Programs & Examples On #Stripping

Removing spaces from a variable input using PowerShell 4.0

You're close. You can strip the whitespace by using the replace method like this:

$answer.replace(' ','')

There needs to be no space or characters between the second set of quotes in the replace method (replacing the whitespace with nothing).

Download files from server php

Here is the code that will not download courpt files

$filename = "myfile.jpg";
$file = "/uploads/images/".$filename;

header('Content-type: application/octet-stream');
header("Content-Type: ".mime_content_type($file));
header("Content-Disposition: attachment; filename=".$filename);
while (ob_get_level()) {

I have included mime_content_type which will return content type of file .

To prevent from corrupt file download i have added ob_get_level() and ob_end_clean();

C++ cout hex values?

std::hex is defined in <ios> which is included by <iostream>. But to use things like std::setprecision/std::setw/std::setfill/etc you have to include <iomanip>.

How to convert string to float?

Use atof()

But this is deprecated, use this instead:

const char* flt = "4.0800";
float f;
sscanf(flt, "%f", &f);

atof() returns 0 for both failure and on conversion of 0.0, best to not use it.

Best way to deploy Visual Studio application that can run without installing

It is possible and is deceptively easy:

  1. "Publish" the application (to, say, some folder on drive C), either from menu Build or from the project's properties ? Publish. This will create an installer for a ClickOnce application.
  2. But instead of using the produced installer, find the produced files (the EXE file and the .config, .manifest, and .application files, along with any DLL files, etc.) - they are all in the same folder and typically in the bin\Debug folder below the project file (.csproj).
  3. Zip that folder (leave out any *.vhost.* files and the app.publish folder (they are not needed), and the .pdb files unless you foresee debugging directly on your user's system (for example, by remote control)), and provide it to the users.

An added advantage is that, as a ClickOnce application, it does not require administrative privileges to run (if your application follows the normal guidelines for which folders to use for application data, etc.).

As for .NET, you can check for the minimum required version of .NET being installed (or at all) in the application (most users will already have it installed) and present a dialog with a link to the download page on the Microsoft website (or point to one of your pages that could redirect to the Microsoft page - this makes it more robust if the Microsoft URL change). As it is a small utility, you could target .NET 2.0 to reduce the probability of a user to have to install .NET.

It works. We use this method during development and test to avoid having to constantly uninstall and install the application and still being quite close to how the final application will run.

Why can't I use a list as a dict key in python?

The issue is that tuples are immutable, and lists are not. Consider the following

d = {}
li = [1,2,3]
d[li] = 5

What should d[li] return? Is it the same list? How about d[[1,2,3]]? It has the same values, but is a different list?

Ultimately, there is no satisfactory answer. For example, if the only key that works is the original key, then if you have no reference to that key, you can never again access the value. With every other allowed key, you can construct a key without a reference to the original.

If both of my suggestions work, then you have very different keys that return the same value, which is more than a little surprising. If only the original contents work, then your key will quickly go bad, since lists are made to be modified.

Transpose/Unzip Function (inverse of zip)?

While numpy arrays and pandas may be preferrable, this function imitates the behavior of zip(*args) when called as unzip(args).

Allows for generators, like the result from zip in Python 3, to be passed as args as it iterates through values.

def unzip(items, cls=list, ocls=tuple):
    """Zip function in reverse.

    :param items: Zipped-like iterable.
    :type  items: iterable

    :param cls: Container factory. Callable that returns iterable containers,
        with a callable append attribute, to store the unzipped items. Defaults
        to ``list``.
    :type  cls: callable, optional

    :param ocls: Outer container factory. Callable that returns iterable
        containers. with a callable append attribute, to store the inner
        containers (see ``cls``). Defaults to ``tuple``.
    :type  ocls: callable, optional

    :returns: Unzipped items in instances returned from ``cls``, in an instance
        returned from ``ocls``.
    # iter() will return the same iterator passed to it whenever possible.
    items = iter(items)

        i = next(items)
    except StopIteration:
        return ocls()

    unzipped = ocls(cls([v]) for v in i)

    for i in items:
        for c, v in zip(unzipped, i):

    return unzipped

To use list cointainers, simply run unzip(zipped), as

unzip(zip(["a","b","c"],[1,2,3])) == (["a","b","c"],[1,2,3])

To use deques, or other any container sporting append, pass a factory function.

from collections import deque

unzip([("a",1),("b",2)], deque, list) == [deque(["a","b"]),deque([1,2])]

(Decorate cls and/or main_cls to micro manage container initialization, as briefly shown in the final assert statement above.)

Double vs. BigDecimal?

There are two main differences from double:

  • Arbitrary precision, similarly to BigInteger they can contain number of arbitrary precision and size
  • Base 10 instead of Base 2, a BigDecimal is n*10^scale where n is an arbitrary large signed integer and scale can be thought of as the number of digits to move the decimal point left or right

The reason you should use BigDecimal for monetary calculations is not that it can represent any number, but that it can represent all numbers that can be represented in decimal notion and that include virtually all numbers in the monetary world (you never transfer 1/3 $ to someone).

Replacing a fragment with another fragment inside activity group

You Can Use This code

((AppCompatActivity) getActivity()).getSupportFragmentManager().beginTransaction().replace(, new YourFragment()).commit();

or You Can This Use Code

YourFragment fragments=(YourFragment) getSupportFragmentManager().findFragmentById(;

        if (fragments==null) {
            getSupportFragmentManager().beginTransaction().replace(, new Fragment_News()).commit();

Google Maps API v3 marker with label

In order to add a label to the map you need to create a custom overlay. The sample at uses a custom class, Layer, that inherits from OverlayView (which inherits from MVCObject) from the Google Maps API. He has a revised version (adds support for visibility, zIndex and a click event) which can be found here:

The following code is taken directly from Marc Ridey's Blog (the revised link above).

Layer class

// Define the overlay, derived from google.maps.OverlayView
function Label(opt_options) {
  // Initialization

  // Label specific
  var span = this.span_ = document.createElement('span'); = 'position: relative; left: -50%; top: -8px; ' +
  'white-space: nowrap; border: 1px solid blue; ' +
  'padding: 2px; background-color: white';

  var div = this.div_ = document.createElement('div');
  div.appendChild(span); = 'position: absolute; display: none';
Label.prototype = new google.maps.OverlayView;

// Implement onAdd
Label.prototype.onAdd = function() {
  var pane = this.getPanes().overlayImage;

  // Ensures the label is redrawn if the text or position is changed.
  var me = this;
  this.listeners_ = [
    google.maps.event.addListener(this, 'position_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'visible_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'clickable_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'text_changed', function() { me.draw(); }),
    google.maps.event.addListener(this, 'zindex_changed', function() { me.draw(); }),
    google.maps.event.addDomListener(this.div_, 'click', function() {
      if (me.get('clickable')) {
        google.maps.event.trigger(me, 'click');

// Implement onRemove
Label.prototype.onRemove = function() {

 // Label is removed from the map, stop updating its position/text.
 for (var i = 0, I = this.listeners_.length; i < I; ++i) {

// Implement draw
Label.prototype.draw = function() {
 var projection = this.getProjection();
 var position = projection.fromLatLngToDivPixel(this.get('position'));

 var div = this.div_; = position.x + 'px'; = position.y + 'px'; = 'block';

 this.span_.innerHTML = this.get('text').toString();


    <meta http-equiv="content-type" content="text/html; charset=utf-8">
      Label Overlay Example
    <script type="text/javascript" src=""></script>
    <script type="text/javascript" src="label.js"></script>
    <script type="text/javascript">
      var marker;

      function initialize() {
        var latLng = new google.maps.LatLng(40, -100);

        var map = new google.maps.Map(document.getElementById('map_canvas'), {
          zoom: 5,
          center: latLng,
          mapTypeId: google.maps.MapTypeId.ROADMAP

        marker = new google.maps.Marker({
          position: latLng,
          draggable: true,
          zIndex: 1,
          map: map,
          optimized: false

        var label = new Label({
          map: map
        label.bindTo('position', marker);
        label.bindTo('text', marker, 'position');
        label.bindTo('visible', marker);
        label.bindTo('clickable', marker);
        label.bindTo('zIndex', marker);

        google.maps.event.addListener(marker, 'click', function() { alert('Marker has been clicked'); })
        google.maps.event.addListener(label, 'click', function() { alert('Label has been clicked'); })

      function showHideMarker() {

      function pinUnpinMarker() {
        var draggable = marker.getDraggable();
  <body onload="initialize()">
    <div id="map_canvas" style="height: 200px; width: 200px"></div>
    <button type="button" onclick="showHideMarker();">Show/Hide Marker</button>
    <button type="button" onclick="pinUnpinMarker();">Pin/Unpin Marker</button>

NameError: global name 'unicode' is not defined - in Python 3

One can replace unicode with u''.__class__ to handle the missing unicode class in Python 3. For both Python 2 and 3, you can use the construct

isinstance(unicode_or_str, u''.__class__)


type(unicode_or_str) == type(u'')

Depending on your further processing, consider the different outcome:

Python 3

>>> isinstance('text', u''.__class__)
>>> isinstance(u'text', u''.__class__)

Python 2

>>> isinstance(u'text', u''.__class__)
>>> isinstance('text', u''.__class__)

Get current folder path

If you want the exe path you can use System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetEntryAssembly().Location);

How to parseInt in Angular.js

Inside template this working finely.

<!DOCTYPE html>
<script src=""></script>

<div ng-app="">
<input ng-model="name" value="0">
<p>My first expression: {{ (name-0) + 5 }}</p>


XmlSerializer: remove unnecessary xsi and xsd namespaces

There is an alternative - you can provide a member of type XmlSerializerNamespaces in the type to be serialized. Decorate it with the XmlNamespaceDeclarations attribute. Add the namespace prefixes and URIs to that member. Then, any serialization that does not explicitly provide an XmlSerializerNamespaces will use the namespace prefix+URI pairs you have put into your type.

Example code, suppose this is your type:

[XmlRoot(Namespace = "urn:mycompany.2009")]
public class Person {
  public bool Known;
  public string Name;
  public XmlSerializerNamespaces xmlns;

You can do this:

var p = new Person
      Name = "Charley",
      Known = false, 
      xmlns = new XmlSerializerNamespaces()
p.xmlns.Add("",""); // default namespace is emoty
p.xmlns.Add("c", "urn:mycompany.2009");

And that will mean that any serialization of that instance that does not specify its own set of prefix+URI pairs will use the "p" prefix for the "urn:mycompany.2009" namespace. It will also omit the xsi and xsd namespaces.

The difference here is that you are adding the XmlSerializerNamespaces to the type itself, rather than employing it explicitly on a call to XmlSerializer.Serialize(). This means that if an instance of your type is serialized by code you do not own (for example in a webservices stack), and that code does not explicitly provide a XmlSerializerNamespaces, that serializer will use the namespaces provided in the instance.

How can I make a multipart/form-data POST request using Java?

If size of the JARs matters (e.g. in case of applet), one can also directly use httpmime with instead of HttpClient.

httpclient-4.2.4:      423KB
httpmime-4.2.4:         26KB
httpcore-4.2.4:        222KB
commons-codec-1.6:     228KB
commons-logging-1.1.1:  60KB
Sum:                   959KB

httpmime-4.2.4:         26KB
httpcore-4.2.4:        222KB
Sum:                   248KB


HttpURLConnection connection = (HttpURLConnection) url.openConnection();

FileBody fileBody = new FileBody(new File(fileName));
MultipartEntity multipartEntity = new MultipartEntity(HttpMultipartMode.STRICT);
multipartEntity.addPart("file", fileBody);

connection.setRequestProperty("Content-Type", multipartEntity.getContentType().getValue());
OutputStream out = connection.getOutputStream();
try {
} finally {
int status = connection.getResponseCode();

Dependency in pom.xml:


What's the Kotlin equivalent of Java's String[]?

This example works perfectly in Android

In kotlin you can use a lambda expression for this. The Kotlin Array Constructor definition is:

Array(size: Int, init: (Int) -> T)

Which evaluates to:

skillsSummaryDetailLinesArray = Array(linesLen) {
        i: Int -> skillsSummaryDetailLines!!.getString(i)


skillsSummaryDetailLinesArray = Array<String>(linesLen) {
        i: Int -> skillsSummaryDetailLines!!.getString(i)

In this example the field definition was:

private var skillsSummaryDetailLinesArray: Array<String>? = null

Hope this helps

Download and open PDF file using Ajax

To fix the blank PDF issue in post request to get stream data like PDF, we need to add response type as 'arraybuffer' or 'blob' in request

  url: '<URL>',
  type: "POST",
  dataType: 'arraybuffer',
  success: function(data) {
    let blob = new Blob([data], {type: 'arraybuffer'});
    let link = document.createElement('a');
    let objectURL = window.URL.createObjectURL(blob);
    link.href = objectURL; = '_self'; = "fileName.pdf";
    (document.body || document.documentElement).appendChild(link);;
    }, 100);

why I can't get value of label with jquery and javascript?

Label's aren't form elements. They don't have a value. They have innerHTML and textContent.


// or


var telefon = document.getElementById('telefon');

If you are starting with your form element, check out the labels list of it. That is,

var el = $('#myformelement');
var label = $( el.prop('labels') );
// label.html();
// el.val();
// blah blah blah you get the idea

How do I tell Maven to use the latest version of a dependency?

By the time this question was posed there were some kinks with version ranges in maven, but these have been resolved in newer versions of maven. This article captures very well how version ranges work and best practices to better understand how maven understands versions:

How to convert a Binary String to a base 10 integer in Java

Fixed version of java's Integer.parseInt(text) to work with negative numbers:

public static int parseInt(String binary) {
    if (binary.length() < Integer.SIZE) return Integer.parseInt(binary, 2);

    int result = 0;
    byte[] bytes = binary.getBytes();

    for (int i = 0; i < bytes.length; i++) {
        if (bytes[i] == 49) {
            result = result | (1 << (bytes.length - 1 - i));

    return result;

Eclipse executable launcher error: Unable to locate companion shared library

This happened to me when I tried to open eclipse.exe before the .zip file finished extracting. Make sure all dependencies are unzipped or unpacked before opening the .exe.

when do you need .ascx files and how would you use them?

