Programs & Examples On #Network storage

bypass invalid SSL certificate in .net core

I solve with this:


public void ConfigureServices(IServiceCollection services)
        services.AddHttpClient("HttpClientWithSSLUntrusted").ConfigurePrimaryHttpMessageHandler(() => new HttpClientHandler
            ClientCertificateOptions = ClientCertificateOption.Manual,
            ServerCertificateCustomValidationCallback =
            (httpRequestMessage, cert, cetChain, policyErrors) =>
                return true;


public UserService(IHttpClientFactory clientFactory, IOptions<AppSettings> appSettings)
        _appSettings = appSettings.Value;
        _clientFactory = clientFactory;

var request = new HttpRequestMessage(...

var client = _clientFactory.CreateClient("HttpClientWithSSLUntrusted");

HttpResponseMessage response = await client.SendAsync(request);

Alternative for frames in html5 using iframes

While I agree with everyone else, if you are dead set on using frames anyway, you can just do index.html in XHTML and then do the contents of the frames in HTML5.

@import vs #import - iOS 7

It currently only works for the built in system frameworks. If you use #import like apple still do importing the UIKit framework in the app delegate it is replaced (if modules is on and its recognised as a system framework) and the compiler will remap it to be a module import and not an import of the header files anyway. So leaving the #import will be just the same as its converted to a module import where possible anyway

Printing the last column of a line in a file

You don't see anything, because of buffering. The output is shown, when there are enough lines or end of file is reached. tail -f means wait for more input, but there are no more lines in file and so the pipe to grep is never closed.

If you omit -f from tail the output is shown immediately:

tail file | grep A1 | awk '{print $NF}'

@EdMorton is right of course. Awk can search for A1 as well, which shortens the command line to

tail file | awk '/A1/ {print $NF}'

or without tail, showing the last column of all lines containing A1

awk '/A1/ {print $NF}' file

Thanks to @MitchellTracy's comment, tail might miss the record containing A1 and thus you get no output at all. This may be solved by switching tail and awk, searching first through the file and only then show the last line:

awk '/A1/ {print $NF}' file | tail -n1

Showing the same file in both columns of a Sublime Text window

I regularly work on the same file in 2 different positions. I solved this in Sublime Text 3 using origami and chain with some additional config.

My workflow is Ctrl + k + 2 splits the view of the file in two (horizontal) panes with the lower one active. Use Ctrl + k + o to toggle between the panes. When done ensure the lower pane is the active and press Ctrl + F4 to close the duplicated view and the pane.

In sublime global settings (not origami settings!) add

"origami_auto_close_empty_panes": true,

Add the following shortcuts

  { "keys": ["ctrl+k", "2"], 
    "command": "chain", 
    "args": {
      "commands": [
        ["create_pane", {"direction": "down"}],
        ["clone_file_to_pane", {"direction": "down"}],

  { "keys": ["ctrl+k", "o"], "command": "focus_neighboring_group" },

Django development IDE

I use Vim:


Sublime Text 2 is pretty awesome. It supports a lot of Vim commands if you want them: Vintage Mode

It has a nice package manager:

I use these packages so far:





Theme - Soda


I still love Vim but ... did I mention that Sublime Text plugins are written in Python?

PHP Parse error: syntax error, unexpected end of file in a CodeIgniter View

Usually the problem is not closing brackets (}) or missing semicolon (;)

How can I increment a date by one day in Java?

You can use this package from "org.apache.commons.lang3.time":

 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
 Date myNewDate = DateUtils.addDays(myDate, 4);
 Date yesterday = DateUtils.addDays(myDate, -1);
 String formatedDate = sdf.format(myNewDate);  

Pandas KeyError: value not in index

Use reindex to get all columns you need. It'll preserve the ones that are already there and put in empty columns otherwise.

p = p.reindex(columns=['1Sun', '2Mon', '3Tue', '4Wed', '5Thu', '6Fri', '7Sat'])

So, your entire code example should look like this:

df = pd.read_csv(CsvFileName)

p = df.pivot_table(index=['Hour'], columns='DOW', values='Changes', aggfunc=np.mean).round(0)
p.fillna(0, inplace=True)

columns = ["1Sun", "2Mon", "3Tue", "4Wed", "5Thu", "6Fri", "7Sat"]
p = p.reindex(columns=columns)
p[columns] = p[columns].astype(int)

Gradle Sync failed could not find constraint-layout:1.0.0-alpha2

Its available in androidx as following package

implementation "androidx.constraintlayout:constraintlayout:2.0.0-alpha1"

How to take character input in java

You can simply use (char); casting to char is necessary to convert int to char

Black transparent overlay on image hover with only CSS?

I'd suggest using a pseudo element in place of the overlay element. Because pseudo elements can't be added on enclosed img elements, you would still need to wrap the img element though.


<div class="image">
    <img src="" alt="" />

As for the CSS, set optional dimensions on the .image element, and relatively position it. If you are aiming for a responsive image, just omit the dimensions and this will still work (example). It's just worth noting that the dimensions must be on the parent element as opposed to the img element itself, see.

.image {
    position: relative;
    width: 400px;
    height: 400px;

Give the child img element a width of 100% of the parent and add vertical-align:top to fix the default baseline alignment issues.

.image img {
    width: 100%;
    vertical-align: top;

As for the pseudo element, set a content value and absolutely position it relative to the .image element. A width/height of 100% will ensure that this works with varying img dimensions. If you want to transition the element, set an opacity of 0 and add the transition properties/values.

.image:after {
    content: '\A';
    position: absolute;
    width: 100%; height:100%;
    top:0; left:0;
    opacity: 0;
    transition: all 1s;
    -webkit-transition: all 1s;

Use an opacity of 1 when hovering over the pseudo element in order to facilitate the transition:

.image:hover:after {
    opacity: 1;


If you want to add text on hover:

For the simplest approach, just add the text as the pseudo element's content value:


.image:after {
    content: 'Here is some text..';
    color: #fff;

    /* Other styling.. */

That should work in most instances; however, if you have more than one img element, you might not want the same text to appear on hover. You could therefore set the text in a data-* attribute and therefore have unique text for every img element.


.image:after {
    content: attr(data-content);
    color: #fff;

With a content value of attr(data-content), the pseudo element adds the text from the .image element's data-content attribute:

<div data-content="Text added on hover" class="image">
    <img src="" alt="" />

You can add some styling and do something like this:


In the above example, the :after pseudo element serves as the black overlay, while the :before pseudo element is the caption/text. Since the elements are independent of each other, you can use separate styling for more optimal positioning.

.image:after, .image:before {
    position: absolute;
    opacity: 0;
    transition: all 0.5s;
    -webkit-transition: all 0.5s;
.image:after {
    content: '\A';
    width: 100%; height:100%;
    top: 0; left:0;
.image:before {
    content: attr(data-content);
    width: 100%;
    color: #fff;
    z-index: 1;
    bottom: 0;
    padding: 4px 10px;
    text-align: center;
    background: #f00;
    box-sizing: border-box;
.image:hover:after, .image:hover:before {
    opacity: 1;

Get Date in YYYYMMDD format in windows batch file

If, after reading the other questions and viewing the links mentioned in the comment sections, you still can't figure it out, read on.

First of all, where you're going wrong is the offset.

It should look more like this...

set mydate=%date:~10,4%%date:~6,2%/%date:~4,2%
echo %mydate%

If the date was Tue 12/02/2013 then it would display it as 2013/02/12.

To remove the slashes, the code would look more like

set mydate=%date:~10,4%%date:~7,2%%date:~4,2%
echo %mydate%

which would output 20130212

And a hint for doing it in the future, if mydate equals something like %date:~10,4%%date:~7,2% or the like, you probably forgot a tilde (~).

How to check if a string in Python is in ASCII?

import re

def is_ascii(s):
    return bool(re.match(r'[\x00-\x7F]+$', s))

To include an empty string as ASCII, change the + to *.

How to add `style=display:"block"` to an element using jQuery?

Depending on the purpose of setting the display property, you might want to take a look at




How to do a newline in output

You can do this all in the block:

Dir.chdir 'C:/Users/name/Music'
music = Dir['C:/Users/name/Music/*.{mp3, MP3}']
puts 'what would you like to call the playlist?'
playlist_name = gets.chomp + '.m3u' playlist_name, 'w' do |f|
  music.each do |z|
    f.puts z

When should we use intern method of String on String literals

String p1 = "example";
String p2 = "example";
String p3 = "example".intern();
String p4 = p2.intern();
String p5 = new String(p3);
String p6 = new String("example");
String p7 = p6.intern();

if (p1 == p2)
    System.out.println("p1 and p2 are the same");
if (p1 == p3)
    System.out.println("p1 and p3 are the same");
if (p1 == p4)
    System.out.println("p1 and p4 are the same");
if (p1 == p5)
    System.out.println("p1 and p5 are the same");
if (p1 == p6)
    System.out.println("p1 and p6 are the same");
if (p1 == p6.intern())
    System.out.println("p1 and p6 are the same when intern is used");
if (p1 == p7)
    System.out.println("p1 and p7 are the same");

When two strings are created independently, intern() allows you to compare them and also it helps you in creating a reference in the string pool if the reference didn't exist before.

When you use String s = new String(hi), java creates a new instance of the string, but when you use String s = "hi", java checks if there is an instance of word "hi" in the code or not and if it exists, it just returns the reference.

Since comparing strings is based on reference, intern() helps in you creating a reference and allows you to compare the contents of the strings.

When you use intern() in the code, it clears of the space used by the string referring to the same object and just returns the reference of the already existing same object in memory.

But in case of p5 when you are using:

String p5 = new String(p3);

Only contents of p3 are copied and p5 is created newly. So it is not interned.

So the output will be:

p1 and p2 are the same
p1 and p3 are the same
p1 and p4 are the same
p1 and p6 are the same when intern is used
p1 and p7 are the same

How to set session timeout in web.config

Use this in web.config:



How can I get the latest JRE / JDK as a zip file rather than EXE or MSI installer?

  • Create destination folder where you can RWX (e.g. C:\jdk8)
  • Download jdk exe from Oracle (e.g. jdk-8u72-windows-x64.exe)
  • Unzip the found inside it into the destination folder
  • In cmd.exe, run:
    • cd C:\jdk8
    • for /r %x in (*.pack) do .\bin\unpack200 -r "%x" "%~dx%~px%~nx.jar"

This solution works for JDK 8 too, without Admin rights.

JavaScript alert not working in Android WebView

As others indicated, setting the WebChromeClient is needed to get alert() to work. It's sufficient to just set the default WebChromeClient():

mWebView.setWebChromeClient(new WebChromeClient());

Thanks for all the comments below. Including John Smith's who indicated that you needed to enable JavaScript.

Get RETURN value from stored procedure in SQL

Assign after the EXEC token:

DECLARE @returnValue INT

EXEC @returnValue = SP_One

How do I open phone settings when a button is clicked?

word of warning: the prefs:root or App-Prefs:root URL schemes are considered private API. Apple may reject you app if you use those, here is what you may get when submitting your app:

Your app uses the "prefs:root=" non-public URL scheme, which is a private entity. The use of non-public APIs is not permitted on the App Store because it can lead to a poor user experience should these APIs change. Continuing to use or conceal non-public APIs in future submissions of this app may result in the termination of your Apple Developer account, as well as removal of all associated apps from the App Store.

Next Steps

To resolve this issue, please revise your app to provide the associated functionality using public APIs or remove the functionality using the "prefs:root" or "App-Prefs:root" URL scheme.

If there are no alternatives for providing the functionality your app requires, you can file an enhancement request.

Removing a Fragment from the back stack

What happens if the fragment that you want to remove is not on top of the stack?

Then you can use theses functions

popBackStack(int arg0, int arg1);

popBackStack(String arg0, int arg1);

Send HTTP GET request with header

You do it exactly as you showed with this line:

get.setHeader("Content-Type", "application/x-zip");

So your header is fine and the problem is some other input to the web service. You'll want to debug that on the server side.

How to save a PNG image server-side, from a base64 data string

This code works for me check below code:

define('UPLOAD_DIR', 'images/');
$image_parts = explode(";base64,", $_POST['image']);
$image_type_aux = explode("image/", $image_parts[0]);
$image_type = $image_type_aux[1];
$image_base64 = base64_decode($image_parts[1]);
$file = UPLOAD_DIR . uniqid() . '.png';
file_put_contents($file, $image_base64);

What is the difference between null and System.DBNull.Value?

DBNull.Value is what the .NET Database providers return to represent a null entry in the database. DBNull.Value is not null and comparissons to null for column values retrieved from a database row will not work, you should always compare to DBNull.Value.

How do I get the currently-logged username from a Windows service in .NET?

This is a WMI query to get the user name:

ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT UserName FROM Win32_ComputerSystem");
ManagementObjectCollection collection = searcher.Get();
string username = (string)collection.Cast<ManagementBaseObject>().First()["UserName"];

You will need to add System.Management under References manually.

How to fix a collation conflict in a SQL Server query?

I had problems with collations as I had most of the tables with Modern_Spanish_CI_AS, but a few, which I had inherited or copied from another Database, had SQL_Latin1_General_CP1_CI_AS collation.

In my case, the easiest way to solve the problem has been as follows:

  1. I've created a copy of the tables which were 'Latin American, using script table as...
  2. The new tables have obviously acquired the 'Modern Spanish' collation of my database
  3. I've copied the data of my 'Latin American' table into the new one, deleted the old one and renamed the new one.

I hope this helps other users.

Understanding offsetWidth, clientWidth, scrollWidth and -Height, respectively

The CSS box model is rather complicated, particularly when it comes to scrolling content. While the browser uses the values from your CSS to draw boxes, determining all the dimensions using JS is not straight-forward if you only have the CSS.

