Programs & Examples On #Touchesbegan

Swift addsubview and remove it

You have to use the viewWithTag function to find the view with the given tag.

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    let touch = touches.anyObject() as UITouch
    let point = touch.locationInView(self.view)

    if let viewWithTag = self.view.viewWithTag(100) {
        print("Tag 100")
    } else {
        print("tag not found")

Using isKindOfClass with Swift

I would use:

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {

    super.touchesBegan(touches, withEvent: event)
    let touch : UITouch = touches.anyObject() as UITouch

    if let touchView = touch.view as? UIPickerView


How to dismiss keyboard iOS programmatically when pressing return

for swift 3-4 i fixed like

func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
    return false

just copy paste anywhere on the class. This solution just work if you want all UItextfield work as same, or if you have just one!

UITapGestureRecognizer - single tap and double tap

Some view have there own double tap recognizers built in (MKMapView being an example). To get around this you will need to implement UIGestureRecognizerDelegate method shouldRecognizeSimultaneouslyWithGestureRecognizer and return YES:

First implement your double and single recognizers:

// setup gesture recognizers
UITapGestureRecognizer* singleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self
singleTapRecognizer.delegate = self;
singleTapRecognizer.numberOfTapsRequired = 1;

UITapGestureRecognizer* doubleTapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self
doubleTapRecognizer.delegate = self;    // this allows
doubleTapRecognizer.numberOfTapsRequired = 2;
[singleTapRecognizer requireGestureRecognizerToFail:doubleTapRecognizer];

And then implement:

#pragma mark UIGestureRecognizerDelegate
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer
*)otherGestureRecognizer {  return YES; }

How to add a touch event to a UIView?

In iOS 3.2 and higher, you can use gesture recognizers. For example, this is how you would handle a tap event:

//The setup code (in viewDidLoad in your view controller)
UITapGestureRecognizer *singleFingerTap = 
  [[UITapGestureRecognizer alloc] initWithTarget:self 
[self.view addGestureRecognizer:singleFingerTap];

//The event handling method
- (void)handleSingleTap:(UITapGestureRecognizer *)recognizer
  CGPoint location = [recognizer locationInView:[recognizer.view superview]];

  //Do stuff here...

There are a bunch of built in gestures as well. Check out the docs for iOS event handling and UIGestureRecognizer. I also have a bunch of sample code up on github that might help.

Run jQuery function onclick

Why do you need to attach it to the HTML? Just bind the function with hover

$("div.system_box").hover(function(){ mousin }, 
                          function() { mouseout });

If you do insist to have JS references inside the html, which is usualy a bad idea you can use:


after topic edit:

<div class="system_box" data-target="sms_box">


$("div.system_box").click(function(){ slideonlyone($(this).attr("data-target")); });

Datetime in where clause

Assuming we're talking SQL Server DateTime

Note: BETWEEN includes both ends of the range, so technically this pattern will be wrong:

errorDate BETWEEN '12/20/2008' AND '12/21/2008'

My preferred method for a time range like that is:

'20081220' <= errorDate AND errordate < '20081221'

Works with common indexes (range scan, SARGable, functionless) and correctly clips off midnight of the next day, without relying on SQL Server's time granularity (e.g. 23:59:59.997)

How do I resize an image using PIL and maintain its aspect ratio?

Open your image file

from PIL import Image
im ="image.png")

Use PIL Image.resize(size, resample=0) method, where you substitute (width, height) of your image for the size 2-tuple.

This will display your image at original size:

display(im.resize((int(im.size[0]),int(im.size[1])), 0) )

This will display your image at 1/2 the size:

display(im.resize((int(im.size[0]/2),int(im.size[1]/2)), 0) )

This will display your image at 1/3 the size:

display(im.resize((int(im.size[0]/3),int(im.size[1]/3)), 0) )

This will display your image at 1/4 the size:

display(im.resize((int(im.size[0]/4),int(im.size[1]/4)), 0) )

etc etc

"multiple target patterns" Makefile error

Besides having to escape colons as in the original answer, I have found if the indentation is off you could potentially get the same problem. In one makefile, I had to replace spaces with a tab and that allowed me to get past the error.

How to delete selected text in the vi editor

When using a terminal like PuTTY, usually mouse clicks and selections are not transmitted to the remote system. So, vi has no idea that you just selected some text. (There are exceptions to this, but in general mouse actions aren't transmitted.)

To delete multiple lines in vi, use something like 5dd to delete 5 lines.

If you're not using Vim, I would strongly recommend doing so. You can use visual selection, where you press V to start a visual block, move the cursor to the other end, and press d to delete (or any other editing command, such as y to copy).

linq query to return distinct field values from a list of objects

I think this is what your looking for:

    var objs= (from c in List_Objects 
orderby c.TypeID  select c).GroupBy(g=>g.TypeID).Select(x=>x.FirstOrDefault());      

Similar to this Returning a Distinct IQueryable with LINQ?

Apache Spark: The number of cores vs. the number of executors

From the excellent resources available at RStudio's Sparklyr package page:


It may be useful to provide some simple definitions for the Spark nomenclature:

Node: A server

Worker Node: A server that is part of the cluster and are available to run Spark jobs

Master Node: The server that coordinates the Worker nodes.

Executor: A sort of virtual machine inside a node. One Node can have multiple Executors.

Driver Node: The Node that initiates the Spark session. Typically, this will be the server where sparklyr is located.

Driver (Executor): The Driver Node will also show up in the Executor list.

ComboBox- SelectionChanged event has old value, not new value

The second option didn't work for me because the .Text element was out of scope (C# 4.0 VS2008). This was my solution...

string test = null;
foreach (ComboBoxItem item in e.AddedItems)
   test = item.Content.ToString();

Trim leading and trailing spaces from a string in awk

remove leading and trailing white space in 2nd column

awk 'BEGIN{FS=OFS=","}{gsub(/^[ \t]+/,"",$2);gsub(/[ \t]+$/,"",$2)}1' input.txt

another way by one gsub:

awk 'BEGIN{FS=OFS=","} {gsub(/^[ \t]+|[ \t]+$/, "", $2)}1' infile

Why doesn't the height of a container element increase if it contains floated elements?

You are encountering the float bug (though I'm not sure if it's technically a bug due to how many browsers exhibit this behaviour). Here is what is happening:

Under normal circumstances, assuming that no explicit height has been set, a block level element such as a div will set its height based on its content. The bottom of the parent div will extend beyond the last element. Unfortunately, floating an element stops the parent from taking the floated element into account when determining its height. This means that if your last element is floated, it will not "stretch" the parent in the same way a normal element would.


There are two common ways to fix this. The first is to add a "clearing" element; that is, another element below the floated one that will force the parent to stretch. So add the following html as the last child:

<div style="clear:both"></div>

It shouldn't be visible, and by using clear:both, you make sure that it won't sit next to the floated element, but after it.


The second method, which is preferred by most people (I think) is to change the CSS of the parent element so that the overflow is anything but "visible". So setting the overflow to "hidden" will force the parent to stretch beyond the bottom of the floated child. This is only true if you haven't set a height on the parent, of course.

Like I said, the second method is preferred as it doesn't require you to go and add semantically meaningless elements to your markup, but there are times when you need the overflow to be visible, in which case adding a clearing element is more than acceptable.

function declaration isn't a prototype

In C int foo() and int foo(void) are different functions. int foo() accepts an arbitrary number of arguments, while int foo(void) accepts 0 arguments. In C++ they mean the same thing. I suggest that you use void consistently when you mean no arguments.

If you have a variable a, extern int a; is a way to tell the compiler that a is a symbol that might be present in a different translation unit (C compiler speak for source file), don't resolve it until link time. On the other hand, symbols which are function names are anyway resolved at link time. The meaning of a storage class specifier on a function (extern, static) only affects its visibility and extern is the default, so extern is actually unnecessary.

I suggest removing the extern, it is extraneous and is usually omitted.

how to save canvas as png image?

I had this problem and this is the best solution without any external or additional script libraries: In Javascript tags or file create this function: We assume here that canvas is your canvas:

function download(){
        var download = document.getElementById("download");
        var image = document.getElementById("canvas").toDataURL("image/png")
                    .replace("image/png", "image/octet-stream");
        download.setAttribute("href", image);


In the body part of your HTML specify the button:

<a id="download" download="image.png"><button type="button" onClick="download()">Download</button></a>

This is working and download link looks like a button. Tested in Firefox and Chrome.

Turning a Comma Separated string into individual rows

You can use the following function to extract data

CREATE FUNCTION [dbo].[SplitString]
    @RowData NVARCHAR(MAX),
    @Delimeter NVARCHAR(MAX)
    DECLARE @Iterator INT
    SET @Iterator = 1

    DECLARE @FoundIndex INT
    SET @FoundIndex = CHARINDEX(@Delimeter,@RowData)

    WHILE (@FoundIndex>0)
        INSERT INTO @RtnValue (data)
            Data = LTRIM(RTRIM(SUBSTRING(@RowData, 1, @FoundIndex - 1)))

        SET @RowData = SUBSTRING(@RowData,
                @FoundIndex + DATALENGTH(@Delimeter) / 2,

        SET @Iterator = @Iterator + 1
        SET @FoundIndex = CHARINDEX(@Delimeter, @RowData)

    INSERT INTO @RtnValue (Data)
    SELECT Data = LTRIM(RTRIM(@RowData))


How to pass arguments to a Dockerfile?

You are looking for --build-arg and the ARG instruction. These are new as of Docker 1.9. Check out This will allow you to add ARG arg to the Dockerfile and then build with docker build --build-arg arg=2.3 ..

In c# what does 'where T : class' mean?

Simply put this is constraining the generic parameter to a class (or more specifically a reference type which could be a class, interface, delegate, or array type).

See this MSDN article for further details.

Call a function after previous function is complete

This answer uses promises, a JavaScript feature of the ECMAScript 6 standard. If your target platform does not support promises, polyfill it with PromiseJs.

Promises are a new (and a lot better) way to handle asynchronous operations in JavaScript:

    if (condition == 'true'){
        function1(someVariable).then(function() {
            //this function is executed after function1
    else {

function function1(param, callback) {
    return new Promise(function (fulfill, reject){
        //do stuff
        fulfill(result); //if the action succeeded
        reject(error); //if the action did not succeed

This may seem like a significant overhead for this simple example, but for more complex code it is far better than using callbacks. You can easily chain multiple asynchronous calls using multiple then statements:

function1(someVariable).then(function() {
}).then(function() {

You can also wrap jQuery deferrds easily (which are returned from $.ajax calls):

Promise.resolve($.ajax(...params...)).then(function(result) {
    //whatever you want to do after the request

As @charlietfl noted, the jqXHR object returned by $.ajax() implements the Promise interface. So it is not actually necessary to wrap it in a Promise, it can be used directly:

$.ajax(...params...).then(function(result) {
    //whatever you want to do after the request

How to sort in mongoose?


Post.find().sort({'updatedAt': -1}).all((posts) => {
  // do something with the array of posts


Post.find().sort([['updatedAt', 'descending']]).all((posts) => {
  // do something with the array of posts

How does Java resolve a relative path in new File()?

There is a concept of a working directory.
This directory is represented by a . (dot).
In relative paths, everything else is relative to it.

Simply put the . (the working directory) is where you run your program.
In some cases the working directory can be changed but in general this is
what the dot represents. I think this is C:\JavaForTesters\ in your case.

So test\..\test.txt means: the sub-directory test
in my working directory, then one level up, then the
file test.txt. This is basically the same as just test.txt.

For more details check here.

Hibernate Group by Criteria Object

Please refer to this for the example .The main point is to use the groupProperty() , and the related aggregate functions provided by the Projections class.

For example :

SELECT column_name, max(column_name) , min (column_name) , count(column_name)
FROM table_name
WHERE column_name > xxxxx
GROUP BY column_name

Its equivalent criteria object is :

List result = session.createCriteria(SomeTable.class)       
                    .add("someColumn", xxxxx))      

Git: How to find a deleted file in the project commit history?

Suppose you want to recover a file called MyFile, but are uncertain of its path (or its extension, for that matter):

Preliminary: Avoid confusion by stepping to the git root

A nontrivial project may have multiple directories with similar or identical filenames.

> cd <project-root>
  1. Find the full path

    git log --diff-filter=D --summary | grep delete | grep MyFile

    delete mode 100644 full/path/to/MyFile.js

full/path/to/MyFile.js is the path & file you're seeking.

  1. Determine all the commits that affected that file

    git log --oneline --follow -- full/path/to/MyFile.js

    bd8374c Some helpful commit message

    ba8d20e Another prior commit message affecting that file

    cfea812 The first message for a commit in which that file appeared.

  2. Checkout the file

If you choose the first-listed commit (the last chronologically, here bd8374c), the file will not be found, since it was deleted in that commit.

