imagejpeg($thumbImg, "$thumbDirectory/$imageName");
    } else
    if ($filetype == 'jpeg') {
        imagejpeg($thumbImg, "$thumbDirectory/$imageName");
    } else
    if ($filetype == 'png') {
        imagepng($thumbImg, "$thumbDirectory/$imageName");
    } else
    if ($filetype == 'gif') {
        imagegif($thumbImg, "$thumbDirectory/$imageName");

This is a very good thumbnail script =) Here's an example:

$path = The path to the folder where the original picture is. $name = The filename of the file you want to make a thumbnail of. $thumbpath = The path to the directory where you want the thumbnail to be saved into. $maxwidth = the maximum width of the thumbnail in PX eg. 100 (wich will be 100px).

createThumbnail($path, $name, $thumbpath, $maxwidth);

What is Shelving in TFS?

I come across this all the time, so supplemental information regarding branches:

If you're working with multiple branches, shelvesets are tied to the specific branch in which you created them. So, if you let a changeset rust on the shelf for too long and have to unshelve to a different branch, then you have to do that with the July release of the power tools.

tfpt unshelve /migrate

How to get input text length and validate user in javascript

JavaScript validation is not secure as anybody can change what your script does in the browser. Using it for enhancing the visual experience is ok though.

var textBox = document.getElementById("myTextBox");
var textLength = textBox.value.length;
if(textLength > 5)
    //red = "#FF0000";
    //green = "#00FF00";

How to write both h1 and h2 in the same line?

<h1 style="text-align: left; float: left;">Text 1</h1>
<h2 style="text-align: right; float: right; display: inline;">Text 2</h2>
<hr style="clear: both;" />

Hope this helps!

Export data from Chrome developer tool

I had same issue for which I came here. With some trials, I figured out for copying multiple pages of chrome data as in the question I zoomed out till I got all the data in one page, that is, without scroll, with very small font size. Now copy and paste that in excel which copies all the records and in normal font. This is good for few pages of data I think.

kill -3 to get java thread dump

There is a way to redirect JVM thread dump output on break signal to separate file with LogVMOutput diagnostic option:

-XX:+UnlockDiagnosticVMOptions -XX:+LogVMOutput -XX:LogFile=jvm.log

How to align td elements in center

Give a style inside the td element or in your scss file, like this:


How to find EOF through fscanf?

while (fscanf(input,"%s",arr) != EOF && count!=7) {

How to get current screen width in CSS?

this can be achieved with the css calc() operator

@media screen and (min-width: 480px) {
    body {
        background-color: lightgreen;
        zoom:calc(100% / 480);

How do I execute a stored procedure in a SQL Agent job?

As Marc says, you run it exactly like you would from the command line. See Creating SQL Server Agent Jobs on MSDN.

Why I get 'list' object has no attribute 'items'?

result_list = [int(v) for k,v in qs[0].items()]

qs is a list, qs[0] is the dict which you want!

How do I enter a multi-line comment in Perl?

I found it. Perl has multi-line comments:


use strict;

use warnings;

=for comment

Example of multiline comment.

Example of multiline comment.


print "Multi Line Comment Example \n";

Hide axis and gridlines Highcharts

If you doesn't want to touch the config object, you just hide the grid by css:

.chart-container .highcharts-grid {
   display: none;

How can I align button in Center or right using IONIC framework?

To use center alignment in ionic app code itself, you can use the following code:

<ion-row center>  
 <ion-col text-center>   
  <button ion-button>Search</button>  

To use right alignment in ionic app code itself, you can use the following code:

<ion-row right>  
 <ion-col text-right>   
  <button ion-button>Search</button>  

How to populate HTML dropdown list with values from database

Below code is nice.. It was given by somebody else named aaronbd in this forum


$conn = new mysqli('localhost', 'username', 'password', 'database') 
or die ('Cannot connect to db');

    $result = $conn->query("select id, name from table");

    echo "<html>";
    echo "<body>";
    echo "<select name='id'>";

    while ($row = $result->fetch_assoc()) {

                  unset($id, $name);
                  $id = $row['id'];
                  $name = $row['name']; 
                  echo '<option value="'.$id.'">'.$name.'</option>';


    echo "</select>";
    echo "</body>";
    echo "</html>";

How to download source in ZIP format from GitHub?

In chrome, if you hover your cursor on Download ZIP it will give you the link at the bottom of the browser

enter image description here

How to display activity indicator in middle of the iphone screen?

For Swift 3 you can use the following:

 func setupSpinner(){
    spinner = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 40, height:40))
    spinner.color = UIColor(Colors.Accent) = CGPoint(x:UIScreen.main.bounds.size.width / 2, y:UIScreen.main.bounds.size.height / 2)
    spinner.hidesWhenStopped = true

Web API Routing - api/{controller}/{action}/{id} "dysfunctions" api/{controller}/{id}

The route engine uses the same sequence as you add rules into it. Once it gets the first matched rule, it will stop checking other rules and take this to search for controller and action.

So, you should:

  1. Put your specific rules ahead of your general rules(like default), which means use RouteTable.Routes.MapHttpRoute to map "WithActionApi" first, then "DefaultApi".

  2. Remove the defaults: new { id = System.Web.Http.RouteParameter.Optional } parameter of your "WithActionApi" rule because once id is optional, url like "/api/{part1}/{part2}" will never goes into "DefaultApi".

  3. Add an named action to your "DefaultApi" to tell the route engine which action to enter. Otherwise once you have more than one actions in your controller, the engine won't know which one to use and throws "Multiple actions were found that match the request: ...". Then to make it matches your Get method, use an ActionNameAttribute.

So your route should like this:

// Map this rule first

    new { action="DefaultAction", id = System.Web.Http.RouteParameter.Optional }

And your controller:

[ActionName("DefaultAction")] //Map Action and you can name your method with any text
public string Get(int id)
    return "object of id id";

public IEnumerable<string> ByCategoryId(int id)
    return new string[] { "byCategory1", "byCategory2" };

How to replace NA values in a table for selected columns

This is now trivial in tidyr with replace_na(). The function appears to work for data.tables as well as data.frames:

tidyr::replace_na(x, list(a=0, b=0))

Get IFrame's document, from JavaScript in main document

In case you get a cross-domain error:

If you have control over the content of the iframe - that is, if it is merely loaded in a cross-origin setup such as on Amazon Mechanical Turk - you can circumvent this problem with the <body onload='my_func(my_arg)'> attribute for the inner html.

For example, for the inner html, use the this html parameter (yes - this is defined and it refers to the parent window of the inner body element):

<body onload='changeForm(this)'>

In the inner html :

    function changeForm(window) {
        console.log('inner window loaded: do whatever you want with the inner html');
        window.document.getElementById('mturk_form').style.display = 'none';

how to bind img src in angular 2 in ngFor?

Angular 2 and Angular 4 

In a ngFor loop it must be look like this:

<div class="column" *ngFor="let u of events ">
                <div class="thumb">
                    <img src="assets/uploads/{{u.image}}">
                <div class="info">
                    <img src="assets/uploads/{{u.image}}">

How to implement a Map with multiple keys?

I recommend something like this:

    public class MyMap {

      Map<Object, V> map = new HashMap<Object, V>();

      public V put(K1 key,V value){
        return map.put(key, value);

      public V put(K2 key,V value){
        return map.put(key, value);

      public V get(K1 key){    
        return map.get(key);

      public V get(K2 key){    
        return map.get(key);

      //Same for conatains


Then you can use it like:
myMap.put(k1,value) or myMap.put(k2,value)

Advantages: It is simple, enforces type safety, and doesn't store repeated data (as the two maps solutions do, though still store duplicate values).
Drawbacks: Not generic.

How to get the caller's method name in the called method?

Shorter version:

import inspect

def f1(): f2()

def f2():
    print 'caller name:', inspect.stack()[1][3]


(with thanks to @Alex, and Stefaan Lippen)

javascript regex : only english letters allowed

let res = /^[a-zA-Z]+$/.test('sfjd');

Note: If you have any punctuation marks or anything, those are all invalid too. Dashes and underscores are invalid. \w covers a-zA-Z and some other word characters. It all depends on what you need specifically.

How do I update the password for Git?

do these steps in Terminal:

  1. Delete current password saved in your Mac

    git config --global --unset user.password
  2. Add your new password by using this command, replace with your new password:

    git config --global --add user.password <new_pass>

How to connect mySQL database using C++

I had to include -lmysqlcppconn to my build in order to get it to work.


CONVERT(DATA_TYPE , Your_Column) is the syntax for CONVERT method in SQL. From this convert function we can convert the data of the Column which is on the right side of the comma (,) to the data type in the left side of the comma (,) Please see below example.


How can I compare two dates in PHP?

You can convert the dates into UNIX timestamps and compare the difference between them in seconds.

$dateTimestamp1 = strtotime($today_date);
$dateTimestamp2 = strtotime($entered_date);
$diff= $dateTimestamp1-$dateTimestamp2;
//echo $diff;
if ($diff<=0)
     echo "Enter a valid date";

How to find out if a Python object is a string?

I found this ans more pythonic:

if type(aObject) is str:
    #do your stuff here

since type objects are singleton, is can be used to do the compare the object to the str type

CSS endless rotation animation

Working nice:

#test {_x000D_
    width: 11px;_x000D_
    height: 14px;_x000D_
    background: url('data:image/gif;base64,R0lGOD lhCwAOAMQfAP////7+/vj4+Hh4eHd3d/v7+/Dw8HV1dfLy8ubm5vX19e3t7fr 6+nl5edra2nZ2dnx8fMHBwYODg/b29np6eujo6JGRkeHh4eTk5LCwsN3d3dfX 13Jycp2dnevr6////yH5BAEAAB8ALAAAAAALAA4AAAVq4NFw1DNAX/o9imAsB tKpxKRd1+YEWUoIiUoiEWEAApIDMLGoRCyWiKThenkwDgeGMiggDLEXQkDoTh CKNLpQDgjeAsY7MHgECgx8YR8oHwNHfwADBACGh4EDA4iGAYAEBAcQIg0Dk gcEIQA7');_x000D_
@-webkit-keyframes rotating {_x000D_
        -webkit-transform: rotate(0deg);_x000D_
        -webkit-transform: rotate(360deg);_x000D_
.rotating {_x000D_
    -webkit-animation: rotating 2s linear infinite;_x000D_
<div id='test' class='rotating'></div>

How do I improve ASP.NET MVC application performance?

Use the latest version of Task Parallel Library (TPL), according to .Net version. Have to choose the correct modules of TPL for different purposes.

How can I make robocopy silent in the command line except for progress?

I did it by using the following options:

/njh /njs /ndl /nc /ns

Note that the file name still displays, but that's fine for me.

For more information on robocopy, go to

Combine two tables that have no common fields


select * from table 1 left join table2 as t on 1 = 1;

This will bring all the columns from both the table.

Excel date to Unix timestamp

Here's my ultimate answer to this.

Also apparently javascript's new Date(year, month, day) constructor doesn't account for leap seconds too.

