Programs & Examples On #Bisect

ModuleNotFoundError: What does it mean __main__ is not a package?

The problem still not resolved after remove the '.', then it start points the error to my folder. As i added this folder first time then i restarted the PyCharm and it automatically resolved the issue

Style bottom Line in Android

This worked best for me:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="">
    <item android:top="-5dp" android:left="-5dp" android:right="-5dp" android:bottom="0dp">
        <shape android:shape="rectangle">
            <stroke android:width="4dp" android:color="#ff0000"/>

Shows the line on the bottom only. You can easily change with stroke width to size you like and also update the top, left, right on the accordingly.

Find which commit is currently checked out in Git

You can just do:

git rev-parse HEAD

To explain a bit further: git rev-parse is git's basic command for interpreting any of the exotic ways that you can specify the name of a commit and HEAD is a reference to your current commit or branch. (In a git bisect session, it points directly to a commit ("detached HEAD") rather than a branch.)

Alternatively (and easier to remember) would be to just do:

git show

... which defaults to showing the commit that HEAD points to. For a more concise version, you can do:

$ git show --oneline -s
c0235b7 Autorotate uploaded images based on EXIF orientation

Binary search (bisection) in Python

Why not look at the code for bisect_left/right and adapt it to suit your purpose.

like this:

def binary_search(a, x, lo=0, hi=None):
    if hi is None:
        hi = len(a)
    while lo < hi:
        mid = (lo+hi)//2
        midval = a[mid]
        if midval < x:
            lo = mid+1
        elif midval > x: 
            hi = mid
            return mid
    return -1

Strange Characters in database text: Ã, Ã, ¢, â‚ €,

This is surely an encoding problem. You have a different encoding in your database and in your website and this fact is the cause of the problem. Also if you ran that command you have to change the records that are already in your tables to convert those character in UTF-8.

Update: Based on your last comment, the core of the problem is that you have a database and a data source (the CSV file) which use different encoding. Hence you can convert your database in UTF-8 or, at least, when you get the data that are in the CSV, you have to convert them from UTF-8 to latin1.

You can do the convertion following this articles:

Waiting for background processes to finish before exiting script

GNU parallel and xargs

These two tools that can make scripts simpler, and also control the maximum number of threads (thread pool). E.g.:

seq 10 | xargs -P4 -I'{}' echo '{}'


seq 10 | parallel -j4  echo '{}'

See also: how to write a process-pool bash shell

Best way to find the months between two dates

One liner to find a list of datetimes, incremented by month, between two dates.

import datetime
from dateutil.rrule import rrule, MONTHLY

strt_dt =,1,1)
end_dt =,6,1)

dates = [dt for dt in rrule(MONTHLY, dtstart=strt_dt, until=end_dt)]

Java: Calling a super method which calls an overridden method

"this" keyword refers to current class reference. That means, when it is used inside the method, the 'current' class is still SubClass and so, the answer is explained.

Animate background image change with jQuery

I had the same problem, after loads of research and Googling, I found the following solution worked best for me! plenty of trial and error went into this one.



$(document).ready(function() {
                $(this).css({"background-image":"url(<?php bloginfo('template_url') ?>/img/header-boy-hover.jpg)"});


header {
    -webkit-transition:all 1s ease-in;
    -moz-transition:all 1s ease-in;
    -o-transition:all 1s ease-in;
    -ms-transition:all 1s ease-in;
    transition:all 1s ease-in;

font awesome icon in select option

I used this solution and it worked with Font Awesome 5:

What made the difference in my case was to add font-weight: 900;to the class. Keep in mind to 'fa' to the value.

Example of my code:

<select class="text-primary fa-select" name="class_logo" required>
  <option value="fa address-book">&#xf2b9; address-book</option>
  <option value="fa adjust">&#xf042; adjust</option>
  <option value="fa air-freshener">&#xf5d0; air-freshener</option>


.fa-select {
    font-family: 'Lato', 'Font Awesome 5 Free';
    font-weight: 900;

Edit: If you are mixing Solid Icons with Brand Icons in the select, change the CSS as follows:

.fa-select {
    font-family: 'Lato', 'Font Awesome 5 Free', 'Font Awesome 5 Brands';
    font-weight: 900;

file_get_contents("php://input") or $HTTP_RAW_POST_DATA, which one is better to get the body of JSON request?

The usual rules should apply for how you send the request. If the request is to retrieve information (e.g. a partial search 'hint' result, or a new page to be displayed, etc...) you can use GET. If the data being sent is part of a request to change something (update a database, delete a record, etc..) then use POST.

Server-side, there's no reason to use the raw input, unless you want to grab the entire post/get data block in a single go. You can retrieve the specific information you want via the _GET/_POST arrays as usual. AJAX libraries such as MooTools/jQuery will handle the hard part of doing the actual AJAX calls and encoding form data into appropriate formats for you.

SSIS package creating Hresult: 0x80004005 Description: "Login timeout expired" error

The answer here is not clear, so I wanted to add more detail.

Using the link provided above, I performed the following step.

In my XML config manager I changed the "Provider" to SQLOLEDB.1 rather than SQLNCLI.1. This got me past this error.

This information is available at the link the OP posted in the Answer.

The link the got me there:

Can you animate a height change on a UITableViewCell when selected?

Check this method after iOS 7 and later.

- (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath{
    return UITableViewAutomaticDimension;

Improvements have been made to this in iOS 8. We can set it as property of the table view itself.

angular 2 sort and filter

This is my sort. It will do number sort , string sort and date sort .

import { Pipe , PipeTransform  } from "@angular/core";

  name: 'sortPipe'

export class SortPipe implements PipeTransform {

    transform(array: Array<string>, key: string): Array<string> {

        console.log("Entered in pipe*******  "+ key);

        if(key === undefined || key == '' ){
            return array;

        var arr = key.split("-");
        var keyString = arr[0];   // string or column name to sort(name or age or date)
        var sortOrder = arr[1];   // asc or desc order
        var byVal = 1;

        array.sort((a: any, b: any) => {

            if(keyString === 'date' ){

                let left    = Number(new Date(a[keyString]));
                let right   = Number(new Date(b[keyString]));

                return (sortOrder === "asc") ? right - left : left - right;
            else if(keyString === 'name'){

                if(a[keyString] < b[keyString]) {
                    return (sortOrder === "asc" ) ? -1*byVal : 1*byVal;
                } else if (a[keyString] > b[keyString]) {
                    return (sortOrder === "asc" ) ? 1*byVal : -1*byVal;
                } else {
                    return 0;
            else if(keyString === 'age'){
                return (sortOrder === "asc") ? a[keyString] - b[keyString] : b[keyString] - a[keyString];


        return array;



Ignoring directories in Git repositories on Windows

You can create the ".gitignore" file with the contents:


It works for me.

What are good grep tools for Windows?

FINDSTR is fairly powerful, supports regular expressions and has the advantages of being on all Windows machines already.

c:\> FindStr /?

Searches for strings in files.

FINDSTR [/B] [/E] [/L] [/R] [/S] [/I] [/X] [/V] [/N] [/M] [/O] [/P] [/F:file]
        [/C:string] [/G:file] [/D:dir list] [/A:color attributes] [/OFF[LINE]]
        strings [[drive:][path]filename[ ...]]

  /B         Matches pattern if at the beginning of a line.
  /E         Matches pattern if at the end of a line.
  /L         Uses search strings literally.
  /R         Uses search strings as regular expressions.
  /S         Searches for matching files in the current directory and all
  /I         Specifies that the search is not to be case-sensitive.
  /X         Prints lines that match exactly.
  /V         Prints only lines that do not contain a match.
  /N         Prints the line number before each line that matches.
  /M         Prints only the filename if a file contains a match.
  /O         Prints character offset before each matching line.
  /P         Skip files with non-printable characters.
  /OFF[LINE] Do not skip files with offline attribute set.
  /A:attr    Specifies color attribute with two hex digits. See "color /?"
  /F:file    Reads file list from the specified file(/ stands for console).
  /C:string  Uses specified string as a literal search string.
  /G:file    Gets search strings from the specified file(/ stands for console).
  /D:dir     Search a semicolon delimited list of directories
  strings    Text to be searched for.
             Specifies a file or files to search.

Use spaces to separate multiple search strings unless the argument is prefixed
with /C.  For example, 'FINDSTR "hello there" x.y' searches for "hello" or
"there" in file x.y.  'FINDSTR /C:"hello there" x.y' searches for
"hello there" in file x.y.

Regular expression quick reference:
  .        Wildcard: any character
  *        Repeat: zero or more occurances of previous character or class
  ^        Line position: beginning of line
  $        Line position: end of line
  [class]  Character class: any one character in set
  [^class] Inverse class: any one character not in set
  [x-y]    Range: any characters within the specified range
  \x       Escape: literal use of metacharacter x
  \<xyz    Word position: beginning of word
  xyz\>    Word position: end of word

Example usage: findstr text_to_find * or to search recursively findstr /s text_to_find *

Adding class to element using Angular JS

querySelector is not from Angular but it's in document and it's in all DOM elements (expensive). You can use ng-class or inside directive add addClass on the element:

myApp.directive('yourDirective', [function(){
    return {
        restrict: 'A',
        link: function(scope, elem, attrs) {
            // Remove class

Visual Studio Code Search and Replace with Regular Expressions

For beginners, I wanted to add to the accepted answer, because a couple of subtleties were unclear to me:

To find and modify text (not completely replace),

  1. In the "Find" step, you can use regex with "capturing groups," e.g. your search could be la la la (group1) blah blah (group2), using parentheses.

  2. And then in the "Replace" step, you can refer to the capturing groups via $1, $2 etc.

So, for example, in this case we could find the relevant text with just <h1>.+?<\/h1> (no parentheses), but putting in the parentheses <h1>(.+?)<\/h1> allows us to refer to the sub-match in between them as $1 in the replace step. Cool!


  • To turn on Regex in the Find Widget, click the .* icon, or press Cmd/Ctrl Alt R

  • $0 refers to the whole match

  • Finally, the original question states that the replace should happen "within a document," so you can use the "Find Widget" (Cmd or Ctrl + F), which is local to the open document, instead of "Search", which opens a bigger UI and looks across all files in the project.

Using File.listFiles with FileNameExtensionFilter

One-liner in java 8 syntax:

pdfTestDir.listFiles((dir, name) -> name.toLowerCase().endsWith(".txt"));

Function for Factorial in Python

Another way to do it is to use shown below:

def factorial(n):
    if n == 0:
        return 1

How to get root directory of project in core. Directory.GetCurrentDirectory() doesn't seem to work correctly on a mac

If that can be useful to anyone, in a Razor Page cshtml.cs file, here is how to get it: add an IHostEnvironment hostEnvironment parameter to the constructor and it will be injected automatically:

public class IndexModel : PageModel
    private readonly ILogger<IndexModel> _logger;
    private readonly IHostEnvironment _hostEnvironment;

    public IndexModel(ILogger<IndexModel> logger, IHostEnvironment hostEnvironment)
        _logger = logger;
        _hostEnvironment = hostEnvironment; // has ContentRootPath property

    public void OnGet()


PS: IHostEnvironment is in Microsoft.Extensions.Hosting namespace, in Microsoft.Extensions.Hosting.Abstractions.dll ... what a mess!

Ignore files that have already been committed to a Git repository

Thanks to your answer, I was able to write this little one-liner to improve it. I ran it on my .gitignore and repo, and had no issues, but if anybody sees any glaring problems, please comment. This should git rm -r --cached from .gitignore:

cat $(git rev-parse --show-toplevel)/.gitIgnore | sed "s/\/$//" | grep -v "^#" | xargs -L 1 -I {} find $(git rev-parse --show-toplevel) -name "{}" | xargs -L 1 git rm -r --cached

Note that you'll get a lot of fatal: pathspec '<pathspec>' did not match any files. That's just for the files which haven't been modified.

How do I get a list of installed CPAN modules?

Here a script which would do the trick:

use ExtUtils::Installed;

my $inst = ExtUtils::Installed->new();
my @modules = $inst->modules();
foreach $module (@modules){
       print $module ." - ". $inst->version($module). "\n";

=head1 ABOUT

This scripts lists installed cpan modules using the ExtUtils modules

=head1 FORMAT

Prints each module in the following format
<name> - <version>


How to iterate through a list of dictionaries in Jinja template?


parent_list = [{'A': 'val1', 'B': 'val2'}, {'C': 'val3', 'D': 'val4'}]

in Jinja2 iteration:

{% for dict_item in parent_list %}
   {% for key, value in dict_item.items() %}
      <h1>Key: {{key}}</h1>
      <h2>Value: {{value}}</h2>
   {% endfor %}
{% endfor %}


Make sure you have the list of dict items. If you get UnicodeError may be the value inside the dict contains unicode format. That issue can be solved in your If the dict is unicode object, you have to encode into utf-8.

Android: Scale a Drawable or background image?

Use image as background sized to layout:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android=""
    android:layout_height="wrap_content" >

        android:src="@drawable/img_dsh" />

        android:orientation="vertical" >



Angular CLI SASS options

I noticed a very anoying gotcha in moving to scss files!!! One MUST move from a simple: styleUrls: ['app.component.scss'] to styleUrls: ['./app.component.scss'] (add ./) in app.component.ts

Which ng does when you generate a new project, but seemingly not when the default project is created. If you see resolve errors during ng build, check for this issue. It only took me ~ 1 hour.

How to delete a localStorage item when the browser window/tab is closed?

There are five methods to choose from:

  • setItem(): Add key and value to localStorage
  • getItem(): Retrieve a value by the key from localStorage
  • removeItem(): Remove an item by key from localStorage
  • clear(): Clear all localStorage
  • key(): Passed a number to retrieve nth key of a localStorage

You can use clear(), this method when invoked clears the entire storage of all records for that domain. It does not receive any parameters.