ASCX files are server-side Web application framework designed for Web development to produce dynamic Web pages.They like DLL codes but you can use there's TAGS You can write them once and use them in any places in your ASP pages.If you have a file named "Controll.ascx" then its code will named "Controll.ascx.cs". You can embed it in a ASP page to use it:

Install Application programmatically on Android

UpdateNode provides an API for Android to install APK packages from inside another App.

You can just define your Update online and integrate the API into your App - that's it.
Currently the API is in Beta state, but you can already do some tests yourself.

Beside that, UpdateNode offers also displaying messages though the system - pretty useful if you want to tell something important to your users.

I am part of the client dev team and am using at least the message functionality for my own Android App.

See here a description how to integrate the API

Convert data.frame column to a vector?

If you just use the extract operator it will work. By default, [] sets option drop=TRUE, which is what you want here. See ?'[' for more details.

>  a1 = c(1, 2, 3, 4, 5)
>  a2 = c(6, 7, 8, 9, 10)
>  a3 = c(11, 12, 13, 14, 15)
>  aframe = data.frame(a1, a2, a3)
> aframe[,'a2']
[1]  6  7  8  9 10
> class(aframe[,'a2'])
[1] "numeric"

How to check if a div is visible state or not?

You can use (':hidden') method to find if your div is visible or not.. Also its a good practice to cache a element if you are using it multiple times in your code..

$(".subpanel a").click(function() 
        var chatterNickname = $(this).text();
        var $chatPanel = $("#singlechatpanel-1");

            alert("Room 1 is filled.");
            $("#singlechatpanel-1 #chatter_nickname").html("Chatting with: " + chatterNickname);

How to center a "position: absolute" element

Using left: calc(50% - Wpx/2); where W is the width of the element works for me.

How can I scale an entire web page with CSS?

Scale is not the best option

It will need some other adjustments, like margins paddings etc ..

but the right option is

zoom: 75%

The type initializer for 'MyClass' threw an exception

Noteworthy: I had multiple projects in my solution and I forgot to add the references/Nuget libraries. When I ran a method in the static class, which used the given libraries, it threw the exception mentioned.

Performing user authentication in Java EE / JSF using j_security_check

The issue HttpServletRequest.login does not set authentication state in session has been fixed in 3.0.1. Update glassfish to the latest version and you're done.

Updating is quite straightforward:

glassfishv3/bin/pkg set-authority -P
glassfishv3/bin/pkg image-update

PHP: Return all dates between two dates in an array

Solution for PHP 5.2 with DateTime objects. But startDate MUST be before endDate.

function createRange($startDate, $endDate) {
    $tmpDate = new DateTime($startDate);
    $tmpEndDate = new DateTime($endDate);

    $outArray = array();
    do {
        $outArray[] = $tmpDate->format('Y-m-d');
    } while ($tmpDate->modify('+1 day') <= $tmpEndDate);

    return $outArray;


$dates = createRange('2010-10-01', '2010-10-05');

$dates contain:

Array( '2010-10-01', '2010-10-02', '2010-10-03', '2010-10-04', '2010-10-05' )       

Package structure for a Java project?

There are a few existing resources you might check:

  1. Properly Package Your Java Classes
  2. Spring 2.5 Architecture
  3. Java Tutorial - Naming a Package
  4. SUN Naming Conventions

For what it's worth, my own personal guidelines that I tend to use are as follows:

  1. Start with reverse domain, e.g. "com.mycompany".
  2. Use product name, e.g. "myproduct". In some cases I tend to have common packages that do not belong to a particular product. These would end up categorized according to the functionality of these common classes, e.g. "io", "util", "ui", etc.
  3. After this it becomes more free-form. Usually I group according to project, area of functionality, deployment, etc. For example I might have "project1", "project2", "ui", "client", etc.

A couple of other points:

  1. It's quite common in projects I've worked on for package names to flow from the design documentation. Usually products are separated into areas of functionality or purpose already.
  2. Don't stress too much about pushing common functionality into higher packages right away. Wait for there to be a need across projects, products, etc., and then refactor.
  3. Watch inter-package dependencies. They're not all bad, but it can signify tight coupling between what might be separate units. There are tools that can help you keep track of this.

How to enter special characters like "&" in oracle database?

If you are in SQL*Plus or SQL Developer, you want to run

SQL> set define off;

before executing the SQL statement. That turns off the checking for substitution variables.

SET directives like this are instructions for the client tool (SQL*Plus or SQL Developer). They have session scope, so you would have to issue the directive every time you connect (you can put the directive in your client machine's glogin.sql if you want to change the default to have DEFINE set to OFF). There is no risk that you would impact any other user or session in the database.

Datetime BETWEEN statement not working in SQL Server

Does the second query return any results from the 17th, or just from the 18th?

The first query will only return results from the 17th, or midnight on the 18th.

Try this instead

select * 
from LOGS 
where check_in >= CONVERT(datetime,'2013-10-17') 
and check_in< CONVERT(datetime,'2013-10-19')

How to remove all duplicate items from a list

for unhashable lists. It is faster as it does not iterate about already checked entries.

def purge_dublicates(X):
    unique_X = []
    for i, row in enumerate(X):
        if row not in X[i + 1:]:
    return unique_X

Find an element in DOM based on an attribute value

FindByAttributeValue("Attribute-Name", "Attribute-Value");   

p.s. if you know exact element-type, you add 3rd parameter (i.e.div, a, p ...etc...):

FindByAttributeValue("Attribute-Name", "Attribute-Value", "div");   

but at first, define this function:

function FindByAttributeValue(attribute, value, element_type)    {
  element_type = element_type || "*";
  var All = document.getElementsByTagName(element_type);
  for (var i = 0; i < All.length; i++)       {
    if (All[i].getAttribute(attribute) == value) { return All[i]; }

p.s. updated per comments recommendations.

How can I determine the URL that a local Git repository was originally cloned from?

With Git 2.7 (release January 5th, 2015), you have a more coherent solution using git remote:

git remote get-url origin

(nice pendant of git remote set-url origin <newurl>)

See commit 96f78d3 (16 Sep 2015) by Ben Boeckel (mathstuf).
(Merged by Junio C Hamano -- gitster -- in commit e437cbd, 05 Oct 2015):

remote: add get-url subcommand

Expanding insteadOf is a part of ls-remote --url and there is no way to expand pushInsteadOf as well.
Add a get-url subcommand to be able to query both as well as a way to get all configured URLs.


Retrieves the URLs for a remote.
Configurations for insteadOf and pushInsteadOf are expanded here.
By default, only the first URL is listed.

  • With '--push', push URLs are queried rather than fetch URLs.
  • With '--all', all URLs for the remote will be listed.

Before git 2.7, you had:

 git config --get remote.[REMOTE].url
 git ls-remote --get-url [REMOTE]
 git remote show [REMOTE]

How to do a simple file search in cmd

Problem with DIR is that it will return wrong answers. If you are looking for DOC in a folder by using DIR *.DOC it will also give you the DOCX. Searching for *.HTM will also give the HTML and so on...

How do you install an APK file in the Android emulator?

Let's suppose you have to install Facebook APK on your emulator.

You can use adb to install the APK to the running emulator in OS X like this:

./adb install ~/FBAndroid-2.1.apk

And on Windows, like this:

adb install %HOMEPATH%\FBAndroid-2.1.apk

Once complete, check the apps screen of the emulator to check that the app has been installed correctly. If you need to force the upgrade of this app from a previous version, add the -r flag, like this on OS X:

./adb install -r ~/FBAndroid-2.1.apk

Converting an int or String to a char array on Arduino

None of that stuff worked. Here's a much simpler way .. the label str is the pointer to what IS an array...

String str = String(yourNumber, DEC); // Obviously .. get your int or byte into the string

str = str + '\r' + '\n'; // Add the required carriage return, optional line feed

byte str_len = str.length();

// Get the length of the whole lot .. C will kindly
// place a null at the end of the string which makes
// it by default an array[].
// The [0] element is the highest digit... so we
// have a separate place counter for the array...

byte arrayPointer = 0;

while (str_len)
    // I was outputting the digits to the TX buffer

    if ((UCSR0A & (1<<UDRE0))) // Is the TX buffer empty?
        UDR0 = str[arrayPointer];

How do I center an anchor element in CSS?

I think you can't do that with inline elements like anchor, span. But to make it work you have to set the display to block.

<a href="" style="text-align:center;display:block;">example</a>

Secure FTP using Windows batch script

First, make sure you understand, if you need to use Secure FTP (=FTPS, as per your text) or SFTP (as per tag you have used).

Neither is supported by Windows command-line ftp.exe. As you have suggested, you can use WinSCP. It supports both FTPS and SFTP.

Using WinSCP, your batch file would look like (for SFTP):

echo open sftp://ftp_user:[email protected] -hostkey="server's hostkey" >> ftpcmd.dat
echo put c:\directory\%1-export-%date%.csv >> ftpcmd.dat
echo exit >> ftpcmd.dat /script=ftpcmd.dat
del ftpcmd.dat

And the batch file: /log=ftpcmd.log /script=ftpcmd.dat /parameter %1 %date%

Though using all capabilities of WinSCP (particularly providing commands directly on command-line and the %TIMESTAMP% syntax), the batch file simplifies to: /log=ftpcmd.log /command ^
    "open sftp://ftp_user:[email protected] -hostkey=""server's hostkey""" ^
    "put c:\directory\%1-export-%%TIMESTAMP#yyyymmdd%%.csv" ^

For the purpose of -hostkey switch, see verifying the host key in script.

Easier than assembling the script/batch file manually is to setup and test the connection settings in WinSCP GUI and then have it generate the script or batch file for you:

Generate batch file

All you need to tweak is the source file name (use the %TIMESTAMP% syntax as shown previously) and the path to the log file.

For FTPS, replace the sftp:// in the open command with ftpes:// (explicit TLS/SSL) or ftps:// (implicit TLS/SSL). Remove the -hostkey switch. /log=ftpcmd.log /command ^
    "open ftps://ftp_user:[email protected] -explicit" ^
    "put c:\directory\%1-export-%%TIMESTAMP#yyyymmdd%%.csv" ^

You may need to add the -certificate switch, if your server's certificate is not issued by a trusted authority.

Again, as with the SFTP, easier is to setup and test the connection settings in WinSCP GUI and then have it generate the script or batch file for you.

See a complete conversion guide from ftp.exe to WinSCP.

You should also read the Guide to automating file transfers to FTP server or SFTP server.

Note to using %TIMESTAMP#yyyymmdd% instead of %date%: A format of %date% variable value is locale-specific. So make sure you test the script on the same locale you are actually going to use the script on. For example on my Czech locale the %date% resolves to ct 06. 11. 2014, what might be problematic when used as a part of a file name.

For this reason WinSCP supports (locale-neutral) timestamp formatting natively. For example %TIMESTAMP#yyyymmdd% resolves to 20170515 on any locale.

(I'm the author of WinSCP)

Update Tkinter Label from variable

This is the easiest one , Just define a Function and then a Tkinter Label & Button . Pressing the Button changes the text in the label. The difference that you would when defining the Label is that use the text variable instead of text. Code is tested and working.

    from tkinter import *
    master = Tk()
    def change_text():
        my_var.set("Second click")
    my_var = StringVar()
    my_var.set("First click")
    label = Label(mas,textvariable=my_var,fg="red")
    button = Button(mas,text="Submit",command = change_text)

force css grid container to fill full screen of device

If you take advantage of width: 100vw; and height: 100vh;, the object with these styles applied will stretch to the full width and height of the device.

Also note, there are times padding and margins can get added to your view, by browsers and the like. I added a * global no padding and margins so you can see the difference. Keep this in mind.

  box-sizing: border-box;_x000D_
  padding: 0;_x000D_
  margin: 0;_x000D_
.wrapper {_x000D_
  display: grid;_x000D_
  border-style: solid;_x000D_
  border-color: red;_x000D_
  grid-template-columns: repeat(3, 1fr);_x000D_
  grid-template-rows: repeat(3, 1fr);_x000D_
  grid-gap: 10px;_x000D_
  width: 100vw;_x000D_
  height: 100vh;_x000D_
.one {_x000D_
  border-style: solid;_x000D_
  border-color: blue;_x000D_
  grid-column: 1 / 3;_x000D_
  grid-row: 1;_x000D_
.two {_x000D_
  border-style: solid;_x000D_
  border-color: yellow;_x000D_
  grid-column: 2 / 4;_x000D_
  grid-row: 1 / 3;_x000D_
.three {_x000D_
  border-style: solid;_x000D_
  border-color: violet;_x000D_
  grid-row: 2 / 5;_x000D_
  grid-column: 1;_x000D_
.four {_x000D_
  border-style: solid;_x000D_
  border-color: aqua;_x000D_
  grid-column: 3;_x000D_
  grid-row: 3;_x000D_
.five {_x000D_
  border-style: solid;_x000D_
  border-color: green;_x000D_
  grid-column: 2;_x000D_
  grid-row: 4;_x000D_
.six {_x000D_
  border-style: solid;_x000D_
  border-color: purple;_x000D_
  grid-column: 3;_x000D_
  grid-row: 4;_x000D_
<div class="wrapper">_x000D_
  <div class="one">One</div>_x000D_
  <div class="two">Two</div>_x000D_
  <div class="three">Three</div>_x000D_
  <div class="four">Four</div>_x000D_
  <div class="five">Five</div>_x000D_
  <div class="six">Six</div>_x000D_

How to get position of a certain element in strings vector, to use it as an index in ints vector?