> git checkout bd8374c -- full/path/to/MyFile.js

`error: pathspec 'full/path/to/MyFile.js' did not match any file(s) known to git.`

Just select the preceding (append a caret) commit:

> git checkout bd8374c^ -- full/path/to/MyFile.js

How to add custom Http Header for C# Web Service Client consuming Axis 1.4 Web service

Are we talking WCF here? I had issues where the service calls were not adding the http authorization headers, wrapping any calls into this statement fixed my issue.

  using (OperationContextScope scope = new OperationContextScope(RefundClient.InnerChannel))
            var httpRequestProperty = new HttpRequestMessageProperty();
            httpRequestProperty.Headers[System.Net.HttpRequestHeader.Authorization] = "Basic " +
            Convert.ToBase64String(Encoding.ASCII.GetBytes(RefundClient.ClientCredentials.UserName.UserName + ":" +
            OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = httpRequestProperty;

            PaymentResponse = RefundClient.Payment(PaymentRequest);

This was running SOAP calls to IBM ESB via .NET with basic auth over http or https.

I hope this helps someone out because I had massive issues finding a solution online.

How can I open a .db file generated by eclipse(android) form DDMS-->File explorer-->data--->data-->packagename-->database?

One of the way to browse your database is to use questoid sqlite manager.

# 1. Download questoid manager from this link .

# 2. Drop this file into your eclipse --> dropins.

# 3. Restart your eclipse.

# 4. Now go to your file explorer and click your database. you can find a blue database icon enabled in the top right corner.

# 5. Double click the icon and you can see ur inserted fields/tables/ in the database

How do you change the value inside of a textfield flutter?

step 1) Declare TextEditingController.

step 2) supply controller to the TextField.

step 3) user controller's text property to change the value of the textField.

follow this official solution to the problem

Remove a HTML tag but keep the innerHtml

Behold, for the simplest answer is mind blowing:

outerHTML is supported down to Internet Explorer 4 !

Here is to do it with javascript even without jQuery

element.outerHTML = element.innerHTML

with jQuery element = $('b')[0]; or without jQuery element = document.querySelector('b');

If you want it as a function:

function unwrap(selector) {
    var nodelist = document.querySelectorAll(selector);, function(item,i){
        item.outerHTML = item.innerHTML; // or item.innerText if you want to remove all inner html tags 


This should work in all major browser including old IE. in recent browser, we can even call forEach right on the nodelist.

function unwrap(selector) {
    document.querySelectorAll('b').forEach( (item,i) => {
        item.outerHTML = item.innerText;
    } )

jQuery check if an input is type checkbox?

>>> a=$("#communitymode")[0]
<input id="communitymode" type="checkbox" name="communitymode">
>>> a.type

Or, more of the style of jQuery:

$("#myinput").attr('type') == 'checkbox'

How to send a simple string between two programs using pipes?

A regular pipe can only connect two related processes. It is created by a process and will vanish when the last process closes it.

A named pipe, also called a FIFO for its behavior, can be used to connect two unrelated processes and exists independently of the processes; meaning it can exist even if no one is using it. A FIFO is created using the mkfifo() library function.



#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

int main()
    int fd;
    char * myfifo = "/tmp/myfifo";

    /* create the FIFO (named pipe) */
    mkfifo(myfifo, 0666);

    /* write "Hi" to the FIFO */
    fd = open(myfifo, O_WRONLY);
    write(fd, "Hi", sizeof("Hi"));

    /* remove the FIFO */

    return 0;


#include <fcntl.h>
#include <stdio.h>
#include <sys/stat.h>
#include <unistd.h>

#define MAX_BUF 1024

int main()
    int fd;
    char * myfifo = "/tmp/myfifo";
    char buf[MAX_BUF];

    /* open, read, and display the message from the FIFO */
    fd = open(myfifo, O_RDONLY);
    read(fd, buf, MAX_BUF);
    printf("Received: %s\n", buf);

    return 0;

Note: Error checking was omitted from the above code for simplicity.

How to get the hours difference between two date objects?

Use the timestamp you get by calling valueOf on the date object:

var diff = date2.valueOf() - date1.valueOf();
var diffInHours = diff/1000/60/60; // Convert milliseconds to hours

VBA (Excel) Initialize Entire Array without Looping

Fancy way to put @rdhs answer in a function:

Function arrayZero(size As Integer)
  arrayZero = Evaluate("=IF(ISERROR(Transpose(A1:A" & size & ")), 0, 0)")
End Function

And use like this:

myArray = arrayZero(15)

How to get base URL in Web API controller?

  1. Add a reference to System.Web using System.Web;

  2. Get the host or any other component of the url you want string host = HttpContext.Current.Request.Url.Host;

WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for 'jquery'. Please add a ScriptResourceMapping named jquery(case-sensitive)

There are at least three ways to disable the use of unobtrusive JavaScript for client-side validation:

  1. Add the following to the web.config file:
        <add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />
  2. Set the value of the System.Web.UI.ValidationSettings.UnobtrusiveValidationMode static property to System.Web.UI.UnobtrusiveValidationMode.None
  3. Set the value of the System.Web.UI.Page.UnobtrusiveValidationMode instance property to System.Web.UI.UnobtrusiveValidationMode.None

To disable the functionality on a per page basis, I prefer to set the Page.UnobtrusiveValidationMode property using the page directive:

<%@ Page Language="C#" UnobtrusiveValidationMode="None" %>

text box input height

You can define a class or id for input fields.


input {
    line-height: 20px;

Hope this helps you.

Failed to resolve:

  1. Add this in build.gradle(Project:projectname)

    allprojects {
      repositories {
        maven { url "" }
  2. Add this in build.gradle(Module:app)

    dependencies {
      compile ''

Should I use scipy.pi, numpy.pi, or math.pi?

>>> import math
>>> import numpy as np
>>> import scipy
>>> math.pi == np.pi == scipy.pi

So it doesn't matter, they are all the same value.

The only reason all three modules provide a pi value is so if you are using just one of the three modules, you can conveniently have access to pi without having to import another module. They're not providing different values for pi.

ReferenceError: event is not defined error in Firefox

You're declaring (some of) your event handlers incorrectly:

$('.menuOption').click(function( event ){ // <---- "event" parameter here

    var categories = $(this).attr('rel');


You need "event" to be a parameter to the handlers. WebKit follows IE's old behavior of using a global symbol for "event", but Firefox doesn't. When you're using jQuery, that library normalizes the behavior and ensures that your event handlers are passed the event parameter.

edit — to clarify: you have to provide some parameter name; using event makes it clear what you intend, but you can call it e or cupcake or anything else.

Note also that the reason you probably should use the parameter passed in from jQuery instead of the "native" one (in Chrome and IE and Safari) is that that one (the parameter) is a jQuery wrapper around the native event object. The wrapper is what normalizes the event behavior across browsers. If you use the global version, you don't get that.

Why are iframes considered dangerous and a security risk?

"Dangerous" and "Security risk" are not the first things that spring to mind when people mention iframes … but they can be used in clickjacking attacks.

CSS root directory

I use a relative path solution,


every ../ will take you one folder up towards the root. Hope this helps..

How to embed fonts in CSS?

One of the best source of information on this topic is Paul Irish's Bulletproof @font-face syntax article.

Read it and you will end with something like:

/* definition */
@font-face {
  font-family: EntezareZohoor2;
  src: url('fonts/EntezareZohoor2.eot');
  src: url('fonts/EntezareZohoor2.eot?') format('?'),
       url('fonts/EntezareZohoor2.woff') format('woff'),
       url('fonts/EntezareZohoor2.ttf') format('truetype');
  font-weight: normal;
  font-style: normal;

/* use */
body {
    font-family: EntezareZohoor2, Tahoma, serif;

Animation fade in and out

According to the documentation AnimationSet

Represents a group of Animations that should be played together. The transformation of each individual animation are composed together into a single transform. If AnimationSet sets any properties that its children also set (for example, duration or fillBefore), the values of AnimationSet override the child values

AnimationSet mAnimationSet = new AnimationSet(false); //false means don't share interpolators

Pass true if all of the animations in this set should use the interpolator associated with this AnimationSet. Pass false if each animation should use its own interpolator.

ImageView imageView= (ImageView)findViewById(;
Animation fadeInAnimation = AnimationUtils.loadAnimation(this, R.anim.fade_in);
Animation fadeOutAnimation = AnimationUtils.loadAnimation(this, R.anim.fade_out);

I hope this will help you.

XAMPP - Apache could not start - Attempting to start Apache service

My scenario was different after I tested all the possible options. If you have changed the ports and still get the same problem, well here's something you can try out. This was done in Windows 7.

Step 1: Confirm the cause of the error by going to Control Panel -> System and Security -> Administrative Tools -> Event Viewer -> Windows Logs -> Application -> Error. Mine said "The Apache service named reported the following error:

httpd.exe: Syntax error on line 424 of C:/xampp/apache/conf/httpd.conf: Cannot load c:\xampp\php\php5apache.dll into server: The specified module could not be found." So I needed to change \php5apache.dll to the version of my php and apache version installed which was php7apache2_4.dll

Step 2: To get the correct name for your .dll php and apache file, got to C:\xampp\php. You will see something like php7apache2_4.dll with other files in the folder.

Step 3: Go to C:/xampp/apache/conf/httpd.conf and edit the configuration file and change "c:\xampp\php\php5apache.dll" to "c:\xampp\php\php7apache2_4.dll" in my case. Make sure you open the file as administrator save changes made.

Step 4: Run the xampp server and everything should work fine. Do not forget to shut down the xampp server before doing the changes to the apache configuration file.

Hope this helps. Cheers! :)

How can I check whether a option already exist in select by JQuery

Does not work, you have to do this:

if ( $("#your_select_id option[value='enter_value_here']").length == 0 ){
  alert("option doesn't exist!");

Pick any kind of file via an Intent in Android

Not for camera but for other files..

In my device I have ES File Explorer installed and This simply thing works in my case..

Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
startActivityForResult(intent, PICKFILE_REQUEST_CODE);

Display image at 50% of its "native" size

Maybe one of the easiest solutions would be to use the x descriptor of the srcset attribute as such:

<!-- Original image -->
<img src="" />

<!-- With a 80% size reduction (1/0.8=1.25) -->
<img srcset=" 1.25x" />

<!-- With a 50% size reduction (1/0.5=2) -->
<img srcset=" 2x" />

Currently supported by all browsers except IE. (caniuse)

MDN documentation

selectOneMenu ajax events

The PrimeFaces ajax events sometimes are very poorly documented, so in most cases you must go to the source code and check yourself.

p:selectOneMenu supports change event:

<p:selectOneMenu ..>
    <p:ajax event="change" update="msgtext"
        listener="#{post.subjectSelectionChanged}" />

which triggers listener with AjaxBehaviorEvent as argument in signature:

public void subjectSelectionChanged(final AjaxBehaviorEvent event)  {...}

Paste a multi-line Java String in Eclipse

See: Multiple-line-syntax

It also support variables in multiline string, for example:

String name="zzg";
String lines = ""/**~!{
    SELECT * 
        FROM user
        WHERE name="$name"


    FROM user
    WHERE name="zzg"

jQuery .live() vs .on() method for adding a click event after loading dynamic html

Try this:

$('#parent').on('click', '#child', function() {
    // Code

From the $.on() documentation:

Event handlers are bound only to the currently selected elements; they must exist on the page at the time your code makes the call to .on().

Your #child element doesn't exist when you call $.on() on it, so the event isn't bound (unlike $.live()). #parent, however, does exist, so binding the event to that is fine.

The second argument in my code above acts as a 'filter' to only trigger if the event bubbled up to #parent from #child.

Display Image On Text Link Hover CSS Only

From w3 schools:

/* Tooltip container */
.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted black; /* If you want dots under the hoverable text */

/* Tooltip text */
.tooltip .tooltiptext {
  visibility: hidden;
  width: 120px;
  background-color: black;
  color: #fff;
  text-align: center;
  padding: 5px 0;
  border-radius: 6px;

  /* Position the tooltip text - see examples below! */
  position: absolute;
  z-index: 1;

/* Show the tooltip text when you mouse over the tooltip container */
.tooltip:hover .tooltiptext {
  visibility: visible;

<div class="tooltip">Hover over me
  <img src="/pathtoimage" class="tooltiptext">

Sounds like about what you want

What is the meaning of Bus: error 10 in C

For one, you can't modify string literals. It's undefined behavior.

To fix that you can make str a local array:

char str[] = "First string";

Now, you will have a second problem, is that str isn't large enough to hold str2. So you will need to increase the length of it. Otherwise, you will overrun str - which is also undefined behavior.

To get around this second problem, you either need to make str at least as long as str2. Or allocate it dynamically:

char *str2 = "Second string";
char *str = malloc(strlen(str2) + 1);  //  Allocate memory
//  Maybe check for NULL.

strcpy(str, str2);

//  Always remember to free it.

There are other more elegant ways to do this involving VLAs (in C99) and stack allocation, but I won't go into those as their use is somewhat questionable.

As @SangeethSaravanaraj pointed out in the comments, everyone missed the #import. It should be #include:

#include <stdio.h>
#include <string.h>

Some projects cannot be imported because they already exist in the workspace error in Eclipse

I built the eclipse dependencies in the project terminal and then tried to import the project and it worked.

Make code in LaTeX look *nice*

The listings package is quite nice and very flexible (e.g. different sizes for comments and code).

How does Python return multiple values from a function?

Since the return statement in getName specifies multiple elements:

def getName(self):
   return self.first_name, self.last_name

Python will return a container object that basically contains them.