Messagebox with input field

You can do it by making form and displaying it using ShowDialogBox....

Form.ShowDialog Method - Shows the form as a modal dialog box.


public void ShowMyDialogBox()
   Form2 testDialog = new Form2();

   // Show testDialog as a modal dialog and determine if DialogResult = OK.
   if (testDialog.ShowDialog(this) == DialogResult.OK)
      // Read the contents of testDialog's TextBox.
      this.txtResult.Text = testDialog.TextBox1.Text;
      this.txtResult.Text = "Cancelled";

Cannot find the object because it does not exist or you do not have permissions. Error in SQL Server

In my case I was running under a different user than the one I was expecting.

I had 'DRIVER={SQL Server};SERVER=...;DATABASE=...;Trusted_Connection=false;User Id=XXX;Password=YYY' as the connection string I passed to pypyodbc.connect(), but the connection was still using the credentials of the Windows user that ran the script (I verified this using the SQL Server Profiler and by trying an invalid uid/password combination - which didn't result in an expected error).

I decided not to dig into this further, since switching to this better way of connecting fixed the issue:

conn = pypyodbc.connect(driver='{SQL Server}', server='servername', database='dbname', uid='userName', pwd='Password')

How to read a line from a text file in c/c++?

In c, you could use fopen, and getch. Usually, if you can't be exactly sure of the length of the longest line, you could allocate a large buffer (e.g. 8kb) and almost be guaranteed of getting all lines.

If there's a chance you may have really really long lines and you have to process line by line, you could malloc a resonable buffer, and use realloc to double it's size each time you get close to filling it.

#include <stdio.h>
#include <stdlib.h>

void handle_line(char *line) {
  printf("%s", line);

int main(int argc, char *argv[]) {
    int size = 1024, pos;
    int c;
    char *buffer = (char *)malloc(size);

    FILE *f = fopen("myfile.txt", "r");
    if(f) {
      do { // read all lines in file
        pos = 0;
        do{ // read one line
          c = fgetc(f);
          if(c != EOF) buffer[pos++] = (char)c;
          if(pos >= size - 1) { // increase buffer length - leave room for 0
            size *=2;
            buffer = (char*)realloc(buffer, size);
        }while(c != EOF && c != '\n');
        buffer[pos] = 0;
        // line is now in buffer
      } while(c != EOF); 
    return 0;

LINQ to SQL: Multiple joins ON multiple Columns. Is this possible?

I would like to give another example in which multiple (3) joins are used.

 DataClasses1DataContext ctx = new DataClasses1DataContext();

        var Owners = ctx.OwnerMasters;
        var Category = ctx.CategoryMasters;
        var Status = ctx.StatusMasters;
        var Tasks = ctx.TaskMasters;

        var xyz = from t in Tasks
                  join c in Category
                  on t.TaskCategory equals c.CategoryID
                  join s in Status
                  on t.TaskStatus equals s.StatusID
                  join o in Owners
                  on t.TaskOwner equals o.OwnerID
                  select new

How to update the value stored in Dictionary in C#?

Here is a way to update by an index much like foo[x] = 9 where x is a key and 9 is the value

var views = new Dictionary<string, bool>();

foreach (var g in grantMasks)
    string m = g.ToString();
    for (int i = 0; i <= m.Length; i++)
        views[views.ElementAt(i).Key] = m[i].Equals('1') ? true : false;

How to remove all leading zeroes in a string

Similar to another suggestion, except will not obliterate actual zero:

if (ltrim($str, '0') != '') {
    $str = ltrim($str, '0');
} else {
    $str = '0';

Or as was suggested (as of PHP 5.3), shorthand ternary operator can be used:

$str = ltrim($str, '0') ?: '0'; 

How to do a timer in Angular 5

You can simply use setInterval to create such timer in Angular, Use this Code for timer -

timeLeft: number = 60;

startTimer() {
    this.interval = setInterval(() => {
      if(this.timeLeft > 0) {
      } else {
        this.timeLeft = 60;

  pauseTimer() {

<button (click)='startTimer()'>Start Timer</button>
<button (click)='pauseTimer()'>Pause</button>

<p>{{timeLeft}} Seconds Left....</p>

Working Example

Another way using Observable timer like below -

import { timer } from 'rxjs';

observableTimer() {
    const source = timer(1000, 2000);
    const abc = source.subscribe(val => {
      console.log(val, '-');
      this.subscribeTimer = this.timeLeft - val;

<p (click)="observableTimer()">Start Observable timer</p> {{subscribeTimer}}

Working Example

For more information read here

How to insert date values into table

I simply wrote an embedded SQL program to write a new record with date fields. It was by far best and shortest without any errors I was able to reach my requirement.

w_dob = %char(%date(*date));      
exec sql insert into Tablename (ID_Number     , 
                             AmendmentNo   , 
                             OverrideDate  , 
                             Operator      , 
                             Text_ID       , 
                             Policy_Number , 
                             Override      , 
                             CREATE_USER   ) 
                values ( '801010',    
                            ' ',         

How to add column to numpy array

The easiest solution is to use numpy.insert().

The Advantage of np.insert() over np.append is that you can insert the new columns into custom indices.

import numpy as np

X = np.arange(20).reshape(10,2)

X = np.insert(X, [0,2], np.random.rand(X.shape[0]*2).reshape(-1,2)*10, axis=1)

SQL Server 2012 can't start because of a login failure

Short answer:
install Remote Server Administration tools on your SQL Server (it's an optional feature of Windows Server), reboot, then run SQL Server configuration manager, access the service settings for each of the services whose logon account starts with "NT Service...", clear out the password fields and restart the service. Under the covers, SQL Server Config manager will assign these virtual accounts the Log On as a Service right, and you'll be on your way.


There is a catch-22 between default settings for a windows domain and default install of SQL Server 2012.

As mentioned above, default Windows domain setup will indeed prevent you from defining the "log on as a service" right via Group Policy Edit at the local machine (via GUI at least; if you install Powershell ActiveDirectory module (via Remote Server Administration tools download) you can do it by scripting.

And, by default, SQL Server 2012 setup runs services in "virtual accounts" (NT Service\ prefix, e.g, NT Service\MSSQLServer. These are like local machine accounts, not domain accounts, but you still can't assign them log on as service rights if your server is joined to a domain. SQL Server setup attempts to assign the right at install, and the SQL Server Config Management tool likewise attempts to assign the right when you change logon account.

And the beautiful catch-22 is this: SQL Server tools depend on (some component of) RSAT to assign the logon as service right. If you don't happen to have RSAT installed on your member server, SQL Server Config Manager fails silently trying to apply the setting (despite all the gaudy pre-installation verification it runs) and you end up with services that won't start.

The one hint of this requirement that I was able to find in the blizzard of SQL Server and Virtual Account doc was this:, search for RSAT.

How to make a JFrame button open another JFrame class in Netbeans?


You can either use setVisible(false) or dispose() method to disappear current form.

Mean per group in a data.frame

A third great alternative is using the package data.table, which also has the class data.frame, but operations like you are looking for are computed much faster.

mydt <- structure(list(Name = c("Aira", "Aira", "Aira", "Ben", "Ben", "Ben", "Cat", "Cat", "Cat"), Month = c(1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L), Rate1 = c(15.6396600443877, 2.15649279424609, 6.24692918928743, 2.37658797276116, 34.7500663272292, 3.28750138697048, 29.3265553981065, 17.9821839334431, 10.8639802575958), Rate2 = c(17.1680489538369, 5.84231656330206, 8.54330866437461, 5.88415184986176, 3.02064294862551, 17.2053351400752, 16.9552950199166, 2.56058000170089, 15.7496228048122)), .Names = c("Name", "Month", "Rate1", "Rate2"), row.names = c(NA, -9L), class = c("data.table", "data.frame"))

Now to take the mean of Rate1 and Rate2 for all 3 months, for each person (Name): First, decide which columns you want to take the mean of

colstoavg <- names(mydt)[3:4]

Now we use lapply to take the mean over the columns we want to avg (colstoavg)

mydt.mean <- mydt[,lapply(.SD,mean,na.rm=TRUE),by=Name,.SDcols=colstoavg]

   Name     Rate1     Rate2
1: Aira  8.014361 10.517891
2:  Ben 13.471385  8.703377
3:  Cat 19.390907 11.755166

How do I print to the debug output window in a Win32 app?

To print to the real console, you need to make it visible by using the linker flag /SUBSYSTEM:CONSOLE. The extra console window is annoying, but for debugging purposes it's very valuable.

OutputDebugString prints to the debugger output when running inside the debugger.

ASP.Net MVC Redirect To A Different View

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

Do I use <img>, <object>, or <embed> for SVG files?

Found one solution with pure CSS and without double image downloading. It is not beautiful as I want, but it works.

<!DOCTYPE html>
    <title>HTML5 SVG demo</title>
    <style type="text/css">
     .nicolas_cage {
         background: url('nicolas_cage.jpg');
         width: 20px;
         height: 15px;
     .fallback {
<svg xmlns="" width="0" height="0">
        .fallback { background: none; background-image: none; display: none; }

<!-- inline svg -->
<svg xmlns="" width="40" height="40">
     <circle cx="20" cy="20" r="18" stroke="grey" stroke-width="2" fill="#99FF66" />
         <div class="nicolas_cage fallback"></div>
<!-- external svg -->
    <object type="image/svg+xml" data="circle_orange.svg">
        <div class="nicolas_cage fallback"></div>

The idea is to insert special SVG with fallback style.

More details and testing process you can find in my blog.

Why an interface can not implement another interface?

implements means implementation, when interface is meant to declare just to provide interface not for implementation.

A 100% abstract class is functionally equivalent to an interface but it can also have implementation if you wish (in this case it won't remain 100% abstract), so from the JVM's perspective they are different things.

Also the member variable in a 100% abstract class can have any access qualifier, where in an interface they are implicitly public static final.

post ajax data to PHP and return data

For the JS, try

data: {id: the_id}
success: function(data) {
        alert('the server returned ' + data;


$the_id = intval($_POST['id']);

in PHP

What's the best way to add a drop shadow to my UIView

On viewWillLayoutSubviews:

override func viewWillLayoutSubviews() {
    sampleView.layer.masksToBounds =  false
    sampleView.layer.shadowColor = UIColor.darkGrayColor().CGColor;
    sampleView.layer.shadowOffset = CGSizeMake(2.0, 2.0)
    sampleView.layer.shadowOpacity = 1.0

Using Extension of UIView:

extension UIView {

    func addDropShadowToView(targetView:UIView? ){
        targetView!.layer.masksToBounds =  false
        targetView!.layer.shadowColor = UIColor.darkGrayColor().CGColor;
        targetView!.layer.shadowOffset = CGSizeMake(2.0, 2.0)
        targetView!.layer.shadowOpacity = 1.0



Import Excel to Datagridview

try the following program

using System;
using System.Data;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication1
public partial class Form1 : Form
    public Form1()

    private void button1_Click(object sender, EventArgs e)
        System.Data.OleDb.OleDbConnection MyConnection;
        System.Data.DataSet DtSet;
        System.Data.OleDb.OleDbDataAdapter MyCommand;
        MyConnection = new System.Data.OleDb.OleDbConnection(@"provider=Microsoft.Jet.OLEDB.4.0;Data Source='c:\';Extended Properties=Excel 8.0;");
        MyCommand = new System.Data.OleDb.OleDbDataAdapter("select * from [Sheet1$]", MyConnection);
        MyCommand.TableMappings.Add("Table", "");
        DtSet = new System.Data.DataSet();
        dataGridView1.DataSource = DtSet.Tables[0];

Java random numbers using a seed

You shouldn't be creating a new Random in method scope. Make it a class member:

public class Foo {
   private Random random 

   public Foo() {

   public Foo(long seed) {
       this.random = new Random(seed);

   public synchronized double getNext() {
        return generator.nextDouble();

This is only an example. I don't think wrapping Random this way adds any value. Put it in a class of yours that is using it.

Write to file, but overwrite it if it exists

Just noting that if you wish to redirect both stderr and stdout to a file while you have noclobber set (i.e. set -o noclobber), you can use the code:

cmd >| file.txt 2>&1

More information about this can be seen at

Also this answer's @TuBui's question on the answer @BrDaHa provided above at Aug 9 '18 at 9:34.

WPF binding to Listbox selectedItem

Inside the DataTemplate you're working in the context of a Rule, that's why you cannot bind to SelectedRule.Name -- there is no such property on a Rule. To bind to the original data context (which is your ViewModel) you can write:

<TextBlock Text="{Binding ElementName=lbRules, Path=DataContext.SelectedRule.Name}" />

UPDATE: regarding the SelectedItem property binding, it looks perfectly valid, I tried the same on my machine and it works fine. Here is my full test app:


<Window x:Class="TestWpfApplication.ListBoxSelectedItem"
    Title="ListBoxSelectedItem" Height="300" Width="300"
    <ListBox ItemsSource="{Binding Path=Rules}" SelectedItem="{Binding Path=SelectedRule, Mode=TwoWay}">
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="Name:" />
                    <TextBox Text="{Binding Name}"/>

Code behind:

namespace TestWpfApplication
    /// <summary>
    /// Interaction logic for ListBoxSelectedItem.xaml
    /// </summary>
    public partial class ListBoxSelectedItem : Window
        public ListBoxSelectedItem()

    public class Rule
        public string Name { get; set; }

    public class ListBoxSelectedItemViewModel
        public ListBoxSelectedItemViewModel()
            Rules = new ObservableCollection<Rule>()
                new Rule() { Name = "Rule 1"},
                new Rule() { Name = "Rule 2"},
                new Rule() { Name = "Rule 3"},

        public ObservableCollection<Rule> Rules { get; private set; }

        private Rule selectedRule;
        public Rule SelectedRule
            get { return selectedRule; }
                selectedRule = value;

How to tell which disk Windows Used to Boot

That depends on your definition of which disk drive Windows used to boot. I can think of 3 different answers on a standard BIOS system (who knows what an EFI system does):

  1. The drive that contains the active MBR
  2. The active partition, with NTLDR (the system partition)
  3. The partition with Windows on it (the boot partition)

2 and 3 should be easy to find - I'm not so sure about 1. Though you can raw disk read to find an MBR, that doesn't mean it's the BIOS boot device this time or even next time (you could have multiple disks with MBRs).

