Programs & Examples On #Function templates

A function template behaves like a regular function except that works with types specified on the template arguments. The template arguments could be part of the function arguments and/or the function body. Each unique combination of template arguments will become an unique function when instantiated.

Can a class member function template be virtual?

In the other answers the proposed template function is a facade and doesn't offer any practical benefit.

  • Template functions are useful for writing code only once using different types.
  • Virtual functions are useful for having a common interface for different classes.

The language doesn't allow virtual template functions but with a workaround it is possible to have both, e.g. one template implementation for each class and a virtual common interface.

It is however necessary to define for each template type combination a dummy virtual wrapper function:

#include <memory>
#include <iostream>
#include <iomanip>

// Abstract class with virtual functions
class Geometry {
    virtual void getArea(float &area) = 0;
    virtual void getArea(long double &area) = 0;

// Square
class Square : public Geometry {
    float size {1};

    // virtual wrapper functions call template function for square
    virtual void getArea(float &area) { getAreaT(area); }
    virtual void getArea(long double &area) { getAreaT(area); }

    // Template function for squares
    template <typename T>
    void getAreaT(T &area) {
        area = static_cast<T>(size * size);

// Circle
class Circle : public Geometry  {
    float radius {1};

    // virtual wrapper functions call template function for circle
    virtual void getArea(float &area) { getAreaT(area); }
    virtual void getArea(long double &area) { getAreaT(area); }

    // Template function for Circles
    template <typename T>
    void getAreaT(T &area) {
        area = static_cast<T>(radius * radius * 3.1415926535897932385L);

// Main
int main()
    // get area of square using template based function T=float
    std::unique_ptr<Geometry> geometry = std::make_unique<Square>();
    float areaSquare;

    // get area of circle using template based function T=long double
    geometry = std::make_unique<Circle>();
    long double areaCircle;

    std::cout << std::setprecision(20) << "Square area is " << areaSquare << ", Circle area is " << areaCircle << std::endl;
    return 0;


Square area is 1, Circle area is 3.1415926535897932385

Try it here

Copy-item Files in Folders and subfolders in the same directory structure of source server using PowerShell

one time i found this script, this copy folder and files and keep the same structure of the source in the destination, you can make some tries with this.

# Find the source files

# Set the target file
Get-ChildItem $sourceDir -Include *.* -Recurse |  foreach {

    # Remove the original  root folder
    $split = $_.Fullname  -split '\\'
    $DestFile =  $split[1..($split.Length - 1)] -join '\' 

    # Build the new  destination file path
    $DestFile = $targetDir+$DestFile

    # Move-Item won't  create the folder structure so we have to 
    # create a blank file  and then overwrite it
    $null = New-Item -Path  $DestFile -Type File -Force
    Move-Item -Path  $_.FullName -Destination $DestFile -Force

Blur effect on a div element

Try using this library:

That should do it for ya.

Travel/Hotel API's?

Try and their API there. They have a very different data that big players, really good coverage mostly in Europe and good API conditions.

Jasmine JavaScript Testing - toBe vs toEqual

toBe() versus toEqual(): toEqual() checks equivalence. toBe(), on the other hand, makes sure that they're the exact same object.

I would say use toBe() when comparing values, and toEqual() when comparing objects.

When comparing primitive types, toEqual() and toBe() will yield the same result. When comparing objects, toBe() is a stricter comparison, and if it is not the exact same object in memory this will return false. So unless you want to make sure it's the exact same object in memory, use toEqual() for comparing objects.

Check this link out for more info :

Now when looking at the difference between toBe() and toEqual() when it comes to numbers, there shouldn't be any difference so long as your comparison is correct. 5 will always be equivalent to 5.

A nice place to play around with this to see different outcomes is here


An easy way to look at toBe() and toEqual() is to understand what exactly they do in JavaScript. According to Jasmine API, found here:

toEqual() works for simple literals and variables, and should work for objects

toBe() compares with ===

Essentially what that is saying is toEqual() and toBe() are similar Javascripts === operator except toBe() is also checking to make sure it is the exact same object, in that for the example below objectOne === objectTwo //returns false as well. However, toEqual() will return true in that situation.

Now, you can at least understand why when given:

var objectOne = {
    propertyOne: str,
    propertyTwo: num    

var objectTwo = {
    propertyOne: str,
    propertyTwo: num    

expect(objectOne).toBe(objectTwo); //returns false

That is because, as stated in this answer to a different, but similar question, the === operator actually means that both operands reference the same object, or in case of value types, have the same value.

Conditional Logic on Pandas DataFrame

In [34]: import pandas as pd

In [35]: import numpy as np

In [36]:  df = pd.DataFrame([1,2,3,4], columns=["data"])

In [37]: df
0     1
1     2
2     3
3     4

In [38]: df["desired_output"] = np.where(df["data"] <2.5, "False", "True")

In [39]: df
   data desired_output
0     1          False
1     2          False
2     3           True
3     4           True

How to get the Facebook user id using the access token

You can use below code on onSuccess(LoginResult loginResult)


How to get index in Handlebars each helper?

I know this is too late. But i solved this issue with following Code:

Java Script:

Handlebars.registerHelper('eachData', function(context, options) {
      var fn = options.fn, inverse = options.inverse, ctx;
      var ret = "";

      if(context && context.length > 0) {
        for(var i=0, j=context.length; i<j; i++) {
          ctx = Object.create(context[i]);
          ctx.index = i;
          ret = ret + fn(ctx);
      } else {
        ret = inverse(this);
      return ret;


{{#eachData items}}
 {{index}} // You got here start with 0 index

if you want start your index with 1 you should do following code:


Handlebars.registerHelper('eachData', function(context, options) {
      var fn = options.fn, inverse = options.inverse, ctx;
      var ret = "";

      if(context && context.length > 0) {
        for(var i=0, j=context.length; i<j; i++) {
          ctx = Object.create(context[i]);
          ctx.index = i;
          ret = ret + fn(ctx);
      } else {
        ret = inverse(this);
      return ret;

Handlebars.registerHelper("math", function(lvalue, operator, rvalue, options) {
    lvalue = parseFloat(lvalue);
    rvalue = parseFloat(rvalue);

    return {
        "+": lvalue + rvalue


{{#eachData items}}
     {{math index "+" 1}} // You got here start with 1 index


Setting up SSL on a local xampp/apache server

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

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

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

#LoadModule ssl_module modules/

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

PHP part - enabling adldap to use ldap over ssl

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

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

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


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

see also:

How can I check if mysql is installed on ubuntu?

"mysql" may be found even if mysql and mariadb is uninstalled, but not "mysqld".

Faster than rpm -qa | grep mysqld is:

which mysqld

Pad a number with leading zeros in JavaScript

You could do something like this:

function pad ( num, size ) {
  return ( Math.pow( 10, size ) + ~~num ).toString().substring( 1 );

Edit: This was just a basic idea for a function, but to add support for larger numbers (as well as invalid input), this would probably be better:

function pad ( num, size ) {
  if (num.toString().length >= size) return num;
  return ( Math.pow( 10, size ) + Math.floor(num) ).toString().substring( 1 );

This does 2 things:

  1. If the number is larger than the specified size, it will simply return the number.
  2. Using Math.floor(num) in place of ~~num will support larger numbers.

How can I capture the result of var_dump to a string?

From the PHP manual:

This function displays structured information about one or more expressions that includes its type and value.

So, here is the real return version of PHP's var_dump(), which actually accepts a variable-length argument list:

function var_dump_str()
    $argc = func_num_args();
    $argv = func_get_args();

    if ($argc > 0) {
        call_user_func_array('var_dump', $argv);
        $result = ob_get_contents();
        return $result;

    return '';

WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for jquery

Right click on your website go to property pages and check both the check-boxes under Accessibility validation click on ok. run the website.

Use different Python version with virtualenv

On windows:

py -3.4x32 -m venv venv34


py -2.6.2 -m venv venv26

This uses the py launcher which will find the right python executable for you (assuming you have it installed).

How to check in Javascript if one element is contained within another

Take a look at Node#compareDocumentPosition.

function isDescendant(ancestor,descendant){
    return ancestor.compareDocumentPosition(descendant) & 

function isAncestor(descendant,ancestor){
    return descendant.compareDocumentPosition(ancestor) & 


Not supported in IE<=8.

Rename all files in directory from $filename_h to $filename_half?

Are you looking for a pure bash solution? There are many approaches, but here's one.

for file in *_h.png ; do mv "$file" "${file%%_h.png}_half.png" ; done

This presumes that the only files in the current directory that end in _h.png are the ones you want to rename.

Much more specifically

for file in 0{5..6}_h.png ; do mv "$file" "${file/_h./_half.}" ; done

Presuming those two examples are your only. files.

For the general case, file renaming in has been covered before.

How to change the output color of echo in Linux

You can use these ANSI escape codes:

Black        0;30     Dark Gray     1;30
Red          0;31     Light Red     1;31
Green        0;32     Light Green   1;32
Brown/Orange 0;33     Yellow        1;33
Blue         0;34     Light Blue    1;34
Purple       0;35     Light Purple  1;35
Cyan         0;36     Light Cyan    1;36
Light Gray   0;37     White         1;37

And then use them like this in your script:

#    .---------- constant part!
#    vvvv vvvv-- the code from above
NC='\033[0m' # No Color
printf "I ${RED}love${NC} Stack Overflow\n"

which prints love in red.

From @james-lim's comment, if you are using the echo command, be sure to use the -e flag to allow backslash escapes.

# Continued from above example
echo -e "I ${RED}love${NC} Stack Overflow"

(don't add "\n" when using echo unless you want to add an additional empty line)

Is there a performance difference between CTE , Sub-Query, Temporary Table or Table Variable?

SQL is a declarative language, not a procedural language. That is, you construct a SQL statement to describe the results that you want. You are not telling the SQL engine how to do the work.

As a general rule, it is a good idea to let the SQL engine and SQL optimizer find the best query plan. There are many person-years of effort that go into developing a SQL engine, so let the engineers do what they know how to do.

Of course, there are situations where the query plan is not optimal. Then you want to use query hints, restructure the query, update statistics, use temporary tables, add indexes, and so on to get better performance.

As for your question. The performance of CTEs and subqueries should, in theory, be the same since both provide the same information to the query optimizer. One difference is that a CTE used more than once could be easily identified and calculated once. The results could then be stored and read multiple times. Unfortunately, SQL Server does not seem to take advantage of this basic optimization method (you might call this common subquery elimination).

Temporary tables are a different matter, because you are providing more guidance on how the query should be run. One major difference is that the optimizer can use statistics from the temporary table to establish its query plan. This can result in performance gains. Also, if you have a complicated CTE (subquery) that is used more than once, then storing it in a temporary table will often give a performance boost. The query is executed only once.

The answer to your question is that you need to play around to get the performance you expect, particularly for complex queries that are run on a regular basis. In an ideal world, the query optimizer would find the perfect execution path. Although it often does, you may be able to find a way to get better performance.

Finding sum of elements in Swift array

This also works:

let arr = [1,2,3,4,5,6,7,8,9,10]
var sumedArr = arr.reduce(0, combine: {$0 + $1})

The result will be: 55

Email and phone Number Validation in android

in Kotlin you can use Extension function to validate input

// for Email validation

 fun String.isValidEmail(): Boolean =
        this.isNotEmpty() && Patterns.EMAIL_ADDRESS.matcher(this).matches()

// for Phone validation

fun String.isValidMobile(phone: String): Boolean {
    return Patterns.PHONE.matcher(phone).matches()

iOS 7.0 No code signing identities found

you need not to delete all your profiles.I had same issue and fixed it by installing the missing certificates. You might forgot to install the required certificate for the provisioning profile you are using for code signing.

  • make sure that you installed desired certificates(development/distribution) into keychain for the code-signing provision profile(development/distribution).

Where do I call the BatchNormalization function in Keras?

Just to answer this question in a little more detail, and as Pavel said, Batch Normalization is just another layer, so you can use it as such to create your desired network architecture.

The general use case is to use BN between the linear and non-linear layers in your network, because it normalizes the input to your activation function, so that you're centered in the linear section of the activation function (such as Sigmoid). There's a small discussion of it here

In your case above, this might look like:

# import BatchNormalization
from keras.layers.normalization import BatchNormalization

# instantiate model
model = Sequential()

# we can think of this chunk as the input layer
model.add(Dense(64, input_dim=14, init='uniform'))

# we can think of this chunk as the hidden layer    
model.add(Dense(64, init='uniform'))

# we can think of this chunk as the output layer
model.add(Dense(2, init='uniform'))

# setting up the optimization of our weights 
sgd = SGD(lr=0.1, decay=1e-6, momentum=0.9, nesterov=True)
model.compile(loss='binary_crossentropy', optimizer=sgd)

# running the fitting, y_train, nb_epoch=20, batch_size=16, show_accuracy=True, validation_split=0.2, verbose = 2)

Hope this clarifies things a bit more.

What is the JUnit XML format specification that Hudson supports?

I just grabbed the junit-4.xsd that others have linked to and used a tool named XMLSpear to convert the schema to a blank XML file with the options shown below. This is the (slightly cleaned up) result:

<?xml version="1.0" encoding="UTF-8"?>
<testsuites disabled="" errors="" failures="" name="" tests="" time="">
    <testsuite disabled="" errors="" failures="" hostname="" id=""
               name="" package="" skipped="" tests="" time="" timestamp="">
            <property name="" value=""/>
        <testcase assertions="" classname="" name="" status="" time="">
            <error message="" type=""/>
            <failure message="" type=""/>

Some of these items can occur multiple times:

  • There can only be one testsuites element, since that’s how XML works, but there can be multiple testsuite elements within the testsuites element.
  • Each properties element can have multiple property children.
  • Each testsuite element can have multiple testcase children.
  • Each testcase element can have multiple error, failure, system-out, or system-err children.