// Parses an Excel Date ("serial") into a
// corresponding javascript Date in UTC+0 timezone.
// Doesn't account for leap seconds.
// Therefore is not 100% correct.
// But will do, I guess, since we're
// not doing rocket science here.
// "If you need to calculate dates in your spreadsheets,
//  Excel uses its own unique system, which it calls Serial Numbers".
lib.parseExcelDate = function (excelSerialDate) {
  // "Excel serial date" is just
  // the count of days since `01/01/1900`
  // (seems that it may be even fractional).
  // The count of days elapsed
  // since `01/01/1900` (Excel epoch)
  // till `01/01/1970` (Unix epoch).
  // Accounts for leap years
  // (19 of them, yielding 19 extra days).
  const daysBeforeUnixEpoch = 70 * 365 + 19;

  // An hour, approximately, because a minute
  // may be longer than 60 seconds, see "leap seconds".
  const hour = 60 * 60 * 1000;

  // "In the 1900 system, the serial number 1 represents January 1, 1900, 12:00:00 a.m.
  //  while the number 0 represents the fictitious date January 0, 1900".
  // These extra 12 hours are a hack to make things
  // a little bit less weird when rendering parsed dates.
  // E.g. if a date `Jan 1st, 2017` gets parsed as
  // `Jan 1st, 2017, 00:00 UTC` then when displayed in the US
  // it would show up as `Dec 31st, 2016, 19:00 UTC-05` (Austin, Texas).
  // That would be weird for a website user.
  // Therefore this extra 12-hour padding is added
  // to compensate for the most weird cases like this
  // (doesn't solve all of them, but most of them).
  // And if you ask what about -12/+12 border then
  // the answer is people there are already accustomed
  // to the weird time behaviour when their neighbours
  // may have completely different date than they do.
  // `Math.round()` rounds all time fractions
  // smaller than a millisecond (e.g. nanoseconds)
  // but it's unlikely that an Excel serial date
  // is gonna contain even seconds.
  return new Date(Math.round((excelSerialDate - daysBeforeUnixEpoch) * 24 * hour) + 12 * hour);

Adding a caption to an equation in LaTeX

As in this forum post by Gonzalo Medina, a third way may be:




Some text

\caption{Caption of the equation}

Some other text

More details of the commands used from package caption: here.

A screenshot of the output of the above code:

screenshot of output

Searching a list of objects in Python

filter(lambda x: x.n == 5, myList)

How to position a DIV in a specific coordinates?

I cribbed this and added the 'px'; Works very well.

function getOffset(el) {
  el = el.getBoundingClientRect();
  return {
    left: (el.right + window.scrollX ) +'px',
    top: ( + window.scrollY ) +'px'
to call: //Gets it to the right side = getOffset(othis).top ; = getOffset(othis).left ; 

How to stop text from taking up more than 1 line?

Just to be crystal clear, this works nicely with paragraphs and headers etc. You just need to specify display: block.

For instance:

<h5 style="display: block; text-overflow: ellipsis; white-space: nowrap; overflow: hidden">
  This is a really long title, but it won't exceed the parent width

(forgive the inline styles)

Cannot declare instance members in a static class in C#

It says what it means:

make your class non-static:

public class employee
  NameValueCollection appSetting = ConfigurationManager.AppSettings;    

or the member static:

public static class employee
  static NameValueCollection appSetting = ConfigurationManager.AppSettings;    

Generator expressions vs. list comprehensions

List comprehensions are eager but generators are lazy.

In list comprehensions all objects are created right away, it takes longer to create and return the list. In generator expressions, object creation is delayed until request by next(). Upon next() generator object is created and returned immediately.

Iteration is faster in list comprehensions because objects are already created.

If you iterate all the elements in list comprehension and generator expression, time performance is about the same. Even though generator expression return generator object right away, it does not create all the elements. Everytime you iterate over a new element, it will create and return it.

But if you do not iterate through all the elements generator are more efficient. Let's say you need to create a list comprehensions that contains millions of items but you are using only 10 of them. You still have to create millions of items. You are just wasting time for making millions of calculations to create millions of items to use only 10. Or if you are making millions of api requests but end up using only 10 of them. Since generator expressions are lazy, it does not make all the calculations or api calls unless it is requested. In this case using generator expressions will be more efficient.

In list comprehensions entire collection is loaded to the memory. But generator expressions, once it returns a value to you upon your next() call, it is done with it and it does not need to store it in the memory any more. Only a single item is loaded to the memory. If you are iterating over a huge file in disk, if file is too big you might get memory issue. In this case using generator expression is more efficient.

UNIX export command

When you execute a program the child program inherits its environment variables from the parent. For instance if $HOME is set to /root in the parent then the child's $HOME variable is also set to /root.

This only applies to environment variable that are marked for export. If you set a variable at the command-line like

$ FOO="bar"

That variable will not be visible in child processes. Not unless you export it:

$ export FOO

You can combine these two statements into a single one in bash (but not in old-school sh):

$ export FOO="bar"

Here's a quick example showing the difference between exported and non-exported variables. To understand what's happening know that sh -c creates a child shell process which inherits the parent shell's environment.

$ FOO=bar
$ sh -c 'echo $FOO'

$ export FOO
$ sh -c 'echo $FOO'

Note: To get help on shell built-in commands use help export. Shell built-ins are commands that are part of your shell rather than independent executables like /bin/ls.

HTML5 image icon to input placeholder

I don't know whether there's a better answer out there as time goes by but this is simple and it works;

input[type='email'] {
  background: white url(images/mail.svg) no-repeat ;
input[type='email']:focus {
  background-image: none;

Style it up to suit.

Get the item doubleclick event of listview

In the ListBox DoubleClick event get the selecteditem(s) member of the listbox, and there you are.

void ListBox1DoubleClick(object sender, EventArgs e)

Setting value of active workbook in Excel VBA

This is all you need

Set wbOOR = ActiveWorkbook

How to get UTF-8 working in Java webapps?

In case you have specified in connection pool (mysql-ds.xml), in your Java code you can open the connection as follows:

DriverManager.registerDriver(new com.mysql.jdbc.Driver());
Connection conn = DriverManager.getConnection(
    "Myuser", "mypass");

Insert the same fixed value into multiple rows

What you're actually doing is adding rows. To update the content of existing rows use the UPDATE statement:

UPDATE table SET table_column = 'test';

Comparison of DES, Triple DES, AES, blowfish encryption for data

enter image description here

DES is the old "data encryption standard" from the seventies.

Textarea Auto height

It can be achieved using JS. Here is a 'one-line' solution using elastic.js:


Updated: Seems like elastic.js is not there anymore, but if you are looking for an external library, I can recommend autosize.js by Jack Moore. This is the working example:

textarea#note {_x000D_
 padding:15px 15px 30px;_x000D_
 border:1px solid #F7E98D;_x000D_
 font:13px Tahoma, cursive;_x000D_
 transition:box-shadow 0.5s ease;_x000D_
 box-shadow:0 4px 6px rgba(0,0,0,0.1);_x000D_
 background:linear-gradient(#F9EFAF, #F7E98D);_x000D_
 background:-o-linear-gradient(#F9EFAF, #F7E98D);_x000D_
 background:-ms-linear-gradient(#F9EFAF, #F7E98D);_x000D_
 background:-moz-linear-gradient(#F9EFAF, #F7E98D);_x000D_
 background:-webkit-linear-gradient(#F9EFAF, #F7E98D);_x000D_
<script src=""></script>_x000D_
<textarea id="note">Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.</textarea>

Check this similar topics too:

Autosizing textarea using Prototype

Textarea to resize based on content length

Creating a textarea with auto-resize

Copying PostgreSQL database to another server

If you are looking to migrate between versions (eg you updated postgres and have 9.1 running on localhost:5432 and 9.3 running on localhost:5434) you can run:

pg_dumpall -p 5432 -U myuser91 | psql -U myuser94 -d postgres -p 5434

Check out the migration docs.

Where do I find some good examples for DDD?

Not source projects per say but I stumbled upon which has a few good videos that cover DDD quite well (requires flash):

I found these much more helpful than the almost non-existent DDD examples that are currently available.

Get text from DataGridView selected cells

Private Sub DataGridView1_CellClick(ByVal sender As System.Object, _
                                    ByVal e As DataGridViewCellEventArgs) _
                                    Handles DataGridView1.CellClick
End Sub

Regular expression to extract text between square brackets


Will capture content without brackets

  • (?<=\[) - positive lookbehind for [

  • .*? - non greedy match for the content

  • (?=\]) - positive lookahead for ]

EDIT: for nested brackets the below regex should work:


Get value of c# dynamic property via string

public static object GetProperty(object target, string name)
    var site = System.Runtime.CompilerServices.CallSite<Func<System.Runtime.CompilerServices.CallSite, object, object>>.Create(Microsoft.CSharp.RuntimeBinder.Binder.GetMember(0, name, target.GetType(), new[]{Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo.Create(0,null)}));
    return site.Target(site, target);

Add reference to Microsoft.CSharp. Works also for dynamic types and private properties and fields.

Edit: While this approach works, there is almost 20× faster method from the Microsoft.VisualBasic.dll assembly:

public static object GetProperty(object target, string name)
    return Microsoft.VisualBasic.CompilerServices.Versioned.CallByName(target, name, CallType.Get);

Excel VBA Run-time error '13' Type mismatch

I had the same problem as you mentioned here above and my code was doing great all day yesterday.

I kept on programming this morning and when I opened my application (my file with an Auto_Open sub), I got the Run-time error '13' Type mismatch, I went on the web to find answers, I tried a lot of things, modifications and at one point I remembered that I read somewhere about "Ghost" data that stays in a cell even if we don't see it.

My code do only data transfer from one file I opened previously to another and Sum it. My code stopped at the third SheetTab (So it went right for the 2 previous SheetTab where the same code went without stopping) with the Type mismatch message. And it does that every time at the same SheetTab when I restart my code.

So I selected the cell where it stopped, manually entered 0,00 (Because the Type mismatch comes from a Summation variables declared in a DIM as Double) and copied that cell in all the subsequent cells where the same problem occurred. It solved the problem. Never had the message again. Nothing to do with my code but the "Ghost" or data from the past. It is like when you want to use the Control+End and Excel takes you where you had data once and deleted it. Had to "Save" and close the file when you wanted to use the Control+End to make sure Excel pointed you to the right cell.

offsetTop vs. jQuery.offset().top

This is what jQuery API Doc says about .offset():

Get the current coordinates of the first element, or set the coordinates of every element, in the set of matched elements, relative to the document.

This is what MDN Web API says about .offsetTop:

offsetTop returns the distance of the current element relative to the top of the offsetParent node

This is what jQuery v.1.11 .offset() basically do when getting the coords:

var box = { top: 0, left: 0 };

// BlackBerry 5, iOS 3 (original iPhone)
if ( typeof elem.getBoundingClientRect !== strundefined ) {
  box = elem.getBoundingClientRect();
win = getWindow( doc );
return {
  top:  + ( win.pageYOffset || docElem.scrollTop )  - ( docElem.clientTop  || 0 ),
  left: box.left + ( win.pageXOffset || docElem.scrollLeft ) - ( docElem.clientLeft || 0 )
  • pageYOffset intuitively says how much was the page scrolled
  • docElem.scrollTop is the fallback for IE<9 (which are BTW unsupported in jQuery 2)
  • docElem.clientTop is the width of the top border of an element (the document in this case)
  • elem.getBoundingClientRect() gets the coords relative to the document viewport (see comments). It may return fraction values, so this is the source of your bug. It also may cause a bug in IE<8 when the page is zoomed. To avoid fraction values, try to calculate the position iteratively


  • If you want coords relative to the parent node, use element.offsetTop. Add element.scrollTop if you want to take the parent scrolling into account. (or use jQuery .position() if you are fan of that library)
  • If you want coords relative to the viewport use element.getBoundingClientRect().top. Add window.pageYOffset if you want to take the document scrolling into account. You don't need to subtract document's clientTop if the document has no border (usually it doesn't), so you have position relative to the document
  • Subtract element.clientTop if you don't consider the element border as the part of the element

Using grep and sed to find and replace a string

Standard xargs has no good way to do it; you're better off using find -exec as someone else suggested, or wrap the sed in a script which does nothing if there are no arguments. GNU xargs has the --no-run-if-empty option, and BSD / OS X xargs has the -L option which looks like it should do something similar.

transparent navigation bar ios

I had been working on this, and I was facing a problem using the responses provided here by different users. Problem was a white box behind my NavigationBar transparent image on iOS 13+

enter image description here

My solution is this one

if #available(iOS 13, *) {
    navBar?.standardAppearance.backgroundColor = UIColor.clear
    navBar?.standardAppearance.backgroundEffect = nil
    navBar?.standardAppearance.shadowImage = UIImage()
    navBar?.standardAppearance.shadowColor = .clear
    navBar?.standardAppearance.backgroundImage = UIImage()

Hope this helps anyone with same problem

How to parse data in JSON format?