To get a position of an element in a vector knowing an iterator pointing to the element, simply subtract v.begin() from the iterator:

ptrdiff_t pos = find(Names.begin(), Names.end(), old_name_) - Names.begin();

Now you need to check pos against Names.size() to see if it is out of bounds or not:

if(pos >= Names.size()) {
    //old_name_ not found

vector iterators behave in ways similar to array pointers; most of what you know about pointer arithmetic can be applied to vector iterators as well.

Starting with C++11 you can use std::distance in place of subtraction for both iterators and pointers:

ptrdiff_t pos = distance(Names.begin(), find(Names.begin(), Names.end(), old_name_));

IntelliJ cannot find any declarations

I was having similar issues in my IntelliJ mvn project. Pom.xml was not recognized. What worked for me was right click on the pom.xml and then add as a maven project.

get all keys set in memcached

The easiest way is to use python-memcached-stats package,

The keys() method should get you going.

Example -

from memcached_stats import MemcachedStats
mem = MemcachedStats()

 ... ]

React-Native: Module AppRegistry is not a registered callable module

For me just restarting the computer fixed it. (My error was "module appRegistry is not a registered callable module (calling runapplication) js engine: hermes")

Another top answer that is missing here and might have worked was just to kill node processes:

killall -9 node

[ Module AppRegistry is not registered callable module (calling runApplication) ]

How to reset / remove chrome's input highlighting / focus border?

you could just set outline: none; and border to a different color on focus.

Creating a config file in PHP

I normally end up creating a single conn.php file that has my database connections. Then i include that file in all files that require database queries.

Maven Error: Could not find or load main class

Please follow the below snippet.. it works..

<project xmlns="" xmlns:xsi=""
    <description>Sample Project</description>
        <!-- mention your dependencies here -->

Please note, you have to provide the full classified class name (class name including package name without .java or .class) of main class inside <mainClass></mainClass> tag.

How can I write a byte array to a file in Java?

         File file = ...
         byte[] data = ...
            FileOutputStream fos = FileOutputStream(file);
         }catch(Exception e){

but if the bytes array length is more than 1024 you should use loop to write the data.

jQuery: what is the best way to restrict "number"-only input for textboxes? (allow decimal points)

The best way is to check the contects of the text box whenever it loses focus.

You can check whether the contents are a "number" using a regular expression.

Or you can use the Validation plugin, which basically does this automatically.

Webfont Smoothing and Antialiasing in Firefox and Opera

Case: Light text with jaggy web font on dark background Firefox (v35)/Windows
Example: Google Web Font Ruda

Surprising solution -
adding following property to the applied selectors:

selector {
    text-shadow: 0 0 0;

Actually, result is the same just with text-shadow: 0 0;, but I like to explicitly set blur-radius.

It's not an universal solution, but might help in some cases. Moreover I haven't experienced (also not thoroughly tested) negative performance impacts of this solution so far.

Cannot delete directory with Directory.Delete(path, true)

I´ve solved with this millenary technique (you can leave the Thread.Sleep on his own in the catch)

bool deleted = false;
                Directory.Delete(rutaFinal, true);                    
                deleted = true;
            catch (Exception e)
                string mensaje = e.Message;
                if( mensaje == "The directory is not empty.")
        } while (deleted == false);

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

Take a look at this forum Theres a discussion on how using wildcards can lead to conflicts if you add new classes to the packages and if there are two classes with the same name in different packages where only one of them will be imported.


It gives that warning because your the line should actually be

List<Integer> i = new ArrayList<Integer>(Arrays.asList(0,1,2,3,4,5,6,7,8,9,10));
List<Integer> j = new ArrayList<Integer>();

You need to specify the type for array list or the compiler will give that warning because it cannot identify that you are using the list in a type safe way.

Find a file by name in Visual Studio Code

When you have opened a folder in a workspace you can do Ctrl+P (Cmd+P on Mac) and start typing the filename, or extension to filter the list of filenames

if you have:

  • plugin.ts
  • page.css
  • plugger.ts

You can type css and press enter and it will open the page.css. If you type .ts the list is filtered and contains two items.

Apache2: 'AH01630: client denied by server configuration'

For Wamp 3 (Apache 2.4), besides putting the server online as described in the other answers, in the Virtual Hosts file conf/extra/httpd-vhosts.conf
you might need to replace

Require local


Require all granted

This is applicable if in httpd.conf you have

Include conf/extra/httpd-vhosts.conf

How to get started with Windows 7 gadgets

Here's an MSDN article on Vista Gadgets. Some preliminary documentation on 7 gadgets, and changes. I think the only major changes are that Gadgets don't reside in the Sidebar anymore, and as such "dock/undock events" are now backwards-compatibility cludges that really shouldn't be used.

Best way to get started is probably to just tweak an existing gadget. There's an example gadget in the above link, or you could pick a different one out on your own.

Gadgets are written in HTML, CSS, and some IE scripting language (generally Javascript, but I believe VBScript also works). For really fancy things you might need to create an ActiveX object, so C#/C++ for COM could be useful to know.

Gadgets are packaged as ".gadget" files, which are just renamed Zip archives that contain a gadget manifest (gadget.xml) in their top level.

Unable to get spring boot to automatically create database schema

Sadly for me none of the answer given above worked because I later discovered that the issue came from my pom file. I used spring boot starter project and I added another kind of spring jpa which did not work. Initially I had this,


I replaced it with this:


Take note of the spring-boot-starter-data-jpa. Hopefully this may help someone. Check your pom file and ensure your dependencies match.

Origin null is not allowed by Access-Control-Allow-Origin

Adding a bit to use Gokhan's solution for using:


Now you just need to append above text in Target text followed by a space. make sure you close all the instances of chrome browser after adding above property. Now restart chrome by the icon where you added this property. It should work for all.

Spring @Transactional - isolation, propagation

Transaction Isolation and Transaction Propagation although related but are clearly two very different concepts. In both cases defaults are customized at client boundary component either by using Declarative transaction management or Programmatic transaction management. Details of each isolation levels and propagation attributes can be found in reference links below.

Transaction Isolation

For given two or more running transactions/connections to a database, how and when are changes made by queries in one transaction impact/visible to the queries in a different transaction. It also related to what kind of database record locking will be used to isolate changes in this transaction from other transactions and vice versa. This is typically implemented by database/resource that is participating in transaction.


Transaction Propagation

In an enterprise application for any given request/processing there are many components that are involved to get the job done. Some of this components mark the boundaries (start/end) of a transaction that will be used in respective component and it's sub components. For this transactional boundary of components, Transaction Propogation specifies if respective component will or will not participate in transaction and what happens if calling component already has or does not have a transaction already created/started. This is same as Java EE Transaction Attributes. This is typically implemented by the client transaction/connection manager.


Efficient way to insert a number into a sorted array of numbers?

Here's a comparison of four different algorithms for accomplishing this:


Naive is always horrible. It seems for small array sizes, the other three dont differ too much, but for larger arrays, the last 2 outperform the simple linear approach.

How to check if matching text is found in a string in Lua?

There are 2 options to find matching text; string.match or string.find.

Both of these perform a regex search on the string to find matches.


string.find(subject string, pattern string, optional start position, optional plain flag)

Returns the startIndex & endIndex of the substring found.

The plain flag allows for the pattern to be ignored and intead be interpreted as a literal. Rather than (tiger) being interpreted as a regex capture group matching for tiger, it instead looks for (tiger) within a string.

Going the other way, if you want to regex match but still want literal special characters (such as .()[]+- etc.), you can escape them with a percentage; %(tiger%).

You will likely use this in combination with string.sub


str = "This is some text containing the word tiger."
if string.find(str, "tiger") then
  print ("The word tiger was found.")
  print ("The word tiger was not found.")


string.match(s, pattern, optional index)

Returns the capture groups found.


str = "This is some text containing the word tiger."
if string.match(str, "tiger") then
  print ("The word tiger was found.")
  print ("The word tiger was not found.")

Ruby: Easiest Way to Filter Hash Keys?

In Ruby, the Hash#select is a right option. If you work with Rails, you can use Hash#slice and Hash#slice!. e.g. (rails 3.2.13)

h1 = {:a => 1, :b => 2, :c => 3, :d => 4}

h1.slice(:a, :b)         # return {:a=>1, :b=>2}, but h1 is not changed

h2 = h1.slice!(:a, :b)   # h1 = {:a=>1, :b=>2}, h2 = {:c => 3, :d => 4}

How can I wait In Node.js (JavaScript)? l need to pause for a period of time

The other answers are great but I thought I'd take a different tact.

If all you are really looking for is to slow down a specific file in linux:

 rm slowfile; mkfifo slowfile; perl -e 'select STDOUT; $| = 1; while(<>) {print $_; sleep(1) if (($ii++ % 5) == 0); }' myfile > slowfile  &

node myprog slowfile

This will sleep 1 sec every five lines. The node program will go as slow as the writer. If it is doing other things they will continue at normal speed.

The mkfifo creates a first-in-first-out pipe. It's what makes this work. The perl line will write as fast as you want. The $|=1 says don't buffer the output.

Which is faster: Stack allocation or Heap allocation

Stack allocation is much faster since all it really does is move the stack pointer. Using memory pools, you can get comparable performance out of heap allocation, but that comes with a slight added complexity and its own headaches.

Also, stack vs. heap is not only a performance consideration; it also tells you a lot about the expected lifetime of objects.

Using multiple delimiters in awk

Another one is to use the -F option but pass it regex to print the text between left and or right parenthesis ().

The file content:


The command:

awk -F"[()]" '{print $2}' filename



Using awk to just print the text between []:

Use awk -F'[][]' but awk -F'[[]]' will not work.

combining two data frames of different lengths

My idea is to get max of rows count of all data.frames and next append empty matrix to every data.frame if need. This method doesn't require additional packages, only base is used. Code looks following:

list.df <- list(data.frame(a = 1:10), data.frame(a = 1:5), data.frame(a = 1:3))

max.rows <- max(unlist(lapply(list.df, nrow), use.names = F))

list.df <- lapply(list.df, function(x) {
    na.count <- max.rows - nrow(x)
    if (na.count > 0L) { <- matrix(NA, na.count, ncol(x))
        colnames( <- colnames(x)
    } else {
}), list.df)

#     a  a  a
# 1   1  1  1
# 2   2  2  2
# 3   3  3  3
# 4   4  4 NA
# 5   5  5 NA
# 6   6 NA NA
# 7   7 NA NA
# 8   8 NA NA
# 9   9 NA NA
# 10 10 NA NA

How to update json file with python

def updateJsonFile():
    jsonFile = open("replayScript.json", "r") # Open the JSON file for reading
    data = json.load(jsonFile) # Read the JSON into the buffer
    jsonFile.close() # Close the JSON file

    ## Working with buffered content
    tmp = data["location"] 
    data["location"] = path
    data["mode"] = "replay"

    ## Save our changes to JSON file
    jsonFile = open("replayScript.json", "w+")

How to change the font color of a disabled TextBox?

In addition to the answer by @spoon16 and @Cheetah, I always set the tabstop property to False on the textbox to prevent the text from being selected by default.

Alternatively, you can also do something like this:

private void FormFoo_Load(...) {
    txtFoo.Select(0, 0);


private void FormFoo_Load(...) {
    txtFoo.SelectionLength = 0;

Using Java to pull data from a webpage?

The simplest solution (without depending on any third-party library or platform) is to create a URL instance pointing to the web page / link you want to download, and read the content using streams.

For example:


public class DownloadPage {

    public static void main(String[] args) throws IOException {

        // Make a URL to the web page
        URL url = new URL("");

        // Get the input stream through URL Connection
        URLConnection con = url.openConnection();
        InputStream is =con.getInputStream();

        // Once you have the Input Stream, it's just plain old Java IO stuff.

        // For this case, since you are interested in getting plain-text web page
        // I'll use a reader and output the text content to System.out.

        // For binary content, it's better to directly read the bytes from stream and write
        // to the target file.

        BufferedReader br = new BufferedReader(new InputStreamReader(is));

        String line = null;

        // read each line and write to System.out
        while ((line = br.readLine()) != null) {

Hope this helps.

How to update array value javascript?

function Update(key, value)
    for (var i = 0; i < array.length; i++) {
        if (array[i].Key == key) {
            array[i].Value = value; 

HTML Table cellspacing or padding just top / bottom


td {
  padding-top: 2px;
  padding-bottom: 2px;

Each GROUP BY expression must contain at least one column that is not an outer reference

To start with you can't do this:

having rid!=MAX(rid)

The HAVING clause can only contain things which are attributes of the aggregate groups.

In addition, 1, 2, 3 is not valid in GROUP BY in SQL Server - I think that's only valid in ORDER BY.

Can you explain why this isn't what you are looking for:

LEFT(SUBSTRING(batchinfo.datapath, PATINDEX('%[0-9][0-9][0-9]%', batchinfo.datapath), 8000), PATINDEX('%[^0-9]%', SUBSTRING(batchinfo.datapath, PATINDEX('%[0-9][0-9][0-9]%', batchinfo.datapath), 8000))-1),,
 from batchinfo join qvalues on batchinfo.rowid=qvalues.rowid
where LEN(datapath)>4
group by LEFT(SUBSTRING(batchinfo.datapath, PATINDEX('%[0-9][0-9][0-9]%', batchinfo.datapath), 8000), PATINDEX('%[^0-9]%', SUBSTRING(batchinfo.datapath, PATINDEX('%[0-9][0-9][0-9]%', batchinfo.datapath), 8000))-1),,

BATCH file asks for file or folder

The real trick is: Use a Backslash at the end of the target path where to copy the file. The /Y is for overwriting existing files, if you want no warnings.


xcopy /Y "C:\file\from\here.txt" "C:\file\to\here\"

How to Populate a DataTable from a Stored Procedure

You don't need to add the columns manually. Just use a DataAdapter and it's simple as:

DataTable table = new DataTable();
using(var con = new SqlConnection(ConfigurationManager.ConnectionStrings["DB"].ConnectionString))
using(var cmd = new SqlCommand("usp_GetABCD", con))
using(var da = new SqlDataAdapter(cmd))
   cmd.CommandType = CommandType.StoredProcedure;

Note that you even don't need to open/close the connection. That will be done implicitly by the DataAdapter.