You really can't even be sure that the PC was started from a hard drive - it's perfectly possible to boot Windows from a floppy. In that case, both 1 and 2 would technically be a floppy disk, though 3 would remain C:\Windows.

You might need to be a bit more specific in your requirements or goals.

__init__ and arguments in Python

The fact that your method does not use the self argument (which is a reference to the instance that the method is attached to) doesn't mean you can leave it out. It always has to be there, because Python is always going to try to pass it in.

jQuery Find and List all LI elements within a UL within a specific DIV

Are you thinking about something like this?

$('ul li').each(function(i)
   $(this).attr('rel'); // This is your rel value

Hiding and Showing TabPages in tabControl

TabPanel1.Visible = true; // Show Tabpage 1
TabPanel1.Visible = false; //Hide Tabpage 1

How to change collation of database, table, column?

You can change the CHARSET and COLLATION of all your tables through PHP script as follows. I like the answer of hkasera but the problem with it is that the query runs twice on each table. This code is almost the same except using MySqli instead of mysql and prevention of double querying. If I could vote up, I would have voted hkasera's answer up.

$conn1=new MySQLi("localhost","user","password","database");
    echo mysqli_connect_error();
$res=$conn1->query("show tables") or die($conn1->error);
    $conn1->query("ALTER TABLE $tables[0] CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci") or die($conn1->error);
echo "The collation of your database has been successfully changed!";



Should I use 'has_key()' or 'in' on Python dicts?

has_key is a dictionary method, but in will work on any collection, and even when __contains__ is missing, in will use any other method to iterate the collection to find out.

Can't change z-index with JQuery

zIndex is part of javaScript notation.(camelCase)
but jQuery.css uses same as CSS syntax.
so it is z-index.

you forgot .css("attr","value"). use ' or " in both, attr and val. so, .css("z-index","3000");

How to print something when running Puppet client?

If, like me, you don't have access to the puppet master and need to print debug logs to inspect variables on your puppet client machine, you can try writing to a file from your puppet code itself:

file { '/tmp/puppet_debug.log':
  content => inline_template('<%= @variable_x.to_s %>'),

SVN: Folder already under version control but not comitting?

I had a similar-looking problem after adding a directory tree which contained .svn directories (because it was an svn:external in its source environment): svn status told me "?", but when trying to add it, it was "already under version control".

Since no other versioned directories were present, I did

find . -mindepth 2 -name '.svn' -exec rm -rf '{}' \;

to remove the wrong .svn directories; after doing this, I was able to add the new directory.


  • If other versioned directories are contained, the find expression must be changed to be more specific
  • If unsure, first omit the "-exec ..." part to see what would be deleted

How to add buttons at top of map fragment API v2 layout

Maybe a simpler solution is to set an overlay in front of your map using FrameLayout or RelativeLayout and treating them as regular buttons in your activity. You should declare your layers in back to front order, e.g., map before buttons. I modified your layout, simplified it a little bit. Try the following layout and see if it works for you:

<FrameLayout xmlns:android=""
    tools:context=".MapActivity" >

    <fragment xmlns:map=""

        android:padding="4dp" >

            android:textColor="@color/textcolor_radiobutton" />
            android:background="#aaa" />

            android:textColor="@color/textcolor_radiobutton" />

            android:background="#aaa" />

            android:textColor="@color/textcolor_radiobutton" />
            android:background="#aaa" />

            android:textColor="@color/textcolor_radiobutton" />

Android Room - simple select query - Cannot access database on the main thread

An elegant RxJava/Kotlin solution is to use Completable.fromCallable, which will give you an Observable which does not return a value, but can observed and subscribed on a different thread.

public Completable insert(Event event) {
    return Completable.fromCallable(new Callable<Void>() {
        public Void call() throws Exception {
            return database.eventDao().insert(event)

Or in Kotlin:

fun insert(event: Event) : Completable = Completable.fromCallable {

You can the observe and subscribe as you would usually:


Maven: add a dependency to a jar by relative path

I've previously written about a pattern for doing this.

It is very similar to the solution proposed by Pascal, though it moves all such dependencies into a dedicated repository module so that you don't have to repeat it everywhere the dependency is used if it is a multi-module build.

Splitting words into letters in Java

You need to use split("");.

That will split it by every character.

However I think it would be better to iterate over a String's characters like so:

for (int i = 0;i < str.length(); i++){

It is unnecessary to create another copy of your String in a different form.

How to compare two java objects

You need to implement the equals() method in your MyClass.

The reason that == didn't work is this is checking that they refer to the same instance. Since you did new for each, each one is a different instance.

The reason that equals() didn't work is because you didn't implement it yourself yet. I believe it's default behavior is the same thing as ==.

Note that you should also implement hashcode() if you're going to implement equals() because a lot of java.util Collections expect that.

Add image in title bar

Add this in the head section of your html

<link rel="icon" type="image/gif/png" href="mouse_select_left.png">

git: undo all working dir changes including new files

git reset --hard # removes staged and working directory changes

## !! be very careful with these !!
## you may end up deleting what you don't want to
## read comments and manual.
git clean -f -d # remove untracked
git clean -f -x -d # CAUTION: as above but removes ignored files like config.
git clean -fxd :/ # CAUTION: as above, but cleans untracked and ignored files through the entire repo (without :/, the operation affects only the current directory)

To see what will be deleted before-hand, without actually deleting it, use the -n flag (this is basically a test-run). When you are ready to actually delete, then remove the -n flag:

git clean -nfd

How to create a numeric vector of zero length in R

Suppose you want to create a vector x whose length is zero. Now let v be any vector.

> v<-c(4,7,8)
> v
[1] 4 7 8
> x<-v[0]
> length(x)
[1] 0

What is the difference between parseInt() and Number()?

I found two links of performance compare among several ways of converting string to int.

str << 0

Vertical Tabs with JQuery?

I've created a vertical menu and tabs changing in the middle of the page. I changed two words on the code source and I set apart two different divs


<div class="arrowgreen">
  <ul class="tabNavigation"> 
    <li> <a href="#first" title="Home">Tab 1</a></li>
    <li> <a href="#secund" title="Home">Tab 2</a></li>


<div class="pages">
  <div id="first">
  <div id="secund">

the code works with the div apart

$(function () {
    var tabContainers = $('div.pages > div');

    $('div.arrowgreen ul.tabNavigation a').click(function () {

        $('div.arrowgreen ul.tabNavigation a').removeClass('selected');

        return false;

TypeError: can't pickle _thread.lock objects

You need to change from queue import Queue to from multiprocessing import Queue.

The root reason is the former Queue is designed for threading module Queue while the latter is for multiprocessing.Process module.

For details, you can read some source code or contact me!

How to change scroll bar position with CSS?

Here is another way, by rotating element with the scrollbar for 180deg, wrapping it's content into another element, and rotating that wrapper for -180deg. Check the snippet below

div {_x000D_
  display: inline-block;_x000D_
  width: 100px;_x000D_
  height: 100px;_x000D_
  border: 2px solid black;_x000D_
  margin: 15px;_x000D_
#vertical {_x000D_
  direction: rtl;_x000D_
  overflow-y: scroll;_x000D_
  overflow-x: hidden;_x000D_
  background: gold;_x000D_
#vertical p {_x000D_
  direction: ltr;_x000D_
  margin-bottom: 0;_x000D_
#horizontal {_x000D_
  direction: rtl;_x000D_
  transform: rotate(180deg);_x000D_
  overflow-y: hidden;_x000D_
  overflow-x: scroll;_x000D_
  background: tomato;_x000D_
  padding-top: 30px;_x000D_
#horizontal span {_x000D_
  direction: ltr;_x000D_
  display: inline-block;_x000D_
  transform: rotate(-180deg);_x000D_
<script src=""></script>_x000D_
<div id=vertical>_x000D_
<div id=horizontal><span> content_content_content_content_content_content_content_content_content_content_content_content_content_content</span>_x000D_

Setting font on NSAttributedString on UITextView disregards line spacing

You can use this example and change it's implementation like this:

[self enumerateAttribute:NSParagraphStyleAttributeName
                 inRange:NSMakeRange(0, self.length)
              usingBlock:^(id  _Nullable value, NSRange range, BOOL * _Nonnull stop) {
                  NSMutableParagraphStyle *paragraphStyle = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];

                  //add your specific settings for paragraph

                  [self removeAttribute:NSParagraphStyleAttributeName range:range];
                  [self addAttribute:NSParagraphStyleAttributeName value:paragraphStyle range:range];

Create the perfect JPA entity

My 2 cents addition to the answers here are:

  1. With reference to Field or Property access (away from performance considerations) both are legitimately accessed by means of getters and setters, thus, my model logic can set/get them in the same manner. The difference comes to play when the persistence runtime provider (Hibernate, EclipseLink or else) needs to persist/set some record in Table A which has a foreign key referring to some column in Table B. In case of a Property access type, the persistence runtime system uses my coded setter method to assign the cell in Table B column a new value. In case of a Field access type, the persistence runtime system sets the cell in Table B column directly. This difference is not of importance in the context of a uni-directional relationship, yet it is a MUST to use my own coded setter method (Property access type) for a bi-directional relationship provided the setter method is well designed to account for consistency. Consistency is a critical issue for bi-directional relationships refer to this link for a simple example for a well-designed setter.

  2. With reference to Equals/hashCode: It is impossible to use the Eclipse auto-generated Equals/hashCode methods for entities participating in a bi-directional relationship, otherwise they will have a circular reference resulting in a stackoverflow Exception. Once you try a bidirectional relationship (say OneToOne) and auto-generate Equals() or hashCode() or even toString() you will get caught in this stackoverflow exception.

ggplot2 legend to bottom and horizontal

If you want to move the position of the legend please use the following code:

library(reshape2) # for melt
df <- melt(outer(1:4, 1:4), varnames = c("X1", "X2"))
p1 <- ggplot(df, aes(X1, X2)) + geom_tile(aes(fill = value))
p1 + scale_fill_continuous(guide = guide_legend()) +

This should give you the desired result. Legend at bottom

Modifying local variable from inside lambda

This is fairly close to an XY problem. That is, the question being asked is essentially how to mutate a captured local variable from a lambda. But the actual task at hand is how to number the elements of a list.

In my experience, upward of 80% of the time there is a question of how to mutate a captured local from within a lambda, there's a better way to proceed. Usually this involves reduction, but in this case the technique of running a stream over the list indexes applies well:

IntStream.range(0, list.size())
         .forEach(i -> list.get(i).setOrdinal(i));

How to write a comment in a Razor view?

This comment syntax should work for you:

@* enter comments here *@

Animation CSS3: display + opacity

There is another good method to get this done by using pointer-events:

.child {
    opacity: 0;
    pointer-events: none;

    -webkit-transition: opacity 0.5s ease-in-out;
    -moz-transition: opacity 0.5s ease-in-out;
    transition: opacity 0.5s ease-in-out;

.parent:hover .child {
    opacity: 0.9;
    pointer-events: all;

Unfortunately, this is not supported in IE10 and below.

Sending a notification from a service in Android

Both Activity and Service actually extend Context so you can simply use this as your Context within your Service.

NotificationManager notificationManager =
    (NotificationManager) getSystemService(Service.NOTIFICATION_SERVICE);
Notification notification = new Notification(/* your notification */);
PendingIntent pendingIntent = /* your intent */;
notification.setLatestEventInfo(this, /* your content */, pendingIntent);
notificationManager.notify(/* id */, notification);

Run jar file in command prompt

Try this

java -jar <jar-file-name>.jar

Dynamically Changing log4j log level

I have used this method with success to reduce the verbosity of the "org.apache.http" logs:

ch.qos.logback.classic.Logger logger = (ch.qos.logback.classic.Logger) LoggerFactory.getLogger("org.apache.http");

How to print in C

try this:

printf("%d", addNumber(a,b))

Here's the documentation for printf.

jQuery if div contains this text, replace that part of the text

If it's possible, you could wrap the word(s) you want to replace in a span tag, like so:

<div class="text_div">
    This div <span>contains</span> some text.

You can then easily change its contents with jQuery:

$('.text_div > span').text('hello everyone');

If you can't wrap it in a span tag, you could use regular expressions.

Linking a qtDesigner .ui file to python/pyqt?

Combining Max's answer and Shriramana Sharma's mailing list post, I built a small working example for loading a mywindow.ui file containing a QMainWindow (so just choose to create a Main Window in Qt Designer's File-New dialog).

This is the code that loads it:

import sys
from PyQt4 import QtGui, uic

class MyWindow(QtGui.QMainWindow):
    def __init__(self):
        super(MyWindow, self).__init__()
        uic.loadUi('mywindow.ui', self)

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    window = MyWindow()

Row count with PDO

function count_x($connect) {  
 $query = "  SELECT * FROM tbl WHERE id = '0' ";  
 $statement = $connect->prepare($query);  $statement->execute();  
 $total_rows = $statement->rowCount();  
 return $total_rows; 

How can I delete one element from an array by value

I improved Niels's solution

class Array          
  def except(*values)
    self - values

Now you can use

[1, 2, 3, 4].except(3, 4) # return [1, 2]
[1, 2, 3, 4].except(4)    # return [1, 2, 3]

How do synchronized static methods work in Java and can I use it for loading Hibernate entities?

Static methods use the class as the object for locking, which is Utils.class for your example. So yes, it is OK.