XMLSpear options

Changing default shell in Linux

You can change the passwd file directly for the particular user or use the below command

chsh -s /usr/local/bin/bash username

Then log out and log in

Python: How to use RegEx in an if statement?

First you compile the regex, then you have to use it with match, find, or some other method to actually run it against some input.

import os
import re
import shutil

def test():
    files = os.listdir(".")
    pattern = re.compile(regex_txt, re.IGNORECASE)
    for x in (files):
        with open((x), 'r') as input_file:
            for line in input_file:
                    shutil.copy(x, "C:/Users/David/Desktop/Test/MyFiles2")

How can I dynamically set the position of view in Android?

Set the left position of this view relative to its parent:

view.setLeft(int leftPosition);

Set the right position of this view relative to its parent:

view.setRight(int rightPosition);

Set the top position of this view relative to its parent:

view.setTop(int topPosition);

Set the bottom position of this view relative to its parent:

view.setBottom(int bottomPositon);

The above methods are used to set the position the view related to its parent.

What is the difference between os.path.basename() and os.path.dirname()?

To summarize what was mentioned by Breno above

Say you have a variable with a path to a file

path = '/home/User/Desktop/'

os.path.basename(path) returns the string ''


os.path.dirname(path) returns the string '/home/User/Desktop' (without a trailing slash '/')

These functions are used when you have to get the filename/directory name given a full path name.

In case the file path is just the file name (e.g. instead of path = '/home/User/Desktop/' you just have, os.path.dirname(path) returns an empty string.

How to return JSon object

First of all, there's no such thing as a JSON object. What you've got in your question is a JavaScript object literal (see here for a great discussion on the difference). Here's how you would go about serializing what you've got to JSON though:

I would use an anonymous type filled with your results type:

string json = JsonConvert.SerializeObject(new
    results = new List<Result>()
        new Result { id = 1, value = "ABC", info = "ABC" },
        new Result { id = 2, value = "JKL", info = "JKL" }

Also, note that the generated JSON has result items with ids of type Number instead of strings. I doubt this will be a problem, but it would be easy enough to change the type of id to string in the C#.

I'd also tweak your results type and get rid of the backing fields:

public class Result
    public int id { get ;set; }
    public string value { get; set; }
    public string info { get; set; }

Furthermore, classes conventionally are PascalCased and not camelCased.

Here's the generated JSON from the code above:

  "results": [
      "id": 1,
      "value": "ABC",
      "info": "ABC"
      "id": 2,
      "value": "JKL",
      "info": "JKL"

Javascript to Select Multiple options

A pure javascript solution

<select id="choice" multiple="multiple">
  <option value="1">One</option>
  <option value="2">two</option>
  <option value="3">three</option>
<script type="text/javascript">

var optionsToSelect = ['One', 'three'];
var select = document.getElementById( 'choice' );

for ( var i = 0, l = select.options.length, o; i < l; i++ )
  o = select.options[i];
  if ( optionsToSelect.indexOf( o.text ) != -1 )
    o.selected = true;


Although I agree this should be done server-side.

How to return JSON with ASP.NET & jQuery

Just return object: it will be parser to JSON.

public Object Get(string id)
    return new { id = 1234 };

Finding row index containing maximum value using R

See ?which.max

> which.max( matrix[,2] )
[1] 2

How do I sort strings alphabetically while accounting for value when a string is numeric?

Expanding on Jeff Paulsen answer. I wanted to make sure it didn't matter how many number or char groups were in the strings:

public class SemiNumericComparer : IComparer<string>
    public int Compare(string s1, string s2)
        if (int.TryParse(s1, out var i1) && int.TryParse(s2, out var i2))
            if (i1 > i2)
                return 1;

            if (i1 < i2)
                return -1;

            if (i1 == i2)
                return 0;

        var text1 = SplitCharsAndNums(s1);
        var text2 = SplitCharsAndNums(s2);

        if (text1.Length > 1 && text2.Length > 1)

            for (var i = 0; i < Math.Max(text1.Length, text2.Length); i++)

                if (text1[i] != null && text2[i] != null)
                    var pos = Compare(text1[i], text2[i]);
                    if (pos != 0)
                        return pos;
                    //text1[i] is null there for the string is shorter and comes before a longer string.
                    if (text1[i] == null)
                        return -1;
                    if (text2[i] == null)
                        return 1;

        return string.Compare(s1, s2, true);

    private string[] SplitCharsAndNums(string text)
        var sb = new StringBuilder();
        for (var i = 0; i < text.Length - 1; i++)
            if ((!char.IsDigit(text[i]) && char.IsDigit(text[i + 1])) ||
                (char.IsDigit(text[i]) && !char.IsDigit(text[i + 1])))
                sb.Append(" ");

        sb.Append(text[text.Length - 1]);

        return sb.ToString().Split(' ');

I also took SplitCharsAndNums from an SO Page after amending it to deal with file names.

Remove all spaces from a string in SQL Server

Check and Try the below script (Unit Tested)-


--Test Samples
INSERT INTO @Tbl (col_1)
('  EY     y            
, ('  EY     P    ort       Chennai   ')
, ('  EY     Old           Park   ')
, ('  EY   ')
, ('  EY   ')

        REPLACE(col_1,CHAR(10),' ')
        ,CHAR(11),' ')
        ,CHAR(12),' ')
        ,CHAR(13),' ')
        ,CHAR(14),' ')
        ,CHAR(160),' ')
        ,CHAR(13)+CHAR(10),' ')
    ,CHAR(9),' ')
    ,' ',CHAR(17)+CHAR(18))
    ,CHAR(17)+CHAR(18),' ')
    )) AS [OUTPUT]
FROM @Tbl;

What is the difference between ng-if and ng-show/ng-hide

Fact, that ng-if directive, unlike ng-show, creates its own scope, leads to interesting practical difference:

angular.module('app', []).controller('ctrl', function($scope){_x000D_
  $scope.delete = function(array, item){_x000D_
    array.splice(array.indexOf(item), 1);_x000D_
<script src=""></script>_x000D_
<div ng-app='app' ng-controller='ctrl'>_x000D_
   <ul ng-init='arr1 = [1,2,3]'>_x000D_
      <li ng-repeat='x in arr1'>_x000D_
        <button ng-if='!show' ng-click='show=!show'>Delete {{show}}</button>_x000D_
        <button ng-if='show' ng-click='delete(arr1, x)'>Yes {{show}}</button>_x000D_
        <button ng-if='show' ng-click='show=!show'>No</button>_x000D_
   <ul ng-init='arr2 = [1,2,3]'>_x000D_
      <li ng-repeat='x in arr2'>_x000D_
        <button ng-show='!show' ng-click='show=!show'>Delete {{show}}</button>_x000D_
        <button ng-show='show' ng-click='delete(arr2, x)'>Yes {{show}}</button>_x000D_
        <button ng-show='show' ng-click='show=!show'>No</button>_x000D_
   <h4>ng-if with $parent:</h4>_x000D_
    <ul ng-init='arr3 = [1,2,3]'>_x000D_
      <li ng-repeat='item in arr3'>_x000D_
        <button ng-if='!show' ng-click='$!$'>Delete {{$}}</button>_x000D_
        <button ng-if='show' ng-click='delete(arr3, x)'>Yes {{$}}</button>_x000D_
        <button ng-if='show' ng-click='$!$'>No</button>_x000D_

At first list, on-click event, show variable, from innner/own scope, is changed, but ng-if is watching on another variable from outer scope with same name, so solution not works. At case of ng-show we have the only one show variable, that is why it works. To fix first attempt, we should reference to show from parent/outer scope via $

SQL - Create view from multiple tables

Union is not what you want. You want to use joins to create single rows. It's a little unclear what constitutes a unique row in your tables and how they really relate to each other and it's also unclear if one table will have rows for every country in every year. But I think this will work:


  SELECT,i.year,p.pop,,i.income FROM
    INCOME i
    POP p 
    Food f

The left (outer) join will return rows from the first table even if there are no matches in the second. I've written this assuming you would have a row for every country for every year in the income table. If you don't things get a bit hairy as MySQL does not have built in support for FULL OUTER JOINs last I checked. There are ways to simulate it, and they would involve unions. This article goes into some depth on the subject:

How to get client IP address using jQuery

A simple AJAX call to your server, and then the serverside logic to get the ip address should do the trick.

$.getJSON('getip.php', function(data){
  alert('Your ip is: ' +  data.ip);

Then in php you might do:

/* getip.php */
header('Cache-Control: no-cache, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
header('Content-type: application/json');

if (!empty($_SERVER['HTTP_CLIENT_IP']))
elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))
print json_encode(array('ip' => $ip));

MySQL Query - Records between Today and Last 30 Days

You need to apply DATE_FORMAT in the SELECT clause, not the WHERE clause:

SELECT  DATE_FORMAT(create_date, '%m/%d/%Y')
FROM    mytable

Also note that CURDATE() returns only the DATE portion of the date, so if you store create_date as a DATETIME with the time portion filled, this query will not select the today's records.

In this case, you'll need to use NOW instead:

SELECT  DATE_FORMAT(create_date, '%m/%d/%Y')
FROM    mytable

How to obtain Telegram chat_id for a specific user?

The message updates you receive via getUpdates or your webhook will contain the chat ID for the specific message. It will be contained under the key.

This seems like the only way you are able to retrieve the chat ID. So if you want to write something where the bot initiates the conversation you will probably have to store the chat ID in relation to the user in some sort of key->value store like MemCache or Redis.

I believe their documentation suggests something similar here, You can use deep-linking to initiate a conversation without requiring the user to type a message first.

SMTP error 554

To resolve problem go to the MDaemon-->setup-->Miscellaneous options-->Server-->SMTP Server Checks commands and headers for RFC Compliance

How to invoke a Linux shell command from Java

exec does not execute a command in your shell


Process p = Runtime.getRuntime().exec(new String[]{"csh","-c","cat /home/narek/pk.txt"});


EDIT:: I don't have csh on my system so I used bash instead. The following worked for me

Process p = Runtime.getRuntime().exec(new String[]{"bash","-c","ls /home/XXX"});

Extract specific columns from delimited file using Awk

Not using awk but the simplest way I was able to get this done was to just use csvtool. I had other use cases as well to use csvtool and it can handle the quotes or delimiters appropriately if they appear within the column data itself.

csvtool format '%(2)\n' input.csv
csvtool format '%(2),%(3),%(4)\n' input.csv

Replacing 2 with the column number will effectively extract the column data you are looking for.

How to declare a constant in Java

  1. You can use an enum type in Java 5 and onwards for the purpose you have described. It is type safe.
  2. A is an instance variable. (If it has the static modifier, then it becomes a static variable.) Constants just means the value doesn't change.
  3. Instance variables are data members belonging to the object and not the class. Instance variable = Instance field.

If you are talking about the difference between instance variable and class variable, instance variable exist per object created. While class variable has only one copy per class loader regardless of the number of objects created.

Java 5 and up enum type

public enum Color{
 RED("Red"), GREEN("Green");

 private Color(String color){
    this.color = color;

  private String color;

  public String getColor(){
    return this.color;

  public String toString(){
    return this.color;

If you wish to change the value of the enum you have created, provide a mutator method.

public enum Color{
 RED("Red"), GREEN("Green");

 private Color(String color){
    this.color = color;

  private String color;

  public String getColor(){
    return this.color;

  public void setColor(String color){
    this.color = color;

  public String toString(){
    return this.color;

Example of accessing:

public static void main(String args[]){

  // or


jQuery - Call ajax every 10 seconds

          //do something with response data
}, 10000);//time in milliseconds 

What is sr-only in Bootstrap 3?

As JoshC said, the class .sr-only is used to visually hide the information used for screen readers only. But not only to hide labels. You might consider hiding various other elements such as "skip to main content" link, icons which have an alternative texts etc.

BTW. you can also use .sr-only sr-only-focusable if you need the element to become visible when focused e.g. "skip to main content"

If you want make your website even more accessible I recommend to start here:


According to the World Health Organization, 285 million people have vision impairments. So making a website accessible is important.

IMPORTANT: Avoid treating disabled users differently. Generally speaking try to avoid developing a different content for different groups of users. Instead try to make accessible the existing content so that it simply works out-of-the-box and for all not specifically targeting e.g. screen readers. In other words don't try to reinvent the wheel. Otherwise the resulting accessibility will often be worse than if there was nothing developed at all. We developers should not assume how those users will use our website. So be very careful when you need to develop such solutions. Obviously a "skip link" is a good example of such content if it's made visible when focused. But there many bad examples too. Such would be hiding from a screen reader a "zoom" button on the map assuming that it has no relevance to blind users. But surprisingly, a zoom function indeed is used among blind users! They like to download images like many other users do (even in high resolution), for sending them to somebody else or for using them in some other context. Source - Read more @ADG: Bad ARIA practices

Get the Query Executed in Laravel 3/4

You can enable the "Profiler" in Laravel 3 by setting

'profiler' => true,

In your application/config/application.php and application/config/database.php

This enables a bar at the bottom of each page. One of its features is listing the executed queries and how long each one took.

enter image description here

Multiple parameters in a List. How to create without a class?