That's why each element has six DOM properties for your convenience: offsetWidth, offsetHeight, clientWidth, clientHeight, scrollWidth and scrollHeight. These are read-only attributes representing the current visual layout, and all of them are integers (thus possibly subject to rounding errors).

Let's go through them in detail:

  • offsetWidth, offsetHeight: The size of the visual box incuding all borders. Can be calculated by adding width/height and paddings and borders, if the element has display: block
  • clientWidth, clientHeight: The visual portion of the box content, not including borders or scroll bars , but includes padding . Can not be calculated directly from CSS, depends on the system's scroll bar size.
  • scrollWidth, scrollHeight: The size of all of the box's content, including the parts that are currently hidden outside the scrolling area. Can not be calculated directly from CSS, depends on the content.

CSS2 Box Model

Try it out: jsFiddle

Since offsetWidth takes the scroll bar width into account, we can use it to calculate the scroll bar width via the formula

scrollbarWidth = offsetWidth - clientWidth - getComputedStyle().borderLeftWidth - getComputedStyle().borderRightWidth

Unfortunately, we may get rounding errors, since offsetWidth and clientWidth are always integers, while the actual sizes may be fractional with zoom levels other than 1.

Note that this

scrollbarWidth = getComputedStyle().width + getComputedStyle().paddingLeft + getComputedStyle().paddingRight - clientWidth

does not work reliably in Chrome, since Chrome returns width with scrollbar already substracted. (Also, Chrome renders paddingBottom to the bottom of the scroll content, while other browsers don't)

What is default color for text in textview?

You can save old color and then use it to restore the original value. Here is an example:

ColorStateList oldColors =  textView.getTextColors(); //save original colors
textView.setTextColor(oldColors);//restore original colors

But in general default TextView text color is determined from current Theme applied to your Activity.

How to remove the default link color of the html hyperlink 'a' tag?

I had this challenge when I was working on a Rails 6 application using Bootstrap 4.

My challenge was that I didn't want this styling to override the default link styling in the application.

So I created a CSS file called custom.css or custom.scss.

And then defined a new CSS rule with the following properties:

.remove_link_colour {
  a, a:hover, a:focus, a:active {
      color: inherit;
      text-decoration: none;

Then I called this rule wherever I needed to override the default link styling.

<div class="product-card__buttons">
  <button class="btn btn-success remove_link_colour" type="button"><%= link_to 'Edit', edit_product_path(product) %></button>
  <button class="btn btn-danger remove_link_colour" type="button"><%= link_to 'Destroy', product, method: :delete, data: { confirm: 'Are you sure?' } %></button>

This solves the issue of overriding the default link styling and removes the default colour, hover, focus, and active styling in the buttons only in places where I call the CSS rule.

That's all.

I hope this helps

Removing element from array in component state

Just a suggestion,in your code instead of using let newData = you could use spread which is introduced in ES6 that is you can uselet newData = for copying array

Three dots ... represents Spread Operators or Rest Parameters,

It allows an array expression or string or anything which can be iterating to be expanded in places where zero or more arguments for function calls or elements for array are expected.

Additionally you can delete item from array with following

onRemovePerson: function(index) {
  this.setState((prevState) => ({
    data: [,index),]

Hope this contributes!!

Select 2 columns in one and combine them

Yes it's possible, as long as the datatypes are compatible. If they aren't, use a CONVERT() or CAST()

SELECT firstname + ' ' + lastname AS name FROM customers

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

The default value for a Boolean (object) is null.
The default value for a boolean (primitive) is false.

Android Button setOnClickListener Design

I think you can usually do what you need in a loop, which is much better than many onClick methods if it can be done.

Check out this answer for a demonstration of how to use a loop for a similar problem. How you construct your loop will depend on the needs of your onClick functions and how similar they are to one another. The end result is much less repetitive code that is easier to maintain.

CSS-Only Scrollable Table with fixed headers

Surprised a solution using flexbox hasn't been posted yet.

Here's my solution using display: flex and a basic use of :after (thanks to Luggage) to maintain the alignment even with the scrollbar padding the tbody a bit. This has been verified in Chrome 45, Firefox 39, and MS Edge. It can be modified with prefixed properties to work in IE11, and further in IE10 with a CSS hack and the 2012 flexbox syntax.

Note the table width can be modified; this even works at 100% width.

The only caveat is that all table cells must have the same width. Below is a clearly contrived example, but this works fine when cell contents vary (table cells all have the same width and word wrapping on, forcing flexbox to keep them the same width regardless of content). Here is an example where cell contents are different.

Just apply the .scroll class to a table you want scrollable, and make sure it has a thead:

.scroll {_x000D_
  border: 0;_x000D_
  border-collapse: collapse;_x000D_
.scroll tr {_x000D_
  display: flex;_x000D_
.scroll td {_x000D_
  padding: 3px;_x000D_
  flex: 1 auto;_x000D_
  border: 1px solid #aaa;_x000D_
  width: 1px;_x000D_
  word-wrap: break-word;_x000D_
.scroll thead tr:after {_x000D_
  content: '';_x000D_
  overflow-y: scroll;_x000D_
  visibility: hidden;_x000D_
  height: 0;_x000D_
.scroll thead th {_x000D_
  flex: 1 auto;_x000D_
  display: block;_x000D_
  border: 1px solid #000;_x000D_
.scroll tbody {_x000D_
  display: block;_x000D_
  width: 100%;_x000D_
  overflow-y: auto;_x000D_
  height: 200px;_x000D_
<table class="scroll" width="400px">_x000D_

add string to String array

First, this code here,

string [] scripts = new String [] ("test3","test4","test5");

should be

String[] scripts = new String [] {"test3","test4","test5"};

Please read this tutorial on Arrays


Arrays are fixed size, so you can't add new Strings to above array. You may override existing values

scripts[0] = string1;


Create array with size then keep on adding elements till it is full.

If you want resizable arrays, consider using ArrayList.

How to add \newpage in Rmarkdown in a smart way?

In the initialization chunk I define a function

pagebreak <- function() {
    return('<div style="page-break-before: always;" />')

In the markdown part where I want to insert a page break, I type

`r pagebreak()`

Simulating a click in jQuery/JavaScript on a link

All this might not help say when you use rails remote form button to simulate click to. I tried to port nice event simulation from prototype here: my snippets. Just did it and it works for me.

How can I generate a list of files with their absolute path in Linux?

Command: ls -1 -d "$PWD/"*

This will give the absolute paths of the file like below.

[root@kubenode1 ssl]# ls -1 -d "$PWD/"*

Java's L number (long) specification

It seems like these would be good to have because (I assume) if you could specify the number you're typing in is a short then java wouldn't have to cast it

Since the parsing of literals happens at compile time, this is absolutely irrelevant in regard to performance. The only reason having short and byte suffixes would be nice is that it lead to more compact code.

How can I solve the error LNK2019: unresolved external symbol - function?

Check the character set of both projects in Configuration Properties ? General ? Character Set.

My UnitTest project was using the default character set Multi-Byte while my libraries were in Unicode.

My function was using a TCHAR as a parameter.

As a result, in my library my TCHAR was transformed into a WCHAR, but it was a char* in my UnitTest: the symbol was different because the parameters were really not the same in the end.

WPF Button with Image

Most simple approach would be using the Image tag.

<Button Name="btn" Width="26" Height="26" Click="btnClick"> 
   <Image Source="Resource/btn-icon.png"/>

Suppose your image file is added in Resource folder

java.lang.ClassNotFoundException: org.apache.log4j.Level

You need to download log4j and add in your classpath.

How to create JSON string in C#

Take a look at for the json-net.aspx project. Why re-invent the wheel?

Creation timestamp and last update timestamp with Hibernate and MySQL

A good approach is to have a common base class for all your entities. In this base class, you can have your id property if it is commonly named in all your entities (a common design), your creation and last update date properties.

For the creation date, you simply keep a java.util.Date property. Be sure, to always initialize it with new Date().

For the last update field, you can use a Timestamp property, you need to map it with @Version. With this Annotation the property will get updated automatically by Hibernate. Beware that Hibernate will also apply optimistic locking (it's a good thing).

Parse JSON with R

RJSONIO from Omegahat is another package which provides facilities for reading and writing data in JSON format.

rjson does not use S4/S3 methods and so is not readily extensible, but still useful. Unfortunately, it does not used vectorized operations and so is too slow for non-trivial data. Similarly, for reading JSON data into R, it is somewhat slow and so does not scale to large data, should this be an issue.

Update (new Package 2013-12-03):

jsonlite: This package is a fork of the RJSONIO package. It builds on the parser from RJSONIO but implements a different mapping between R objects and JSON strings. The C code in this package is mostly from the RJSONIO Package, the R code has been rewritten from scratch. In addition to drop-in replacements for fromJSON and toJSON, the package has functions to serialize objects. Furthermore, the package contains a lot of unit tests to make sure that all edge cases are encoded and decoded consistently for use with dynamic data in systems and applications.

Simulate string split function in Excel formula

Highlight the cell, use Dat => Text to Columns and the DELIMITER is space. Result will appear in as many columns as the split find the space.

What is the exact meaning of Git Bash?

I think the question asker is (was) thinking that git bash is a command like git init or git checkout. Git bash is not a command, it is an interface. I will also assume the asker is not a linux user because bash is very popular the unix/linux world. The name "bash" is an acronym for "Bourne Again SHell". Bash is a text-only command interface that has features which allow automated scripts to be run. A good analogy would be to compare bash to the new PowerShell interface in Windows7/8. A poor analogy (but one likely to be more readily understood by more people) is the combination of the command prompt and .BAT (batch) command files from the days of DOS and early versions of Windows.


Difference between AutoPostBack=True and AutoPostBack=False?

There is one event which is default associate with any webcontrol. For example, in case of Button click event, in case of Check box CheckChangedEvent is there. So in case of AutoPostBack true these events are called by default and event handle at server side.

MySQL timezone change?

The easiest way to do this, as noted by Umar is, for example

mysql> SET GLOBAL time_zone = 'America/New_York';

Using the named timezone is important for timezone that has a daylights saving adjustment. However, for some linux builds you may get the following response:

#1298 - Unknown or incorrect time zone

If you're seeing this, you may need to run a tzinfo_to_sql translation... it's easy to do, but not obvious. From the linux command line type in:

mysql_tzinfo_to_sql /usr/share/zoneinfo/|mysql -u root mysql -p

Provide your root password (MySQL root, not Linux root) and it will load any definitions in your zoneinfo into mysql. You can then go back and run your

mysql> SET GLOBAL time_zone = timezone;

Setting up SSL on a local xampp/apache server

Apache part - enabling you to open https://localhost/xyz

There is the config file xampp/apache/conf/extra/httpd-ssl.conf which contains all the ssl specific configuration. It's fairly well documented, so have a read of the comments and take look at The files starts with <IfModule ssl_module>, so it only has an effect if the apache has been started with its mod_ssl module.

Open the file xampp/apache/conf/httpd.conf in an editor and search for the line

#LoadModule ssl_module modules/

remove the hashmark, save the file and re-start the apache. The webserver should now start with xampp's basic/default ssl confguration; good enough for testing but you might want to read up a bit more about mod_ssl in the apache documentation.

PHP part - enabling adldap to use ldap over ssl

adldap needs php's openssl extension to use "ldap over ssl" connections. The openssl extension ships as a dll with xampp. You must "tell" php to load this dll, e.g. by having an extension=nameofmodule.dll in your php.ini

echo 'ini: ', get_cfg_var('cfg_file_path');

It should show you which ini file your php installation uses (may differ between the php-apache-module and the php-cli version).
Open this file in an editor and search for


remove the semicolon, save the file and re-start the apache.

see also:

Cross origin requests are only supported for HTTP but it's not cross-domain

It works best this way. Make sure that both files are on the server. When calling the html page, make use of the web address like: http:://localhost/myhtmlfile.html, and not, C::///users/myhtmlfile.html. Make usre as well that the url passed to the json is a web address as denoted below:

                    source: function(query, process){
                            url: 'http://localhost:2222/bootstrap/source.php',
                            type: 'POST',
                            data: 'query=' +query,
                            dataType: 'JSON',
                            async: true,
                            success: function(data){

How to create a dotted <hr/> tag?

The <hr> tag is just a short element with a border:

<hr style="border-style: dotted;" />

C# elegant way to check if a property's property is null

I wrote a method that accepts a default value, here is how to use it:

var teacher = new Teacher();
return teacher.GetProperty(t => t.Name);
return teacher.GetProperty(t => t.Name, "Default name");

Here is the code:

public static class Helper
    /// <summary>
    /// Gets a property if the object is not null.
    /// var teacher = new Teacher();
    /// return teacher.GetProperty(t => t.Name);
    /// return teacher.GetProperty(t => t.Name, "Default name");
    /// </summary>
    public static TSecond GetProperty<TFirst, TSecond>(this TFirst item1,
        Func<TFirst, TSecond> getItem2, TSecond defaultValue = default(TSecond))
        if (item1 == null)
            return defaultValue;

        return getItem2(item1);

Using Java to find substring of a bigger string using Regular Expression

This is a working example :

package org.regexp.replace;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexpExample
    public static void main(String[] args)
        String string = "var1[value1], var2[value2], var3[value3]";
        Pattern pattern = Pattern.compile("(\\[)(.*?)(\\])");
        Matcher matcher = pattern.matcher(string);

        List<String> listMatches = new ArrayList<String>();


        for(String s : listMatches)

It displays :


Difference between \n and \r?

Historically a \n was used to move the carriage down, while the \r was used to move the carriage back to the left side of the page.

How to count days between two dates in PHP?

In case your DateTime has also hour:minutes:seconds and you still want to have the number of days..