PHP function overloading

Sadly there is no overload in PHP as it is done in C#. But i have a little trick. I declare arguments with default null values and check them in a function. That way my function can do different things depending on arguments. Below is simple example:

public function query($queryString, $class = null) //second arg. is optional
    $query = $this->dbLink->prepare($queryString);

    //if there is second argument method does different thing
    if (!is_null($class)) { 
        $query->setFetchMode(PDO::FETCH_CLASS, $class);

    return $query->fetchAll();

//This loads rows in to array of class
$Result = $this->query($queryString, "SomeClass");
//This loads rows as standard arrays
$Result = $this->query($queryString);

How to repeat a string a variable number of times in C++?

You should write your own stream manipulator

cout << multi(5) << "whatever" << "lolcat";

How to add text inside the doughnut chart using Chart.js?

You have to modify the code like: in chart.Doughnut.defaults

labelFontFamily : "Arial",
labelFontStyle : "normal",
labelFontSize : 24,
labelFontColor : "#666"

and then in function drawPieSegments

ctx.fillText(data[0].value + "%", width/2 - 20, width/2, 200);

See this pull:

here is a fiddle implementing the same.

Error #2032: Stream Error

Just to clarify my comment (it's illegible in a single line)

I think the best answer is the comment by Mike Chambers in this link ( by Hunter McMillen.

A note from Mike Chambers:

If you run into this using URLLoader, listen for the:

and in AIR :

It should give you some more information (such as the status code being returned from the server). + Node.js Cross-Origin Request Blocked

Take a look at this: Complete Example


let exp = require('express');
let app = exp();

//UPDATE: this is seems to be deprecated
//let io = require('').listen(app.listen(9009));
//New Syntax:
const io = require('')(app.listen(9009));

app.all('/', function (request, response, next) {
    response.header("Access-Control-Allow-Origin", "*");
    response.header("Access-Control-Allow-Headers", "X-Requested-With");


<script src=""></script>
    var socket = io("", {
        "force new connection": true,
        "reconnectionAttempts": "Infinity", 
        "timeout": 10001, 
        "transports": ["websocket"]

I remember this from the combination of stackoverflow answers many days ago; but I could not find the main links to mention them

How to save SELECT sql query results in an array in C#

Instead of any Array you can load your data in DataTable like:

using System.Data;

DataTable dt = new DataTable();
using (var con = new SqlConnection("Data Source=local;Initial Catalog=Test;Integrated Security=True"))
    using (var command = new SqlCommand("SELECT col1,col2" +
        using (SqlDataReader dr = command.ExecuteReader())

You can also use SqlDataAdapater to fill your DataTable like

SqlDataAdapter da = new SqlDataAdapter(command);

Later you can iterate each row and compare like:

foreach (DataRow dr in dt.Rows)
    if (dr.Field<string>("col1") == "yourvalue") //your condition

ImportError: No module named _ssl

Since --with-ssl is not recognized anymore I just installed the libssl-dev. For debian based systems:

sudo apt-get install libssl-dev 

For CentOS and RHEL

sudo yum install openssl-devel

To restart the make first clean up by:

make clean

Then start again and execute the following commands one after the other:

make test
make install

For further information on OpenSSL visit the Ubuntu Help Page on OpenSSL.

Convert a String In C++ To Upper Case

You can simply use this in C++17

for(auto i : str) putchar(toupper(i));

Get Image Height and Width as integer values?

getimagesize('image.jpg') function works only if allow_url_fopen is set to 1 or On inside php.ini file on the server, if it is not enabled, one should use ini_set('allow_url_fopen',1); on top of the file where getimagesize() function is used.

How to make an Asynchronous Method return a value?

There are a few ways of doing that... the simplest is to have the async method also do the follow-on operation. Another popular approach is to pass in a callback, i.e.

void RunFooAsync(..., Action<bool> callback) {
     // do some stuff
     bool result = ...

     if(callback != null) callback(result);

Another approach would be to raise an event (with the result in the event-args data) when the async operation is complete.

Also, if you are using the TPL, you can use ContinueWith:

Task<bool> outerTask = ...;
outerTask.ContinueWith(task =>
    bool result = task.Result;
    // do something with that

cannot load such file -- bundler/setup (LoadError)

I got this error in a fresh Rails app with bundle correctly installed. Commenting out the spring gem in Gemfile resolved the problem.

Golang read request body

Inspecting and mocking request body

When you first read the body, you have to store it so once you're done with it, you can set a new io.ReadCloser as the request body constructed from the original data. So when you advance in the chain, the next handler can read the same body.

One option is to read the whole body using ioutil.ReadAll(), which gives you the body as a byte slice.

You may use bytes.NewBuffer() to obtain an io.Reader from a byte slice.

The last missing piece is to make the io.Reader an io.ReadCloser, because bytes.Buffer does not have a Close() method. For this you may use ioutil.NopCloser() which wraps an io.Reader, and returns an io.ReadCloser, whose added Close() method will be a no-op (does nothing).

Note that you may even modify the contents of the byte slice you use to create the "new" body. You have full control over it.

Care must be taken though, as there might be other HTTP fields like content-length and checksums which may become invalid if you modify only the data. If subsequent handlers check those, you would also need to modify those too!

Inspecting / modifying response body

If you also want to read the response body, then you have to wrap the http.ResponseWriter you get, and pass the wrapper on the chain. This wrapper may cache the data sent out, which you can inspect either after, on on-the-fly (as the subsequent handlers write to it).

Here's a simple ResponseWriter wrapper, which just caches the data, so it'll be available after the subsequent handler returns:

type MyResponseWriter struct {
    buf *bytes.Buffer

func (mrw *MyResponseWriter) Write(p []byte) (int, error) {
    return mrw.buf.Write(p)

Note that MyResponseWriter.Write() just writes the data to a buffer. You may also choose to inspect it on-the-fly (in the Write() method) and write the data immediately to the wrapped / embedded ResponseWriter. You may even modify the data. You have full control.

Care must be taken again though, as the subsequent handlers may also send HTTP response headers related to the response data –such as length or checksums– which may also become invalid if you alter the response data.

Full example

Putting the pieces together, here's a full working example:

func loginmw(handler http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        body, err := ioutil.ReadAll(r.Body)
        if err != nil {
            log.Printf("Error reading body: %v", err)
            http.Error(w, "can't read body", http.StatusBadRequest)

        // Work / inspect body. You may even modify it!

        // And now set a new body, which will simulate the same data we read:
        r.Body = ioutil.NopCloser(bytes.NewBuffer(body))

        // Create a response wrapper:
        mrw := &MyResponseWriter{
            ResponseWriter: w,
            buf:            &bytes.Buffer{},

        // Call next handler, passing the response wrapper:
        handler.ServeHTTP(mrw, r)

        // Now inspect response, and finally send it out:
        // (You can also modify it before sending it out!)
        if _, err := io.Copy(w, mrw.buf); err != nil {
            log.Printf("Failed to send out response: %v", err)

regex match any whitespace

Your regex should work 'as-is'. Assuming that it is doing what you want it to.

wordA(\s*)wordB(?! wordc)

This means match wordA followed by 0 or more spaces followed by wordB, but do not match if followed by wordc. Note the single space between ?! and wordc which means that wordA wordB wordc will not match, but wordA wordB wordc will.

Here are some example matches and the associated replacement output:

enter image description here

Note that all matches are replaced no matter how many spaces. There are a couple of other points: -

  • (?! wordc) is a negative lookahead, so you wont match lines wordA wordB wordc which is assume is intended (and is why the last line is not matched). Currently you are relying on the space after ?! to match the whitespace. You may want to be more precise and use (?!\swordc). If you want to match against more than one space before wordc you can use (?!\s*wordc) for 0 or more spaces or (?!\s*+wordc) for 1 or more spaces depending on what your intention is. Of course, if you do want to match lines with wordc after wordB then you shouldn't use a negative lookahead.

  • * will match 0 or more spaces so it will match wordAwordB. You may want to consider + if you want at least one space.

  • (\s*) - the brackets indicate a capturing group. Are you capturing the whitespace to a group for a reason? If not you could just remove the brackets, i.e. just use \s.

Update based on comment

Hello the problem is not the expression but the HTML out put   that are not considered as whitespace. it's a Joomla website.

Preserving your original regex you can use:


The only difference is that not the regex matches whitespace OR &nbsp;. I replaced wordc with \swordc since that is more explicit. Note as I have already pointed out that the negative lookahead ?! will not match when wordB is followed by a single whitespace and wordc. If you want to match multiple whitespaces then see my comments above. I also preserved the capture group around the whitespace, if you don't want this then remove the brackets as already described above.

Example matches:

enter image description here

Update select2 data without rebuilding the control

I solved this issue by using the ajax option and specifying a custom transport function.

see this fiddle Select2 dynamic options demo

Here is the relevant js to get this to work.

var $items = [];

let options = {
ajax: {
    transport: function(params, success, failure) {
    let items = $items;

    if ( && {
        items = items.filter(function(item) {
        return new RegExp(;

    let promise = new Promise(function(resolve, reject) {
        results: items

placeholder: 'Select item'


let count = $items.length + 1;

$('button').on('click', function() {
    id: count,
    text: 'Item' + count

How can I stop "property does not exist on type JQuery" syntax errors when using Typescript?

You can also use the ignore syntax instead of using (or better the 'as any') notation:

// @ts-ignore

SmartGit Installation and Usage on Ubuntu

Now on the Smartgit webpage (I don't know since when) there is the possibility to download directly the .deb package. Once installed, it will upgrade automagically itself when a new version is released.

Modal width (increase)

In Bootstrap 4 you have to use 'max-width' attribute and then it works perfectly.

<div id="modal_dialog" class="modal fade" tabindex="-1" role="dialog" style="display: none;">
<div class="modal-dialog" style="max-width: 1350px!important;" role="document">
    <div class="modal-content">
        <div class="modal-body">
            Sample text

What's the difference between StaticResource and DynamicResource in WPF?

A StaticResource will be resolved and assigned to the property during the loading of the XAML which occurs before the application is actually run. It will only be assigned once and any changes to resource dictionary ignored.

A DynamicResource assigns an Expression object to the property during loading but does not actually lookup the resource until runtime when the Expression object is asked for the value. This defers looking up the resource until it is needed at runtime. A good example would be a forward reference to a resource defined later on in the XAML. Another example is a resource that will not even exist until runtime. It will update the target if the source resource dictionary is changed.

What does <? php echo ("<pre>"); ..... echo("</pre>"); ?> mean?

$testArray = [
  "name"   => "Dinesh Madusanka",
  "gender" => "male"
  "name"   => "Tharaka Devinda",
  "gender" => "male"
  "name"   => "Dumidu Ranasinghearachchi",
  "gender" => "male"



  echo "<pre>";

Compiler error: "class, interface, or enum expected"

the main method should be declared in the your class like this :

public class derivativeQuiz_source{
    // bunch of methods .....

    public static void main(String args[])
        // code 

Remove last character from C++ string

str.erase( str.end()-1 )

Reference: std::string::erase() prototype 2

no c++11 or c++0x needed.

Remove all stylings (border, glow) from textarea

if no luck with above try to it a class or even id something like and then your style. or try to !important

Resize image with javascript canvas (smoothly)

I don't understand why nobody is suggesting createImageBitmap.

    { resizeWidth: 300, resizeHeight: 234, resizeQuality: 'high' }
.then(imageBitmap => 
    document.getElementById('canvas').getContext('2d').drawImage(imageBitmap, 0, 0)

works beautifully (assuming you set ids for image and canvas).

throw checked Exceptions from mocks with Mockito

Note that in general, Mockito does allow throwing checked exceptions so long as the exception is declared in the message signature. For instance, given

class BarException extends Exception {
  // this is a checked exception

interface Foo {
  Bar frob() throws BarException

it's legal to write:

Foo foo = mock(Foo.class);

However, if you throw a checked exception not declared in the method signature, e.g.

class QuxException extends Exception {
  // a different checked exception

Foo foo = mock(Foo.class);

Mockito will fail at runtime with the somewhat misleading, generic message:

Checked exception is invalid for this method!
Invalid: QuxException

This may lead you to believe that checked exceptions in general are unsupported, but in fact Mockito is only trying to tell you that this checked exception isn't valid for this method.

How do you return a JSON object from a Java Servlet

I do exactly what you suggest (return a String).

You might consider setting the MIME type to indicate you're returning JSON, though (according to this other stackoverflow post it's "application/json").

How can I create a text box for a note in markdown?

The simplest solution I've found to the exact same problem is to use a multiple line table with one row and no header (there is an image in the first column and the text in the second):

----------------------- ------------------------------------
![Tip](images/tip.png)\ Table multiline text bla bla bla bla
                        bla bla bla bla bla bla bla ... the
                        blank line below is important 


Another approach that might work (for PDF) is to use Latex default fbox directive :

 \fbox{My text!}

Or FancyBox module for more advanced features (and better looking boxes) :

Get remote registry value

If you need user's SID and browse remote HKEY_USERS folder, you can follow this script :

<# Replace following with yours and userAccountName with remote username #>
$userLogin = New-Object System.Security.Principal.NTAccount(““,”userAccountName“)
$userSID = $userLogin.Translate([System.Security.Principal.SecurityIdentifier])

<# We will open HKEY_USERS and with accurate user’s SID from remoteComputer #>
$remoteRegistry = [Microsoft.Win32.RegistryKey]::OpenRemoteBaseKey(‘Users’,”remoteComputer“)

<# We will then retrieve LocalName value from Control Panel / International subkeys #>

$key = $userSID.value+”\Control Panel\International”
$openKey = $remoteRegistry.OpenSubKey($key)

<# We can now retrieve any values #>

$localName = $openKey.GetValue(‘LocaleName’)

Source :

Difference between numeric, float and decimal in SQL Server

Guidelines from MSDN: Using decimal, float, and real Data

The default maximum precision of numeric and decimal data types is 38. In Transact-SQL, numeric is functionally equivalent to the decimal data type. Use the decimal data type to store numbers with decimals when the data values must be stored exactly as specified.

