Programs & Examples On #Document based

Download image from the site in .NET/C#

I have used Fredrik's code above in a project with some slight modifications, thought I'd share:

private static bool DownloadRemoteImageFile(string uri, string fileName)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    HttpWebResponse response;
        response = (HttpWebResponse)request.GetResponse();
    catch (Exception)
        return false;

    // Check that the remote file was found. The ContentType
    // check is performed since a request for a non-existent
    // image file might be redirected to a 404-page, which would
    // yield the StatusCode "OK", even though the image was not
    // found.
    if ((response.StatusCode == HttpStatusCode.OK ||
        response.StatusCode == HttpStatusCode.Moved ||
        response.StatusCode == HttpStatusCode.Redirect) &&
        response.ContentType.StartsWith("image", StringComparison.OrdinalIgnoreCase))

        // if the remote file was found, download it
        using (Stream inputStream = response.GetResponseStream())
        using (Stream outputStream = File.OpenWrite(fileName))
            byte[] buffer = new byte[4096];
            int bytesRead;
                bytesRead = inputStream.Read(buffer, 0, buffer.Length);
                outputStream.Write(buffer, 0, bytesRead);
            } while (bytesRead != 0);
        return true;
        return false;

Main changes are:

  • using a try/catch for the GetResponse() as I was running into an exception when the remote file returned 404
  • returning a boolean

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

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

Check out its already been answered, click here

Ignoring NaNs with str.contains

You can also patern :

DF[DF.col.str.contains(pat = '(foo)', regex = True) ]

How to show empty data message in Datatables

I was finding same but lastly i found an answer. I hope this answer help you so much.

when your array is empty then you can send empty array just like

            echo json_encode($result);
            echo json_encode(array('data'=>''));

Thank you

How to call Oracle MD5 hash function?

I would do:

select DBMS_CRYPTO.HASH(rawtohex('foo') ,2) from dual;



Add data dynamically to an Array

You should use method array_push to add value or array to array exists

$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");

    [0] => orange
    [1] => banana
    [2] => apple
    [3] => raspberry

How to sort an array in descending order in Ruby

For those folks who like to measure speed in IPS ;)

require 'benchmark/ips'

ary = []
1000.times { 
  ary << {:bar => rand(1000)} 

Benchmark.ips do |x|"sort")               { ary.sort{ |a,b| b[:bar] <=> a[:bar] } }"sort reverse")       { ary.sort{ |a,b| a[:bar] <=> b[:bar] }.reverse }"sort_by -a[:bar]")   { ary.sort_by{ |a| -a[:bar] } }"sort_by a[:bar]*-1") { ary.sort_by{ |a| a[:bar]*-1 } }"sort_by.reverse!")   { ary.sort_by{ |a| a[:bar] }.reverse }!

And results:

Warming up --------------------------------------
                sort    93.000  i/100ms
        sort reverse    91.000  i/100ms
    sort_by -a[:bar]   382.000  i/100ms
  sort_by a[:bar]*-1   398.000  i/100ms
    sort_by.reverse!   397.000  i/100ms
Calculating -------------------------------------
                sort    938.530  (± 1.8%) i/s -      4.743k in   5.055290s
        sort reverse    901.157  (± 6.1%) i/s -      4.550k in   5.075351s
    sort_by -a[:bar]      3.814k (± 4.4%) i/s -     19.100k in   5.019260s
  sort_by a[:bar]*-1      3.732k (± 4.3%) i/s -     18.706k in   5.021720s
    sort_by.reverse!      3.928k (± 3.6%) i/s -     19.850k in   5.060202s

    sort_by.reverse!:     3927.8 i/s
    sort_by -a[:bar]:     3813.9 i/s - same-ish: difference falls within error
  sort_by a[:bar]*-1:     3732.3 i/s - same-ish: difference falls within error
                sort:      938.5 i/s - 4.19x  slower
        sort reverse:      901.2 i/s - 4.36x  slower

How to include vars file in a vars file with ansible?

Unfortunately, vars files do not have include statements.

You can either put all the vars into the definitions dictionary, or add the variables as another dictionary in the same file.

If you don't want to have them in the same file, you can include them at the playbook level by adding the vars file at the start of the play:

- hosts: myhosts

    - default_step.yml

or in a task:

- hosts: myhosts

    - name: include default step variables
      include_vars: default_step.yml

Reason: no suitable image found

It occurred on my side when building an app in the command line via xcodebuild and xcrun PackageApplication, signing the app with an enterprise profile. On our CI build servers, the certificate was set to "Always Trust" in the keychain (select certificate -> Get Info -> Trust -> "Use System Default" can be changed to "Always Trust"). I had to set it back to "Use System Default" in order to make this work. Initially we set this to "Always Trust" to work-around the keychain dialogs that appear after software updates and certificate updates.

Why is this rsync connection unexpectedly closed on Windows?

The trick for me was I had ssh conflict.

I have Git installed on my Windows path, which includes ssh. cwrsync also installs ssh.

The trick is to have make a batch file to set the correct paths:


@echo off
SET CWRSYNCHOME=c:\commands\cwrsync
SET HOME=c:\Users\Petah\
%~dp0\cwrsync\bin\rsync.exe %*

On Windows you can type where ssh to check if this is an issue. You will get something like this:

where ssh
C:\Program Files (x86)\Git\bin\ssh.exe
C:\Program Files\cwRsync\ssh.exe

java.lang.ClassNotFoundException: com.sun.jersey.spi.container.servlet.ServletContainer

you need to add jersey-bundle-1.17.1.jar to lib of project

<servlet> <servlet-name>Jersey REST Service</servlet-name> <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class> <!-- <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class> --> <init-param> <param-name></param-name> <!-- <param-name>jersey.config.server.provider.packages</param-name> --> <param-value>package.package.test</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet>

"No Content-Security-Policy meta tag found." error in my phonegap application

For me it was enough to reinstall whitelist plugin:

cordova plugin remove cordova-plugin-whitelist

and then

cordova plugin add cordova-plugin-whitelist

It looks like updating from previous versions of Cordova was not succesful.

Error 1920 service failed to start. Verify that you have sufficient privileges to start system services

I had this issue while testing software. Drivers were not signed.

Tip for me was: in cmd line: (administrator) bcdedit /set TESTSIGNING ON and reboot the machine (shutdown -r -t 5)

Rename a file in C#


public static class FileInfoExtensions
    /// <summary>
    /// Behavior when a new filename exists.
    /// </summary>
    public enum FileExistBehavior
        /// <summary>
        /// None: throw IOException "The destination file already exists."
        /// </summary>
        None = 0,
        /// <summary>
        /// Replace: replace the file in the destination.
        /// </summary>
        Replace = 1,
        /// <summary>
        /// Skip: skip this file.
        /// </summary>
        Skip = 2,
        /// <summary>
        /// Rename: rename the file (like a window behavior)
        /// </summary>
        Rename = 3

    /// <summary>
    /// Rename the file.
    /// </summary>
    /// <param name="fileInfo">the target file.</param>
    /// <param name="newFileName">new filename with extension.</param>
    /// <param name="fileExistBehavior">behavior when new filename is exist.</param>
    public static void Rename(this System.IO.FileInfo fileInfo, string newFileName, FileExistBehavior fileExistBehavior = FileExistBehavior.None)
        string newFileNameWithoutExtension = System.IO.Path.GetFileNameWithoutExtension(newFileName);
        string newFileNameExtension = System.IO.Path.GetExtension(newFileName);
        string newFilePath = System.IO.Path.Combine(fileInfo.Directory.FullName, newFileName);

        if (System.IO.File.Exists(newFilePath))
            switch (fileExistBehavior)
                case FileExistBehavior.None:
                    throw new System.IO.IOException("The destination file already exists.");

                case FileExistBehavior.Replace:

                case FileExistBehavior.Rename:
                    int dupplicate_count = 0;
                    string newFileNameWithDupplicateIndex;
                    string newFilePathWithDupplicateIndex;
                        newFileNameWithDupplicateIndex = newFileNameWithoutExtension + " (" + dupplicate_count + ")" + newFileNameExtension;
                        newFilePathWithDupplicateIndex = System.IO.Path.Combine(fileInfo.Directory.FullName, newFileNameWithDupplicateIndex);
                    while (System.IO.File.Exists(newFilePathWithDupplicateIndex));

                    newFilePath = newFilePathWithDupplicateIndex;

                case FileExistBehavior.Skip:
        System.IO.File.Move(fileInfo.FullName, newFilePath);

How to use this code

class Program
    static void Main(string[] args)
        string targetFile = System.IO.Path.Combine(@"D://test", "New Text Document.txt");
        string newFileName = "Foo.txt";

        // Full pattern
        System.IO.FileInfo fileInfo = new System.IO.FileInfo(targetFile);

        // Or short form
        new System.IO.FileInfo(targetFile).Rename(newFileName);

Autoplay audio files on an iPad with HTML5

Apple does not support the standard completely, but there is a workaround. Their justification is cellular network congestion, maybe because you'll land on pages that play random audio. This behavior doesn't change when a device goes on wifi, maybe for consistency. By the way, those pages are usually a bad idea anyway. You should not be trying to put a soundtrack on every web page. That's just wrong. :)

html5 audio will play if it is started as the result of a user action. Loading a page does not count. So you need to restructure your web app to be an all-in-one-page app. Instead of a link that opens a page that plays audio, you need that link to play it on the current page, without a page change. This "user interaction" rule applies to the html5 methods you can call on an audio or video element. The calls return without any effect if they are fired automatically on page load, but they work when called from event handlers.

git undo all uncommitted or unsaved changes

  • This will unstage all files you might have staged with git add:

    git reset
  • This will revert all local uncommitted changes (should be executed in repo root):

    git checkout .

    You can also revert uncommitted changes only to particular file or directory:

    git checkout [some_dir|file.txt]

    Yet another way to revert all uncommitted changes (longer to type, but works from any subdirectory):

    git reset --hard HEAD
  • This will remove all local untracked files, so only git tracked files remain:

    git clean -fdx

    WARNING: -x will also remove all ignored files, including ones specified by .gitignore! You may want to use -n for preview of files to be deleted.

To sum it up: executing commands below is basically equivalent to fresh git clone from original source (but it does not re-download anything, so is much faster):

git reset
git checkout .
git clean -fdx

Typical usage for this would be in build scripts, when you must make sure that your tree is absolutely clean - does not have any modifications or locally created object files or build artefacts, and you want to make it work very fast and to not re-clone whole repository every single time.

Escape Character in SQL Server

To escape ' you simly need to put another before: ''

As the second answer shows it's possible to escape single quote like this:

select 'it''s escaped'

result will be

it's escaped

If you're concatenating SQL into a VARCHAR to execute (i.e. dynamic SQL), then I'd recommend parameterising the SQL. This has the benefit of helping guard against SQL injection plus means you don't have to worry about escaping quotes like this (which you do by doubling up the quotes).

e.g. instead of doing

SET @SQL = 'SELECT * FROM MyTable WHERE Field1 = ''AAA'''

try this:

SET @SQL = 'SELECT * FROM MyTable WHERE Field1 = @Field1'
EXECUTE sp_executesql @SQL, N'@Field1 VARCHAR(10)', 'AAA'

Check whether a value exists in JSON object

iterate through the array and check its name value.

Converting an integer to binary in C

void intToBin(int digit) {
    int b;
    int k = 0;
    char *bits;

    bits= (char *) malloc(sizeof(char));
    while (digit) {
        b = digit % 2;
        digit = digit / 2;
        bits[k] = b;

        printf("%d", b);
    for (int i = k - 1; i >= 0; i--) {
        printf("%d", bits[i]);



Write Array to Excel Range

Thanks for the pointers guys - the Value vs Value2 argument got me a different set of search results which helped me realise what the answer is. Incidentally, the Value property is a parametrized property, which must be accessed through an accessor in C#. These are called get_Value and set_Value, and take an optional enum value. If anyone's interested, this explains it nicely.

It's possible to make the assignment via the Value2 property however, which is preferable as the interop documentation recommends against the use use of the get_Value and set_Value methods, for reasons beyond my understanding.

The key seems to be the dimension of the array of objects. For the call to work the array must be declared as two-dimensional, even if you're only assigning one-dimensional data.

I declared my data array as an object[NumberofRows,1] and the assignment call worked.

Caching a jquery ajax response in javascript/browser

cache:true only works with GET and HEAD request.