Following is simple example that may help you:

json_string = """
    "pk": 1, 
    "fa": "", 
    "fb": {
        "fc": "", 
        "fd_id": "12345"

import json
data = json.loads(json_string)
if data["fa"] == "":
    data["fb"]["new_key"] = " was present!"

print json.dumps(data)

The output for the above code will be:

{"pk": 1, "fb": {"new_key": " was present!", "fd_id": "12345", 
 "fc": ""}, "fa": ""}

Note that you can set the ident argument of dump to print it like so (for example,when using print json.dumps(data , indent=4)):

    "pk": 1, 
    "fb": {
        "new_key": " was present!", 
        "fd_id": "12345", 
        "fc": ""
    "fa": ""

Extract / Identify Tables from PDF python

I'd just like to add to the very helpful answer from Kurt Pfeifle - there is now a Python wrapper for Tabula, and this seems to work very well so far:

This will convert your PDF table to a Pandas data frame. You can also set the area in x,y co-ordinates which is obviously very handy for irregular data.

C: socket connection timeout

The two socket options SO_RCVTIMEO and SO_SNDTIMEO have no effect on connect. Below is a link to the screenshot which includes this explanation, here I am just briefing it. The apt way of implementing timeouts with connect are using signal or select or poll.


connect can be interrupted by a self generated signal SIGALRM by using syscall (wrapper) alarm. But, a signal disposition should be installed for the same signal otherwise the program would be terminated. The code goes like this...


static void signal_handler(int signo)
    return; // Do nothing just interrupt.

int main()
    /* Register signal handler */

    struct sigaction act, oact;

    act.sa_handler = signal_handler;
    act.sa_flags = 0;

    act.sa_flags |= SA_INTERRUPT;

    if(sigaction(SIGALRM, &act, &oact) < 0)  // Error registering signal handler.
        fprintf(stderr, "Error registering signal disposition\n");

    /* Prepare your socket and sockaddr structures */

    int sockfd;
    struct sockaddr* servaddr;

    /* Implementing timeout connect */

    int sec = 30;

    if(alarm(sec) != 0)
        fprintf(stderr, "Already timer was set\n");

    if(connect(sockfd, servaddr, sizeof(struct sockaddr)) < 0)
        if(errno == EINTR)
            fprintf(stderr, "Connect timeout\n");
            fprintf(stderr, "Connect failed\n");



    alarm(0);  /* turn off the alarm */

    sigaction(SIGALRM, &oact, NULL);  /* Restore the default actions of SIGALRM */

    /* Use socket */

    /* End program */

    return 0;

Select or Poll

As already some users provided nice explanation on how to use select to achieve connect timeout, it would not be necessary for me to reiterate the same. poll can be used in the same way. However, there are few mistakes that are common in all of the answers, which I would like to address.

  • Even though socket is non-blocking, if the server to which we are connecting is on the same local machine, connect may return with success. So it is advised to check the return value of connect before calling select.

  • Berkeley-derived implementations (and POSIX) have the following rules for non-blocking sockets and connect.

    1) When the connection completes successfully, the descriptor becomes writable (p. 531 of TCPv2).

    2) When the connection establishment encounters an error, the descriptor becomes both readable and writable (p. 530 of TCPv2).

So the code should handle these cases, here I just code the necessary modifications.

/* All the code stays */

/* Modifications at connect */

int conn_ret = connect(sockfd, servaddr, sizeof(struct sockdaddr));

if(conn_ret == 0)
    goto done;

/* Modifications at select */

int sec = 30;
for( ; ; )
    struct timeval timeo;
    timeo.tv_sec = sec;
    timeo.tv_usec = 0;

    fd_set wr_set, rd_set;
    FD_SET(sockfd, &wr_set);
    rd_set = wr_set;
    int sl_ret = select(sockfd + 1, &rd_set, &wr_set, NULL, &timeo);

    /* All the code stays */


    /* Use your socket */

Text from Unix Network Programming Volume 1

What is Cache-Control: private?

RFC 2616, section 14.9.1:

Indicates that all or part of the response message is intended for a single user and MUST NOT be cached by a shared cache...A private (non-shared) cache MAY cache the response.

Browsers could use this information. Of course, the current "user" may mean many things: OS user, a browser user (e.g. Chrome's profiles), etc. It's not specified.

For me, a more concrete example of Cache-Control: private is that proxy servers (which typically have many users) won't cache it. It is meant for the end user, and no one else.

FYI, the RFC makes clear that this does not provide security. It is about showing the correct content, not securing content.

This usage of the word private only controls where the response may be cached, and cannot ensure the privacy of the message content.

Could not calculate build plan: Plugin org.apache.maven.plugins:maven-jar-plugin:2.3.2 or one of its dependencies could not be resolved

I was able to solve the same problem with different solution.

The solution that worked for me was to Right click project "pom.xml" in eclipse and select "Maven Install".

comparing elements of the same array in java

First things first, you need to loop to < a.length rather than a.length - 1. As this is strictly less than you need to include the upper bound.

So, to check all pairs of elements you can do:

for (int i = 0; i < a.length; i++) {
    for (int k = 0; k < a.length; k++) {
        if (a[i] != a[k]) {
            //do stuff

But this will compare, for example a[2] to a[3] and then a[3] to a[2]. Given that you are checking != this seems wasteful.

A better approach would be to compare each element i to the rest of the array:

for (int i = 0; i < a.length; i++) {
    for (int k = i + 1; k < a.length; k++) {
        if (a[i] != a[k]) {
            //do stuff

So if you have the indices [1...5] the comparison would go

  1. 1 -> 2
  2. 1 -> 3
  3. 1 -> 4
  4. 1 -> 5
  5. 2 -> 3
  6. 2 -> 4
  7. 2 -> 5
  8. 3 -> 4
  9. 3 -> 5
  10. 4 -> 5

So you see pairs aren't repeated. Think of a circle of people all needing to shake hands with each other.

How do I append a node to an existing XML file in java

You can parse the existing XML file into DOM and append new elements to the DOM. Very similar to what you did with creating brand new XML. I am assuming you do not have to worry about duplicate server. If you do have to worry about that, you will have to go through the elements in the DOM to check for duplicates.

DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();

/* parse existing file to DOM */
Document document = documentBuilder.parse(new File("exisgint/xml/file"));

Element root = document.getDocumentElement();

for (Server newServer : Collection<Server> bunchOfNewServers){
  Element server = Document.createElement("server");
  /* create and setup the server node...*/


/* use whatever method to output DOM to XML (for example, using transformer like you did).*/

MySQL Error 1264: out of range value for column

The value 3172978990 is greater than 2147483647 – the maximum value for INT – hence the error. MySQL integer types and their ranges are listed here.

Also note that the (10) in INT(10) does not define the "size" of an integer. It specifies the display width of the column. This information is advisory only.

To fix the error, change your datatype to VARCHAR. Phone and Fax numbers should be stored as strings. See this discussion.

Import multiple csv files into pandas and concatenate into one DataFrame

import pandas as pd
import glob

path = r'C:\DRO\DCL_rawdata_files' # use your path
file_path_list = glob.glob(path + "/*.csv")

file_iter = iter(file_path_list)

list_df_csv = []

for file in file_iter:
    lsit_df_csv.append(pd.read_csv(file, header=0))
df = pd.concat(lsit_df_csv, ignore_index=True)

How to save a dictionary to a file?

We can also use the json module in the case when dictionaries or some other data can be easily mapped to JSON format.

import json

# Serialize data into file:
json.dump( data, open( "file_name.json", 'w' ) )

# Read data from file:
data = json.load( open( "file_name.json" ) )

This solution brings many benefits, eg works for Python 2.x and Python 3.x in an unchanged form and in addition, data saved in JSON format can be easily transferred between many different platforms or programs. This data are also human-readable.

Specifying Font and Size in HTML table

Enclose your code with the html and body tags. Size attribute does not correspond to font-size and it looks like its domain does not go beyond value 7. Furthermore font tag is not supported in HTML5. Consider this code for your case

<!DOCTYPE html>

<font size="2" face="Courier New" >
<table width="100%">
<font size="5" face="Courier New" >
<table width="100%">

python dataframe pandas drop column using int

You can simply supply columns parameter to df.drop command so you don't to specify axis in that case, like so

columns_list = [1, 2, 4] # index numbers of columns you want to delete
df = df.drop(columns=df.columns[columns_list])

For reference see columns parameter here:

How to get the browser to navigate to URL in JavaScript

This works in all browsers:

window.location.href = '...';

If you wanted to change the page without it reflecting in the browser back history, you can do:


Create WordPress Page that redirects to another URL

There is a much simpler way in wordpress to create a redirection by using wordpress plugins. So here i found a better way through the plugin Redirection and also you can find other as well on this site Create Url redirect in wordpress through Plugin

Run a command shell in jenkins

Error shows that script does not exists

The file does not exists. check your full path

The system cannot find the file specified

Moreover, to launch .sh scripts into windows, you need to have CYGWIN installed and well configured into your path

Confirm that script exists.

Into jenkins script, do the following to confirm that you do have the file

cd C:\Windows\TEMP\
ls -rtl
sh -xe

"Continue" (to next iteration) on VBScript

A solution I decided on involved the use of a boolean variable to track if the for loop should process its instructions or skip to the next iteration:

Dim continue

For Each item In collection
    continue = True

    If condition1 Then continue = False End If

    If continue Then
        'Do work
    End If

I found the nested loop solutions to be somewhat confusing readability wise. This method also has its own pitfalls since the loop doesn't immediately skip to the next iteration after encountering continue. It would be possible for a later condition to reverse the state of continue. It also has a secondary construct within the initial loop, and requires the declaration of an extra var.

Oh, VBScript...sigh.

Also, if you want to use the accepted answer, which isn't too bad readability wise, you could couple that with the use of : to merge the two loops into what appears to be one:

Dim i

For i = 0 To 10 : Do
    If i = 4 Then Exit Do
    WScript.Echo i
Loop While False : Next

I found it useful to eliminate the extra level of indentation.

How to open a file / browse dialog using javascript?

you can't use directly, but you can call this in other element click event.


<input type="file">
<button>Select file</button>


var botton = document.querySelector('button');
var input = document.querySelector('input');
botton.addEventListener('click', function (e) {;

this tell you Using hidden file input elements using the click() method

Composer: how can I install another dependency without updating old ones?

My use case is simpler, and fits simply your title but not your further detail.

That is, I want to install a new package which is not yet in my composer.json without updating all the other packages.

The solution here is composer require x/y

How do I get the find command to print out the file size with the file name?

You need to use -exec or -printf. Printf works like this:

find . -name *.ear -printf "%p %k KB\n"

-exec is more powerful and lets you execute arbitrary commands - so you could use a version of 'ls' or 'wc' to print out the filename along with other information. 'man find' will show you the available arguments to printf, which can do a lot more than just filesize.