The behavior of float and real follows the IEEE 754 specification on approximate numeric data types. Because of the approximate nature of the float and real data types, do not use these data types when exact numeric behavior is required, such as in financial applications, in operations involving rounding, or in equality checks. Instead, use the integer, decimal, money, or smallmoney data types. Avoid using float or real columns in WHERE clause search conditions, especially the = and <> operators. It is best to limit float and real columns to > or < comparisons.

How do you run `apt-get` in a dockerfile behind a proxy?

Updated on 02/10/2018

With new feature in docker option --config, you needn't set Proxy in Dockerfile any more. You can have same Dockerfile to be used in and out corporate environment.

--config string      Location of client config files (default "~/.docker")

or environment variable DOCKER_CONFIG

`DOCKER_CONFIG` The location of your client configuration files.

$ export DOCKER_CONFIG=~/.docker

I recommend to set proxy with httpProxy, httpsProxy, ftpProxy and noProxy (The official document misses the variable ftpProxy which is useful sometimes)

     "httpProxy": "",
     "httpsProxy": "",
     "ftpProxy": "",
     "noProxy": "*,"

Adjust proxy IP and port if needed and save to ~/.docker/config.json

After yo set properly with it, you can run docker build and docker run as normal.

$ docker build -t demo . 

$ docker run -ti --rm demo env|grep -ri proxy
(standard input):http_proxy=
(standard input):HTTPS_PROXY=
(standard input):https_proxy=
(standard input):NO_PROXY=*,
(standard input):no_proxy=*,
(standard input):FTP_PROXY=
(standard input):ftp_proxy=
(standard input):HTTP_PROXY=

Old answer (Decommissioned)

Below setting in Dockerfile works for me. I tested in CoreOS, Vagrant and boot2docker. Suppose the proxy port is 3128

In Centos:

ENV http_proxy=ip:3128 
ENV https_proxy=ip:3128

In Ubuntu:

ENV http_proxy 'http://ip:3128'
ENV https_proxy 'http://ip:3128'

Be careful of the format, some have http in it, some haven't, some with single quota. if the IP address is, then the setting will be:

In Centos:

ENV http_proxy= 
ENV https_proxy=

In Ubuntu:

ENV http_proxy ''
ENV https_proxy ''

If you need set proxy in coreos, for example to pull the image

cat /etc/systemd/system/docker.service.d/http-proxy.conf


Eclipse: Java was started but returned error code=13

This is often caused by the (accidental) removal of the JRE folder that is set in the Eclipse configuration. You can try following these instructions from the Eclipse wiki on how to configure the eclipse.ini file to include the the JRE location, or alternatively, launch eclipse from the command prompt using VM arguments. I have tried them both myself and in my opinion, the command prompt option works much better.

Once you are able to launch Eclipse, make sure you verify the installed JRE location under Java --> Installed JREs in the Preferences window.

How to link 2 cell of excel sheet?

The simplest solution is to select the second cell, and press =. This will begin the fomula creation process. Now either type in the 1st cell reference (eg, A1) or click on the first cell and press enter. This should make the second cell reference the value of the first cell.

To read up more on different options for referencing see - This Article.

How to run a command in the background and get no output?

Run in a subshell to remove notifications and close STDOUT and STDERR:

(&>/dev/null &)

How to set the current working directory?

people using pandas package

import os
import pandas as pd

tar = os.chdir('<dir path only>') # do not mention file name here
print os.getcwd()# to print the path name in CLI

the following syntax to be used to import the file in python CLI

dataset(*just a variable) = pd.read_csv('new.csv')

Android: Difference between onInterceptTouchEvent and dispatchTouchEvent?

There is a lot of confusion about these methods, but it is actually not that complicated. Most of the confusion is because:

  1. If your View/ViewGroup or any of its children do not return true in onTouchEvent, dispatchTouchEvent and onInterceptTouchEvent will ONLY be called for MotionEvent.ACTION_DOWN. Without a true from onTouchEvent, the parent view will assume your view does not need the MotionEvents.
  2. When none of the children of a ViewGroup return true in onTouchEvent, onInterceptTouchEvent will ONLY be called for MotionEvent.ACTION_DOWN, even if your ViewGroup returns true in onTouchEvent.

Processing order is like this:

  1. dispatchTouchEvent is called.
  2. onInterceptTouchEvent is called for MotionEvent.ACTION_DOWN or when any of the children of the ViewGroup returned true in onTouchEvent.
  3. onTouchEvent is first called on the children of the ViewGroup and when none of the children returns true it is called on the View/ViewGroup.

If you want to preview TouchEvents/MotionEvents without disabling the events on your children, you must do two things:

  1. Override dispatchTouchEvent to preview the event and return super.dispatchTouchEvent(ev);
  2. Override onTouchEvent and return true, otherwise you won’t get any MotionEvent except MotionEvent.ACTION_DOWN.

If you want to detect some gesture like a swipe event, without disabling other events on your children as long as you did not detect the gesture, you can do it like this:

  1. Preview the MotionEvents as described above and set a flag when you detected your gesture.
  2. Return true in onInterceptTouchEvent when your flag is set to cancel MotionEvent processing by your children. This is also a convenient place to reset your flag, because onInterceptTouchEvent won’t be called again until the next MotionEvent.ACTION_DOWN.

Example of overrides in a FrameLayout (my example in is C# as I’m programming with Xamarin Android, but the logic is the same in Java):

public override bool DispatchTouchEvent(MotionEvent e)
    // Preview the touch event to detect a swipe:
    switch (e.ActionMasked)
        case MotionEventActions.Down:
            _processingSwipe = false;
            _touchStartPosition = e.RawX;
        case MotionEventActions.Move:
            if (!_processingSwipe)
                float move = e.RawX - _touchStartPosition;
                if (move >= _swipeSize)
                    _processingSwipe = true;
                    _cancelChildren = true;
    return base.DispatchTouchEvent(e);

public override bool OnTouchEvent(MotionEvent e)
    // To make sure to receive touch events, tell parent we are handling them:
    return true;

public override bool OnInterceptTouchEvent(MotionEvent e)
    // Cancel all children when processing a swipe:
    if (_cancelChildren)
        // Reset cancel flag here, as OnInterceptTouchEvent won't be called until the next MotionEventActions.Down:
        _cancelChildren = false;
        return true;
    return false;

Cocoa: What's the difference between the frame and the bounds?

try to run the code below

- (void)viewDidLoad {
    [super viewDidLoad];
    UIWindow *w = [[UIApplication sharedApplication] keyWindow];
    UIView *v = [w.subviews objectAtIndex:0];

    NSLog(@"%@", NSStringFromCGRect(v.frame));
    NSLog(@"%@", NSStringFromCGRect(v.bounds));

the output of this code is:

case device orientation is Portrait

{{0, 0}, {768, 1024}}
{{0, 0}, {768, 1024}}

case device orientation is Landscape

{{0, 0}, {768, 1024}}
{{0, 0}, {1024, 768}}

obviously, you can see the difference between frame and bounds

error running apache after xampp install server certificate does NOT include an ID which matches the server name

I was getting this error when trying to start Apache, there is no error with Apache. It's an dependency error on windows 8 - probably the same for 7. Just right click and run as Admin :)

If you're still getting an error check your Antivirus/Firewall is not blocking Xampp or port 443.

How to write a Python module/package?

Once you have defined your chosen commands, you can simply drag and drop the saved file into the Lib folder in your python program files.

>>> import mymodule 
>>> mymodule.myfunc()

Does Hive have a String split function?

There does exist a split function based on regular expressions. It's not listed in the tutorial, but it is listed on the language manual on the wiki:

split(string str, string pat)
   Split str around pat (pat is a regular expression) 

In your case, the delimiter "|" has a special meaning as a regular expression, so it should be referred to as "\\|".

How do I turn a python datetime into a string, with readable format date?

very old question, i know. but with the new f-strings (starting from python 3.6) there are fresh options. so here for completeness:

from datetime import datetime

dt =

# str.format
strg = '{:%B %d, %Y}'.format(dt)
print(strg)  # July 22, 2017

# datetime.strftime
strg = dt.strftime('%B %d, %Y')
print(strg)  # July 22, 2017

# f-strings in python >= 3.6
strg = f'{dt:%B %d, %Y}'
print(strg)  # July 22, 2017

strftime() and strptime() Behavior explains what the format specifiers mean.

Filename too long in Git for Windows

You should be able to run the command

git config --system core.longpaths true

or add it to one of your Git configuration files manually to turn this functionality on, once you are on a supported version of Git. It looks like maybe 1.9.0 and after.

How to stretch a fixed number of horizontal navigation items evenly and fully across a specified container

Instead of defining the width, you could just put a margin-left on your li, so that the spacing is consistent, and just make sure the margin(s)+li fit within 900px.

nav li {
  line-height: 87px;
  float: left;
  text-align: center;
  margin-left: 35px;

Hope this helps.

Pretty Printing a pandas dataframe

Maybe you're looking for something like this:

def tableize(df):
    if not isinstance(df, pd.DataFrame):
    df_columns = df.columns.tolist() 
    max_len_in_lst = lambda lst: len(sorted(lst, reverse=True, key=len)[0])
    align_center = lambda st, sz: "{0}{1}{0}".format(" "*(1+(sz-len(st))//2), st)[:sz] if len(st) < sz else st
    align_right = lambda st, sz: "{0}{1} ".format(" "*(sz-len(st)-1), st) if len(st) < sz else st
    max_col_len = max_len_in_lst(df_columns)
    max_val_len_for_col = dict([(col, max_len_in_lst(df.iloc[:,idx].astype('str'))) for idx, col in enumerate(df_columns)])
    col_sizes = dict([(col, 2 + max(max_val_len_for_col.get(col, 0), max_col_len)) for col in df_columns])
    build_hline = lambda row: '+'.join(['-' * col_sizes[col] for col in row]).join(['+', '+'])
    build_data = lambda row, align: "|".join([align(str(val), col_sizes[df_columns[idx]]) for idx, val in enumerate(row)]).join(['|', '|'])
    hline = build_hline(df_columns)
    out = [hline, build_data(df_columns, align_center), hline]
    for _, row in df.iterrows():
        out.append(build_data(row.tolist(), align_right))
    return "\n".join(out)

df = pd.DataFrame([[1, 2, 3], [11111, 22, 333]], columns=['a', 'b', 'c'])
print tableize(df)
|    a  |  b |   c |
|     1 |  2 |   3 |
| 11111 | 22 | 333 |

How to use vim in the terminal?

Get started quickly

You simply type vim into the terminal to open it and start a new file.

You can pass a filename as an option and it will open that file, e.g. vim main.c. You can open multiple files by passing multiple file arguments.

Vim has different modes, unlike most editors you have probably used. You begin in NORMAL mode, which is where you will spend most of your time once you become familiar with vim.

To return to NORMAL mode after changing to a different mode, press Esc. It's a good idea to map your Caps Lock key to Esc, as it's closer and nobody really uses the Caps Lock key.

The first mode to try is INSERT mode, which is entered with a for append after cursor, or i for insert before cursor.

To enter VISUAL mode, where you can select text, use v. There are many other variants of this mode, which you will discover as you learn more about vim.

To save your file, ensure you're in NORMAL mode and then enter the command :w. When you press :, you will see your command appear in the bottom status bar. To save and exit, use :x. To quit without saving, use :q. If you had made a change you wanted to discard, use :q!.

Configure vim to your liking

You can edit your ~/.vimrc file to configure vim to your liking. It's best to look at a few first (here's mine) and then decide which options suits your style.

This is how mine looks:

vim screenshot

To get the file explorer on the left, use NERDTree. For the status bar, use vim-airline. Finally, the color scheme is solarized.

Further learning

You can use man vim for some help inside the terminal. Alternatively, run vimtutor which is a good hands-on starting point.

It's a good idea to print out a Vim Cheatsheet and keep it in front of you while you're learning vim.

Good luck!

SQL Server 2008 - Help writing simple INSERT Trigger

cmsjr had the right solution. I just wanted to point out a couple of things for your future trigger development. If you are using the values statement in an insert in a trigger, there is a stong possibility that you are doing the wrong thing. Triggers fire once for each batch of records inserted, deleted, or updated. So if ten records were inserted in one batch, then the trigger fires once. If you are refering to the data in the inserted or deleted and using variables and the values clause then you are only going to get the data for one of those records. This causes data integrity problems. You can fix this by using a set-based insert as cmsjr shows above or by using a cursor. Don't ever choose the cursor path. A cursor in a trigger is a problem waiting to happen as they are slow and may well lock up your table for hours. I removed a cursor from a trigger once and improved an import process from 40 minutes to 45 seconds.

You may think nobody is ever going to add multiple records, but it happens more frequently than most non-database people realize. Don't write a trigger that will not work under all the possible insert, update, delete conditions. Nobody is going to use the one record at a time method when they have to import 1,000,000 sales target records from a new customer or update all the prices by 10% or delete all the records from a vendor whose products you don't sell anymore.

How to instantiate a javascript class in another js file?

// Create Customer class as follows:
export default class Customer {}

// Import the class 
// no need for .js extension in path cos gets inferred automatically
import Customer from './path/to/Customer'; 
// or
const Customer = require('./path/to/Customer') 

// Use the class
var customer = new Customer();
var name = customer.getName();

onclick event function in JavaScript

I suggest you do: <input type="button" value="button text" onclick="click()"> Hope this helps you!

Assigning more than one class for one event

Have you tried this:

 function doSomething() {
     if ($(this).hasClass('clickedTag')){
         // code here
     } else {
         // and here

 $('.tag1, .tag2').click(doSomething);

Adding a newline into a string in C#

You could also use string[] something = text.Split('@'). Make sure you use single quotes to surround the "@" to store it as a char type. This will store the characters up to and including each "@" as individual words in the array. You can then output each (element + System.Environment.NewLine) using a for loop or write it to a text file using System.IO.File.WriteAllLines([file path + name and extension], [array name]). If the specified file doesn't exist in that location it will be automatically created.