To add to what other suggested I like the following construct to avoid the annoyance of adding members to keyvaluepair collections.

public class KeyValuePairList<Tkey,TValue> : List<KeyValuePair<Tkey,TValue>>{
    public void Add(Tkey key, TValue value){
        base.Add(new KeyValuePair<Tkey, TValue>(key, value));

What this means is that the constructor can be initialized with better syntax::

var myList = new KeyValuePairList<int,string>{{1,"one"},{2,"two"},{3,"three"}};

I personally like the above code over the more verbose examples Unfortunately C# does not really support tuple types natively so this little hack works wonders.

If you find yourself really needing more than 2, I suggest creating abstractions against the tuple type.(although Tuple is a class not a struct like KeyValuePair this is an interesting distinction).

Curiously enough, the initializer list syntax is available on any IEnumerable and it allows you to use any Add method, even those not actually enumerable by your object. It's pretty handy to allow things like adding an object[] member as a params object[] member.

How to resolve 'unrecognized selector sent to instance'?

1) Is the synthesize within @implementation block?

2) Should you refer to self.classA = [[ClassA alloc] init]; and self.classA.downloadUrl = @"..." instead of plain classA?

3) In your myApp.m file you need to import ClassA.h, when it's missing it will default to a number, or pointer? (in C variables default to int if not found by compiler):

#import "ClassA.h".

Client to send SOAP request and receive response

So this is my final code after googling for 2 days on how to add a namespace and make soap request along with the SOAP envelope without adding proxy/Service Reference

class Request
    public static void Execute(string XML)
            HttpWebRequest request = CreateWebRequest();
            XmlDocument soapEnvelopeXml = new XmlDocument();

            using (Stream stream = request.GetRequestStream())

            using (WebResponse response = request.GetResponse())
                using (StreamReader rd = new StreamReader(response.GetResponseStream()))
                    string soapResult = rd.ReadToEnd();
        catch (Exception ex)

    private static HttpWebRequest CreateWebRequest()
        string ICMURL = System.Configuration.ConfigurationManager.AppSettings.Get("ICMUrl");
        HttpWebRequest webRequest = null;

            webRequest = (HttpWebRequest)WebRequest.Create(ICMURL);
            webRequest.ContentType = "text/xml;charset=\"utf-8\"";
            webRequest.Accept = "text/xml";
            webRequest.Method = "POST";
        catch (Exception ex)
        return webRequest;

    private static string AddNamespace(string XML)
        string result = string.Empty;

            XmlDocument xdoc = new XmlDocument();

            XmlElement temproot = xdoc.CreateElement("ws", "Request", "");
            temproot.InnerXml = xdoc.DocumentElement.InnerXml;
            result = temproot.OuterXml;

        catch (Exception ex)

        return result;

    private static string AppendEnvelope(string data)
        string head= @"<soapenv:Envelope xmlns:soapenv="""" ><soapenv:Header/><soapenv:Body>";
        string end = @"</soapenv:Body></soapenv:Envelope>";
        return head + data + end;

submit the form using ajax

I would suggest to use jquery for this type of requirement . Give this a try

<div id="commentList"></div>
<div id="addCommentContainer">
    <p>Add a Comment</p> <br/> <br/>
    <form id="addCommentForm" method="post" action="">
            Your Name <br/>
            <input type="text" name="name" id="name" />

            <br/> <br/>
            Comment Body <br/>
            <textarea name="body" id="body" cols="20" rows="5"></textarea>

            <input type="submit" id="submit" value="Submit" />

    /* The following code is executed once the DOM is loaded */

    /* This flag will prevent multiple comment submits: */
    var working = false;
         type: 'POST',
         url: "mysubmitpage.php",
         data: $('#addCommentForm').serialize(), 
         success: function(response) {
            alert("Submitted comment"); 
             $("#commentList").append("Name:" + $("#name").val() + "<br/>comment:" + $("#body").val());
        error: function() {
             //$("#commentList").append($("#name").val() + "<br/>" + $("#body").val());
            alert("There was an error submitting comment");

error: ‘NULL’ was not declared in this scope

GCC is taking steps towards C++11, which is probably why you now need to include cstddef in order to use the NULL constant. The preferred way in C++11 is to use the new nullptr keyword, which is implemented in GCC since version 4.6. nullptr is not implicitly convertible to integral types, so it can be used to disambiguate a call to a function which has been overloaded for both pointer and integral types:

void f(int x);
void f(void * ptr);

f(0);  // Passes int 0.
f(nullptr);  // Passes void * 0.

Page unload event in

Refer to the ASP.NET page lifecycle to help find the right event to override. It really depends what you want to do. But yes, there is an unload event.

    protected override void OnUnload(EventArgs e)

        // your code

But just remember (from the above link): During the unload stage, the page and its controls have been rendered, so you cannot make further changes to the response stream. If you attempt to call a method such as the Response.Write method, the page will throw an exception.

How do I run a file on localhost?

I'm not really sure what you mean, so I'll start simply:

If the file you're trying to "run" is static content, like HTML or even Javascript, you don't need to run it on "localhost"... you should just be able to open it from wherever it is on your machine in your browser.

If it is a piece of server-side code (ASP[.NET], php, whatever else, uou need to be running either a web server, or if you're using Visual Studio, start the development server for your application (F5 to debug, or CTRL+F5 to start without debugging).

If you're using a web server, you'll need to have a web site configured with the home directory set to the directory the file is in (or, just put the file in whatever home directory is configured).

If you're using Visual Studio, the file just needs to be in your project.

Enable binary mode while restoring a Database from an SQL dump

Have you tried opening in notepad++ (or another editor) and converting/saving us to UTF-8?

See: notepad++ converting ansi encoded file to utf-8

Another option may be to use textwrangle to open and save the file as UTF-8:

Pretty-Printing JSON with PHP

Classic case for a recursive solution. Here's mine:

class JsonFormatter {
    public static function prettyPrint(&$j, $indentor = "\t", $indent = "") {
        $inString = $escaped = false;
        $result = $indent;

        if(is_string($j)) {
            $bak = $j;
            $j = str_split(trim($j, '"'));

        while(count($j)) {
            $c = array_shift($j);
            if(false !== strpos("{[,]}", $c)) {
                if($inString) {
                    $result .= $c;
                } else if($c == '{' || $c == '[') {
                    $result .= $c."\n";
                    $result .= self::prettyPrint($j, $indentor, $indentor.$indent);
                    $result .= $indent.array_shift($j);
                } else if($c == '}' || $c == ']') {
                    array_unshift($j, $c);
                    $result .= "\n";
                    return $result;
                } else {
                    $result .= $c."\n".$indent;
            } else {
                $result .= $c;
                $c == '"' && !$escaped && $inString = !$inString;
                $escaped = $c == '\\' ? !$escaped : false;

        $j = $bak;
        return $result;


php > require 'JsonFormatter.php';
php > $a = array('foo' => 1, 'bar' => 'This "is" bar', 'baz' => array('a' => 1, 'b' => 2, 'c' => '"3"'));
php > print_r($a);
    [foo] => 1
    [bar] => This "is" bar
    [baz] => Array
            [a] => 1
            [b] => 2
            [c] => "3"

php > echo JsonFormatter::prettyPrint(json_encode($a));
    "bar":"This \"is\" bar",


c# Image resizing to different size while preserving aspect ratio

I just wrote this cos none of the answers already here were simple enough. You can replace the hardcoded 128 for whatever you want or base them off the size of the original image. All i wanted was to rescale the image into a 128x128 image, keeping the aspect ratio and centering the result in the new image.

    private Bitmap CreateLargeIconForImage(Bitmap src)
        Bitmap bmp = new Bitmap(128, 128);
        Graphics g = Graphics.FromImage(bmp);

        float scale = Math.Max((float)src.Width / 128.0f, (float)src.Height / 128.0f);
        PointF p = new PointF(128.0f - ((float)src.Width / scale), 128.0f - ((float)src.Height / scale));
        SizeF size = new SizeF((float)src.Width / scale, (float)src.Height / scale);

        g.DrawImage(src, new RectangleF(p, size));

        return bmp;

Copying a HashMap in Java

If you want a copy of the HashMap you need to construct a new one with.

myobjectListB = new HashMap<Integer,myObject>(myobjectListA);

This will create a (shallow) copy of the map.

Python None comparison: should I use "is" or ==?

is is generally preferred when comparing arbitrary objects to singletons like None because it is faster and more predictable. is always compares by object identity, whereas what == will do depends on the exact type of the operands and even on their ordering.

This recommendation is supported by PEP 8, which explicitly states that "comparisons to singletons like None should always be done with is or is not, never the equality operators."

Counting the number of option tags in a select tag in jQuery

The W3C solution:

var len = document.getElementById("input1").length;

Why do we check up to the square root of a prime number to determine if it is prime?

Let's say m = sqrt(n) then m × m = n. Now if n is not a prime then n can be written as n = a × b, so m × m = a × b. Notice that m is a real number whereas n, a and b are natural numbers.

Now there can be 3 cases:

  1. a > m ? b < m
  2. a = m ? b = m
  3. a < m ? b > m

In all 3 cases, min(a, b) = m. Hence if we search till m, we are bound to find at least one factor of n, which is enough to show that n is not prime.

Can't find/install

EDIT: As mentioned by Stephen Niedzielski in his comment, the issue seems to come from the 32-bit being of the JRE, which is de facto, looking for the 32-bit version of libXtst6. To install the required version of the library:

$ sudo apt-get install libxtst6:i386


$ sudo apt-get update
$ sudo apt-get install libxtst6

If this isn’t OK, type:

$ sudo updatedb
$ locate libXtst

it should return something like:

/usr/lib/x86_64-linux-gnu/       # Mine is OK

If you do not have but do have create a symbolic link:

$ cd /usr/lib/x86_64-linux-gnu/
$ ln -s

Hope this helps.

Change Tomcat Server's timeout in Eclipse

Open the Servers view -> double click tomcat -> drop down the Timeouts section

There you can increase the startup time for each particular server.

`React/RCTBridgeModule.h` file not found

Go to iOS folder in your project and install pod -

$ pod install

If you are getting any error in installation of pod type command-

$ xcode-select -p

Result should be - /Applications/

If the path is incorrect then open your iOS project in Xcode and go to: Xcode->preferences->command line tools-> select Xcode

And again install the pod your issue will be fixed.

How to solve PHP error 'Notice: Array to string conversion in...'

$result = ob_get_clean();

if you want to capture the result in a variable

PuTTY Connection Manager download?

PuTTY Session Manager is a tool that allows system administrators to organise their PuTTY sessions into folders and assign hotkeys to favourite sessions. Multiple sessions can be launched with one click. Requires MS Windows and the .NET 2.0 Runtime.

What's the difference between all the Selection Segues?

For those who prefer a bit more practical learning, select the segue in dock, open the attribute inspector and switch between different kinds of segues (dropdown "Kind"). This will reveal options specific for each of them: for example you can see that "present modally" allows you to choose a transition type etc.

Why is the default value of the string type null instead of an empty string?

Perhaps if you'd use ?? operator when assigning your string variable, it might help you.

string str = SomeMethodThatReturnsaString() ?? "";
// if SomeMethodThatReturnsaString() returns a null value, "" is assigned to str.

java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver

try to add ojdbc6.jar through the server lib "C:\apache-tomcat-7.0.47\lib",

Then restart the server in eclipse.

C# Numeric Only TextBox Control


// Boolean flag used to determine when a character other than a number is entered.
private bool nonNumberEntered = false;
// Handle the KeyDown event to determine the type of character entered into the control.
private void textBox1_KeyDown(object sender, KeyEventArgs e)
    // Initialize the flag to false.
    nonNumberEntered = false;
    // Determine whether the keystroke is a number from the top of the keyboard.
    if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
        // Determine whether the keystroke is a number from the keypad.
        if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
            // Determine whether the keystroke is a backspace.
            if (e.KeyCode != Keys.Back)
                // A non-numerical keystroke was pressed.
                // Set the flag to true and evaluate in KeyPress event.
                nonNumberEntered = true;

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
    if (nonNumberEntered == true)
       MessageBox.Show("Please enter number only..."); 
       e.Handled = true;

Source is

How to expire a cookie in 30 minutes using jQuery?

I had issues getting the above code to work within cookie.js. The following code managed to create the correct timestamp for the cookie expiration in my instance.

var inFifteenMinutes = new Date(new Date().getTime() + 15 * 60 * 1000);

This was from the FAQs for Cookie.js

PHP: How to get referrer URL?

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

CSS white space at bottom of page despite having both min-height and height tag

I had white space at the bottom of all my websites; this is how I solved the matter:

the first and best thing you can do when you are debugging css issues like this is to add:

*{ border: 1px solid red; }

this css line puts a red box around all your css elements.

I had white space at the bottom of my page due to a faulty chrome extension which was adding the div 'dp_swf_engine' to the bottom of my page:

without the red box, I would have never noticed a 1px div. I then got rid of the faulty extension, and put 'display:none' on #dp_swf_engine as a secondary measure. (who knows when it could come back to add random white space at the bottom of my page for all my pages and apps?!)

Order a MySQL table by two columns

This maybe help somebody who is looking for the way to sort table by two columns, but in paralel way. This means to combine two sorts using aggregate sorting function. It's very useful when for example retrieving articles using fulltext search and also concerning the article publish date.