     * Returns the total number of days between to DateTimes, 
     * if it is within the same year
     * @param $start
     * @param $end
    public function dateTimesToDays($start,$end){
       return intval($end->format('z')) - intval($start->format('z')) + 1;

How to get the selected row values of DevExpress XtraGrid?

You can do this in a number of ways. You can use databinding (typical initialized after InitializeComponent();)

textBox1.DataBindings.Add(new Binding("Text", yourBindingSource, 
                    "TableName.ColumnName", true, DataSourceUpdateMode.OnPropertyChanged));

or use a DataLayoutControl (if you are going to use textbox for editing, I really recommend spending some time to learn how to use this component.

or in FocusedRowChanged by assigning from one of these methods:

textBox1.Text = gridView1.GetDataRow(e.FocusedRowHandle)["Name"].ToString();
textBox1.Text = gridView1.GetFocusedDataRow()["Name"].ToString();
textBox1.Text = (gridView1.GetFocusedRow() as DataRowView).Row["Name"].ToString();
textBox1.Text = gridView1.GetFocusedRowCellValue("Name").ToString();

How to split a list by comma not space

Create a bash function

split_on_commas() {
  local IFS=,
  local WORD_LIST=($1)
  for word in "${WORD_LIST[@]}"; do
    echo "$word"

split_on_commas "this,is a,list" | while read item; do
  # Custom logic goes here
  echo Item: ${item}

... this generates the following output:

Item: this
Item: is a
Item: list

(Note, this answer has been updated according to some feedback)

How to declare a Fixed length Array in TypeScript

The Tuple approach :

This solution provides a strict FixedLengthArray (ak.a. SealedArray) type signature based in Tuples.

Syntax example :

// Array containing 3 strings
let foo : FixedLengthArray<[string, string, string]> 

This is the safest approach, considering it prevents accessing indexes out of the boundaries.

Implementation :

type ArrayLengthMutationKeys = 'splice' | 'push' | 'pop' | 'shift' | 'unshift' | number
type ArrayItems<T extends Array<any>> = T extends Array<infer TItems> ? TItems : never
type FixedLengthArray<T extends any[]> =
  Pick<T, Exclude<keyof T, ArrayLengthMutationKeys>>
  & { [Symbol.iterator]: () => IterableIterator< ArrayItems<T> > }

Tests :

var myFixedLengthArray: FixedLengthArray< [string, string, string]>

// Array declaration tests
myFixedLengthArray = [ 'a', 'b', 'c' ]  // ? OK
myFixedLengthArray = [ 'a', 'b', 123 ]  // ? TYPE ERROR
myFixedLengthArray = [ 'a' ]            // ? LENGTH ERROR
myFixedLengthArray = [ 'a', 'b' ]       // ? LENGTH ERROR

// Index assignment tests 
myFixedLengthArray[1] = 'foo'           // ? OK
myFixedLengthArray[1000] = 'foo'        // ? INVALID INDEX ERROR

// Methods that mutate array length
myFixedLengthArray.push('foo')          // ? MISSING METHOD ERROR
myFixedLengthArray.pop()                // ? MISSING METHOD ERROR

// Direct length manipulation
myFixedLengthArray.length = 123         // ? READ-ONLY ERROR

// Destructuring
var [ a ] = myFixedLengthArray          // ? OK
var [ a, b ] = myFixedLengthArray       // ? OK
var [ a, b, c ] = myFixedLengthArray    // ? OK
var [ a, b, c, d ] = myFixedLengthArray // ? INVALID INDEX ERROR

(*) This solution requires the noImplicitAny typescript configuration directive to be enabled in order to work (commonly recommended practice)

The Array(ish) approach :

This solution behaves as an augmentation of the Array type, accepting an additional second parameter(Array length). Is not as strict and safe as the Tuple based solution.

Syntax example :

let foo: FixedLengthArray<string, 3> 

Keep in mind that this approach will not prevent you from accessing an index out of the declared boundaries and set a value on it.

Implementation :

type ArrayLengthMutationKeys = 'splice' | 'push' | 'pop' | 'shift' |  'unshift'
type FixedLengthArray<T, L extends number, TObj = [T, ...Array<T>]> =
  Pick<TObj, Exclude<keyof TObj, ArrayLengthMutationKeys>>
  & {
    readonly length: L 
    [ I : number ] : T
    [Symbol.iterator]: () => IterableIterator<T>   

Tests :

var myFixedLengthArray: FixedLengthArray<string,3>

// Array declaration tests
myFixedLengthArray = [ 'a', 'b', 'c' ]  // ? OK
myFixedLengthArray = [ 'a', 'b', 123 ]  // ? TYPE ERROR
myFixedLengthArray = [ 'a' ]            // ? LENGTH ERROR
myFixedLengthArray = [ 'a', 'b' ]       // ? LENGTH ERROR

// Index assignment tests 
myFixedLengthArray[1] = 'foo'           // ? OK
myFixedLengthArray[1000] = 'foo'        // ? SHOULD FAIL

// Methods that mutate array length
myFixedLengthArray.push('foo')          // ? MISSING METHOD ERROR
myFixedLengthArray.pop()                // ? MISSING METHOD ERROR

// Direct length manipulation
myFixedLengthArray.length = 123         // ? READ-ONLY ERROR

// Destructuring
var [ a ] = myFixedLengthArray          // ? OK
var [ a, b ] = myFixedLengthArray       // ? OK
var [ a, b, c ] = myFixedLengthArray    // ? OK
var [ a, b, c, d ] = myFixedLengthArray // ? SHOULD FAIL

How to use HTTP_X_FORWARDED_FOR properly?

You can also solve this problem via Apache configuration using mod_remoteip, by adding the following to a conf.d file:

RemoteIPHeader X-Forwarded-For
LogFormat "%a %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined

cordova run with ios error .. Error code 65 for command: xcodebuild with args:

Same problem for me today, with "ARCHIVE FAILED". None of the solutions above worked for me, but watching closer, the error refers the path of module cordova-plugin-inappbrowser, so i removed the plugin, then added it again, and it finally works...

ionic cordova plugin remove cordova-plugin-inappbrowser
ionic cordova plugin add cordova-plugin-inappbrowser

stack :

Ionic cli 6.2.2
Ionic1 1.3.2
Cordova cli 9.0.0
Cordova platform ios 5.1.1
cordova-plugin-inappbrowser 3.2.0

make UITableViewCell selectable only while editing

Have you tried setting the selection properties of your tableView like this:

tableView.allowsMultipleSelection = NO; tableView.allowsMultipleSelectionDuringEditing = YES; tableView.allowsSelection = NO; tableView.allowsSelectionDuringEditing YES; 

If you want more fine-grain control over when selection is allowed you can override - (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath in your UITableView delegate. The documentation states:

Return Value An index-path object that confirms or alters the selected row. Return an NSIndexPath object other than indexPath if you want another cell to be selected. Return nil if you don't want the row selected. 

You can have this method return nil in cases where you don't want the selection to happen.

Re-order columns of table in Oracle

Look at the package DBMS_Redefinition. It will rebuild the table with the new ordering. It can be done with the table online.

As Phil Brown noted, think carefully before doing this. However there is overhead in scanning the row for columns and moving data on update. Column ordering rules I use (in no particular order):

  • Group related columns together.
  • Not NULL columns before null-able columns.
  • Frequently searched un-indexed columns first.
  • Rarely filled null-able columns last.
  • Static columns first.
  • Updateable varchar columns later.
  • Indexed columns after other searchable columns.

These rules conflict and have not all been tested for performance on the latest release. Most have been tested in practice, but I didn't document the results. Placement options target one of three conflicting goals: easy to understand column placement; fast data retrieval; and minimal data movement on updates.

What is the best/safest way to reinstall Homebrew?

For me, this one worked without the sudo access.

ruby -e "$(curl -fsSL"

For more reference, please follow

enter image description here

Maven home (M2_HOME) not being picked up by IntelliJ IDEA

Mac OS apps cannot read bash environment variables. Look at this question Setting environment variables in OS X? to expose M2_HOME to all applications including IntelliJ. You do need to restart after doing this.

PDO mysql: How to know if insert was successful

Try looking at the return value of execute, which is TRUE on success, and FALSE on failure.

How to correctly catch change/focusOut event on text input in React.js?

Its late, yet it's worth your time nothing that, there are some differences in browser level implementation of focusin and focusout events and react synthetic onFocus and onBlur. focusin and focusout actually bubble, while onFocus and onBlur dont. So there is no exact same implementation for focusin and focusout as of now for react. Anyway most cases will be covered in onFocus and onBlur.

++i or i++ in for loops ??

++i is a pre-increment; i++ is post-increment.
The downside of post-increment is that it generates an extra value; it returns a copy of the old value while modifying i. Thus, you should avoid it when possible.

Batch not-equal (inequality) operator

I know this is quite out of date, but this might still be useful for those coming late to the party. (EDIT: updated since this still gets traffic and @Goozak has pointed out in the comments that my original analysis of the sample was incorrect as well.)

I pulled this from the example code in your link:




!%1==! is simply an idiomatic use of == intended to verify that the thing on the left, that contains your variable, is different from the thing on the right, that does not. The ! in this case is just a character placeholder. It could be anything. If %1 has content, then the equality will be false, if it does not you'll just be comparing ! to ! and it will be true.

!==! is not an operator, so writing "asdf" !==! "fdas" is pretty nonsensical.

The suggestion to use if not "asdf" == "fdas" is definitely the way to go.

Prompt Dialog in Windows Forms

Other way of doing this: Assuming that you have a TextBox input type, Create a Form, and have the textbox value as a public property.

public partial class TextPrompt : Form
    public string Value
        get { return tbText.Text.Trim(); }

    public TextPrompt(string promptInstructions)

        lblPromptText.Text = promptInstructions;

    private void BtnSubmitText_Click(object sender, EventArgs e)

    private void TextPrompt_Load(object sender, EventArgs e)

In the main form, this will be the code:

var t = new TextPrompt(this, "Type the name of the settings file:");


This way, the code looks cleaner:

  1. If validation logic is added.
  2. If various other input types are added.

Programmatically Install Certificate into Mozilla

Here is an alternative way that doesn't override the existing certificates: [bash fragment for linux systems]

certificateName="MyCA Name" 
for certDB in $(find  ~/.mozilla* ~/.thunderbird -name "cert8.db")
  certDir=$(dirname ${certDB});
  #log "mozilla certificate" "install '${certificateName}' in ${certDir}"
  certutil -A -n "${certificateName}" -t "TCu,Cuw,Tuw" -i ${certificateFile} -d ${certDir}

You may find certutil in the libnss3-tools package (debian/ubuntu).


See also:

Styling input buttons for iPad and iPhone

Use the below css

input[type="submit"] {_x000D_
  font-size: 20px;_x000D_
  background: pink;_x000D_
  border: none;_x000D_
  padding: 10px 20px;_x000D_
.flat-btn {_x000D_
  -webkit-appearance: none;_x000D_
  -moz-appearance: none;_x000D_
   appearance: none;_x000D_
   border-radius: 0;_x000D_
h2 {_x000D_
  margin: 25px 0 10px;_x000D_
  font-size: 20px;_x000D_
<h2>iOS Styled Button!</h2>_x000D_
<input type="submit" value="iOS Styled Button!" />_x000D_
<h2>No More Style! Button!</h2>_x000D_
<input class="flat-btn" type="submit" value="No More Style! Button!" />

"Expected BEGIN_OBJECT but was STRING at line 1 column 1"

I had a similar problem recently and found an interesting solution. Basically I needed to deserialize following nested JSON String into my POJO:

"{\"restaurant\":{\"id\":\"abc-012\",\"name\":\"good restaurant\",\"foodType\":\"American\",\"phoneNumber\":\"123-456-7890\",\"currency\":\"USD\",\"website\":\"\",\"location\":{\"address\":{\"street\":\" Good Street\",\"city\":\"Good City\",\"state\":\"CA\",\"country\":\"USA\",\"postalCode\":\"12345\"},\"coordinates\":{\"latitude\":\"00.7904692\",\"longitude\":\"-000.4047208\"}},\"restaurantUser\":{\"firstName\":\"test\",\"lastName\":\"test\",\"email\":\"[email protected]\",\"title\":\"server\",\"phone\":\"0000000000\"}}}"

I ended up using regex to remove the open quotes from beginning and the end of JSON and then used apache.commons unescapeJava() method to unescape it. Basically passed the unclean JSON into following method to get back a cleansed one:

private String removeQuotesAndUnescape(String uncleanJson) {
    String noQuotes = uncleanJson.replaceAll("^\"|\"$", "");

    return StringEscapeUtils.unescapeJava(noQuotes);

then used Google GSON to parse it into my own Object:

MyObject myObject = new.Gson().fromJson(this.removeQuotesAndUnescape(uncleanJson));

Which browsers support <script async="async" />?

Just had a look at the DOM (document.scripts[1].attributes) of this page that uses google analytics. I can tell you that google is using async="".

[type="text/javascript", async="", src=""]

Converting xml to string using C#

There's a much simpler way to convert your XmlDocument to a string; use the OuterXml property. The OuterXml property returns a string version of the xml.

public string GetXMLAsString(XmlDocument myxml)
    return myxml.OuterXml;

PHP, display image with Header()

There is a better why to determine type of an image. with exif_imagetype

If you use this function, you can tell image's real extension.

with this function filename's extension is completely irrelevant, which is good.

function setHeaderContentType(string $filePath): void
    $numberToContentTypeMap = [
        '1' => 'image/gif',
        '2' => 'image/jpeg',
        '3' => 'image/png',
        '6' => 'image/bmp',
        '17' => 'image/ico'

    $contentType = $numberToContentTypeMap[exif_imagetype($filePath)] ?? null;
    if ($contentType === null) {
        throw new Exception('Unable to determine content type of file.');

    header("Content-type: $contentType");

You can add more types from the link.