Installing a specific version of angular with angular cli

You can just have package.json with specific version and do npm install and it will install that version. Also you dont need to depend on angular-cli to develop your project.

Finish an activity from another activity

First call startactivity() then use finish()

How to programmatically set the ForeColor of a label to its default?

You can also use below format:

Label1.ForeColor = System.Drawing.ColorTranslator.FromHtml("#22FF99");


HyperLink1.ForeColor = System.Drawing.ColorTranslator.FromHtml("#22FF99");

How to check if an array value exists?

Well, first off an associative array can only have a key defined once, so this array would never exist. Otherwise, just use in_array() to determine if that specific array element is in an array of possible solutions.

How to print a dictionary's key?

import pprint

JUnit tests pass in Eclipse but fail in Maven Surefire

I suddenly experienced this error, and the solution for me was to disable to run tests in parallel.

Your milage may vary, since I could lower number of failing tests by configuring surefire to run parallel tests by ´classes´.:


As I wrote first, this was not enough for my test suite, so I completely disabled parallel by removing the <configuration> section.

Adding IN clause List to a JPA Query

public List<DealInfo> getDealInfos(List<String> dealIds) {
        String queryStr = "SELECT NEW com.admin.entity.DealInfo(deal.url, deal.url, deal.url, deal.url, deal.price, deal.value) " + "FROM Deal AS deal where in :inclList";
        TypedQuery<DealInfo> query = em.createQuery(queryStr, DealInfo.class);
        query.setParameter("inclList", dealIds);
        return query.getResultList();

Works for me with JPA 2, Jboss 7.0.2

pass **kwargs argument to another function with **kwargs

The ** syntax tells Python to collect keyword arguments into a dictionary. The save2 is passing it down as a non-keyword argument (a dictionary object). The openX is not seeing any keyword arguments so the **args doesn't get used. It's instead getting a third non-keyword argument (the dictionary). To fix that change the definition of the openX function.

def openX(filename, mode, kwargs):

How to check if the URL contains a given string?

Put in your js file

                var url = window.location.href;
                if (~url.indexOf("#product-consulation")) {
                    // $('html, body').animate({
                    //     scrollTop: $('#header').offset().top - 80
                    // }, 1000);
                } else {

How to pull remote branch from somebody else's repo

If antak's answer:

git fetch [email protected]:<THEIR USERNAME>/<REPO>.git <THEIR BRANCH>:<OUR NAME FOR BRANCH> 

gives you:

Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

Then (following Przemek D's advice) use


How to fix missing dependency warning when using useEffect React Hook?

You can remove the 2nd argument type array [] but the fetchBusinesses() will also be called every update. You can add an IF statement into the fetchBusinesses() implementation if you like.

React.useEffect(() => {

The other one is to implement the fetchBusinesses() function outside your component. Just don't forget to pass any dependency arguments to your fetchBusinesses(dependency) call, if any.

function fetchBusinesses (fetch) {
  return fetch("theURL", { method: "GET" })
    .then(res => normalizeResponseErrors(res))
    .then(res => res.json())
    .then(rcvdBusinesses => {
      // some stuff
    .catch(err => {
      // some error handling

function YourComponent (props) {
  const { fetch } = props;

  React.useEffect(() => {
  }, [fetch]);

  // ...

sql ORDER BY multiple values in specific order?

You can order by a selected column or other expressions.

Here an example, how to order by the result of a case-statement:

  SELECT col1
       , col2
    FROM tbl_Bill
   WHERE col1 = 0
ORDER BY -- order by case-statement
    CASE WHEN tbl_Bill.IsGen = 0 THEN 0
         WHEN tbl_Bill.IsGen = 1 THEN 1
         ELSE 2 END

The result will be a List starting with "IsGen = 0" rows, followed by "IsGen = 1" rows and all other rows a the end.

You could add more order-parameters at the end:

  SELECT col1
       , col2
    FROM tbl_Bill
   WHERE col1 = 0
ORDER BY -- order by case-statement
    CASE WHEN tbl_Bill.IsGen = 0 THEN 0
         WHEN tbl_Bill.IsGen = 1 THEN 1
         ELSE 2 END,

href image link download on click

No, it isn't. You will need something on the server to send a Content-Disposition header to set the file as an attachment instead of being inline. You could do this with plain Apache configuration though.

I've found an example of doing it using mod_rewrite, although I know there is a simpler way.

Python regex for integer?

You are apparently using Django.

You are probably better off just using models.IntegerField() instead of models.TextField(). Not only will it do the check for you, but it will give you the error message translated in several langs, and it will cast the value from it's type in the database to the type in your Python code transparently.

What is your favorite C programming trick?

I love empty if-else and while(0) operators.

For example:

#define CMD1(X) do { foo(x); bar(x); } while (0)
#define CMD2(X) if (1) { foo(x); bar(x); } else

How to use onSavedInstanceState example please

A good information: you don't need to check whether the Bundle object is null into the onCreate() method. Use the onRestoreInstanceState() method, which the system calls after the onStart() method. The system calls onRestoreInstanceState() only if there is a saved state to restore, so you do not need to check whether the Bundle is null

How to use the command update-alternatives --config java

If you want to switch the jdk on a regular basis (or update to a new one once it is released), it's very conveniant to use sdkman.

You can additional tools like maven with sdkman, too.

/usr/lib/x86_64-linux-gnu/ version CXXABI_1.3.8' not found

I had the same problem on my Ubuntu 14.04 when tried to install TopTracker. I got such errors:

/usr/share/toptracker/bin/TopTracker: /usr/lib/x86_64-linux-gnu/ version 'CXXABI_1.3.8' not found (required by /usr/share/toptracker/bin/TopTracker) /usr/share/toptracker/bin/TopTracker: /usr/lib/x86_64-linux-gnu/ version 'GLIBCXX_3.4.21' not found (required by /usr/share/toptracker/bin/TopTracker) /usr/share/toptracker/bin/TopTracker: /usr/lib/x86_64-linux-gnu/ version 'CXXABI_1.3.9' not found (required by /usr/share/toptracker/bin/TopTracker)

But I then installed gcc 4.9 version and problem gone:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-4.9 g++-4.9

How to remove the arrows from input[type="number"] in Opera

I've been using some simple CSS and it seems to remove them and work fine.

input[type=number]::-webkit-inner-spin-button, _x000D_
input[type=number]::-webkit-outer-spin-button { _x000D_
    -webkit-appearance: none;_x000D_
    -moz-appearance: none;_x000D_
    appearance: none;_x000D_
    margin: 0; _x000D_
<input type="number" step="0.01"/>

This tutorial from CSS Tricks explains in detail & also shows how to style them

What's the difference between window.location and document.location in JavaScript?

As far as I know, Both are same. For cross browser safety you can use window.location rather than document.location.

All modern browsers map document.location to window.location, but I still prefer window.location as that's what I've used since I wrote my first web page. it is more consistent.

you can also see document.location === window.location returns true, which clarifies that both are same.

ASP.NET 5 MVC: unable to connect to web server 'IIS Express'

In my case, I had to open up


folder and rename or delete existing config files. After this step, I ran the application and IISExpress generated new config files and the error was gone.

How to use python numpy.savetxt to write strings and float number to an ASCII file?

The currently accepted answer does not actually address the question, which asks how to save lists that contain both strings and float numbers. For completeness I provide a fully working example, which is based, with some modifications, on the link given in @joris comment.

import numpy as np

names  = np.array(['NAME_1', 'NAME_2', 'NAME_3'])
floats = np.array([ 0.1234 ,  0.5678 ,  0.9123 ])

ab = np.zeros(names.size, dtype=[('var1', 'U6'), ('var2', float)])
ab['var1'] = names
ab['var2'] = floats

np.savetxt('test.txt', ab, fmt="%10s %10.3f")

Update: This example also works properly in Python 3 by using the 'U6' Unicode string dtype, when creating the ab structured array, instead of the 'S6' byte string. The latter dtype would work in Python 2.7, but would write strings like b'NAME_1' in Python 3.

Shell Script: Execute a python program from within a shell script

Method 1 - Create a shell script:

Suppose you have a python file Create a file called that contains


mark it executable using

$ chmod +x

then run it

$ ./

Method 2 (BETTER) - Make the python itself run from shell:

Modify your script and add this as the first line

#!/usr/bin/env python

mark it executable using

$ chmod +x

then run it

$ ./

What is the best way to compare 2 folder trees on windows?

SyncToy is a free application from Microsoft with a "Preview" mode for comparing two paths. For example:

SyncToy Preview screenshot (source:

You can then choose one of three modes ("Synchronize", "Echo" and "Contribute") to resolve the differences.

Lastly, it comes with SyncToyCmd for creating and synchronizing folder pairs from the CLI or a Scheduled Task.

Trying to pull files from my Github repository: "refusing to merge unrelated histories"

Execute the following command:

git pull origin master --allow-unrelated-histories

A merge vim will open. Add some merging message and:

  1. Press ESC
  2. Press Shift + ';'
  3. Press 'w' and then press 'q'.

And you are good to go.

Reading Space separated input in python

Assuming you are on Python 3, you can use this syntax

inputs = list(map(str,input().split()))

if you want to access individual element you can do it like that

m, n = map(str,input().split())

How to run Selenium WebDriver test cases in Chrome

You need to install the Chrome driver. You can install this package using NuGet as shown below:

How to get start and end of day in Javascript?

If you're just interested in timestamps in GMT you can also do this, which can be conveniently adapted for different intervals (hour: 1000 * 60 * 60, 12 hours: 1000 * 60 * 60 * 12, etc.)

const interval = 1000 * 60 * 60 * 24; // 24 hours in milliseconds

let startOfDay = Math.floor( / interval) * interval;
let endOfDay = startOfDay + interval - 1; // 23:59:59:9999

<DIV> inside link (<a href="">) tag

No, the link assigned to the containing <a> will be assigned to every elements inside it.

And, this is not the proper way. You can make a <a> behave like a <div>.

An Example [Demo]


a.divlink { 


    <a class="divlink" href="yourlink.html">
         The text or elements inside the elements
    <a class="divlink" href="yourlink2.html">
         Another text or element

How to send JSON instead of a query string with $.ajax?

No, the dataType option is for parsing the received data.

To post JSON, you will need to stringify it yourself via JSON.stringify and set the processData option to false.

    url: url,
    type: "POST",
    data: JSON.stringify(data),
    processData: false,
    contentType: "application/json; charset=UTF-8",
    complete: callback

Note that not all browsers support the JSON object, and although jQuery has .parseJSON, it has no stringifier included; you'll need another polyfill library.

Adding :default => true to boolean in existing Rails column

If you don't want to create another migration-file for a small, recent change - from Rails Console:

ActiveRecord::Migration.change_column :profiles, :show_attribute, :boolean, :default => true

Then exit and re-enter rails console, so DB-Changes will be in-effect. Then, if you do this ...

You should see the "show_attribute" default-value as true.

For existing records, if you want to preserve existing "false" settings and only update "nil" values to your new default:

Profile.all.each{|profile| profile.update_attributes(:show_attribute => (profile.show_attribute == nil ? true : false))  }

Update the migration that created this table, so any future builds of the DB will get it right from the onset. Also run the same process on any deployed-instances of the DB.

If using the "new db migration" method, you can do the update of existing nil-values in that migration.

How to convert a GUID to a string in C#?

Guid guidId = Guid.Parse("xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx");
string guidValue = guidId.ToString("D"); //return with hyphens

TypeError: only integer scalar arrays can be converted to a scalar index with 1D numpy indices array

Perhaps the error message is somewhat misleading, but the gist is that X_train is a list, not a numpy array. You cannot use array indexing on it. Make it an array first:

out_images = np.array(X_train)[indices.astype(int)]

Eclipse interface icons very small on high resolution screen in Windows 8.1

Jae's above solution worked for me. The manifest solution didn't work for me. Thanks Jae.

Setup:On my windows 8.1 64 bit non tablet laptop I downloaded eclipse 64 bit with jdk 64 bit.

  1. Right mouse click on desktop to access screen resolution and lowered the screen resolution display from 3000 level to 2048 x 1152.
  2. Click on make text and other items larger or smaller link and changed it to large 150% instead of extra extra large - 250%.
  3. Logged out and Logged back in.
  4. Restart Eclipse and the icons are now visible even if it is a bit smaller, but much more legible now.

Spring 3.0 - Unable to locate Spring NamespaceHandler for XML schema namespace []

Add the following dependency in your pom.xml file and if you are using IntelliJ then add the same jars to WEB-INF->lib folder.... path is Project Structure -> Atrifacts -> Select jar from Available Elements pane and double click. It will add to respective folder


File Upload without Form

Try this puglin simpleUpload, no need form


<input type="file" name="arquivo" id="simpleUpload" multiple >
<button type="button" id="enviar">Enviar</button>


  url: 'upload.php',
  trigger: '#enviar',
  success: function(data){
    alert('Envio com sucesso');


Turning error reporting off php

Does this work?

display_errors = Off

Also, what version of php are you using?

How can I multiply all items in a list together with Python?

Numpy has the prod() function that returns the product of a list, or in this case since it's numpy, it's the product of an array over a given axis:

import numpy
a = [1,2,3,4,5,6]
b =

...or else you can just import

from numpy import prod
a = [1,2,3,4,5,6]
b = prod(a)

List of zeros in python


you can replace 4 in the above example with whatever number you want.

Is there an exponent operator in C#?

I'm surprised no one has mentioned this, but for the simple (and probably most encountered) case of squaring, you just multiply by itself.

float someNumber;

float result = someNumber * someNumber;

How to call external url in jquery?