You could roll your own solution as you said with something along these lines :

var localCache = {
    data: {},
    remove: function (url) {
    exist: function (url) {
        return &&[url] !== null;
    get: function (url) {
        console.log('Getting in cache for url' + url);
    set: function (url, cachedData, callback) {
        localCache.remove(url);[url] = cachedData;
        if ($.isFunction(callback)) callback(cachedData);

$(function () {
    var url = '/echo/jsonp/';
    $('#ajaxButton').click(function (e) {
            url: url,
            data: {
                test: 'value'
            cache: true,
            beforeSend: function () {
                if (localCache.exist(url)) {
                    return false;
                return true;
            complete: function (jqXHR, textStatus) {
                localCache.set(url, jqXHR, doSomething);

function doSomething(data) {

Working fiddle here

EDIT: as this post becomes popular, here is an even better answer for those who want to manage timeout cache and you also don't have to bother with all the mess in the $.ajax() as I use $.ajaxPrefilter(). Now just setting {cache: true} is enough to handle the cache correctly :

var localCache = {
     * timeout for cache in millis
     * @type {number}
    timeout: 30000,
     * @type {{_: number, data: {}}}
    data: {},
    remove: function (url) {
    exist: function (url) {
        return !![url] && ((new Date().getTime() -[url]._) < localCache.timeout);
    get: function (url) {
        console.log('Getting in cache for url' + url);
    set: function (url, cachedData, callback) {
        localCache.remove(url);[url] = {
            _: new Date().getTime(),
            data: cachedData
        if ($.isFunction(callback)) callback(cachedData);

$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
    if (options.cache) {
        var complete = originalOptions.complete || $.noop,
            url = originalOptions.url;
        //remove jQuery cache as we have our own localCache
        options.cache = false;
        options.beforeSend = function () {
            if (localCache.exist(url)) {
                return false;
            return true;
        options.complete = function (data, textStatus) {
            localCache.set(url, data, complete);

$(function () {
    var url = '/echo/jsonp/';
    $('#ajaxButton').click(function (e) {
            url: url,
            data: {
                test: 'value'
            cache: true,
            complete: doSomething

function doSomething(data) {

And the fiddle here CAREFUL, not working with $.Deferred

Here is a working but flawed implementation working with deferred:

var localCache = {
     * timeout for cache in millis
     * @type {number}
    timeout: 30000,
     * @type {{_: number, data: {}}}
    data: {},
    remove: function (url) {
    exist: function (url) {
        return !![url] && ((new Date().getTime() -[url]._) < localCache.timeout);
    get: function (url) {
        console.log('Getting in cache for url' + url);
    set: function (url, cachedData, callback) {
        localCache.remove(url);[url] = {
            _: new Date().getTime(),
            data: cachedData
        if ($.isFunction(callback)) callback(cachedData);

$.ajaxPrefilter(function (options, originalOptions, jqXHR) {
    if (options.cache) {
        //Here is our identifier for the cache. Maybe have a better, safer ID (it depends on the object string representation here) ?
        // on $.ajax call we could also set an ID in originalOptions
        var id = originalOptions.url+ JSON.stringify(;
        options.cache = false;
        options.beforeSend = function () {
            if (!localCache.exist(id)) {
                jqXHR.promise().done(function (data, textStatus) {
                    localCache.set(id, data);
            return true;


$.ajaxTransport("+*", function (options, originalOptions, jqXHR, headers, completeCallback) {

    //same here, careful because options.url has already been through jQuery processing
    var id = originalOptions.url+ JSON.stringify(;

    options.cache = false;

    if (localCache.exist(id)) {
        return {
            send: function (headers, completeCallback) {
                completeCallback(200, "OK", localCache.get(id));
            abort: function () {
                /* abort code, nothing needed here I guess... */

$(function () {
    var url = '/echo/jsonp/';
    $('#ajaxButton').click(function (e) {
            url: url,
            data: {
                test: 'value'
            cache: true
        }).done(function (data, status, jq) {
                data: data,
                status: status,
                jqXHR: jq

Fiddle HERE Some issues, our cache ID is dependent of the json2 lib JSON object representation.

Use Console view (F12) or FireBug to view some logs generated by the cache.

Repair all tables in one go

There is no default command to do that, but you may create a procedure to do the job. It will iterate through rows of information_schema and call REPAIR TABLE 'tablename'; for every row. CHECK TABLE is not yet supported for prepared statements. Here's the example (replace MYDATABASE with your database name):

CREATE DEFINER = 'root'@'localhost'
  DECLARE tableName char(100);

  OPEN rCursor;
  FETCH rCursor INTO tableName;

  WHILE endloop = 0 DO
    SET @sql = CONCAT("REPAIR TABLE `", tableName, "`");
    PREPARE statement FROM @sql;
    EXECUTE statement;

    FETCH rCursor INTO tableName;

  CLOSE rCursor;

$(this).serialize() -- How to add a value?

Add the item first and then serialize:

    type: 'POST',
    url: this.action,
    data: $.extend($(this), {'NonFormValue': NonFormValue}).serialize()

How to execute multiple SQL statements from java

you can achieve that using Following example uses addBatch & executeBatch commands to execute multiple SQL commands simultaneously.

Batch Processing allows you to group related SQL statements into a batch and submit them with one call to the database. reference

When you send several SQL statements to the database at once, you reduce the amount of communication overhead, thereby improving performance.

  • JDBC drivers are not required to support this feature. You should use the DatabaseMetaData.supportsBatchUpdates() method to determine if the target database supports batch update processing. The method returns true if your JDBC driver supports this feature.
  • The addBatch() method of Statement, PreparedStatement, and CallableStatement is used to add individual statements to the batch. The executeBatch() is used to start the execution of all the statements grouped together.
  • The executeBatch() returns an array of integers, and each element of the array represents the update count for the respective update statement.
  • Just as you can add statements to a batch for processing, you can remove them with the clearBatch() method. This method removes all the statements you added with the addBatch() method. However, you cannot selectively choose which statement to remove.


import java.sql.*;

public class jdbcConn {
   public static void main(String[] args) throws Exception{
      Connection con = DriverManager.getConnection

      Statement stmt = con.createStatement
      String insertEmp1 = "insert into emp values
      String insertEmp2 = "insert into emp values
      String insertEmp3 = "insert into emp values
      stmt.addBatch(insertEmp1);//inserting Query in stmt
      ResultSet rs = stmt.executeQuery("select * from emp");
      System.out.println("rows before batch execution= "
      + rs.getRow());
      System.out.println("Batch executed");
      rs = stmt.executeQuery("select * from emp");
      System.out.println("rows after batch execution= "
      + rs.getRow());


How to convert an integer to a string in any base?

Here is an example of how to convert a number of any base to another base.

from collections import namedtuple

Test = namedtuple("Test", ["n", "from_base", "to_base", "expected"])

def convert(n: int, from_base: int, to_base: int) -> int:
    digits = []
    while n:
        (n, r) = divmod(n, to_base)
    return sum(from_base ** i * v for i, v in enumerate(digits))

if __name__ == "__main__":
    tests = [
        Test(32, 16, 10, 50),
        Test(32, 20, 10, 62),
        Test(1010, 2, 10, 10),
        Test(8, 10, 8, 10),
        Test(150, 100, 1000, 150),
        Test(1500, 100, 10, 1050000),

    for test in tests:
        result = convert(*test[:-1])
        assert result == test.expected, f"{test=}, {result=}"

Using PI in python 2.7

To have access to stuff provided by math module, like pi. You need to import the module first:

import math
print (math.pi)

Swipe to Delete and the "More" button (like in Mail app on iOS 7)

I hope you cant wait till apple gives you what ever you need right? So here is my option.

Create a custom cell. Have two uiviews in it

1. upper
2. lower

In lower view, add what ever buttons you need. Deal its actions just like any other IBActions. you can decide the animation time, style and anything.

now add a uiswipegesture to the upper view and reveal your lower view on swipe gesture. I have done this before and its the simplest option as far as I am concerned.

Hope that help.

How can I use Ruby to colorize the text output to a terminal?

As String class methods (unix only):

class String
def black;          "\e[30m#{self}\e[0m" end
def red;            "\e[31m#{self}\e[0m" end
def green;          "\e[32m#{self}\e[0m" end
def brown;          "\e[33m#{self}\e[0m" end
def blue;           "\e[34m#{self}\e[0m" end
def magenta;        "\e[35m#{self}\e[0m" end
def cyan;           "\e[36m#{self}\e[0m" end
def gray;           "\e[37m#{self}\e[0m" end

def bg_black;       "\e[40m#{self}\e[0m" end
def bg_red;         "\e[41m#{self}\e[0m" end
def bg_green;       "\e[42m#{self}\e[0m" end
def bg_brown;       "\e[43m#{self}\e[0m" end
def bg_blue;        "\e[44m#{self}\e[0m" end
def bg_magenta;     "\e[45m#{self}\e[0m" end
def bg_cyan;        "\e[46m#{self}\e[0m" end
def bg_gray;        "\e[47m#{self}\e[0m" end

def bold;           "\e[1m#{self}\e[22m" end
def italic;         "\e[3m#{self}\e[23m" end
def underline;      "\e[4m#{self}\e[24m" end
def blink;          "\e[5m#{self}\e[25m" end
def reverse_color;  "\e[7m#{self}\e[27m" end

and usage:

puts "I'm back green".bg_green
puts "I'm red and back cyan".red.bg_cyan
puts "I'm bold and green and backround red"

on my console:

enter image description here


def no_colors
  self.gsub /\e\[\d+m/, ""

removes formatting characters


puts "\e[31m" # set format (red foreground)
puts "\e[0m"   # clear format
puts "green-#{"red".red}-green".green # will be green-red-normal, because of \e[0

Returning a promise in an async function in TypeScript

When you do new Promise((resolve)... the type inferred was Promise<{}> because you should have used new Promise<number>((resolve).

It is interesting that this issue was only highlighted when the async keyword was added. I would recommend reporting this issue to the TS team on GitHub.

There are many ways you can get around this issue. All the following functions have the same behavior:

const whatever1 = () => {
    return new Promise<number>((resolve) => {

const whatever2 = async () => {
    return new Promise<number>((resolve) => {

const whatever3 = async () => {
    return await new Promise<number>((resolve) => {

const whatever4 = async () => {
    return Promise.resolve(4);

const whatever5 = async () => {
    return await Promise.resolve(4);

const whatever6 = async () => Promise.resolve(4);

const whatever7 = async () => await Promise.resolve(4);

In your IDE you will be able to see that the inferred type for all these functions is () => Promise<number>.

Syntax for if/else condition in SCSS mixin

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

@mixin clearfix($width: null) {

  @if not ($width) {

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

  } @else {

    display: inline-block;
    width: $width;


nginx upload client_max_body_size issue

From the documentation:

It is necessary to keep in mind that the browsers do not know how to correctly show this error.

I suspect this is what's happening, if you inspect the HTTP to-and-fro using tools such as Firebug or Live HTTP Headers (both Firefox extensions) you'll be able to see what's really going on.

Jquery AJAX: No 'Access-Control-Allow-Origin' header is present on the requested resource

If the requested resource of the server is using Flask. Install Flask-CORS.

How to see data from .RData file?

If you have a lot of variables in your Rdata file and don't want them to clutter your global environment, create a new environment and load all of the data to this new environment.

load(file.path("C:/Users/isfar.RData"), isfar_env <- new.env() )

# Access individual variables in the RData file using '$' operator

# List all of the variable names in RData:

WordPress - Check if user is logged in

This problem is from the lazy update data request of Chrome. At the first time you go to homepage. Chrome request with empty data. Then you go to the login page and logged in. When you back home page Chrome lazy to update the cookie data request because this domain is the same with the first time you access. Solution: Add parameter for home url. That helps Chrome realizes that this request need to update cookie to call to the server.

add at dashboard page

$track = '?track='.uniqid();
<a href="<?= get_home_url(). $track ?>"> <img src="/img/logo.svg"></a>

Fit website background image to screen size

You can try with

.appBackground {
    position: relative;
    background-image: url(".../img/background.jpg");
    background-size:100% 100vh;

works for me :)

adding 30 minutes to datetime php/mysql

If you are using MySQL you can do it like this:

SELECT '2008-12-31 23:59:59' + INTERVAL 30 MINUTE;

For a pure PHP solution use strtotime

strtotime('+ 30 minute',$yourdate);

What is the @Html.DisplayFor syntax for?

After looking for an answer for myself for some time, i could find something. in general if we are using it for just one property it appears same even if we do a "View Source" of generated HTML Below is generated HTML for example, when i want to display only Name property for my class

    myClassNameProperty, This is direct from Item

This is the generated HTML from below code


@item.Genre.Name, This is direct from Item

At the same time now if i want to display all properties in one statement for my class "Genre" in this case, i can use @Html.DisplayFor() to save on my typing, for least

i can write @Html.DisplayFor(modelItem=>item.Genre) in place of writing a separate statement for each property of Genre as below


and so on depending on number of properties.

How to get response as String using retrofit without using GSON or any other library in android

** Update ** A scalars converter has been added to retrofit that allows for a String response with less ceremony than my original answer below.

Example interface --

public interface GitHubService {
    Call<String> listRepos(@Path("user") String user);

Add the ScalarsConverterFactory to your retrofit builder. Note: If using ScalarsConverterFactory and another factory, add the scalars factory first.

Retrofit retrofit = new Retrofit.Builder()
    // add other factories here, if needed.

You will also need to include the scalars converter in your gradle file --

implementation 'com.squareup.retrofit2:converter-scalars:2.1.0'

--- Original Answer (still works, just more code) ---

I agree with @CommonsWare that it seems a bit odd that you want to intercept the request to process the JSON yourself. Most of the time the POJO has all the data you need, so no need to mess around in JSONObject land. I suspect your specific problem might be better solved using a custom gson TypeAdapter or a retrofit Converter if you need to manipulate the JSON. However, retrofit provides more the just JSON parsing via Gson. It also manages a lot of the other tedious tasks involved in REST requests. Just because you don't want to use one of the features, doesn't mean you have to throw the whole thing out. There are times you just want to get the raw stream, so here is how to do it -

First, if you are using Retrofit 2, you should start using the Call API. Instead of sending an object to convert as the type parameter, use ResponseBody from okhttp --

public interface GitHubService {
    Call<ResponseBody> listRepos(@Path("user") String user);

then you can create and execute your call --

GitHubService service = retrofit.create(GitHubService.class);
Call<ResponseBody> result = service.listRepos(username);
result.enqueue(new Callback<ResponseBody>() {
    public void onResponse(Response<ResponseBody> response) {
        try {
        } catch (IOException e) {

    public void onFailure(Throwable t) {

Note The code above calls string() on the response object, which reads the entire response into a String. If you are passing the body off to something that can ingest streams, you can call charStream() instead. See the ResponseBody docs.

ffmpeg usage to encode a video to H264 codec format

I used these options to convert to the H.264/AAC .mp4 format for HTML5 playback (I think it may help other guys with this problem in some way):

ffmpeg -i input.flv -vcodec mpeg4 -acodec aac output.mp4


As @LordNeckbeard mentioned, the previous line will produce MPEG-4 Part 2 (back in 2012 that worked somehow, I don't remember/understand why). Use the libx264 encoder to produce the proper video with H.264/AAC. To test the output file you can just drag it to a browser window and it should playback just fine.

ffmpeg -i input.flv -vcodec libx264 -acodec aac output.mp4

How to pass arguments to entrypoint in docker-compose.yml

Whatever is specified in the command in docker-compose.yml should get appended to the entrypoint defined in the Dockerfile, provided entrypoint is defined in exec form in the Dockerfile.