Hope it helps.

Gets byte array from a ByteBuffer in java

Depends what you want to do.

If what you want is to retrieve the bytes that are remaining (between position and limit), then what you have will work. You could also just do:

ByteBuffer bb =..

byte[] b = new byte[bb.remaining()];

which is equivalent as per the ByteBuffer javadocs.

Adding backslashes without escaping [Python]

There is no extra backslash, it's just formatted that way in the interactive environment. Try:

print string

Then you can see that there really is no extra backslash.

Get Line Number of certain phrase in file Python

Here's what I've found to work:

f_rd = open(path, 'r')
file_lines = f_rd.readlines()

matches = [line for line in file_lines if "chars of Interest" in line]
index = file_lines.index(matches[0])

MSVCP140.dll missing

That's probably the C++ runtime library. Since it's a DLL it is not included in your program executable. Your friend can download those libraries from Microsoft.

Validating a Textbox field for only numeric input.

Here's a solution that allows either numeric only with a minus sign or decimal with a minus sign and decimal point. Most of the previous answers did not take into account selected text. If you change your textbox's ShortcutsEnabled to false, then you can't paste garbage into your textbox either (it disables right-clicking). Some solutions allowed you to enter data before the minus. Please verify that I've caught everything!

        private bool DecimalOnly_KeyPress(TextBox txt, bool numeric, KeyPressEventArgs e)
            if (numeric)
                // Test first character - either text is blank or the selection starts at first character.
                if (txt.Text == "" || txt.SelectionStart == 0)
                    // If the first character is a minus or digit, AND
                    // if the text does not contain a minus OR the selected text DOES contain a minus.
                    if ((e.KeyChar == '-' || char.IsDigit(e.KeyChar)) && (!txt.Text.Contains("-") || txt.SelectedText.Contains("-")))
                        return false;
                        return true;
                    // If it's not the first character, then it must be a digit or backspace
                    if (char.IsDigit(e.KeyChar) || e.KeyChar == Convert.ToChar(Keys.Back))
                        return false;
                        return true;
                // Test first character - either text is blank or the selection starts at first character.
                if (txt.Text == "" || txt.SelectionStart == 0)
                    // If the first character is a minus or digit, AND
                    // if the text does not contain a minus OR the selected text DOES contain a minus.
                    if ((e.KeyChar == '-' || char.IsDigit(e.KeyChar)) && (!txt.Text.Contains("-") || txt.SelectedText.Contains("-")))
                        return false;
                        // If the first character is a decimal point or digit, AND
                        // if the text does not contain a decimal point OR the selected text DOES contain a decimal point.
                        if ((e.KeyChar == '.' || char.IsDigit(e.KeyChar)) && (!txt.Text.Contains(".") || txt.SelectedText.Contains(".")))
                            return false;
                            return true;
                    // If it's not the first character, then it must be a digit or backspace OR
                    // a decimal point AND
                    // if the text does not contain a decimal point or the selected text does contain a decimal point.
                    if (char.IsDigit(e.KeyChar) || e.KeyChar == Convert.ToChar(Keys.Back) || (e.KeyChar == '.' && (!txt.Text.Contains(".") || txt.SelectedText.Contains("."))))
                        return false;
                        return true;


initialize a vector to zeros C++/C++11

Initializing a vector having struct, class or Union can be done this way

std::vector<SomeStruct> someStructVect(length);
memset(, 0, sizeof(SomeStruct)*length);

Get latitude and longitude based on location name with Google Autocomplete API

Enter the location by Autocomplete and rest of all the fields: latitude and Longititude values get automatically filled.
Replace API KEY with your Google API key

<meta name="viewport" content="initial-scale=1.0, user-scalable=no">
<meta charset="utf-8">
<script src=""></script>

<link type="text/css" rel="stylesheet" href=",400,500">

<textarea placeholder="Enter Area name to populate Latitude and Longitude" name="address" onFocus="initializeAutocomplete()" id="locality" ></textarea><br>

<input type="text" name="city" id="city" placeholder="City" value="" ><br>
<input type="text" name="latitude" id="latitude" placeholder="Latitude" value="" ><br>
<input type="text" name="longitude" id="longitude" placeholder="Longitude" value="" ><br>
<input type="text" name="place_id" id="location_id" placeholder="Location Ids" value="" ><br>

<script type="text/javascript">
  function initializeAutocomplete(){
    var input = document.getElementById('locality');
    // var options = {
    //   types: ['(regions)'],
    //   componentRestrictions: {country: "IN"}
    // };
    var options = {}

    var autocomplete = new google.maps.places.Autocomplete(input, options);

    google.maps.event.addListener(autocomplete, 'place_changed', function() {
      var place = autocomplete.getPlace();
      var lat =;
      var lng = place.geometry.location.lng();
      var placeId = place.place_id;
      // to set city name, using the locality param
      var componentForm = {
        locality: 'short_name',
      for (var i = 0; i < place.address_components.length; i++) {
        var addressType = place.address_components[i].types[0];
        if (componentForm[addressType]) {
          var val = place.address_components[i][componentForm[addressType]];
          document.getElementById("city").value = val;
      document.getElementById("latitude").value = lat;
      document.getElementById("longitude").value = lng;
      document.getElementById("location_id").value = placeId;

<script src=""></script>
<script src="// KEY"></script>

<script src=",400,500></script>

Interpreting segfault messages

This is a segfault due to following a null pointer trying to find code to run (that is, during an instruction fetch).

If this were a program, not a shared library

Run addr2line -e yourSegfaultingProgram 00007f9bebcca90d (and repeat for the other instruction pointer values given) to see where the error is happening. Better, get a debug-instrumented build, and reproduce the problem under a debugger such as gdb.

Since it's a shared library

You're hosed, unfortunately; it's not possible to know where the libraries were placed in memory by the dynamic linker after-the-fact. Reproduce the problem under gdb.

What the error means

Here's the breakdown of the fields:

  • address (after the at) - the location in memory the code is trying to access (it's likely that 10 and 11 are offsets from a pointer we expect to be set to a valid value but which is instead pointing to 0)
  • ip - instruction pointer, ie. where the code which is trying to do this lives
  • sp - stack pointer
  • error - An error code for page faults; see below for what this means on x86.

     * Page fault error code bits:
     *   bit 0 ==    0: no page found       1: protection fault
     *   bit 1 ==    0: read access         1: write access
     *   bit 2 ==    0: kernel-mode access  1: user-mode access
     *   bit 3 ==                           1: use of reserved bit detected
     *   bit 4 ==                           1: fault was an instruction fetch

powershell mouse move does not prevent idle mode

There is an analog solution to this also. There's an android app called "Timeout Blocker" that vibrates at a set interval and you put your mouse on it.

How to execute Python scripts in Windows?

Simply run the command:

C:>python .\

Assuming the file name is within same folder and Python has already been added to environment variables.

Calling Web API from MVC controller

Its very late here but thought to share below code. If we have our WebApi as a different project altogether in the same solution then we can call the same from MVC controller like below

public class ProductsController : Controller
        // GET: Products
        public async Task<ActionResult> Index()
            string apiUrl = "http://localhost:58764/api/values";

            using (HttpClient client=new HttpClient())
                client.BaseAddress = new Uri(apiUrl);
                client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));

                HttpResponseMessage response = await client.GetAsync(apiUrl);
                if (response.IsSuccessStatusCode)
                    var data = await response.Content.ReadAsStringAsync();
                    var table = Newtonsoft.Json.JsonConvert.DeserializeObject<System.Data.DataTable>(data);


            return View();


MVC 4 @Scripts "does not exist"

I ran into this problem, however while running the command:

Install-Package -IncludePrerelease Microsoft.AspNet.Web.Optimization 

I received the cryptic message (gotta love a great pun before the first cup of coffee):

Install-Package : The specified cryptographic algorithm is not supported on this platform.

I am running this on Windows XP SP3 (not by choice) and what I found was that I had to follow the instructions posted by the user artsnob on the ASP.NET Forum

  • Please uninstall the Nuget and try re-installing it. If you are unable to do this, login as an Administrator.
  • Go to Tools=> Extension Manager => Select "Nuget Package Manager" => UnInstall
  • Install it again, by searching "Nuget" => Install.
  • If it did not work, please try installing, 1.7.x version as I mentioned in the previous post (It doesn't mean, you have to use the previous version, if it works fine, we can report this bug, and get the patches for the latest version).

Once I ran this I could then run the command line to update the Web.Optimization.

Hope this saves someone some digging.

Output a NULL cell value in Excel

As you've indicated, you can't output NULL in an excel formula. I think this has to do with the fact that the formula itself causes the cell to not be able to be NULL. "" is the next best thing, but sometimes it's useful to use 0.


Based on your comment, you might want to check out this link.

It goes in depth on the graphing issues and what the various values represent, and how to manipulate their output on a chart.

I'm not familiar with VSTO I'm afraid. So I won't be much help there. But if you are really placing formulas in the cell, then there really is no way. ISBLANK() only tests to see if a cell is blank or not, it doesn't have a way to make it blank. It's possible to write code in VBA (and VSTO I imagine) that would run on a worksheet_change event and update the various values instead of using formulas. But that would be cumbersome and performance would take a hit.

Java: Difference between the setPreferredSize() and setSize() methods in components

Usage depends on whether the component's parent has a layout manager or not.

  • setSize() -- use when a parent layout manager does not exist;
  • setPreferredSize() (also its related setMinimumSize and setMaximumSize) -- use when a parent layout manager exists.

The setSize() method probably won't do anything if the component's parent is using a layout manager; the places this will typically have an effect would be on top-level components (JFrames and JWindows) and things that are inside of scrolled panes. You also must call setSize() if you've got components inside a parent without a layout manager.

Generally, setPreferredSize() will lay out the components as expected if a layout manager is present; most layout managers work by getting the preferred (as well as minimum and maximum) sizes of their components, then using setSize() and setLocation() to position those components according to the layout's rules.

For example, a BorderLayout tries to make the bounds of its "north" region equal to the preferred size of its north component---they may end up larger or smaller than that, depending on the size of the JFrame, the size of the other components in the layout, and so on.

How to convert a string to integer in C?

Just wanted to share a solution for unsigned long aswell.

unsigned long ToUInt(char* str)
    unsigned long mult = 1;
    unsigned long re = 0;
    int len = strlen(str);
    for(int i = len -1 ; i >= 0 ; i--)
        re = re + ((int)str[i] -48)*mult;
        mult = mult*10;
    return re;

How to use GROUP BY to concatenate strings in MySQL?

The result is truncated to the maximum length that is given by the group_concat_max_len system variable, which has a default value of 1024 characters, so we first do:

SET group_concat_max_len=100000000;

and then, for example:

SELECT pub_id,GROUP_CONCAT(cate_id SEPARATOR ' ') FROM book_mast GROUP BY pub_id

JUnit: how to avoid "no runnable methods" in test utils classes

To prevent JUnit from instantiating your test base class just make it

public abstract class MyTestBaseClass { ... whatever... }

(@Ignore reports it as ignored which I reserve for temporarily ignored tests.)

Python's "in" set operator

Sets behave different than dicts, you need to use set operations like issubset():

>>> k
{'ip': '', 'pw': 'test1234', 'port': 1234, 'debug': True}
>>> set('ip,port,pw'.split(',')).issubset(set(k.keys()))
>>> set('ip,port,pw'.split(',')) in set(k.keys())

How do I check if an element is hidden in jQuery?

To check if it is not visible I use !:

if ( !$('#book').is(':visible')) {
    alert('#book is not visible')

Or the following is also the sam, saving the jQuery selector in a variable to have better performance when you need it multiple times:

var $book = $('#book')

if(!$':visible')) {
    alert('#book is not visible')

Set keyboard caret position in html textbox

I've adjusted the answer of kd7 a little bit because elem.selectionStart will evaluate to false when the selectionStart is incidentally 0.

function setCaretPosition(elem, caretPos) {
    var range;

    if (elem.createTextRange) {
        range = elem.createTextRange();
        range.move('character', caretPos);;
    } else {
        if (elem.selectionStart !== undefined) {
            elem.setSelectionRange(caretPos, caretPos);

com.jcraft.jsch.JSchException: UnknownHostKey

JSch jsch = new JSch();
Session session = null;
try {
session = jsch.getSession("user", "hostname", 22); // default
UserInfo ui = new MyUserInfo();
java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
Channel channel = session.openChannel("sftp");
} catch (JSchException e) {
} catch (Exception e) {
} finally {

How to clean node_modules folder of packages that are not in package.json?

For Windows User, alternative solution to remove such folder listed here:

Among them, a free tool: Long Path Fixer is good to try:

.NET obfuscation tools/strategy

I had to use a obfuscation/resource protection in my latest rpoject and found Crypto Obfuscator as a nice and simple to use tool. The serialization issue is only a matter of settings in this tool.

What is the best way to connect and use a sqlite database from C#

Mono comes with a wrapper, use theirs! gives code to wrap the actual SQLite dll ( found on the download page ) in a .net friendly way. It works on Linux or Windows.

This seems the thinnest of all worlds, minimizing your dependence on third party libraries. If I had to do this project from scratch, this is the way I would do it.

Grant Select on all Tables Owned By Specific User

tables + views + error reporting

  o_type VARCHAR2(60) := '';
  o_name VARCHAR2(60) := '';
  o_owner VARCHAR2(60) := '';
  l_error_message VARCHAR2(500) := '';
  FOR R IN (SELECT owner, object_type, object_name
            FROM all_objects 
            WHERE owner='SCHEMANAME'
            AND object_type IN ('TABLE','VIEW')
            ORDER BY 1,2,3) LOOP
    o_type := r.object_type;
    o_owner := r.owner;
    o_name := r.object_name;
    DBMS_OUTPUT.PUT_LINE(o_type||' '||o_owner||'.'||o_name);
    EXECUTE IMMEDIATE 'grant select on '||o_owner||'.'||o_name||' to USERNAME';
        l_error_message := sqlerrm;
        DBMS_OUTPUT.PUT_LINE('Error with '||o_type||' '||o_owner||'.'||o_name||': '|| l_error_message);

Run Java Code Online

Zamples is another site where you write a java code and run it online. Here you have possibility to choose jdk version also.