In this case, returning a comma separated set of elements creates a tuple. Multiple values can only be returned inside containers.

Let's use a simpler function that returns multiple values:

def foo(a, b):
    return a, b

You can look at the byte code generated by using dis.dis, a disassembler for Python bytecode. For comma separated values w/o any brackets, it looks like this:

>>> import dis
>>> def foo(a, b):
...     return a,b        
>>> dis.dis(foo)
  2           0 LOAD_FAST                0 (a)
              3 LOAD_FAST                1 (b)
              6 BUILD_TUPLE              2
              9 RETURN_VALUE

As you can see the values are first loaded on the internal stack with LOAD_FAST and then a BUILD_TUPLE (grabbing the previous 2 elements placed on the stack) is generated. Python knows to create a tuple due to the commas being present.

You could alternatively specify another return type, for example a list, by using []. For this case, a BUILD_LIST is going to be issued following the same semantics as it's tuple equivalent:

>>> def foo_list(a, b):
...     return [a, b]
>>> dis.dis(foo_list)
  2           0 LOAD_FAST                0 (a)
              3 LOAD_FAST                1 (b)
              6 BUILD_LIST               2
              9 RETURN_VALUE

The type of object returned really depends on the presence of brackets (for tuples () can be omitted if there's at least one comma). [] creates lists and {} sets. Dictionaries need key:val pairs.

To summarize, one actual object is returned. If that object is of a container type, it can contain multiple values giving the impression of multiple results returned. The usual method then is to unpack them directly:

>>> first_name, last_name = f.getName()
>>> print (first_name, last_name)

As an aside to all this, your Java ways are leaking into Python :-)

Don't use getters when writing classes in Python, use properties. Properties are the idiomatic way to manage attributes, for more on these, see a nice answer here.

socket.emit() vs. socket.send()

With socket.emit you can register custom event like that:


var io = require('').listen(80);

io.sockets.on('connection', function (socket) {
  socket.emit('news', { hello: 'world' });
  socket.on('my other event', function (data) {


var socket = io.connect('http://localhost');
socket.on('news', function (data) {
  socket.emit('my other event', { my: 'data' });

Socket.send does the same, but you don't register to 'news' but to message:


var io = require('').listen(80);

io.sockets.on('connection', function (socket) {


var socket = io.connect('http://localhost');
socket.on('message', function (message) {

Determine number of pages in a PDF file

I have good success using CeTe Dynamic PDF products. They're not free, but are well documented. They did the job for me.

Proper way to initialize C++ structs

From what you've told us it does appear to be a false positive in valgrind. The new syntax with () should value-initialize the object, assuming it is POD.

Is it possible that some subpart of your struct isn't actually POD and that's preventing the expected initialization? Are you able to simplify your code into a postable example that still flags the valgrind error?

Alternately perhaps your compiler doesn't actually value-initialize POD structures.

In any case probably the simplest solution is to write constructor(s) as needed for the struct/subparts.

How to convert an OrderedDict into a regular dict in python3

Even though this is a year old question, I would like to say that using dict will not help if you have an ordered dict within the ordered dict. The simplest way that could convert those recursive ordered dict will be

import json
from collections import OrderedDict
input_dict = OrderedDict([('method', 'constant'), ('recursive', OrderedDict([('m', 'c')]))])
output_dict = json.loads(json.dumps(input_dict))
print output_dict

mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in

That query is failing and returning false.

Put this after mysqli_query() to see what's going on.

if (!$check1_res) {
    printf("Error: %s\n", mysqli_error($con));

For more information:

Transpose list of lists

    #Import functions from library
    from numpy import size, array
    #Transpose a 2D list
    def transpose_list_2d(list_in_mat):
        list_out_mat = []
        array_in_mat = array(list_in_mat)
        array_out_mat = array_in_mat.T
        nb_lines = size(array_out_mat, 0)
        for i_line_out in range(0, nb_lines):
            array_out_line = array_out_mat[i_line_out]
            list_out_line = list(array_out_line)
        return list_out_mat

Securely storing passwords for use in python script

the secure way is encrypt your sensitive data by AES and the encryption key is derivation by password-based key derivation function (PBE), the master password used to encrypt/decrypt the encrypt key for AES.

master password -> secure key-> encrypt data by the key

You can use pbkdf2

from PBKDF2 import PBKDF2
from Crypto.Cipher import AES
import os
salt = os.urandom(8)    # 64-bit salt
key = PBKDF2("This passphrase is a secret.", salt).read(32) # 256-bit key
iv = os.urandom(16)     # 128-bit IV
cipher =, AES.MODE_CBC, iv)

make sure to store the salt/iv/passphrase , and decrypt using same salt/iv/passphase

Weblogic used similar approach to protect passwords in config files

What does %s mean in a python format string?

Here is a good example in Python3.

  >>> a = input("What is your name?")
  What is your name?Peter

  >>> b = input("Where are you from?")
  Where are you from?DE

  >>> print("So you are %s of %s" % (a, b))
  So you are Peter of DE

Formatting a Date String in React Native

Easily accomplished using a package.

Others have mentioned Moment. Moment is great but very large for a simple use like this, and unfortunately not modular so you have to import the whole package to use any of it.

I recommend using date-fns ( ( It is light-weight and modular, so you can import only the functions that you need.

In your case:

Install it: npm install date-fns --save

In your component:

import { format } from "date-fns";

var date = new Date("2016-01-04 10:34:23");

var formattedDate = format(date, "MMMM do, yyyy H:mma");


Substitute the format string above "MMMM do, yyyy H:mma" with whatever format you require.

Update: v1 vs v2 format differences

v1 used Y for year and D for day, while v2 uses y and d. Format strings above have been updated for v2; the equivalent for v1 would be "MMMM Do, YYYY H:mma" (source: Thanks @Red

How to Get the Current URL Inside @if Statement (Blade) in Laravel 4?

I'd do it this way:

@if (Request::path() == '/view')
    // code

where '/view' is view name in routes.php.

Python: Best way to add to sys.path relative to the current running script

When we try to run python file with path from terminal.

import sys
#For file name
#For first argument
dir= sys.argv[1]
print("File Name: {}, argument dir: {}".format(file_name, dir)

Save the file (

Runing system.

Open terminal and go the that dir where is save file. then write

python "/home/saiful/Desktop/bird.jpg"

Hit enter


File Name: test, Argument dir: /home/saiful/Desktop/bird.jpg

Postgresql - change the size of a varchar column to lower length

I was facing the same problem trying to truncate a VARCHAR from 32 to 8 and getting the ERROR: value too long for type character varying(8). I want to stay as close to SQL as possible because I'm using a self-made JPA-like structure that we might have to switch to different DBMS according to customer's choices (PostgreSQL being the default one). Hence, I don't want to use the trick of altering System tables.

I ended using the USING statement in the ALTER TABLE:

USING substr("MyColumn", 1, 8)

As @raylu noted, ALTER acquires an exclusive lock on the table so all other operations will be delayed until it completes.

Android get image path from drawable as string

These all are ways:

String imageUri = "drawable://" + R.drawable.image;

Other ways I tested

Uri path = Uri.parse("android.resource://com.segf4ult.test/" + R.drawable.icon);
Uri otherPath = Uri.parse("android.resource://com.segf4ult.test/drawable/icon");

String path = path.toString();
String path = otherPath .toString();

How to create EditText accepts Alphabets only in android?

EditText state = (EditText) findViewById(;

                Pattern ps = Pattern.compile("^[a-zA-Z ]+$");
                Matcher ms = ps.matcher(state.getText().toString());
                boolean bs = ms.matches();
                if (bs == false) {
                    if (ErrorMessage.contains("invalid"))
                        ErrorMessage = ErrorMessage + "state,";
                        ErrorMessage = ErrorMessage + "invalid state,";


Cannot lower case button text in android studio

in XML Code
add this line android:textAllCaps="false" like bellow code

       ** android:textAllCaps="false" ** />


in Java code (programmatically)
add this line to your button setAllCaps(false)

Button btn = (Button) findViewById(;

Is there an alternative sleep function in C to milliseconds?

Yes - older POSIX standards defined usleep(), so this is available on Linux:

int usleep(useconds_t usec);


The usleep() function suspends execution of the calling thread for (at least) usec microseconds. The sleep may be lengthened slightly by any system activity or by the time spent processing the call or by the granularity of system timers.

usleep() takes microseconds, so you will have to multiply the input by 1000 in order to sleep in milliseconds.

usleep() has since been deprecated and subsequently removed from POSIX; for new code, nanosleep() is preferred:

#include <time.h>

int nanosleep(const struct timespec *req, struct timespec *rem);


nanosleep() suspends the execution of the calling thread until either at least the time specified in *req has elapsed, or the delivery of a signal that triggers the invocation of a handler in the calling thread or that terminates the process.

The structure timespec is used to specify intervals of time with nanosecond precision. It is defined as follows:

struct timespec {
    time_t tv_sec;        /* seconds */
    long   tv_nsec;       /* nanoseconds */

An example msleep() function implemented using nanosleep(), continuing the sleep if it is interrupted by a signal:

#include <time.h>
#include <errno.h>    

/* msleep(): Sleep for the requested number of milliseconds. */
int msleep(long msec)
    struct timespec ts;
    int res;

    if (msec < 0)
        errno = EINVAL;
        return -1;

    ts.tv_sec = msec / 1000;
    ts.tv_nsec = (msec % 1000) * 1000000;

    do {
        res = nanosleep(&ts, &ts);
    } while (res && errno == EINTR);

    return res;

Should I use typescript? or I can just use ES6?

Decision tree between ES5, ES6 and TypeScript

Do you mind having a build step?

  • Yes - Use ES5
  • No - keep going

Do you want to use types?

  • Yes - Use TypeScript
  • No - Use ES6

More Details

ES5 is the JavaScript you know and use in the browser today it is what it is and does not require a build step to transform it into something that will run in today's browsers

ES6 (also called ES2015) is the next iteration of JavaScript, but it does not run in today's browsers. There are quite a few transpilers that will export ES5 for running in browsers. It is still a dynamic (read: untyped) language.

TypeScript provides an optional typing system while pulling in features from future versions of JavaScript (ES6 and ES7).

Note: a lot of the transpilers out there (i.e. babel, TypeScript) will allow you to use features from future versions of JavaScript today and exporting code that will still run in today's browsers.

Storing WPF Image Resources

Yes, it's the right way. You can use images in the Resource file using a path:

<StackPanel Orientation="Horizontal">
    <CheckBox  Content="{Binding Nname}" IsChecked="{Binding IsChecked}"/>
    <Image Source="E:\SWorking\SharePointSecurityApps\SharePointSecurityApps\SharePointSecurityApps.WPF\Images\sitepermission.png"/>
    <TextBlock Text="{Binding Path=Title}"></TextBlock>

Split large string in n-size chunks in JavaScript

I have written an extended function, so the chunk length can also be an array of numbers, like [1,3]

String.prototype.chunkString = function(len) {
    var _ret;
    if (this.length < 1) {
        return [];
    if (typeof len === 'number' && len > 0) {
        var _size = Math.ceil(this.length / len), _offset = 0;
        _ret = new Array(_size);
        for (var _i = 0; _i < _size; _i++) {
            _ret[_i] = this.substring(_offset, _offset = _offset + len);
    else if (typeof len === 'object' && len.length) {
        var n = 0, l = this.length, chunk, that = this;
        _ret = [];
        do {
            len.forEach(function(o) {
                chunk = that.substring(n, n + o);
                if (chunk !== '') {
                    n += chunk.length;
            if (n === 0) {
                return undefined; // prevent an endless loop when len = [0]
        } while (n < l);
    return _ret;

The code


will return:

[ '1', '234', '5', '678', '9', '012', '3' ]

How can I create C header files

  1. Open your favorite text editor
  2. Create a new file named whatever.h
  3. Put your function prototypes in it


Example whatever.h

int f(int a);

Note: include guards (preprocessor commands) added thanks to luke. They avoid including the same header file twice in the same compilation. Another possibility (also mentioned on the comments) is to add #pragma once but it is not guaranteed to be supported on every compiler.

Example whatever.c

#include "whatever.h"

int f(int a) { return a + 1; }

And then you can include "whatever.h" into any other .c file, and link it with whatever.c's object file.

Like this:


#include "whatever.h"

int main(int argc, char **argv)
    printf("%d\n", f(2)); /* prints 3 */
    return 0;

To compile it (if you use GCC):

$ gcc -c whatever.c -o whatever.o
$ gcc -c sample.c -o sample.o

To link the files to create an executable file:

$ gcc sample.o whatever.o -o sample

You can test sample:

$ ./sample

Can I set up HTML/Email Templates with ASP.NET?

If flexibility is one of your prerequisites, XSLT might be a good choice, which is completely supported by .NET framework and you would be able to even let the user edit those files. This article ( might be useful for a start (msdn has more info about it). As said by ScarletGarden NVelocity is another good choice but I do prefer XSLT for its " built-in" .NET framework support and platform agnostic.