The connection object associated with the SELECT statement must be valid, but it does not need to be open. If the connection is closed before Fill is called, it is opened to retrieve data, then closed. If the connection is open before Fill is called, it remains open.

How do I run a Python script on my web server?

Very simply, you can rename your Python script to "pythonscript.cgi". Post that in your cgi-bin directory, add the appropriate permissions and browse to it.

This is a great link you can start with.

Here's another good one.

Hope that helps.

EDIT (09/12/2015): The second link has long been removed. Replaced it with one that provides information referenced from the original.

Symfony2 : How to get form validation errors after binding the request to the form

Symfony 2.3 / 2.4:

This function get's all the errors. The ones on the form like "The CSRF token is invalid. Please try to resubmit the form." as well as additional errors on the form children which have no error bubbling.

private function getErrorMessages(\Symfony\Component\Form\Form $form) {
    $errors = array();

    foreach ($form->getErrors() as $key => $error) {
        if ($form->isRoot()) {
            $errors['#'][] = $error->getMessage();
        } else {
            $errors[] = $error->getMessage();

    foreach ($form->all() as $child) {
        if (!$child->isValid()) {
            $errors[$child->getName()] = $this->getErrorMessages($child);

    return $errors;

To get all errors as a string:

$string = var_export($this->getErrorMessages($form), true);

Symfony 2.5 / 3.0:

$string = (string) $form->getErrors(true, false);

Docs: (at the bottom: The method Form::getErrorsAsString() was removed)

Change Date Format(DD/MM/YYYY) in SQL SELECT Statement

Changed to:

SELECT FORMAT(SA.[RequestStartDate],'dd/MM/yyyy') as 'Service Start Date', SA.[RequestEndDate] as 'Service End Date', FROM (......)SA WHERE......

Have no idea which SQL engine you are using, for other SQL engine, CONVERT can be used in SELECT statement to change the format in the form you needed.

Redirect to external URI from ASP.NET MVC controller

Using JavaScript

 public ActionResult Index()
    return Content("<script>window.location = '';</script>");

Note: As @Jeremy Ray Brown said , This is not the best option but you might find useful in some situations.

Hope this helps.

Android - implementing startForeground for a service?

In my case It was totally different since I was not having activity to launch the service in Oreo.

Below are the steps which I used to resolve this foreground service issue -

public class SocketService extends Service {
    private String TAG = this.getClass().getSimpleName();

    public void onCreate() {
        Log.d(TAG, "Inside onCreate() API");
        if (Build.VERSION.SDK_INT >= 26) {
            NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this);
            mBuilder.setContentTitle("Notification Alert, Click Me!");
            mBuilder.setContentText("Hi, This is Android Notification Detail!");
            NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

            // notificationID allows you to update the notification later on.
            startForeground(100, mBuilder.mNotification);
        Toast.makeText(getApplicationContext(), "inside onCreate()", Toast.LENGTH_LONG).show();

    public int onStartCommand(Intent resultIntent, int resultCode, int startId) {
        Log.d(TAG, "inside onStartCommand() API");

        return startId;

    public void onDestroy() {
        Log.d(TAG, "inside onDestroy() API");


    public IBinder onBind(Intent intent) {
        // TODO Auto-generated method stub
        return null;

And after that to initiate this service I triggered below cmd -

adb -s " + serial_id + " shell am startforegroundservice -n com.test.socket.sample/.SocketService

So this helps me to start service without activity on Oreo devices :)

Delete entire row if cell contains the string X

This is not necessarily a VBA task - This specific task is easiest sollowed with Auto filter.

1.Insert Auto filter (In Excel 2010 click on home-> (Editing) Sort & Filter -> Filter)
2. Filter on the 'Websites' column
3. Mark the 'none' and delete them
4. Clear filter

Why is there no ForEach extension method on IEnumerable?

One workaround is to write .ToList().ForEach(x => ...).


Easy to understand - reader only needs to know what ships with C#, not any additional extension methods.

Syntactic noise is very mild (only adds a little extranious code).

Doesn't usually cost extra memory, since a native .ForEach() would have to realize the whole collection, anyway.


Order of operations isn't ideal. I'd rather realize one element, then act on it, then repeat. This code realizes all elements first, then acts on them each in sequence.

If realizing the list throws an exception, you never get to act on a single element.

If the enumeration is infinite (like the natural numbers), you're out of luck.

How to use multiprocessing with multiple arguments?

This might be another option. The trick is in the wrapper function that returns another function which is passed in to The code below reads an input array and for each (unique) element in it, returns how many times (ie counts) that element appears in the array, For example if the input is

np.eye(3) = [ [1. 0. 0.]
              [0. 1. 0.]
              [0. 0. 1.]]

then zero appears 6 times and one 3 times

import numpy as np
from multiprocessing.dummy import Pool as ThreadPool
from multiprocessing import cpu_count

def extract_counts(label_array):
    labels = np.unique(label_array)
    out = extract_counts_helper([label_array], labels)
    return out

def extract_counts_helper(args, labels):
    n = max(1, cpu_count() - 1)
    pool = ThreadPool(n)
    results = {}, results), labels)
    return results

def wrapper(argsin, results):
    def inner_fun(label):
        label_array = argsin[0]
        counts = get_label_counts(label_array, label)
        results[label] = counts
    return inner_fun

def get_label_counts(label_array, label):
    return sum(label_array.flatten() == label)

if __name__ == "__main__":
    img = np.ones([2,2])
    out = extract_counts(img)
    print('input array: \n', img)
    print('label counts: ', out)
    img = np.eye(3)
    out = extract_counts(img)
    print('input array: \n', img)
    print('label counts: ', out)
    img = np.random.randint(5, size=(3, 3))
    out = extract_counts(img)
    print('input array: \n', img)
    print('label counts: ', out)

You should get:

input array: 
 [[1. 1.]
 [1. 1.]]
label counts:  {1.0: 4}
input array: 
 [[1. 0. 0.]
 [0. 1. 0.]
 [0. 0. 1.]]
label counts:  {0.0: 6, 1.0: 3}
input array: 
 [[4 4 0]
 [2 4 3]
 [2 3 1]]
label counts:  {0: 1, 1: 1, 2: 2, 3: 2, 4: 3}

How to swap String characters in Java?

Here's a solution with a StringBuilder. It supports padding resulting strings with uneven string length with a padding character. As you've guessed this method is made for hexadecimal-nibble-swapping.

 * Swaps every character at position i with the character at position i + 1 in the given
 * string.
public static String swapCharacters(final String value, final boolean padding)
   if ( value == null )
      return null;

   final StringBuilder stringBuilder = new StringBuilder();
   int posA = 0;
   int posB = 1;
   final char padChar = 'F';

   // swap characters
   while ( posA < value.length() && posB < value.length() )
      stringBuilder.append( value.charAt( posB ) ).append( value.charAt( posA ) );
      posA += 2;
      posB += 2;

   // if resulting string is still smaller than original string we missed the last
   // character
   if ( stringBuilder.length() < value.length() )
      stringBuilder.append( value.charAt( posA ) );

   // add the padding character for uneven strings
   if ( padding && value.length() % 2 != 0 )
      stringBuilder.append( padChar );

   return stringBuilder.toString();

How do you cache an image in Javascript

Once an image has been loaded in any way into the browser, it will be in the browser cache and will load much faster the next time it is used whether that use is in the current page or in any other page as long as the image is used before it expires from the browser cache.

So, to precache images, all you have to do is load them into the browser. If you want to precache a bunch of images, it's probably best to do it with javascript as it generally won't hold up the page load when done from javascript. You can do that like this:

function preloadImages(array) {
    if (!preloadImages.list) {
        preloadImages.list = [];
    var list = preloadImages.list;
    for (var i = 0; i < array.length; i++) {
        var img = new Image();
        img.onload = function() {
            var index = list.indexOf(this);
            if (index !== -1) {
                // remove image from the array once it's loaded
                // for memory consumption reasons
                list.splice(index, 1);
        img.src = array[i];

preloadImages(["url1.jpg", "url2.jpg", "url3.jpg"]);

This function can be called as many times as you want and each time, it will just add more images to the precache.

Once images have been preloaded like this via javascript, the browser will have them in its cache and you can just refer to the normal URLs in other places (in your web pages) and the browser will fetch that URL from its cache rather than over the network.

Eventually over time, the browser cache may fill up and toss the oldest things that haven't been used in awhile. So eventually, the images will get flushed out of the cache, but they should stay there for awhile (depending upon how large the cache is and how much other browsing is done). Everytime the images are actually preloaded again or used in a web page, it refreshes their position in the browser cache automatically so they are less likely to get flushed out of the cache.

The browser cache is cross-page so it works for any page loaded into the browser. So you can precache in one place in your site and the browser cache will then work for all the other pages on your site.

When precaching as above, the images are loaded asynchronously so they will not block the loading or display of your page. But, if your page has lots of images of its own, these precache images can compete for bandwidth or connections with the images that are displayed in your page. Normally, this isn't a noticeable issue, but on a slow connection, this precaching could slow down the loading of the main page. If it was OK for preload images to be loaded last, then you could use a version of the function that would wait to start the preloading until after all other page resources were already loaded.

function preloadImages(array, waitForOtherResources, timeout) {
    var loaded = false, list = preloadImages.list, imgs = array.slice(0), t = timeout || 15*1000, timer;
    if (!preloadImages.list) {
        preloadImages.list = [];
    if (!waitForOtherResources || document.readyState === 'complete') {
    } else {
        window.addEventListener("load", function() {
        // in case window.addEventListener doesn't get called (sometimes some resource gets stuck)
        // then preload the images anyway after some timeout time
        timer = setTimeout(loadNow, t);

    function loadNow() {
        if (!loaded) {
            loaded = true;
            for (var i = 0; i < imgs.length; i++) {
                var img = new Image();
                img.onload = img.onerror = img.onabort = function() {
                    var index = list.indexOf(this);
                    if (index !== -1) {
                        // remove image from the array once it's loaded
                        // for memory consumption reasons
                        list.splice(index, 1);
                img.src = imgs[i];

preloadImages(["url1.jpg", "url2.jpg", "url3.jpg"], true);
preloadImages(["url99.jpg", "url98.jpg"], true);

Update data on a page without refreshing

I think you would like to learn ajax first, try this: Ajax Tutorial

If you want to know how ajax works, it is not a good way to use jQuery directly. I support to learn the native way to send a ajax request to the server, see something about XMLHttpRequest:

var xhr = new XMLHttpReuqest();"GET", "");

xhr.onreadystatechange = handler; // do something here...

Printing without newline (print 'a',) prints a space, how to remove?


It's pretty long time ago

Now, In python 3.x it will be pretty easy


for i in range(20):
      print('a',end='') # here end variable will clarify what you want in 
                        # end of the code



More about print() function




you can print multiple values using commas

sep = '-'

3 values will be separated by '-' character

you can use any character instead of that even string like sep='@' or sep='good'


by default print function put '\n' charater at the end of output

but you can use any character or string by changing end variale value

like end='$' or end='.' or end='Hello'


this is a default value, system standard output

using this argument you can create a output file stream like

print("I am a Programmer", file=open("output.txt", "w"))

by this code you will create a file named output.txt where your output I am a Programmer will be stored

flush = False

It's a default value using flush=True you can forcibly flush the stream

Can't append <script> element

Append script to body:

$(document).ready(function() {
    $("<script>", {  src : "bootstrap.min.js",  type : "text/javascript" }).appendTo("body");

How to get JSON objects value if its name contains dots?

Just to make use of updated solution try using lodash utility

Starting the week on Monday with isoWeekday()

try using begin.startOf('isoWeek'); instead of begin.startOf('week');

How can I convert JSON to a HashMap using Gson?

Here you go:

import java.lang.reflect.Type;

Type type = new TypeToken<Map<String, String>>(){}.getType();
Map<String, String> myMap = gson.fromJson("{'k1':'apple','k2':'orange'}", type);

PLS-00428: an INTO clause is expected in this SELECT statement

In PLSQL block, columns of select statements must be assigned to variables, which is not the case in SQL statements.

The second BEGIN's SQL statement doesn't have INTO clause and that caused the error.

   DSC           VARCHAR (512);
    WHERE PART_NUM = 'S0146404';

             || ','
             || RTRIM (PLANID.DESC_TEXT)
             || ','
             || CASE
                   WHEN PLANID.HIGH = 'TEST123'
                         WHEN TO_DATE (PROD.START_DATE) + 30 > SYSDATE
             || ','
             || 'GB'
             || ','
        INTO DSC
                ON PROD.PART_NUM = PLANID.VAL
                ON PROD.PROD_ID = PROD.ROW_ID
                ON VIS.PROD_ID = VISPROD.ROW_ID
       WHERE     PLANID.TYPE = 'Test Plan'
             AND PLANID.ACTIVE_FLG = 'Y'
             AND PROD.STATUS_CD = 'Active'


How do I use InputFilter to limit characters in an EditText in Android?

First add into strings.xml:

<string name="vin_code_mask">0123456789abcdefghjklmnprstuvwxyz</string>



Code in Kotlin:

edit_text.filters += InputFilter { source, start, end, _, _, _ ->
    val mask = getString(R.string.vin_code_mask)
    for (i in start until end) {
        if (!mask.contains(source[i])) {
            return@InputFilter ""

Strange, but it works weirdly on emulator's soft keyboard.

Warning! The following code will filter all letters and other symbols except digits for software keyboards. Only digital keyboard will appear on smartphones.

edit_text.keyListener = DigitsKeyListener.getInstance(context.getString(R.string.vin_code_mask))

I also usually set maxLength, filters, inputType.

To show a new Form on click of a button in C#

Try this:

private void Button1_Click(Object sender, EventArgs e ) 
   var myForm = new Form1();

How do you add a JToken to an JObject?

I think you're getting confused about what can hold what in JSON.Net.