If the EntryPoint is defined in shell form, then any CMD arguments will be ignored.

Copy data into another table

Simple way if new table does not exist and you want to make a copy of old table with everything then following works in SQL Server.

SELECT * INTO NewTable FROM OldTable

Not unique table/alias

 select persons.personsid,name,,address
    -> from persons
    -> inner join persons on info.infoid =;

Does VBA contain a comment block syntax?

Although there isn't a syntax, you can still get close by using the built-in block comment buttons:

If you're not viewing the Edit toolbar already, right-click on the toolbar and enable the Edit toolbar:

enter image description here

Then, select a block of code and hit the "Comment Block" button; or if it's already commented out, use the "Uncomment Block" button:

enter image description here

Fast and easy!

Python Git Module experiences?

PTBNL's Answer is quite perfect for me. I make a little more for Windows user.

import time
import subprocess
def gitAdd(fileName, repoDir):
    cmd = 'git add ' + fileName
    pipe = subprocess.Popen(cmd, shell=True, cwd=repoDir,stdout = subprocess.PIPE,stderr = subprocess.PIPE )
    (out, error) = pipe.communicate()
    print out,error

def gitCommit(commitMessage, repoDir):
    cmd = 'git commit -am "%s"'%commitMessage
    pipe = subprocess.Popen(cmd, shell=True, cwd=repoDir,stdout = subprocess.PIPE,stderr = subprocess.PIPE )
    (out, error) = pipe.communicate()
    print out,error
def gitPush(repoDir):
    cmd = 'git push '
    pipe = subprocess.Popen(cmd, shell=True, cwd=repoDir,stdout = subprocess.PIPE,stderr = subprocess.PIPE )
    (out, error) = pipe.communicate()

uploaddate= str(temp[0])+'_'+str(temp[1])+'_'+str(temp[2])+'_'+str(temp[3])+'_'+str(temp[4])

repoDir='d:\\c_Billy\\vfat\\Programming\\Projector\\billyccm' # your git repository , windows your need to use double backslash for right directory.
gitAdd('.',repoDir )
gitCommit(uploaddate, repoDir)

MySQL combine two columns into one column

My guess is that you are using MySQL where the + operator does addition, along with silent conversion of the values to numbers. If a value does not start with a digit, then the converted value is 0.

So try this:

select concat(column1, column2)

Two ways to add a space:

select concat(column1, ' ', column2)
select concat_ws(' ', column1, column2)

How to set 777 permission on a particular folder?

go to FileZilla and select which folder you will be give 777 permission, then right click set permission 777 and select check box, then ok.

size of struct in C

Your default alignment is probably 4 bytes. Either the 30 byte element got 32, or the structure as a whole was rounded up to the next 4 byte interval.

How to use Ajax.ActionLink?

@Ajax.ActionLink requires jQuery AJAX Unobtrusive library. You can download it via nuget:

Install-Package Microsoft.jQuery.Unobtrusive.Ajax

Then add this code to your View:


Git says remote ref does not exist when I delete remote branch

  1. get the list of remote branches
git fetch # synchronize with the server
git branch --remote # list remote branches
  1. you should get a list of the remote branches:
origin/HEAD -> origin/master
  1. now, we can delete the branch:
git push origin --delete deleteme

JFrame.dispose() vs System.exit()

In addition to the above you can use the System.exit() to return an exit code which may be very usuefull specially if your calling the process automatically using the System.exit(code); this can help you determine for example if an error has occured during the run.

How do I retrieve my MySQL username and password?

An improvement to the most useful answer here:

1] No need to restart the mysql server
2] Security concern for a MySQL server connected to a network

There is no need to restart the MySQL server.

use FLUSH PRIVILEGES; after the update mysql.user statement for password change.

The FLUSH statement tells the server to reload the grant tables into memory so that it notices the password change.

The --skip-grant-options enables anyone to connect without a password and with all privileges. Because this is insecure, you might want to

use --skip-grant-tables in conjunction with --skip-networking to prevent remote clients from connecting.

from: reference: resetting-permissions-generic

How to change the port of Tomcat from 8080 to 80?

On Ubuntu and Debian systems, there are several steps needed:

  1. In server.xml, change the line <Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443"/> to have port="80".

  2. Install the recommended (not required) authbind package, with a command like:

    sudo apt-get install authbind

  3. Enable authbind in the server.xml file (in either /etc/tomcat6 or /etc/tomcat7) by uncommenting and setting the line like:


All three steps are needed.

jQuery get content between <div> tags

Give the div a class or id and do something like this:


That works at the DOM level.

Can you have multiple $(document).ready(function(){ ... }); sections?

You can also do it the following way:

<script src=""></script>

<h2>This is a test of jQuery!</h2>
<p id="test">This is a hidden paragraph.</p>
<button id="hide">Click me to hide</button>
<button id="show">Click me to show</button>

the previous answers showed using multiple named functions inside a single .ready block, or a single unnamed function in the .ready block, with another named function outside the .ready block. I found this question while researching if there was a way to have multiple unnamed functions inside the .ready block - I could not get the syntax correct. I finally figured it out, and hoped that by posting my test code I would help others looking for the answer to the same question I had

HTML5 Video // Completely Hide Controls

<video width="320" height="240" autoplay="autoplay">
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
  Your browser does not support the video tag.

How do you specify the Java compiler version in a pom.xml file?

        <version>(whatever version is current)</version>
          <!-- or whatever version you use -->

See the config page for the maven compiler plugin:

Oh, and: don't use Java 1.3.x, current versions are Java 1.7.x or 1.8.x

What does "subject" mean in certificate?

The subject of the certificate is the entity its public key is associated with (i.e. the "owner" of the certificate).

As RFC 5280 says:

The subject field identifies the entity associated with the public key stored in the subject public key field. The subject name MAY be carried in the subject field and/or the subjectAltName extension.

X.509 certificates have a Subject (Distinguished Name) field and can also have multiple names in the Subject Alternative Name extension.

The Subject DN is made of multiple relative distinguished names (RDNs) (themselves made of attribute assertion values) such as "CN=yourname" or "O=yourorganization".

In the context of the article you're linking to, the subject would be the user/owner of the cert.

Converting a list to a set changes element order

Answering your first question, a set is a data structure optimized for set operations. Like a mathematical set, it does not enforce or maintain any particular order of the elements. The abstract concept of a set does not enforce order, so the implementation is not required to. When you create a set from a list, Python has the liberty to change the order of the elements for the needs of the internal implementation it uses for a set, which is able to perform set operations efficiently.

Entity Framework select distinct name

In order to avoid ORDER BY items must appear in the select list if SELECT DISTINCT error, the best should be

var results = (
    from ta in DBContext.TestAddresses
    select ta.Name
.OrderBy( x => 1);

How to check if a value exists in an array in Ruby

['Cat', 'Dog', 'Bird'].detect { |x| x == 'Dog'}
=> "Dog"
!['Cat', 'Dog', 'Bird'].detect { |x| x == 'Dog'}.nil?
=> true

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

It seems the original author has found their solution, but for anyone else who gets here looking to add actual custom headers, if you have access to mod the generated Protocol code you can override GetWebRequest:

protected override System.Net.WebRequest GetWebRequest(Uri uri)
  System.Net.WebRequest request = base.GetWebRequest(uri);
  request.Headers.Add("myheader", "myheader_value");
  return request;

Make sure you remove the DebuggerStepThroughAttribute attribute if you want to step into it.

How can I calculate the number of lines changed between two commits in Git?

I just solved this problem for myself, so I'll share what I came up with. Here's the end result:

> git summary --since=yesterday
total: 114 file changes, 13800 insertions(+) 638 deletions(-)

The underlying command looks like this:

git log --numstat --format="" "$@" | awk '{files += 1}{ins += $1}{del += $2} END{print "total: "files" files, "ins" insertions(+) "del" deletions(-)"}'

Note the $@ in the log command to pass on your arguments such as --author="Brian" or --since=yesterday.

Escaping the awk to put it into a git alias was messy, so instead, I put it into an executable script on my path (~/bin/git-stat-sum), then used the script in the alias in my .gitconfig:

    summary = !git-stat-sum \"$@\"

And it works really well. One last thing to note is that file changes is the number of changes to files, not the number of unique files changed. That's what I was looking for, but it may not be what you expect.

Here's another example or two

git summary --author=brian
git summary
# combine them as you like
git summary --author=brian
git summary --all

Really, you should be able to replace any git log command with git summary.

How to set a DateTime variable in SQL Server 2008?

First of all - use single quotes around your date literals!

Second of all, I would strongly recommend always using the ISO-8601 date format - this works regardless of what your locale, regional or language settings are on your SQL Server.

The ISO-8601 format is either:

  • YYYYMMDD for dates only (e.g. 20110825 for the 25th of August, 2011)
  • YYYY-MM-DDTHH:MM:SS for dates and time (e.g. 2011-08-25T14:15:00 for 25th of AUgust, 14:15/2:15pm in the afternoon)

unary operator expected in shell script when comparing null value with string

Why all people want to use '==' instead of simple '=' ? It is bad habit! It used only in [[ ]] expression. And in (( )) too. But you may use just = too! It work well in any case. If you use numbers, not strings use not parcing to strings and then compare like strings but compare numbers. like that

let -i i=5 # garantee that i is nubmber
test $i -eq 5 && echo "$i is equal 5" || echo "$i not equal 5"

It's match better and quicker. I'm expert in C/C++, Java, JavaScript. But if I use bash i never use '==' instead '='. Why you do so?

time.sleep -- sleeps thread or process?

The thread will block, but the process is still alive.

In a single threaded application, this means everything is blocked while you sleep. In a multithreaded application, only the thread you explicitly 'sleep' will block and the other threads still run within the process.

Get source jar files attached to Eclipse for Maven-managed dependencies

I had a similar problem, and the solution that worked best for me was to include the source in the same jar as the compiled code (so a given directory in the jar would include both and Foo.class). Eclipse automatically associates the source with the compiled code, and automatically provides the JavaDoc from the source. Obviously, that's only helpful if you control the artifact.

How to open Atom editor from command line in OS X?

With conemu on windows 10 I couldn't call atom from console even after I added %USERPROFILE%\AppData\Local\atom\bin to PATH in environment variables. I just added

alias atom="C:/Users/me/AppData/local/atom/app-1.12.7/atom"

to my .bashrc file.

conflicting types error when compiling c program using gcc

If you don't declare a function and it only appears after being called, it is automatically assumed to be int, so in your case, you didn't declare

void my_print (char *);
void my_print2 (char *);

before you call it in main, so the compiler assume there are functions which their prototypes are int my_print2 (char *); and int my_print2 (char *); and you can't have two functions with the same prototype except of the return type, so you get the error of conflicting types.

As Brian suggested, declare those two methods before main.

Difference Between ViewResult() and ActionResult()

ActionResult is an abstract class that can have several subtypes.

ActionResult Subtypes

  • ViewResult - Renders a specifed view to the response stream

  • PartialViewResult - Renders a specifed partial view to the response stream

  • EmptyResult - An empty response is returned

  • RedirectResult - Performs an HTTP redirection to a specifed URL

  • RedirectToRouteResult - Performs an HTTP redirection to a URL that is determined by the routing engine, based on given route data

  • JsonResult - Serializes a given ViewData object to JSON format

  • JavaScriptResult - Returns a piece of JavaScript code that can be executed on the client

  • ContentResult - Writes content to the response stream without requiring a view

  • FileContentResult - Returns a file to the client

  • FileStreamResult - Returns a file to the client, which is provided by a Stream

  • FilePathResult - Returns a file to the client


How to fill Matrix with zeros in OpenCV?

You can choose filling zero data or create zero Mat.

  1. Filling zero data with setTo():

  2. Create zero data with zeros():

    img = zeros(img.size(), img.type());

The img changes address of memory.

How to get the size of a file in MB (Megabytes)?

Example :

public static String getStringSizeLengthFile(long size) {

    DecimalFormat df = new DecimalFormat("0.00");

    float sizeKb = 1024.0f;
    float sizeMb = sizeKb * sizeKb;
    float sizeGb = sizeMb * sizeKb;
    float sizeTerra = sizeGb * sizeKb;

    if(size < sizeMb)
        return df.format(size / sizeKb)+ " Kb";
    else if(size < sizeGb)
        return df.format(size / sizeMb) + " Mb";
    else if(size < sizeTerra)
        return df.format(size / sizeGb) + " Gb";

    return "";

Self Join to get employee manager name

create table abc(emp_ID int, manager varchar(20) , manager_id int)

emp_ID  manager manager_id
1       abc     NULL
2       def     1
3       ghi     2
4       klm     3
5       def1    1
6       ghi1    2
7       klm1    3

select a.emp_ID , a.manager emp_name,b.manager manager_name
from abc a
left join abc b
on a.manager_id = b.emp_ID

emp_ID  emp_name  manager_name
1       abc       NULL
2       def       abc
3       ghi       def
4       klm       ghi
5       def1      abc
6       ghi1      def
7       klm1      ghi

Django auto_now and auto_now_add

I think the easiest (and maybe most elegant) solution here is to leverage the fact that you can set default to a callable. So, to get around admin's special handling of auto_now, you can just declare the field like so:

from django.utils import timezone
date_field = models.DateField(

It's important that you don't use as the default value wouldn't update (i.e., default gets set only when the code is loaded). If you find yourself doing this a lot, you could create a custom field. However, this is pretty DRY already I think.