Follow the below simple steps you will able to get the result

Step 1- Create one internal function getDetailFromExternal in your back end. step 2- In that function call the external url by using cUrl like below function

 function getDetailFromExternal($p1,$p2) {

        $url = "http://request url with parameters";
        $ch = curl_init();
        curl_setopt_array($ch, array(
            CURLOPT_URL => $url,
            CURLOPT_RETURNTRANSFER => true            

        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
        $output = curl_exec($ch);
        echo $output;

Step 3- Call that internal function from your front end by using javascript/jquery Ajax.

Select unique values with 'select' function in 'dplyr' library

The dplyr select function selects specific columns from a data frame. To return unique values in a particular column of data, you can use the group_by function. For example:


# Fake data
dat = data.frame(x=sample(1:10,100, replace=TRUE))

# Return the distinct values of x
dat %>%
  group_by(x) %>%

1   1
2   2
3   3
4   4
5   5
6   6
7   7
8   8
9   9
10 10

If you want to change the column name you can add the following:

dat %>%
  group_by(x) %>%
  summarise() %>%

This both selects column x from among all the columns in the data frame that dplyr returns (and of course there's only one column in this case) and changes its name to unique.x.

You can also get the unique values directly in base R with unique(dat$x).

If you have multiple variables and want all unique combinations that appear in the data, you can generalize the above code as follows:

dat = data.frame(x=sample(1:10,100, replace=TRUE), 
                 y=sample(letters[1:5], 100, replace=TRUE))

dat %>% 
  group_by(x,y) %>%
  summarise() %>%
  select(unique.x=x, unique.y=y)

How can I use Html.Action?

first, create a class to hold your parameters:

public class PkRk {
    public int pk { get; set; }
    public int rk { get; set; }

then, use the Html.Action passing the parameters:

Html.Action("PkRkAction", new { pkrk = new PkRk { pk=400, rk=500} })

and use in Controller:

public ActionResult PkRkAction(PkRk pkrk) {
    return PartialView(pkrk);

How to access the correct `this` inside a callback?

this in JS:

The value of this in JS is 100% determined by how a function is called, and not how it is defined. We can relatively easily find the value of this by the 'left of the dot rule':

  1. When the function is created using the function keyword the value of this is the object left of the dot of the function which is called
  2. If there is no object left of the dot then the value of this inside a function is often the global object (global in node, window in browser). I wouldn't recommend using the this keyword here because it is less explicit than using something like window!
  3. There exist certain constructs like arrow functions and functions created using the Function.prototype.bind() a function that can fix the value of this. These are exceptions of the rule but are really helpful to fix the value of this.

Example in nodeJS = 'module data';
// This outside a function in node refers to module.exports object

const obj1 = {
    data: "obj1 data",
    met1: function () {
    met2: () => {

const obj2 = {
    data: "obj2 data",
    test1: function () {
    test2: function () {
    test3: obj1.met1,
    test4: obj1.met2,



enter image description here

Let me walk you through the outputs 1 by 1 (ignoring the first log starting from the second):

  1. this is obj2 because of the left of the dot rule, we can see how test1 is called obj2.test1();. obj2 is left of the dot and thus the this value.
  2. Even though obj2 is left of the dot, test2 is bound to obj1 via the bind() method. So the this value is obj1.
  3. obj2 is left of the dot from the function which is called: obj2.test3(). Therefore obj2 will be the value of this.
  4. In this case: obj2.test4() obj2 is left of the dot. However, arrow functions don't have their own this binding. Therefore it will bind to the this value of the outer scope which is the module.exports an object which was logged in the beginning.
  5. We can also specify the value of this by using the call function. Here we can pass in the desired this value as an argument, which is obj2 in this case.

How can I find out if an .EXE has Command-Line Options?

Invoke it from the shell, with an argument like /? or --help. Those are the usual help switches.

Groovy Shell warning "Could not open/create prefs root node ..."

If anyone is trying to solve this on a 64-bit version of Windows, you might need to create the following key:


How to encrypt/decrypt data in php?


Starting with your table definition:

- UserID
- Fname
- Lname
- Email
- Password
- IV

Here are the changes:

  1. The fields Fname, Lname and Email will be encrypted using a symmetric cipher, provided by OpenSSL,
  2. The IV field will store the initialisation vector used for encryption. The storage requirements depend on the cipher and mode used; more about this later.
  3. The Password field will be hashed using a one-way password hash,


Cipher and mode

Choosing the best encryption cipher and mode is beyond the scope of this answer, but the final choice affects the size of both the encryption key and initialisation vector; for this post we will be using AES-256-CBC which has a fixed block size of 16 bytes and a key size of either 16, 24 or 32 bytes.

Encryption key

A good encryption key is a binary blob that's generated from a reliable random number generator. The following example would be recommended (>= 5.3):

$key_size = 32; // 256 bits
$encryption_key = openssl_random_pseudo_bytes($key_size, $strong);
// $strong will be true if the key is crypto safe

This can be done once or multiple times (if you wish to create a chain of encryption keys). Keep these as private as possible.


The initialisation vector adds randomness to the encryption and required for CBC mode. These values should be ideally be used only once (technically once per encryption key), so an update to any part of a row should regenerate it.

A function is provided to help you generate the IV:

$iv_size = 16; // 128 bits
$iv = openssl_random_pseudo_bytes($iv_size, $strong);


Let's encrypt the name field, using the earlier $encryption_key and $iv; to do this, we have to pad our data to the block size:

function pkcs7_pad($data, $size)
    $length = $size - strlen($data) % $size;
    return $data . str_repeat(chr($length), $length);

$name = 'Jack';
$enc_name = openssl_encrypt(
    pkcs7_pad($name, 16), // padded data
    'AES-256-CBC',        // cipher and mode
    $encryption_key,      // secret key
    0,                    // options (not used)
    $iv                   // initialisation vector

Storage requirements

The encrypted output, like the IV, is binary; storing these values in a database can be accomplished by using designated column types such as BINARY or VARBINARY.

The output value, like the IV, is binary; to store those values in MySQL, consider using BINARY or VARBINARY columns. If this is not an option, you can also convert the binary data into a textual representation using base64_encode() or bin2hex(), doing so requires between 33% to 100% more storage space.


Decryption of the stored values is similar:

function pkcs7_unpad($data)
    return substr($data, 0, -ord($data[strlen($data) - 1]));

$row = $result->fetch(PDO::FETCH_ASSOC); // read from database result
// $enc_name = base64_decode($row['Name']);
// $enc_name = hex2bin($row['Name']);
$enc_name = $row['Name'];
// $iv = base64_decode($row['IV']);
// $iv = hex2bin($row['IV']);
$iv = $row['IV'];

$name = pkcs7_unpad(openssl_decrypt(

Authenticated encryption

You can further improve the integrity of the generated cipher text by appending a signature that's generated from a secret key (different from the encryption key) and the cipher text. Before the cipher text is decrypted, the signature is first verified (preferably with a constant-time comparison method).


// generate once, keep safe
$auth_key = openssl_random_pseudo_bytes(32, $strong);

// authentication
$auth = hash_hmac('sha256', $enc_name, $auth_key, true);
$auth_enc_name = $auth . $enc_name;

// verification
$auth = substr($auth_enc_name, 0, 32);
$enc_name = substr($auth_enc_name, 32);
$actual_auth = hash_hmac('sha256', $enc_name, $auth_key, true);

if (hash_equals($auth, $actual_auth)) {
    // perform decryption

See also: hash_equals()


Storing a reversible password in your database must be avoided as much as possible; you only wish to verify the password rather than knowing its contents. If a user loses their password, it's better to allow them to reset it rather than sending them their original one (make sure that password reset can only be done for a limited time).

Applying a hash function is a one-way operation; afterwards it can be safely used for verification without revealing the original data; for passwords, a brute force method is a feasible approach to uncover it due to its relatively short length and poor password choices of many people.

Hashing algorithms such as MD5 or SHA1 were made to verify file contents against a known hash value. They're greatly optimized to make this verification as fast as possible while still being accurate. Given their relatively limited output space it was easy to build a database with known passwords and their respective hash outputs, the rainbow tables.

Adding a salt to the password before hashing it would render a rainbow table useless, but recent hardware advancements made brute force lookups a viable approach. That's why you need a hashing algorithm that's deliberately slow and simply impossible to optimize. It should also be able to increase the load for faster hardware without affecting the ability to verify existing password hashes to make it future proof.

Currently there are two popular choices available:

  1. PBKDF2 (Password Based Key Derivation Function v2)
  2. bcrypt (aka Blowfish)

This answer will use an example with bcrypt.


A password hash can be generated like this:

$password = 'my password';
$random = openssl_random_pseudo_bytes(18);
$salt = sprintf('$2y$%02d$%s',
    13, // 2^n cost factor
    substr(strtr(base64_encode($random), '+', '.'), 0, 22)

$hash = crypt($password, $salt);

The salt is generated with openssl_random_pseudo_bytes() to form a random blob of data which is then run through base64_encode() and strtr() to match the required alphabet of [A-Za-z0-9/.].

The crypt() function performs the hashing based on the algorithm ($2y$ for Blowfish), the cost factor (a factor of 13 takes roughly 0.40s on a 3GHz machine) and the salt of 22 characters.


Once you have fetched the row containing the user information, you validate the password in this manner:

$given_password = $_POST['password']; // the submitted password
$db_hash = $row['Password']; // field with the password hash

$given_hash = crypt($given_password, $db_hash);

if (isEqual($given_hash, $db_hash)) {
    // user password verified

// constant time string compare
function isEqual($str1, $str2)
    $n1 = strlen($str1);
    if (strlen($str2) != $n1) {
        return false;
    for ($i = 0, $diff = 0; $i != $n1; ++$i) {
        $diff |= ord($str1[$i]) ^ ord($str2[$i]);
    return !$diff;

To verify a password, you call crypt() again but you pass the previously calculated hash as the salt value. The return value yields the same hash if the given password matches the hash. To verify the hash, it's often recommended to use a constant-time comparison function to avoid timing attacks.

Password hashing with PHP 5.5

PHP 5.5 introduced the password hashing functions that you can use to simplify the above method of hashing:

$hash = password_hash($password, PASSWORD_BCRYPT, ['cost' => 13]);

And verifying:

if (password_verify($given_password, $db_hash)) {
    // password valid

See also: password_hash(), password_verify()

How do I define a method in Razor?

You could also do it with a Func like this

    var getStyle = new Func<int, int, string>((width, margin) => string.Format("width: {0}px; margin: {1}px;", width, margin));

<div style="@getStyle(50, 2)"></div>

Base64 Decoding in iOS 7+

Swift 3+

let plainString = "foo"


let plainData = .utf8)
let base64String = plainData?.base64EncodedString()
print(base64String!) // Zm9v


if let decodedData = Data(base64Encoded: base64String!),
   let decodedString = String(data: decodedData, encoding: .utf8) {
  print(decodedString) // foo

Swift < 3

let plainString = "foo"


let plainData = plainString.dataUsingEncoding(NSUTF8StringEncoding)
let base64String = plainData?.base64EncodedStringWithOptions(NSDataBase64EncodingOptions(rawValue: 0))
print(base64String!) // Zm9v


let decodedData = NSData(base64EncodedString: base64String!, options: NSDataBase64DecodingOptions(rawValue: 0))
let decodedString = NSString(data: decodedData, encoding: NSUTF8StringEncoding)
print(decodedString) // foo


NSString *plainString = @"foo";


NSData *plainData = [plainString dataUsingEncoding:NSUTF8StringEncoding];
NSString *base64String = [plainData base64EncodedStringWithOptions:0];
NSLog(@"%@", base64String); // Zm9v


NSData *decodedData = [[NSData alloc] initWithBase64EncodedString:base64String options:0];
NSString *decodedString = [[NSString alloc] initWithData:decodedData encoding:NSUTF8StringEncoding];
NSLog(@"%@", decodedString); // foo 

How to document a method with parameter(s)?

If you plan to use Sphinx to document your code, it is capable of producing nicely formatted HTML docs for your parameters with their 'signatures' feature.

How can I read and parse CSV files in C++?

This is an old thread but its still at the top of search results, so I'm adding my solution using std::stringstream and a simple string replace method by Yves Baumes I found here.

The following example will read a file line by line, ignore comment lines starting with // and parse the other lines into a combination of strings, ints and doubles. Stringstream does the parsing, but expects fields to be delimited by whitespace, so I use stringreplace to turn commas into spaces first. It handles tabs ok, but doesn't deal with quoted strings.

Bad or missing input is simply ignored, which may or may not be good, depending on your circumstance.

#include <string>
#include <sstream>
#include <fstream>

void StringReplace(std::string& str, const std::string& oldStr, const std::string& newStr)
// code by  Yves Baumes
  size_t pos = 0;
  while((pos = str.find(oldStr, pos)) != std::string::npos)
     str.replace(pos, oldStr.length(), newStr);
     pos += newStr.length();

void LoadCSV(std::string &filename) {
   std::ifstream stream(filename);
   std::string in_line;
   std::string Field;
   std::string Chan;
   int ChanType;
   double Scale;
   int Import;
   while (std::getline(stream, in_line)) {
      StringReplace(in_line, ",", " ");
      std::stringstream line(in_line);
      line >> Field >> Chan >> ChanType >> Scale >> Import;
      if (Field.substr(0,2)!="//") {
         // do your stuff 
         // this is CBuilder code for demonstration, sorry
         ShowMessage((String)Field.c_str() + "\n" + Chan.c_str() + "\n" + IntToStr(ChanType) + "\n" +FloatToStr(Scale) + "\n" +IntToStr(Import));

Java - Convert String to valid URI object

I ended up using the httpclient-4.3.6:

import org.apache.http.client.utils.URIBuilder;
public static void main (String [] args) {
    URIBuilder uri = new URIBuilder();
    .setParameter("username", "Hello Günter")
    .setParameter("p1", "parameter 1");

Output will be:

How to make a div with no content have a width?