  • A JToken is a generic representation of a JSON value of any kind. It could be a string, object, array, property, etc.
  • A JProperty is a single JToken value paired with a name. It can only be added to a JObject, and its value cannot be another JProperty.
  • A JObject is a collection of JProperties. It cannot hold any other kind of JToken directly.

In your code, you are attempting to add a JObject (the one containing the "banana" data) to a JProperty ("orange") which already has a value (a JObject containing {"colour":"orange","size":"large"}). As you saw, this will result in an error.

What you really want to do is add a JProperty called "banana" to the JObject which contains the other fruit JProperties. Here is the revised code:

JObject foodJsonObj = JObject.Parse(jsonText);
JObject fruits = foodJsonObj["food"]["fruit"] as JObject;
fruits.Add("banana", JObject.Parse(@"{""colour"":""yellow"",""size"":""medium""}"));

Get all validation errors from Angular 2 FormGroup

I met the same problem and for finding all validation errors and displaying them, I wrote next method:

getFormValidationErrors() {
  Object.keys(this.productForm.controls).forEach(key => {

  const controlErrors: ValidationErrors = this.productForm.get(key).errors;
  if (controlErrors != null) {
        Object.keys(controlErrors).forEach(keyError => {
          console.log('Key control: ' + key + ', keyError: ' + keyError + ', err value: ', controlErrors[keyError]);

Form name productForm should be changed to yours.

It works in next way: we get all our controls from form in format {[p: string]: AbstractControl} and iterate by each error key, for get details of error. It skips null error values.

It also can be changed for displaying validation errors on the template view, just replace console.log(..) to what you need.

Postgresql - unable to drop database because of some auto connections to DB

REVOKE CONNECT will not prevent the connections from the db owner or superuser. So if you don't want anyone to connect the db, follow command may be useful.

alter database pilot allow_connections = off;

Then use:

SELECT pg_terminate_backend(pid)
FROM pg_stat_activity
WHERE datname = 'pilot';

Using print statements only to debug

I don't know about others, but I was used to define a "global constant" (DEBUG) and then a global function (debug(msg)) that would print msg only if DEBUG == True.

Then I write my debug statements like:

debug('My value: %d' % value)

...then I pick up unit testing and never did this again! :)

Check if bash variable equals 0

Specifically: ((depth)). By example, the following prints 1.

declare -i x=0
((x)) && echo $x

((x)) && echo $x

If '<selector>' is an Angular component, then verify that it is part of this module

In my case I had a component in a Shared module.

The component was loading and worked well but typescript was highlighting the html tag with red line and showed this error message.

Inside this component, I noticed I didn't import a rxjs operator.

import {map} from 'rxjs/operators';

When I added this import the error message disappeared.

Check all imports inside the component.

Hope it helps someone.

What does ON [PRIMARY] mean?

ON [PRIMARY] will create the structures on the "Primary" filegroup. In this case the primary key index and the table will be placed on the "Primary" filegroup within the database.

PHP: How to get referrer URL?

$_SERVER['HTTP_REFERER'] will give you the referrer page's URL if there exists any. If users use a bookmark or directly visit your site by manually typing in the URL, http_referer will be empty. Also if the users are posting to your page programatically (CURL) then they're not obliged to set the http_referer as well. You're missing all _, is that a typo?

Laravel 4: Redirect to a given url

Yes, it's

use Illuminate\Support\Facades\Redirect;

return Redirect::to('');

Check the documentation.

Update: Redirect::away('url') (For external link, Laravel Version 4.19):

public function away($path, $status = 302, $headers = array())
    return $this->createRedirect($path, $status, $headers);

Apache Spark: map vs mapPartitions?


Map transformation.

The map works on a single Row at a time.

Map returns after each input Row.

The map doesn’t hold the output result in Memory.

Map no way to figure out then to end the service.

// map example

val dfList = (1 to 100) toList

val df = dfList.toDF()

val dfInt = => x.getInt(0)+2)



MapPartition transformation.

MapPartition works on a partition at a time.

MapPartition returns after processing all the rows in the partition.

MapPartition output is retained in memory, as it can return after processing all the rows in a particular partition.

MapPartition service can be shut down before returning.

// MapPartition example

Val dfList = (1 to 100) toList

Val df = dfList.toDF()

Val df1 = df.repartition(4).rdd.mapPartition((int) => Iterator(itr.length))



For more details, please refer to the Spark map vs mapPartitions transformation article.

Hope this is helpful!

Colouring plot by factor in R

The command palette tells you the colours and their order when col = somefactor. It can also be used to set the colours as well.

[1] "black"   "red"     "green3"  "blue"    "cyan"    "magenta" "yellow"  "gray"   

In order to see that in your graph you could use a legend.

legend('topright', legend = levels(iris$Species), col = 1:3, cex = 0.8, pch = 1)

You'll notice that I only specified the new colours with 3 numbers. This will work like using a factor. I could have used the factor originally used to colour the points as well. This would make everything logically flow together... but I just wanted to show you can use a variety of things.

You could also be specific about the colours. Try ?rainbow for starters and go from there. You can specify your own or have R do it for you. As long as you use the same method for each you're OK.

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


Absolute path of a single file:

stat -c %n "$PWD"/foo/bar

How do I use a pipe to redirect the output of one command to the input of another?

Not sure if you are coding these programs, but this is a simple example of how you'd do it.


#include <stdio.h>
int main (int argc, char * argv[] ) {
    printf("%s", argv[1]); 
    return 0;


#include <cstdio>
#include <regex>
#include <iostream>
using namespace std;
int main (int argc, char * argv[] ) {
    char input[200];
    string s(input)
    smatch m;
    string reg_exp(argv[1]);
    regex e(reg_exp);
    while (regex_search (s,m,e)) {
      for (auto x:m) cout << x << " ";
      cout << endl;
      s = m.suffix().str();
    return 0;

Compile both then run program1.exe "this subject has a submarine as a subsequence" | rgx.exe "\b(sub)([^ ]*)"

The | operator simply redirects the output of program1's printf operation from the stdout stream to the stdin stream whereby it's sitting there waiting for rgx.exe to pick up.

x86 Assembly on a Mac

Don't forget that unlike Windows, all Unix based system need to have the source before destination unlike Windows

On Windows its:

mov $source , %destination

but on the Mac its the other way around.

Git fatal: protocol 'https' is not supported

There is something fishy going on. Probably a github bug that is not consistent (A/B testing?)

I am on windows10, using firefox. I have just copied a checkout URL and got an extra character. But only the first time. A second time it wasn't there. I had to look at my history file to see it!

here is my history:

git clone --recursive
git clone --recursive
git clone --recursive
git clone --recursive

the history command doesn't show the extra char. Just like it wasn't rendered when i was copy-pasting it into the terminal. You can see how i tried to remove the 's' and then the entire protocol? I was only triggered to investigate further when the backspace key moved one less character than i was expecting!

I saved my shell history file onto a machine with an hex editor and:

00000000  xx xx xx xx xx xx xx 0a  67 69 74 20 63 6c 6f 6e  |xxxxxxx.git clon|
00000010  65 20 2d 2d 72 65 63 75  72 73 69 76 65 20 c2 96  |e --recursive ..|
00000020  68 74 74 70 73 3a 2f 2f  67 69 74 68 75 62 2e 63  |https://github.c|
00000030  6f 6d 2f 61 6d 7a 65 72  61 74 75 6c 2f 68 61 6c  |om/amzeratul/hal|
00000040  6c 65 79 2d 74 65 6d 70  6c 61 74 65 0a 67 69 74  |ley-template.git|
00000050  20 2d 2d 68 65 6c 70 0a  67 69 74 20 75 70 64 61  | --help.git upda|
00000060  74 65 2d 67 69 74 2d 66  6f 72 2d 77 69 6e 64 6f  |te-git-for-windo|
00000070  77 73 0a 67 69 74 20 63  6c 6f 6e 65 20 2d 2d 72  |ws.git clone --r|
00000080  65 63 75 72 73 69 76 65  20 c2 96 68 74 74 70 73  |ecursive ..https|
00000090  3a 2f 2f 67 69 74 68 75  62 2e 63 6f 6d 2f 61 6d  |://|
000000a0  7a 65 72 61 74 75 6c 2f  68 61 6c 6c 65 79 2d 74  |zeratul/halley-t|
000000b0  65 6d 70 6c 61 74 65 0a  63 75 72 6c 20 2d 2d 76  |emplate.curl --v|
000000c0  65 72 73 69 6f 6e 0a 63  64 20 63 6f 64 65 0a 67  | code.g|
000000d0  69 74 20 63 6c 6f 6e 65  20 2d 2d 72 65 63 75 72  |it clone --recur|
000000e0  73 69 76 65 20 c2 96 68  74 74 70 73 3a 2f 2f 67  |sive ..https://g|
000000f0  69 74 68 75 62 2e 63 6f  6d 2f 61 6d 7a 65 72 61  ||
00000100  74 75 6c 2f 68 61 6c 6c  65 79 2d 74 65 6d 70 6c  |tul/halley-templ|
00000110  61 74 65 0a 67 69 74 20  63 6c 6f 6e 65 20 2d 2d  |ate.git clone --|
00000120  72 65 63 75 72 73 69 76  65 20 c2 96 68 74 74 70  |recursive ..http|
00000130  3a 2f 2f 67 69 74 68 75  62 2e 63 6f 6d 2f 61 6d  |://|
00000140  7a 65 72 61 74 75 6c 2f  68 61 6c 6c 65 79 2d 74  |zeratul/halley-t|
00000150  65 6d 70 6c 61 74 65 0a  67 69 74 20 63 6c 6f 6e  |emplate.git clon|
00000160  65 20 2d 2d 72 65 63 75  72 73 69 76 65 20 67 69  |e --recursive gi|
00000170  74 68 75 62 2e 63 6f 6d  2f 61 6d 7a 65 72 61 74  ||
00000180  75 6c 2f 68 61 6c 6c 65  79 2d 74 65 6d 70 6c 61  |ul/halley-templa|
00000190  74 65 0a 67 69 74 20 63  6c 6f 6e 65 20 2d 2d 72  |te.git clone --r|
000001a0  65 63 75 72 73 69 76 65  20 68 74 74 70 73 3a 2f  |ecursive https:/|
000001b0  2f 67 69 74 68 75 62 2e  63 6f 6d 2f 61 6d 7a 65  |/|
000001c0  72 61 74 75 6c 2f 68 61  6c 6c 65 79 2d 74 65 6d  |ratul/halley-tem|
000001d0  70 6c 61 74 65 0a                                 |plate.|

There i a c2 96 char inserted before the url. No idea what that is. Is it not extended ASCII (where it would be –) and it was hidden from almost every place i pasted while it was on the clipboard. The closest i've found with this hex value would be but i didn't see the utf prefix anywhere (again, might have been lost)

This all might be misleading as I lost the page/clipboard and am working exclusively from the saved shell history file, which might very well be missing data from the original bug/malicious injection.

What's the difference between setWebViewClient vs. setWebChromeClient?

I feel this question need a bit more details. My answer is inspired from the Android Programming, The Big Nerd Ranch Guide (2nd edition).

By default, JavaScript is off in WebView. You do not always need to have it on, but for some apps, might do require it.

Loading the URL has to be done after configuring the WebView, so you do that last. Before that, you turn JavaScript on by calling getSettings() to get an instance of WebSettings and calling WebSettings.setJavaScriptEnabled(true). WebSettings is the first of the three ways you can modify your WebView. It has various properties you can set, like the user agent string and text size.

After that, you configure your WebViewClient. WebViewClient is an event interface. By providing your own implementation of WebViewClient, you can respond to rendering events. For example, you could detect when the renderer starts loading an image from a particular URL or decide whether to resubmit a POST request to the server.

WebViewClient has many methods you can override, most of which you will not deal with. However, you do need to replace the default WebViewClient’s implementation of shouldOverrideUrlLoading(WebView, String). This method determines what will happen when a new URL is loaded in the WebView, like by pressing a link. If you return true, you are saying, “Do not handle this URL, I am handling it myself.” If you return false, you are saying, “Go ahead and load this URL, WebView, I’m not doing anything with it.”

The default implementation fires an implicit intent with the URL, just like you did earlier. Now, though, this would be a severe problem. The first thing some Web Applications does is redirect you to the mobile version of the website. With the default WebViewClient, that means that you are immediately sent to the user’s default web browser. This is just what you are trying to avoid. The fix is simple – just override the default implementation and return false.

Use WebChromeClient to spruce things up Since you are taking the time to create your own WebView, let’s spruce it up a bit by adding a progress bar and updating the toolbar’s subtitle with the title of the loaded page.

To hook up the ProgressBar, you will use the second callback on WebView: WebChromeClient.

WebViewClient is an interface for responding to rendering events; WebChromeClient is an event interface for reacting to events that should change elements of chrome around the browser. This includes JavaScript alerts, favicons, and of course updates for loading progress and the title of the current page.

Hook it up in onCreateView(…). Using WebChromeClient to spruce things up Progress updates and title updates each have their own callback method, onProgressChanged(WebView, int) and onReceivedTitle(WebView, String). The progress you receive from onProgressChanged(WebView, int) is an integer from 0 to 100. If it is 100, you know that the page is done loading, so you hide the ProgressBar by setting its visibility to View.GONE.

Disclaimer: This information was taken from Android Programming: The Big Nerd Ranch Guide with permission from the authors. For more information on this book or to purchase a copy, please visit

Get user info via Google API

There are 3 steps that needs to be run.

  1. Register your app's client id from Google API console
  2. Ask your end user to give consent using this api
  3. Use google's oauth2 api as described at using the token obtained in step 2. (Though still I could not find how to fill "fields" parameter properly).

It is very interesting that this simplest usage is not clearly described anywhere. And i believe there is a danger, you should pay attention to the verified_emailparameter coming in the response. Because if I am not wrong it may yield fake emails to register your application. (This is just my interpretation, has a fair chance that I may be wrong!)

I find facebook's OAuth mechanics much much clearly described.