[edit] -printf is not in the official POSIX standard, so check if it is supported on your version. However, most modern systems will use GNU find or a similarly extended version, so there is a good chance it will be implemented.

CMake complains "The CXX compiler identification is unknown"

Run apt-get install build-essential on your system.

This package depends on other packages considered to be essential for builds and will install them. If you find you have to build packages, this can be helpful to avoid piecemeal resolution of dependencies.

See this page for more info.

What does appending "?v=1" to CSS and JavaScript URLs in link and script tags do?

As you can read before, the ?v=1 ensures that your browser gets the version 1 of the file. When you have a new version, you just have to append a different version number and the browser will forget about the old version and loads the new one.

There is a gulp plugin which takes care of version your files during the build phase, so you don't have to do it manually. It's handy and you can easily integrate it in you build process. Here's the link: gulp-annotate

What do numbers using 0x notation mean?

The numbers starting with 0x are hexadecimal (base 16).0x6400 represents 25600.

To convert,

  • multiply the last digit times 1
  • add second-last digit times 16 (16^1)
  • add third-last digit times 256 (16^2)
  • add fourth-last digit times 4096 (16^3)
  • ...and so on

The factors 1, 16, 256, etc. are the increasing powers of 16.

0x6400 = (0*1) + (0*16^1) + (4*16^2) + (6*16^3) = 25600 


0x6400 = (0*1) + (0*16) + (4*256) + (6*4096) = 25600 

bypass invalid SSL certificate in .net core


As mentioned below, not all implementations support this callback (i.e. platforms like iOS). In this case, as the docs say, you can set the validator explicitly:

handler.ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator;

This works too for .NET Core 2.2, 3.0 and 3.1

Old answer, with more control but may throw PlatformNotSupportedException:

You can override SSL cert check on a HTTP call with the a anonymous callback function like this

using (var httpClientHandler = new HttpClientHandler())
   httpClientHandler.ServerCertificateCustomValidationCallback = (message, cert, chain, errors) => { return true; };
   using (var client = new HttpClient(httpClientHandler))
       // Make your request...

Additionally, I suggest to use a factory pattern for HttpClient because it is a shared object that might no be disposed immediately and therefore connections will stay open.

Find the location of a character in string

You can use gregexpr

 gregexpr(pattern ='2',"the2quickbrownfoxeswere2tired")

[1]  4 24
[1] 1 1
[1] TRUE

or perhaps str_locate_all from package stringr which is a wrapper for gregexpr stringi::stri_locate_all (as of stringr version 1.0)

str_locate_all(pattern ='2', "the2quickbrownfoxeswere2tired")

     start end
[1,]     4   4
[2,]    24  24

note that you could simply use stringi

stri_locate_all(pattern = '2', "the2quickbrownfoxeswere2tired", fixed = TRUE)

Another option in base R would be something like

lapply(strsplit(x, ''), function(x) which(x == '2'))

should work (given a character vector x)

How do I get the unix timestamp in C as an int?

An important point is to consider if you perform tasks based on difference between 2 timestamps because you will get odd behavior if you generate it with gettimeofday(), and even clock_gettime(CLOCK_REALTIME,..) at the moment where you will set the time of your system.

To prevent such problem, use clock_gettime(CLOCK_MONOTONIC_RAW, &tms) instead.

How to read/process command line arguments?

I like getopt from stdlib, eg:

    opts, args = getopt.getopt(sys.argv[1:], 'h', ['help'])
except getopt.GetoptError, err: 

for opt, arg in opts:
    if opt in ('-h', '--help'): 

if len(args) != 1:
    usage("specify thing...")

Lately I have been wrapping something similiar to this to make things less verbose (eg; making "-h" implicit).

What is the attribute property="og:title" inside meta tag?

A degree of control is possible over how information travels from a third-party website to Facebook when a page is shared (or liked, etc.). In order to make this possible, information is sent via Open Graph meta tags in the <head> part of the website’s code.

Creating files and directories via Python

import os

path = chap_name

if not os.path.exists(path):

filename = img_alt + '.jpg'
with open(os.path.join(path, filename), 'wb') as temp_file:

Key point is to use os.makedirs in place of os.mkdir. It is recursive, i.e. it generates all intermediate directories. See

Open the file in binary mode as you are storing binary (jpeg) data.

In response to Edit 2, if img_alt sometimes has '/' in it:

img_alt = os.path.basename(img_alt)

SQL LIKE condition to check for integer?

If you want to search as string, you can cast to text like this:

SELECT * FROM books WHERE price::TEXT LIKE '123%'

How to write to a file without overwriting current contents?

Instead of "w" use "a" (append) mode with open function:

with open("games.txt", "a") as text_file:

Connect Android Studio with SVN

Go to File->Settings->Version Control->Subversion enter the path for your SVN executable in the General tab under Subversion configuration directory. Also, you can download a latest SVN client such as VisualSVN and point the path to the executable as mentioned above. That will most likely solve your problem.

Process list on Linux via Python

You can use a third party library, such as PSI:

PSI is a Python package providing real-time access to processes and other miscellaneous system information such as architecture, boottime and filesystems. It has a pythonic API which is consistent accross all supported platforms but also exposes platform-specific details where desirable.

Why does "npm install" rewrite package-lock.json?

Update 3: As other answers point out as well, the npm ci command got introduced in npm 5.7.0 as additional way to achieve fast and reproducible builds in the CI context. See the documentation and npm blog for further information.

Update 2: The issue to update and clarify the documentation is GitHub issue #18103.

Update 1: The behaviour that was described below got fixed in npm 5.4.2: the currently intended behaviour is outlined in GitHub issue #17979.

Original answer: The behaviour of package-lock.json was changed in npm 5.1.0 as discussed in issue #16866. The behaviour that you observe is apparently intended by npm as of version 5.1.0.

That means that package.json can override package-lock.json whenever a newer version is found for a dependency in package.json. If you want to pin your dependencies effectively, you now must specify the versions without a prefix, e.g., you need to write them as 1.2.0 instead of ~1.2.0 or ^1.2.0. Then the combination of package.json and package-lock.json will yield reproducible builds. To be clear: package-lock.json alone no longer locks the root level dependencies!

Whether this design decision was good or not is arguable, there is an ongoing discussion resulting from this confusion on GitHub in issue #17979. (In my eyes it is a questionable decision; at least the name lock doesn't hold true any longer.)

One more side note: there is also a restriction for registries that don’t support immutable packages, such as when you pull packages directly from GitHub instead of See this documentation of package locks for further explanation.

Android:java.lang.OutOfMemoryError: Failed to allocate a 23970828 byte allocation with 2097152 free bytes and 2MB until OOM

Use Glide Library and Override size to less size;

Glide.with(mContext).load(imgID).asBitmap().override(1080, 600).into(mImageView);

Where to find free public Web Services? -- Great collection of all category API's across web. It not only show cases the API's , but also Developers who use those API's in their applications and code samples, rating of the API and much more. They have more than apis they also have sdk and libraries too.

PostgreSQL: Modify OWNER on all tables simultaneously in PostgreSQL

The accepted solution does not take care of function ownership following solution takes care of everything (while reviewing I noticed that it is similar to @magiconair above)

echo "Database: ${DB_NAME}"
echo "Schema: ${SCHEMA}"
echo "User: ${NEW_OWNER}"

pg_dump -s -c -U postgres ${DB_NAME} | egrep "${SCHEMA}\..*OWNER TO"| sed -e "s/OWNER TO.*;$/OWNER TO ${NEW_OWNER};/" | psql -U postgres -d ${DB_NAME}
# do following as last step to allow recovery
psql -U postgres -d postgres -c "ALTER DATABASE ${DB_NAME} OWNER TO ${NEW_OWNER};"

org.glassfish.jersey.servlet.ServletContainer ClassNotFoundException

Below code work for me in web.xml file


How can I decrease the size of Ratingbar?

Working Example

                android:stepSize="0.5" />

and add this in your styles xml file

<style name="RatingBar"   
<item name="colorControlNormal">@color/primary_light</item>
<item name="colorControlActivated">@color/primary_dark</item>

This way you dont need to customise ratingBar.

Disable arrow key scrolling in users browser


Simply prevent the default browser action:

window.addEventListener("keydown", function(e) {
    // space and arrow keys
    if([32, 37, 38, 39, 40].indexOf(e.code) > -1) {
}, false);

If you need to support Internet Explorer or other older browsers, use e.keyCode instead of e.code, but keep in mind that keyCode is deprecated.

Original answer

I used the following function in my own game:

var keys = {};
        keys[e.code] = true;
            case 37: case 39: case 38:  case 40: // Arrow keys
            case 32: e.preventDefault(); break; // Space
            default: break; // do not block other keys
        keys[e.code] = false;

The magic happens in e.preventDefault();. This will block the default action of the event, in this case moving the viewpoint of the browser.

If you don't need the current button states you can simply drop keys and just discard the default action on the arrow keys:

var arrow_keys_handler = function(e) {
        case 37: case 39: case 38:  case 40: // Arrow keys
        case 32: e.preventDefault(); break; // Space
        default: break; // do not block other keys
window.addEventListener("keydown", arrow_keys_handler, false);

Note that this approach also enables you to remove the event handler later if you need to re-enable arrow key scrolling:

window.removeEventListener("keydown", arrow_keys_handler, false);


How do you use math.random to generate random ints?

As an alternative, if there's not a specific reason to use Math.random(), use Random.nextInt():

import java.util.Random;

Random rnd = new Random();
int abc = rnd.nextInt(100); // +1 if you want 1-100, otherwise will be 0-99.

Which HTML Parser is the best?

The best I've seen so far is HtmlCleaner:

HtmlCleaner is open-source HTML parser written in Java. HTML found on Web is usually dirty, ill-formed and unsuitable for further processing. For any serious consumption of such documents, it is necessary to first clean up the mess and bring the order to tags, attributes and ordinary text. For the given HTML document, HtmlCleaner reorders individual elements and produces well-formed XML. By default, it follows similar rules that the most of web browsers use in order to create Document Object Model. However, user may provide custom tag and rule set for tag filtering and balancing.

With HtmlCleaner you can locate any element using XPath.

For other html parsers see this SO question.

Exception in thread "main" java.lang.Error: Unresolved compilation problems

Your problem is in this line: Message messageObject = new Message ();
This error says that the Message class is not known at compile time.

So you need to import the Message class.

Something like this:

import package1.package2.Message;

Check this out.

How can I remove a key and its value from an associative array?

You can use unset:



$array = array("key1" => "value1", "key2" => "value2");




    [key1] => value1
    [key2] => value2
    [key2] => value2

Allow only numbers to be typed in a textbox

With HTML5 you can do

<input type="number">

You can also use a regex pattern to limit the input text.

<input type="text" pattern="^[0-9]*$" />

How to get a variable from a file to another file in Node.js

You need module.exports:


An object which is shared between all instances of the current module and made accessible through require(). exports is the same as the module.exports object. See src/node.js for more information. exports isn't actually a global but rather local to each module.

For example, if you would like to expose variableName with value "variableValue" on sourceFile.js then you can either set the entire exports as such:

module.exports = { variableName: "variableValue" };

Or you can set the individual value with:

module.exports.variableName = "variableValue";

To consume that value in another file, you need to require(...) it first (with relative pathing):

const sourceFile = require('./sourceFile');

Alternatively, you can deconstruct it.

const { variableName } = require('./sourceFile');
//            current directory --^
// ../     would be one directory down
// ../../  is two directories down

If all you want out of the file is variableName then


const variableName = 'variableValue'
module.exports = variableName


const variableName = require('./sourceFile')

Edit (2020):

Since Node.js version 8.9.0, you can also use ECMAScript Modules with varying levels of support. The documentation.