Either use padding , height or &nbsp for width to take effect with empty div


Non zero min-height also works great

How to enable DataGridView sorting when user clicks on the column header?

put this line in your windows form (on load or better in a public method like "binddata" ):

// bind the data and make the grid sortable 
this.datagridview1.MakeSortable( myenumerablecollection ); 

Put this code in a file called DataGridViewExtensions.cs (or similar)

// MakeSortable extension. 
// this will make any enumerable collection sortable on a datagrid view.  

// Enables sort on all cols of a DatagridView 


    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Threading.Tasks;
    using System.Windows.Forms;

    public static class DataGridViewExtensions
    public static void MakeSortable<T>(
        this DataGridView dataGridView, 
        IEnumerable<T> dataSource,
        SortOrder defaultSort = SortOrder.Ascending, 
        SortOrder initialSort = SortOrder.None)
        var sortProviderDictionary = new Dictionary<int, Func<SortOrder, IEnumerable<T>>>();
        var previousSortOrderDictionary = new Dictionary<int, SortOrder>();
        var itemType = typeof(T);
        dataGridView.DataSource = dataSource;
        foreach (DataGridViewColumn c in dataGridView.Columns)
            object Provider(T info) => itemType.GetProperty(c.Name)?.GetValue(info);
            sortProviderDictionary[c.Index] = so => so != defaultSort ? 
                dataSource.OrderByDescending<T, object>(Provider) : 
            previousSortOrderDictionary[c.Index] = initialSort;

        async Task DoSort(int index)

            switch (previousSortOrderDictionary[index])
                case SortOrder.Ascending:
                    previousSortOrderDictionary[index] = SortOrder.Descending;
                case SortOrder.None:
                case SortOrder.Descending:
                    previousSortOrderDictionary[index] = SortOrder.Ascending;
                    throw new ArgumentOutOfRangeException();

            IEnumerable<T> sorted = null;
            dataGridView.Cursor = Cursors.WaitCursor;
            dataGridView.Enabled = false;
            await Task.Run(() => sorted = sortProviderDictionary[index](previousSortOrderDictionary[index]).ToList());
            dataGridView.DataSource = sorted;
            dataGridView.Enabled = true;
            dataGridView.Cursor = Cursors.Default;


        dataGridView.ColumnHeaderMouseClick+= (object sender, DataGridViewCellMouseEventArgs e) => DoSort(index: e.ColumnIndex);

How do I create a user with the same privileges as root in MySQL/MariaDB?

% mysql --user=root mysql
CREATE USER 'monty'@'localhost' IDENTIFIED BY 'some_pass';
CREATE USER 'monty'@'%' IDENTIFIED BY 'some_pass';
CREATE USER 'admin'@'localhost';
GRANT RELOAD,PROCESS ON *.* TO 'admin'@'localhost';
CREATE USER 'dummy'@'localhost';

Java generating Strings with placeholders

This can be done in a single line without the use of library. Please check java.text.MessageFormat class.


String stringWithPlaceHolder = "test String with placeholders {0} {1} {2} {3}";
String formattedStrin = java.text.MessageFormat.format(stringWithPlaceHolder, "place-holder-1", "place-holder-2", "place-holder-3", "place-holder-4");

Output will be

test String with placeholders place-holder-1 place-holder-2 place-holder-3 place-holder-4

Where is the itoa function in Linux?

I have used _itoa(...) on RedHat 6 and GCC compiler. It works.

Default values and initialization in Java

I wrote following function to return a default representation 0 or false of a primitive or Number:

 * Retrieves the default value 0 / false for any primitive representative or
 * {@link Number} type.
 * @param type
 * @return
public static <T> T getDefault(final Class<T> type)
    if (type.equals(Long.class) || type.equals(Long.TYPE))
        return (T) new Long(0);
    else if (type.equals(Integer.class) || type.equals(Integer.TYPE))
        return (T) new Integer(0);
    else if (type.equals(Double.class) || type.equals(Double.TYPE))
        return (T) new Double(0);
    else if (type.equals(Float.class) || type.equals(Float.TYPE))
        return (T) new Float(0);
    else if (type.equals(Short.class) || type.equals(Short.TYPE))
        return (T) new Short((short) 0);
    else if (type.equals(Byte.class) || type.equals(Byte.TYPE))
        return (T) new Byte((byte) 0);
    else if (type.equals(Character.class) || type.equals(Character.TYPE))
        return (T) new Character((char) 0);
    else if (type.equals(Boolean.class) || type.equals(Boolean.TYPE))
        return (T) new Boolean(false);
    else if (type.equals(BigDecimal.class))
        return (T) BigDecimal.ZERO;
    else if (type.equals(BigInteger.class))
        return (T) BigInteger.ZERO;
    else if (type.equals(AtomicInteger.class))
        return (T) new AtomicInteger();
    else if (type.equals(AtomicLong.class))
        return (T) new AtomicLong();
    else if (type.equals(DoubleAdder.class))
        return (T) new DoubleAdder();
        return null;

I use it in hibernate ORM projection queries when the underlying SQL query returns null instead of 0.

 * Retrieves the unique result or zero, <code>false</code> if it is
 * <code>null</code> and represents a number
 * @param criteria
 * @return zero if result is <code>null</code>
public static <T> T getUniqueResultDefault(final Class<T> type, final Criteria criteria)
    final T result = (T) criteria.uniqueResult();

    if (result != null)
        return result;
        return Utils.getDefault(type);

One of the many unnecessary complex things about Java making it unintuitive to use. Why instance variables are initialized with default 0 but local are not is not logical. Similar why enums dont have built in flag support and many more options. Java lambda is a nightmare compared to C# and not allowing class extension methods is also a big problem.

Java ecosystem comes up with excuses why its not possible but me as the user / developer i dont care about their excuses. I want easy approach and if they dont fix those things they will loose big in the future since C# and other languages are not waiting to make life of developers more simple. Its just sad to see the decline in the last 10 years since i work daily with Java.

LISTAGG function: "result of string concatenation is too long"

You are exceeding the SQL limit of 4000 bytes which applies to LISTAGG as well.

SQL> SELECT listagg(text, ',') WITHIN GROUP (
  3  FROM
  4    (SELECT to_char(to_date(level,'j'), 'jsp') text FROM dual CONNECT BY LEVEL < 250
  5    )
  6  /
SELECT listagg(text, ',') WITHIN GROUP (
ERROR at line 1:
ORA-01489: result of string concatenation is too long

As a workaround, you could use XMLAGG.

For example,

SQL> SET LONG 2000000
SQL> SET pagesize 50000
SQL> SELECT rtrim(xmlagg(XMLELEMENT(e,text,',').EXTRACT('//text()')
  2                     ).GetClobVal(),',') very_long_text
  3  FROM
  4    (SELECT to_char(to_date(level,'j'), 'jsp') text FROM dual CONNECT BY LEVEL < 250
  5    )
  6  /

our,ninety-five,ninety-six,ninety-seven,ninety-eight,ninety-nine,one hundred,one
 hundred one,one hundred two,one hundred three,one hundred four,one hundred five
,one hundred six,one hundred seven,one hundred eight,one hundred nine,one hundre
d ten,one hundred eleven,one hundred twelve,one hundred thirteen,one hundred fou
rteen,one hundred fifteen,one hundred sixteen,one hundred seventeen,one hundred
eighteen,one hundred nineteen,one hundred twenty,one hundred twenty-one,one hund
red twenty-two,one hundred twenty-three,one hundred twenty-four,one hundred twen
ty-five,one hundred twenty-six,one hundred twenty-seven,one hundred twenty-eight
,one hundred twenty-nine,one hundred thirty,one hundred thirty-one,one hundred t
hirty-two,one hundred thirty-three,one hundred thirty-four,one hundred thirty-fi
ve,one hundred thirty-six,one hundred thirty-seven,one hundred thirty-eight,one
hundred thirty-nine,one hundred forty,one hundred forty-one,one hundred forty-tw
o,one hundred forty-three,one hundred forty-four,one hundred forty-five,one hund
red forty-six,one hundred forty-seven,one hundred forty-eight,one hundred forty-
nine,one hundred fifty,one hundred fifty-one,one hundred fifty-two,one hundred f
ifty-three,one hundred fifty-four,one hundred fifty-five,one hundred fifty-six,o
ne hundred fifty-seven,one hundred fifty-eight,one hundred fifty-nine,one hundre
d sixty,one hundred sixty-one,one hundred sixty-two,one hundred sixty-three,one
hundred sixty-four,one hundred sixty-five,one hundred sixty-six,one hundred sixt
y-seven,one hundred sixty-eight,one hundred sixty-nine,one hundred seventy,one h
undred seventy-one,one hundred seventy-two,one hundred seventy-three,one hundred
 seventy-four,one hundred seventy-five,one hundred seventy-six,one hundred seven
ty-seven,one hundred seventy-eight,one hundred seventy-nine,one hundred eighty,o
ne hundred eighty-one,one hundred eighty-two,one hundred eighty-three,one hundre
d eighty-four,one hundred eighty-five,one hundred eighty-six,one hundred eighty-
seven,one hundred eighty-eight,one hundred eighty-nine,one hundred ninety,one hu
ndred ninety-one,one hundred ninety-two,one hundred ninety-three,one hundred nin
ety-four,one hundred ninety-five,one hundred ninety-six,one hundred ninety-seven
,one hundred ninety-eight,one hundred ninety-nine,two hundred,two hundred one,tw
o hundred two,two hundred three,two hundred four,two hundred five,two hundred si
x,two hundred seven,two hundred eight,two hundred nine,two hundred ten,two hundr
ed eleven,two hundred twelve,two hundred thirteen,two hundred fourteen,two hundr
ed fifteen,two hundred sixteen,two hundred seventeen,two hundred eighteen,two hu
ndred nineteen,two hundred twenty,two hundred twenty-one,two hundred twenty-two,
two hundred twenty-three,two hundred twenty-four,two hundred twenty-five,two hun
dred twenty-six,two hundred twenty-seven,two hundred twenty-eight,two hundred tw
enty-nine,two hundred thirty,two hundred thirty-one,two hundred thirty-two,two h
undred thirty-three,two hundred thirty-four,two hundred thirty-five,two hundred
thirty-six,two hundred thirty-seven,two hundred thirty-eight,two hundred thirty-
nine,two hundred forty,two hundred forty-one,two hundred forty-two,two hundred f
orty-three,two hundred forty-four,two hundred forty-five,two hundred forty-six,t
wo hundred forty-seven,two hundred forty-eight,two hundred forty-nine

If you want to concatenate multiple columns which itself have 4000 bytes, then you can concatenate the XMLAGG output of each column to avoid the SQL limit of 4000 bytes.

For example,

  ( SELECT 1 id, rpad('a1',4000,'*') col1, rpad('b1',4000,'*') col2 FROM dual
  SELECT 2 id, rpad('a2',4000,'*') col1, rpad('b2',4000,'*') col2 FROM dual
       rtrim(xmlagg(XMLELEMENT(e,col1,',').EXTRACT('//text()') ).GetClobVal(), ',')
       rtrim(xmlagg(XMLELEMENT(e,col2,',').EXTRACT('//text()') ).GetClobVal(), ',') 
       AS very_long_text

Rails 4: List of available datatypes

It is important to know not only the types but the mapping of these types to the database types, too:

enter image description here

enter image description here

Source added - Agile Web Development with Rails 4

ORA-12154: TNS:could not resolve the connect identifier specified (PLSQL Developer)

Just wanted to add -- apparently this can also be caused by installing Instant Client for 10, then realizing you want the full install and installing it again in a parallel directory. I don't know why this broke it.

How to get request URL in Spring Boot RestController

Add a parameter of type UriComponentsBuilder to your controller method. Spring will give you an instance that's preconfigured with the URI for the current request, and you can then customize it (such as by using MvcUriComponentsBuilder.relativeTo to point at a different controller using the same prefix).

How to find the length of an array in shell?

$ a=(1 2 3 4)
$ echo ${#a[@]}

How to enable production mode?

Most of the time prod mode is not needed during development time. So our workaround is to only enable it when it is NOT localhost.

In your browsers' main.ts where you define your root AppModule:

const isLocal: boolean = /localhost/.test(;
!isLocal && enableProdMode();

The isLocal can also be used for other purposes like enableTracing for the RouterModule for better debugging stack trace during dev phase.

How to select top n rows from a datatable/dataview in ASP.NET

You could modify the query. If you are using SQL Server at the back, you can use Select top n query for such need. The current implements fetch the whole data from database. Selecting only the required number of rows will give you a performance boost as well.

How to control size of list-style-type disc in CSS?

If you choose to use inline SVG to render your bullets, you can use width and height properties to control their size:

ul {_x000D_
  list-style-image: url("data:image/svg+xml;utf8,<svg xmlns='' width='10' height='10' viewBox='-1 -1 2 2'><circle r='1' /></svg>");_x000D_
.x {_x000D_
  list-style-image: url("data:image/svg+xml;utf8,<svg xmlns='' width='10' height='10' viewBox='-1 -1 2 2'><circle r='0.5' /></svg>");_x000D_
.x_alternative {_x000D_
  list-style-image: url("data:image/svg+xml;utf8,<svg xmlns='' width='10' height='10' viewBox='-2.2 -2.4 4 4'><circle r='1' /></svg>");_x000D_
<ul class="x">_x000D_
<ul class="x_alternative">_x000D_

Click here for an easy explanation of the viewBox.

c++ array assignment of multiple values

You have to replace the values one by one such as in a for-loop or copying another array over another such as using memcpy(..) or std::copy


for (int i = 0; i < arrayLength; i++) {
    array[i] = newValue[i];

Take care to ensure proper bounds-checking and any other checking that needs to occur to prevent an out of bounds problem.