Immediate exit of 'while' loop in C++

Yes, break will work. However, you may find that many programmers prefer not to use it when possible, rather, use a conditional if statement to perform anything else in the loop (thus, not performing it and exiting the loop cleanly)

Something like this will achieve what you're looking for, without having to use a break.

while(choice!=99) {
    cin >> choice;
    if (choice != 99) {

NoClassDefFoundError in Java: com/google/common/base/Function

When I caught the exception java.lang.NoClassDefFoundError: com/google/common/base/Function it was caused by errors in Project Libraries.

Please check it in your project settings. For Intellij IDEA go to File - Project Structure and select Modules tab. All I needed to do to resolve this exception was re-adding the selenium library

Execute php file from another php

It's trying to run it as a shell script, which interprets your <?php token as bash, which is a syntax error. Just use include() or one of its friends:

For example, in a.php put:

print "one";
include 'b.php';
print "three";

In b.php put:

print "two";


eric@dev ~ $ php a.php

Converting string to Date and DateTime

Like we have date "07/May/2018" and we need date "2018-05-07" as mysql compatible

if (!empty($date)) {
    $timestamp = strtotime($date);
    if ($timestamp === FALSE) {
         $timestamp = strtotime(str_replace('/', '-', $date));
         $date = date('Y-m-d', $timestamp);

It works for me. enjoy :)

How to get a key in a JavaScript object by its value?

ES6+ One Liners

let key = Object.keys(obj).find(k=>obj[k]===value);

Return all keys with the value:

let keys = Object.keys(obj).filter(k=>obj[k]===value);

How to change the window title of a MATLAB plotting figure?

You need to set figure properties.

At the very beginning of the script, call

figure('name','something else')

Calling figure is a good thing, anyway, because without it, you always plot into the same window, and sometimes you may want to compare two windows side-by-side.

Alternatively, you can store the figure's handle by calling

figH = figure;

so that you can later change the figure properties to your liking (the 'numberTitle' property setting eliminates the "figure X" text)

set(figH,'Name','something else','NumberTitle','off')

Have a look at the figure properties in the MATLAB documentation to see what else you can change if you want.

Check if an excel cell exists on another worksheet in a column - and return the contents of a different column

You can use following formulas.

For Excel 2007 or later:


For Excel 2003:

=IF(ISERROR(MATCH(D3,List!A:A, 0)), "No Match", VLOOKUP(D3,List!A:C,3,FALSE))

Note, that

  • I'm using List!A:C in VLOOKUP and returns value from column ? 3
  • I'm using 4th argument for VLOOKUP equals to FALSE, in that case VLOOKUP will only find an exact match, and the values in the first column of List!A:C do not need to be sorted (opposite to case when you're using TRUE).

Change the location of the ~ directory in a Windows install of Git Bash

I'd share what I did, which works not only for Git, but MSYS/MinGW as well.

The HOME environment variable is not normally set for Windows applications, so creating it through Windows did not affect anything else. From the Computer Properties (right-click on Computer - or whatever it is named - in Explorer, and select Properties, or Control Panel -> System and Security -> System), choose Advanced system settings, then Environment Variables... and create a new one, HOME, and assign it wherever you like.

If you can't create new environment variables, the other answer will still work. (I went through the details of how to create environment variables precisely because it's so dificult to find.)

How to initialize a JavaScript Date to a particular time zone

Try using ctoc from npm.

It has got simple functionality to change timezones (most timezones around 400) and all custom formats u want it to display.

What does the 'standalone' directive mean in XML?

The standalone declaration is a way of telling the parser to ignore any markup declarations in the DTD. The DTD is thereafter used for validation only.

As an example, consider the humble <img> tag. If you look at the XHTML 1.0 DTD, you see a markup declaration telling the parser that <img> tags must be EMPTY and possess src and alt attributes. When a browser is going through an XHTML 1.0 document and finds an <img> tag, it should notice that the DTD requires src and alt attributes and add them if they are not present. It will also self-close the <img> tag since it is supposed to be EMPTY. This is what the XML specification means by "markup declarations can affect the content of the document." You can then use the standalone declaration to tell the parser to ignore these rules.

Whether or not your parser actually does this is another question, but a standards-compliant validating parser (like a browser) should.

Note that if you do not specify a DTD, then the standalone declaration "has no meaning," so there's no reason to use it unless you also specify a DTD.

What does the "no version information available" error from linux dynamic linker mean?

How are you compiling your app? What compiler flags?

In my experience, when targeting the vast realm of Linux systems out there, build your packages on the oldest version you are willing to support, and because more systems tend to be backwards compatible, your app will continue to work. Actually this is the whole reason for library versioning - ensuring backward compatibility.

Find all CSV files in a directory using Python

I had to get csv files that were in subdirectories, therefore, using the response from tchlpr I modified it to work best for my use case:

import os
import glob

os.chdir( '/path/to/main/dir' )
result = glob.glob( '*/**.csv' )
print( result )

CSS3 Transition not working

A general answer for a general question... Transitions can't animate properties that are auto. If you have a transition not working, check that the starting value of the property is explicitly set. (For example, to make a node collapse, when it's height is auto and must stay that way, put the transition on max-height instead. Give max-height a sensible initial value, then transition it to 0)

How to install latest version of git on CentOS 7.x/6.x

It can be very confusing, and dangerous, to replace the upstream base repositories with add-on repositories without considerable testing and thought. RPMforge, in particularly, is effectively moribund and is not getting updates.

I personally publish tools for building git 2.4, wrapped as an alternatively named "git24" package, at Feel free to access and fork those if you want packages distinguished from the standard system packages, much as "samba" and "samba4" packages are differentiated.

How do I copy a string to the clipboard?

You can use module clipboard. Its simple and extremely easy to use. Works with Mac, Windows, & Linux.
Note: Its an alternative of pyperclip

After installing, import it:

import clipboard

Then you can copy like this:

clipboard.copy("This is copied")

You can also paste the copied text:


What is the => assignment in C# in a property signature

What you're looking at is an expression-bodied member not a lambda expression.

When the compiler encounters an expression-bodied property member, it essentially converts it to a getter like this:

public int MaxHealth
        return Memory[Address].IsValid ? Memory[Address].Read<int>(Offs.Life.MaxHp) : 0;

(You can verify this for yourself by pumping the code into a tool called TryRoslyn.)

Expression-bodied members - like most C# 6 features - are just syntactic sugar. This means that they don’t provide functionality that couldn't otherwise be achieved through existing features. Instead, these new features allow a more expressive and succinct syntax to be used

As you can see, expression-bodied members have a handful of shortcuts that make property members more compact:

  • There is no need to use a return statement because the compiler can infer that you want to return the result of the expression
  • There is no need to create a statement block because the body is only one expression
  • There is no need to use the get keyword because it is implied by the use of the expression-bodied member syntax.

I have made the final point bold because it is relevant to your actual question, which I will answer now.

The difference between...

// expression-bodied member property
public int MaxHealth => x ? y:z;


// field with field initializer
public int MaxHealth = x ? y:z;

Is the same as the difference between...

public int MaxHealth
        return x ? y:z;


public int MaxHealth = x ? y:z;

Which - if you understand properties - should be obvious.

Just to be clear, though: the first listing is a property with a getter under the hood that will be called each time you access it. The second listing is is a field with a field initializer, whose expression is only evaluated once, when the type is instantiated.

This difference in syntax is actually quite subtle and can lead to a "gotcha" which is described by Bill Wagner in a post entitled "A C# 6 gotcha: Initialization vs. Expression Bodied Members".

While expression-bodied members are lambda expression-like, they are not lambda expressions. The fundamental difference is that a lambda expression results in either a delegate instance or an expression tree. Expression-bodied members are just a directive to the compiler to generate a property behind the scenes. The similarity (more or less) starts and end with the arrow (=>).

I'll also add that expression-bodied members are not limited to property members. They work on all these members:

  • Properties
  • Indexers
  • Methods
  • Operators

Added in C# 7.0

However, they do not work on these members:

  • Nested Types
  • Events
  • Fields

CentOS: Copy directory to another directory

For copy directory use following command

cp -r source    Destination

For example

cp -r  /home/hasan   /opt 

For copy file use command without -r

cp   /home/file    /home/hasan/

How do I make a Docker container start automatically on system boot?

This is what crontab is for:

@reboot sleep 10 ; docker start <container name> 2>&1 | /usr/bin/logger -t 'docker start'

Access your user crontab by crontab -e or show it with crontab -l or edit your system crontab at /etc/crontab

Set value for particular cell in pandas DataFrame using index

Soo, your question to convert NaN at ['x',C] to value 10

the answer is..


alternative code is

df.loc['C', 'x']=10

Invoking a static method using reflection

// String.class here is the parameter type, that might not be the case with you
Method method = clazz.getMethod("methodName", String.class);
Object o = method.invoke(null, "whatever");

In case the method is private use getDeclaredMethod() instead of getMethod(). And call setAccessible(true) on the method object.

How to sort a dataFrame in python pandas by two or more columns?

For large dataframes of numeric data, you may see a significant performance improvement via numpy.lexsort, which performs an indirect sort using a sequence of keys:

import pandas as pd
import numpy as np


df1 = pd.DataFrame(np.random.randint(1, 5, (10,2)), columns=['a','b'])
df1 = pd.concat([df1]*100000)

def pdsort(df1):
    return df1.sort_values(['a', 'b'], ascending=[True, False])

def lex(df1):
    arr = df1.values
    return pd.DataFrame(arr[np.lexsort((-arr[:, 1], arr[:, 0]))])

assert (pdsort(df1).values == lex(df1).values).all()

%timeit pdsort(df1)  # 193 ms per loop
%timeit lex(df1)     # 143 ms per loop

One peculiarity is that the defined sorting order with numpy.lexsort is reversed: (-'b', 'a') sorts by series a first. We negate series b to reflect we want this series in descending order.

Be aware that np.lexsort only sorts with numeric values, while pd.DataFrame.sort_values works with either string or numeric values. Using np.lexsort with strings will give: TypeError: bad operand type for unary -: 'str'.

Java 8 stream map on entry set

Please make the following part of the Collectors API:

<K, V> Collector<? super Map.Entry<K, V>, ?, Map<K, V>> toMap() {
  return Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue);

How can I quantify difference between two images?

You can compare two images using functions from PIL.

import Image
import ImageChops

im1 ="splash.png")
im2 ="splash2.png")

diff = ImageChops.difference(im2, im1)

The diff object is an image in which every pixel is the result of the subtraction of the color values of that pixel in the second image from the first image. Using the diff image you can do several things. The simplest one is the diff.getbbox() function. It will tell you the minimal rectangle that contains all the changes between your two images.

You can probably implement approximations of the other stuff mentioned here using functions from PIL as well.

What does ':' (colon) do in JavaScript?

That's JSON, or JavaScript Object Notation. It's a quick way of describing an object, or a hash map. The thing before the colon is the property name, and the thing after the colon is its value. So in this example, there's a property "r", whose value is whatever's in the variable r. Same for t.

Sorting objects by property values

With ES6 arrow functions it will be like this:

//Let's say we have these cars
let cars = [ { brand: 'Porsche', top_speed: 260 },
  { brand: 'Benz', top_speed: 110 },
  { brand: 'Fiat', top_speed: 90 },
  { brand: 'Aston Martin', top_speed: 70 } ]

Array.prototype.sort() can accept a comparator function (here I used arrow notation, but ordinary functions work the same):

let sortedByBrand = [].sort((first, second) => first.brand > second.brand)

// [ { brand: 'Aston Martin', top_speed: 70 },
//   { brand: 'Benz', top_speed: 110 },
//   { brand: 'Fiat', top_speed: 90 },
//   { brand: 'Porsche', top_speed: 260 } ]

The above approach copies the contents of cars array into a new one and sorts it alphabetically based on brand names. Similarly, you can pass a different function:

let sortedBySpeed =[].sort((first, second) => first.top_speed > second.top_speed)

//[ { brand: 'Aston Martin', top_speed: 70 },
//  { brand: 'Fiat', top_speed: 90 },
//  { brand: 'Benz', top_speed: 110 },
//  { brand: 'Porsche', top_speed: 260 } ]

If you don't mind mutating the orginal array cars.sort(comparatorFunction) will do the trick.

How to set the background image of a html 5 canvas to .png image

You can use this plugin, but for printing purpose i have added some code like <button onclick="window.print();">Print</button> and for saving image <button onclick="savePhoto();">Save Picture</button>

     function savePhoto() {
     var canvas = document.getElementById("canvas");
     var img    = canvas.toDataURL("image/png");
     window.location = img;}

checkout this plugin

Getting Textarea Value with jQuery

try this:

<a id="send-thoughts" href="">Click</a>
<textarea id="message"></textarea>
<!--<textarea id="#message"></textarea>-->

            jQuery("a#send-thoughts").click(function() {
                //var thought = jQuery("textarea#message").val();
                var thought = $("#message").val();

Execute command on all files in a directory

i think the simple solution is:

sh /dir/* > ./result.txt

pull/push from multiple remote locations

add an alias to global gitconfig(/home/user/.gitconfig) with below command.

git config --global alias.pushall '!f(){ for var in $(git remote show); do echo "pushing to $var"; git push $var; done; }; f'

Once you commit code, we say

git push

to push to origin by default. After above alias, we can say

git pushall

and code will be updated to all remotes including origin remote.