How to remove new line characters from data rows in mysql?

your syntax is wrong:

update mytable SET title = TRIM(TRAILING '\n' FROM title)


If the newline character is at the start of the field:

update mytable SET title = TRIM(LEADING '\n' FROM title)

Pass values of checkBox to controller action in mvc4

None of the previous solutions worked for me. Finally I found that the action should be coded as:

public ActionResult Index(string MyCheck = null)

and then, when checked the passed value was "on", not "true". Else, it is always null.

Hope it helps somebody!

How do I check how many options there are in a dropdown menu?

$('#idofdropdown option').length;

That should do it.

How can I switch my signed in user in Visual Studio 2013?

There is a comment about this under this answer, but I think it's important to list it here. If you want to preserve your settings, export them first because they will be lost.

From MSDN forums - since I had to hunt around far too much to find the solution to this:

  1. Close Visual Studio
  2. Start the Developer Command prompt installed with Visual Studio as an administrator.
  3. type 'devenv /resetuserdata' ('wdexpress /resetuserdata' for Express SKUs)
  4. Start Visual Studio Normally.

Worked for me.

How to import cv2 in python3?

There is a problem with pylint, which I do not completely understood yet.

You can just import OpenCV with: from cv2 import cv2

enter image description here

Go install fails with error: no install location for directory xxx outside GOPATH

When you provide no arguments to go install, it defaults to attempting to install the package in the current directory. The error message is telling you that it cannot do that, because the current directory isn't part of your $GOPATH.

You can either:

  • Define $GOPATH to your $HOME (export GOPATH=$HOME).
  • Move your source to within the current $GOPATH (mv ~/src/go-statsd-client /User/me/gopath).

After either, going into the go-statsd-client directory and typing go install will work, and so will typing go install go-statsd-client from anywhere in the filesystem. The built binaries will go into $GOPATH/bin.

As an unrelated suggestion, you probably want to namespace your package with a domain name, to avoid name clashing (e.g., if that's where you hold your source code).

Spring MVC + JSON = 406 Not Acceptable

As it is the top answer for this error, I am adding the case for XML here.

There is also a possibility that the object returned hasn't correctly defined XML structure. That was the case for me.

public @ResponseBody DataObject getData(

Was throwing the same error despite correct headers. The errors stopped when I added @XmlRootElement to the header of the object:

public class DataObject {
    @XmlElement(name = "field", nillable = true)
    protected String field;

Java Webservice Client (Best way)

Some ideas in the following answer:

Steps in creating a web service using Axis2 - The client code

Gives an example of a Groovy client invoking the ADB classes generated from the WSDL.

There are lots of web service frameworks out there...

Where is Java's Array indexOf?

There are a couple of ways to accomplish this using the Arrays utility class.

If the array is not sorted and is not an array of primitives:


If the array is primitives and not sorted, one should use a solution offered by one of the other answers such as Kerem Baydogan's, Andrew McKinlay's or Mishax's. The above code will compile even if theArray is primitive (possibly emitting a warning) but you'll get totally incorrect results nonetheless.

If the array is sorted, you can make use of a binary search for performance:

java.util.Arrays.binarySearch(theArray, o)

In SQL Server, what does "SET ANSI_NULLS ON" mean?

I guess the main thing here is:

Never user:

  • @anything = NULL
  • @anything <> NULL
  • @anything != null

Always use:

  • @anything IS NULL
  • @anything IS NOT NULL

In Python, what does dict.pop(a,b) mean?

The pop method of dicts (like, i.e. {'a':'aaa','b':'bbb','c':'ccc'}, here) takes two arguments -- see the docs

The second argument, default, is what pop returns if the first argument, key, is absent. (If you call pop with just one argument, key, it raises an exception if that key's absent).

In your example, print b.pop('a',{'b':'bbb'}), this is irrelevant because 'a' is a key in But if you repeat that line...:

print b.pop('a',{'b':'bbb'})
print b.pop('a',{'b':'bbb'})

you'll see it makes a difference: the first pop removes the 'a' key, so in the second pop the default argument is actually returned (since 'a' is now absent from

Parsing domain from a URL

The code that was meant to work 100% didn't seem to cut it for me, I did patch the example a little but found code that wasn't helping and problems with it. so I changed it out to a couple of functions (to save asking for the list from Mozilla all the time, and removing the cache system). This has been tested against a set of 1000 URLs and seemed to work.

function domain($url)
    global $subtlds;
    $slds = "";
    $url = strtolower($url);

    $host = parse_url('http://'.$url,PHP_URL_HOST);

    preg_match("/[^\.\/]+\.[^\.\/]+$/", $host, $matches);
    foreach($subtlds as $sub){
        if (preg_match('/\.'.preg_quote($sub).'$/', $host, $xyz)){
            preg_match("/[^\.\/]+\.[^\.\/]+\.[^\.\/]+$/", $host, $matches);

    return @$matches[0];

function get_tlds() {
    $address = '';
    $content = file($address);
    foreach ($content as $num => $line) {
        $line = trim($line);
        if($line == '') continue;
        if(@substr($line[0], 0, 2) == '/') continue;
        $line = @preg_replace("/[^a-zA-Z0-9\.]/", '', $line);
        if($line == '') continue;  //$line = '.'.$line;
        if(@$line[0] == '.') $line = substr($line, 1);
        if(!strstr($line, '.')) continue;
        $subtlds[] = $line;
        //echo "{$num}: '{$line}'"; echo "<br>";

    $subtlds = array_merge(array(
            '', '', '', '', '', '', 
            '', '', '', '', '', '',
            '', '', '', '', '', ''
        ), $subtlds);

    $subtlds = array_unique($subtlds);

    return $subtlds;    

Then use it like

$subtlds = get_tlds();
echo domain('') //outputs:
echo domain('') //outputs:
echo domain('') //outputs:

I know I should have turned this into a class, but didn't have time.

How can I solve ORA-00911: invalid character error?

I'm using a 3rd party program that executes Oracle SQL and I encountered this error. Prior to a SELECT statement, I had some commented notes that included special characters. Removing the comments resolved the issue.

How do you clear a slice in Go?

It all depends on what is your definition of 'clear'. One of the valid ones certainly is:

slice = slice[:0]

But there's a catch. If slice elements are of type T:

var slice []T

then enforcing len(slice) to be zero, by the above "trick", doesn't make any element of


eligible for garbage collection. This might be the optimal approach in some scenarios. But it might also be a cause of "memory leaks" - memory not used, but potentially reachable (after re-slicing of 'slice') and thus not garbage "collectable".

What is the difference between SessionState and ViewState?

Session state is saved on the server, ViewState is saved in the page.

Session state is usually cleared after a period of inactivity from the user (no request happened containing the session id in the request cookies).

The view state is posted on subsequent post back in a hidden field.

Backporting Python 3 open(encoding="utf-8") to Python 2

Here's one way:

with open("filename.txt", "rb") as f:
    contents ="UTF-8")

max value of integer

The strict equivalent of the java int is long int in C.

Edit: If int32_t is defined, then it is the equivalent in terms of precision. long int guarantee the precision of the java int, because it is guarantee to be at least 32 bits in size.

Is it possible to install another version of Python to Virtualenv?

The usual approach is to download the source and build and install locally (but not directly in virtualenv), and then create a new virtualenv using that local Python install. On some systems, it may be possible to download and install a prebuilt python, rather than building from source.

Is there a simple way to increment a datetime object one month in Python?

Note: This answer shows how to achieve this using only the datetime and calendar standard library (stdlib) modules - which is what was explicitly asked for. The accepted answer shows how to better achieve this with one of the many dedicated non-stdlib libraries. If you can use non-stdlib libraries, by all means do so for these kinds of date/time manipulations!

How about this?

def add_one_month(orig_date):
    # advance year and month by one month
    new_year = orig_date.year
    new_month = orig_date.month + 1
    # note: in, months go from 1 to 12
    if new_month > 12:
        new_year += 1
        new_month -= 12

    new_day =
    # while day is out of range for month, reduce by one
    while True:
            new_date =, new_month, new_day)
        except ValueError as e:
            new_day -= 1

    return new_date


Improved version which:

  1. keeps the time information if given a datetime.datetime object
  2. doesn't use try/catch, instead using calendar.monthrange from the calendar module in the stdlib:
import datetime
import calendar

def add_one_month(orig_date):
    # advance year and month by one month
    new_year = orig_date.year
    new_month = orig_date.month + 1
    # note: in, months go from 1 to 12
    if new_month > 12:
        new_year += 1
        new_month -= 12

    last_day_of_month = calendar.monthrange(new_year, new_month)[1]
    new_day = min(, last_day_of_month)

    return orig_date.replace(year=new_year, month=new_month, day=new_day)

C++ equivalent of Java's toString?

The question has been answered. But I wanted to add a concrete example.

class Point{

      Point(int theX, int theY) :x(theX), y(theY)
      // Print the object
      friend ostream& operator <<(ostream& outputStream, const Point& p);
      int x;
      int y;

ostream& operator <<(ostream& outputStream, const Point& p){
       int posX = p.x;
       int posY = p.y;

       outputStream << "x="<<posX<<","<<"y="<<posY;
      return outputStream;

This example requires understanding operator overload.

How to return a value from try, catch, and finally?

It is because you are in a try statement. Since there could be an error, sum might not get initialized, so put your return statement in the finally block, that way it will for sure be returned.

Make sure that you initialize sum outside the try/catch/finally so that it is in scope.

How to pass in password to pg_dump?

As detailed in this blog post , there are two ways to non interactively provide a password to PostgreSQL utilities such as the "pg_dump" command: using the ".pgpass" file or using the "PGPASSWORD" environment variable.

Is there a foreach loop in Go?

Yes, Range :

The range form of the for loop iterates over a slice or map.

When ranging over a slice, two values are returned for each iteration. The first is the index, and the second is a copy of the element at that index.

Example :

package main

import "fmt"

var pow = []int{1, 2, 4, 8, 16, 32, 64, 128}

func main() {
    for i, v := range pow {
        fmt.Printf("2**%d = %d\n", i, v)

    for i := range pow {
        pow[i] = 1 << uint(i) // == 2**i
    for _, value := range pow {
        fmt.Printf("%d\n", value)
  • You can skip the index or value by assigning to _.
  • If you only want the index, drop the , value entirely.

jquery simple image slideshow tutorial

This is by far the easiest example I have found on the net.

Summaring the example, this is what you need to do a slideshow:


<div id="slideshow">
    <img src="img1.jpg" style="position:absolute;" class="active" />
    <img src="img2.jpg" style="position:absolute;" />
    <img src="img3.jpg" style="position:absolute;" />

Position absolute is used to put an each image over the other.


<style type="text/css">

The image that has the class="active" will appear over the others, the class=active property will change with the following Jquery code.

    function slideSwitch() {
        var $active = $('div#slideshow');
        var $next = $;    



    $(function() {
        setInterval( "slideSwitch()", 5000 );

If you want to go further with slideshows I suggest you to have a look at the link above (to see animated oppacity changes - 2n example) or at other more complex slideshows tutorials.

Set UITableView content inset permanently

            .flatMapLatest { _ in RxKeyboard.instance.isHidden }
            .bind(onNext: { [unowned self] isHidden in
                guard !isHidden else { return }
                self.tableView.contentInsetAdjustmentBehavior = .automatic
            .disposed(by: self.disposeBag)

Creating a left-arrow button (like UINavigationBar's "back" style) on a UIToolbar

enter image description here

First of all you have to find an image of the back button. I used a nice app called Extractor that extracts all the graphics from iPhone. In iOS7 I managed to retrieve the image called UINavigationBarBackIndicatorDefault and it was in black colour, since I needed a red tint I change the colour to red using Gimp.


As was mentioned by btate in his comment, there is no need to change the color with the image editor. The following code should do the trick:

imageView.tint = [UIColor redColor];
imageView.image = [[UIImage imageNamed:@"UINavigationBarBackIndicatorDefault"] imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];

Then I created a view that contains an imageView with that arrow, a label with the custom text and on top of the view I have a button with an action. Then I added a simple animation (fading and translation).

The following code simulates the behaviour of the back button including animation.

        UIImageView *imageView=[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"UINavigationBarBackIndicatorDefault"]];
        [imageView setTintColor:[UIColor redColor]];
        UILabel *label=[[UILabel alloc] init];
        [label setTextColor:[UIColor redColor]];
        [label setText:@"Blog"];
        [label sizeToFit];

        int space=6;
        label.frame=CGRectMake(imageView.frame.origin.x+imageView.frame.size.width+space, label.frame.origin.y, label.frame.size.width, label.frame.size.height);
        UIView *view=[[UIView alloc] initWithFrame:CGRectMake(0, 0, label.frame.size.width+imageView.frame.size.width+space, imageView.frame.size.height)];

        view.bounds=CGRectMake(view.bounds.origin.x+8, view.bounds.origin.y-1, view.bounds.size.width, view.bounds.size.height);
        [view addSubview:imageView];
        [view addSubview:label];

        UIButton *button=[[UIButton alloc] initWithFrame:view.frame];
        [button addTarget:self action:@selector(handleBack:) forControlEvents:UIControlEventTouchUpInside];
        [view addSubview:button];

        [UIView animateWithDuration:0.33 delay:0 options:UIViewAnimationOptionCurveLinear animations:^{
            label.alpha = 0.0;
            CGRect orig=label.frame;
            label.frame=CGRectMake(label.frame.origin.x+25, label.frame.origin.y, label.frame.size.width, label.frame.size.height);
            label.alpha = 1.0;
        } completion:nil];

        UIBarButtonItem *backButton =[[UIBarButtonItem alloc] initWithCustomView:view];

- (void) handleBack:(id)sender{


Instead of adding the button, in my opinion the better approach is to use a gesture recognizer.