Cannot install Aptana Studio 3.6 on Windows

You have to use portable git not installer.Extract the folder to Program Files and rename the folder name from PortableGit to Git.

How to do the Recursive SELECT query in MySQL?

leftclickben answer worked for me, but I wanted a path from a given node back up the tree to the root, and these seemed to be going the other way, down the tree. So, I had to flip some of the fields around and renamed for clarity, and this works for me, in case this is what anyone else wants too--

item | parent
1    | null
2    | 1
3    | 1
4    | 2
5    | 4
6    | 3


select t.item_id as item, @pv:=t.parent as parent
from (select * from item_tree order by item_id desc) t
(select @pv:=6)tmp
where t.item_id=@pv;


item | parent
6    | 3
3    | 1
1    | null

Invoking a static method using reflection

String methodName= "...";
String[] args = {};

Method[] methods = clazz.getMethods();
for (Method m : methods) {
    if (methodName.equals(m.getName())) {
        // for static methods we can use null as instance of class
        m.invoke(null, new Object[] {args});

Python return statement error " 'return' outside function"

Use quit() in this context. break expects to be inside a loop, and return expects to be inside a function.

How do I check if a variable exists?

Like so:

def no(var):
    "give var as a string (quote it like 'var')"
    assert(var not in vars())
    assert(var not in globals())
    assert(var not in vars(__builtins__))
    import keyword
    assert(var not in keyword.kwlist)

Then later:

foo = ....

If your new variable foo is not safe to use, you'll get an AssertionError exception which will point to the line that failed, and then you will know better. Here is the obvious contrived self-reference:


AssertionError                            Traceback (most recent call last)
<ipython-input-88-d14ecc6b025a> in <module>
----> 1 no('no')

<ipython-input-86-888a9df72be0> in no(var)
      2     "give var as a string (quote it)"
      3     assert( var not in vars())
----> 4     assert( var not in globals())
      5     assert( var not in vars(__builtins__))
      6     import keyword


HTML5 Local storage vs. Session storage

localStorage and sessionStorage both extend Storage. There is no difference between them except for the intended "non-persistence" of sessionStorage.

That is, the data stored in localStorage persists until explicitly deleted. Changes made are saved and available for all current and future visits to the site.

For sessionStorage, changes are only available per tab. Changes made are saved and available for the current page in that tab until it is closed. Once it is closed, the stored data is deleted.

What is the proper way to re-attach detached objects in Hibernate?

If you are sure that your entity has not been modified (or if you agree any modification will be lost), then you may reattach it to the session with lock.

session.lock(entity, LockMode.NONE);

It will lock nothing, but it will get the entity from the session cache or (if not found there) read it from the DB.

It's very useful to prevent LazyInitException when you are navigating relations from an "old" (from the HttpSession for example) entities. You first "re-attach" the entity.

Using get may also work, except when you get inheritance mapped (which will already throw an exception on the getId()).

entity = session.get(entity.getClass(), entity.getId());

What is "overhead"?

You could use a dictionary. The definition is the same. But to save you time, Overhead is work required to do the productive work. For instance, an algorithm runs and does useful work, but requires memory to do its work. This memory allocation takes time, and is not directly related to the work being done, therefore is overhead.


The problem with all presented answers it complete lack of taking triggers (and probably other side effects) into account. Solution like


leads to both triggers executed (for insert and then for update) when row does not exist.

Proper solution is


in that case only one statement is executed (when row exists or not).

How to export data with Oracle SQL Developer?

In version 3, they changed "export" to "unload". It still functions more or less the same.

How to get the latest record in each group using GROUP BY?

This is a standard problem.

Note that MySQL allows you to omit columns from the GROUP BY clause, which Standard SQL does not, but you do not get deterministic results in general when you use the MySQL facility.

  FROM Messages AS M
  JOIN (SELECT To_ID, From_ID, MAX(TimeStamp) AS Most_Recent
          FROM Messages
         WHERE To_ID = 12345678
         GROUP BY From_ID
       ) AS R
    ON R.To_ID = M.To_ID AND R.From_ID = M.From_ID AND R.Most_Recent = M.TimeStamp
 WHERE M.To_ID = 12345678

I've added a filter on the To_ID to match what you're likely to have. The query will work without it, but will return a lot more data in general. The condition should not need to be stated in both the nested query and the outer query (the optimizer should push the condition down automatically), but it can do no harm to repeat the condition as shown.

WordPress query single post by slug

As wordpress api has changed, you can´t use get_posts with param 'post_name'. I´ve modified Maartens function a bit:

function get_post_id_by_slug( $slug, $post_type = "post" ) {
    $query = new WP_Query(
            'name'   => $slug,
            'post_type'   => $post_type,
            'numberposts' => 1,
            'fields'      => 'ids',
        ) );
    $posts = $query->get_posts();
    return array_shift( $posts );
} cannot identify image file - Python?

For me it was fixed by downloading the image data set I was using again (in fact I forwarded the copy I had locally using vs-code's SFTP). Here is the jupyter notebook I used (in vscode) with it's output:

from pathlib import Path

import PIL
import PIL.Image as PILI
#from PIL import Image


img_path = Path('PATH_UR_DATASET/miniImagenet/train/n03998194/n0399819400000585.jpg')
img ='RGB')



<PIL.Image.Image image mode=RGB size=158x160 at 0x7F4AD0A1E050>

note that open always opens in r mode and even has a check to throw an error if that mode is changed.

Toggle display:none style with JavaScript

you can do this easily by using jquery using .css property... try this one:

document.all vs. document.getElementById

document.all is a proprietary Microsoft extension to the W3C standard.

getElementById() is standard - use that.

However, consider if using a js library like jQuery would come in handy. For example, $("#id") is the jQuery equivalent for getElementById(). Plus, you can use more than just CSS3 selectors.

How to delete Certain Characters in a excel 2010 cell

If [John Smith] is in cell A1, then use this formula to do what you want:

=SUBSTITUTE(SUBSTITUTE(A1, "[", ""), "]", "")

The inner SUBSTITUTE replaces all instances of "[" with "" and returns a new string, then the other SUBSTITUTE replaces all instances of "]" with "" and returns the final result.

jquery fill dropdown with json data

If your data is already in array form, it's really simple using jQuery:


     //this refers to the current item being iterated over

     var option = $('<option />');
     option.attr('value', this.value).text(this.label);


.ajax() is more flexible than .getJSON() - for one, getJson is targeted specifically as a GET request to retrieve json; ajax() can request on any verb to get back any content type (although sometimes that's not useful). getJSON internally calls .ajax().

ASP.Net MVC Redirect To A Different View

 if (true)
   return View();
   return View("another view name");

JSON serialization/deserialization in ASP.Net Core

.net core

using System.Text.Json;

To serialize

var jsonStr = JsonSerializer.Serialize(MyObject)


var weatherForecast = JsonSerializer.Deserialize<MyObject>(jsonStr);

For more information about excluding properties and nulls check out This Microsoft side

Using scanner.nextLine()

It's because when you enter a number then press Enter, input.nextInt() consumes only the number, not the "end of line". Primitive data types like int, double etc do not consume "end of line", therefore the "end of line" remains in buffer and When executes, it consumes the "end of line" from buffer from the first input. That's why, your String sentence = only consumes the "end of line" and does not wait to read from keyboard.

Tip: use scanner.nextLine() instead of because does not read white spaces from the keyboard. (Truncate the string after giving some space from keyboard, only show string before space.)

How do I check the operating system in Python?

You can get a pretty coarse idea of the OS you're using by checking sys.platform.

Once you have that information you can use it to determine if calling something like os.uname() is appropriate to gather more specific information. You could also use something like Python System Information on unix-like OSes, or pywin32 for Windows.

There's also psutil if you want to do more in-depth inspection without wanting to care about the OS.

PHP: How to get referrer URL?

Underscore. Not space.


How to get base URL in Web API controller?

In .NET Core WebAPI (version 3.0 and above):

var requestUrl = $"{Request.Scheme}://{Request.Host.Value}/";


Get the first N elements of an array?

if you want to get the first N elements and also remove it from the array, you can use array_splice() (note the 'p' in "splice"):

use it like so: $array_without_n_elements = array_splice($old_array, 0, N)

Get top most UIViewController

you can define a UIViewController variable in AppDelegate, and in every viewWillAppear set the variable to self.(however dianz answer is the best answer.)

override func viewWillAppear(animated: Bool) {
    let appDel = UIApplication.sharedApplication().delegate as! AppDelegate
    appDel.currentVC = self

Get input type="file" value when it has multiple files selected

You use input.files property. It's a collection of File objects and each file has a name property:

onmouseout="for (var i = 0; i < this.files.length; i++) alert(this.files[i].name);"

CSS-moving text from left to right

You could simply use CSS animated text generator. There are pre-created templates already

Convert dataframe column to 1 or 0 for "true"/"false" values and assign to dataframe

Even when you asked finally for the opposite, to reform 0s and 1s into Trues and Falses, however, I post an answer about how to transform falses and trues into ones and zeros (1s and 0s), for a whole dataframe, in a single line.

Example given

df <- structure(list(p1_1 = c(TRUE, FALSE, FALSE, NA, TRUE, FALSE, 
                NA), p1_2 = c(FALSE, TRUE, FALSE, NA, FALSE, NA, 
                TRUE), p1_3 = c(TRUE, 
                TRUE, FALSE, NA, NA, FALSE, TRUE), p1_4 = c(FALSE, NA, 
                FALSE,  FALSE, TRUE, FALSE, NA), p1_5 = c(TRUE, NA, 
                FALSE, TRUE, FALSE, NA, TRUE), p1_6 = c(TRUE, NA, 
                FALSE, TRUE, FALSE, NA, TRUE), p1_7 = c(TRUE, NA, 
                FALSE, TRUE, NA, FALSE, TRUE), p1_8 = c(FALSE, 
                FALSE, NA, FALSE, TRUE, FALSE, NA), p1_9 = c(TRUE, 
                FALSE,  NA, FALSE, FALSE, NA, TRUE), p1_10 = c(TRUE, 
                FALSE, NA, FALSE, FALSE, NA, TRUE), p1_11 = c(FALSE, 
                FALSE, NA, FALSE, NA, FALSE, TRUE)), .Names = 
                c("p1_1", "p1_2", "p1_3", "p1_4", "p1_5", "p1_6", 
                "p1_7", "p1_8", "p1_9", "p1_10", "p1_11"), row.names = 
                 c(NA, -7L), class = "data.frame")

   p1_1  p1_2  p1_3  p1_4  p1_5  p1_6  p1_7  p1_8  p1_9 p1_10 p1_11

Then by running that: df * 1 all Falses and Trues are trasnformed into 1s and 0s. At least, this was happen in the R version that I have (R version 3.4.4 (2018-03-15) ).

> df*1
  p1_1 p1_2 p1_3 p1_4 p1_5 p1_6 p1_7 p1_8 p1_9 p1_10 p1_11
1    1    0    1    0    1    1    1    0    1     1     0
2    0    1    1   NA   NA   NA   NA    0    0     0     0
3    0    0    0    0    0    0    0   NA   NA    NA    NA
4   NA   NA   NA    0    1    1    1    0    0     0     0
5    1    0   NA    1    0    0   NA    1    0     0    NA
6    0   NA    0    0   NA   NA    0    0   NA    NA     0
7   NA    1    1   NA    1    1    1   NA    1     1     1

I do not know if it a total "safe" command, under all different conditions / dfs.

How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?

All of the answers so far ignore a dangerous problem with ===. It has been noted in passing, but not stressed, that integer and double are different types, so the following code:

$n = 1000;
$d = $n + 0.0e0;
echo '<br/>'. ( ($n ==  $d)?'equal' :'not equal' );
echo '<br/>'. ( ($n === $d)?'equal' :'not equal' );


 not equal

Note that this is NOT a case of a "rounding error". The two numbers are exactly equal down to the last bit, but they have different types.

This is a nasty problem because a program using === can run happily for years if all of the numbers are small enough (where "small enough" depends on the hardware and OS you are running on). However, if by chance, an integer happens to be large enough to be converted to a double, its type is changed "forever" even though a subsequent operation, or many operations, might bring it back to a small integer in value. And, it gets worse. It can spread - double-ness infection can be passed along to anything it touches, one calculation at a time.

In the real world, this is likely to be a problem in programs that handle dates beyond the year 2038, for example. At this time, UNIX timestamps (number of seconds since 1970-01-01 00:00:00 UTC) will require more than 32-bits, so their representation will "magically" switch to double on some systems. Therefore, if you calculate the difference between two times you might end up with a couple of seconds, but as a double, rather than the integer result that occurs in the year 2017.

I think this is much worse than conversions between strings and numbers because it is subtle. I find it easy to keep track of what is a string and what is a number, but keeping track of the number of bits in a number is beyond me.

So, in the above answers there are some nice tables, but no distinction between 1 (as an integer) and 1 (subtle double) and 1.0 (obvious double). Also, advice that you should always use === and never == is not great because === will sometimes fail where == works properly. Also, JavaScript is not equivalent in this regard because it has only one number type (internally it may have different bit-wise representations, but it does not cause problems for ===).

My advice - use neither. You need to write your own comparison function to really fix this mess.

Bash script processing limited number of commands in parallel

Use the wait built-in:

process1 &
process2 &
process3 &
process4 &
process5 &
process6 &
process7 &
process8 &

For the above example, 4 processes process1 ... process4 would be started in the background, and the shell would wait until those are completed before starting the next set.

From the GNU manual:

wait [jobspec or pid ...]

Wait until the child process specified by each process ID pid or job specification jobspec exits and return the exit status of the last command waited for. If a job spec is given, all processes in the job are waited for. If no arguments are given, all currently active child processes are waited for, and the return status is zero. If neither jobspec nor pid specifies an active child process of the shell, the return status is 127.