S3 limit to objects in a bucket

There are no limits to the number of objects you can store in your S3 bucket. AWS claims it to have unlimited storage. However, there are some limitations -

  1. By default, customers can provision up to 100 buckets per AWS account. However, you can increase your Amazon S3 bucket limit by visiting AWS Service Limits.
  2. An object can be 0 bytes to 5TB.
  3. The largest object that can be uploaded in a single PUT is 5 gigabytes
  4. For objects larger than 100 megabytes, customers should consider using the Multipart Upload capability.

That being said if you really have a lot of objects to be stored in S3 bucket consider randomizing your object name prefix to improve performance.

When your workload is a mix of request types, introduce some randomness to key names by adding a hash string as a prefix to the key name. By introducing randomness to your key names the I/O load will be distributed across multiple index partitions. For example, you can compute an MD5 hash of the character sequence that you plan to assign as the key and add 3 or 4 characters from the hash as a prefix to the key name.

More details -

-- As of June 2018

Scroll to bottom of div with Vue.js

In the related question you posted, we already have a way to achieve that in plain javascript, so we only need to get the js reference to the dom node we want to scroll.

The ref attribute can be used to declare reference to html elements to make them available in vue's component methods.

Or, if the method in the component is a handler for some UI event, and the target is related to the div you want to scroll in space, you can simply pass in the event object along with your wanted arguments, and do the scroll like scroll(

Predicate Delegates in C#

The predicate-based searching methods allow a method delegate or lambda expression to decide whether a given element is a “match.” A predicate is simply a delegate accepting an object and returning true or false: public delegate bool Predicate (T object);

   static void Main()
            string[] names = { "Lukasz", "Darek", "Milosz" };
            string match1 = Array.Find(names, delegate(string name) { return name.Contains("L"); });
            string match2 = Array.Find(names, delegate(string name) { return name.Contains("L"); });
            string match3 = Array.Find(names, x => x.Contains("L"));

            Console.WriteLine(match1 + " " + match2 + " " + match3);     // Lukasz Lukasz Lukasz
        static bool ContainsL(string name) { return name.Contains("L"); }

Find duplicate records in MySQL

    Find duplicate Records:

    Suppose we have table : Student 
    student_id int
    student_name varchar
    | student_id | student_name        |
    |        101 | usman               |
    |        101 | usman               |
    |        101 | usman               |
    |        102 | usmanyaqoob         |
    |        103 | muhammadusmanyaqoob |
    |        103 | muhammadusmanyaqoob |

    Now we want to see duplicate records
    Use this query:

   select student_name,student_id ,count(*) c from student group by student_id,student_name having c>1;

| student_name        | student_id | c |
| usman               |        101 | 3 |
| muhammadusmanyaqoob |        103 | 2 |

Why does foo = filter(...) return a <filter object>, not a list?

From the documentation

Note that filter(function, iterable) is equivalent to [item for item in iterable if function(item)]

In python3, rather than returning a list; filter, map return an iterable. Your attempt should work on python2 but not in python3

Clearly, you are getting a filter object, make it a list.

shesaid = list(filter(greetings(), ["hello", "goodbye"]))

Creating temporary files in Android

For temporary internal files their are 2 options


File file; 
file = File.createTempFile(filename, null, this.getCacheDir());


File file
file = new File(this.getCacheDir(), filename);

Both options adds files in the applications cache directory and thus can be cleared to make space as required but option 1 will add a random number on the end of the filename to keep files unique. It will also add a file extension which is .tmp by default, but it can be set to anything via the use of the 2nd parameter. The use of the random number means despite specifying a filename it doesn't stay the same as the number is added along with the suffix/file extension (.tmp by default) e.g you specify your filename as internal_file and comes out as internal_file1456345.tmp. Whereas you can specify the extension you can't specify the number that is added. You can however find the filename it generates via file.getName();, but you would need to store it somewhere so you can use it whenever you wanted for example to delete or read the file. Therefore for this reason I prefer the 2nd option as the filename you specify is the filename that is created.

'nuget' is not recognized but other nuget commands working

In [Package Manager Console] try the below

Install-Package NuGet.CommandLine

What does "hashable" mean in Python?

All the answers here have good working explanation of hashable objects in python, but I believe one needs to understand the term Hashing first.

Hashing is a concept in computer science which is used to create high performance, pseudo random access data structures where large amount of data is to be stored and accessed quickly.

For example, if you have 10,000 phone numbers, and you want to store them in an array (which is a sequential data structure that stores data in contiguous memory locations, and provides random access), but you might not have the required amount of contiguous memory locations.

So, you can instead use an array of size 100, and use a hash function to map a set of values to same indices, and these values can be stored in a linked list. This provides a performance similar to an array.

Now, a hash function can be as simple as dividing the number with the size of the array and taking the remainder as the index.

For more detail refer to

Here is another good reference:

Concatenate two JSON objects

okay, you can do this in one line of code. you'll need json2.js for this (you probably already have.). the two json objects here are unparsed strings.

json1 = '[{"foo":"bar"},{"bar":"foo"},{"name":"craig"}]';

json2 = '[{"foo":"baz"},{"bar":"fob"},{"name":"george"}]';

concattedjson = JSON.stringify(JSON.parse(json1).concat(JSON.parse(json2)));

AngularJS $http-post - convert binary to excel file and download

There is no way (to my knowledge) to trigger the download window in your browser from Javascript. The only way to do it is to redirect the browser to a url that streams the file to the browser.

If you can modify your REST service, you might be able to solve it by changing so the POST request doesn't respond with the binary file, but with a url to that file. That'll get you the url in Javascript instead of the binary data, and you can redirect the browser to that url, which should prompt the download without leaving the original page.

CSS background image alt attribute

As mentioned in other answers, there is no (supported) alt attribute for a div tag only for the img tag.

The real question is why you need to add the alt attribute to all background images for the site? Based on this answer, it will help you determine which route to take in your approach.

Visual/Textual: If you are simply attempting to add a textual fall back for the user if the image fails to load, simply use the title attribute. Most browsers will provide a visual tool tip(message box) when a user hovers over the image, and if the image is not loaded for whatever reason, it behaves the same as an alt attribute presenting text when image fails. This technique still allows for the site to speed up load times by keeping images set to backgrounds.

Screen Readers: The middle of the road option, this varies because technically keeping your images as backgrounds and using the title attribute approach should work as hinted above, "Audio user agents may speak the title information in a similar context." However this is not guaranteed to work in all cases, including some readers may ignore it all together. If you end up opting for this approach, you can also try adding in aria-labels to help ensure screen readers pick these up.

SEO/Search Engines: Here is the big one, if you were like me, you added your background images, all was good. Then months later the customer(or maybe yourself) realized that you are missing out on some prime SEO gold by not having alt's for your images. Keep in mind, the title attribute does not have any weight on search engines, from my research and as mentioned in an article here: So if you are aiming for SEO, then you will need to have an img tag with the alt attribute. One possible approach is to just load very small actual images on the site with alt attributes, this way you get all the SEO and don't have to readjust the existing CSS in place. However this may lead to additional load time depending on the size and google does indeed look at the images path when indexing. In short if you are going this route, just accept what has to be done and include the actual images instead of using backgrounds.

Predict() - Maybe I'm not understanding it

First, you want to use

model <- lm(Total ~ Coupon, data=df)

not model <-lm(df$Total ~ df$Coupon, data=df).

Second, by saying lm(Total ~ Coupon), you are fitting a model that uses Total as the response variable, with Coupon as the predictor. That is, your model is of the form Total = a + b*Coupon, with a and b the coefficients to be estimated. Note that the response goes on the left side of the ~, and the predictor(s) on the right.

Because of this, when you ask R to give you predicted values for the model, you have to provide a set of new predictor values, ie new values of Coupon, not Total.

Third, judging by your specification of newdata, it looks like you're actually after a model to fit Coupon as a function of Total, not the other way around. To do this:

model <- lm(Coupon ~ Total, data=df)
new.df <- data.frame(Total=c(79037022, 83100656, 104299800))
predict(model, new.df)

Error when creating a new text file with python?

If the file does not exists, open(name,'r+') will fail.

You can use open(name, 'w'), which creates the file if the file does not exist, but it will truncate the existing file.

Alternatively, you can use open(name, 'a'); this will create the file if the file does not exist, but will not truncate the existing file.

Check if an element is present in an array

In lodash you can use _.includes (which also aliases to _.contains)

You can search the whole array:

_.includes([1, 2, 3], 1); // true

You can search the array from a starting index:

_.includes([1, 2, 3], 1, 1);  // false (begins search at index 1)

Search a string:

_.includes('pebbles', 'eb');  // true (string contains eb)

Also works for checking simple arrays of objects:

_.includes({ 'user': 'fred', 'age': 40 }, 'fred');    // true
_.includes({ 'user': 'fred', 'age': false }, false);  // true

One thing to note about the last case is it works for primitives like strings, numbers and booleans but cannot search through arrays or objects

_.includes({ 'user': 'fred', 'age': {} }, {});   // false
_.includes({ 'user': [1,2,3], 'age': {} }, 3);   // false

Update some specific field of an entity in android Room

after trying to fix a similar problem my self, where I had changed from @PrimaryKey(autoGenerate = true) to int UUID, I couldn't find how to write my migration so I changed the table name, it's an easy fix, and ok if you working with a personal/small app

How to use GROUP_CONCAT in a CONCAT in MySQL


Constraint Layout Vertical Align Center

It's possible to set the center aligned view as an anchor for other views. In the example below "@+id/stat_2" centered horizontally in parent and it serves as an anchor for other views in this layout.

< xmlns:android=""

        app:layout_constraintEnd_toStartOf="@+id/divider_1" />

        app:layout_constraintEnd_toEndOf="@+id/stat_1" />

        app:layout_constraintBottom_toBottomOf="@+id/stat_detail_2" />

        app:layout_constraintBottom_toBottomOf="parent" />

        android:text="Calories Burned"
        app:layout_constraintEnd_toEndOf="@+id/stat_2" />

        app:layout_constraintTop_toTopOf="@+id/stat_2" />

        app:layout_constraintStart_toEndOf="@+id/divider_2" />

        app:layout_constraintEnd_toEndOf="@+id/stat_3" />


Here's how it works on smallest smartphone (3.7 480x800 Nexus One) vs largest smartphone (5.5 1440x2560 Pixel XL)

Result view

Entity Framework 6 GUID as primary key: Cannot insert the value NULL into column 'Id', table 'FileStore'; column does not allow nulls

If you do Code-First and already have a Database:

public override void Up()
    AlterColumn("dbo.MyTable","Id", c =>  c.Guid(nullable: false, identity: true, defaultValueSql: "newsequentialid()"));

Syntax for if/else condition in SCSS mixin

You could default the parameter to null or false.
This way, it would be shorter to test if a value has been passed as parameter.

@mixin clearfix($width: null) {

  @if not ($width) {

    // if width is not passed, or empty do this

  } @else {

    display: inline-block;
    width: $width;


Convert Dictionary to JSON in Swift

My answer for your question is below

let dict = ["0": "ArrayObjectOne", "1": "ArrayObjecttwo", "2": "ArrayObjectThree"]

var error : NSError?

let jsonData = try! NSJSONSerialization.dataWithJSONObject(dict, options: NSJSONWritingOptions.PrettyPrinted)

let jsonString = NSString(data: jsonData, encoding: String.Encoding.utf8.rawValue)! as String


Answer is

  "0" : "ArrayObjectOne",
  "1" : "ArrayObjecttwo",
  "2" : "ArrayObjectThree"

new DateTime() vs default(DateTime)

The answer is no. Keep in mind that in both cases, mdDate.Kind = DateTimeKind.Unspecified.

Therefore it may be better to do the following:

DateTime myDate = new DateTime(1, 1, 1, 0, 0, 0, DateTimeKind.Utc);

The myDate.Kind property is readonly, so it cannot be changed after the constructor is called.

How do I save JSON to local text file

Here is a solution on pure js. You can do it with html5 saveAs. For example this lib could be helpful:
Look at the demo:
P.S. There is no information about json save, but you can do it changing file type to "application/json" and format to .json

How to combine results of two queries into a single dataset

How about,

        null col3, 
        null col4 
    from Table1
union all
        null col1, 
        null col2,
        col4 col3, 
        col5 col4 
    from Table2;

event.preventDefault() vs. return false

Generally, your first option (preventDefault()) is the one to take, but you have to know what context you're in and what your goals are.

Fuel Your Coding has a great article on return false; vs event.preventDefault() vs event.stopPropagation() vs event.stopImmediatePropagation().

SQLite in Android How to update a specific row

public long fillDataTempo(String table){
    String[] table = new String[1];
    tabela[0] = table; 
    ContentValues args = new ContentValues();
    args.put(DBOpenHelper.DATA_HORA, new Date().toString());
    args.put(DBOpenHelper.NOME_TABELA, nome_tabela);
    return db.update(DATABASE_TABLE, args, STRING + " LIKE ?" ,tabela);

Sort dataGridView columns in C# ? (Windows Form)


Angularjs - simple form submit

WARNING This is for Angular 1.x

If you are looking for Angular (v2+, currently version 8), try this answer or the official guide.