This is only example, but if you catch the idea you can find a lot of aggregate functions to use. You can even weight the columns to prefer one over second. The function of mine takes extremes from both sorts, thus the most valued rows are on the top.

Sorry if there exists simplier solutions to do this job, but I haven't found any.

     @row := @row + 1 as `date_order_id`
         @row := @row + 1 as `match_order_id`
             `art_id` AS `id`,
             `text`   AS `text`,
             `date`   AS `date`,
             MATCH (`text`) AGAINST (:string) AS `match`
             FROM int_art_fulltext
             WHERE MATCH (`text`) AGAINST (:string IN BOOLEAN MODE)
             LIMIT 0,101
         ) t,
           SELECT @row := 0
         ) r
         ORDER BY `match` DESC
     ) k,
       SELECT @row := 0
     ) l
     ORDER BY k.`date` DESC
   ) s
 ORDER BY (1/`match_order_id`+1/`date_order_id`) DESC

How to get address of a pointer in c/c++?

Having this C source:

int a = 10;
int * ptr = &a;

Use this

printf("The address of ptr is %p\n", (void *) &ptr);

to print the address of ptr.

Please note that the conversion specifier p is the only conversion specifier to print a pointer's value and it is defined to be used with void* typed pointers only.

From man printf:


The void * pointer argument is printed in hexadecimal (as if by %#x or %#lx).

C++ passing an array pointer as a function argument

I'm guessing this will help.

When passed as functions arguments, arrays act the same way as pointers. So you don't need to reference them. Simply type: int x[] or int x[a] . Both ways will work. I guess its the same thing Konrad Rudolf was saying, figured as much.

Change the Arrow buttons in Slick slider

if your using react-slick you can try this on custom next and prev divs

REST API - file (ie images) processing - best practices

OP here (I am answering this question after two years, the post made by Daniel Cerecedo was not bad at a time, but the web services are developing very fast)

After three years of full-time software development (with focus also on software architecture, project management and microservice architecture) I definitely choose the second way (but with one general endpoint) as the best one.

If you have a special endpoint for images, it gives you much more power over handling those images.

We have the same REST API (Node.js) for both - mobile apps (iOS/android) and frontend (using React). This is 2017, therefore you don't want to store images locally, you want to upload them to some cloud storage (Google cloud, s3, cloudinary, ...), therefore you want some general handling over them.

Our typical flow is, that as soon as you select an image, it starts uploading on background (usually POST on /images endpoint), returning you the ID after uploading. This is really user-friendly, because user choose an image and then typically proceed with some other fields (i.e. address, name, ...), therefore when he hits "send" button, the image is usually already uploaded. He does not wait and watching the screen saying "uploading...".

The same goes for getting images. Especially thanks to mobile phones and limited mobile data, you don't want to send original images, you want to send resized images, so they do not take that much bandwidth (and to make your mobile apps faster, you often don't want to resize it at all, you want the image that fits perfectly into your view). For this reason, good apps are using something like cloudinary (or we do have our own image server for resizing).

Also, if the data are not private, then you send back to app/frontend just URL and it downloads it from cloud storage directly, which is huge saving of bandwidth and processing time for your server. In our bigger apps there are a lot of terabytes downloaded every month, you don't want to handle that directly on each of your REST API server, which is focused on CRUD operation. You want to handle that at one place (our Imageserver, which have caching etc.) or let cloud services handle all of it.

Cons : The only "cons" which you should think of is "not assigned images". User select images and continue with filling other fields, but then he says "nah" and turn off the app or tab, but meanwhile you successfully uploaded the image. This means you have uploaded an image which is not assigned anywhere.

There are several ways of handling this. The most easiest one is "I don't care", which is a relevant one, if this is not happening very often or you even have desire to store every image user send you (for any reason) and you don't want any deletion.

Another one is easy too - you have CRON and i.e. every week and you delete all unassigned images older than one week.

Pandas conditional creation of a series/dataframe column

One liner with .apply() method is following:

df['color'] = df['Set'].apply(lambda set_: 'green' if set_=='Z' else 'red')

After that, df data frame looks like this:

>>> print(df)
  Type Set  color
0    A   Z  green
1    B   Z  green
2    B   X    red
3    C   Y    red

Create a symbolic link of directory in Ubuntu

In script is usefull something like this:

if [ ! -d /etc/nginx ]; then ln -s /usr/local/nginx/conf/ /etc/nginx > /dev/null 2>&1; fi

it prevents before re-create "bad" looped symlink after re-run script

Moment JS start and end of given month

Try the following code:


What is the difference between task and thread?

A task is something you want done.

A thread is one of the many possible workers which performs that task.

In .NET 4.0 terms, a Task represents an asynchronous operation. Thread(s) are used to complete that operation by breaking the work up into chunks and assigning to separate threads.

Using the "start" command with parameters passed to the started program

Put the command inside a batch file, and call that with the parameters.

Also, did you try this yet? (Move end quote to encapsulate parameters)

start "c:\program files\Microsoft Virtual PC\Virtual PC.exe -pc MY-PC -launch"

How to load a UIView using a nib file created with Interface Builder

I would use UINib to instantiate a custom UIView to be reused

UINib *customNib = [UINib nibWithNibName:@"MyCustomView" bundle:nil];
MyCustomViewClass *customView = [[customNib instantiateWithOwner:self options:nil] objectAtIndex:0];
[self.view addSubview:customView];

Files needed in this case are MyCustomView.xib, MyCustomViewClass.h and MyCustomViewClass.m Note that [UINib instantiateWithOwner] returns an array, so you should use the element which reflects the UIView you want to re-use. In this case it's the first element.

How can I ping a server port with PHP?

You don't need any exec or shell_exec hacks to do that, it is possible to do it in PHP. The book 'You want to do WHAT with PHP?' by Kevin Schroeder, show's how.

It uses sockets and the pack() function which lets you read and write binary protocols. What you need to do is to create an ICMP packet, which you can do by using the 'CCnnnA*' format to create your packet.

Giving graphs a subtitle in matplotlib

This is a pandas code example that implements Floris van Vugt's answer (Dec 20, 2010). He said:

>What I do is use the title() function for the subtitle and the suptitle() for the >main title (they can take different fontsize arguments). Hope that helps!

import pandas as pd
import matplotlib.pyplot as plt

d = {'series a' : pd.Series([1., 2., 3.], index=['a', 'b', 'c']),
      'series b' : pd.Series([1., 2., 3., 4.], index=['a', 'b', 'c', 'd'])}
df = pd.DataFrame(d)

title_string = "This is the title"
subtitle_string = "This is the subtitle"

plt.suptitle(title_string, y=1.05, fontsize=18)
plt.title(subtitle_string, fontsize=10)

Note: I could not comment on that answer because I'm new to stackoverflow.

Convert np.array of type float64 to type uint8 scaling values

Considering that you are using OpenCV, the best way to convert between data types is to use normalize function.

img_n = cv2.normalize(src=img, dst=None, alpha=0, beta=255, norm_type=cv2.NORM_MINMAX, dtype=cv2.CV_8U)

However, if you don't want to use OpenCV, you can do this in numpy

def convert(img, target_type_min, target_type_max, target_type):
    imin = img.min()
    imax = img.max()

    a = (target_type_max - target_type_min) / (imax - imin)
    b = target_type_max - a * imax
    new_img = (a * img + b).astype(target_type)
    return new_img

And then use it like this

imgu8 = convert(img16u, 0, 255, np.uint8)

This is based on the answer that I found on crossvalidated board in comments under this solution

how to clear JTable

I think you meant that you want to clear all the cells in the jTable and make it just like a new blank jTable. For an example, if your table is myTable, you can do following.

DefaultTableModel model = new DefaultTableModel();

Check whether specific radio button is checked


use this and here ClientID fetch random id created by .net.

How to create a number picker dialog?

To show NumberPicker in AlertDialog use this code :

final AlertDialog.Builder d = new AlertDialog.Builder(context);
LayoutInflater inflater = this.getLayoutInflater();
View dialogView = inflater.inflate(R.layout.number_picker_dialog, null);
final NumberPicker numberPicker = (NumberPicker) dialogView.findViewById(;
numberPicker.setOnValueChangedListener(new NumberPicker.OnValueChangeListener() {
    public void onValueChange(NumberPicker numberPicker, int i, int i1) {
        Log.d(TAG, "onValueChange: ");
d.setPositiveButton("Done", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialogInterface, int i) {
        Log.d(TAG, "onClick: " + numberPicker.getValue());
d.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
    public void onClick(DialogInterface dialogInterface, int i) {
AlertDialog alertDialog = d.create();;




How to have conditional elements and keep DRY with Facebook React's JSX?

&& + code-style + small components

This simple test syntax + code-style convention + small focused components is for me the most readable option out there. You just need to take special care of falsy values like false, 0 or "".

render: function() {
    var person= ...; 
    var counter= ...; 
    return (
       <div className="component">
          {person && (
            <Person person={person}/>
          {(typeof counter !== 'undefined') && (
            <Counter value={counter}/>

do notation

ES7 stage-0 do notation syntax is also very nice and I'll definitively use it when my IDE supports it correctly:

const Users = ({users}) => (
    { =>
      <User key={} user={user}/>

const UserList = ({users}) => do {
  if (!users) <div>Loading</div>
  else if (!users.length) <div>Empty</div>
  else <Users users={users}/>

More details here: ReactJs - Creating an "If" component... a good idea?

sql query to get earliest date

If you just want the date:

SELECT MIN(date) as EarliestDate
FROM YourTable
WHERE id = 2

If you want all of the information:

SELECT TOP 1 id, name, score, date
FROM YourTable
WHERE id = 2

Prevent loops when you can. Loops often lead to cursors, and cursors are almost never necessary and very often really inefficient.

What is time_t ultimately a typedef to?

Under Visual Studio 2008, it defaults to an __int64 unless you define _USE_32BIT_TIME_T. You're better off just pretending that you don't know what it's defined as, since it can (and will) change from platform to platform.

How to verify a Text present in the loaded page through WebDriver

Yes, you can do that which returns boolean. The following java code in WebDriver with TestNG or JUnit can do:

protected boolean isTextPresent(String text){
        boolean b = driver.getPageSource().contains(text);
        return b;
    catch(Exception e){
        return false;

Now call the above method as below:

assertTrue(isTextPresent("Your text"));

Or, there is another way. I think, this is the better way:

private StringBuffer verificationErrors = new StringBuffer();
try {
                  assertTrue(driver.findElement(By.cssSelector("BODY")).getText().matches("^[\\s\\S]*    Your text here\r\n\r\n[\\s\\S]*$"));
  } catch (Error e) {

How to force link from iframe to be opened in the parent window

<a target="parent"> will open links in a new tab/window ... <a target="_parent"> will open links in the parent/current window, without opening new tabs/windows. Don't_forget_that_underscore!

Overlaying a DIV On Top Of HTML 5 Video

<div id="video_box">
  <div id="video_overlays"></div>
    <video id="player" src="" type="video/webm" onclick=";">Your browser does not support this streaming content.</video>

for this you need to just add css like this:

#video_overlays {
  position: absolute;
  background-color: rgba(0, 0, 0, 0.46);
  z-index: 2;
  left: 0;
  right: 0;
  top: 0;
  bottom: 0;
#video_box{position: relative;}

How to make the main content div fill height of screen with css

Not sure exactly what your after, but I think I get it.

A header - stays at the top of the screen? A footer - stays at the bottom of the screen? Content area -> fits the space between the footer and the header?

You can do this by absolute positioning or with fixed positioning.

Here is an example with absolute positioning:


<div class="header">Header</div>
<div class="mainbody">Main Body</div>
<div class="footer">Footer</div>


.header {outline:1px solid red; height: 40px; position:absolute; top:0px; width:100%;}
.mainbody {outline:1px solid green; min-height:200px; position:absolute; top:40px; width:100%; height:90%;}
.footer {outline:1px solid blue; height:20px; position:absolute; height:25px;bottom:0; width:100%; } 

To make it work best, I'd suggest using % instead of pixels, as you will run into problems with different screen/device sizes.

How to get config parameters in Symfony2 Twig Templates

You can simply bind $this->getParameter('app.version') in controller to twig param and then render it.

How to search in a List of Java object

Using Java 8

With Java 8 you can simply convert your list to a stream allowing you to write:

import java.util.List;

List<Sample> list = new ArrayList<Sample>();
List<Sample> result =
    .filter(a -> Objects.equals(a.value3, "three"))

Note that

  • a -> Objects.equals(a.value3, "three") is a lambda expression
  • result is a List with a Sample type
  • It's very fast, no cast at every iteration
  • If your filter logic gets heavier, you can do list.parallelStream() instead of (read this)

Apache Commons

If you can't use Java 8, you can use Apache Commons library and write:

import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.Predicate;

Collection result =, new Predicate() {
     public boolean evaluate(Object a) {
         return Objects.equals(((Sample) a).value3, "three");

// If you need the results as a typed array:
Sample[] resultTyped = (Sample[]) result.toArray(new Sample[result.size()]);

Note that:

  • There is a cast from Object to Sample at each iteration
  • If you need your results to be typed as Sample[], you need extra code (as shown in my sample)

Bonus: A nice blog article talking about how to find element in list.

Where is array's length property defined?

Arrays are special objects in java, they have a simple attribute named length which is final.

There is no "class definition" of an array (you can't find it in any .class file), they're a part of the language itself.