  • For Node v13.9.0 and beyond, experimental modules are enabled by default
  • For versions of Node less than version 13.9.0, use --experimental-modules

Node.js will treat the following as ES modules when passed to node as the initial input, or when referenced by import statements within ES module code:

  • Files ending in .mjs.
  • Files ending in .js when the nearest parent package.json file contains a top-level field "type" with a value of "module".
  • Strings passed in as an argument to --eval or --print, or piped to node via STDIN, with the flag --input-type=module.

Once you have it setup, you can use import and export.

Using the example above, there are two approaches you can take


// This is a named export of variableName
export const variableName = 'variableValue'
// Alternatively, you could have exported it as a default. 
// For sake of explanation, I'm wrapping the variable in an object
// but it is not necessary. 
// You can actually omit declaring what variableName is here. 
// { variableName } is equivalent to { variableName: variableName } in this case. 
export default { variableName: variableName } 


// There are three ways of importing. 
// If you need access to a non-default export, then 
// you use { nameOfExportedVariable } 
import { variableName } from './sourceFile'
console.log(variableName) // 'variableValue'

// Otherwise, you simply provide a local variable name 
// for what was exported as default.
import sourceFile from './sourceFile'
console.log(sourceFile.variableName) // 'variableValue'


// The third way of importing is for situations where there
// isn't a default export but you want to warehouse everything
// under a single variable. Say you have:
export const a = 'A'
export const b = 'B'


// Then you can import all exports under a single variable
// with the usage of * as:
import * as sourceFileWithoutDefault from './sourceFileWithoutDefault'

console.log(sourceFileWithoutDefault.a) // 'A'
console.log(sourceFileWithoutDefault.b) // 'B'

// You can use this approach even if there is a default export:
import * as sourceFile from './sourceFile'

// Default exports are under the variable default:
console.log(sourceFile.default) // { variableName: 'variableValue' }

// As well as named exports:
console.log(sourceFile.variableName) // 'variableValue

How to check if number is divisible by a certain number?

package lecture3;

import java.util.Scanner;

public class divisibleBy2and5 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("Enter an integer number:");
        Scanner input = new Scanner(;
        int x;
        x = input.nextInt();
         if (x % 2==0){
             System.out.println("The integer number you entered is divisible by 2");
             System.out.println("The integer number you entered is not divisible by 2");
             if(x % 5==0){
                 System.out.println("The integer number you entered is divisible by 5");
                 System.out.println("The interger number you entered is not divisible by 5");


Graphviz: How to go from .dot to a graph?

This should combine a lot of answers.

# Convert dot to png via graphviz
dot -Tpng -o filename.png

# Convert dot to svg via graphviz
dot -Tsvg -o filename.svg

# Convert dot to eps via graphviz
dot -Tps -o filename.eps

Keep in mind that on OSX (MAC), you need to install homebrew to install graphviz to be able to use the dot commands above.

brew install graphviz

It is also possible to install Graphviz (and use the commands above) through the package manager functionality of conda if you have Anaconda installed.

conda install python-graphviz

Android Fastboot devices not returning device

For Windows:

  • Open device manager
  • Find Unknown "Android" device (likely listed under Other devices with an exclamation mark)
  • Update driver
  • Browse my computer for driver software
  • Let me pick from a list of devices, select List All Devices
  • Under "Android device" or "Google Inc", you will find "Android Bootloader Interface"
  • Choose "Android Bootloader Interface"
  • Click "yes" when it says that driver might not be compatible

How do I create dynamic variable names inside a loop?

var marker  = [];
for ( var i = 0; i < 6; i++) {               

Switch to another branch without changing the workspace files

Simplest way to do is as follows:

git fetch && git checkout <branch_name>

What does "<>" mean in Oracle

It means 'not equal to'. So you're filtering out records where ordid is 605. Overall you're looking for any records which have the same prodid and qty values as those assigned to ordid 605, but which are for a different order.

Naming convention - underscore in C++ and C# variables

Old question, new answer (C#).

Another use of underscores for C# is with ASP NET Core's DI (dependency injection). Private readonly variables of a class which got assigned to the injected interface during construction should start with an underscore. I guess it's a debate whether to use underscore for every private member of a class (although Microsoft itself follows it) but this one is certain.

private readonly ILogger<MyDependency> _logger;

public MyDependency(ILogger<MyDependency> logger)
    _logger = logger;

How to find specific lines in a table using Selenium?

You want:

int rowNumber=...;
string value = driver.findElement(By.xpath("//div[@id='productOrderContainer']/table/tbody/tr[" + rowNumber +"]/div[id='something']")).getText();

In other words, locate <DIV> with the id "something" contained within the rowNumberth <TR> of the <TABLE> contained within the <DIV> with the id "productOrderContainer", and then get its text value (which is what I believe you mean by "get me the value in <div id='something'>"

Android : change button text and background color

Just complementing @Jonsmoke's answer.

For API level 21 and above you can use :


in XML for the button layout.

For API level below 21 use an AppCompatButton using app namespace instead of android for backgroundTint.

For example:

    android:text="My Button"
    app:backgroundTint="@android:color/white" />

How can you create multiple cursors in Visual Studio Code

In Visual Studio without mouse: Alt+Shift+{ Arrow }.

Difference between Method and Function?

Both are the same, both are a term which means to encapsulate some code into a unit of work which can be called from elsewhere.

Historically, there may have been a subtle difference with a "method" being something which does not return a value, and a "function" one which does. in C# that would translate as:

public void DoSomething() {} // method
public int DoSomethingAndReturnMeANumber(){} // function

But really, I re-iterate that there is really no difference in the 2 concepts.

setState() inside of componentDidUpdate()

The componentDidUpdate signature is void::componentDidUpdate(previousProps, previousState). With this you will be able to test which props/state are dirty and call setState accordingly.


componentDidUpdate(previousProps, previousState) {
    if ( !== {

Should I use "camel case" or underscores in python?

Function names should be lowercase, with words separated by underscores as necessary to improve readability. mixedCase is allowed only in contexts where that's already the prevailing style

Check out its already been answered, click here

Check if null Boolean is true results in exception

If you don't like extra null checks:

if (Boolean.TRUE.equals(value)) {...}

Converting NSString to NSDate (and back again)

NSString to NSDate or NSDate to NSString

//This method is used to get NSDate from string 
//Pass the date formate ex-"dd-MM-yyyy hh:mm a"
+ (NSDate*)getDateFromString:(NSString *)dateString withFormate:(NSString *)formate  {

    // Converted date from date string
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"]];
    [dateFormatter setDateFormat:formate];
    NSDate *convertedDate         = [dateFormatter dateFromString:dateString];
    return convertedDate;

//This method is used to get the NSString for NSDate
//Pass the date formate ex-"dd-MM-yyyy hh:mm a"
+ (NSString *)getDateStringFromDate:(NSDate *)date withFormate:(NSString *)formate {

    // Converted date from date string
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    //[dateFormatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"en_US"]];
    [dateFormatter setDateFormat:formate];
    NSString *convertedDate         = [dateFormatter stringFromDate:date];
    return convertedDate;

Where can I find WcfTestClient.exe (part of Visual Studio)

For 64 bit OS, its here (If .Net 4.5) : C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE

PHP split alternative?

explode is an alternative. However, if you meant to split through a regular expression, the alternative is preg_split instead.

Using Gradle to build a jar with dependencies

For those who need to build more than one jar from the project.

Create a function in gradle:

void jarFactory(Jar jarTask, jarName, mainClass) {
    jarTask.doFirst {
        println 'Build jar ' + + + ' started'

    jarTask.manifest {
                'Main-Class':  mainClass
    jarTask.classifier = 'all'
    jarTask.baseName = jarName
    jarTask.from {
        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
        exclude "META-INF/*.SF"
        exclude "META-INF/*.DSA"
        exclude "META-INF/*.RSA"
    jarTask.with jar 
    jarTask.doFirst {
        println 'Build jar ' + + ' ended'

then call:

task makeMyJar(type: Jar) {
    jarFactory(it, 'MyJar', '')

Works on gradle 5.

Jar will be placed at ./build/libs.

'numpy.ndarray' object is not callable error

The error TypeError: 'numpy.ndarray' object is not callable means that you tried to call a numpy array as a function. We can reproduce the error like so in the repl:

In [16]: import numpy as np

In [17]: np.array([1,2,3])()
TypeError                                 Traceback (most recent call last)
/home/user/<ipython-input-17-1abf8f3c8162> in <module>()
----> 1 np.array([1,2,3])()

TypeError: 'numpy.ndarray' object is not callable

If we are to assume that the error is indeed coming from the snippet of code that you posted (something that you should check,) then you must have reassigned either pd.rolling_mean or pd.rolling_std to a numpy array earlier in your code.

What I mean is something like this:

In [1]: import numpy as np

In [2]: import pandas as pd

In [3]: pd.rolling_mean(np.array([1,2,3]), 20, min_periods=5) # Works
Out[3]: array([ nan,  nan,  nan])

In [4]: pd.rolling_mean = np.array([1,2,3])

In [5]: pd.rolling_mean(np.array([1,2,3]), 20, min_periods=5) # Doesn't work anymore...
TypeError                                 Traceback (most recent call last)
/home/user/<ipython-input-5-f528129299b9> in <module>()
----> 1 pd.rolling_mean(np.array([1,2,3]), 20, min_periods=5) # Doesn't work anymore...

TypeError: 'numpy.ndarray' object is not callable

So, basically you need to search the rest of your codebase for pd.rolling_mean = ... and/or pd.rolling_std = ... to see where you may have overwritten them.

Also, if you'd like, you can put in reload(pd) just before your snippet, which should make it run by restoring the value of pd to what you originally imported it as, but I still highly recommend that you try to find where you may have reassigned the given functions.

How can I query a value in SQL Server XML column

declare @T table(Roles xml)

insert into @T values

declare @Role varchar(10)

set @Role = 'Beta'

select Roles
from @T
where Roles.exist('/root/role/text()[. = sql:variable("@Role")]') = 1

If you want the query to work as where col like '%Beta%' you can use contains

declare @T table(Roles xml)

insert into @T values

declare @Role varchar(10)

set @Role = 'et'

select Roles
from @T
where Roles.exist('/root/role/text()[contains(., sql:variable("@Role"))]') = 1

C#: List All Classes in Assembly

Use Assembly.GetTypes. For example:

Assembly mscorlib = typeof(string).Assembly;
foreach (Type type in mscorlib.GetTypes())

How to get records randomly from the oracle database?

In summary, two ways were introduced

1) using order by DBMS_RANDOM.VALUE clause
2) using sample([%]) function

The first way has advantage in 'CORRECTNESS' which means you will never fail get result if it actually exists, while in the second way you may get no result even though it has cases satisfying the query condition since information is reduced during sampling.

The second way has advantage in 'EFFICIENT' which mean you will get result faster and give light load to your database. I was given an warning from DBA that my query using the first way gives loads to the database

You can choose one of two ways according to your interest!

What does axis in pandas mean?

These answers do help explain this, but it still isn't perfectly intuitive for a non-programmer (i.e. someone like me who is learning Python for the first time in context of data science coursework). I still find using the terms "along" or "for each" wrt to rows and columns to be confusing.

What makes more sense to me is to say it this way:

  • Axis 0 will act on all the ROWS in each COLUMN
  • Axis 1 will act on all the COLUMNS in each ROW

So a mean on axis 0 will be the mean of all the rows in each column, and a mean on axis 1 will be a mean of all the columns in each row.