I have rewritten your JS fiddle here:

<div ng-app="myApp">

    <form name="saveTemplateData" action="#" ng-controller="FormCtrl" ng-submit="submitForm()">

        First name:    <br/><input type="text" name="form.firstname">    

        Email Address: <br/><input type="text" ng-model="form.emailaddress"> 

        <textarea rows="3" cols="25">
          Describe your reason for submitting this form ... 

        <input type="radio" ng-model="form.gender" value="female" />Female
        <input type="radio" ng-model="form.gender" value="male" />Male 

        <input type="checkbox" ng-model="form.member" value="true"/> Already a member
        <input type="checkbox" ng-model="form.member" value="false"/> Not a member

        <input type="file" ng-model="form.file_profile" id="file_profile">

        <input type="file" ng-model="form.file_avatar" id="file_avatar">

        <input type="submit">

Here I'm using lots of angular directives(ng-controller, ng-model, ng-submit) where you were using basic html form submission. Normally all alternatives to "The angular way" work, but form submission is intercepted and cancelled by Angular to allow you to manipulate the data before submission

BUT the JSFiddle won't work properly as it doesn't allow any type of ajax/http post/get so you will have to run it locally.

For general advice on angular form submission see the cookbook examples

UPDATE The cookbook is gone. Instead have a look at the 1.x guide for for form submission

The cookbook for angular has lots of sample code which will help as the docs aren't very user friendly.

Angularjs changes your entire web development process, don't try doing things the way you are used to with JQuery or regular html/js, but for everything you do take a look around for some sample code, as there is almost always an angular alternative.

How to allow access outside localhost

run command

ng serve --host= --disable-host-check

this will disable host check and allow to access from outside(instead of localhost) with IP address

What is the maximum length of a String in PHP? says:

Note: As of PHP 7.0.0, there are no particular restrictions regarding the length of a string on 64-bit builds. On 32-bit builds and in earlier versions, a string can be as large as up to 2GB (2147483647 bytes maximum)

In PHP 5.x, strings were limited to 231-1 bytes, because internal code recorded the length in a signed 32-bit integer.

You can slurp in the contents of an entire file, for instance using file_get_contents()

However, a PHP script has a limit on the total memory it can allocate for all variables in a given script execution, so this effectively places a limit on the length of a single string variable too.

This limit is the memory_limit directive in the php.ini configuration file. The memory limit defaults to 128MB in PHP 5.2, and 8MB in earlier releases.

If you don't specify a memory limit in your php.ini file, it uses the default, which is compiled into the PHP binary. In theory you can modify the source and rebuild PHP to change this default value.

If you specify -1 as the memory limit in your php.ini file, it stop checking and permits your script to use as much memory as the operating system will allocate. This is still a practical limit, but depends on system resources and architecture.

Re comment from @c2:

Here's a test:


// limit memory usage to 1MB 
ini_set('memory_limit', 1024*1024);

// initially, PHP seems to allocate 768KB for basic operation
printf("memory: %d\n",  memory_get_usage(true));

$str = str_repeat('a',  255*1024);
echo "Allocated string of 255KB\n";

// now we have allocated all of the 1MB of memory allowed
printf("memory: %d\n",  memory_get_usage(true));

// going over the limit causes a fatal error, so no output follows
$str = str_repeat('a',  256*1024);
echo "Allocated string of 256KB\n";
printf("memory: %d\n",  memory_get_usage(true));

HTTP 400 (bad request) for logical error, not malformed request syntax

In my case:

I am getting 400 bad request because I set content-type wrongly. I changed content type then able to get response successfully.

Before (Issue):

ClientResponse response = Client.create().resource(requestUrl).queryParam("noOfDates", String.valueOf(limit))
                .header(SecurityConstants.AUTHORIZATION, formatedToken).
header("Content-Type", "\"application/json\"").get(ClientResponse.class);

After (Fixed):

ClientResponse response = Client.create().resource(requestUrl).queryParam("noOfDates", String.valueOf(limit))
                .header(SecurityConstants.AUTHORIZATION, formatedToken).
header("Content-Type", "\"application/x-www-form-urlencoded\"").get(ClientResponse.class);

How to overload functions in javascript?

I am using a bit different overloading approach based on arguments number. However i believe John Fawcett's approach is also good. Here the example, code based on John Resig's (jQuery's Author) explanations.

// o = existing object, n = function name, f = function.
    function overload(o, n, f){
        var old = o[n];
        o[n] = function(){
            if(f.length == arguments.length){
                return f.apply(this, arguments);
            else if(typeof o == 'function'){
                return old.apply(this, arguments);


var obj = {};
overload(obj, 'function_name', function(){ /* what we will do if no args passed? */});
overload(obj, 'function_name', function(first){ /* what we will do if 1 arg passed? */});
overload(obj, 'function_name', function(first, second){ /* what we will do if 2 args passed? */});
overload(obj, 'function_name', function(first,second,third){ /* what we will do if 3 args passed? */});
//... etc :)

Clang vs GCC for my Linux Development project

As of right now, GCC has much better and more complete support for C++11 features than Clang. Also, the code generator for GCC performs better optimisation than the one in Clang (in my experience, I have not seen any exhaustive tests).

On the other hand, Clang often compiles code more quickly than GCC, and produces better error messages when there is something wrong with your code.

The choice of which one to use really depends on what things are important to you. I value C++11 support and code generation quality more than I value convenience of compilation. Because of this, I use GCC. For you, the trade-offs could be different.

How to remove a row from JTable?

In order to remove a row from a JTable, you need to remove the target row from the underlying TableModel. If, for instance, your TableModel is an instance of DefaultTableModel, you can remove a row by doing the following:


Laravel: How to Get Current Route Name? (v5 ... v7)

Request::path(); is better, and remember to use Request;

Detect click event inside iframe

The tinymce API takes care of many events in the editors iframe. I strongly suggest to use them. Here is an example for the click handler

// Adds an observer to the onclick event using tinyMCE.init
   setup : function(ed) {
      ed.onClick.add(function(ed, e) {
           console.debug('Iframe clicked:' +;

How can I pass a parameter to a t-sql script?

Two options save vijay.sql

execute immediate 
SELECT wk.*,bbc.distance_km ,NVL(bbc.tactical_broadband_offer,0) tactical_broadband_offer ,
FROM   spineowner.pop_wkly_refresh_20100201 wk,
       dms_bb_coverage_102009 bbc,
       dms_select_executive_group sel,
       DMS_RESIGN_CAMPAIGN_26052009 res,
       DMS_PRIORITY_CLUB pclub
WHERE  wk.mpn = bbc.mpn(+)
AND    wk.mpn = sel.mpn (+)
AND    wk.mpn = res.mpn (+)
AND    wk.mpn = pclub.mpn (+)'

The above will generate table names automatically based on sysdate. If you still need to pass as variable, then save vijay.sql as

execute immediate 
SELECT wk.*,bbc.distance_km ,NVL(bbc.tactical_broadband_offer,0) tactical_broadband_offer ,
FROM   spineowner.pop_wkly_refresh_20100201 wk,
       dms_bb_coverage_102009 bbc,
       dms_select_executive_group sel,
       DMS_RESIGN_CAMPAIGN_26052009 res,
       DMS_PRIORITY_CLUB pclub
WHERE  wk.mpn = bbc.mpn(+)
AND    wk.mpn = sel.mpn (+)
AND    wk.mpn = res.mpn (+)
AND    wk.mpn = pclub.mpn (+)'

and then run as sqlplus -s username/password @vijay.sql '20100101'

How to push changes to github after jenkins build completes?

The git checkout master of the answer by Woland isn't needed. Instead use the "Checkout to specific local branch" in the "Additional Behaviors" section to set the "Branch name" to master.

The git commit -am "blah" is still needed.

Now you can use the "Git Publisher" under "Post-build Actions" to push the changes. Be sure to specify the "Branches" to push ("Branch to push" = master, "Target remote name" = origin).

"Merge Results" isn't needed.

req.query and req.param in ExpressJS

req.query will return a JS object after the query string is parsed.

/user?name=tom&age=55 - req.query would yield {name:"tom", age: "55"}

req.params will return parameters in the matched route. If your route is /user/:id and you make a request to /user/5 - req.params would yield {id: "5"}

req.param is a function that peels parameters out of the request. All of this can be found here.


If the verb is a POST and you are using bodyParser, then you should be able to get the form body in you function with req.body. That will be the parsed JS version of the POSTed form.

How to Solve Max Connection Pool Error

Before you begin to curse your application you need to check this:

  1. Is your application the only one using that instance of SQL Server. a. If the answer to that is NO then you need to investigate how the other applications are consuming resources on your SQl b. If the answer is yes then you must investigate your application.

  2. Run SQL Server Profiler and check what activity is happening in other applications (1a) using SQL Server and check your application as well (1b).

  3. If indeed your application is starved off of resources then you need to make farther investigations. For more read on this

How to properly seed random number generator

If your aim is just to generate a sting of random number then I think it's unnecessary to complicate it with multiple function calls or resetting seed every time.

The most important step is to call seed function just once before actually running rand.Init(x). Seed uses the provided seed value to initialize the default Source to a deterministic state. So, It would be suggested to call it once before the actual function call to pseudo-random number generator.

Here is a sample code creating a string of random numbers

package main 
import (

func main(){

    var s string
    for i:=0;i<10;i++{
    s+=fmt.Sprintf("%d ",rand.Intn(7))

The reason I used Sprintf is because it allows simple string formatting.

Also, In rand.Intn(7) Intn returns, as an int, a non-negative pseudo-random number in [0,7).

Git for beginners: The definitive practical guide

Seriously add the link featured in Tim's answer in the Stack Overflow post Setup Git Server with Msysgit on Windows.

It flawlessly told me how to setup Git on Windows with msysgit, and is an incredibly detailed article.

How to make an alert dialog fill 90% of screen size?

Above many of the answers are good but none of the worked for me fully. So i combined the answer from @nmr and got this one.

final Dialog d = new Dialog(getActivity());
        //  d.getWindow().setBackgroundDrawable(R.color.action_bar_bg);

        WindowManager wm = (WindowManager) getActivity().getSystemService(Context.WINDOW_SERVICE); // for activity use context instead of getActivity()
        Display display = wm.getDefaultDisplay(); // getting the screen size of device
        Point size = new Point();
        int width = size.x - 20;  // Set your heights
        int height = size.y - 80; // set your widths

        WindowManager.LayoutParams lp = new WindowManager.LayoutParams();

        lp.width = width;
        lp.height = height;


HikariCP - connection is not available

I managed to fix it finally. The problem is not related to HikariCP. The problem persisted because of some complex methods in REST controllers executing multiple changes in DB through JPA repositories. For some reasons calls to these interfaces resulted in a growing number of "freezed" active connections, exhausting the pool. Either annotating these methods as @Transactional or enveloping all the logic in a single call to transactional service method seem to solve the problem.

Facebook Like-Button - hide count?

If you do overflow:hidden then keep in mind that it will also hide the comment box that comes up in XFBML version... after user likes it. So best if you do this...

/* make the like button smaller */
.fb_edge_widget_with_comment iframe
    width:47px !important;

/* but make the span that holds the comment box larger */
span.fb_edge_comment_widget.fb_iframe_widget iframe
    width:401px !important;

How to post JSON to PHP with curl

Normally the parameter -d is interpreted as form-encoded. You need the -H parameter:

curl -v -H "Content-Type: application/json" -X POST -d '{"screencast":{"subject":"tools"}}' \

System.web.mvc missing

Add the reference again from ./packages/Microsoft.AspNet.Mvc.[version]/lib/net45/System.Web.Mvc.dll

Hide/encrypt password in bash file to stop accidentally seeing it

Following line in above code is not working

DB_PASSWORD=$(eval echo ${DB_PASSWORD} | base64 --decode)

Correct line is:

DB_PASSWORD=`echo $PASSWORD|base64 -d`

And save the password in other file as PASSWORD.

Combine hover and click functions (jQuery)?

Use basic programming composition: create a method and pass the same function to click and hover as a callback.

var hoverOrClick = function () {
    // do something common

Second way: use bindon:

$('#target').on('click mouseover', function () {
    // Do something for both

jQuery('#target').bind('click mouseover', function () {
    // Do something for both

How do I call the base class constructor?

You do this in the initializer-list of the constructor of the subclass.

class Foo : public BaseClass {
    Foo() : BaseClass("asdf") {}

Base-class constructors that take arguments have to be called there before any members are initialized.

Why is semicolon allowed in this python snippet?

Python uses the ; as a separator, not a terminator. You can also use them at the end of a line, which makes them look like a statement terminator, but this is legal only because blank statements are legal in Python -- a line that contains a semicolon at the end is two statements, the second one blank.

What does "control reaches end of non-void function" mean?

Always build with at least minimal optimization. With -O0, all analysis that the compiler could use to determine that execution cannot reach the end of the function has been disabled. This is why you're seeing the warning. The only time you should ever use -O0 is for step-by-line debugging, which is usually not a good debugging approach anyway, but it's what most people who got started with MSVC learned on...