Compiling a C++ program with gcc

If you give the code a .c extension the compiler thinks it is C code, not C++. And the C++ compiler driver is called g++, if you use the gcc driver you will have linker problems, as the standard C++ libraries will not be linked by default. So you want:

g++ myprog.cpp

And do not even consider using an uppercase .C extension, unless you never want to port your code, and are prepared to be hated by those you work with.

Java 8 Iterable.forEach() vs foreach loop

The better practice is to use for-each. Besides violating the Keep It Simple, Stupid principle, the new-fangled forEach() has at least the following deficiencies:

  • Can't use non-final variables. So, code like the following can't be turned into a forEach lambda:
Object prev = null;
for(Object curr : list)
    if( prev != null )
        foo(prev, curr);
    prev = curr;
  • Can't handle checked exceptions. Lambdas aren't actually forbidden from throwing checked exceptions, but common functional interfaces like Consumer don't declare any. Therefore, any code that throws checked exceptions must wrap them in try-catch or Throwables.propagate(). But even if you do that, it's not always clear what happens to the thrown exception. It could get swallowed somewhere in the guts of forEach()

  • Limited flow-control. A return in a lambda equals a continue in a for-each, but there is no equivalent to a break. It's also difficult to do things like return values, short circuit, or set flags (which would have alleviated things a bit, if it wasn't a violation of the no non-final variables rule). "This is not just an optimization, but critical when you consider that some sequences (like reading the lines in a file) may have side-effects, or you may have an infinite sequence."

  • Might execute in parallel, which is a horrible, horrible thing for all but the 0.1% of your code that needs to be optimized. Any parallel code has to be thought through (even if it doesn't use locks, volatiles, and other particularly nasty aspects of traditional multi-threaded execution). Any bug will be tough to find.

  • Might hurt performance, because the JIT can't optimize forEach()+lambda to the same extent as plain loops, especially now that lambdas are new. By "optimization" I do not mean the overhead of calling lambdas (which is small), but to the sophisticated analysis and transformation that the modern JIT compiler performs on running code.

  • If you do need parallelism, it is probably much faster and not much more difficult to use an ExecutorService. Streams are both automagical (read: don't know much about your problem) and use a specialized (read: inefficient for the general case) parallelization strategy (fork-join recursive decomposition).

  • Makes debugging more confusing, because of the nested call hierarchy and, god forbid, parallel execution. The debugger may have issues displaying variables from the surrounding code, and things like step-through may not work as expected.

  • Streams in general are more difficult to code, read, and debug. Actually, this is true of complex "fluent" APIs in general. The combination of complex single statements, heavy use of generics, and lack of intermediate variables conspire to produce confusing error messages and frustrate debugging. Instead of "this method doesn't have an overload for type X" you get an error message closer to "somewhere you messed up the types, but we don't know where or how." Similarly, you can't step through and examine things in a debugger as easily as when the code is broken into multiple statements, and intermediate values are saved to variables. Finally, reading the code and understanding the types and behavior at each stage of execution may be non-trivial.

  • Sticks out like a sore thumb. The Java language already has the for-each statement. Why replace it with a function call? Why encourage hiding side-effects somewhere in expressions? Why encourage unwieldy one-liners? Mixing regular for-each and new forEach willy-nilly is bad style. Code should speak in idioms (patterns that are quick to comprehend due to their repetition), and the fewer idioms are used the clearer the code is and less time is spent deciding which idiom to use (a big time-drain for perfectionists like myself!).

As you can see, I'm not a big fan of the forEach() except in cases when it makes sense.

Particularly offensive to me is the fact that Stream does not implement Iterable (despite actually having method iterator) and cannot be used in a for-each, only with a forEach(). I recommend casting Streams into Iterables with (Iterable<T>)stream::iterator. A better alternative is to use StreamEx which fixes a number of Stream API problems, including implementing Iterable.

That said, forEach() is useful for the following:

  • Atomically iterating over a synchronized list. Prior to this, a list generated with Collections.synchronizedList() was atomic with respect to things like get or set, but was not thread-safe when iterating.

  • Parallel execution (using an appropriate parallel stream). This saves you a few lines of code vs using an ExecutorService, if your problem matches the performance assumptions built into Streams and Spliterators.

  • Specific containers which, like the synchronized list, benefit from being in control of iteration (although this is largely theoretical unless people can bring up more examples)

  • Calling a single function more cleanly by using forEach() and a method reference argument (ie, list.forEach (obj::someMethod)). However, keep in mind the points on checked exceptions, more difficult debugging, and reducing the number of idioms you use when writing code.

Articles I used for reference:

EDIT: Looks like some of the original proposals for lambdas (such as Google Cache) solved some of the issues I mentioned (while adding their own complications, of course).

How to target only IE (any version) within a stylesheet?

Another working solution for IE specific styling is

<html data-useragent="Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)">

And then your selector

html[data-useragent*='MSIE 10.0'] body .my-class{
        margin-left: -0.4em;

Better way to find index of item in ArrayList?

Use indexOf() method to find first occurrence of the element in the collection.

Replace all whitespace with a line break/paragraph mark to make a word list

You could use POSIX [[:blank:]] to match a horizontal white-space character.

sed 's/[[:blank:]]\+/\n/g' file

or you may use [[:space:]] instead of [[:blank:]] also.


$ echo 'this  is a sentence' | sed 's/[[:blank:]]\+/\n/g'

Multi-key dictionary in c#?

Here's another example using the Tuple class with the Dictionary.

        // Setup Dictionary
    Dictionary<Tuple<string, string>, string> testDictionary = new Dictionary<Tuple<string, string>, string>
        {new Tuple<string, string>("key1","key2"), "value1"},
        {new Tuple<string, string>("key1","key3"), "value2"},
        {new Tuple<string, string>("key2","key3"), "value3"}
    //Query Dictionary
    public string FindValue(string stuff1, string stuff2)
        return testDictionary[Tuple.Create(stuff1, stuff2)];

How to HTML encode/escape a string? Is there a built-in?

ERB::Util.html_escape can be used anywhere. It is available without using require in Rails.

What is the Angular equivalent to an AngularJS $watch?

You can use getter function or get accessor to act as watch on angular 2.

See demo here.

import {Component} from 'angular2/core';

  // Declare the tag name in index.html to where the component attaches
  selector: 'hello-world',

  // Location of the template for this component
  template: `
  <button (click)="OnPushArray1()">Push 1</button>
    I'm array 1 {{ array1 | json }}
  <button (click)="OnPushArray2()">Push 2</button>
    I'm array 2 {{ array2 | json }}
  I'm concatenated {{ concatenatedArray | json }}
    I'm length of two arrays {{ arrayLength | json }}
export class HelloWorld {
    array1: any[] = [];
    array2: any[] = [];

    get concatenatedArray(): any[] {
      return this.array1.concat(this.array2);

    get arrayLength(): number {
      return this.concatenatedArray.length;

    OnPushArray1() {

    OnPushArray2() {

Find the division remainder of a number

From Python 3.7, there is a new math.remainder() function:

from math import remainder


-2.0  # not 5

Note, as above, it's not the same as %.

Quoting the documentation:

math.remainder(x, y)

Return the IEEE 754-style remainder of x with respect to y. For finite x and finite nonzero y, this is the difference x - n*y, where n is the closest integer to the exact value of the quotient x / y. If x / y is exactly halfway between two consecutive integers, the nearest even integer is used for n. The remainder r = remainder(x, y) thus always satisfies abs(r) <= 0.5 * abs(y).

Special cases follow IEEE 754: in particular, remainder(x, math.inf) is x for any finite x, and remainder(x, 0) and remainder(math.inf, x) raise ValueError for any non-NaN x. If the result of the remainder operation is zero, that zero will have the same sign as x.

On platforms using IEEE 754 binary floating-point, the result of this operation is always exactly representable: no rounding error is introduced.

Issue29962 describes the rationale for creating the new function.

How to get all of the immediate subdirectories in Python

import os
def get_immediate_subdirectories(a_dir):
    return [name for name in os.listdir(a_dir)
            if os.path.isdir(os.path.join(a_dir, name))]

What is limiting the # of simultaneous connections my ASP.NET application can make to a web service?

Have you tried to set the value of the static DefaultConnectionLimit property programmatically?

Here is a good source of information about that true headache... ASP.NET Thread Usage on IIS 7.5, IIS 7.0, and IIS 6.0, with updates for framework 4.0.

Using Apache httpclient for https

According to the documentation you need to specify the key store:

Protocol authhttps = new Protocol("https",  
      new AuthSSLProtocolSocketFactory(
          new URL("file:my.keystore"), "mypassword",
          new URL("file:my.truststore"), "mypassword"), 443); 

 HttpClient client = new HttpClient();
 client.getHostConfiguration().setHost("localhost", 443, authhttps);

Tomcat Server not starting with in 45 seconds

In my case I was using spring+hibernate and forgot to run my MYSQL server due to which hibernate was not getting loaded and thus was throwing error

Jquery button click() function is not working

After making the id unique across the document ,You have to use event delegation

$("#container").on("click", "buttonid", function () {

ADB error: cannot connect to daemon

If nothing works Restart your PC . Restarting my computer does the trick

How do I do logging in C# without using 3rd party libraries?

I used to write my own error logging until I discovered ELMAH. I've never been able to get the emailing part down quite as perfectly as ELMAH does.

Can not run Java Applets in Internet Explorer 11 using JRE 7u51

We see the same problem with Java 7u51, IE11 and Windows 8.1. As detailed at and and in a bug report submitted to Oracle on 17 January 2014 we find that all is OK until you agree to Java making changes to your system after installation. Once you allow the post-installation permission, Java is disabled. Other than constantly fighting off permission requests, the only workarounds we've found are to use a different environment: browser (use Firefox or Chrome), OS (use Windows 7) or Java version (use a Java 8 build).

How to split data into trainset and testset randomly?

sklearn.cross_validation is deprecated since version 0.18, instead you should use sklearn.model_selection as show below

from sklearn.model_selection import train_test_split
import numpy

with open("datafile.txt", "rb") as f:
   data ='\n')
   data = numpy.array(data)  #convert array to numpy type array

   x_train ,x_test = train_test_split(data,test_size=0.5)       #test_size=0.5(whole_data)

Finding even or odd ID values

ID % 2 is checking what the remainder is if you divide ID by 2. If you divide an even number by 2 it will always have a remainder of 0. Any other number (odd) will result in a non-zero value. Which is what is checking for.

Split string into array

You can try this:

var entryArray =

How can I make a button have a rounded border in Swift?

To do this job in storyboard (Interface Builder Inspector)

With help of IBDesignable, we can add more options to Interface Builder Inspector for UIButton and tweak them on storyboard. First, add the following code to your project.

@IBDesignable extension UIButton {

    @IBInspectable var borderWidth: CGFloat {
        set {
            layer.borderWidth = newValue
        get {
            return layer.borderWidth

    @IBInspectable var cornerRadius: CGFloat {
        set {
            layer.cornerRadius = newValue
        get {
            return layer.cornerRadius

    @IBInspectable var borderColor: UIColor? {
        set {
            guard let uiColor = newValue else { return }
            layer.borderColor = uiColor.cgColor
        get {
            guard let color = layer.borderColor else { return nil }
            return UIColor(cgColor: color)

Then simply set the attributes for buttons on storyboard.

enter image description here

Seaborn Barplot - Displaying Values

A simple way to do so is to add the below code (for Seaborn):

for p in splot.patches:
    splot.annotate(format(p.get_height(), '.1f'), 
                   (p.get_x() + p.get_width() / 2., p.get_height()), 
                   ha = 'center', va = 'center', 
                   xytext = (0, 9), 
                   textcoords = 'offset points') 

Example :

splot = sns.barplot(df['X'], df['Y'])
# Annotate the bars in plot
for p in splot.patches:
    splot.annotate(format(p.get_height(), '.1f'), 
                   (p.get_x() + p.get_width() / 2., p.get_height()), 
                   ha = 'center', va = 'center', 
                   xytext = (0, 9), 
                   textcoords = 'offset points')

How to concatenate int values in java?

Michael Borgwardt's solution is the best for 5 digits, but if you have variable number of digits, you can use something like this:

public static String concatenateDigits(int... digits) {
   StringBuilder sb = new StringBuilder(digits.length);
   for (int digit : digits) {
   return sb.toString();

Currency formatting in Python

See the locale module.

This does currency (and date) formatting.

>>> import locale
>>> locale.setlocale( locale.LC_ALL, '' )
'English_United States.1252'
>>> locale.currency( 188518982.18 )
>>> locale.currency( 188518982.18, grouping=True )

How do you disable the unused variable warnings coming out of gcc in 3rd party code I do not wish to edit?

The -Wno-unused-variable switch usually does the trick. However, that is a very useful warning indeed if you care about these things in your project. It becomes annoying when GCC starts to warn you about things not in your code though.

I would recommend you keeping the warning on, but use -isystem instead of -I for include directories of third-party projects. That flag tells GCC not to warn you about the stuff you have no control over.

For example, instead of -IC:\\boost_1_52_0, say -isystem C:\\boost_1_52_0.

Hope it helps. Good Luck!

Memory errors and list limits?

First off, see How Big can a Python Array Get? and Numpy, problem with long arrays

Second, the only real limit comes from the amount of memory you have and how your system stores memory references. There is no per-list limit, so Python will go until it runs out of memory. Two possibilities:

  1. If you are running on an older OS or one that forces processes to use a limited amount of memory, you may need to increase the amount of memory the Python process has access to.
  2. Break the list apart using chunking. For example, do the first 1000 elements of the list, pickle and save them to disk, and then do the next 1000. To work with them, unpickle one chunk at a time so that you don't run out of memory. This is essentially the same technique that databases use to work with more data than will fit in RAM.