10.7. Array Members

The members of an array type are all of the following:

  • The public final field length, which contains the number of components of the array. length may be positive or zero.
  • The public method clone, which overrides the method of the same name in class Object and throws no checked exceptions. The return type of the clone method of an array type T[] is T[].

    A clone of a multidimensional array is shallow, which is to say that it creates only a single new array. Subarrays are shared.

  • All the members inherited from class Object; the only method of Object that is not inherited is its clone method.


jQuery to serialize only elements within a div

You can improve the speed of your code if you restrict the items jQuery will look at.

Use the selector :input instead of * to achieve it.

$('#divId :input').serialize()

This will make your code faster because the list of items is shorter.

Match the path of a URL, minus the filename extension

Regular expression for matching everything after "net" and before ".php":

$pattern = "net([a-zA-Z0-9_]*)\.php"; 

In the above regular expression, you can find the matching group of characters enclosed by "()" to be what you are looking for.

Hope it's useful.

Ruby send JSON request

require 'net/http'
require 'json'

def create_agent
    uri = URI('')
    http =, uri.port)
    req =, 'Content-Type' => 'application/json')
    req.body = {name: 'John Doe', role: 'agent'}.to_json
    res = http.request(req)
    puts "response #{res.body}"
rescue => e
    puts "failed #{e}"

AngularJS - Animate ng-view transitions

Check this code:


app.config( ["$routeProvider"], function($routeProvider){
    $routeProvider.when("/part1", {"templateUrl" : "part1"});
    $routeProvider.when("/part2", {"templateUrl" : "part2"});

function HomeFragmentController($scope) {
    $scope.$on("$routeChangeSuccess", function (scope, next, current) {
        $scope.transitionState = "active"


.fragmentWrapper {
    overflow: hidden;

.fragment {
    position: relative;
    -moz-transition-property: left;
    -o-transition-property: left;
    -webkit-transition-property: left;
    transition-property: left;
    -moz-transition-duration: 0.1s;
    -o-transition-duration: 0.1s;
    -webkit-transition-duration: 0.1s;
    transition-duration: 0.1s

.fragment:not(.active) {
    left: 540px;
} {
    left: 0px;

Main page HTML:

<div class="fragmentWrapper" data-ng-view data-ng-controller="HomeFragmentController">

Partials HTML example:

<div id="part1" class="fragment {{transitionState}}">

Extracting time from POSIXct

The data.table package has a function 'as.ITime', which can do this efficiently use below:

x <- "2012-03-07 03:06:49 CET"
as.IDate(x) # Output is "2012-03-07"
as.ITime(x) # Output is "03:06:49"

C default arguments

Short answer: No.

Slightly longer answer: There is an old, old workaround where you pass a string that you parse for optional arguments:

int f(int arg1, double arg2, char* name, char *opt);

where opt may include "name=value" pair or something, and which you would call like

n = f(2,3.0,"foo","plot=yes save=no");

Obviously this is only occasionally useful. Generally when you want a single interface to a family of functionality.

You still find this approach in particle physics codes that are written by professional programs in c++ (like for instance ROOT). It's main advantage is that it may be extended almost indefinitely while maintaining back compatibility.

Permission denied: /var/www/abc/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable?

Make sure that the htaccess file is readable by apache:

chmod 644 /var/www/abc/.htaccess 

And make sure the directory it's in is readable and executable:

chmod 755 /var/www/abc/

Cannot find "Package Explorer" view in Eclipse

The simplest, and best long-term solution

Go to the main menu on top of Eclipse and locate Window next to Run and expand it.

 Window->Reset Perspective... to restore all views to their defaults

It will reset the default setting.

Returning first x items from array

A more object oriented way would be to provide a range to the #[] method. For instance:

Say you want the first 3 items from an array.

numbers = [1,2,3,4,5,6]

numbers[0..2] # => [1,2,3]

Say you want the first x items from an array.


The great thing about this method is if you ask for more items than the array has, it simply returns the entire array.

numbers[0..100] # => [1,2,3,4,5,6]

How do I change the default index page in Apache?

I recommend using .htaccess. You only need to add:

DirectoryIndex home.php

or whatever page name you want to have for it.

EDIT: basic htaccess tutorial.

1) Create .htaccess file in the directory where you want to change the index file.

  • no extension
  • . in front, to ensure it is a "hidden" file

Enter the line above in there. There will likely be many, many other things you will add to this (AddTypes for webfonts / media files, caching for headers, gzip declaration for compression, etc.), but that one line declares your new "home" page.

2) Set server to allow reading of .htaccess files (may only be needed on your localhost, if your hosting servce defaults to allow it as most do)

Assuming you have access, go to your server's enabled site location. I run a Debian server for development, and the default site setup is at /etc/apache2/sites-available/default for Debian / Ubuntu. Not sure what server you run, but just search for "sites-available" and go into the "default" document. In there you will see an entry for Directory. Modify it to look like this:

<Directory /var/www/>
    Options Indexes FollowSymLinks MultiViews
    AllowOverride None
    Order allow,deny
    allow from all

Then restart your apache server. Again, not sure about your server, but the command on Debian / Ubuntu is:

sudo service apache2 restart

Technically you only need to reload, but I restart just because I feel safer with a full refresh like that.

Once that is done, your site should be reading from your .htaccess file, and you should have a new default home page! A side note, if you have a sub-directory that runs a site (like an admin section or something) and you want to have a different "home page" for that directory, you can just plop another .htaccess file in that sub-site's root and it will overwrite the declaration in the parent.

How do I find an element position in std::vector?

Take a vector of integer and a key (that we find in vector )....Now we are traversing the vector until found the key value or last index(otherwise).....If we found key then print the position , otherwise print "-1".

     #include <bits/stdc++.h>  
     using namespace std;  

     int main()  
          int flag,temp key, ,len,num;


           for(int i=1; i<=len; i++)  


           for(int i=1; i<=len; i++)  

         if(flag!=0)    cout<<temp<<endl;
         else           cout<<"-1"<<endl;   

         return 0;  

How does jQuery work when there are multiple elements with the same ID value?

jQuery's id selector only returns one result. The descendant and multiple selectors in the second and third statements are designed to select multiple elements. It's similar to:

Statement 1

var length = document.getElementById('a').length;

...Yields one result.

Statement 2

var length = 0;
for (i=0; i<document.body.childNodes.length; i++) {
    if (document.body.childNodes.item(i).id == 'a') {

...Yields two results.

Statement 3

var length = document.getElementById('a').length + document.getElementsByTagName('div').length;

...Also yields two results.

Checking if object is empty, works with ng-show but not from controller?

you can check length of items


Short IF - ELSE statement

I'm a little late to the party but for future readers.

From what i can tell, you're just wanting to toggle the visibility state right? Why not just use the ! operator?


It's not an if statement but I prefer this method for code related to your example.

What does java.lang.Thread.interrupt() do?

Thread.interrupt() method sets internal 'interrupt status' flag. Usually that flag is checked by Thread.interrupted() method.

By convention, any method that exists via InterruptedException have to clear interrupt status flag.

use mysql SUM() in a WHERE clause

You can only use aggregates for comparison in the HAVING clause:

  HAVING SUM(cash) > 500

The HAVING clause requires you to define a GROUP BY clause.

To get the first row where the sum of all the previous cash is greater than a certain value, use:

               (SELECT SUM(
                  FROM TABLE x
                 WHERE <= AS running_total
         FROM TABLE t
     ORDER BY y
 WHERE y.running_total > 500
   LIMIT 1

Because the aggregate function occurs in a subquery, the column alias for it can be referenced in the WHERE clause.

Trim spaces from start and end of string

Here is some methods I've been used in the past to trim strings in js:

String.prototype.ltrim = function( chars ) {
    chars = chars || "\\s*";
    return this.replace( new RegExp("^[" + chars + "]+", "g"), "" );

String.prototype.rtrim = function( chars ) {
    chars = chars || "\\s*";
    return this.replace( new RegExp("[" + chars + "]+$", "g"), "" );
String.prototype.trim = function( chars ) {
    return this.rtrim(chars).ltrim(chars);

getting " (1) no such column: _id10 " error

I think you missed a equal sign at:

Cursor c = ourDatabase.query(DATABASE_TABLE, column, KEY_ROWID + "" + l, null, null, null, null);  

Change to:

Cursor c = ourDatabase.query(DATABASE_TABLE, column, KEY_ROWID + " = " + l, null, null, null, null); 

Programmatically add custom event in the iPhone Calendar

Yes there still is no API for this (2.1). But it seemed like at WWDC a lot of people were already interested in the functionality (including myself) and the recommendation was to go to the below site and create a feature request for this. If there is enough of an interest, they might end up moving the ICal.framework to the public SDK.

PHP header() redirect with POST variables

Use a smarty template for your stuff then just set the POST array as a smarty array and open the template. In the template just echo out the array so if it passes:

    header("Location: passed.php");
} else {
    $smarty->assign("variables", $_POST);

I have not tried this yet but I am going to try it as a solution and will let you know what I find. But of course this method assumes that you are using smarty.

If not you can just recreate your form there on the error page and echo info into the form or you could send back non important data in a get from and get it


echo $_GET[name];

How do I specify C:\Program Files without a space in it for programs that can't handle spaces in file paths?

You can just create a folder ProgramFiles at local D or local C to install those apps that can be install to a folder name which has a SPACES / Characters on it.

Bootstrap Alert Auto Close

This is a good approach to show animation in and out using jQuery

  $(document).ready(function() {
      // show the alert
      $(".alert").first().hide().slideDown(500).delay(4000).slideUp(500, function () {

What is the easiest way to disable/enable buttons and links (jQuery + Bootstrap)

I know I'm late to the party, but to specifically answer the two questions:

"I just want to disable specific clicky-things so that:

  • They stop clicking
  • They look disabled

How hard can this be?"

They stop clicking

1.  For buttons like <button> or <input type="button"> you add the attribute: disabled.

<button type="submit" disabled>Register</button>
<input type="button" value="Register" disabled>

2.  For links, ANY link... actually, any HTML element, you can use CSS3 pointer events.

.selector { pointer-events:none; }

Browser support for pointer events is awesome by today's state of the art (5/12/14). But we usually have to support legacy browsers in the IE realm, so IE10 and below DO NOT support pointer events: So using one of the JavaScript solutions mentioned by others here may be the way to go for legacy browsers.

More info about pointer events:

They look disabled

Obviously this a CSS answer, so:

1.  For buttons like <button> or <input type="button"> use the [attribute] selector:

button[disabled] { ... }

input[type=button][disabled] { ... }


Here's a basic demo with the stuff I mentioned here:

Hope this helps.

POST Content-Length exceeds the limit

8388608 bytes is 8M, the default limit in PHP. Those changes to php.ini should indeed solve the problem (make sure your restart your Apache server after making them).

Memory limit shouldn't need to be changed here.

Multi-key dictionary in c#?

Take a look at Wintellect's PowerCollections (CodePlex download). I think their MultiDictionary does something like that.

It's a dictionary of dictionaries, so you have 2 keys to access each object, the key for the main dictionary to get you the required sub dictionary, and then the second key for the sub dictionary to get you the required item. Is that what you mean?

Trigger css hover with JS

You can't. It's not a trusted event.

Events that are generated by the user agent, either as a result of user interaction, or as a direct result of changes to the DOM, are trusted by the user agent with privileges that are not afforded to events generated by script through the DocumentEvent.createEvent("Event") method, modified using the Event.initEvent() method, or dispatched via the EventTarget.dispatchEvent() method. The isTrusted attribute of trusted events has a value of true, while untrusted events have a isTrusted attribute value of false.

Most untrusted events should not trigger default actions, with the exception of click or DOMActivate events.

You have to add a class and add/remove that on the mouseover/mouseout events manually.

Side note, I'm answering this here after I marked this as a duplicate since no answer here really covers the issue from what I see. Hopefully, one day it'll be merged.

Cross-browser bookmark/add to favorites JavaScript

How about using a drop-in solution like ShareThis or AddThis? They have similar functionality, so it's quite possible they already solved the problem.

AddThis's code has a huge if/else browser version fork for saving favorites, though, with most branches ending in prompting the user to manually add the favorite themselves, so I am thinking that no such pure JavaScript implementation exists.

Otherwise, if you only need to support IE and Firefox, you have IE's window.externalAddFavorite( ) and Mozilla's window.sidebar.addPanel( ).

Eclipse DDMS error "Can't bind to local 8600 for debugger"

Try killing port 8600 with this command:

fuser -k 8600/tcp

That fixed it for me.

How to bind a List to a ComboBox?

As you are referring to a combobox, I'm assuming you don't want to use 2-way databinding (if so, look at using a BindingList)

public class Country
    public string Name { get; set; }
    public IList<City> Cities { get; set; }
    public Country(string _name)
        Cities = new List<City>();
        Name = _name;

List<Country> countries = new List<Country> { new Country("UK"), 
                                     new Country("Australia"), 
                                     new Country("France") };

var bindingSource1 = new BindingSource();
bindingSource1.DataSource = countries;

comboBox1.DataSource = bindingSource1.DataSource;

comboBox1.DisplayMember = "Name";
comboBox1.ValueMember = "Name";

To find the country selected in the bound combobox, you would do something like: Country country = (Country)comboBox1.SelectedItem;.

If you want the ComboBox to dynamically update you'll need to make sure that the data structure that you have set as the DataSource implements IBindingList; one such structure is BindingList<T>.

Tip: make sure that you are binding the DisplayMember to a Property on the class and not a public field. If you class uses public string Name { get; set; } it will work but if it uses public string Name; it will not be able to access the value and instead will display the object type for each line in the combo box.