JSON and XML comparison

I found this article at digital bazaar really interesting. Quoting their quotations from Norm:

About JSON pros:

If all you want to pass around are atomic values or lists or hashes of atomic values, JSON has many of the advantages of XML: it’s straightforwardly usable over the Internet, supports a wide variety of applications, it’s easy to write programs to process JSON, it has few optional features, it’s human-legible and reasonably clear, its design is formal and concise, JSON documents are easy to create, and it uses Unicode. ...

About XML pros:

XML deals remarkably well with the full richness of unstructured data. I’m not worried about the future of XML at all even if its death is gleefully celebrated by a cadre of web API designers.

And I can’t resist tucking an "I told you so!" token away in my desk. I look forward to seeing what the JSON folks do when they are asked to develop richer APIs. When they want to exchange less well strucured data, will they shoehorn it into JSON? I see occasional mentions of a schema language for JSON, will other languages follow? ...

I personally agree with Norm. I think that most attacks to XML come from Web Developers for typical applications, and not really from integration developers. But that's my opinion! ;)

Certificate has either expired or has been revoked

rename your catalog, don't contain Decimal point & 0(zero).

like this, I solve it .

Javascript Uncaught Reference error Function is not defined

In JSFiddle, when you set the wrapping to "onLoad" or "onDomready", the functions you define are only defined inside that block, and cannot be accessed by outside event handlers.

Easiest fix is to change:

function something(...)


window.something = function(...)

How to pass variables from one php page to another without form?

check to make sure the variable is set. Then clean it before using it:


Otherwise, assign it a default value ($var='' is fine) to avoid the error you mentioned.

Missing artifact

You can also create a project repository. It's useful if more developers are working on the same project, and the library must be included in the project.

  • First, create a repository structure in your project's lib directory, and then copy the library into it. The library must have following name-format: <artifactId>-<version>.jar


  • Create pom file next to the library file, and put following information into it:

    <?xml version="1.0" encoding="UTF-8"?>
     <project xsi:schemaLocation="" xmlns=""
  • At this point, you should have this directory structure:

    <your_project_dir>/lib/com/microsoft/sqlserver/sqljdbc4/4.2/sqljdbc4-4.2.jar <your_project_dir>/lib/com/microsoft/sqlserver/sqljdbc4/4.2/sqljdbc4-4.2.pom

  • Go to your project's pom file and add new repository:

             <id>Project repository</id>
  • Finally, add a dependency on the library:


Update 2017-03-04

It seems like the library can be obtained from publicly available repository. @see nirmal's and Jacek Grzelaczyk's answers for more details.

Update 2020-11-04

Currently Maven has a convenient target install which allow you to deploy an existing package into a project / file repository without the need of creating POM files manually. It will generate those files for you.

mvn install:install-file \
    -Dfile=sqljdbc4.jar \ \
    -DartifactId=sqljdbc4 \
    -Dversion=4.2 \
    -Dpackaging=jar \

What is the difference between an Instance and an Object?

This answer may be seen as trite, but worrying about the differences between an instance and object is already trite city.

I think its best depicted in javascript:

let obj= {"poo":1} 
// "obj" is an object


Class Trash {
    constructor(){this.poo = 1;}

let i = new Trash();
// "i" is an instance

No Multiline Lambda in Python: Why not?

Look at the following:

map(multilambda x:
      return y
   , [1,2,3])

Is this a lambda returning (y, [1,2,3]) (thus map only gets one parameter, resulting in an error)? Or does it return y? Or is it a syntax error, because the comma on the new line is misplaced? How would Python know what you want?

Within the parens, indentation doesn't matter to python, so you can't unambiguously work with multilines.

This is just a simple one, there's probably more examples.

Can not deserialize instance of java.lang.String out of START_ARRAY token

The error is:

Can not deserialize instance of java.lang.String out of START_ARRAY token at [Source: line: 1, column: 1095] (through reference chain: JsonGen["platforms"])

In JSON, platforms look like this:

"platforms": [
        "platform": "iphone"
        "platform": "ipad"
        "platform": "android_phone"
        "platform": "android_tablet"

So try change your pojo to something like this:

private List platforms;

public List getPlatforms(){
    return this.platforms;

public void setPlatforms(List platforms){
    this.platforms = platforms;

EDIT: you will need change mobile_networks too. Will look like this:

private List mobile_networks;

public List getMobile_networks() {
    return mobile_networks;

public void setMobile_networks(List mobile_networks) {
    this.mobile_networks = mobile_networks;

List names of all tables in a SQL Server 2012 schema

SELECT AS [Schema], AS [Table]
FROM sys.schemas t1
INNER JOIN sys.tables t2
ON t2.schema_id = t1.schema_id

How to make a variadic macro (variable number of arguments)

C99 way, also supported by VC++ compiler.

#define FOO(fmt, ...) printf(fmt, ##__VA_ARGS__)

Script for rebuilding and reindexing the fragmented index?

I have found the following script is very good at maintaining indexes, you can have this scheduled to run nightly or whatever other timeframe you wish.

Send email from localhost running XAMMP in PHP using GMAIL mail server

Simplest way is to use PHPMailer and Gmail SMTP. The configuration would be like the below.

require 'PHPMailer/PHPMailerAutoload.php';
$mail = new PHPMailer;

$mail->Host = '';            
$mail->SMTPAuth = true;                     
$mail->Username = 'Email Address';          
$mail->Password = 'Email Account Password'; 
$mail->SMTPSecure = 'tls';               
$mail->Port = 587;                  

Example script and full source code can be found from here - How to Send Email from Localhost in PHP

Read from database and fill DataTable

Connection object is for illustration only. The DataAdapter is the key bit:

Dim strSql As String = "SELECT EmpCode,EmpID,EmpName FROM dbo.Employee"
Dim dtb As New DataTable
Using cnn As New SqlConnection(connectionString)
  Using dad As New SqlDataAdapter(strSql, cnn)
  End Using
End Using

AttributeError: 'module' object has no attribute

I experienced this error because the module was not actually imported. The code looked like this:

import a.b, a.c

# ...

something(a.d)  # My addition, which failed.

The last line resulted in an AttributeError. The cause was that I had failed to notice that the submodules of a (a.b and a.c) were explicitly imported, and assumed that the import statement actually imported a.

What precisely does 'Run as administrator' do?

Windows 7 requires that you intentionally ask for certain privileges so that a malicious program can't do bad things to you. If the free calculator you downloaded needed to be run as an administrator, you would know something is up. There are OS commands to elevate the privilege of your application (which will request confirmation from the user).

A good description can be found at:

Spring Data JPA find by embedded object property

According to me, Spring doesn't handle all the cases with ease. In your case the following should do the trick

Page<QueuedBook> findByBookIdRegion(Region region, Pageable pageable);  


Page<QueuedBook> findByBookId_Region(Region region, Pageable pageable);

However, it also depends on the naming convention of fields that you have in your @Embeddable class,

e.g. the following field might not work in any of the styles that mentioned above

private String cRcdDel;

I tried with both the cases (as follows) and it didn't work (it seems like Spring doesn't handle this type of naming conventions(i.e. to many Caps , especially in the beginning - 2nd letter (not sure about if this is the only case though)

Page<QueuedBook> findByBookIdCRcdDel(String cRcdDel, Pageable pageable); 


Page<QueuedBook> findByBookIdCRcdDel(String cRcdDel, Pageable pageable);

When I renamed column to

private String rcdDel;

my following solutions work fine without any issue:

Page<QueuedBook> findByBookIdRcdDel(String rcdDel, Pageable pageable); 


Page<QueuedBook> findByBookIdRcdDel(String rcdDel, Pageable pageable);

Sound alarm when code finishes

A bit more to your question.

I used gTTS package to generate audio from text and then play that audio using Playsound when I was learning webscraping and created a coursera downloader(only free courses).

text2speech = gTTS("Your course " + course_name +
                                " is downloaded to " + downloads + ". Check it fast.")"temp.mp3")
winsound.Beep(2500, 1000)

How to Convert unsigned char* to std::string in C++?

Here is the complete code

#include <bits/stdc++.h>

using namespace std;

typedef unsigned char BYTE;

int main() {
  //method 1;
  std::vector<BYTE> data = {'H','E','L','L','O','1','2','3'};
  //string constructor accepts only const char
  std::string s((const char*)&(data[0]), data.size());
  std::cout << s << std::endl;

  //method 2
  std::string s2(data.begin(),data.end());
  std::cout << s2 << std::endl;

  //method 3
  std::string s3(reinterpret_cast<char const*>(&data[0]), data.size()) ;
  std::cout << s3 << std::endl;
  return 0;

Netbeans - Error: Could not find or load main class

I had the same problem and I moved the project to a location where the path had no none-english letter and that fixed the problem

Mocking member variables of a class using Mockito

If you look closely at your code you'll see that the second property in your test is still an instance of Second, not a mock (you don't pass the mock to first in your code).

The simplest way would be to create a setter for second in First class and pass it the mock explicitly.

Like this:

public class First {

    Second second ;

    public First(){
        second = new Second();

    public String doSecond(){
        return second.doSecond();

    public void setSecond(Second second) {
        this.second = second;


class Second {

    public String doSecond(){
        return "Do Something";


public void testFirst(){
Second sec = mock(Second.class);
when(sec.doSecond()).thenReturn("Stubbed Second");

First first = new First();
assertEquals("Stubbed Second", first.doSecond());

Another would be to pass a Second instance as First's constructor parameter.

If you can't modify the code, I think the only option would be to use reflection:

public void testFirst(){
    Second sec = mock(Second.class);
    when(sec.doSecond()).thenReturn("Stubbed Second");

    First first = new First();
    Field privateField = PrivateObject.class.


    privateField.set(first, sec);

    assertEquals("Stubbed Second", first.doSecond());

But you probably can, as it's rare to do tests on code you don't control (although one can imagine a scenario where you have to test an external library cause it's author didn't :))

"The remote certificate is invalid according to the validation procedure." using Gmail SMTP server

I had the same error when i tried to send email using SmtpClient via proxy server (Usergate).

Verifies the certificate contained the address of the server, which is not equal to the address of the proxy server, hence the error. My solution: when an error occurs while checking the certificate, receive the certificate, export it and check.

public static bool RemoteServerCertificateValidationCallback(Object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        if (sslPolicyErrors == SslPolicyErrors.None)
            return true;

        // if got an cert auth error
        if (sslPolicyErrors != SslPolicyErrors.RemoteCertificateNameMismatch) return false;
        const string sertFileName = "smpthost.cer";

        // check if cert file exists
        if (File.Exists(sertFileName))
            var actualCertificate = X509Certificate.CreateFromCertFile(sertFileName);
            return certificate.Equals(actualCertificate);

        // export and check if cert not exists
        using (var file = File.Create(sertFileName))
            var cert = certificate.Export(X509ContentType.Cert);
            file.Write(cert, 0, cert.Length);
        var createdCertificate = X509Certificate.CreateFromCertFile(sertFileName);
        return certificate.Equals(createdCertificate);

Full code of my email sender class:

public class EmailSender
    private readonly SmtpClient _smtpServer;
    private readonly MailAddress _fromAddress;

    public EmailSender()
        ServicePointManager.ServerCertificateValidationCallback = RemoteServerCertificateValidationCallback;
        _smtpServer = new SmtpClient();

    public EmailSender(string smtpHost, int smtpPort, bool enableSsl, string userName, string password, string fromEmail, string fromName) : this()
        _smtpServer.Host = smtpHost;
        _smtpServer.Port = smtpPort;
        _smtpServer.UseDefaultCredentials = false;
        _smtpServer.EnableSsl = enableSsl;
        _smtpServer.Credentials = new NetworkCredential(userName, password);

        _fromAddress = new MailAddress(fromEmail, fromName);

    public bool Send(string address, string mailSubject, string htmlMessageBody,
        string fileName = null)
        return Send(new List<MailAddress> { new MailAddress(address) }, mailSubject, htmlMessageBody, fileName);

    public bool Send(List<MailAddress> addressList, string mailSubject, string htmlMessageBody,
        string fileName = null)
        var mailMessage = new MailMessage();
            if (_fromAddress != null)
                mailMessage.From = _fromAddress;

            foreach (var addr in addressList)

            mailMessage.SubjectEncoding = Encoding.UTF8;
            mailMessage.Subject = mailSubject;

            mailMessage.Body = htmlMessageBody;
            mailMessage.BodyEncoding = Encoding.UTF8;
            mailMessage.IsBodyHtml = true;

            if ((fileName != null) && (System.IO.File.Exists(fileName)))
                var attach = new Attachment(fileName, MediaTypeNames.Application.Octet);
                attach.ContentDisposition.CreationDate = System.IO.File.GetCreationTime(fileName);
                attach.ContentDisposition.ModificationDate = System.IO.File.GetLastWriteTime(fileName);
                attach.ContentDisposition.ReadDate = System.IO.File.GetLastAccessTime(fileName);
        catch (Exception e)
            // TODO lor error
            return false;
        return true;

    public static bool RemoteServerCertificateValidationCallback(Object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
    if (sslPolicyErrors == SslPolicyErrors.None)
        return true;

    // if got an cert auth error
    if (sslPolicyErrors != SslPolicyErrors.RemoteCertificateNameMismatch) return false;
    const string sertFileName = "smpthost.cer";

    // check if cert file exists
    if (File.Exists(sertFileName))
        var actualCertificate = X509Certificate.CreateFromCertFile(sertFileName);
        return certificate.Equals(actualCertificate);

    // export and check if cert not exists
    using (var file = File.Create(sertFileName))
        var cert = certificate.Export(X509ContentType.Cert);
        file.Write(cert, 0, cert.Length);
    var createdCertificate = X509Certificate.CreateFromCertFile(sertFileName);
    return certificate.Equals(createdCertificate);


How to get the entire document HTML as a string?