UITapGestureRecognizer* tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleBack:)];
[view addGestureRecognizer:tap];
[view setUserInteractionEnabled:YES];

How to run test cases in a specified file?

in intelliJ IDEA go-lang plugin (and i assume in jetbrains Gogland) you can just set the test kind to file under run > edit configurations

screenshot create go test on go file

How to catch and print the full exception traceback without halting/exiting the program?

python 3 solution

from linecache import getline
import sys
import traceback

def get_stack_trace():
    exc_type, exc_value, exc_tb = sys.exc_info()
    trace = traceback.format_stack()
    trace = list(filter(lambda x: ("\\lib\\" not in x and "/lib/" not in x and "" not in x), trace))
    ex_type = exc_type.__name__
    ex_line = exc_tb.tb_lineno
    ex_file = exc_tb.tb_frame.f_code.co_filename
    ex_message = str(exc_value)
    line_code = ""
        line_code = getline(ex_file, ex_line).strip()

        0, f'File "{ex_file}", line {ex_line}, line_code: {line_code} , ex: {ex_type} {ex_message}',
    return trace

def get_stack_trace_str(msg: str = ""):
    trace = list(get_stack_trace())
    trace_str = "\n".join(list(map(str, trace)))
    trace_str = msg + "\n" + trace_str
    return trace_str

How to move up a directory with Terminal in OS X

To move up a directory, the quickest way would be to add an alias to ~/.bash_profile

alias ..='cd ..'

and then one would need only to type '..[return]'.

Returning a value from thread?

One of the easiest ways to get a return value from a thread is to use closures. Create a variable that will hold the return value from the thread and then capture it in a lambda expression. Assign the "return" value to this variable from the worker thread and then once that thread ends you can use it from the parent thread.

void Main()
  object value = null; // Used to store the return value
  var thread = new Thread(
    () =>
      value = "Hello World"; // Publish the return value
  Console.WriteLine(value); // Use the return value here

Assign variable value inside if-statement

an assignment returns the left-hand side of the assignment. so: yes. it is possible. however, you need to declare the variable outside:

int v = 1;
if((v = someMethod()) != 0) {

py2exe - generate single executable file

As the other poster mention, py2exe, will generate an executable + some libraries to load. You can also have some data to add to your program.

Next step is to use an installer, to package all this into one easy-to-use installable/unistallable program.

I have used InnoSetup with delight for several years and for commercial programs, so I heartily recommend it.

Install dependencies globally and locally using package.json

Due to the disadvantages described below, I would recommend following the accepted answer:

Use npm install --save-dev [package_name] then execute scripts with:

$ npm run lint
$ npm run build
$ npm test

My original but not recommended answer follows.

Instead of using a global install, you could add the package to your devDependencies (--save-dev) and then run the binary from anywhere inside your project:

"$(npm bin)/<executable_name>" <arguments>...

In your case:

"$(npm bin)"/ --help

This engineer provided an npm-exec alias as a shortcut. This engineer uses a shellscript called But I prefer to use $(npm bin) directly, to avoid any extra file or setup.

Although it makes each call a little larger, it should just work, preventing:

  • potential dependency conflicts with global packages (@nalply)
  • the need for sudo
  • the need to set up an npm prefix (although I recommend using one anyway)


  • $(npm bin) won't work on Windows.
  • Tools deeper in your dev tree will not appear in the npm bin folder. (Install npm-run or npm-which to find them.)

It seems a better solution is to place common tasks (such as building and minifying) in the "scripts" section of your package.json, as Jason demonstrates above.

Java: how to represent graphs?

Time ago I had the same problem and did my own implementation. What I suggest you is to implement another class: Edge. Then, a Vertex will have a List of Edge.

public class Edge {
    private Node a, b;
    private directionEnum direction;     // AB, BA or both
    private int weight;

It worked for me. But maybe is so simple. There is this library that maybe can help you if you look into its code:

Should C# or C++ be chosen for learning Games Programming (consoles)?

If you want to be employed professionally as a game developer you need to know C/C++. End of story!

Convert a tensor to numpy array in Tensorflow?

I was searching for days for this command.

This worked for me outside any session or somthing like this.

# you get an array = your tensor.eval(session=tf.compat.v1.Session())
an_array = a_tensor.eval(session=tf.compat.v1.Session())

Ruby: character to ascii from a string

You could also just call to_a after each_byte or even better String#bytes

=> 'hello world'.each_byte.to_a
=> [104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]

=> 'hello world'.bytes
=> [104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]

Inner join with count() on three tables

One needs to understand what a JOIN or a series of JOINs does to a set of data. With strae's post, a pe_id of 1 joined with corresponding order and items on pe_id = 1 will give you the following data to "select" from:

[ table people portion ] [ table orders portion ] [ table items portion ]

| people.pe_id | people.pe_name | orders.ord_id | orders.pe_id | orders.ord_title | item.item_id | item.ord_id | item.pe_id | item.title |

| 1 | Foo | 1 | 1 | First order | 1 | 1 | 1 | Apple |
| 1 | Foo | 1 | 1 | First order | 2 | 1 | 1 | Pear |

The joins essentially come up with a cartesian product of all the tables. You basically have that data set to select from and that's why you need a distinct count on orders.ord_id and items.item_id. Otherwise both counts will result in 2 - because you effectively have 2 rows to select from.

How to retrieve a recursive directory and file list from PowerShell excluding some files and folders?

A bit late, but try this one.

function Set-Files($Path) {
    if(Test-Path $Path -PathType Leaf) {
        # Do any logic on file
        Write-Host $Path

    if(Test-Path $path -PathType Container) {
        # Do any logic on folder use exclude on get-childitem
        # cycle again
        Get-ChildItem -Path $path | foreach { Set-Files -Path $_.FullName }

# call
Set-Files -Path 'D:\myFolder'

IntelliJ IDEA 13 uses Java 1.5 despite setting to 1.7

Please check your project/module language levels (Project Structure | Project; Project Structure | Modules | module-name | Sources). You might also want to take a look at Settings | Compiler | Java Compiler | Per-module bytecode version.

Set also this:

File -> Project Structure -> Modules :: Sources (next to Paths and Dependencies) and that has a "Language level" option which also needs to be set correctly.

How to create an executable .exe file from a .m file

I developed a non-matlab software for direct compilation of m-files (TMC Compiler). This is an open-source converter of m-files projects to C. The compiler produces the C code that may be linked with provided open-source run-time library to produce a stand-alone application. The library implements a set of build-in functions; the linear-algebra operations use LAPACK code. It is possible to expand the set of the build-in functions by custom implementation as described in the documentation.

Does Android support near real time push notification?

Firebase Cloud Messaging FCM FAQ is the new version of GCM. It inherits GCM’s core infrastructure to deliver messages reliably on Android, iOS and Chrome. However they'll continue to support GCM because lot of developers are using GCM SDKs today to handle notifications, and client app upgrade takes time.

As of June 26, 2012, Google Cloud Messaging is the preferred way of sending messages to applications running on devices.

Previously (and now deprecated), the service was called Cloud To Device Messaging.

How to convert from java.sql.Timestamp to java.util.Date?

The problem is probably coming from the fact that Date is deprecated.

Consider using




Edit 2015:

Java 8 and later has built-in the new java.time package, which is similar to Joda-Time.

MySQL dump by query

mysql Export the query results command line:

mysql -h120.26.133.63 -umiyadb -proot123 miya -e "select * from user where id=1" > mydumpfile.txt

Convert decimal to hexadecimal in UNIX shell script

xd() {
    printf "hex> "
    while read i
        printf "dec  $(( 0x${i} ))\n\nhex> "
dx() {
    printf "dec> "
    while read i
        printf 'hex  %x\n\ndec> ' $i

What is the difference between pip and conda?

Quoting from the Conda blog:

Having been involved in the python world for so long, we are all aware of pip, easy_install, and virtualenv, but these tools did not meet all of our specific requirements. The main problem is that they are focused around Python, neglecting non-Python library dependencies, such as HDF5, MKL, LLVM, etc., which do not have a in their source code and also do not install files into Python’s site-packages directory.

So Conda is a packaging tool and installer that aims to do more than what pip does; handle library dependencies outside of the Python packages as well as the Python packages themselves. Conda also creates a virtual environment, like virtualenv does.

As such, Conda should be compared to Buildout perhaps, another tool that lets you handle both Python and non-Python installation tasks.

Because Conda introduces a new packaging format, you cannot use pip and Conda interchangeably; pip cannot install the Conda package format. You can use the two tools side by side (by installing pip with conda install pip) but they do not interoperate either.

Since writing this answer, Anaconda has published a new page on Understanding Conda and Pip, which echoes this as well:

This highlights a key difference between conda and pip. Pip installs Python packages whereas conda installs packages which may contain software written in any language. For example, before using pip, a Python interpreter must be installed via a system package manager or by downloading and running an installer. Conda on the other hand can install Python packages as well as the Python interpreter directly.

and further on

Occasionally a package is needed which is not available as a conda package but is available on PyPI and can be installed with pip. In these cases, it makes sense to try to use both conda and pip.

RuntimeError on windows trying python multiprocessing

On Windows the subprocesses will import (i.e. execute) the main module at start. You need to insert an if __name__ == '__main__': guard in the main module to avoid creating subprocesses recursively.


import parallelTestModule

if __name__ == '__main__':    
    extractor = parallelTestModule.ParallelExtractor()
    extractor.runInParallel(numProcesses=2, numThreads=4)

Wireshark vs Firebug vs Fiddler - pros and cons?

None of the above, if you are on a Mac. Use Charles Proxy. It's the best network/request information collecter that I have ever come across. You can view and edit all outgoing requests, and see the responses from those requests in several forms, depending on the type of the response. It costs 50 dollars for a license, but you can download the trial version and see what you think.

If your on Windows, then I would just stay with Fiddler.

Android studio takes too much memory

I have used all of Sam's recommendations above, but I found that the VM command line options are no longer supported as described. (I received an error when used)

As an alternative, I was able to reduce gradle dramatically by adding the following line to the "" file

org.gradle.jvmargs=-Xms512m -Xmx1024m

As of A.S. ver 1.3, the file is located in the same folder level as "".

The above configuration is a "memory stack" of 512 meg, and "memory heap" of 1024 meg.

I tested this on a small project, using settings where both memory sizes were set to 256 meg. It limited the JVM sizes as expected. In all my tests, I restarted A.S. to force the JVM to restart.

Hopefully, this will save others dealing with this issue from getting those "Get yourself a better computer" responses. :-)


Change the Blank Cells to "NA"

I suspect everyone has an answer already, though in case someone comes looking, dplyr na_if() would be (from my perspective) the more efficient of those mentioned:

# Import CSV, convert all 'blank' cells to NA
dat <- read.csv("data2.csv") %>% na_if("")

Here is an additional approach leveraging readr's read_delim function. I just picked-up (probably widely know, but I'll archive here for future users). This is very straight forward and more versatile than the above, as you can capture all types of blank and NA related values in your csv file:

dat <- read_csv("data2.csv", na = c("", "NA", "N/A"))

Note the underscore in readr's version versus Base R "." in read_csv.

Hopefully this helps someone who wanders upon the post!

Reading data from DataGridView in C#

something like

for (int rows = 0; rows < dataGrid.Rows.Count; rows++)
     for (int col= 0; col < dataGrid.Rows[rows].Cells.Count; col++)
        string value = dataGrid.Rows[rows].Cells[col].Value.ToString();


example without using index

foreach (DataGridViewRow row in dataGrid.Rows)
    foreach (DataGridViewCell cell in row.Cells)
        string value = cell.Value.ToString();


how to emulate "insert ignore" and "on duplicate key update" (sql merge) with postgresql?

Try to do an UPDATE. If it doesn't modify any row that means it didn't exist, so do an insert. Obviously, you do this inside a transaction.

You can of course wrap this in a function if you don't want to put the extra code on the client side. You also need a loop for the very rare race condition in that thinking.

There's an example of this in the documentation:, example 40-2 right at the bottom.

That's usually the easiest way. You can do some magic with rules, but it's likely going to be a lot messier. I'd recommend the wrap-in-function approach over that any day.

This works for single row, or few row, values. If you're dealing with large amounts of rows for example from a subquery, you're best of splitting it into two queries, one for INSERT and one for UPDATE (as an appropriate join/subselect of course - no need to write your main filter twice)

Determine what attributes were changed in Rails after_save callback?

For those who want to know the changes just made in an after_save callback:

Rails 5.1 and greater


Rails < 5.1


Also see:

mysqli_real_connect(): (HY000/2002): No such file or directory

mysqli_connect(): (HY000/2002): No such file or directory


I was just wanted to run some PHPUnit tests on my Mac, using Terminal. Some of the classes I wanna test was having to connect MySQL DB which was created and managed by PHPMyAdmin, and the web app I was working was working fine in the localhost. So when I ran that testcases I got the following error on my terminal:

mysqli_connect(): (HY000/2002): No such file or directory


So with the itchiness I had to resolve it and run my test I searched in few SO Q&A threads and tried out. And a combination of changes worked for me.