You are trying to add a non-nullable field 'new_field' to userprofile without a default

I was early in my development cycle, so this may not work for everyone (but I don't see why it wouldn't).

I added blank=True, null=True to the columns where I was getting the error. Then I ran the python makemigrations command.

Immediately after running this command (and before running python migrate), I removed the blank=True, null=True from all the columns. Then I ran python makemigrations again. I was given an option to just change the columns myself, which I selected.

Then I ran python migrate and everything worked well!

How to check if element exists using a lambda expression?

Try to use anyMatch of Lambda Expression. It is much better approach.

 boolean idExists = tabPane.getTabs().stream()
            .anyMatch(t -> t.getId().equals(idToCheck));

finding the type of an element using jQuery

The following will return true if the element is an input:


or you can use the following to get the name of the tag:


iOS: UIButton resize according to text length

To accomplish this using autolayout, try setting a variable width constraint:

Width Constraint

You may also need to adjust your Content Hugging Priority and Content Compression Resistance Priority to get the results you need.

UILabel is completely automatically self-sizing:

This UILabel is simply set to be centered on the screen (two constraints only, horizontal/vertical):

It changes widths totally automatically:

You do not need to set any width or height - it's totally automatic.

enter image description here

enter image description here

Notice the small yellow squares are simply attached ("spacing" of zero). They automatically move as the UILabel resizes.

Adding a ">=" constraint sets a minimum width for the UILabel:

enter image description here

Test for multiple cases in a switch, like an OR (||)

You can use fall-through:

switch (pageid)
    case "listing-page":
    case "home-page":
    case "details-page":

Angular 2 router.navigate

import { ActivatedRoute } from '@angular/router';_x000D_
export class ClassName {_x000D_
  private router = ActivatedRoute;_x000D_
    constructor(r: ActivatedRoute) {_x000D_
        this.router =r;_x000D_
onSuccess() {_x000D_
         {queryParams: {email: loginEmail, code: userCode}});_x000D_
Get this values:_x000D_
ngOnInit() {_x000D_
        .subscribe(params => {_x000D_
            let code = params['code'];_x000D_
            let userEmail = params['email'];_x000D_


How to add fonts to create-react-app based projects?

You can use the Web API FontFace constructor (also Typescript) without need of CSS:

export async function loadFont(fontFamily: string, url: string): Promise<void> {
    const font = new FontFace(fontFamily, `local(${fontFamily}), url(${url})`);
    // wait for font to be loaded
    await font.load();
    // add font to document
    // enable font with CSS class
import ComicSans from "./assets/fonts/ComicSans.ttf";

loadFont("Comic Sans ", ComicSans).catch((e) => {

Declare a file font.ts with your modules (TS only):

declare module "*.ttf";
declare module "*.woff";
declare module "*.woff2";

If TS cannot find FontFace type as its still officially WIP, add this declaration to your project. It will work in your browser, except for IE.

SQL Server 2008 Windows Auth Login Error: The login is from an untrusted domain

Okay, completely out there answer from me. I was getting this error from a development environment hosted on VM VirtualBox. Three servers; SharePoint, SQL DB and Domain Controller. The SharePoint server couldn't connect to the configuration database. I could still connect via ODBC for Sql authentication using SA account but not Windows authentication. But that user would happily log into SSMS on the sql server itself. I got a better error message from ODBC too and also by checking the failed login messages on sql server:

select text from sys.messages where message_id = '18452' and language_id = 1033

Can't take credit for this because I asked one of our Enterprise Systems Administrators for help and he diagnosed it in about 5 minutes of looking at a few screen shots I sent him. Problem was that the Domain Controller’s clock was set incorrectly! Couldn't believe it. The servers are setup for Host Only networking so don't have internet to sync the clock with. That also explains why rolling back to an earlier snapshot when I know the system was working didn't solve the problem.

Edit: Installing the Guest Additions on the server syncs the guest clock with the host.

Delete all data rows from an Excel table (apart from the first)

This is how I clear the data:

Sub Macro3()
    With Sheet1.ListObjects("Table1")
        If Not .DataBodyRange Is Nothing Then
        End If
    End With
End Sub

ReactJS - How to use comments?

To summarize, JSX doesn't support comments, either html-like or js-like:

    /* This will be rendered as text */
    // as well as this
    <!-- While this will cause compilation failure -->

and the only way to add comments "in" JSX is actually to escape into JS and comment in there:

    {/* This won't be rendered */}
    {// just be sure that your closing bracket is out of comment

if you don't want to make some nonsense like

<div style={{display:'none'}}>
    actually, there are other stupid ways to add "comments"
    but cluttering your DOM is not a good idea

Finally, if you do want to create a comment node via React, you have to go much fancier, check out this answer.

How do I check two or more conditions in one <c:if>?

This look like a duplicate of JSTL conditional check.

The error is having the && outside the expression. Instead use

<c:if test="${ISAJAX == 0 && ISDATE == 0}">

Difference between opening a file in binary vs text

The most important difference to be aware of is that with a stream opened in text mode you get newline translation on non-*nix systems (it's also used for network communications, but this isn't supported by the standard library). In *nix newline is just ASCII linefeed, \n, both for internal and external representation of text. In Windows the external representation often uses a carriage return + linefeed pair, "CRLF" (ASCII codes 13 and 10), which is converted to a single \n on input, and conversely on output.

From the C99 standard (the N869 draft document), §7.19.2/2,

A text stream is an ordered sequence of characters composed into lines, each line consisting of zero or more characters plus a terminating new-line character. Whether the last line requires a terminating new-line character is implementation-defined. Characters may have to be added, altered, or deleted on input and output to conform to differing conventions for representing text in the host environment. Thus, there need not be a one- to-one correspondence between the characters in a stream and those in the external representation. Data read in from a text stream will necessarily compare equal to the data that were earlier written out to that stream only if: the data consist only of printing characters and the control characters horizontal tab and new-line; no new-line character is immediately preceded by space characters; and the last character is a new-line character. Whether space characters that are written out immediately before a new-line character appear when read in is implementation-defined.

And in §7.19.3/2

Binary files are not truncated, except as defined in Whether a write on a text stream causes the associated file to be truncated beyond that point is implementation- defined.

About use of fseek, in §

For a text stream, either offset shall be zero, or offset shall be a value returned by an earlier successful call to the ftell function on a stream associated with the same file and whence shall be SEEK_SET.

About use of ftell, in §

The ftell function obtains the current value of the file position indicator for the stream pointed to by stream. For a binary stream, the value is the number of characters from the beginning of the file. For a text stream, its file position indicator contains unspecified information, usable by the fseek function for returning the file position indicator for the stream to its position at the time of the ftell call; the difference between two such return values is not necessarily a meaningful measure of the number of characters written or read.

I think that’s the most important, but there are some more details.

Checking Maven Version

Type the command mvn -version directly in your maven directory, you probably haven't added it to your PATH. Here are explained details of how to add maven to your PATH variable (I guess you use Windows because you are talking about CMD).

Instagram: Share photo from webpage

Uploading on Instagram is possible. Their API provides a media upload endpoint, even if it's not documented.


Check this code for example

How to convert an object to a byte array in C#

I found another way to convert an object to a byte[], here is my solution:

IEnumerable en = (IEnumerable) myObject;
byte[] myBytes = en.OfType<byte>().ToArray();


Change Row background color based on cell value DataTable

This is how managed to change my data table row background (DataTables 1.10.19)

    "processing": true,
    "serverSide": true,
        "dataType": "json",
        "type": "POST",
        "url": mainUrl+"/getMember",
    "columns": [
        { "data": "id" },
        { "data": "name" },
        { "data": "email" },
        { "data": "phone" },
        { "data": "country_id" },
        { "data": "created_at" },
        { "data": "action" },
    "fnRowCallback": function( nRow, aData, iDisplayIndex, iDisplayIndexFull ) {
            case 1:
                $('td', nRow).css('background-color', '#dacfcf')

You can use fnRowCallback method function to change the background.

Very Simple, Very Smooth, JavaScript Marquee

I just created a simple jQuery plugin for that. Try it ;)

Log all queries in mysql

OS / mysql version:

$ uname -a
Darwin Raphaels-MacBook-Pro.local 15.6.0 Darwin Kernel Version 15.6.0: Thu Jun 21 20:07:40 PDT 2018; root:xnu-3248.73.11~1/RELEASE_X86_64 x86_64

$ mysql --version
/usr/local/mysql/bin/mysql  Ver 14.14 Distrib 5.6.23, for osx10.8 (x86_64) using  EditLine wrapper

Adding logging (example, I don't think /var/log/... is the best path on Mac OS but that worked:

sudo vi ./usr/local/mysql-5.6.23-osx10.8-x86_64/my.cnf

general_log = on

Restarted Mysql


$ sudo tail -f /var/log/mysql/mysqld_general.log
181210  9:41:04    21 Connect   root@localhost on employees
           21 Query /* mysql-connector-java-5.1.47 ( Revision: fe1903b1ecb4a96a917f7ed3190d80c049b1de29 ) */SELECT  @@session.auto_increment_increment AS auto_increment_increment, @@character_set_client AS character_set_client, @@character_set_connection AS character_set_connection, @@character_set_results AS character_set_results, @@character_set_server AS character_set_server, @@collation_server AS collation_server, @@collation_connection AS collation_connection, @@init_connect AS init_connect, @@interactive_timeout AS interactive_timeout, @@license AS license, @@lower_case_table_names AS lower_case_table_names, @@max_allowed_packet AS max_allowed_packet, @@net_buffer_length AS net_buffer_length, @@net_write_timeout AS net_write_timeout, @@query_cache_size AS query_cache_size, @@query_cache_type AS query_cache_type, @@sql_mode AS sql_mode, @@system_time_zone AS system_time_zone, @@time_zone AS time_zone, @@tx_isolation AS transaction_isolation, @@wait_timeout AS wait_timeout
           21 Query SET NAMES latin1
           21 Query SET character_set_results = NULL
           21 Query SET autocommit=1
           21 Query SELECT USER()
           21 Query SELECT USER()
181210  9:41:10    21 Query show tables
181210  9:41:25    21 Query select count(*) from current_dept_emp

Measure string size in Bytes in php

Further to PhoneixS answer to get the correct length of string in bytes - Since mb_strlen() is slower than strlen(), for the best performance one can check "mbstring.func_overload" ini setting so that mb_strlen() is used only when it is really required:

$content_length = ini_get('mbstring.func_overload') ? mb_strlen($content , '8bit') : strlen($content);

Python exit commands - why so many and when should each be used?

Different Means of Exiting


  • Exit the process without calling the cleanup handlers.


  • a clean exit without any errors / problems.


  • There was some issue / error / problem and that is why the program is exiting.


  • When the system and python shuts down; it means less memory is being used after the program is run.


  • Closes the python file.


Basically they all do the same thing, however, it also depends on what you are doing it for.

I don't think you left anything out and I would recommend getting used to quit() or exit().

You would use sys.exit() and os._exit() mainly if you are using big files or are using python to control terminal.

Otherwise mainly use exit() or quit().

IntelliJ shortcut to show a popup of methods in a class that can be searched

I prefer to use the Structure view. To open it, use the menu: View/Tools Window/Structure. The hotkey on Windows is Alt+7

Char array declaration and initialization in C

Yes, this is a kind of inconsistency in the language.

The "=" in myarray = "abc"; is assignment (which won't work as the array is basically a kind of constant pointer), whereas in char myarray[4] = "abc"; it's an initialization of the array. There's no way for "late initialization".

You should just remember this rule.

How to silence output in a Bash script?

If you want STDOUT and STDERR both [everything], then the simplest way is:

myprogram >& sample.s

then run it like ./script, and you will get no output to your terminal. :)

the ">&" means STDERR and STDOUT. the & also works the same way with a pipe: ./script |& sed that will send everything to sed

MySQL error 1449: The user specified as a definer does not exist

I have tried the above methods, but feels like repetitive action when creating the view. I got the same issue while updating the views of the imported database.

You can simply overcome the issue in LOCAL by simply creating the User with the create privilege.

C#, Looping through dataset and show each record from a dataset column

DateTime TaskStart = DateTime.Parse(dr["TaskStart"].ToString());

How do I format a String in an email so Outlook will print the line breaks?

Try \r\c instead of \n.

EDIT: I think @Robert Wilkinson had it right. \r\n. Memory just isn't what it used to be.

PHP Fatal error: Using $this when not in object context

When you call the function in a static context, $this simply doesn't exist.

You would have to use this::xyz() instead.

To find out what context you're in when a function can be called both statically and in an object instance, a good approach is outlined in this question: How to tell whether I’m static or an object?

Reversing a string in C

That's a good question ant2009. You can use a standalone function to reverse the string. The code is...

#include <stdio.h>

int main( void );
int strlen( char __str );

int main() {
    char *str[ MAX_CHARACTERS ];
    char *new_string[ MAX_CHARACTERS ];
    int i, j;

    printf( "enter string: " );
    gets( *str );

    for( i = 0; j = ( strlen( *str ) - 1 ); i < strlen( *str ), j > -1; i++, j-- ) {
        *str[ i ] = *new_string[ j ];
    printf( "Reverse string is: %s", *new_string" );
    return ( 0 );

int strlen( char __str[] ) {
    int count;
    for( int i = 0; __str[ i ] != '\0'; i++ ) {
    return ( count );

What is href="#" and why is it used?

Unfortunately, the most common use of <a href="#"> is by lazy programmers who want clickable non-hyperlink javascript-coded elements that behave like anchors, but they can't be arsed to add cursor: pointer; or :hover styles to a class for their non-hyperlink elements, and are additionally too lazy to set href to javascript:void(0);.

The problem with this is that one <a href="#" onclick="some_function();"> or another inevitably ends up with a javascript error, and an anchor with an onclick javascript error always ends up following its href. Normally this ends up being an annoying jump to the top of the page, but in the case of sites using <base>, <a href="#"> is handled as <a href="[base href]/#">, resulting in an unexpected navigation. If any logable errors are being generated, you won't see them in the latter case unless you enable persistent logs.