Ultimately this is saying the same thing as @zhangxaochen and @Michael, but in a way that is easier for me to internalize.

How do I remove blank pages coming between two chapters in Appendix?

One thing I discovered is that using the \include command will often insert and extra blank page. Riffing on the previous trick with the \let command, I inserted \let\include\input near the beginning of the document, and that got rid of most of the excessive blank pages.

How to deal with bad_alloc in C++?

You can catch it like any other exception:

try {
catch (const std::bad_alloc&) {
  return -1;

Quite what you can usefully do from this point is up to you, but it's definitely feasible technically.

In general you cannot, and should not try, to respond to this error. bad_alloc indicates that a resource cannot be allocated because not enough memory is available. In most scenarios your program cannot hope to cope with that, and terminating soon is the only meaningful behaviour.

Worse, modern operating systems often over-allocate: on such systems, malloc and new can return a valid pointer even if there is not enough free memory left – std::bad_alloc will never be thrown, or is at least not a reliable sign of memory exhaustion. Instead, attempts to access the allocated memory will then result in a segmentation fault, which is not catchable (you can handle the segmentation fault signal, but you cannot resume the program afterwards).

The only thing you could do when catching std::bad_alloc is to perhaps log the error, and try to ensure a safe program termination by freeing outstanding resources (but this is done automatically in the normal course of stack unwinding after the error gets thrown if the program uses RAII appropriately).

In certain cases, the program may attempt to free some memory and try again, or use secondary memory (= disk) instead of RAM but these opportunities only exist in very specific scenarios with strict conditions:

  1. The application must ensure that it runs on a system that does not overcommit memory, i.e. it signals failure upon allocation rather than later.
  2. The application must be able to free memory immediately, without any further accidental allocations in the meantime.

It’s exceedingly rare that applications have control over point 1 — userspace applications never do, it’s a system-wide setting that requires root permissions to change.1

OK, so let’s assume you’ve fixed point 1. What you can now do is for instance use a LRU cache for some of your data (probably some particularly large business objects that can be regenerated or reloaded on demand). Next, you need to put the actual logic that may fail into a function that supports retry — in other words, if it gets aborted, you can just relaunch it:

lru_cache<widget> widget_cache;

double perform_operation(int widget_id) {
    std::optional<widget> maybe_widget = widget_cache.find_by_id(widget_id);
    if (not maybe_widget) {
        maybe_widget =, load_widget_from_disk(widget_id));
    return maybe_widget->frobnicate();


for (int num_attempts = 0; num_attempts < MAX_NUM_ATTEMPTS; ++num_attempts) {
    try {
        return perform_operation(widget_id);
    } catch (std::bad_alloc const&) {
        if (widget_cache.empty()) throw; // memory error elsewhere.

// Handle too many failed attempts here.

But even here, using std::set_new_handler instead of handling std::bad_alloc provides the same benefit and would be much simpler.

1 If you’re creating an application that does control point 1, and you’re reading this answer, please shoot me an email, I’m genuinely curious about your circumstances.

What is the C++ Standard specified behavior of new in c++?

The usual notion is that if new operator cannot allocate dynamic memory of the requested size, then it should throw an exception of type std::bad_alloc.
However, something more happens even before a bad_alloc exception is thrown:

C++03 Section says

An allocation function that fails to allocate storage can invoke the currently installed new_handler(, if any. [Note: A program-supplied allocation function can obtain the address of the currently installed new_handler using the set_new_handler function (] If an allocation function declared with an empty exception-specification (15.4), throw(), fails to allocate storage, it shall return a null pointer. Any other allocation function that fails to allocate storage shall only indicate failure by throw-ing an exception of class std::bad_alloc ( or a class derived from std::bad_alloc.

Consider the following code sample:

#include <iostream>
#include <cstdlib>

// function to call if operator new can't allocate enough memory or error arises
void outOfMemHandler()
    std::cerr << "Unable to satisfy request for memory\n";


int main()
    //set the new_handler

    //Request huge memory size, that will cause ::operator new to fail
    int *pBigDataArray = new int[100000000L];

    return 0;

In the above example, operator new (most likely) will be unable to allocate space for 100,000,000 integers, and the function outOfMemHandler() will be called, and the program will abort after issuing an error message.

As seen here the default behavior of new operator when unable to fulfill a memory request, is to call the new-handler function repeatedly until it can find enough memory or there is no more new handlers. In the above example, unless we call std::abort(), outOfMemHandler() would be called repeatedly. Therefore, the handler should either ensure that the next allocation succeeds, or register another handler, or register no handler, or not return (i.e. terminate the program). If there is no new handler and the allocation fails, the operator will throw an exception.

What is the new_handler and set_new_handler?

new_handler is a typedef for a pointer to a function that takes and returns nothing, and set_new_handler is a function that takes and returns a new_handler.

Something like:

typedef void (*new_handler)();
new_handler set_new_handler(new_handler p) throw();

set_new_handler's parameter is a pointer to the function operator new should call if it can't allocate the requested memory. Its return value is a pointer to the previously registered handler function, or null if there was no previous handler.

How to handle out of memory conditions in C++?

Given the behavior of newa well designed user program should handle out of memory conditions by providing a proper new_handlerwhich does one of the following:

Make more memory available: This may allow the next memory allocation attempt inside operator new's loop to succeed. One way to implement this is to allocate a large block of memory at program start-up, then release it for use in the program the first time the new-handler is invoked.

Install a different new-handler: If the current new-handler can't make any more memory available, and of there is another new-handler that can, then the current new-handler can install the other new-handler in its place (by calling set_new_handler). The next time operator new calls the new-handler function, it will get the one most recently installed.

(A variation on this theme is for a new-handler to modify its own behavior, so the next time it's invoked, it does something different. One way to achieve this is to have the new-handler modify static, namespace-specific, or global data that affects the new-handler's behavior.)

Uninstall the new-handler: This is done by passing a null pointer to set_new_handler. With no new-handler installed, operator new will throw an exception ((convertible to) std::bad_alloc) when memory allocation is unsuccessful.

Throw an exception convertible to std::bad_alloc. Such exceptions are not be caught by operator new, but will propagate to the site originating the request for memory.

Not return: By calling abort or exit.

Show a popup/message box from a Windows batch file

You can use Zenity. Zenity allows for the execution of dialog boxes in command-line and shell scripts. More info can also be found on Wikipedia.

It is cross-platform: a Windows installer for Windows can be found here.

what is .subscribe in angular?

In Angular (currently on Angular-6) .subscribe() is a method on the Observable type. The Observable type is a utility that asynchronously or synchronously streams data to a variety of components or services that have subscribed to the observable.

The observable is an implementation/abstraction over the promise chain and will be a part of ES7 as a proposed and very supported feature. In Angular it is used internally due to rxjs being a development dependency.

An observable itself can be thought of as a stream of data coming from a source, in Angular this source is an API-endpoint, a service, a database or another observable. But the power it has is that it's not expecting a single response. It can have one or many values that are returned.

Link to rxjs for observable/subscribe docs here:

Subscribe takes 3 methods as parameters each are functions:

  • next: For each item being emitted by the observable perform this function
  • error: If somewhere in the stream an error is found, do this method
  • complete: Once all items are complete from the stream, do this method

Within each of these, there is the potentional to pipe (or chain) other utilities called operators onto the results to change the form or perform some layered logic.

In the simple example above:

.subscribe(hero => this.hero = hero); basically says on this observable take the hero being emitted and set it to this.hero.

Adding this answer to give more context to Observables based off the documentation and my understanding.

How can I execute Shell script in Jenkinsfile?

If you see your error message it says

Building in workspace /var/lib/jenkins/workspace/AutoScript

and as per your comments you have put in


Hence Jenkins is not able to find the file. In your build step do this thing, it will work

cd             # which will point to /var/lib/jenkins
./   # it will run your script

If it still fails try to chown the file as jenkin user may not have file permission, but I think if you do above step you will be able to run.

Increasing heap space in Eclipse: (java.lang.OutOfMemoryError)

In eclipse.ini file, make below entries




Is there an ignore command for git like there is for svn?

It's useful to define a complete .gitignore file for your project. The reward is safe use of the convenient --all or -a flag to commands like add and commit.

Also, consider defining a global ~/.gitignore file for commonly ignored patterns such as *~, which covers temporary files created by Emacs.

Callback when DOM is loaded in react.js

Add onload listener in componentDidMount

class Comp1 extends React.Component {
 constructor(props) {
    this.handleLoad = this.handleLoad.bind(this);

 componentDidMount() {
    window.addEventListener('load', this.handleLoad);

 componentWillUnmount() { 
   window.removeEventListener('load', this.handleLoad)  

 handleLoad() {
  $("myclass") //  $ is available here

What is the canonical way to trim a string in Ruby without creating a new string?

If you want to use another method after you need something like this:

( str.strip || str ).split(',')

This way you can strip and still do something after :)

Java; String replace (using regular expressions)?

Try this, may not be the best way. but it works

String str = "5 * x^3 - 6 * x^1 + 1";
str = str.replaceAll("(?x)(\\d+)(\\s+?\\*?\\s+?)(\\w+?)(\\^+?)(\\d+?)", "$1$3<sup>$5</sup>");

Excel formula to search if all cells in a range read "True", if not, then show "False"

As it appears you have the values as text, and not the numeric True/False, then you can use either COUNTIF or SUMPRODUCT


Why are my CSS3 media queries not working on mobile devices?

I suspect the keyword only may be the issue here. I have no issues using media queries like this:

@media screen and (max-width: 480px) { }

How to resize superview to fit all subviews with autolayout?

Eric Baker's comment tipped me off to the core idea that in order for a view to have its size be determined by the content placed within it, then the content placed within it must have an explicit relationship with the containing view in order to drive its height (or width) dynamically. "Add subview" does not create this relationship as you might assume. You have to choose which subview is going to drive the height and/or width of the container... most commonly whatever UI element you have placed in the lower right hand corner of your overall UI. Here's some code and inline comments to illustrate the point.

Note, this may be of particular value to those working with scroll views since it's common to design around a single content view that determines its size (and communicates this to the scroll view) dynamically based on whatever you put in it. Good luck, hope this helps somebody out there.

//  ViewController.m
//  AutoLayoutDynamicVerticalContainerHeight

#import "ViewController.h"

@interface ViewController ()
@property (strong, nonatomic) UIView *contentView;
@property (strong, nonatomic) UILabel *myLabel;
@property (strong, nonatomic) UILabel *myOtherLabel;

@implementation ViewController

- (void)viewDidLoad
    [super viewDidLoad];

    self.contentView = [[UIView alloc] init];
    self.myLabel = [[UILabel alloc] init];
    self.myOtherLabel = [[UILabel alloc] init];
    NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(_contentView, _myLabel, _myOtherLabel);

    self.contentView.translatesAutoresizingMaskIntoConstraints = NO;
    self.myLabel.translatesAutoresizingMaskIntoConstraints = NO;
    self.myOtherLabel.translatesAutoresizingMaskIntoConstraints = NO;

    [self.view addSubview:self.contentView]; // View adds content view
    [self.contentView addSubview:self.myLabel]; // Content view adds my label (and all other UI... what's added here drives the container height (and width))
    [self.contentView addSubview:self.myOtherLabel];

    // LAYOUT

    // Layout CONTENT VIEW (Pinned to left, top. Note, it expects to get its vertical height (and horizontal width) dynamically based on whatever is placed within).
    // Note, if you don't want horizontal width to be driven by content, just pin left AND right to superview.
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_contentView]" options:0 metrics:0 views:viewsDictionary]]; // Only pinned to left, no horizontal width yet
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_contentView]" options:0 metrics:0 views:viewsDictionary]]; // Only pinned to top, no vertical height yet

    // ^To me this is what's weird... but okay once you understand...