  1. Locate your file which relates to PHPMyAdmin.
  2. Locate the line $cfg['Servers'][$i]['host'] mostly this line might have been commented out by default, if so please uncomment it.
  3. And replace that line with following:

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

  1. Save it and restart the MySQL Database from your XAMPP control panel (manager-osx).
  2. Change your $host parameter value in the mysqli_connect() method to following:

$_connection = mysqli_connect(**"localhost: 3306"**, $_mysql_username, $_mysql_password, $_database);

Note: This 3306 is my MySQL port number which is its default. You should better check what's your actual MySQL Port number before going to follow these steps.

And that's all. For me only these set of steps worked and nothing else. I ran my Unit Tests and it's working fine and the DB data were also updated properly according to the tests.

Why this works:

The closest reason I could have found is that it works because sometimes the mysqli_connect method requires a working socket(IP Address of the DB Host along with the Port number) of the database. So if you have commented out the $cfg['Servers'][$i]['host'] = ''; line or have set 'localhost' as the value in it, it ignores the port number. But if you wanna use a socket, then you have to use '' or the real hostname. (for me it appears to be regardless of the default port number we really have, we have to do the above steps.) Read the following link of PHPMyAdmin for further details.

Hope this might be helpful to somebody else out there.


Best database field type for a URL

You should use a VARCHAR with an ASCII character encoding. URLs are percent encoded and international domain names use punycode so ASCII is enough to store them. This will use much less space than UTF8.

VARCHAR(512) CHARACTER SET 'ascii' COLLATE 'ascii_general_ci' NOT NULL

What are the differences and similarities between ffmpeg, libav, and avconv?

Confusing messages

These messages are rather misleading and understandably a source of confusion. Older Ubuntu versions used Libav which is a fork of the FFmpeg project. FFmpeg returned in Ubuntu 15.04 "Vivid Vervet".

The fork was basically a non-amicable result of conflicting personalities and development styles within the FFmpeg community. It is worth noting that the maintainer for Debian/Ubuntu switched from FFmpeg to Libav on his own accord due to being involved with the Libav fork.

The real ffmpeg vs the fake one

For a while both Libav and FFmpeg separately developed their own version of ffmpeg.

Libav then renamed their bizarro ffmpeg to avconv to distance themselves from the FFmpeg project. During the transition period the "not developed anymore" message was displayed to tell users to start using avconv instead of their counterfeit version of ffmpeg. This confused users into thinking that FFmpeg (the project) is dead, which is not true. A bad choice of words, but I can't imagine Libav not expecting such a response by general users.

This message was removed upstream when the fake "ffmpeg" was finally removed from the Libav source, but, depending on your version, it can still show up in Ubuntu because the Libav source Ubuntu uses is from the ffmpeg-to-avconv transition period.

In June 2012, the message was re-worded for the package libav - 4:0.8.3-0ubuntu0.12.04.1. Unfortunately the new "deprecated" message has caused additional user confusion.

Starting with Ubuntu 15.04 "Vivid Vervet", FFmpeg's ffmpeg is back in the repositories again.

libav vs Libav

To further complicate matters, Libav chose a name that was historically used by FFmpeg to refer to its libraries (libavcodec, libavformat, etc). For example the libav-user mailing list, for questions and discussions about using the FFmpeg libraries, is unrelated to the Libav project.

How to tell the difference

If you are using avconv then you are using Libav. If you are using ffmpeg you could be using FFmpeg or Libav. Refer to the first line in the console output to tell the difference: the copyright notice will either mention FFmpeg or Libav.

Secondly, the version numbering schemes differ. Each of the FFmpeg or Libav libraries contains a version.h header which shows a version number. FFmpeg will end in three digits, such as 57.67.100, and Libav will end in one digit such as 57.67.0. You can also view the library version numbers by running ffmpeg or avconv and viewing the console output.

If you want to use the real ffmpeg

Ubuntu 15.04 "Vivid Vervet" or newer

The real ffmpeg is in the repository, so you can install it with:

apt-get install ffmpeg

For older Ubuntu versions

Your options are:

These methods are non-intrusive, reversible, and will not interfere with the system or any repository packages.

Another possible option is to upgrade to Ubuntu 15.04 "Vivid Vervet" or newer and just use ffmpeg from the repository.

Also see

For an interesting blog article on the situation, as well as a discussion about the main technical differences between the projects, see The FFmpeg/Libav situation.

How can I use Oracle SQL developer to run stored procedures?

Not only is there a way to do this, there is more than one way to do this (which I concede is not very Pythonic, but then SQL*Developer is written in Java ).

I have a procedure with this signature: get_maxsal_by_dept( dno number, maxsal out number).

I highlight it in the SQL*Developer Object Navigator, invoke the right-click menu and chose Run. (I could use ctrl+F11.) This spawns a pop-up window with a test harness. (Note: If the stored procedure lives in a package, you'll need to right-click the package, not the icon below the package containing the procedure's name; you will then select the sproc from the package's "Target" list when the test harness appears.) In this example, the test harness will display the following:

  DNO := NULL;

    DNO => DNO,

I set the variable DNO to 50 and press okay. In the Running - Log pane (bottom right-hand corner unless you've closed/moved/hidden it) I can see the following output:

Connecting to the database apc.
MAXSAL = 4500
Process exited.
Disconnecting from the database apc. 

To be fair the runner is less friendly for functions which return a Ref Cursor, like this one: get_emps_by_dept (dno number) return sys_refcursor.

  v_Return sys_refcursor;
  DNO := 50;

  v_Return := GET_EMPS_BY_DEPT(
    DNO => DNO
  -- Modify the code to output the variable
  -- DBMS_OUTPUT.PUT_LINE('v_Return = ' || v_Return);

However, at least it offers the chance to save any changes to file, so we can retain our investment in tweaking the harness...

  v_Return sys_refcursor;
  v_rec emp%rowtype;
  DNO := 50;

  v_Return := GET_EMPS_BY_DEPT(
    DNO => DNO

    fetch v_Return into v_rec;
    exit when v_Return%notfound;
    DBMS_OUTPUT.PUT_LINE('name = ' || v_rec.ename);
  end loop;

The output from the same location:

Connecting to the database apc.
name = PODER
Process exited.
Disconnecting from the database apc. 

Alternatively we can use the old SQLPLus commands in the SQLDeveloper worksheet:

var rc refcursor 
exec :rc := get_emps_by_dept(30) 
print rc

In that case the output appears in Script Output pane (default location is the tab to the right of the Results tab).

The very earliest versions of the IDE did not support much in the way of SQL*Plus. However, all of the above commands have been supported since 1.2.1. Refer to the matrix in the online documentation for more info.

"When I type just var rc refcursor; and select it and run it, I get this error (GUI):"

There is a feature - or a bug - in the way the worksheet interprets SQLPlus commands. It presumes SQLPlus commands are part of a script. So, if we enter a line of SQL*Plus, say var rc refcursor and click Execute Statement (or F9 ) the worksheet hurls ORA-900 because that is not an executable statement i.e. it's not SQL . What we need to do is click Run Script (or F5 ), even for a single line of SQL*Plus.

"I am so close ... please help."

You program is a procedure with a signature of five mandatory parameters. You are getting an error because you are calling it as a function, and with just the one parameter:

exec :rc := get_account(1)

What you need is something like the following. I have used the named notation for clarity.

var ret1 number
var tran_cnt number
var msg_cnt number
var rc refcursor

exec :tran_cnt := 0
exec :msg_cnt := 123

exec get_account (Vret_val => :ret1, 
                  Vtran_count => :tran_cnt, 
                  Vmessage_count => :msg_cnt, 
                  Vaccount_id   => 1,
                  rc1 => :rc )

print tran_count 
print rc

That is, you need a variable for each OUT or IN OUT parameter. IN parameters can be passed as literals. The first two EXEC statements assign values to a couple of the IN OUT parameters. The third EXEC calls the procedure. Procedures don't return a value (unlike functions) so we don't use an assignment syntax. Lastly this script displays the value of a couple of the variables mapped to OUT parameters.

Convert Long into Integer

long visitors =1000;

int convVisitors =(int)visitors;

How to compile LEX/YACC files on Windows?

As for today (2011-04-05, updated 2017-11-29) you will need the lastest versions of:

  1. flex-2.5.4a-1.exe

  2. bison-2.4.1-setup.exe

  3. After that, do a full install in a directory of your preference without spaces in the name. I suggest C:\GnuWin32. Do not install it in the default (C:\Program Files (x86)\GnuWin32) because bison has problems with spaces in directory names, not to say parenthesis.

  4. Also, consider installing Dev-CPP in the default directory (C:\Dev-Cpp)

  5. After that, set the PATH variable to include the bin directories of gcc (in C:\Dev-Cpp\bin) and flex\bison (in C:\GnuWin32\bin). To do that, copy this: ;C:\Dev-Cpp\bin;C:\GnuWin32\bin and append it to the end of the PATH variable, defined in the place show by this figure:
    step-by-step to set PATH variable under Win-7.
    If the figure is not in good resolution, you can see a step-by-step here.

  6. Open a prompt, cd to the directory where your ".l" and ".y" are, and compile them with:

    1. flex hello.l
    2. bison -dy hello.y
    3. gcc lex.yy.c -o hello.exe

Commands to create lexical analyzer, parser and executable.

You will be able to run the program. I made the sources for a simple test (the infamous Hello World):



#include ""
int yyerror(char *errormsg);



("hi"|"oi")"\n"       { return HI;  }
("tchau"|"bye")"\n"   { return BYE; }
.                     { yyerror("Unknown char");  }


int main(void)
   return 0;

int yywrap(void)
   return 0;

int yyerror(char *errormsg)
    fprintf(stderr, "%s\n", errormsg);



#include <stdio.h>
#include <stdlib.h>
int yylex(void);
int yyerror(const char *s);


%token HI BYE


         hi bye

        HI     { printf("Hello World\n");   }
        BYE    { printf("Bye World\n"); exit(0); }

Edited: avoiding "warning: implicit definition of yyerror and yylex".

Disclaimer: remember, this answer is very old (since 2011!) and if you run into problems due to versions and features changing, you might need more research, because I can't update this answer to reflect new itens. Thanks and I hope this will be a good entry point for you as it was for many.

Updates: if something (really small changes) needs to be done, please check out the official repository at github:

Happy hacking.

Make ABC Ordered List Items Have Bold Style

a bit of a cheat, but it works:


<ol type="A" style="font-weight: bold;">
  <li><span>More text</span></li>


li span { font-weight: normal; }

Android Facebook style slide

I'm going to make some bold guesses here...

I assume they have a layout that represents the menu that is not visible. When the menu button is tapped, they animate the layout/view on top to move out of the way, and simply enable the visibility of the menu layout. I have not thought about this causing any sort of z-index issues in the views, or how they control that.

Trying to get PyCharm to work, keep getting "No Python interpreter selected"

Even I got the same issue and my mistake was that I didn't download python MSI file. You will get it here:

Once you download the msi, run the setup and that will solve the problem. After that you can go to File->Settings->Project Settings->Project Interpreter->Python Interpreters

and select the python.exe file. (This file will be available at c:\Python34) Select the python.exe file. That's it.

Sending SMS from PHP

PHP by itself has no SMS module or functions and doesn't allow you to send SMS.

SMS ( Short Messaging System) is a GSM technology an you need a GSM provider that will provide this service for you and may have an PHP API implementation for it.

Usually people in telecom business use Asterisk to handle calls and sms programming.

How to disable RecyclerView scrolling?

Override onTouchEvent() and onInterceptTouchEvent() and return false if you don't need OnItemTouchListener at all. This does not disable OnClickListeners of ViewHolders.

public class ScrollDisabledRecyclerView extends RecyclerView {
    public ScrollDisabledRecyclerView(Context context) {

    public ScrollDisabledRecyclerView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);

    public ScrollDisabledRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    public boolean onTouchEvent(MotionEvent e) {
        return false;

    public boolean onInterceptTouchEvent(MotionEvent e) {
        return false;

DateTime.ToString() format that can be used in a filename or extension?

You can use this:


Reload a DIV without reloading the whole page

Your html is not updated every 15 seconds. The cause could be browser caching. Add Math.random() to avoid browser caching, and it's better to wait until the DOM is fully loaded as pointed out by @shadow. But I think the main cause is the caching

<script type="text/javascript" src="" />
<script type="text/javascript">
    var auto_refresh = setInterval(
    function ()
       $('.View').load('Small.php?' + Math.random()).fadeIn("slow");
    }, 15000); // refresh every 15000 milliseconds

chrome : how to turn off user agent stylesheet settings?

  1. Open Chrome dev tools
  2. Click gear icon on bottom right
  3. In General section, check or uncheck "Show user agent styles".

Android Studio: Can't start Git

In my case, with GitHub Desktop for Windows (as of June 2, 2016) & Android Studio 2.1:

This folder ->


Contained a BATCH file called something like 'post-install.bat'. Run this file to create a folder 'cmd' with 'git.exe' inside.

This path-->


would be the location of 'git.exe' after running the post-install script.

Easiest way to mask characters in HTML(5) text input

A little late, but a useful plugin that will actually use a mask to give a bit more restriction on user input.

<div class="col-sm-3 col-md-6 col-lg-4">
  <div class="form-group">
     <label for="addPhone">Phone Number *</label>
      <input id="addPhone" name="addPhone" type="text" class="form-control 
       required" data-mask="(999) 999-9999"placeholder>
    <span class="help-block">(999) 999-9999</span>

 <!-- Input Mask -->
 <script src="js/plugins/jasny/jasny-bootstrap.min.js"></script>

enter image description here

More info on the plugin

How to get the Enum Index value in C#

Firstly, there could be two values that you're referring to:

Underlying Value

If you are asking about the underlying value, which could be any of these types: byte, sbyte, short, ushort, int, uint, long or ulong

Then you can simply cast it to it's underlying type. Assuming it's an int, you can do it like this:

int eValue = (int)enumValue;

However, also be aware of each items default value (first item is 0, second is 1 and so on) and the fact that each item could have been assigned a new value, which may not necessarily be in any order particular order! (Credit to @JohnStock for the poke to clarify).