Converting a char to ASCII?

Uhm, what's wrong with this:

#include <iostream>

using namespace std;

int main(int, char **)
    char c = 'A';

    int x = c; // Look ma! No cast!

    cout << "The character '" << c << "' has an ASCII code of " << x << endl;

    return 0;

Configuring Log4j Loggers Programmatically

It sounds like you're trying to use log4j from "both ends" (the consumer end and the configuration end).

If you want to code against the slf4j api but determine ahead of time (and programmatically) the configuration of the log4j Loggers that the classpath will return, you absolutely have to have some sort of logging adaptation which makes use of lazy construction.

public class YourLoggingWrapper {
    private static boolean loggingIsInitialized = false;

    public YourLoggingWrapper() {
        // ...blah

    public static void debug(String debugMsg) {
        log(LogLevel.Debug, debugMsg);

    // Same for all other log levels your want to handle.
    // You mentioned TRACE and ERROR.

    private static void log(LogLevel level, String logMsg) {

        org.slf4j.Logger slf4jLogger = org.slf4j.LoggerFactory.getLogger("DebugLogger");

        switch(level) {
        case: Debug:
            // whatever

    // log4j logging is lazily constructed; it gets initialized
    // the first time the invoking app calls a log method
    private static void initLogging() {
        loggingIsInitialized = true;

        org.apache.log4j.Logger debugLogger = org.apache.log4j.LoggerFactory.getLogger("DebugLogger");

        // Now all the same configuration code that @oers suggested applies...
        // configure the logger, configure and add its appenders, etc.

With this approach, you don't need to worry about where/when your log4j loggers get configured. The first time the classpath asks for them, they get lazily constructed, passed back and made available via slf4j. Hope this helped!

CSS list-style-image size

I'm using:

li {_x000D_
 margin: 0;_x000D_
 padding: 36px 0 36px 84px;_x000D_
 list-style: none;_x000D_
 background-image: url("../../images/checked_red.svg");_x000D_
 background-repeat: no-repeat;_x000D_
 background-position: left center;_x000D_
 background-size: 40px;_x000D_

where background-size set the background image size.

Oracle SqlPlus - saving output in a file but don't show on screen

Try This:

sqlplus -s ${ORA_CONN_STR} <<EOF >/dev/null

Java - No enclosing instance of type Foo is accessible

Declare the INNER class Thing as a static and it will work with no issues.

I remember I have the same issue with the inner class Dog when I declared it as class Dog { only. I got the same issue as you did. There were two solutions:

1- To declare the inner class Dog as static. Or

2- To move the inner class Dog to a new class by itself.

Here is the Example:

public class ReturnDemo {

public static void main(String[] args) {
    int z = ReturnDemo.calculate(10, 12);
    System.out.println("z = " + z);
    ReturnDemo.Dog dog = new Dog("Bosh", " Doggy");
    System.out.println( dog.getDog());

public static int calculate (int x, int y) {
    return x + y;

public void print( ) {
    System.out.println("void method");

public String getString() {
    return "Retrun String type value";

static class Dog {
private String breed;
private String name;

public Dog(String breed, String name) {
    this.breed = breed; = name;

public Dog getDog() {
    // return Dog type;
    return this;

public String toString() {
    return "breed" + breed.concat("name: " + name);


How to get ERD diagram for an existing database?

We used DBVisualizer for that.

Description: The references graph is a great feature as it automatically renders all primary/foreign key mappings (also called referential integrity constraints) in a graph style. The table nodes and relations are layed out automatically, with a number of layout modes available. The resulting graph is unique as it displays all information in an optimal and readable layout. from its site

How do I find out which DOM element has the focus?

I have found the following snippet to be useful when trying to determine which element currently has focus. Copy the following into the console of your browser, and every second it will print out the details of the current element that has focus.

setInterval(function() { console.log(document.querySelector(":focus")); }, 1000);

Feel free to modify the console.log to log out something different to help you pinpoint the exact element if printing out the whole element does not help you pinpoint the element.

Export a list into a CSV or TXT file in R

You can simply wrap your list as a data.frame (data.frame is in fact a special kind of list). Here is an example:

mylist = list() 
mylist[["a"]] = 1:10 
mylist[["b"]] = letters[1:10]
write.table(,file="mylist.csv", quote=F,sep=",",row.names=F)

or alternatively you can use write.csv (a wrapper around write.table). For the conversion of the list , you can use both and data.frame(mylist).

To help in making a reproducible example, you can use functions like dput on your data.

How do I make case-insensitive queries on Mongodb?

An easy way would be to use $toLower as below.

        $project: {
            name: { $toLower: "$name" }
        $match: {
            name: the_name_to_search

Ruby Hash to array of values

hash.collect { |k, v| v }
#returns [["a", "b", "c"], ["b", "c"]] 

Enumerable#collect takes a block, and returns an array of the results of running the block once on every element of the enumerable. So this code just ignores the keys and returns an array of all the values.

The Enumerable module is pretty awesome. Knowing it well can save you lots of time and lots of code.

Android Relative Layout Align Center

You can use gravity with aligning top and bottom.


How do I set specific environment variables when debugging in Visual Studio?

In Visual Studio for Mac and C# you can use:

Environment.SetEnvironmentVariable("<Variable_name>", "<Value>");

But you will need the following namespace

using System.Collections;

you can check the full list of variables with this:

foreach (DictionaryEntry de in Environment.GetEnvironmentVariables())
            Console.WriteLine("  {0} = {1}", de.Key, de.Value);

How to create a directory and give permission in single command

According to mkdir's man page...

mkdir -m 777 dirname

XPath OR operator for different nodes

All title nodes with zipcode or book node as parent:

Version 1:


Version 2:


Version 3: (results are sorted based on source data rather than the order of book then zipcode)

//title[../../../*[book or magazine] or ../../../../*[city/zipcode]]

or - used within true/false - a Boolean operator in xpath

| - a Union operator in xpath that appends the query to the right of the operator to the result set from the left query.

Detect changed input text box

Text inputs do not fire the change event until they lose focus. Click outside of the input and the alert will show.

If the callback should fire before the text input loses focus, use the .keyup() event.

How to get error information when HttpWebRequest.GetResponse() fails

I faced a similar situation:

I was trying to read raw response in case of an HTTP error consuming a SOAP service, using BasicHTTPBinding.

However, when reading the response using GetResponseStream(), got the error:

Stream not readable

So, this code worked for me:

    response = basicHTTPBindingClient.CallOperation(request);
catch (ProtocolException exception)
    var webException = exception.InnerException as WebException;
    var rawResponse = string.Empty;

    var alreadyClosedStream = webException.Response.GetResponseStream() as MemoryStream;
    using (var brandNewStream = new MemoryStream(alreadyClosedStream.ToArray()))
    using (var reader = new StreamReader(brandNewStream))
        rawResponse = reader.ReadToEnd();

Difference between 'cls' and 'self' in Python classes?

Instead of accepting a self parameter, class methods take a cls parameter that points to the class—and not the object instance—when the method is called. Since the class method only has access to this cls argument, it can’t modify object instance state. That would require access to self . However, class methods can still modify class state that applies across all instances of the class.

-Python Tricks

Getting Index of an item in an arraylist;

Rather than a brute force loop through the list (eg 1 to 10000), rather use an iterative search approach : The List needs to be sorted by the element to be tested.

Start search at the middle element size()/2 eg 5000 if search item greater than element at 5000, then test the element at the midpoint between the upper(10000) and midpoint(5000) - 7500

keep doing this until you reach the match (or use a brute force loop through once you get down to a smaller range (eg 20 items)

You can search a list of 10000 in around 13 to 14 tests, rather than potentially 9999 tests.

require is not defined? Node.js

This can now also happen in Node.js as of version 14.

It happens when you declare your package type as module in your package.json. If you do this, certain CommonJS variables can't be used, including require.

To fix this, remove "type": "module" from your package.json and make sure you don't have any files ending with .mjs.

How to ALTER multiple columns at once in SQL Server

If you do the changes in management studio and generate scripts it makes a new table and inserts the old data into that with the changed data types. Here is a small example changing two column’s data types

   12 August 201008:30:39
   Database: Tracker_3

/* To prevent any potential data loss issues, you should review this script in detail before running it outside the context of the database designer.*/
ALTER TABLE dbo.tblDiary
    DROP CONSTRAINT FK_tblDiary_tblDiary_events
CREATE TABLE dbo.Tmp_tblDiary
    Diary_ID int NOT NULL IDENTITY (1, 1),
    Date date NOT NULL,
    Diary_event_type_ID int NOT NULL,
    Notes varchar(MAX) NULL,
    Expected_call_volumes real NULL,
    Expected_duration real NULL,
    Skill_affected smallint NULL
    )  ON T3_Data_2
     TEXTIMAGE_ON T3_Data_2
     EXEC('INSERT INTO dbo.Tmp_tblDiary (Diary_ID, Date, Diary_event_type_ID, Notes, Expected_call_volumes, Expected_duration, Skill_affected)
        SELECT Diary_ID, Date, Diary_event_type_ID, CONVERT(varchar(MAX), Notes), Expected_call_volumes, Expected_duration, CONVERT(smallint, Skill_affected) FROM dbo.tblDiary WITH (HOLDLOCK TABLOCKX)')
DROP TABLE dbo.tblDiary
EXECUTE sp_rename N'dbo.Tmp_tblDiary', N'tblDiary', 'OBJECT' 

CREATE NONCLUSTERED INDEX tblDiary_date ON dbo.tblDiary
    FK_tblDiary_tblDiary_events FOREIGN KEY
    ) REFERENCES dbo.tblDiary_events


<script> tag vs <script type = 'text/javascript'> tag

Douglas Crockford says:


This attribute is optional. Since Netscape 2, the default programming language in all browsers has been JavaScript. In XHTML, this attribute is required and unnecessary. In HTML, it is better to leave it out. The browser knows what to do.

In HTML 4.01 and XHTML 1(.1), the type attribute for <script> elements is required.

Find what 2 numbers add to something and multiply to something

Come on guys, there is no need to loop, just use simple math to solve this equation system:

a*b = i;

a+b = j;

a = j/b;

a = i-b;

j/b = i-b; so:

b + j/b + i = 0

b^2 + i*b + j = 0

From here, its a quadratic equation, and it's trivial to find b (just implement the quadratic equation formula) and from there get the value for a.


There you go:

function finder($add,$product)

 $inside_root = $add*$add - 4*$product;

 if($inside_root >=0)

     $b = ($add + sqrt($inside_root))/2;
     $a = $add - $b;

     echo "$a+$b = $add and $a*$b=$product\n";

   echo "No real solution\n";

Real live action:

How do I do pagination in ASP.NET MVC?

Well, what is the data source? Your action could take a few defaulted arguments, i.e.

ActionResult Search(string query, int startIndex, int pageSize) {...}

defaulted in the routes setup so that startIndex is 0 and pageSize is (say) 20:

        routes.MapRoute("Search", "Search/{query}/{startIndex}",
                            controller = "Home", action = "Search",
                            startIndex = 0, pageSize = 20

To split the feed, you can use LINQ quite easily:

var page = source.Skip(startIndex).Take(pageSize);

(or do a multiplication if you use "pageNumber" rather than "startIndex")

With LINQ-toSQL, EF, etc - this should "compose" down to the database, too.

You should then be able to use action-links to the next page (etc):

<%=Html.ActionLink("next page", "Search", new {
                query, startIndex = startIndex + pageSize, pageSize }) %>

How to auto-scroll to end of div when data is added?

var objDiv = document.getElementById("divExample");
objDiv.scrollTop = objDiv.scrollHeight;

html script src="" triggering redirection with button

First you are linking the file that is here:

<script src="../Script/login.js"> 

Which would lead the website to a file in the Folder Script, but then in the second paragraph you are saying that the folder name is

and also i have onother folder named scripts that contains the the following login.js file

So, this won't work! Because you are not accessing the correct file. To do that please write the code as

<script src="/script/login.js"></script>

Try removing the .. from the beginning of the code too.

This way, you'll reach the js file where the function would run!

Just to make sure:

Just to make sure that the files are attached the HTML DOM, then please open Developer Tools (F12) and in the network workspace note each request that the browser makes to the server. This way you will learn which files were loaded and which weren't, and also why they were not!

Good luck.

Add views below toolbar in CoordinatorLayout

I managed to fix this by adding:


to the FrameLayout like so:


Python find elements in one list that are not in the other

Not sure why the above explanations are so complicated when you have native methods available:

main_list = list(set(list_2)-set(list_1))

How to execute UNION without sorting? (SQL)

I assume your tables are table1 and table2 respectively, and your solution is;

(select * from table1 MINUS select * from table2)
(select * from table2 MINUS select * from table1)

How do I instantiate a Queue object in java?

Queue is an interface. You can't instantiate an interface directly except via an anonymous inner class. Typically this isn't what you want to do for a collection. Instead, choose an existing implementation. For example:

Queue<Integer> q = new LinkedList<Integer>();


Queue<Integer> q = new ArrayDeque<Integer>();

Typically you pick a collection implementation by the performance and concurrency characteristics you're interested in.

Edit a specific Line of a Text File in C#

When you create a StreamWriter it always create a file from scratch, you will have to create a third file and copy from target and replace what you need, and then replace the old one. But as I can see what you need is XML manipulation, you might want to use XmlDocument and modify your file using Xpath.