    // Layout MY LABEL (Anchor to upper left with default margin, width and height are dynamic based on text, font, etc (i.e. UILabel has an intrinsicContentSize))
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_myLabel]" options:0 metrics:0 views:viewsDictionary]];
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[_myLabel]" options:0 metrics:0 views:viewsDictionary]];

    // Layout MY OTHER LABEL (Anchored by vertical space to the sibling label that comes before it)
    // Note, this is the view that we are choosing to use to drive the height (and width) of our container...

    // The LAST "|" character is KEY, it's what drives the WIDTH of contentView (red color)
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[_myOtherLabel]-|" options:0 metrics:0 views:viewsDictionary]];

    // Again, the LAST "|" character is KEY, it's what drives the HEIGHT of contentView (red color)
    [self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[_myLabel]-[_myOtherLabel]-|" options:0 metrics:0 views:viewsDictionary]];

    self.view.backgroundColor = [UIColor purpleColor];
    self.contentView.backgroundColor = [UIColor redColor];
    self.myLabel.backgroundColor = [UIColor orangeColor];
    self.myOtherLabel.backgroundColor = [UIColor greenColor];


    // Configure MY LABEL
    self.myLabel.text = @"HELLO WORLD\nLine 2\nLine 3, yo";
    self.myLabel.numberOfLines = 0; // Let it flow

    // Configure MY OTHER LABEL
    self.myOtherLabel.text = @"My OTHER label... This\nis the UI element I'm\narbitrarily choosing\nto drive the width and height\nof the container (the red view)";
    self.myOtherLabel.numberOfLines = 0;
    self.myOtherLabel.font = [UIFont systemFontOfSize:21];


How to resize superview to fit all subviews with autolayout.png

Async await in linq select

I wanted to call Select(...) but ensure it ran in sequence because running in parallel would cause some other concurrency problems, so I ended up with this. I cannot call .Result because it will block the UI thread.

public static class TaskExtensions
    public static async Task<IEnumerable<TResult>> SelectInSequenceAsync<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, Task<TResult>> asyncSelector)
        var result = new List<TResult>();
        foreach (var s in source)
            result.Add(await asyncSelector(s));
        return result;


var inputs = events.SelectInSequenceAsync(ev => ProcessEventAsync(ev))
                   .Where(i => i != null)

I am aware that Task.WhenAll is the way to go when we can run in parallel.

Serializing PHP object to JSON

Following code is doing the job using reflection. It assumes you have getters for the properties you want to serialize


     * Serialize a simple PHP object into json
     * Should be used for POPO that has getter methods for the relevant properties to serialize
     * A property can be simple or by itself another POPO object
     * Class CleanJsonSerializer
    class CleanJsonSerializer {

     * Local cache of a property getters per class - optimize reflection code if the same object appears several times
     * @var array
    private $classPropertyGetters = array();

     * @param mixed $object
     * @return string|false
    public function serialize($object)
        return json_encode($this->serializeInternal($object));

     * @param $object
     * @return array
    private function serializeInternal($object)
        if (is_array($object)) {
            $result = $this->serializeArray($object);
        } elseif (is_object($object)) {
            $result = $this->serializeObject($object);
        } else {
            $result = $object;
        return $result;

     * @param $object
     * @return \ReflectionClass
    private function getClassPropertyGetters($object)
        $className = get_class($object);
        if (!isset($this->classPropertyGetters[$className])) {
            $reflector = new \ReflectionClass($className);
            $properties = $reflector->getProperties();
            $getters = array();
            foreach ($properties as $property)
                $name = $property->getName();
                $getter = "get" . ucfirst($name);
                try {
                    $getters[$name] = $getter;
                } catch (\Exception $e) {
                    // if no getter for a specific property - ignore it
            $this->classPropertyGetters[$className] = $getters;
        return $this->classPropertyGetters[$className];

     * @param $object
     * @return array
    private function serializeObject($object) {
        $properties = $this->getClassPropertyGetters($object);
        $data = array();
        foreach ($properties as $name => $property)
            $data[$name] = $this->serializeInternal($object->$property());
        return $data;

     * @param $array
     * @return array
    private function serializeArray($array)
        $result = array();
        foreach ($array as $key => $value) {
            $result[$key] = $this->serializeInternal($value);
        return $result;

Break promise chain and call a function based on the step in the chain where it is broken (rejected)

If you want to solve this issue using async/await:

(async function(){    
    try {        
        const response1, response2, response3
        response1 = await promise1()

            response2 = await promise2()
            response3 = await promise3()
        return [response1, response2, response3]
    } catch (error) {
        return []


Adjust plot title (main) position

We can use title() function with negative line value to bring down the title.

See this example:

plot(1, 1)
title("Title", line = -2)

enter image description here

Execute a large SQL script (with GO commands)

If you don't want to go the SMO route you can search and replace "GO" for ";" and the query as you would. Note that soly the the last result set will be returned.

Selenium WebDriver: Wait for complex page with JavaScript to load

You can write some logic to handle this. I have write a method that will return the WebElement and this method will be called three times or you can increase the time and add a null check for WebElement Here is an example

public static void main(String[] args) {
        WebDriver driver = new FirefoxDriver();
        WebElement webElement = getWebElement(driver, "homekkkkkkkkkkkk");
        int i = 1;
        while (webElement == null && i < 4) {
            webElement = getWebElement(driver, "homessssssssssss");

    public static WebElement getWebElement(WebDriver driver, String id) {
        WebElement myDynamicElement = null;
        try {
            myDynamicElement = (new WebDriverWait(driver, 10))
            return myDynamicElement;
        } catch (TimeoutException ex) {
            return null;

What is the best way to get the minimum or maximum value from an Array of numbers?

If you are building the array once and want to find the maximum just once, iterating is the best you can do.

When you want to modify the array and occasionally want to know the maximum element, you should use a Priority Queue. One of the best data structures for that is a Fibonacci Heap, if this is too complicated use a Binary Heap which is slower but still good.

To find minimum and maximum, just build two heaps and change the sign of the numbers in one of them.

'npm' is not recognized as internal or external command, operable program or batch file

Well in my case doing testing via Mocha i tried everything just to realize i have to remove single quotes around my test case script tag inside package.json.

I am running mocha test case on all *.test.js files as can see below:



 "scripts": {
    "test": "mocha server/**/*.test.js",
    "test-watch": "nodemon --exec 'npm run test'"

After(removing single quotes - npm run test):

 "scripts": {
    "test": "mocha server/**/*.test.js",
    "test-watch": "nodemon --exec npm run test"

Worked for me, just in case someone else also gets stuck on this.

sqlalchemy: how to join several tables by one query?

A good style would be to setup some relations and a primary key for permissions (actually, usually it is good style to setup integer primary keys for everything, but whatever):

class User(Base):
    __tablename__ = 'users'
    email = Column(String, primary_key=True)
    name = Column(String)

class Document(Base):
    __tablename__ = "documents"
    name = Column(String, primary_key=True)
    author_email = Column(String, ForeignKey(""))
    author = relation(User, backref='documents')

class DocumentsPermissions(Base):
    __tablename__ = "documents_permissions"
    id = Column(Integer, primary_key=True)
    readAllowed = Column(Boolean)
    writeAllowed = Column(Boolean)
    document_name = Column(String, ForeignKey(""))
    document = relation(Document, backref = 'permissions')

Then do a simple query with joins:

query = session.query(User, Document, DocumentsPermissions).join(Document).join(DocumentsPermissions)

How to create a Rectangle object in Java using g.fillRect method

You may try like this:

import java.applet.Applet;
import java.awt.*;

public class Rect1 extends Applet {

  public void paint (Graphics g) {
    g.drawRect (x, y, width, height);    //can use either of the two//
    g.fillRect (x, y, width, height);


where x is x co-ordinate y is y cordinate color=the color you want to use eg

if you want to use rectangle object you could do it like this:

import java.applet.Applet;
import java.awt.*;

public class Rect1 extends Applet {

  public void paint (Graphics g) {    
    Rectangle r = new Rectangle(arg,arg1,arg2,arg3);
    g.fillRect(r.getX(), r.getY(), r.getWidth(), r.getHeight());

PHP executable not found. Install PHP 7 and add it to your PATH or set the php.executablePath setting

This one also works

  1. Remove the "php.executablePath" line from the VS code settings.

  2. Then add the xampp php path to the System variables

enter image description here

enter image description here

After that restart the Visual Studio Code

Find size of an array in Perl

This gets the size by forcing the array into a scalar context, in which it is evaluated as its size:

print scalar @arr;

This is another way of forcing the array into a scalar context, since it's being assigned to a scalar variable:

my $arrSize = @arr;

This gets the index of the last element in the array, so it's actually the size minus 1 (assuming indexes start at 0, which is adjustable in Perl although doing so is usually a bad idea):

print $#arr;

This last one isn't really good to use for getting the array size. It would be useful if you just want to get the last element of the array:

my $lastElement = $arr[$#arr];

Also, as you can see here on Stack Overflow, this construct isn't handled correctly by most syntax highlighters...

Angular checkbox and ng-click

The order of execution of ng-click and ng-model is different with angular 1.2 vs 1.6

You must test, with 1.2 and 1.6,

for example, with angular 1.2, ng-click get execute before ng-model, with angular 1.6, ng-model maybe get excute before ng-click.

so you get 'true checked' / 'false uncheck' value maybe not you expect

Get Table and Index storage size in sql server

This query here will list the total size that a table takes up - clustered index, heap and all nonclustered indices:

    s.Name AS SchemaName,
    t.NAME AS TableName,
    p.rows AS RowCounts,
    SUM(a.total_pages) * 8 AS TotalSpaceKB, 
    SUM(a.used_pages) * 8 AS UsedSpaceKB, 
    (SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB
    sys.tables t
    sys.schemas s ON s.schema_id = t.schema_id
    sys.indexes i ON t.OBJECT_ID = i.object_id
    sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
    sys.allocation_units a ON p.partition_id = a.container_id
    t.NAME NOT LIKE 'dt%'    -- filter out system tables for diagramming
    AND t.is_ms_shipped = 0
    AND i.OBJECT_ID > 255 
    t.Name, s.Name, p.Rows
    s.Name, t.Name

If you want to separate table space from index space, you need to use AND i.index_id IN (0,1) for the table space (index_id = 0 is the heap space, index_id = 1 is the size of the clustered index = data pages) and AND i.index_id > 1 for the index-only space

Validating Phone Numbers Using Javascript

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" type="text/css" href="../Homepage-30-06-2016/Css.css" >

<script type="text/javascript">

        function isChar(evt) {
            evt = (evt) ? evt : window.event;
            var charCode = (evt.which) ? evt.which : evt.keyCode;
            if (charCode > 47 && charCode < 58) {

                document.getElementById("error").innerHTML = "*Please Enter Your Name Only";
                document.getElementById("fullname").style.borderColor = 'red';
                return false;
            else {
                document.getElementById("error").innerHTML = "";
                document.getElementById("fullname").style.borderColor = '';

                return true;


        <h1 style="margin-left:20px;"Registration Form>Registration Form</h1><hr/>

           Name: <input id="fullname" type="text" placeholder="Full Name*"
                 name="fullname" onKeyPress="return isChar(event)" onChange="return isChar(event);"/><label id="error"></label><br /><br />

<button type="submit" id="submit" name="submit" onClick="return valid(event)" class="btn btn-link text-uppercase"> Submit now</button>

In MySQL, how to copy the content of one table to another table within the same database?