If an anchor element is used as a non-anchor it should have its href set to javascript:void(0); for the sake of graceful degradation.

I just wasted two days debugging a random unexpected page redirect that should have simply refreshed the page, and finally tracked it down to a function raising the click event of an <a href="#">. Replacing the # with javascript:void(0); fixed it.

The first thing I'm doing Monday is purging the project of all instances of <a href="#">.

What does the Ellipsis object do?

As of Python 3.5 and PEP484, the literal ellipsis is used to denote certain types to a static type checker when using the typing module.

Example 1:

Arbitrary-length homogeneous tuples can be expressed using one type and ellipsis, for example Tuple[int, ...]

Example 2:

It is possible to declare the return type of a callable without specifying the call signature by substituting a literal ellipsis (three dots) for the list of arguments:

def partial(func: Callable[..., str], *args) -> Callable[..., str]:
    # Body

Adjusting the Xcode iPhone simulator scale and size

In Xcode 9 there is a new "Actual Size" option. In the Simulator to the Window menu and choose Scale > Actual Size to trigger it. This takes into account your current screen resolution to ensure the on-screen device matches the physical dimensions of a real device.

How to read/write arbitrary bits in C/C++

just use this and feelfree:

#define BitVal(data,y) ( (data>>y) & 1)      /** Return Data.Y value   **/
#define SetBit(data,y)    data |= (1 << y)    /** Set Data.Y   to 1    **/
#define ClearBit(data,y)  data &= ~(1 << y)   /** Clear Data.Y to 0    **/
#define TogleBit(data,y)     (data ^=BitVal(y))     /** Togle Data.Y  value  **/
#define Togle(data)   (data =~data )         /** Togle Data value     **/

for example:

uint8_t number = 0x05; //0b00000101
uint8_t bit_2 = BitVal(number,2); // bit_2 = 1
uint8_t bit_1 = BitVal(number,1); // bit_1 = 0

SetBit(number,1); // number =  0x07 => 0b00000111
ClearBit(number,2); // number =0x03 => 0b0000011

syntaxerror: "unexpected character after line continuation character in python" math

The division operator is / rather than \.

Also, the backslash has a special meaning inside a Python string. Either escape it with another backslash:

"\\ 1.5 = "`

or use a raw string

r" \ 1.5 = "

Hide/Show Action Bar Option Menu Item for different fragments

This is one way of doing this:

add a "group" to your menu:

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="" >

         <item android:id="@+id/done_item"

then, add a

Menu menu;

variable to your activity and set it in your override of onCreateOptionsMenu:

public boolean onCreateOptionsMenu(Menu menu) { = menu;
    // inflate your menu here

After, add and use this function to your activity when you'd like to show/hide the menu:

public void showOverflowMenu(boolean showMenu){
    if(menu == null)
    menu.setGroupVisible(, showMenu);

I am not saying this is the best/only way, but it works well for me.

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

You can always take the CTE, (Common Tabular Expression), approach.

;WITH updateCTE AS
    WHERE ID = 101


How to use sed to extract substring

You should not parse XML using tools like sed, or awk. It's error-prone.

If input changes, and before name parameter you will get new-line character instead of space it will fail some day producing unexpected results.

If you are really sure, that your input will be always formated this way, you can use cut. It's faster than sed and awk:

cut -d'"' -f2 < input.txt

It will be better to first parse it, and extract only parameter name attribute:

xpath -q -e //@name input.txt | cut -d'"' -f2

To learn more about xpath, see this tutorial:

What is the best algorithm for overriding GetHashCode?

ValueTuple - Update for C# 7

As @cactuaroid mentions in the comments, a value tuple can be used. This saves a few keystrokes and more importantly executes purely on the stack (no Garbage):

(PropA, PropB, PropC, PropD).GetHashCode();

(Note: The original technique using anonymous types seems to create an object on the heap, i.e. garbage, since anonymous types are implemented as classes, though this might be optimized out by the compiler. It would be interesting to benchmark these options, but the tuple option should be superior.)

Anonymous Type (Original Answer)

Microsoft already provides a good generic HashCode generator: Just copy your property/field values to an anonymous type and hash it:

new { PropA, PropB, PropC, PropD }.GetHashCode();

This will work for any number of properties. It does not use boxing. It just uses the algorithm already implemented in the framework for anonymous types.

How can I throw CHECKED exceptions from inside Java 8 streams?

I wrote a library that extends the Stream API to allow you to throw checked exceptions. It uses Brian Goetz's trick.

Your code would become

public List<Class> getClasses() throws ClassNotFoundException {     
    Stream<String> classNames = 
        Stream.of("java.lang.Object", "java.lang.Integer", "java.lang.String");

    return ThrowingStream.of(classNames, ClassNotFoundException.class)

Create new user in MySQL and give it full access to one database

In case the host part is omitted it defaults to the wildcard symbol %, allowing all hosts.

CREATE USER 'service-api';

GRANT ALL PRIVILEGES ON the_db.* TO 'service-api' IDENTIFIED BY 'the_password'

SELECT * FROM mysql.user;
SHOW GRANTS FOR 'service-api'

Ordering by specific field value first

do this:

SELECT * FROM table ORDER BY column `name`+0 ASC

Appending the +0 will mean that:

0, 10, 11, 2, 3, 4

becomes :

0, 2, 3, 4, 10, 11

Invalid attempt to read when no data is present

You have to call dr.Read() before attempting to read any data. That method will return false if there is nothing to read.

Can a normal Class implement multiple interfaces?

It is true that a java class can implement multiple interfaces at the same time, but there is a catch here. If in a class, you are trying to implement two java interfaces, which contains methods with same signature but diffrent return type, in that case you will get compilation error.

interface One
    int m1();
interface Two
    float m1();
public class MyClass implements One, Two{
    int m1() {}
    float m1() {}
    public static void main(String... args) {


output : error: method m1() is already defined in class MyClass
    public float m1() {}
                 ^ error: MyClass is not abstract and does not override abstract method m1() in Two
public class MyClass implements One, Two{
       ^ error: m1() in MyClass cannot implement m1() in Two
    public int m1() {}
  return type int is not compatible with float
3 errors

Docker: How to delete all local Docker images

To simple clear everything do:

$ docker system prune --all

Everything means:

  • all stopped containers
  • all networks not used by at least one container
  • all images without at least one container associated to them
  • all build cache

How to dynamically add a style for text-align using jQuery

Is correct?

$( "#box" ).one( "click", function() {
  $( this ).css( "width", "+=200" );

error: use of deleted function

In the current C++0x standard you can explicitly disable default constructors with the delete syntax, e.g.

MyClass() = delete;

Gcc 4.6 is the first version to support this syntax, so maybe that is the problem...

How to position two elements side by side using CSS

You have two options, either float:left or display:inline-block.

Both methods have their caveats. It seems that display:inline-block is more common nowadays, as it avoids some of the issues of floating.

Read this article or this one for a more in detail discussion.

Disabling swap files creation in vim

create no vim swap file just for a particular file

autocmd bufenter  c:/aaa/Dropbox/TapNote/Todo.txt :set noswapfile

Change the encoding of a file in Visual Studio Code

Apart from the settings explained in the answer by @DarkNeuron:

"files.encoding": "any encoding"

you can also specify settings for a specific language like so:

"[language id]": {
  "files.encoding": "any encoding"

For example, I use this when I need to edit PowerShell files previously created with ISE (which are created in ANSI format):

"[powershell]": {
    "files.encoding": "windows1252"

You can get a list of identifiers of well-known languages here.

No Persistence provider for EntityManager named

Verify the peristent unit name

<persistence-unit name="com.myapp.model.jpa"
public static final String PERSISTENCE_UNIT_NAME = "com.myapp.model.jpa";

C++ "Access violation reading location" Error

Vertex *f=(findvertex(from));
if(!f) {
    cerr << "vertex not found" << endl;
    exit(1) // or return;

Because findVertex can return NULL if it can't find the vertex.

Otherwise this f->adj; is trying to do


Which causes access violation.

Multiple inheritance for an anonymous class

An anonymous class is extending or implementing while creating its object For example :

Interface in = new InterFace()



Here anonymous class is implementing Interface.

Class cl = new Class(){



here anonymous Class is extending a abstract Class.

QLabel: set color of text and background

This one is working perfect

QColorDialog *dialog = new QColorDialog(this);
QColor color=  dialog->getColor();
QVariant variant= color;
QString colcode = variant.toString();
ui->label->setStyleSheet("QLabel { background-color :"+colcode+" ; color : blue; }");

getColor() method returns the selected color. You can change label color using stylesheet

PHP: How to check if a date is today, yesterday or tomorrow

function get_when($date) {

    $current = strtotime(date('Y-m-d H:i'));

    $date_diff = $date - $current;
    $difference = round($date_diff/(60*60*24));

    if($difference >= 0) {
            return 'Today';
    } else if($difference == -1) {
            return 'Yesterday';
    } else if($difference == -2 || $difference == -3  || $difference == -4 || $difference == -5) {
            return date('l', $date);
    } else {
            return ('on ' . date('jS/m/y', $date));


get_when(date('Y-m-d H:i', strtotime($your_targeted_date)));

Android 6.0 Marshmallow. Cannot write to SD Card

Maybe you cannot use manifest class from generated code in your project. So, you can use manifest class from android sdk "android.Manifest.permission.WRITE_EXTERNAL_STORAGE". But in Marsmallow version have 2 permission must grant are WRITE and READ EXTERNAL STORAGE in storage category. See my program, my program will request permission until user choose yes and do something after permissions is granted.

            if (Build.VERSION.SDK_INT >= 23) {
                if (ContextCompat.checkSelfPermission(LoginActivity.this, android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
                        != PackageManager.PERMISSION_GRANTED || ContextCompat.checkSelfPermission(LoginActivity.this, android.Manifest.permission.READ_EXTERNAL_STORAGE)
                        != PackageManager.PERMISSION_GRANTED) {
                            new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE, android.Manifest.permission.READ_EXTERNAL_STORAGE},
                } else {
                    //do something
            } else {
                    //do something

Correct use of transactions in SQL Server

Add a try/catch block, if the transaction succeeds it will commit the changes, if the transaction fails the transaction is rolled back:



      INSERT INTO [Test].[dbo].[T1] ([Title], [AVG])
      VALUES ('Tidd130', 130), ('Tidd230', 230)

      UPDATE [Test].[dbo].[T1]
      SET [Title] = N'az2' ,[AVG] = 1
      WHERE [dbo].[T1].[Title] = N'az'






Displaying the Error Messages in Laravel after being Redirected from controller

Laravel 4

When the validation fails return back with the validation errors.

if($validator->fails()) {
    return Redirect::back()->withErrors($validator);

You can catch the error on your view using

    {{ implode('', $errors->all('<div>:message</div>')) }}


To display error under each field you can do like this.

<input type="text" name="firstname">
    <div class="error">{{ $errors->first('firstname') }}</div>

For better display style with css.

You can refer to the docs here.


To display all errors at once

    {!! implode('', $errors->all('<div>:message</div>')) !!}

To display error under each field.

    <div class="error">{{ $message }}</div>

How to insert data into elasticsearch

I started off using curl, but since have migrated to use kibana. Here is some more information on the ELK stack from (E elastic search, K kibana):

With kibana your POST requests are a bit more simple:

    "field": "value",
    "id": 1,
    "account_id": 213,
    "name": "kimchy"

changing textbox border colour using javascript

I'm agree with Vicente Plata you should try using jQuery IMHO is the best javascript library. You can create a class in your CSS file and just do the following with jquery:


and that's all, and of course you won't be worried about incompatibility of the browsers, that's jquery's team problem :D LOL

Where and why do I have to put the "template" and "typename" keywords?

This answer is meant to be a rather short and sweet one to answer (part of) the titled question. If you want an answer with more detail that explains why you have to put them there, please go here.

The general rule for putting the typename keyword is mostly when you're using a template parameter and you want to access a nested typedef or using-alias, for example:

template<typename T>
struct test {
    using type = T; // no typename required
    using underlying_type = typename T::type // typename required

Note that this also applies for meta functions or things that take generic template parameters too. However, if the template parameter provided is an explicit type then you don't have to specify typename, for example:

template<typename T>
struct test {
    // typename required
    using type = typename std::conditional<true, const T&, T&&>::type;
    // no typename required
    using integer = std::conditional<true, int, float>::type;

The general rules for adding the template qualifier are mostly similar except they typically involve templated member functions (static or otherwise) of a struct/class that is itself templated, for example:

Given this struct and function:

template<typename T>
struct test {
    template<typename U>
    void get() const {
        std::cout << "get\n";

template<typename T>
void func(const test<T>& t) {
    t.get<int>(); // error

Attempting to access t.get<int>() from inside the function will result in an error:

main.cpp:13:11: error: expected primary-expression before 'int'
main.cpp:13:11: error: expected ';' before 'int'

Thus in this context you would need the template keyword beforehand and call it like so:

t.template get<int>()

That way the compiler will parse this properly rather than t.get < int.

Best Practice: Software Versioning

We use a.b.c.d where

  • a - major (incremented on delivery to client)
  • b - minor (incremented on delivery to client)
  • c - revision (incremented on internal releases)
  • d - build (incremented by cruise control)

Best practice when adding whitespace in JSX

I have been trying to think of a good convention to use when placing text next to components on different lines, and found a couple good options:

    Hello {


    Hello {}
    {} again!

Each of these produces clean html without additional &nbsp; or other extraneous markup. It creates fewer text nodes than using {' '}, and allows using of html entities where {' hello &amp; goodbye '} does not.

What is the meaning of prepended double colon "::"?

:: is the scope resolution operator. It's used to specify the scope of something.

For example, :: alone is the global scope, outside all other namespaces.

some::thing can be interpreted in any of the following ways:

  • some is a namespace (in the global scope, or an outer scope than the current one) and thing is a type, a function, an object or a nested namespace;
  • some is a class available in the current scope and thing is a member object, function or type of the some class;
  • in a class member function, some can be a base type of the current type (or the current type itself) and thing is then one member of this class, a type, function or object.