How to edit my Excel dropdown list?

Attribute_Brands is a named range.

On any worksheet (tab) press F5 and type Attribute_Brands into the reference box and click on the OK button.

This will take you to the named range.

The data in it can be updated by typing new values into the cells.

The named range can be altered via the 'Insert - Name - Define' menu.

Remove Project from Android Studio

  1. Go to your Android project directory



  2. Delete which one you need to delete

  3. Restart Android Studio

Python locale error: unsupported locale setting

You probably do not have any de_DE locale available.

You can view a list of available locales with the locale -a command. For example, on my machine:

$ locale -a

Note that if you want to set the locale to it_IT you must also specify the .utf8:

>>> import locale
>>> locale.setlocale(locale.LC_ALL, 'it_IT')   # error!
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/", line 539, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting
>>> locale.setlocale(locale.LC_ALL, 'it_IT.utf8')

To install a new locale use:

sudo apt-get install language-pack-id

where id is the language code (taken from here)

After you have installed the locale you should follow Julien Palard advice and reconfigure the locales with:

sudo dpkg-reconfigure locales

How to get value of Radio Buttons?

An alterntive is to use an enum and a component class that extends the standard RadioButton.

public enum Genders

public partial class GenderRadioButton : RadioButton
    public GenderRadioButton()

    public GenderRadioButton (IContainer container)


    public Genders gender{ get; set; }

Use a common event handler for the GenderRadioButtons

private void Gender_CheckedChanged(Object sender, EventArgs e)
    if (((RadioButton)sender).Checked)
        //get selected value
        Genders myGender = ((GenderRadioButton)sender).Gender;
        //get the name of the enum value
        string GenderName = Enum.GetName(typeof(Genders ), myGender);
        //do any work required when you change gender
        switch (myGender)
            case Genders.Male:
            case Genders.Female:

Failed to connect to mysql at with user root access denied for user 'root'@'localhost'(using password:YES)

Access the database as a user administrator (root user maybe). Check the right one user privileges to the database.

mysql >SHOW GRANTS FOR <username>;

Assign full user privileges to the database from localhost

mysql> GRANT ALL PRIVILEGES ON <databasename>.* TO '<username>'@'localhost' IDENTIFIED BY '<password>';

in case of error in connecting to the database from third-party programs, for example MySQL WORKBENCH, assign privileges to the user to the database from any host MYSQL Grant all privileges to database from any host

mysql> GRANT ALL PRIVILEGES ON <databasename>.* TO '<username>'@'%' IDENTIFIED BY '<password>';

MVC 4 - Return error message from Controller - Show in View

Thanks for all the replies.

I was able to solve this by doing the following:


public ActionResult form_edit(FormModels model)
  model.error_msg = model.update_content(model);
  return RedirectToAction("Form_edit", "Form", model);

public ActionResult form_edit(FormModels model, string searchString,string id)
  string test = model.selectedvalue;
  var bal = new FormModels();
  bal.Countries = bal.get_contentdetails(searchString);
  bal.selectedvalue = id;
  bal.dd_text = "content_name";
  bal.dd_value = "content_id";

  test = model.error_msg;
  ViewBag.head = "Heading";

  if (model.error_msg != null)
    ModelState.AddModelError("error_msg", test);

  model.error_msg = "";
  return View(bal);


@using (Html.BeginForm("form_edit", "Form", FormMethod.Post))
        @Html.DisplayNameFor(model => model.content_name)
        @Html.DropDownListFor(x => x.selectedvalue, new SelectList(Model.Countries, Model.dd_value, Model.dd_text), "-- Select Product--")

Cannot create cache directory .. or directory is not writable. Proceeding without cache in Laravel

I had the same problem today. Try it!

sudo chown -R  [yourgroup]  /home/[youruser]/.composer/cache/repo/

sudo chown -R  [yourgroup]   /home/[youruser]/.composer/cache/files/

Access to the path is denied

What Identity is your Application Pool for the Web application running as, to troubleshoot, try creating a new App Pool with say Network Service as its identity and make your web application use that new App Pool you created and see if the error persists.

How to install pip for Python 3.6 on Ubuntu 16.10?

Let's suppose that you have a system running Ubuntu 16.04, 16.10, or 17.04, and you want Python 3.6 to be the default Python.

If you're using Ubuntu 16.04 LTS, you'll need to use a PPA:

sudo add-apt-repository ppa:jonathonf/python-3.6  # (only for 16.04 LTS)

Then, run the following (this works out-of-the-box on 16.10 and 17.04):

sudo apt update
sudo apt install python3.6
sudo apt install python3.6-dev
sudo apt install python3.6-venv
sudo python3.6
sudo ln -s /usr/bin/python3.6 /usr/local/bin/python3
sudo ln -s /usr/local/bin/pip /usr/local/bin/pip3

# Do this only if you want python3 to be the default Python
# instead of python2 (may be dangerous, esp. before 2020):
# sudo ln -s /usr/bin/python3.6 /usr/local/bin/python

When you have completed all of the above, each of the following shell commands should indicate Python 3.6.1 (or a more recent version of Python 3.6):

python --version   # (this will reflect your choice, see above)
python3 --version
$(head -1 `which pip` | tail -c +3) --version
$(head -1 `which pip3` | tail -c +3) --version

How to disable the resize grabber of <textarea>?

<textarea style="resize:none" name="name" cols="num" rows="num"></textarea>

Just an example

Circular (or cyclic) imports in Python

Circular imports can be confusing because import does two things:

  1. it executes imported module code
  2. adds imported module to importing module global symbol table

The former is done only once, while the latter at each import statement. Circular import creates situation when importing module uses imported one with partially executed code. In consequence it will not see objects created after import statement. Below code sample demonstrates it.

Circular imports are not the ultimate evil to be avoided at all cost. In some frameworks like Flask they are quite natural and tweaking your code to eliminate them does not make the code better.

print 'import b'
import b
print 'a in globals() {}'.format('a' in globals())
print 'import a'
import a
print 'a in globals() {}'.format('a' in globals())
if __name__ == '__main__':
    print 'imports done'
    print 'b has y {}, a is b.a {}'.format(hasattr(b, 'y'), a is b.a)

print "b in, __name__ = {}".format(__name__)
x = 3
print 'b imports a'
import a
y = 5
print "b out"

print 'a in, __name__ = {}'.format(__name__)
print 'a imports b'
import b
print 'b has x {}'.format(hasattr(b, 'x'))
print 'b has y {}'.format(hasattr(b, 'y'))
print "a out"

python output with comments

import b
b in, __name__ = b    # b code execution started
b imports a
a in, __name__ = a    # a code execution started
a imports b           # b code execution is already in progress
b has x True
b has y False         # b defines y after a import,
a out
b out
a in globals() False  # import only adds a to main global symbol table 
import a
a in globals() True
imports done
b has y True, a is b.a True # all b objects are available

How to pass parameters to maven build using pom.xml?

If we have parameter like below in our POM XML


I run maven command line as follows :

mvn clean install package -Dproject.version=10 -Dsvn.version=1

List all employee's names and their managers by manager name using an inner join

No, the correct join is:

inner join Employees m on e.mgr = m.EmpID;

You need to match the ManagerID for the current employee with the EmployeeID of the manager. Not with the ManagerID of the manager.

As noted by Andrey Gordeev:
You'd also need to add m.Ename to your SELECT query in order to get the name of the Manager in your result. Otherwise you'd only get the managerID.

How to upload a file and JSON data in Postman?

Postman multipart form-data content-type

Select [Content Type] from [SHOW COLUMNS] then set content-type of "application/json" to the parameter of json text.

Count records for every month in a year

Try This query:

  SUM(CASE datepart(month,ARR_DATE) WHEN 1 THEN 1 ELSE 0 END) AS 'January',
  SUM(CASE datepart(month,ARR_DATE) WHEN 2 THEN 1 ELSE 0 END) AS 'February',
  SUM(CASE datepart(month,ARR_DATE) WHEN 3 THEN 1 ELSE 0 END) AS 'March',
  SUM(CASE datepart(month,ARR_DATE) WHEN 4 THEN 1 ELSE 0 END) AS 'April',
  SUM(CASE datepart(month,ARR_DATE) WHEN 5 THEN 1 ELSE 0 END) AS 'May',
  SUM(CASE datepart(month,ARR_DATE) WHEN 6 THEN 1 ELSE 0 END) AS 'June',
  SUM(CASE datepart(month,ARR_DATE) WHEN 7 THEN 1 ELSE 0 END) AS 'July',
  SUM(CASE datepart(month,ARR_DATE) WHEN 8 THEN 1 ELSE 0 END) AS 'August',
  SUM(CASE datepart(month,ARR_DATE) WHEN 9 THEN 1 ELSE 0 END) AS 'September',
  SUM(CASE datepart(month,ARR_DATE) WHEN 10 THEN 1 ELSE 0 END) AS 'October',
  SUM(CASE datepart(month,ARR_DATE) WHEN 11 THEN 1 ELSE 0 END) AS 'November',
  SUM(CASE datepart(month,ARR_DATE) WHEN 12 THEN 1 ELSE 0 END) AS 'December',
  SUM(CASE datepart(year,ARR_DATE) WHEN 2012 THEN 1 ELSE 0 END) AS 'TOTAL'
  ARR_DATE BETWEEN '2012/01/01' AND '2012/12/31' 

Add element to a JSON file?

alternatively you can do

iter(data).next()['f'] = var

Calculate a MD5 hash from a string

I suppose it is better to use UTF-8 encoding in the string MD5.

public static string MD5(this string s)
    using (var provider = System.Security.Cryptography.MD5.Create())
        StringBuilder builder = new StringBuilder();                           

        foreach (byte b in provider.ComputeHash(Encoding.UTF8.GetBytes(s)))

        return builder.ToString();

How do I redirect with JavaScript?

You can't redirect to a function. What you can do is pass some flag on the URL when redirecting, then check that flag in the server side code and if raised, execute the function.

For example:

document.location = "MyPage.php?action=DoThis";

Then in your PHP code check for "action" in the query string and if equal to "DoThis" execute whatever function you need.

System.web.mvc missing

Easiest way to solve this problem is install ASP.NET MVC 3 from Web Platforms installer.

enter image description here

Or by using Nuget command

Install-Package Microsoft.AspNet.Mvc -Version 3.0.50813.1

Graphical HTTP client for windows

Update: For people that still come across this, Postman is your best bet now:

RestClient is my favorite. It's Java based. I think it should meet your needs quite nicely. I particularly like the Auth suppport.

Screen Shot

Adding items to a JComboBox

Wrap the values in a class and override the toString() method.

class ComboItem
    private String key;
    private String value;

    public ComboItem(String key, String value)
        this.key = key;
        this.value = value;

    public String toString()
        return key;

    public String getKey()
        return key;

    public String getValue()
        return value;

Add the ComboItem to your comboBox.

comboBox.addItem(new ComboItem("Visible String 1", "Value 1"));
comboBox.addItem(new ComboItem("Visible String 2", "Value 2"));
comboBox.addItem(new ComboItem("Visible String 3", "Value 3"));

Whenever you get the selected item.

Object item = comboBox.getSelectedItem();
String value = ((ComboItem)item).getValue();

How to change XAMPP apache server port?

Have you tried to access your page by typing "http://localhost:8012" (after restarting the apache)?

ASP.NET MVC Ajax Error handling

In agreement with aleho's response here's a complete example. It works like a charm and is super simple.

Controller code

public async Task<ActionResult> ChildItems()
    var client = TranslationDataHttpClient.GetClient();
    HttpResponseMessage response = await client.GetAsync("childItems);

    if (response.IsSuccessStatusCode)
            string content = response.Content.ReadAsStringAsync().Result;
            List<WorkflowItem> parameters = JsonConvert.DeserializeObject<List<WorkflowItem>>(content);
            return Json(content, JsonRequestBehavior.AllowGet);
            return new HttpStatusCodeResult(response.StatusCode, response.ReasonPhrase);

Javascript code in the view

var url = '@Html.Raw(@Url.Action("ChildItems", "WorkflowItemModal")';

    type: "GET",
    dataType: "json",
    url: url,
    contentType: "application/json; charset=utf-8",
    success: function (data) {
        // Do something with the returned data
    error: function (xhr, status, error) {
        // Handle the error.

Hope this helps someone else!

How to Lock Android App's Orientation to Portrait in Phones and Landscape in Tablets?

Just Add:


in "AndroidManifest.xml" :


is python capable of running on multiple cores?

Threads share a process and a process runs on a core, but you can use python's multiprocessing module to call your functions in separate processes and use other cores, or you can use the subprocess module, which can run your code and non-python code too.

Add space between two particular <td>s

None of the answers worked for me. The simplest way would be to add <td>s in between with width = 5px and background='white' or whatever the background color of the page is.

Again this will fail in case you have a list of <th>s representing table headers.

is it possible to get the MAC address for machine using nmap

nmap can discover the MAC address of a remote target only if

  • the target is on the same link as the machine nmap runs on, or
  • the target leaks this information through SNMP, NetBIOS etc.

Another possibility comes with IPv6 if the target uses EUI-64 identifiers, then the MAC address can be deduced from the IP address.

Apart from the above possibilities, there is no reliable way to obtain the MAC address of a remote target with network scanning techniques.

PHPMailer: SMTP Error: Could not connect to SMTP host

In my case in CPANEL i have 'Register mail ids' option where i add my email address and after 30 minutes it works fine with simple php mail function.

Check if Internet Connection Exists with jQuery?

The best option for your specific case might be:

Right before your close </body> tag:

<script src=""></script>
<script>window.jQuery || document.write('<script src="js/vendor/jquery-1.10.2.min.js"><\/script>')</script>

This is probably the easiest way given that your issue is centered around jQuery.