Difference between abstraction and encapsulation?

Encapsulation: Is hiding unwanted/un-expected/propriety implementation details from the actual users of object. e.g.

List<string> list = new List<string>();
list.Sort(); /* Here, which sorting algorithm is used and hows its 
implemented is not useful to the user who wants to perform sort, that's 
why its hidden from the user of list. */

Abstraction: Is a way of providing generalization and hence a common way to work with objects of vast diversity. e.g.

class Aeroplane : IFlyable, IFuelable, IMachine
{ // Aeroplane's Design says:
  // Aeroplane is a flying object
  // Aeroplane can be fueled
  // Aeroplane is a Machine
// But the code related to Pilot, or Driver of Aeroplane is not bothered 
// about Machine or Fuel. Hence,
// pilot code:
IFlyable flyingObj = new Aeroplane();
// fighter Pilot related code
IFlyable flyingObj2 = new FighterAeroplane();
// UFO related code 
IFlyable ufoObj = new UFO();
// **All the 3 Above codes are genaralized using IFlyable,
// Interface Abstraction**
// Fly related code knows how to fly, irrespective of the type of 
// flying object they are.

// Similarly, Fuel related code:
// Fueling an Aeroplane
IFuelable fuelableObj = new Aeroplane();
// Fueling a Car
IFuelable fuelableObj2 = new Car(); // class Car : IFuelable { }

// ** Fueling code does not need know what kind of vehicle it is, so far 
// as it can Fill Fuel**

fatal: ambiguous argument 'origin': unknown revision or path not in the working tree

If origin points to a bare repository on disk, this error can happen if that directory has been moved (even if you update the working copy's remotes). For example

$ mv /path/to/origin /somewhere/else
$ git remote set-url origin /somewhere/else
$ git diff origin/master
fatal: ambiguous argument 'origin': unknown revision or path not in the working tree.

Pulling once from the new origin solves the problem:

$ git stash
$ git pull origin master
$ git stash pop

deleting rows in numpy array

numpy provides a simple function to do the exact same thing: supposing you have a masked array 'a', calling will delete the rows containing a masked value. I guess this is much faster this way...

pass post data with window.location.href

Have you considered simply using Local/Session Storage? -or- Depending on the complexity of what you're building; you could even use indexDB.


Local storage and indexDB are not secure - so you want to avoid storing any sensitive / personal data (i.e names, addresses, emails addresses, DOB etc) in either of these.

Session Storage is a more secure option for anything sensitive, it's only accessible to the origin that set the items and also clears as soon as the browser / tab is closed.

IndexDB is a little more [but not much more] complicated and is a 30MB noSQL database built into every browser (but can be basically unlimited if the user opts in) -> next time you're using Google docs, open you DevTools -> application -> IndexDB and take a peak. [spoiler alert: it's encrypted].

Focusing on Local and Session Storage; these are both dead simple to use:

// To Set 
sessionStorage.setItem( 'key' , 'value' );

// e.g.
sessionStorage.setItem( 'formData' , { name: "Mr Manager", company: "Bluth's Frozen Bananas", ...  } );    

// Get The Data 
const fromData = sessionStorage.getItem( 'key' );     

// e.g. (after navigating to next location)
const fromData = sessionStorage.getItem( 'formData' );

// Remove 
sessionStorage.removeItem( 'key' );

// Remove _all_ saved data sessionStorage
sessionStorage.clear( ); 

If simple is not your thing -or- maybe you want to go off road and try a different approach all together -> you can probably use a shared web worker... y'know, just for kicks.

String.contains in Java

The obvious answer to this is "that's what the JLS says."

Thinking about why that is, consider that this behavior can be useful in certain cases. Let's say you want to check a string against a set of other strings, but the number of other strings can vary.

So you have something like this:

for(String s : myStrings) {

where some s's are empty strings.

If the empty string is interpreted as "no input," and if your purpose here is ensure that aString contains all the "inputs" in myStrings, then it is misleading for the empty string to return false. All strings contain it because it is nothing. To say they didn't contain it would imply that the empty string had some substance that was not captured in the string, which is false.

How to make HTML element resizable using pure Javascript?

var resizeHandle = document.getElementById('resizable');_x000D_
var box = document.getElementById('resize');_x000D_
resizeHandle.addEventListener('mousedown', initialiseResize, false);_x000D_
function initialiseResize(e) {_x000D_
  window.addEventListener('mousemove', startResizing, false);_x000D_
  window.addEventListener('mouseup', stopResizing, false);_x000D_
function stopResizing(e) {_x000D_
  window.removeEventListener('mousemove', startResizing, false);_x000D_
  window.removeEventListener('mouseup', stopResizing, false);_x000D_
function startResizing(e) {_x000D_ = (e.clientX) + 'px';_x000D_ = (e.clientY) + 'px';_x000D_
function startResizing(e) {_x000D_ = (e.clientX - box.offsetLeft) + 'px';_x000D_ = (e.clientY - box.offsetTop) + 'px';_x000D_
#resize {_x000D_
  position: relative;_x000D_
  width: 130px;_x000D_
  height: 130px;_x000D_
  border: 2px solid blue;_x000D_
  color: white;_x000D_
#resizable {_x000D_
  background-color: white;_x000D_
  width: 10px;_x000D_
  height: 10px;_x000D_
  cursor: se-resize;_x000D_
  position: absolute;_x000D_
  right: 0;_x000D_
  bottom: 0;_x000D_
<div id="resize">_x000D_
  <div id="resizable">_x000D_

'list' object has no attribute 'shape'

If you have list, you can print its shape as if it is converted to array

import numpy as np

How to undo the last commit in git

I think you haven't messed up yet. Try:

git reset HEAD^

This will bring the dir to state before you've made the commit, HEAD^ means the parent of the current commit (the one you don't want anymore), while keeping changes from it (unstaged).

Change link color of the current page with CSS

@Presto Thanks! Yours worked perfectly for me, but I came up with a simpler version to save changing everything around.

Add a <span> tag around the desired link text, specifying class within. (e.g. home tag)

<nav id="top-menu">
        <li> <a href="home.html"><span class="currentLink">Home</span></a> </li>
        <li> <a href="about.html">About</a> </li>
        <li> <a href="cv.html">CV</a> </li>
        <li> <a href="photos.html">Photos</a> </li>
        <li> <a href="archive.html">Archive</a> </li>
        <li> <a href="contact.html">Contact</a></li>

Then edit your CSS accordingly:

.currentLink {

DataTables: Uncaught TypeError: Cannot read property 'defaults' of undefined

The problem is that dataTable is not defined at the point you are calling this method.

Ensure that you are loading the .js files in the correct order:

<script src="/Scripts/jquery.dataTables.js"></script>
<script src="/Scripts/dataTables.bootstrap.js"></script>

Configuring ObjectMapper in Spring

I am using Spring 3.2.4 and Jackson FasterXML 2.1.1.

I have created a custom JacksonObjectMapper that works with explicit annotations for each attribute of the Objects mapped:

package com.test;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

public class MyJaxbJacksonObjectMapper extends ObjectMapper {

public MyJaxbJacksonObjectMapper() {

    this.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY)
            .setVisibility(PropertyAccessor.CREATOR, JsonAutoDetect.Visibility.ANY)
            .setVisibility(PropertyAccessor.SETTER, JsonAutoDetect.Visibility.NONE)
            .setVisibility(PropertyAccessor.GETTER, JsonAutoDetect.Visibility.NONE)
            .setVisibility(PropertyAccessor.IS_GETTER, JsonAutoDetect.Visibility.NONE);

    this.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);

Then this is instantiated in the context-configuration (servlet-context.xml):


        <beans:bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
            <beans:property name="objectMapper">
                <beans:bean class="com.test.MyJaxbJacksonObjectMapper" />


This works fine!

R object identification

I usually start out with some combination of:

sapply(obj, class)
sapply(obj, attributes)

as appropriate based on what's revealed. For example, try with:

obj <- data.frame(a=1:26, b=letters)
obj <- list(a=1:26, b=letters, c=list(d=1:26, e=letters))
obj <- lm(dist ~ speed, data=cars)


If obj is an S3 or S4 object, you can also try methods or showMethods, showClass, etc. Patrick Burns' R Inferno has a pretty good section on this (sec #7).

EDIT: Dirk and Hadley mention str(obj) in their answers. It really is much better than any of the above for a quick and even detailed peek into an object.

Content is not allowed in Prolog SAXParserException

I faced the same issue. Our application running on four application servers and due to invalid schema location mentioned on one of the web service WSDL, hung threads are generated on the servers . The appliucations got down frequently. After corrected the schema Location , the issue got resolved.

How to determine if a number is positive or negative?

if (((Double)calcYourDouble()).toString().contains("-"))
else doThat();

Why do I get a "permission denied" error while installing a gem?

I think the problem happened when you use rbenv. Try the below commands to fix it.

rbenv shell {rb_version}
rbenv global {rb_version}
rbenv local {rb_version}

How to disable javax.swing.JButton in java?

For that I have written the following code in the "ActionPeformed(...)" method of the "Start" button

You need that code to be in the actionPerformed(...) of the ActionListener registered with the Start button, not for the Start button itself.

You can add a simple ActionListener like this:

JButton startButton = new JButton("Start");
startButton.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ae) {

note that your startButton above will need to be final in the above example if you want to create the anonymous listener in local scope.

Gradle failed to resolve library in Android Studio

i had the same problem, i added the following lines in build.gradle

allprojects {
    repositories {
        maven { url "" }

        maven {
            url ''

How to play a sound in C#, .NET

Additional Information.

This is a bit high-level answer for applications which want to seamlessly fit into the Windows environment. Technical details of playing particular sound were provided in other answers. Besides that, always note these two points:

  1. Use five standard system sounds in typical scenarios, i.e.

    • Asterisk - play when you want to highlight current event

    • Question - play with questions (system message box window plays this one)

    • Exclamation - play with excalamation icon (system message box window plays this one)

    • Beep (default system sound)

    • Critical stop ("Hand") - play with error (system message box window plays this one)

    Methods of class System.Media.SystemSounds will play them for you.

  2. Implement any other sounds as customizable by your users in Sound control panel

    • This way users can easily change or remove sounds from your application and you do not need to write any user interface for this – it is already there
    • Each user profile can override these sounds in own way
    • How-to:

What is the relative performance difference of if/else versus switch statement in Java?

For most switch and most if-then-else blocks, I can't imagine that there are any appreciable or significant performance related concerns.

But here's the thing: if you're using a switch block, its very use suggests that you're switching on a value taken from a set of constants known at compile time. In this case, you really shouldn't be using switch statements at all if you can use an enum with constant-specific methods.

Compared to a switch statement, an enum provides better type safety and code that is easier to maintain. Enums can be designed so that if a constant is added to the set of constants, your code won't compile without providing a constant-specific method for the new value. On the other hand, forgetting to add a new case to a switch block can sometimes only be caught at run time if you're lucky enough to have set your block up to throw an exception.

Performance between switch and an enum constant-specific method should not be significantly different, but the latter is more readable, safer, and easier to maintain.

How to change an Eclipse default project into a Java project

Another possible way is to delete the project from Eclipse (but don't delete the project contents from disk!) and then use the New Java Project wizard to create a project in-place. That wizard will detect the Java code and set up build paths automatically.

RegEx pattern any two letters followed by six numbers

Everything you need here can be found in this quickstart guide. A straightforward solution would be [A-Za-z][A-Za-z]\d\d\d\d\d\d or [A-Za-z]{2}\d{6}.

If you want to accept only capital letters then replace [A-Za-z] with [A-Z].

correct configuration for nginx to localhost?

Fundamentally you hadn't declare location which is what nginx uses to bind URL with resources.

 server {
            listen       80;
            server_name  localhost;

            access_log  logs/localhost.access.log  main;

            location / {
                root /var/www/board/public;
                index index.html index.htm index.php;

Format price in the current locale and currency

$formattedPrice = Mage::helper('core')->currency($_finalPrice,true,false);

What does `unsigned` in MySQL mean and when to use it?

MySQL says:

All integer types can have an optional (nonstandard) attribute UNSIGNED. Unsigned type can be used to permit only nonnegative numbers in a column or when you need a larger upper numeric range for the column. For example, if an INT column is UNSIGNED, the size of the column's range is the same but its endpoints shift from -2147483648 and 2147483647 up to 0 and 4294967295.

When do I use it ?

Ask yourself this question: Will this field ever contain a negative value?
If the answer is no, then you want an UNSIGNED data type.

A common mistake is to use a primary key that is an auto-increment INT starting at zero, yet the type is SIGNED, in that case you’ll never touch any of the negative numbers and you are reducing the range of possible id's to half.