You can also have nested scope, as in some::thing::bad. Here each name could be a type, an object or a namespace. In addition, the last one, bad, could also be a function. The others could not, since functions can't expose anything within their internal scope.

So, back to your example, ::thing can be only something in the global scope: a type, a function, an object or a namespace.

The way you use it suggests (used in a pointer declaration) that it's a type in the global scope.

I hope this answer is complete and correct enough to help you understand scope resolution.

How do I check for vowels in JavaScript?

I kind of like this method which I think covers all the bases:

const matches = str.match(/aeiou/gi];
return matches ? matches.length : 0;

Find unused code

The truth is that the tool can never give you a 100% certain answer, but coverage tool can give you a pretty good run for the money.

If you count with comprehensive unit test suite, than you can use test coverage tool to see exactly what lines of code were not executed during the test run. You will still need to analyze the code manually: either eliminate what you consider dead code or write test to improve test coverage.

One such tool is NCover, with open source precursor on Sourceforge. Another alternative is PartCover.

Check out this answer on stackoverflow.

Directory-tree listing in Python

You can use


For reference and more os functions look here:

Google Maps API v3 adding an InfoWindow to each marker

I had a similar problem. If all you want is for some info to be displayed when you hover over a marker, instead of clicking it, then I found that a good alternative to using an info Window was to set a title on the marker. That way whenever you hover the mouse over the marker the title displays like an ALT tag. 'marker.setTitle('Marker '+id);' It removes the need to create a listener for the marker too

Could not load the Tomcat server configuration

I've just solved this exact problem on my Ubuntu 14.04 with Eclipse Mars 2.

This could happen when Eclipse is not finding Tomcat's configuration files where they are expected to be. This place is in


(by default if you didn't changed server's name). So you have to copy all the files under your $tomcat_installation_folder/conf/* to the workspace server's folder.

But it was easier to just remove the server from your server list and add it again. Eclipse will automatically recreate all these files again into the proper folders. Like in the picture below:

enter image description here

In my case I've downloaded tomcat-8.0.35 from the website, so the configuration files needed are in /opt/apache-tomcat-8.0.35/conf/ filesystem.

Just delete the desired server from the Servers view (Window -> Show View -> Servers) and then go to Window -> Preferences -> Server -> Runtime Environment -> Add and add the server again.

bootstrap button shows blue outline when clicked

Try the below

.bootstrap-select .dropdown-toggle:focus 
          outline: 0 !important;

Formatting a number with exactly two decimals in JavaScript

You could also use the .toPrecision() method and some custom code, and always round up to the nth decimal digit regardless the length of int part.

function glbfrmt (number, decimals, seperator) {
    return typeof number !== 'number' ? number : number.toPrecision( number.toString().split(seperator)[0].length + decimals);

You could also make it a plugin for a better use.

Securing a password in a properties file

The poor mans compromise solution is to use a simplistic multi signature approach.

For Example the DBA sets the applications database password to a 50 character random string. TAKqWskc4ncvKaJTyDcgAHq82X7tX6GfK2fc386bmNw3muknjU

He or she give half the password to the application developer who then hard codes it into the java binary.

private String pass1 = "TAKqWskc4ncvKaJTyDcgAHq82"

The other half of the password is passed as a command line argument. the DBA gives pass2 to the system support or admin person who either enters it a application start time or puts it into the automated application start up script.

java -jar /myapplication.jar -pass2 X7tX6GfK2fc386bmNw3muknjU

When the application starts it uses pass1 + pass2 and connects to the database.

This solution has many advantages with out the downfalls mentioned.

You can safely put half the password in a command line arguments as reading it wont help you much unless you are the developer who has the other half of the password.

The DBA can also still change the second half of the password and the developer need not have to re-deploy the application.

The source code can also be semi public as reading it and the password will not give you application access.

You can further improve the situation by adding restrictions on the IP address ranges the database will accept connections from.

Docker how to change repository name or rename image?


how to use substr() function in jquery?

If you want to extract from a tag then


With the mouseover event,

$(this).text($(this).text().substr(0, 25));

The above will extract the text of a tag, then extract again assign it back.

How do you get the current time of day?




How to create an integer array in Python?

a = 10 * [0]

gives you an array of length 10, filled with zeroes.

Fetch first element which matches criteria

When you write a lambda expression, the argument list to the left of -> can be either a parenthesized argument list (possibly empty), or a single identifier without any parentheses. But in the second form, the identifier cannot be declared with a type name. Thus: s-> s.getStation().getName().equals(name));

is incorrect syntax; but s)-> s.getStation().getName().equals(name));

is correct. Or: -> s.getStation().getName().equals(name));

is also correct if the compiler has enough information to figure out the types.

CodeIgniter 404 Page Not Found, but why?

If you installed new Codeigniter, please check if you added .htaccess file on root directory. If you didn't add it yet, please add it. You can put default content it the .htaccess file like below.

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /

#Removes access to the system folder by users.
#Additionally this will allow you to create a System.php controller,
#previously this would not have been possible.
#'system' can be replaced if you have renamed your system folder.
RewriteCond %{REQUEST_URI} ^system.*
RewriteRule ^(.*)$ /index.php?/$1 [L]

#When your application folder isn't in the system folder
#This snippet prevents user access to the application folder
#Submitted by: Fabdrol
#Rename 'application' to your applications folder name.
RewriteCond %{REQUEST_URI} ^application.*
RewriteRule ^(.*)$ /index.php?/$1 [L]

#Checks to see if the user is attempting to access a valid file,
#such as an image or css document, if this isn't true it sends the
#request to index.php
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L]

<IfModule !mod_rewrite.c>
# If we don't have mod_rewrite installed, all 404's
# can be sent to index.php, and everything works as normal.
# Submitted by: ElliotHaughin

ErrorDocument 404 /index.php

What possibilities can cause "Service Unavailable 503" error?

Your web pages are served by an application pool. If you disable/stop the application pool, and anyone tries to browse the application, you will get a Service Unavailable. It can happen due to multiple reasons...

  1. Your application may have crashed [check the event viewer and see if you can find event logs in your Application/System log]

  2. Your application may be crashing very frequently. If an app pool crashes for 5 times in 5 minutes [check your application pool settings for rapid fail], your application pool is disabled by IIS and you will end up getting this message.

In either case, the issue is that your worker process is failing and you should troubleshoot it from crash perspective.

What is a Crash (technically)... in ASP.NET and what to do if it happens?

Removing the textarea border in HTML

This one is great:

<style type="text/css">
width: 100%;
height: 100%;
border-color: Transparent;     
<textarea class="test"></textarea>

Use nginx to serve static files from subdirectories of a given directory

It should work, however says:

When location matches the last part of the directive’s value: it is better to use the root directive instead:

which would yield:

server {
  listen        8080;
  error_log     /home/www-data/logs/nginx_www.error.log;
  error_page    404    /404.html;

  location /public/doc/ {
    autoindex on;
    root  /home/www-data/mysite;

  location = /404.html {
    root /home/www-data/mysite/static/html;

Convert String to Double - VB

Dim text As String = "123.45"
Dim value As Double
If Double.TryParse(text, value) Then
    ' text is convertible to Double, and value contains the Double value now
    ' Cannot convert text to Double
End If

How does an SSL certificate chain bundle work?

The original order is in fact backwards. Certs should be followed by the issuing cert until the last cert is issued by a known root per IETF's RFC 5246 Section 7.4.2

This is a sequence (chain) of certificates. The sender's certificate MUST come first in the list. Each following certificate MUST directly certify the one preceding it.

See also SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch for troubleshooting techniques.

But I still don't know why they wrote the spec so that the order matters.

Math.random() versus Random.nextInt(int)

According to this example Random.nextInt(n) has less predictable output then Math.random() * n. According to [sorted array faster than an unsorted array][1] I think we can say Random.nextInt(n) is hard to predict.

usingRandomClass : time:328 milesecond.

usingMathsRandom : time:187 milesecond.

package javaFuction;
import java.util.Random;
public class RandomFuction 
    static int array[] = new int[9999];
    static long sum = 0;
    public static void usingMathsRandom() {
        for (int i = 0; i < 9999; i++) {
         array[i] = (int) (Math.random() * 256);

        for (int i = 0; i < 9999; i++) {
            for (int j = 0; j < 9999; j++) {
                if (array[j] >= 128) {
                    sum += array[j];

    public static void usingRandomClass() {
        Random random = new Random();
        for (int i = 0; i < 9999; i++) {
            array[i] = random.nextInt(256);

        for (int i = 0; i < 9999; i++) {
            for (int j = 0; j < 9999; j++) {
                if (array[j] >= 128) {
                    sum += array[j];



    public static void main(String[] args) {
        long start = System.currentTimeMillis();
        long end = System.currentTimeMillis();
        System.out.println("usingRandomClass " + (end - start));
        start = System.currentTimeMillis();
        end = System.currentTimeMillis();
        System.out.println("usingMathsRandom " + (end - start));



Select multiple columns by labels in pandas

How do I select multiple columns by labels in pandas?

Multiple label-based range slicing is not easily supported with pandas, but position-based slicing is, so let's try that instead:

loc = df.columns.get_loc
df.iloc[:, np.r_[loc('A'):loc('C')+1, loc('E'), loc('G'):loc('I')+1]]

          A         B         C         E         G         H         I
0 -1.666330  0.321260 -1.768185 -0.034774  0.023294  0.533451 -0.241990
1  0.911498  3.408758  0.419618 -0.462590  0.739092  1.103940  0.116119
2  1.243001 -0.867370  1.058194  0.314196  0.887469  0.471137 -1.361059
3 -0.525165  0.676371  0.325831 -1.152202  0.606079  1.002880  2.032663
4  0.706609 -0.424726  0.308808  1.994626  0.626522 -0.033057  1.725315
5  0.879802 -1.961398  0.131694 -0.931951 -0.242822 -1.056038  0.550346
6  0.199072  0.969283  0.347008 -2.611489  0.282920 -0.334618  0.243583
7  1.234059  1.000687  0.863572  0.412544  0.569687 -0.684413 -0.357968
8 -0.299185  0.566009 -0.859453 -0.564557 -0.562524  0.233489 -0.039145
9  0.937637 -2.171174 -1.940916 -1.553634  0.619965 -0.664284 -0.151388

Note that the +1 is added because when using iloc the rightmost index is exclusive.

Comments on Other Solutions

  • filter is a nice and simple method for OP's headers, but this might not generalise well to arbitrary column names.

  • The "location-based" solution with loc is a little closer to the ideal, but you cannot avoid creating intermediate DataFrames (that are eventually thrown out and garbage collected) to compute the final result range -- something that we would ideally like to avoid.

  • Lastly, "pick your columns directly" is good advice as long as you have a manageably small number of columns to pick. It will, however not be applicable in some cases where ranges span dozens (or possibly hundreds) of columns.

E: Unable to locate package npm

I ran into the same issue on Debian 9.2, this is what I did to overcome it.


sudo apt install curl
curl -sL | sudo bash -
sudo apt-get install -y nodejs
sudo apt-get install -y npm

Check installed versions

node --version
npm --version

Originally sourced from "How to install Node.js LTS on Debian 9 stretch"

ORDER BY date and time BEFORE GROUP BY name in mysql

I think this is what you are seeking :

SELECT name, min(date)
FROM myTable
ORDER BY min(date)

For the time, you have to make a mysql date via STR_TO_DATE :

STR_TO_DATE(date + ' ' + time, '%Y-%m-%d %h:%i:%s')

So :

SELECT name, min(STR_TO_DATE(date + ' ' + time, '%Y-%m-%d %h:%i:%s'))
FROM myTable
ORDER BY min(STR_TO_DATE(date + ' ' + time, '%Y-%m-%d %h:%i:%s'))

Android: How to turn screen on and off programmatically?

I am going to assume you only want this to be in effect while your application is in the foreground.

This code:

params.flags |= LayoutParams.FLAG_KEEP_SCREEN_ON;
params.screenBrightness = 0;

Does not turn the screen off in the traditional sense. It makes the screen as dim as possible. In the standard platform there is a limit to how dim it can be; if your device is actually allowing the screen to turn completely off, then it is some peculiarity of the implementation of that device and not a behavior you can count on across devices.

In fact using this in conjunction with FLAG_KEEP_SCREEN_ON means that you will never allow the screen to go off (and thus the device to go into low-power mode) even if the particular device is allowing you to set the screen brightness to full-off. Keep this very strongly in mind. You will be using much more power than you would if the screen was really off.

Now for turning the screen back to regular brightness, just setting the brightness value should do it:

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = -1;

I can't explain why this wouldn't replace the 0 value you had previously set. As a test, you could try putting a forced full brightness in there to force to that specific brightness:

WindowManager.LayoutParams params = getWindow().getAttributes();
params.screenBrightness = 1;

This definitely works. For example, Google's Books apps uses this to allow you to set the screen brightness to dim while using a book and then return to regular brightness when turning that off.

To help debug, you can use "adb shell dumpsys window" to see the current state of your window. In the data for your window, it will tell you the current LayoutParams that have been set for it. Ensure the value you think is actually there.

And again, FLAG_KEEP_SCREEN_ON is a separate concept; it and the brightness have no direct impact on each other. (And there would be no reason to set the flag again when undoing the brightness, if you had already set it when putting the brightness to 0. The flag will stay set until you change it.)

Mailto: Body formatting

Forget it; this might work with Outlook or maybe even GMail but you won't be able to get this working properly supporting most other E-mail clients out there (and there's a shitton of 'em).

You're better of using a simple PHP script (check out PHPMailer) or use a hosted solution (Google "email form hosted", "free email form hosting" or something similar)

By the way, you are looking for the term "Percent-encoding" (also called url-encoding and Javascript uses encodeUri/encodeUriComponent (make sure you understand the differences!)). You will need to encode a whole lot more than just newlines.