This example assigns each a new value, and show the value returned:

public enum MyEnum
    MyValue1 = 34,
    MyValue2 = 27

(int)MyEnum.MyValue2 == 27; // True

Index Value

The above is generally the most commonly required value, and is what your question detail suggests you need, however each value also has an index value (which you refer to in the title). If you require this then please see other answers below for details.

What does void mean in C, C++, and C#?

Three usage cases for void:

  1. Function signatures. void foo(int bar) does not return a value. int bar(void) does not take any parameters but this is usually expressed with empty argument list: int bar(). Usage of the void keyword here corresponds to its meaning in English.

  2. Generic top-type pointer void * that points to unspecified data and cannot be dereferenced. Here the meaning of void is different from other meanings of void: universal type vs. no type.

  3. In casts such as (void) new Foo(this) to signify that the return value is deliberately thrown away. Here the keyword usage also matches its meaning in English.

Cases 1 and 2 were already covered by @Gerald but case 3 has not been addressed yet.

How to get the id of the element clicked using jQuery

Since you are loading in the spans via ajax you will have to attach delegate handlers to the events to catch them as they bubble up.


you will want to attach the event to the closest static member you can to increase efficiency.


is better than binding to the document for instance.

This question may help you understand

Direct vs. Delegated - jQuery .on()

Efficient way to remove ALL whitespace from String?

We can use:

    public static string RemoveWhitespace(this string input)
        if (input == null)
            return null;
        return new string(input.ToCharArray()
            .Where(c => !Char.IsWhiteSpace(c))

How do I get currency exchange rates via an API such as Google Finance?

Here are some exchange APIs with PHP example.

[ Open Exchange Rates API ]

Provides 1,000 requests per month free. You must register and grab the App ID. The base currency USD for free account. Check the supported currencies and documentation.

// open exchange URL // valid app_id * REQUIRED *
$exchange_url = '';
$params = array(
    'app_id' => 'YOUR_APP_ID'

// make cURL request // parse JSON
$curl = curl_init();
curl_setopt_array($curl, array(
    CURLOPT_URL => $exchange_url . '?' . http_build_query($params),
$response = json_decode(curl_exec($curl));

if (!empty($response->rates)) {
    // convert 150 USD to JPY ( Japanese Yen )
    echo $response->rates->JPY * 150;

150 USD = 18039.09015 JPY

[ Currency Layer API ]

Provides 1,000 requests per month free. You must register and grab the Access KEY. Custom base currency is not supported in free account. Check the documentation.

$exchange_url = '';
$params = array(
    'access_key' => 'YOUR_ACCESS_KEY',
    'source' => 'USD',
    'currencies' => 'JPY',
    'format' => 1 // 1 = JSON

// make cURL request // parse JSON
$curl = curl_init();
curl_setopt_array($curl, array(
    CURLOPT_URL => $exchange_url . '?' . http_build_query($params),
$response = json_decode(curl_exec($curl));

if (!empty($response->quotes)) {
    // convert 150 USD to JPY ( Japanese Yen )
    echo '150 USD = ' . $response->quotes->USDJPY * 150 . ' JPY';

150 USD = 18036.75045 JPY

Is there a method for String conversion to Title Case?

This is something I wrote to convert snake_case to lowerCamelCase but could easily be adjusted based on the requirements

private String convertToLowerCamel(String startingText)
    String[] parts = startingText.split("_");
    return parts[0].toLowerCase() +
                    .map(part -> part.substring(0, 1).toUpperCase() + part.substring(1).toLowerCase())

Pass a PHP string to a JavaScript variable (and escape newlines)

I'm not sure if this is bad practice or no, but my team and I have been using a mixed html, JS, and php solution. We start with the PHP string we want to pull into a JS variable, lets call it:


Next we use in-page hidden form elements, and have their value set as the string:

<form id="pagePhpVars" method="post">
<input type="hidden" name="phpString1" id="phpString1" value="'.$someString.'" />

Then its a simple matter of defining a JS var through document.getElementById:

<script type="text/javascript" charset="UTF-8">
    var moonUnitAlpha = document.getElementById('phpString1').value;

Now you can use the JS variable "moonUnitAlpha" anywhere you want to grab that PHP string value. This seems to work really well for us. We'll see if it holds up to heavy use.

On Selenium WebDriver how to get Text from Span Tag

You need to locate the element and use getText() method to extract the text.

WebElement element = driver.findElement("customSelect_3"));

Loop over array dimension in plpgsql

Since PostgreSQL 9.1 there is the convenient FOREACH:

   m   varchar[];
   arr varchar[] := array[['key1','val1'],['key2','val2']];
      RAISE NOTICE 'another_func(%,%)',m[1], m[2];

Solution for older versions:

   arr varchar[] := '{{key1,val1},{key2,val2}}';
   FOR i IN array_lower(arr, 1) .. array_upper(arr, 1)
      RAISE NOTICE 'another_func(%,%)',arr[i][1], arr[i][2];

Also, there is no difference between varchar[] and varchar[][] for the PostgreSQL type system. I explain in more detail here.

The DO statement requires at least PostgreSQL 9.0, and LANGUAGE plpgsql is the default (so you can omit the declaration).

How do I use SELECT GROUP BY in DataTable.Select(Expression)?

    .GroupBy(r => new { Col1 = r["Col1"], Col2 = r["Col2"] })
    .Select(g =>
        var row = dt.NewRow();

        row["PK"] = g.Min(r => r.Field<int>("PK"));
        row["Col1"] = g.Key.Col1;
        row["Col2"] = g.Key.Col2;

        return row;


Using awk to print all columns from the nth to the last

will print all but very first column:

awk '{$1=""; print $0}' somefile

will print all but two first columns:

awk '{$1=$2=""; print $0}' somefile

How to embed a Google Drive folder in a website

Google Drive folders can be embedded and displayed in list and grid views:

List view

<iframe src="" style="width:100%; height:600px; border:0;"></iframe>

Grid view

<iframe src="" style="width:100%; height:600px; border:0;"></iframe>

Q: What is a folder ID (FOLDER-ID) and how can I get it?

A: Go to Google Drive >> open the folder >> look at its URL in the address bar of your browser. For example:

Folder URL:

Folder ID:

Caveat with folders requiring permission

This technique works best for folders with public access. Folders that are shared only with certain Google accounts will cause trouble when you embed them this way. At the time of this edit, a message "You need permission" appears, with some buttons to help you "Request access" or "Switch accounts" (or possibly sign-in to a Google account). The Javascript in these buttons doesn't work properly inside an IFRAME in Chrome.

Read more at!msg/drive/GpVgCobPL2Y/_Xt7sMc1WzoJ

Exiting from python Command Line

This works for me, best way to come out of python prompt.


selecting unique values from a column

The rest are almost correct, except they should order by Date DESC


Where does npm install packages?

If you're trying to access your global dir from code, you can backtrack from process.execPath. For example, to find wsproxy, which is in {NODE_GLOBAL_DIR}/bin/wsproxy, you can just:

path.join(path.dirname(process.execPath), 'wsproxy')

There's also how the npm cli works @ ec9fcc1/lib/npm.js#L254 with:

path.resolve(process.execPath, '..', '..')

See also ec9fcc1/lib/install.js#L521:

var globalPackage = path.resolve(npm.globalPrefix,
                                 'lib', 'node_modules', moduleName(pkg))

Where globalPrefix has a default set in ec9fcc1/lib/config/defaults.js#L92-L105 of:

if (process.env.PREFIX) {
    globalPrefix = process.env.PREFIX
} else if (process.platform === 'win32') {
    // c:\node\node.exe --> prefix=c:\node\
    globalPrefix = path.dirname(process.execPath)
} else {
    // /usr/local/bin/node --> prefix=/usr/local
    globalPrefix = path.dirname(path.dirname(process.execPath))

    // destdir only is respected on Unix
    if (process.env.DESTDIR) {
        globalPrefix = path.join(process.env.DESTDIR, globalPrefix)

Is it possible to put CSS @media rules inline?

Inline styles cannot currently contain anything other than declarations (property: value pairs).

You can use style elements with appropriate media attributes in head section of your document.

How can I set / change DNS using the command-prompt at windows 8

I wrote this script for switching DNS servers of all currently enabled interfaces to specific address:

@echo off

:: Google DNS
set DNS1=
set DNS2=

for /f "tokens=1,2,3*" %%i in ('netsh int show interface') do (
    if %%i equ Enabled (
        echo Changing "%%l" : %DNS1% + %DNS2%
        netsh int ipv4 set dns name="%%l" static %DNS1% primary validate=no
        netsh int ipv4 add dns name="%%l" %DNS2% index=2 validate=no

ipconfig /flushdns


How can I run multiple curl requests processed sequentially?

You can specify any amount of URLs on the command line. They will be fetched in a sequential manner in the specified order.


For me the issue was VPN, I disconnected the VPN and "npm i" command worked with no fail.

Laravel PDOException SQLSTATE[HY000] [1049] Unknown database 'forge'

OK, found solution.

In the file database.php, by default, it comes the "mysql" part:

 'mysql' => [
            'driver' => 'mysql',
            'host' => env('DB_HOST', ''),
            'port' => env('DB_PORT', '3306'),
            'database' => env('DB_DATABASE', 'forge'),
            'username' => env('DB_USERNAME', 'forge'),
            'password' => env('DB_PASSWORD', ''),
            'charset' => 'utf8mb4',
            'collation' => 'utf8mb4_unicode_ci',
            'prefix' => '',
            'strict' => true,
            'engine' => null,

all you need to do is change the values :

'database' => env('DB_DATABASE', 'forge'),
'username' => env('DB_USERNAME', 'forge'),

by your database name (you must create one if you dont have any) and by that database username

like this

'database' => env('DB_DATABASE', 'MyDatabase'),
'username' => env('DB_USERNAME', 'MyUsername'),

How can I check the syntax of Python script without executing it?

Thanks to the above answers @Rosh Oxymoron. I improved the script to scan all files in a dir that are python files. So for us lazy folks just give it the directory and it will scan all the files in that directory that are python.

import sys
import glob, os

for file in glob.glob("*.py"):
    source = open(file, 'r').read() + '\n'
    compile(source, file, 'exec')

Save this as and run python ~/YOURDirectoryTOCHECK

kill -3 to get java thread dump

With Java 8 in picture, jcmd is the preferred approach.

jcmd <PID> Thread.print

Following is the snippet from Oracle documentation :

The release of JDK 8 introduced Java Mission Control, Java Flight Recorder, and jcmd utility for diagnosing problems with JVM and Java applications. It is suggested to use the latest utility, jcmd instead of the previous jstack utility for enhanced diagnostics and reduced performance overhead.

However, shipping this with the application may be licensing implications which I am not sure.

JavaScript: Upload file

Pure JS

You can use fetch optionally with await-try-catch

let photo = document.getElementById("image-file").files[0];
let formData = new FormData();
formData.append("photo", photo);
fetch('/upload/image', {method: "POST", body: formData});

async function SavePhoto(inp) 
    let user = { name:'john', age:34 };
    let formData = new FormData();
    let photo = inp.files[0];      
    formData.append("photo", photo);
    formData.append("user", JSON.stringify(user)); 
    const ctrl = new AbortController()    // timeout
    setTimeout(() => ctrl.abort(), 5000);
    try {
       let r = await fetch('/upload/image', 
         {method: "POST", body: formData, signal: ctrl.signal}); 
       console.log('HTTP response code:',r.status); 
    } catch(e) {
       console.log('Huston we have problem...:', e);
<input id="image-file" type="file" onchange="SavePhoto(this)" >
Before selecting the file open chrome console > network tab to see the request details.
<small>Because in this example we send request to the response code will be 404 ofcourse...</small>

(in stack overflow snippets there is problem with error handling, however in <a href="">jsfiddle version</a> for 404 errors 4xx/5xx are <a href="">not throwing</a> at all but we can read response status which contains code)

Old school approach - xhr

let photo = document.getElementById("image-file").files[0];  // file from input
let req = new XMLHttpRequest();
let formData = new FormData();

formData.append("photo", photo);                       "POST", '/upload/image');

function SavePhoto(e) 
    let user = { name:'john', age:34 };
    let xhr = new XMLHttpRequest();
    let formData = new FormData();
    let photo = e.files[0];      
    formData.append("user", JSON.stringify(user));   
    formData.append("photo", photo);
    xhr.onreadystatechange = state => { console.log(xhr.status); } // err handling
    xhr.timeout = 5000;"POST", '/upload/image'); 
<input id="image-file" type="file" onchange="SavePhoto(this)" >
Choose file and open chrome console > network tab to see the request details.
<small>Because in this example we send request to the response code will be 404 ofcourse...</small>

(the stack overflow snippets, has some problem with error handling - the xhr.status is zero (instead of 404) which is similar to situation when we run script from file on <a href="">local disc</a> - so I provide also js fiddle version which shows proper http error code <a href="">here</a>)


  • In server side you can read original file name (and other info) which is automatically included to request by browser in filename formData parameter.
  • You do NOT need to set request header Content-Type to multipart/form-data - this will be set automatically by browser.
  • Instead of /upload/image you can use full address like http://.../upload/image.
  • If you want to send many files in single request use multiple attribute: <input multiple type=... />, and attach all chosen files to formData in similar way (e.g. photo2=...files[2];... formData.append("photo2", photo2);)
  • You can include additional data (json) to request e.g. let user = {name:'john', age:34} in this way: formData.append("user", JSON.stringify(user));
  • You can set timeout: for fetch using AbortController, for old approach by xhr.timeout= milisec
  • This solutions should work on all major browsers.