If you wanted a more robust solution you could try:

var online = navigator.onLine;

Read more about the W3C's spec on offline web apps, however be aware that this will work best in modern web browsers, doing so with older web browsers may not work as expected, or at all.

Alternatively, an XHR request to your own server isn't that bad of a method for testing your connectivity. Considering one of the other answers state that there are too many points of failure for an XHR, if your XHR is flawed when establishing it's connection then it'll also be flawed during routine use anyhow. If your site is unreachable for any reason, then your other services running on the same servers will likely be unreachable also. That decision is up to you.

I wouldn't recommend making an XHR request to someone else's service, even for that matter. Make the request to your server, or not at all.

What does it mean to be "online"?

There seems to be some confusion around what being "online" means. Consider that the internet is a bunch of networks, however sometimes you're on a VPN, without access to the internet "at-large" or the world wide web. Often companies have their own networks which have limited connectivity to other external networks, therefore you could be considered "online". Being online only entails that you are connected to a network, not the availability nor reachability of the services you are trying to connect to.

To determine if a host is reachable from your network, you could do this:

function hostReachable() {

  // Handle IE and more capable browsers
  var xhr = new ( window.ActiveXObject || XMLHttpRequest )( "Microsoft.XMLHTTP" );

  // Open new request as a HEAD to the root hostname with a random param to bust the cache "HEAD", "//" + window.location.hostname + "/?rand=" + Math.floor((1 + Math.random()) * 0x10000), false );

  // Issue request and handle response
  try {
    return ( xhr.status >= 200 && (xhr.status < 300 || xhr.status === 304) );
  } catch (error) {
    return false;


You can also find the Gist for that here:

Details on local implementation

Some people have commented, "I'm always being returned false". That's because you're probably testing it out on your local server. Whatever server you're making the request to, you'll need to be able to respond to the HEAD request, that of course can be changed to a GET if you want.

What's the difference between KeyDown and KeyPress in .NET?

From MSDN:

Key events occur in the following order:

  1. KeyDown

  2. KeyPress

  3. KeyUp

Furthermore, KeyPress gives you a chance to declare the action as "handled" to prevent it from doing anything.

Simple 3x3 matrix inverse code (C++)

With all due respect to our unknown (yahoo) poster, I look at code like that and just die a little inside. Alphabet soup is just so insanely difficult to debug. A single typo anywhere in there can really ruin your whole day. Sadly, this particular example lacked variables with underscores. It's so much more fun when we have a_b-c_d*e_f-g_h. Especially when using a font where _ and - have the same pixel length.

Taking up Suvesh Pratapa on his suggestion, I note:

Given 3x3 matrix:
       y0x0  y0x1  y0x2
       y1x0  y1x1  y1x2
       y2x0  y2x1  y2x2
Declared as double matrix [/*Y=*/3] [/*X=*/3];

(A) When taking a minor of a 3x3 array, we have 4 values of interest. The lower X/Y index is always 0 or 1. The higher X/Y index is always 1 or 2. Always! Therefore:

double determinantOfMinor( int          theRowHeightY,
                           int          theColumnWidthX,
                           const double theMatrix [/*Y=*/3] [/*X=*/3] )
  int x1 = theColumnWidthX == 0 ? 1 : 0;  /* always either 0 or 1 */
  int x2 = theColumnWidthX == 2 ? 1 : 2;  /* always either 1 or 2 */
  int y1 = theRowHeightY   == 0 ? 1 : 0;  /* always either 0 or 1 */
  int y2 = theRowHeightY   == 2 ? 1 : 2;  /* always either 1 or 2 */

  return ( theMatrix [y1] [x1]  *  theMatrix [y2] [x2] )
      -  ( theMatrix [y1] [x2]  *  theMatrix [y2] [x1] );

(B) Determinant is now: (Note the minus sign!)

double determinant( const double theMatrix [/*Y=*/3] [/*X=*/3] )
  return ( theMatrix [0] [0]  *  determinantOfMinor( 0, 0, theMatrix ) )
      -  ( theMatrix [0] [1]  *  determinantOfMinor( 0, 1, theMatrix ) )
      +  ( theMatrix [0] [2]  *  determinantOfMinor( 0, 2, theMatrix ) );

(C) And the inverse is now:

bool inverse( const double theMatrix [/*Y=*/3] [/*X=*/3],
                    double theOutput [/*Y=*/3] [/*X=*/3] )
  double det = determinant( theMatrix );

    /* Arbitrary for now.  This should be something nicer... */
  if ( ABS(det) < 1e-2 )
    memset( theOutput, 0, sizeof theOutput );
    return false;

  double oneOverDeterminant = 1.0 / det;

  for (   int y = 0;  y < 3;  y ++ )
    for ( int x = 0;  x < 3;  x ++   )
        /* Rule is inverse = 1/det * minor of the TRANSPOSE matrix.  *
         * Note (y,x) becomes (x,y) INTENTIONALLY here!              */
      theOutput [y] [x]
        = determinantOfMinor( x, y, theMatrix ) * oneOverDeterminant;

        /* (y0,x1)  (y1,x0)  (y1,x2)  and (y2,x1)  all need to be negated. */
      if( 1 == ((x + y) % 2) )
        theOutput [y] [x] = - theOutput [y] [x];

  return true;

And round it out with a little lower-quality testing code:

void printMatrix( const double theMatrix [/*Y=*/3] [/*X=*/3] )
  for ( int y = 0;  y < 3;  y ++ )
    cout << "[  ";
    for ( int x = 0;  x < 3;  x ++   )
      cout << theMatrix [y] [x] << "  ";
    cout << "]" << endl;
  cout << endl;

void matrixMultiply(  const double theMatrixA [/*Y=*/3] [/*X=*/3],
                      const double theMatrixB [/*Y=*/3] [/*X=*/3],
                            double theOutput  [/*Y=*/3] [/*X=*/3]  )
  for (   int y = 0;  y < 3;  y ++ )
    for ( int x = 0;  x < 3;  x ++   )
      theOutput [y] [x] = 0;
      for ( int i = 0;  i < 3;  i ++ )
        theOutput [y] [x] +=  theMatrixA [y] [i] * theMatrixB [i] [x];

main(int argc, char **argv)
  if ( argc > 1 )
    SRANDOM( atoi( argv[1] ) );

  double m[3][3] = { { RANDOM_D(0,1e3), RANDOM_D(0,1e3), RANDOM_D(0,1e3) },
                     { RANDOM_D(0,1e3), RANDOM_D(0,1e3), RANDOM_D(0,1e3) },
                     { RANDOM_D(0,1e3), RANDOM_D(0,1e3), RANDOM_D(0,1e3) } };
  double o[3][3], mm[3][3];

  if ( argc <= 2 )
    cout << fixed << setprecision(3);

  cout << endl << endl;

  SHOW( determinant(m) );
  cout << endl << endl;

  BOUT( inverse(m, o) );
  cout << endl << endl;

  matrixMultiply (m, o, mm );
  cout << endl << endl;


You may also want to detect very large determinants as round-off errors will affect your accuracy!

How to find locked rows in Oracle

The below PL/SQL block finds all locked rows in a table. The other answers only find the blocking session, finding the actual locked rows requires reading and testing each row.

(However, you probably do not need to run this code. If you're having a locking problem, it's usually easier to find the culprit using GV$SESSION.BLOCKING_SESSION and other related data dictionary views. Please try another approach before you run this abysmally slow code.)

First, let's create a sample table and some data. Run this in session #1.

--Sample schema.
create table test_locking(a number);
insert into test_locking values(1);
insert into test_locking values(2);
update test_locking set a = a+1 where a = 1;

In session #2, create a table to hold the locked ROWIDs.

--Create table to hold locked ROWIDs.
create table locked_rowids(the_rowid rowid);
--Remove old rows if table is already created:
--delete from locked_rowids;

In session #2, run this PL/SQL block to read the entire table, probe each row, and store the locked ROWIDs. Be warned, this may be ridiculously slow. In your real version of this query, change both references to TEST_LOCKING to your own table.

--Save all locked ROWIDs from a table.
--WARNING: This PL/SQL block will be slow and will temporarily lock rows.
--You probably don't need this information - it's usually good enough to know
--what other sessions are locking a statement, which you can find in
    v_resource_busy exception;
    pragma exception_init(v_resource_busy, -00054);
    v_throwaway number;
    type rowid_nt is table of rowid;
    v_rowids rowid_nt := rowid_nt();
    --Loop through all the rows in the table.
    for all_rows in
        select rowid
        from test_locking
    ) loop
        --Try to look each row.
            select 1
            into v_throwaway
            from test_locking
            where rowid = all_rows.rowid
            for update nowait;
        --If it doesn't lock, then record the ROWID.
        exception when v_resource_busy then
            v_rowids(v_rowids.count) := all_rows.rowid;

    end loop;

    --Display count:
    dbms_output.put_line('Rows locked: '||v_rowids.count);

    --Save all the ROWIDs.
    --(Row-by-row because ROWID type is weird and doesn't work in types.)
    for i in 1 .. v_rowids.count loop
        insert into locked_rowids values(v_rowids(i));
    end loop;

Finally, we can view the locked rows by joining to the LOCKED_ROWIDS table.

--Display locked rows.
select *
from test_locking
where rowid in (select the_rowid from locked_rowids);

1 Read error: ssl=0x9524b800: I/O error during system call, Connection reset by peer

Another possible cause for this error message is if the HTTP Method is blocked by the server or load balancer.

It seems to be standard security practice to block unused HTTP Methods. We ran into this because HEAD was being blocked by the load balancer (but, oddly, not all of the load balanced servers, which caused it to fail only some of the time). I was able to test that the request itself worked fine by temporarily changing it to use the GET method.

The error code on iOS was: Error requesting App Code: Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."

Device not detected in Eclipse when connected with USB cable

Do following steps to detect your device in eclipse : -

On Mobile Side:- For Connect USB sync, your Android device needs to have USB Debugging enabled.

To enable Android USB Debugging Mode do following steps :-

Android 2.x - 3.x devices:

Go to Settings > Application > Development > USB Debugging.

Android 4.x devices:

Go to Settings > Developer Options > USB Debugging.

For devices running Android 4.2.2 or later, you may need to unlock Developer Options before it is available within the Menu:

  1. Go to Android home screen.
  2. Pull down the notification bar.
  3. Tap "Settings"
  4. Tap "About Device"
  5. Tap on the "Build Number" button about 7 times.
  6. Developer Mode should now be unlocked and available in Settings > More > Developer Options or in Settings > Developer Options

On PC side

  1. Connect your device to the PC with USB cable.
  2. Download Google USB Driver
  3. Extract/Unzip “” file on your computer (using 7-zip free software, preferably)
  4. Open device manager on your PC
    • Windows 7 & 8 users ? search for Device Manager from Start (or Start screen) and click to open.
    • Windows XP users ? Google it
  5. You will see list of all devices attached to your computer in the device manager. Just find your device (it’ll most probably be in the Other devices list with a yellow exclamation mark by the name of ADB devices), then Right-click on it and select Update Driver Software.
  6. Select “Browse my computer for driver software” in the next window
  7. Now click the “Browse…” button and select the “usb_driver” folder that we extracted in Step 3 from “” file.
  8. Do NOT select the zip file, select the folder where the contents of the zip file are extracted. And keep the Include subfolders box checked
  9. During the installation (as a security check) Windows may ask your permission to install the drivers, click “Install”
  10. Once the installation is complete you’ll see a refreshed list of devices on the Device manager screen showing your phone’s driver installed successfully.

Now in eclipse do following steps to install your app in your device:-

  1. Go to Run > Run Configurations > Target tab.
  2. Check option "Always prompt to pick device". And then running the application from Eclipse,the prompt window finally showed your device.

How do I get a string format of the current date time, in python?

You can use the datetime module for working with dates and times in Python. The strftime method allows you to produce string representation of dates and times with a format you specify.

>>> import datetime
>>>"%B %d, %Y")
'July 23, 2010'
>>>"%I:%M%p on %B %d, %Y")
'10:36AM on July 23, 2010'

How to bind an enum to a combobox control in WPF?

Use ObjectDataProvider:

<ObjectDataProvider x:Key="enumValues"
   MethodName="GetValues" ObjectType="{x:Type System:Enum}">
           <x:Type TypeName="local:ExampleEnum"/>

and then bind to static resource:

ItemsSource="{Binding Source={StaticResource enumValues}}"

based on this article

AngularJS routing without the hash '#'

Lets write answer that looks simple and short

In Router at end add html5Mode(true);

app.config(function($routeProvider,$locationProvider) {

    $routeProvider.when('/home', {


In html head add base tag

    <meta charset="utf-8">    
    <base href="/">

thanks To @plus- for detailing the above answer

How do I get the path of the current executed file in Python?

See my answer to the question Importing modules from parent folder for related information, including why my answer doesn't use the unreliable __file__ variable. This simple solution should be cross-compatible with different operating systems as the modules os and inspect come as part of Python.

First, you need to import parts of the inspect and os modules.

from inspect import getsourcefile
from os.path import abspath

Next, use the following line anywhere else it's needed in your Python code:


How it works:

From the built-in module os (description below), the abspath tool is imported.

OS routines for Mac, NT, or Posix depending on what system we're on.

Then getsourcefile (description below) is imported from the built-in module inspect.

Get useful information from live Python objects.

  • abspath(path) returns the absolute/full version of a file path
  • getsourcefile(lambda:0) somehow gets the internal source file of the lambda function object, so returns '<pyshell#nn>' in the Python shell or returns the file path of the Python code currently being executed.

Using abspath on the result of getsourcefile(lambda:0) should make sure that the file path generated is the full file path of the Python file.
This explained solution was originally based on code from the answer at How do I get the path of the current executed file in Python?.