CSS Calc Viewport Units Workaround?

Doing this with a CSS Grid is pretty easy. The trick is to set the grid's height to 100vw, then assign one of the rows to 75vw, and the remaining one (optional) to 1fr. This gives you, from what I assume is what you're after, a ratio-locked resizing container.

Example here:

You can even utilize the bottom gutter space if you so choose, simply by adding another "item".

Edit: StackOverflow's built-in code runner has some side effects. Pop over to the codesandbox link and you'll see the ratio in action.

body {_x000D_
  margin: 0;_x000D_
  padding: 0;_x000D_
  background-color: #334;_x000D_
  color: #eee;_x000D_
.main {_x000D_
  min-height: 100vh;_x000D_
  min-width: 100vw;_x000D_
  display: grid;_x000D_
  grid-template-columns: 100%;_x000D_
  grid-template-rows: 75vw 1fr;_x000D_
.item {_x000D_
  background-color: #558;_x000D_
  padding: 2px;_x000D_
  margin: 1px;_x000D_
.item.dead {_x000D_
  background-color: transparent;_x000D_
    <title>Parcel Sandbox</title>_x000D_
    <meta charset="UTF-8" />_x000D_
    <link rel="stylesheet" href="src/index.css" />_x000D_
    <div id="app">_x000D_
      <div class="main">_x000D_
        <div class="item">Item 1</div>_x000D_
        <!-- <div class="item dead">Item 2 (dead area)</div> -->_x000D_

How to Run Terminal as Administrator on Mac Pro

search for terminal after opening the termincal type

su <admin-user-name>   //su - switch user

enter and then give the admin password then run your sudo commands e.g:

sudo open

How to recover stashed uncommitted changes

git stash pop

will get everything back in place

as suggested in the comments, you can use git stash branch newbranch to apply the stash to a new branch, which is the same as running:

git checkout -b newbranch
git stash pop

Can I save input from form to .txt in HTML, using JAVASCRIPT/jQuery, and then use it?

You cannot save it as local file without using server side logic. But if that fits your needs, you could look at local storage of html5 or us a javascript plugin as jStorage

Excel VBA - Delete empty rows

How about

sub foo()
  dim r As Range, rows As Long, i As Long
  Set r = ActiveSheet.Range("A1:Z50")
  rows = r.rows.Count
  For i = rows To 1 Step (-1)
    If WorksheetFunction.CountA(r.rows(i)) = 0 Then r.rows(i).Delete
End Sub

Try this

Option Explicit

Sub Sample()
    Dim i As Long
    Dim DelRange As Range

    On Error GoTo Whoa

    Application.ScreenUpdating = False

    For i = 1 To 50
        If Application.WorksheetFunction.CountA(Range("A" & i & ":" & "Z" & i)) = 0 Then
            If DelRange Is Nothing Then
                Set DelRange = Range("A" & i & ":" & "Z" & i)
                Set DelRange = Union(DelRange, Range("A" & i & ":" & "Z" & i))
            End If
        End If
    Next i

    If Not DelRange Is Nothing Then DelRange.Delete shift:=xlUp
    Application.ScreenUpdating = True

    Exit Sub
    MsgBox Err.Description
    Resume LetsContinue
End Sub

IF you want to delete the entire row then use this code

Option Explicit

Sub Sample()
    Dim i As Long
    Dim DelRange As Range

    On Error GoTo Whoa

    Application.ScreenUpdating = False

    For i = 1 To 50
        If Application.WorksheetFunction.CountA(Range("A" & i & ":" & "Z" & i)) = 0 Then
            If DelRange Is Nothing Then
                Set DelRange = Rows(i)
                Set DelRange = Union(DelRange, Rows(i))
            End If
        End If
    Next i

    If Not DelRange Is Nothing Then DelRange.Delete shift:=xlUp
    Application.ScreenUpdating = True

    Exit Sub
    MsgBox Err.Description
    Resume LetsContinue
End Sub

What is android:ems attribute in Edit Text?

Taken from:

The em is simply the font size. In an element with a 2in font, 1em thus means 2in. Expressing sizes, such as margins and paddings, in em means they are related to the font size, and if the user has a big font (e.g., on a big screen) or a small font (e.g., on a handheld device), the sizes will be in proportion. Declarations such as 'text-indent: 1.5em' and 'margin: 1em' are extremely common in CSS.

em is basically CSS property for font sizes.

How do I verify/check/test/validate my SSH passphrase?

You can verify your SSH key passphrase by attempting to load it into your SSH agent. With OpenSSH this is done via ssh-add.

Once you're done, remember to unload your SSH passphrase from the terminal by running ssh-add -d.

Parsing huge logfiles in Node.js - read in line-by-line

I really liked @gerard answer which is actually deserves to be the correct answer here. I made some improvements:

  • Code is in a class (modular)
  • Parsing is included
  • Ability to resume is given to the outside in case there is an asynchronous job is chained to reading the CSV like inserting to DB, or a HTTP request
  • Reading in chunks/batche sizes that user can declare. I took care of encoding in the stream too, in case you have files in different encoding.

Here's the code:

'use strict'

const fs = require('fs'),
    util = require('util'),
    stream = require('stream'),
    es = require('event-stream'),
    parse = require("csv-parse"),
    iconv = require('iconv-lite');

class CSVReader {
  constructor(filename, batchSize, columns) {
    this.reader = fs.createReadStream(filename).pipe(iconv.decodeStream('utf8'))
    this.batchSize = batchSize || 1000
    this.lineNumber = 0 = []
    this.parseOptions = {delimiter: '\t', columns: true, escape: '/', relax: true}

  read(callback) {
      .pipe(es.mapSync(line => {

        parse(line, this.parseOptions, (err, d) => {

        if (this.lineNumber % this.batchSize === 0) {
      .on('error', function(){
          console.log('Error while reading file.')
      .on('end', function(){
          console.log('Read entirefile.')

  continue () { = []

module.exports = CSVReader

So basically, here is how you will use it:

let reader = CSVReader('path_to_file.csv') => reader.continue())

I tested this with a 35GB CSV file and it worked for me and that's why I chose to build it on @gerard's answer, feedbacks are welcomed.

How do I programmatically click on an element in JavaScript?

For firefox links appear to be "special". The only way I was able to get this working was to use the createEvent described here on MDN and call the initMouseEvent function. Even that didn't work completely, I had to manually tell the browser to open a link...

var theEvent = document.createEvent("MouseEvent");
theEvent.initMouseEvent("click", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
var element = document.getElementById('link');

while (element)
    if (element.tagName == "A" && element.href != "")
        if ( == "_blank") {,; }
        else { document.location = element.href; }
        element = null;
        element = element.parentElement;

Webdriver Unable to connect to host on port 7055 after 45000 ms

Installed Firefox Setup 18.0.exe it works for me

Using jQuery to build table rows from AJAX response(json)

You could do it something like this:

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="">

<!-- jQuery library -->
<script src=""></script>

<!-- Latest compiled JavaScript -->
<script src=""></script>


    url: '<Insert your REST API which you want GET/POST/PUT/DELETE>',
    data: '<any parameters you want to send as the Request body or query string>',
    dataType: json,
    async: true,
    method: "GET"
    success: function(data){

    //If the REST API returned a successful response it'll be stored in data, 
    //just parse that field using jQuery and you're all set

    var tblSomething = '<thead> <tr> <td> Heading Col 1 </td> <td> Heading Col 2 </td> <td> Col 3 </td> </tr> </thead> <tbody>';

    $.each(data, function(idx, obj){

    //Outer .each loop is for traversing the JSON rows
    tblSomething += '<tr>';

    //Inner .each loop is for traversing JSON columns
    $.each(obj, function(key, value){
    tblSomething += '<td>' + value + '</td>';
    tblSomething += '</tr>';

    tblSomething += '</tbody>';

    error: function(jqXHR, textStatus, errorThrown){
    alert('Hey, something went wrong because: ' + errorThrown);


    <table id = "tblSomething" class = "table table-hover"></table>

Press Enter to move to next control

You could also write your own Control for this, in case you want to use this more often. Assuming you have multiple TextBoxes in a Grid, it would look something like this:

public class AdvanceOnEnterTextBox : UserControl

    TextBox _TextBox;
    public static readonly DependencyProperty TextProperty = DependencyProperty.Register("Text", typeof(String), typeof(AdvanceOnEnterTextBox), null);
    public static readonly DependencyProperty InputScopeProperty = DependencyProperty.Register("InputScope", typeof(InputScope), typeof(AdvanceOnEnterTextBox), null);

    public AdvanceOnEnterTextBox()
        _TextBox = new TextBox();
        _TextBox.KeyDown += customKeyDown;
        Content = _TextBox;


    /// <summary>
    /// Text for the TextBox
    /// </summary>
    public String Text
        get { return _TextBox.Text; }
        set { _TextBox.Text = value; }

    /// <summary>
    /// Inputscope for the Custom Textbox
    /// </summary>
    public InputScope InputScope
        get { return _TextBox.InputScope; }
        set { _TextBox.InputScope = value; }

    void customKeyDown(object sender, KeyEventArgs e)
        if (!e.Key.Equals(Key.Enter)) return;

        var element = ((TextBox)sender).Parent as AdvanceOnEnterTextBox;
        if (element != null)
            int currentElementPosition = ((Grid)element.Parent).Children.IndexOf(element);
                // Jump to the next AdvanceOnEnterTextBox (assuming, that Labels are inbetween).
                ((AdvanceOnEnterTextBox)((Grid)element.Parent).Children.ElementAt(currentElementPosition + 2)).Focus();
            catch (Exception)
                // Close Keypad if this was the last AdvanceOnEnterTextBox
                ((AdvanceOnEnterTextBox)((Grid)element.Parent).Children.ElementAt(currentElementPosition)).IsEnabled = false;
                ((AdvanceOnEnterTextBox)((Grid)element.Parent).Children.ElementAt(currentElementPosition)).IsEnabled = true;

finding and replacing elements in a list

You can simply use list comprehension in python:

def replace_element(YOUR_LIST, set_to=NEW_VALUE):
    return [i
            if SOME_CONDITION
            else NEW_VALUE
            for i in YOUR_LIST]

for your case, where you want to replace all occurrences of 1 with 10, the code snippet will be like this:

def replace_element(YOUR_LIST, set_to=10):
    return [i
            if i != 1  # keeps all elements not equal to one
            else set_to  # replaces 1 with 10
            for i in YOUR_LIST]

MySql Query Replace NULL with Empty String in Select

Try this, this should also get rid of those empty lines also:

SELECT prereq FROM test WHERE prereq IS NOT NULL;

What key in windows registry disables IE connection parameter "Automatically Detect Settings"?

Another way to control this setting is by using an undocumented registry key AutoDetect=0 mentioned on this blog post:

Registry Key : HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings\

DWORD AutoDetect = 0 or 1

So the .reg file to turn it off would look like:

Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings]

Global Events in Angular

Service Events: Components can subscribe to service events. For example, two sibling components can subscribe to the same service event and respond by modifying their respective models. More on this below.

But make sure to unsubscribe to that on destroy of the parent component.

How to return value from function which has Observable subscription inside?

Observable values can be retrieved from any locations. The source sequence is first pushed onto a special observer that is able to emit elsewhere. This is achieved with the Subject class from the Reactive Extensions (RxJS).

var subject = new Rx.AsyncSubject();  // store-last-value method

Store value onto the observer.; // store value
subject.complete(); // publish only when sequence is completed

To retrieve the value from elsewhere, subscribe to the observer like so:

  next: (response) => {
      //do stuff. The property name "response" references the value

Subjects are both Observables and Observers. There are other Subject types such as BehaviourSubject and ReplaySubject for other usage scenarios.

Don't forget to import RxJS.

var Rx = require('rxjs');

Why, Fatal error: Class 'PHPUnit_Framework_TestCase' not found in ...?

I was running PHPUnit tests on PHP5, and then, I needed to support PHP7 as well. This is what I did:

In composer.json:

"phpunit/phpunit": "~4.8|~5.7"

In my PHPUnit bootstrap file (in my case, /tests/bootstrap.php):

// PHPUnit 6 introduced a breaking change that
// removed PHPUnit_Framework_TestCase as a base class,
// and replaced it with \PHPUnit\Framework\TestCase
if (!class_exists('\PHPUnit_Framework_TestCase') && class_exists('\PHPUnit\Framework\TestCase'))
    class_alias('\PHPUnit\Framework\TestCase', '\PHPUnit_Framework_TestCase');

In other words, this will work for tests written originally for PHPUnit 4 or 5, but then needed to work on PHPUnit 6 as well.

Convert JSON array to an HTML table in jQuery

Converting a 2D JavaScript array to an HTML table

To turn a 2D JavaScript array into an HTML table, you really need but a little bit of code :

function arrayToTable(tableData) {_x000D_
    var table = $('<table></table>');_x000D_
    $(tableData).each(function (i, rowData) {_x000D_
        var row = $('<tr></tr>');_x000D_
        $(rowData).each(function (j, cellData) {_x000D_
    return table;_x000D_
<script src=""></script>

Loading a JSON file

If you want to load your 2D array from a JSON file, you'll also need a little bit of Ajax code :

    type: "GET",
    url: "data.json",
    dataType: 'json',
    success: function (data) {

GridView sorting: SortDirection always Ascending

void dg_SortCommand(object source, DataGridSortCommandEventArgs e)
    DataGrid dg = (DataGrid) source;
    string sortField = dg.Attributes["sortField"];
    List < SubreportSummary > data = (List < SubreportSummary > ) dg.DataSource;
    string field = e.SortExpression.Split(' ')[0];
    string sort = "ASC";
    if (sortField != null)
        sort = sortField.Split(' ')[0] == field ? (sortField.Split(' ')[1] == "DESC" ? "ASC" : "DESC") : "ASC";
    dg.Attributes["sortField"] = field + " " + sort;
    data.Sort(new GenericComparer < SubreportSummary > (field, sort, null));
    dg.DataSource = data;

How to retrieve Key Alias and Key Password for signed APK in android studio(migrated from Eclipse)

You can find your keystore details without using password as following way.

Execute the command (keytool -list -keystore <path>) in command prompt

You can find the Keytool in java folder in my machine I could find form the following path

C:\Program Files (x86)\Java\jdk1.7.0_71\bin> keytool -list -keystore C:\<YourKeystore>.Keystore

Then it will ask you to enter the password, Here you don't need to enter the password instead of that press up arrow button and enter it. then the same details will be display with warning message as below.

***************** WARNING WARNING WARNING *****************

  • The integrity of the information stored in your keystore *

  • has NOT been verified! In order to verify its integrity, *

  • you must provide your keystore password. *

***************** WARNING WARNING WARNING *****************

Keystore type: JKS Keystore provider: SUN

Your keystore contains 1 entry

samplekey, Apr 26, 2017, PrivateKeyEntry, Certificate fingerprint (SHA1): XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX

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

update mytable set title=trim(replace(REPLACE(title,CHAR(13),''),CHAR(10),''));

Above is working for fine.

Login to Microsoft SQL Server Error: 18456

For me, it was wrong login and password.

How to get DATE from DATETIME Column in SQL?

Try this:

SELECT SUM(transaction_amount) FROM TransactionMaster WHERE Card_No ='123' AND CONVERT(VARCHAR(10),GETDATE(),111)

The GETDATE() function returns the current date and time from the SQL Server.

Does hosts file exist on the iPhone? How to change it?

This doesn't directly answer your question, but it does solve your problem...

What make of router do you have? Your router firmware may allow you to set DNS records for your local network. This is what I do with the Tomato firmware

Best C/C++ Network Library

Aggregated List of Libraries

"The breakpoint will not currently be hit. The source code is different from the original version." What does this mean?

My issue was a bit stupid. I had two copy of my project and I mixed files in visual studio.

Let s say you have projectX and projectY. These projects both contain myFile.cs. I opened projectX and edited myFile.cs. But this myFile.cs was belong to projectY . (It s possible to open files from different projects in visual studio) So in that case as warning says source code will be different than original.

Changing PowerShell's default output encoding to UTF-8

To be short, use:

write-output "your text" | out-file -append -encoding utf8 "filename"

Singleton in Android

As @Lazy stated in this answer, you can create a singleton from a template in Android Studio. It is worth noting that there is no need to check if the instance is null because the static ourInstance variable is initialized first. As a result, the singleton class implementation created by Android Studio is as simple as following code:

public class MySingleton {
    private static MySingleton ourInstance = new MySingleton();

    public static MySingleton getInstance() {
        return ourInstance;

    private MySingleton() {

Restoring database from .mdf and .ldf files of SQL Server 2008

First google search yielded me this answer. So I thought of updating this with newer version of attach, detach.

Create database dbname 
Filename= 'path where you copied files',   
Filename ='path where you copied log'
For attach; 

Further,if your database is cleanly shutdown(there are no active transactions while database was shutdown) and you dont have log file,you can use below method,SQL server will create a new transaction log file..

Create database dbname 
    Filename= 'path where you copied files'   
    For attach; 

if you don't specify transaction log file,SQL will try to look in the default path and will try to use it irrespective of whether database was cleanly shutdown or not..

Here is what MSDN has to say about this..

If a read-write database has a single log file and you do not specify a new location for the log file, the attach operation looks in the old location for the file. If it is found, the old log file is used, regardless of whether the database was shut down cleanly. However, if the old log file is not found and if the database was shut down cleanly and has no active log chain, the attach operation attempts to build a new log file for the database.

There are some restrictions with this approach and some side affects too..

1.attach-and-detach operations both disable cross-database ownership chaining for the database
2.Database trustworthy is set to off
3.Detaching a read-only database loses information about the differential bases of differential backups.

Most can't attach a database with recent versions to an earlier version


If Python is interpreted, what are .pyc files?

Python (at least the most common implementation of it) follows a pattern of compiling the original source to byte codes, then interpreting the byte codes on a virtual machine. This means (again, the most common implementation) is neither a pure interpreter nor a pure compiler.

The other side of this is, however, that the compilation process is mostly hidden -- the .pyc files are basically treated like a cache; they speed things up, but you normally don't have to be aware of them at all. It automatically invalidates and re-loads them (re-compiles the source code) when necessary based on file time/date stamps.

About the only time I've seen a problem with this was when a compiled bytecode file somehow got a timestamp well into the future, which meant it always looked newer than the source file. Since it looked newer, the source file was never recompiled, so no matter what changes you made, they were ignored...

What is the difference between children and childNodes in JavaScript?

Good answers so far, I want to only add that you could check the type of a node using nodeType:


This will give you an integer: (taken from here)

| Value |             Constant             |                          Description                          |  |
|    1  | Node.ELEMENT_NODE                | An Element node such as <p> or <div>.                         |  |
|    2  | Node.ATTRIBUTE_NODE              | An Attribute of an Element. The element attributes            |  |
|       |                                  | are no longer implementing the Node interface in              |  |
|       |                                  | DOM4 specification.                                           |  |
|    3  | Node.TEXT_NODE                   | The actual Text of Element or Attr.                           |  |
|    4  | Node.CDATA_SECTION_NODE          | A CDATASection.                                               |  |
|    5  | Node.ENTITY_REFERENCE_NODE       | An XML Entity Reference node. Removed in DOM4 specification.  |  |
|    6  | Node.ENTITY_NODE                 | An XML <!ENTITY ...> node. Removed in DOM4 specification.     |  |
|    7  | Node.PROCESSING_INSTRUCTION_NODE | A ProcessingInstruction of an XML document                    |  |
|       |                                  | such as <?xml-stylesheet ... ?> declaration.                  |  |
|    8  | Node.COMMENT_NODE                | A Comment node.                                               |  |
|    9  | Node.DOCUMENT_NODE               | A Document node.                                              |  |
|   10  | Node.DOCUMENT_TYPE_NODE          | A DocumentType node e.g. <!DOCTYPE html> for HTML5 documents. |  |
|   11  | Node.DOCUMENT_FRAGMENT_NODE      | A DocumentFragment node.                                      |  |
|   12  | Node.NOTATION_NODE               | An XML <!NOTATION ...> node. Removed in DOM4 specification.   |  |

Note that according to Mozilla:

The following constants have been deprecated and should not be used anymore: Node.ATTRIBUTE_NODE, Node.ENTITY_REFERENCE_NODE, Node.ENTITY_NODE, Node.NOTATION_NODE

Use of def, val, and var in scala

Let's take this:

class Person(val name:String,var age:Int )
def person =new Person("Kumar",12)

and rewrite it with equivalent code

class Person(val name:String,var age:Int )
def person =new Person("Kumar",12)
(new Person("Kumar", 12)).age_=(20)
println((new Person("Kumar", 12)).age)

See, def is a method. It will execute each time it is called, and each time it will return (a) new Person("Kumar", 12). And these is no error in the "assignment" because it isn't really an assignment, but just a call to the age_= method (provided by var).

Highlight a word with jQuery

Why using a selfmade highlighting function is a bad idea

The reason why it's probably a bad idea to start building your own highlighting function from scratch is because you will certainly run into issues that others have already solved. Challenges:

  • You would need to remove text nodes with HTML elements to highlight your matches without destroying DOM events and triggering DOM regeneration over and over again (which would be the case with e.g. innerHTML)
  • If you want to remove highlighted elements you would have to remove HTML elements with their content and also have to combine the splitted text-nodes for further searches. This is necessary because every highlighter plugin searches inside text nodes for matches and if your keywords will be splitted into several text nodes they will not being found.
  • You would also need to build tests to make sure your plugin works in situations which you have not thought about. And I'm talking about cross-browser tests!

Sounds complicated? If you want some features like ignoring some elements from highlighting, diacritics mapping, synonyms mapping, search inside iframes, separated word search, etc. this becomes more and more complicated.

Use an existing plugin

When using an existing, well implemented plugin, you don't have to worry about above named things. The article 10 jQuery text highlighter plugins on Sitepoint compares popular highlighter plugins. This includes plugins of answers from this question.

Have a look at mark.js

mark.js is such a plugin that is written in pure JavaScript, but is also available as jQuery plugin. It was developed to offer more opportunities than the other plugins with options to:

  • search for keywords separately instead of the complete term
  • map diacritics (For example if "justo" should also match "justò")
  • ignore matches inside custom elements
  • use custom highlighting element
  • use custom highlighting class
  • map custom synonyms
  • search also inside iframes
  • receive not found terms


Alternatively you can see this fiddle.

Usage example:

// Highlight "keyword" in the specified context

// Highlight the custom regular expression in the specified context

It's free and developed open-source on GitHub (project reference).

Use Expect in a Bash script to provide a password to an SSH command

Use the helper tool fd0ssh (from hxtools, not pmt). It works without having to expect a particular prompt from the ssh program.

Facebook Graph API, how to get users email?

The email in the profile can be obtained using extended permission but I Guess it's not possible to get the email used to login fb. In my app i wanted to display mulitple fb accounts of a user in a list, i wanted to show the login emails of fb accounts as a unique identifier of the respective accounts but i couldn't get it off from fb, all i got was the primary email in the user profile but in my case my login email and my primary email are different.

random.seed(): What does it do?

>>> random.seed(9001)   
>>> random.randint(1, 10)  
>>> random.seed(9001)     
>>> random.randint(1, 10)    
>>> random.seed(9001)          
>>> random.randint(1, 10)                 
>>> random.seed(9001)         
>>> random.randint(1, 10)          
>>> random.seed(9002)                
>>> random.randint(1, 10)             

You try this.

Let's say 'random.seed' gives a value to random value generator ('random.randint()') which generates these values on the basis of this seed. One of the must properties of random numbers is that they should be reproducible. When you put same seed, you get the same pattern of random numbers. This way you are generating them right from the start. You give a different seed- it starts with a different initial (above 3).

Given a seed, it will generate random numbers between 1 and 10 one after another. So you assume one set of numbers for one seed value.

How should the ViewModel close the form?

Ok, so this question is nearly 6 years old and I still can't find in here what I think it's the proper answer, so allow me to share my "2 cents"...

I actually have 2 ways of doing it, first one is the simple one...the second on the right one, so if you are looking for the right one, just skip #1 and jump to #2:

1. Quick and Easy (but not complete)

If I have just a small project I sometimes just create a CloseWindowAction in the ViewModel:

        public Action CloseWindow { get; set; } // In MyViewModel.cs

And whoever crates the View, or in the View's code behind I just set the Method the Action will call:

(remember MVVM is about separation of the View and the ViewModel...the View's code behins is still the View and as long as there is proper separation you are not violating the pattern)

If some ViewModel creates a new window:

private void CreateNewView()
    MyView window = new MyView();
    window.DataContext = new MyViewModel
                                 CloseWindow = window.Close,

Or if you want it in your Main Window, just place it under your View's constructor:

public MyView()
    this.DataContext = new MainViewModel
                                CloseWindow = this.Close

when you want to close the window, just call the Action on your ViewModel.

2. The right way

Now the proper way of doing it is using Prism (IMHO), and all about it can be found here.

You can make an Interaction Request, populate it with whatever data you will need in your new Window, lunch it, close it and even receive data back. All of this encapsulated and MVVM approved. You even get a status of how the Window was closed, like if the User Canceled or Accepted (OK button) the Window and data back if you need it. It's a bit more complicated and Answer #1, but it's a lot more complete, and a Recommended Pattern by Microsoft.

The link I gave have all the code snippets and examples, so I won't bother to place any code in here, just read the article of download the Prism Quick Start and run it, it's really simple to understad just a little more verbose to make it work, but the benefits are bigger than just closing a window.

changing textbox border colour using javascript

document.getElementById("fName").style.border="1px solid black";

How to compare binary files to check if they are the same?

Use cmp command. This will either exit cleanly if they are binary equal, or it will print out where the first difference occurs and exit.

JavaScript for handling Tab Key press

Having following html:

<!-- note that not all browsers focus on links when Tab is pressed -->
<a href="">Link</a>

<input type="text" placeholder="Some input" />
<a href="">Another Link</a>


You can get to active link with:

// event listener for keyup
function checkTabPress(e) {
    "use strict";
    // pick passed event or global event object if passed one is empty
    e = e || event;
    var activeElement;
    if (e.keyCode == 9) {
        // Here read the active selected link.
        activeElement = document.activeElement;
        // If HTML element is an anchor <a>
        if (activeElement.tagName.toLowerCase() == 'a')
            // get it's hyperlink

var body = document.querySelector('body');
body.addEventListener('keyup', checkTabPress);

Here is working example.

How to not wrap contents of a div?

I don't know the reasoning behind this, but I set my parent container to display:flex and the child containers to display:inline-block and they stayed inline despite the combined width of the children exceeding the parent.

Didn't need to toy with max-width, max-height, white-space, or anything else.

Hope that helps someone.