If table1 is large and you don't want to lock it for the duration of the copy process, you can do a dump-and-load instead:

CREATE TABLE table2 LIKE table1;

SELECT * INTO OUTFILE '/tmp/table1.txt' FROM table1;
LOAD DATA INFILE '/tmp/table1.txt' INTO TABLE table2;

Way to insert text having ' (apostrophe) into a SQL table

INSERT INTO exampleTbl VALUES('he doesn''t work for me')

If you're adding a record through ASP.NET, you can use the SqlParameter object to pass in values so you don't have to worry about the apostrophe's that users enter in.

How to send a compressed archive that contains executables so that Google's attachment filter won't reject it

tar -cvzf filename.tar.gz directory_to_compress/

Most tar commands have a z option to create a gziped version.

Though seems to me the question is how to circumvent Google. I'm not sure if renaming your output file would fool Google, but you could try. I.e.,

tar -cvzf filename.bla directory_to_compress/

and then send the filename.bla - contents will would be a zipped tar, so at the other end it could be retrieved as usual.

What's the best way to store co-ordinates (longitude/latitude, from Google Maps) in SQL Server?

The way I do it: I store the latitude and longitude and then I have a third column which is a automatic derived geography type of the 1st two columns. The table looks like this:

CREATE TABLE [dbo].[Geopoint]
    [Latitude] float NOT NULL, 
    [Longitude] float NOT NULL, 
    [GeographyPoint]  AS ([geography]::STGeomFromText(((('POINT('+CONVERT([varchar](20),[Longitude]))+' ')+CONVERT([varchar](20),[Latitude]))+')',(4326))) 

This gives you the flexibility of spatial queries on the geoPoint column and you can also retrieve the latitude and longitude values as you need them for display or extracting for csv purposes.

Creating a BAT file for python script


You can use this for some other file types.

How can I style an Android Switch?

You can define the drawables that are used for the background, and the switcher part like this:

    android:track="@drawable/switch_bg" />

Now you need to create a selector that defines the different states for the switcher drawable. Here the copies from the Android sources:

<selector xmlns:android="">
    <item android:state_enabled="false" android:drawable="@drawable/switch_thumb_disabled_holo_light" />
    <item android:state_pressed="true"  android:drawable="@drawable/switch_thumb_pressed_holo_light" />
    <item android:state_checked="true"  android:drawable="@drawable/switch_thumb_activated_holo_light" />
    <item                               android:drawable="@drawable/switch_thumb_holo_light" />

This defines the thumb drawable, the image that is moved over the background. There are four ninepatch images used for the slider:

The deactivated version (xhdpi version that Android is using)The deactivated version
The pressed slider: The pressed slider
The activated slider (on state):The activated slider
The default version (off state): enter image description here

There are also three different states for the background that are defined in the following selector:

<selector xmlns:android="">
    <item android:state_enabled="false" android:drawable="@drawable/switch_bg_disabled_holo_dark" />
    <item android:state_focused="true"  android:drawable="@drawable/switch_bg_focused_holo_dark" />
    <item                               android:drawable="@drawable/switch_bg_holo_dark" />

The deactivated version: The deactivated version
The focused version: The focused version
And the default version:the default version

To have a styled switch just create this two selectors, set them to your Switch View and then change the seven images to your desired style.

Changing route doesn't scroll to top in the new page

This Worked for me including autoscroll

<div class="ngView" autoscroll="true" >

phpmyadmin.pma_table_uiprefs doesn't exist

A really simple solution is to edit /etc/phpmyadmin/ and put

$cfg['Servers'][$i]['table_uiprefs'] = '';

It just manages the UI and who needs the UI if its interfering with display of actual data.


Add space between two particular <td>s

you have to set cellpadding and cellspacing that's it.

<table cellpadding="5" cellspacing="5">

Opposite of append in jquery

The opposite of .append() is .prepend().

From the jQuery documentation for prepend…

The .prepend() method inserts the specified content as the first child of each element in the jQuery collection (To insert it as the last child, use .append()).

I realize this doesn’t answer the OP’s specific case. But it does answer the question heading. :) And it’s the first hit on Google for “jquery opposite append”.

Nginx - Customizing 404 page

Be careful with the syntax! Great Turtle used them interchangeably, but:

error_page 404 = /404.html;

Will return the 404.html page with a status code of 200 (because = has relayed that to this page)

error_page 404 /404.html;

Will return the 404.html page with a (the original) 404 error code.

"Android library projects cannot be launched"?

It says “Android library projects cannot be launched” because Android library projects cannot be launched. That simple. You cannot run a library. If you want to test a library, create an Android project that uses the library, and execute it.

Matplotlib color according to class labels

A simple solution is to assign color for each class. This way, we can control how each color is for each class. For example:

arr1 = [1, 2, 3, 4, 5]
arr2 = [2, 3, 3, 4, 4]
labl = [0, 1, 1, 0, 0]
color= ['red' if l == 0 else 'green' for l in labl]
plt.scatter(arr1, arr2, color=color)

Centering in CSS Grid

I know this question is a couple years old, but I am surprised to find that no one suggested:

   text-align: center;

this is a more universal property than justify-content, and is definitely not unique to grid, but I find that when dealing with text, which is what this question specifically asks about, that it aligns text to the center with-out affecting the space between grid items, or the vertical centering. It centers text horizontally where its stands on its vertical axis. I also find it to remove a layer of complexity that justify-content and align-items adds. justify-content and align-items affects the entire grid item or items, text-align centers the text without affecting the container it is in. Hope this helps.

Raise warning in Python without interrupting program

import warnings

See the python documentation: here

Creating columns in listView and add items

            listView1.View = View.Details;
        listView1.Columns.Add("Target No.", 83, HorizontalAlignment.Center);
        listView1.Columns.Add("   Range   ", 100, HorizontalAlignment.Center);
        listView1.Columns.Add(" Azimuth ", 100, HorizontalAlignment.Center);     

i also had same problem .. i drag column to left .. but now ok .. so let's say i have 283*196 size of listview ..... We declared in the column width -2 for auto width .. For fitting in the listview ,we can divide listview width into 3 parts (83,100,100) ...

How to use "like" and "not like" in SQL MSAccess for the same field?

Try this:

filed like "*AA*" and filed not like "*BB*"

Responsive web design is working on desktop but not on mobile device

I have also faced this problem. Finally I got a solution. Use this bellow code. Hope: problem will be solve.

<meta name="viewport" content="initial-scale=1, maximum-scale=1">

Cannot find java. Please use the --jdkhome switch

  1. Go to the netbeans installation directory
  2. Find configuration file [installation-directory]/etc/netbeans.conf
  3. towards the end find the line netbeans_jdkhome=...
  4. comment this line line using '#'
  5. now run netbeans. launcher will find jdk itself (from $JDK_HOME/$JAVA_HOME) environment variable


sudo vim /usr/local/netbeans-8.2/etc/netbeans.conf

Change Circle color of radio button

I had this problem. If your app has a black background and you have a lot of RadioButtons that are invisible due to the background, it is complicated to edit the android: buttonTint of each one, the best solution is to change the parent theme in your styles.xml file

I changed

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">


<style name="AppTheme" parent="Theme.AppCompat.NoActionBar">

So the RadioButtons' circles became a lighter shade of gray and now they are visible even with a black background.

This is my style.xml file:


<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>

Today's Date in Perl in MM/DD/YYYY format

Formating numbers with leading zero is done easily with "sprintf", a built-in function in perl (documentation with: perldoc perlfunc)

use strict;
use warnings;
use Date::Calc qw();
my ($y, $m, $d) = Date::Calc::Today();
my $ddmmyyyy = sprintf '%02d.%02d.%d', $d, $m, $y;
print $ddmmyyyy . "\n";

This gives you:

14.05.2014 and pass parameters by post method

I created a function to generate a form, based on url, target and an object as the POST/GET data and submit method. It supports nested and mixed types within that object, so it can fully replicate any structure you feed it: PHP automatically parses it and returns it as a nested array. However, there is a single restriction: the brackets [ and ] must not be part of any key in the object (like {"this [key] is problematic" : "hello world"}). If someone knows how to escape it properly, please do tell!

Without further ado, here is the source:

function getForm(url, target, values, method) {_x000D_
  function grabValues(x) {_x000D_
    var path = [];_x000D_
    var depth = 0;_x000D_
    var results = [];_x000D_
    function iterate(x) {_x000D_
      switch (typeof x) {_x000D_
        case 'function':_x000D_
        case 'undefined':_x000D_
        case 'null':_x000D_
        case 'object':_x000D_
          if (Array.isArray(x))_x000D_
            for (var i = 0; i < x.length; i++) {_x000D_
              path[depth++] = i;_x000D_
            for (var i in x) {_x000D_
              path[depth++] = i;_x000D_
            path: path.slice(0),_x000D_
            value: x_x000D_
    return results;_x000D_
  var form = document.createElement("form");_x000D_
  form.method = method;_x000D_
  form.action = url;_x000D_ = target;_x000D_
  var values = grabValues(values);_x000D_
  for (var j = 0; j < values.length; j++) {_x000D_
    var input = document.createElement("input");_x000D_
    input.type = "hidden";_x000D_
    input.value = values[j].value;_x000D_ = values[j].path[0];_x000D_
    for (var k = 1; k < values[j].path.length; k++) {_x000D_ += "[" + values[j].path[k] + "]";_x000D_
  return form;_x000D_

Usage example:

document.body.onclick = function() {_x000D_
  var obj = {_x000D_
    "a": [1, 2, [3, 4]],_x000D_
    "b": "a",_x000D_
    "c": {_x000D_
      "x": [1],_x000D_
      "y": [2, 3],_x000D_
      "z": [{_x000D_
        "a": "Hello",_x000D_
        "b": "World"_x000D_
      }, {_x000D_
        "a": "Hallo",_x000D_
        "b": "Welt"_x000D_
  var form = getForm("", "_blank", obj, "post");_x000D_

Resource from src/main/resources not found after building with maven

Once after we build the jar will have the resource files under BOOT-INF/classes or target/classes folder, which is in classpath, use the below method and pass the file under the src/main/resources as method call getAbsolutePath("certs/uat_staging_private.ppk"), even we can place this method in Utility class and the calling Thread instance will be taken to load the ClassLoader to get the resource from class path.

 public String getAbsolutePath(String fileName) throws IOException {
      return Thread.currentThread().getContextClassLoader().getResource(fileName).getFile();

enter image description here enter image description here

we can add the below tag to tag in pom.xml to include these resource files to build target/classes folder


convert ArrayList<MyCustomClass> to JSONArray

I know its already answered, but theres a better solution here use this code :

for ( Field f : context.getFields() ) {
     if ( f.getType() == String.class ) || ( f.getType() == String.class ) ) {
           //DO String To JSON
     /// And so on...

This way you can access variables from class without manually typing them..

Faster and better .. Hope this helps.

Cheers. :D

D3 transform scale and translate

I realize this question is fairly old, but wanted to share a quick demo of group transforms, paths/shapes, and relative positioning, for anyone else who found their way here looking for more info:

How to get table cells evenly spaced?

If you want all your columns a fixed size, you could use CSS:

    width: 100px;

Or better, use th.TableHeader (I didn't notice that the first time around).

How do I properly escape quotes inside HTML attributes?

Another option is replacing double quotes with single quotes if you don't mind whatever it is. But I don't mention this one:

<option value='"asd'>test</option>

I mention this one:

<option value="'asd">test</option>

In my case I used this solution.