IE11 meta element Breaks SVG

I figured it out! The page was rendering using IE8 mode... had

<meta http-equiv="X-UA-Compatible" content="IE=8">

in the header... changed it to

<meta http-equiv="X-UA-Compatible" content="IE=9">

9 and it worked!

How to shut down the computer from C#

Different methods:

A. System.Diagnostics.Process.Start("Shutdown", "-s -t 10");

B. Windows Management Instrumentation (WMI)

C. System.Runtime.InteropServices Pinvoke

D. System Management

After I submit, I have seen so many others also have posted...

Difference between readFile() and readFileSync()

'use strict'
var fs = require("fs");

 * implementation of readFileSync
var data = fs.readFileSync('input.txt');
console.log("Program Ended");

 * implementation of readFile 
fs.readFile('input.txt', function (err, data) {
    if (err) return console.error(err);

console.log("Program Ended");

For better understanding run the above code and compare the results..

How to use the 'og' (Open Graph) meta tag for Facebook share

I built a tool for meta generation. It pre-configures entries for Facebook, Google+ and Twitter, and you can use it free here:

To answer the question a bit more, OG tags (Open Graph) tags work similarly to meta tags, and should be placed in the HEAD section of your HTML file. See Facebook's best practises for more information on how to use OG tags effectively.

How can I remove the last character of a string in python?

To remove the last character, just use a slice: my_file_path[:-1]. If you only want to remove a specific set of characters, use my_file_path.rstrip('/'). If you see the string as a file path, the operation is os.path.dirname. If the path is in fact a filename, I rather wonder where the extra slash came from in the first place.

Form Google Maps URL that searches for a specific places near specific coordinates

Yeah, I had the same question for a long time and I found the perfect one. Here are some parameters from it.


Used to specify the search query in Google maps search.
eg : or,-114.01679


Used to specify the location instead of putting it into q. Also has the added effect of allowing you to increase the AddressDetails Accuracy value by being more precise. Mostly only useful if q is a business or suchlike.


Zoom level. Can be set 19 normally, but in certain cases can go up to 23.


Latitude and longitude of the map centre point. Must be in that order. Requires decimal format. Interestingly, you can use this without q, in which case it doesn’t show a marker.


Similar to ll, only this sets the lat/long of the centre point for a business search. Requires the same input criteria as ll.


Sets the kind of map shown. Can be set to:

m – normal  map
k – satellite
h – hybrid
p – terrain


Sets the starting point for directions searches. You can also add text into this in brackets to bold it in the directions sidebar.


Sets the end point for directions searches, and again will bold any text added in brackets.You can also add "+to:" which will set via points. These can be added multiple times.


Allows you to insert via points in directions. Must be in CSV format. For example, via=1,5 addresses 1 and 5 will be via points without entries in the sidebar. The start point (which is set as 0), and 2, 3 and 4 will all show full addresses.


Changes the units used to measure distance (will default to the standard unit in country of origin). Change to ptk for metric or ptm for imperial.


Does stuff with My Maps. Set to 0 show defined My Maps, b to turn the My Maps sidebar on, 1 to show the My Maps tab on its own, or 2 to go to the new My Map creator form.

reference :

ClassCastException, casting Integer to Double

Well the code you've shown doesn't actually include adding any Integers to the ArrayList - but if you do know that you've got integers, you can use:

sum = (double) ((Integer) marks.get(i)).intValue();

That will convert it to an int, which can then be converted to double. You can't just cast directly between the boxed classes.

Note that if you can possibly use generics for your ArrayList, your code will be clearer.

How do you use the ? : (conditional) operator in JavaScript?

It is called the ternary operator

tmp = (foo==1 ? true : false);

how do I give a div a responsive height

I don't think this is the BEST solution, but it does appear to work. Instead of using the background color, I'm going to just embed an image of the background, position it relatively and then wrap the text in a child element and position it absolute - in the centre.

javascript create empty array of a given size

var arr = new Array(5);
console.log(arr.length) // 5

What key shortcuts are to comment and uncomment code?

You can also add the toolbar in Visual Studio to have the buttons available.

View > Toolbars > Text Editor

enter image description here

How to change active class while click to another link in bootstrap use jquery?

You can use cookies for save postback data from one page to another page.After spending a lot time finally i was able to make this happen. I am suggesting my answer to you(this is fully working since I also needed this).

first give your li tag to valid id name like

<ul class="nav nav-list">_x000D_
    <li id="tab1" class="active"><a href="/">Link 1</a></li>_x000D_
    <li id="tab2"><a href="/link2">Link 2</a></li>_x000D_
    <li id="tab3"><a href="/link3">Link 3</a></li>_x000D_

After that copy and paste this script. since I have written some javascript for reading, deleting and creating cookies.

 $('.nav li a').click(function (e) {_x000D_
        var $parent = $(this).parent();_x000D_
        document.cookie = eraseCookie("tab");_x000D_
        document.cookie = createCookie("tab", $parent.attr('id'),0);_x000D_
    $().ready(function () {_x000D_
        var $activeTab = readCookie("tab");_x000D_
        if (!$activeTab =="") {_x000D_
       // alert($activeTab.toString());_x000D_
function createCookie(name, value, days) {_x000D_
    if (days) {_x000D_
        var date = new Date();_x000D_
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));_x000D_
        var expires = "; expires=" + date.toGMTString();_x000D_
    else var expires = "";_x000D_
    document.cookie = name + "=" + value + expires + "; path=/";_x000D_
function readCookie(name) {_x000D_
    var nameEQ = name + "=";_x000D_
    var ca = document.cookie.split(';');_x000D_
    for (var i = 0; i < ca.length; i++) {_x000D_
        var c = ca[i];_x000D_
        while (c.charAt(0) == ' ') c = c.substring(1, c.length);_x000D_
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length);_x000D_
    return null;_x000D_
function eraseCookie(name) {_x000D_
    createCookie(name, "", -1);_x000D_

Note: Make sure you have implmeted according to your requirement. I have written this script according to my implementation and its working fine for me.

Where in an Eclipse workspace is the list of projects stored?

In Mac OS X, it is under


Maven:Non-resolvable parent POM and 'parent.relativePath' points at wrong local POM

There was conflict in java version. Resolved after using 1.8 for maven.

jQuery checkbox event handling

$('#myform :checkbox').change(function() {
    // this will contain a reference to the checkbox   
    if (this.checked) {
        // the checkbox is now checked 
    } else {
        // the checkbox is now no longer checked

Python - Create list with numbers between 2 values?

While @Jared's answer for incrementing works for 0.5 step size, it fails for other step sizes due to rounding issues:

np.arange(11, 17, 0.1).tolist()
# [11.0,11.1,11.2,11.299999999999999, ...   16.79999999999998, 16.899999999999977]

Instead I needed something like this myself, working not just for 0.5:

# Example 11->16 step 0.5
s = 11
e = 16
step = 0.5
my_list = [round(num, 2) for num in np.linspace(s,e,(e-s)*int(1/step)+1).tolist()]
# [11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5, 15.0, 15.5, 16.0]

# Example 0->1 step 0.1
s = 0
e = 1
step = 0.1
my_list = [round(num, 2) for num in np.linspace(s,e,(e-s)*int(1/step)+1).tolist()]
# [0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0]

What's the difference between Cache-Control: max-age=0 and no-cache?

    When an intermediate cache is forced, by means of a max-age=0 directive, to revalidate 
its own cache entry, and the client has supplied its own validator in the request, the 
supplied validator might differ from the validator currently stored with the cache entry. 
In this case, the cache MAY use either validator in making its own request without 
affecting semantic transparency. 

    However, the choice of validator might affect performance. The best approach is for the 
intermediate cache to use its own validator when making its request. If the server replies 
with 304 (Not Modified), then the cache can return its now validated copy to the client 
with a 200 (OK) response. If the server replies with a new entity and cache validator, 
however, the intermediate cache can compare the returned validator with the one provided in 
the client's request, using the strong comparison function. If the client's validator is 
equal to the origin server's, then the intermediate cache simply returns 304 (Not 
Modified). Otherwise, it returns the new entity with a 200 (OK) response. 

    If a request includes the no-cache directive, it SHOULD NOT include min-fresh, 
max-stale, or max-age. 


Don't accept this as answer - I will have to read it to understand the true usage of it :)

How to check if all inputs are not empty with jQuery

    $('input').each(function() {
            alert('Some fields are empty');
           return false;

How much overhead does SSL impose?

Order of magnitude: zero.

In other words, you won't see your throughput cut in half, or anything like it, when you add TLS. Answers to the "duplicate" question focus heavily on application performance, and how that compares to SSL overhead. This question specifically excludes application processing, and seeks to compare non-SSL to SSL only. While it makes sense to take a global view of performance when optimizing, that is not what this question is asking.

The main overhead of SSL is the handshake. That's where the expensive asymmetric cryptography happens. After negotiation, relatively efficient symmetric ciphers are used. That's why it can be very helpful to enable SSL sessions for your HTTPS service, where many connections are made. For a long-lived connection, this "end-effect" isn't as significant, and sessions aren't as useful.

Here's an interesting anecdote. When Google switched Gmail to use HTTPS, no additional resources were required; no network hardware, no new hosts. It only increased CPU load by about 1%.

What exactly should be set in PYTHONPATH?

You don't have to set either of them. PYTHONPATH can be set to point to additional directories with private libraries in them. If PYTHONHOME is not set, Python defaults to using the directory where python.exe was found, so that dir should be in PATH.

How to set UTF-8 encoding for a PHP file

header('Content-type: text/plain; charset=utf-8');

Android ListView Selector Color

TO ADD: @Christopher's answer does not work on API 7/8 (as per @Jonny's correct comment) IF you are using colours, instead of drawables. (In my testing, using drawables as per Christopher works fine)

Here is the FIX for 2.3 and below when using colours:

As per @Charles Harley, there is a bug in 2.3 and below where filling the list item with a colour causes the colour to flow out over the whole list. His fix is to define a shape drawable containing the colour you want, and to use that instead of the colour.

I suggest looking at this link if you want to just use a colour as selector, and are targeting Android 2 (or at least allow for Android 2).

Disable password authentication for SSH

In file /etc/ssh/sshd_config

# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication no

Uncomment the second line, and, if needed, change yes to no.

Then run

service ssh restart

github: server certificate verification failed

Try to connect to repositroy with url:<user>/<project>.git (http except https)

In your case you should clone like this:

git clone<user>/<project>.git

HTTP Error 404 when running Tomcat from Eclipse

  1. Click on Window > Show view > Server OR right click on the server in "Servers" view, select "Properties".
  2. OR Open the Overview screen for the server by double clicking it.
  3. In the Server locations tab , select "Use Tomcat location".
  4. Save the configurations and restart the Server.

This way Eclipse will take full control over Tomcat, this way you'll also be able to access the default Tomcat homepage with the Tomcat Manager when running from inside Eclipse.

Screenshot is attached here

changing default x range in histogram matplotlib

plt.hist(hmag, 30, range=[6.5, 12.5], facecolor='gray', align='mid')

fileReader.readAsBinaryString to upload files

(Following is a late but complete answer)

FileReader methods support

FileReader.readAsBinaryString() is deprecated. Don't use it! It's no longer in the W3C File API working draft:

void abort();
void readAsArrayBuffer(Blob blob);
void readAsText(Blob blob, optional DOMString encoding);
void readAsDataURL(Blob blob);

NB: Note that File is a kind of extended Blob structure.

Mozilla still implements readAsBinaryString() and describes it in MDN FileApi documentation:

void abort();
void readAsArrayBuffer(in Blob blob); Requires Gecko 7.0
void readAsBinaryString(in Blob blob);
void readAsDataURL(in Blob file);
void readAsText(in Blob blob, [optional] in DOMString encoding);

The reason behind readAsBinaryString() deprecation is in my opinion the following: the standard for JavaScript strings are DOMString which only accept UTF-8 characters, NOT random binary data. So don't use readAsBinaryString(), that's not safe and ECMAScript-compliant at all.

We know that JavaScript strings are not supposed to store binary data but Mozilla in some sort can. That's dangerous in my opinion. Blob and typed arrays (ArrayBuffer and the not-yet-implemented but not necessary StringView) were invented for one purpose: allow the use of pure binary data, without UTF-8 strings restrictions.

XMLHttpRequest upload support

XMLHttpRequest.send() has the following invocations options:

void send();
void send(ArrayBuffer data);
void send(Blob data);
void send(Document data);
void send(DOMString? data);
void send(FormData data);

XMLHttpRequest.sendAsBinary() has the following invocations options:

void sendAsBinary(   in DOMString body );

sendAsBinary() is NOT a standard and may not be supported in Chrome.


So you have several options:

  1. send() the FileReader.result of FileReader.readAsArrayBuffer ( fileObject ). It is more complicated to manipulate (you'll have to make a separate send() for it) but it's the RECOMMENDED APPROACH.
  2. send() the FileReader.result of FileReader.readAsDataURL( fileObject ). It generates useless overhead and compression latency, requires a decompression step on the server-side BUT it's easy to manipulate as a string in Javascript.
  3. Being non-standard and sendAsBinary() the FileReader.result of FileReader.readAsBinaryString( fileObject )

MDN states that:

The best way to send binary content (like in files upload) is using ArrayBuffers or Blobs in conjuncton with the send() method. However, if you want to send a stringifiable raw data, use the sendAsBinary() method instead, or the StringView (Non native) typed arrays superclass.

WebForms UnobtrusiveValidationMode requires a ScriptResourceMapping for jquery

I think this is the best solution for this type error. So please add below line. Also it work my code when I am using MSVS 2015.

<add key="ValidationSettings:UnobtrusiveValidationMode" value="None" />

Enums in Javascript with ES6

If you don't need pure ES6 and can use Typescript, it has a nice enum: