Programs & Examples On #Rowset

The OLE DB provider "Microsoft.ACE.OLEDB.12.0" for linked server "(null)"

For me, these two things helped on different occasions:

1) If you've just installed the MS Access runtime, reboot the server. Bouncing the database instance isn't enough.

2) As well as making sure the Excel file isn't open, check you haven't got Windows Explorer open with the preview pane switched on - that locks it too.

Import Excel Spreadsheet Data to an EXISTING sql table?

You can copy-paste data from en excel-sheet to an SQL-table by doing so:

  • Select the data in Excel and press Ctrl + C
  • In SQL Server Management Studio right click the table and choose Edit Top 200 Rows
  • Scroll to the bottom and select the entire empty row by clicking on the row header
  • Paste the data by pressing Ctrl + V

Note: Often tables have a first column which is an ID-column with an auto generated/incremented ID. When you paste your data it will start inserting the leftmost selected column in Excel into the leftmost column in SSMS thus inserting data into the ID-column. To avoid that keep an empty column at the leftmost part of your selection in order to skip that column in SSMS. That will result in SSMS inserting the default data which is the auto generated ID.

Furthermore you can skip other columns by having empty columns at the same ordinal positions in the Excel sheet selection as those columns to be skipped. That will make SSMS insert the default value (or NULL where no default value is specified).

how to resolve DTS_E_OLEDBERROR. in ssis

I've just had this issue and my problem was that I had null rows in a csv file, that contained the text "null" rather than being an empty.

How to enable Ad Hoc Distributed Queries

sp_configure 'show advanced options', 1;
sp_configure 'Ad Hoc Distributed Queries', 1;

"Cannot create an instance of OLE DB provider" error as Windows Authentication user

When connecting to SQL Server with Windows Authentication (as opposed to a local SQL Server account), attempting to use a linked server may result in the error message:

Cannot create an instance of OLE DB provider "(OLEDB provider name)"...

The most direct answer to this problem is provided by Microsoft KB 2647989, because "Security settings for the MSDAINITIALIZE DCOM class are incorrect."

The solution is to fix the security settings for MSDAINITIALIZE. In Windows Vista and later, the class is owned by TrustedInstaller, so the ownership of MSDAINITIALIZE must be changed before the security can be adjusted. The KB above has detailed instructions for doing so.

This MSDN blog post describes the reason:

MSDAINITIALIZE is a COM class that is provided by OLE DB. This class can parse OLE DB connection strings and load/initialize the provider based on property values in the connection string. MSDAINITILIAZE is initiated by users connected to SQL Server. If Windows Authentication is used to connect to SQL Server, then the provider is initialized under the logged in user account. If the logged in user is a SQL login, then provider is initialized under SQL Server service account. Based on the type of login used, permissions on MSDAINITIALIZE have to be provided accordingly.

The issue dates back at least to SQL Server 2000; KB 280106 from Microsoft describes the error (see "Message 3") and has the suggested fix of setting the In Process flag for the OLEDB provider.

While setting In Process can solve the immediate problem, it may not be what you want. According to Microsoft,

Instantiating the provider outside the SQL Server process protects the SQL Server process from errors in the provider. When the provider is instantiated outside the SQL Server process, updates or inserts referencing long columns (text, ntext, or image) are not allowed. -- Linked Server Properties doc for SQL Server 2008 R2.

The better answer is to go with the Microsoft guidance and adjust the MSDAINITIALIZE security.

AppFabric installation failed because installer MSI returned with error code : 1603

I've also had a similar problem. The cause was AppFabric generated a scheduled task and it was left behind when it was uninstalled.

the error message in the logs:

"/create /tn "\Microsoft\Windows\AppFabric\Customer Experience Improvement Program\Consolidator" /xml "C:\Program Files\AppFabric 1.1 for Windows Server\Consolidator.xml" Error: ERROR: Cannot create a file when that file already exists."

It can't create the Task because it already exists.

To delete this task.

  • Go to: %SYSTEM32%\Tasks\Microsoft\Windows.
  • Delete the AppFabric Folder.

Then try to re-install it again.

Note: You could also try to delete it from the Task Scheduler GUI but in my case it wasn't shown there.

Escaping backslash in string - javascript

Slightly hacky, but it works:

const input = '\text';_x000D_
const output = JSON.stringify(input).replace(/((^")|("$))/g, "").trim();_x000D_
console.log({ input, output });_x000D_
// { input: '\text', output: '\\text' }

How to call a stored procedure (with parameters) from another stored procedure without temp table

You can create table variable instead of tamp table in procedure A and execute procedure B and insert into temp table by below query.


and you continue operation.

How to loop through Excel files and load them into a database using SSIS package?

I ran into an article that illustrates a method where the data from the same excel sheet can be imported in the selected table until there is no modifications in excel with data types.

If the data is inserted or overwritten with new ones, importing process will be successfully accomplished, and the data will be added to the table in SQL database.

The article may be found here:

Hope it helps.

How can I get the SQL of a PreparedStatement?

If you're using MySQL you can log the queries using MySQL's query log. I don't know if other vendors provide this feature, but chances are they do.

How to BULK INSERT a file into a *temporary* table where the filename is a variable?

You could always construct the #temp table in dynamic SQL. For example, right now I guess you have been trying:



SET @sql = N'BULK INSERT #tmp ...' + @variables;

EXEC master.sys.sp_executesql @sql;


This makes it tougher to maintain (readability) but gets by the scoping issue:


SET @sql = N'CREATE TABLE #tmp(a INT, b INT, c INT);

BULK INSERT #tmp ...' + @variables + ';

SELECT * FROM #tmp;';

EXEC master.sys.sp_executesql @sql;

EDIT 2011-01-12

In light of how my almost 2-year old answer was suddenly deemed incomplete and unacceptable, by someone whose answer was also incomplete, how about:

CREATE TABLE #outer(a INT, b INT, c INT);



CREATE TABLE #inner(a INT, b INT, c INT);

BULK INSERT #inner ...' + @variables + ';

SELECT * FROM #inner;';

INSERT #outer EXEC master.sys.sp_executesql @sql;

How to mount the android img file under linux?

I have found a simple solution:


(with slight adjustments for better readability)

This is for all who want to unpack and modify the original system.img that you can flash using recovery. system.img (which you get from the google factory images for example) represents a sparse ext4 loop mounted file system. It is mounted into /system of your device. Note that this tutorial is for ext4 file system. You may have system image which is yaffs2, for example.

The way it is mounted on Galaxy Nexus:

/dev/block/platform/omap/omap_hsmmc.0/by-name/system /system ext4 ro,relatime,barrier=1,data=ordered 0 0


  • Linux box or virtual machine
  • simg2img and make_ext4fs binaries, which can be downloaded from the linux package android-tools-fsutils


Place your system.img and the 2 binaries in one directory, and make sure the binaries have exec permission.

Part 1 – mount the file-system

mkdir sys
./simg2img system.img sys.raw
sudo mount -t ext4 -o loop sys.raw sys/

Then you have your system partition mounted in ‘sys/’ and you can modify whatever you want in ‘sys/’. For example de-odex apks and framework jars.

Part 2 – create a new flashable system image

sudo ./make_ext4fs -s -l 512M -a system new.img sys/
sudo umount sys
rm -fr sys

Now you can simply type:

fastboot flash system new.img

Match line break with regular expression

You could search for:

<li><a href="#">[^\n]+

And replace with:


Where $0 is the whole match. The exact semantics will depend on the language are you using though.

WARNING: You should avoid parsing HTML with regex. Here's why.

WinError 2 The system cannot find the file specified (Python)

thank you, your first error guides me here and the solution solve mine too!

for permission error, f = open('output', 'w+'), change it into f = open(output+'output', 'w+').

or something else, but the way you are now using is having access to the installation directory of Python which normally in Program Files, and it probably needs administrator permission.

for sure, you could probably running python/your script as administrator to pass permission error though

Convert xlsx file to csv using batch

You need an external tool, in example: - Convert XLSX to CSV.

After installing it, you can use following command in your batch:

"c:\Program Files\Softinterface, Inc\Convert XLS\ConvertXLS.EXE" /S"C:\MyExcelFile.xlsx" /F51 /N"Sheet1" /T"C:\MyExcelFile.CSV" /C6 /M1 /V

Latex Multiple Linebreaks

For programs you are really better off with a verbatim or alltt environment, but if you want a blank line that LaTeX will not bitch about, try

my line of text blah blah blah\\
\mbox{ }\\  %% space followed by newline
new line of text with blank line between 

Python: How to get values of an array at certain index positions?

your code would be

a = [0,88,26,3,48,85,65,16,97,83,91]

ind_pos = [a[1],a[5],a[7]]


you get [88, 85, 16]

Change some value inside the List<T>

This is the way I would do it : saying that "list" is a <List<t>> where t is a class with a Name and a Value field; but of course you can do it with any other class type.

    list = list.Where(c=>c.Name == "height")
        .Select( new t(){Name = c.Name, Value = 30})
        .Union(list.Where(c=> c.Name != "height"))

This works perfectly ! It's a simple linq expression without any loop logic. The only thing you should be aware is that the order of the lines in the result dataset will be different from the order you had in the source dataset. So if sorting is important to you, just reproduce the same order by clauses in the final linq query.

'was not declared in this scope' error

You need to declare y and c outside the scope of the if/else statement. A variable is only valid inside the scope it is declared (and a scope is marked with { })

#include <iostream> 
using namespace std; 
//Using the Gaussian algorithm 
int dayofweek(int date, int month, int year ){ 
int d=date; 
int y, c;
if (month==1||month==2) 
int m=(month+9)%12+1; 
int product=(d+(2.6*m-0.2)+y+y/4+c/4-2*c); 
return product%7; 

int main(){ 
return 0; 

Count number of times value appears in particular column in MySQL

select name, count(*) from table group by name;

i think should do it

input type=file show only button

This HTML code show up only Upload File button

<form action="/action_page.php">
    <input type="button" id="id" value="Upload File"  onclick="document.getElementById('file').click();" />
    <input type="file" style="display:none;" id="file" name="file" onchange="this.form.submit()"/>  

Python logging: use milliseconds in time format

A simple expansion that doesn't require the datetime module and isn't handicapped like some other solutions is to use simple string replacement like so:

import logging
import time

class MyFormatter(logging.Formatter):
    def formatTime(self, record, datefmt=None):
        ct = self.converter(record.created)
        if datefmt:
            if "%F" in datefmt:
                msec = "%03d" % record.msecs
                datefmt = datefmt.replace("%F", msec)
            s = time.strftime(datefmt, ct)
            t = time.strftime("%Y-%m-%d %H:%M:%S", ct)
            s = "%s,%03d" % (t, record.msecs)
        return s

This way a date format can be written however you want, even allowing for region differences, by using %F for milliseconds. For example:

log = logging.getLogger(__name__)

sh = logging.StreamHandler()

fm = MyFormatter(fmt='%(asctime)s-%(levelname)s-%(message)s',datefmt='%H:%M:%S.%F')
sh.setFormatter(fm)"Foo, Bar, Baz")
# 03:26:33.757-INFO-Foo, Bar, Baz

Filling a List with all enum values in Java

I wouldn't use a List in the first places as an EnumSet is more approriate but you can do

List<Something> somethingList = Arrays.asList(Something.values());


List<Something> somethingList =
                 new ArrayList<Something>(EnumSet.allOf(Something.class));

How to get JSON data from the URL (REST API) to UI using jQuery or plain JavaScript?

            url: `//your api url`
            type: "GET",
            dataType: "json",
            success: function(data) {
                jQuery.each(data, function(index, value) {
                        `All you API data is here`

how to use List<WebElement> webdriver

List<WebElement> myElements = driver.findElements(By.xpath("some/path//a"));
        System.out.println("Size of List: "+myElements.size());
        for(WebElement e : myElements) 
            System.out.print("Text within the Anchor tab"+e.getText()+"\t");
            System.out.println("Anchor: "+e.getAttribute("href"));

//NOTE: "//a" will give you all the anchors there on after the point your XPATH has reached.

Waiting until the task finishes

Swift 5 version of the solution

func myCriticalFunction() {
    var value1: String?
    var value2: String?

    let group = DispatchGroup()

    //async operation 1 .default).async { 
        // Network calls or some other async task
        value1 = //out of async task

    //async operation 2 .default).async {
        // Network calls or some other async task
        value2 = //out of async task


    print("Value1 \(value1) , Value2 \(value2)") 

Set the default value in dropdownlist using jQuery

$('#userZipFiles option').prop('selected', function() {
        return this.defaultSelected;

Splitting a table cell into two columns in HTML

You have two options.

  1. Use an extra column in the header, and use <colspan> in your header to stretch a cell for two or more columns.
  2. Insert a <table> with 2 columns inside the td you want extra columns in.

Detach (move) subdirectory into separate Git repository

To add to Paul's answer, I found that to ultimately recover space, I have to push HEAD to a clean repository and that trims down the size of the .git/objects/pack directory.


$ mkdir ...ABC.git
$ cd ...ABC.git
$ git init --bare

After the gc prune, also do:

$ git push ...ABC.git HEAD

Then you can do

$ git clone ...ABC.git

and the size of ABC/.git is reduced

Actually, some of the time consuming steps (e.g. git gc) aren't needed with the push to clean repository, i.e.:

$ git clone --no-hardlinks /XYZ /ABC
$ git filter-branch --subdirectory-filter ABC HEAD
$ git reset --hard
$ git push ...ABC.git HEAD

Inserting line breaks into PDF

Maybe it´s too late but I solved this issue in a very simple way, I am using the Multicell option and the text come from a form, if I use an input field to get the text I can´t insert line breaks in any way, but if use a textarea field, the line breaks in the text area are line breaks in the multicell ... and that´s it, it works even if I use utf8_encode($text) option to preserve accents

How do I add a new class to an element dynamically?

Yes you can - first capture the event using onmouseover, then set the class name using Element.className.

If you like to add or remove classes - use the more convenient Element.classList method.

.active {
  background: red;
<div onmouseover=className="active">
  Hover this!

Increasing the timeout value in a WCF service

In addition to the binding timeouts (which are in Timespans), You may also need this as well. This is in seconds.

    <httpRuntime executionTimeout="600"/><!-- = 10 minutes -->

How do I reference a cell range from one worksheet to another using excel formulas?

I rewrote the code provided by Ninja2k because I didn't like that it looped through cells. For future reference here's a version using arrays instead which works noticeably faster over lots of ranges but has the same result:

Function concat2(useThis As Range, Optional delim As String) As String
    Dim tempValues
    Dim tempString
    Dim numValues As Long
    Dim i As Long, j As Long
    tempValues = useThis
    numValues = UBound(tempValues) * UBound(tempValues, 2)
    ReDim values(1 To numValues)
    For i = UBound(tempValues) To LBound(tempValues) Step -1
        For j = UBound(tempValues, 2) To LBound(tempValues, 2) Step -1
            values(numValues) = tempValues(i, j)
            numValues = numValues - 1
        Next j
    Next i
    concat2 = Join(values, delim)
End Function

I can't help but think there's definitely a better way...

Here are steps to do it manually without VBA which only works with 1d arrays and makes static values instead of retaining the references:

  1. Update cell formula to something like =Sheet2!A1:A15
  2. Hit F9
  3. Remove the curly braces { and }
  4. Place CONCATENATE( at the front of the formula after the = sign and ) at the end of the formula.
  5. Hit enter.

Catching FULL exception message

I keep coming back to these questions trying to figure out where exactly the data I'm interested in is buried in what is truly a monolithic ErrorRecord structure. Almost all answers give piecemeal instructions on how to pull certain bits of data.

But I've found it immensely helpful to dump the entire object with ConvertTo-Json so that I can visually see LITERALLY EVERYTHING in a comprehensible layout.

    try {
    catch {
        Write-Host ($_ | ConvertTo-Json)

Use ConvertTo-Json's -Depth parameter to expand deeper values, but use extreme caution going past the default depth of 2 :P

C# Lambda expressions: Why should I use them?

Anonymous functions and expressions are useful for one-off methods that don't benefit from the extra work required to create a full method.

Consider this example:

 List<string> people = new List<string> { "name1", "name2", "joe", "another name", "etc" };
 string person = people.Find(person => person.Contains("Joe"));


 public string FindPerson(string nameContains, List<string> persons)
     foreach (string person in persons)
         if (person.Contains(nameContains))
             return person;
     return null;

These are functionally equivalent.

git diff file against its last change

If you are fine using a graphical tool this works very well:

gitk <file>

gitk now shows all commits where the file has been updated. Marking a commit will show you the diff against the previous commit in the list. This also works for directories, but then you also get to select the file to diff for the selected commit. Super useful!

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

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

event.preventDefault() vs. return false

This is not, as you've titled it, a "JavaScript" question; it is a question regarding the design of jQuery.

jQuery and the previously linked citation from John Resig (in karim79's message) seem to be the source misunderstanding of how event handlers in general work.

Fact: An event handler that returns false prevents the default action for that event. It does not stop the event propagation. Event handlers have always worked this way, since the old days of Netscape Navigator.

The documentation from MDN explains how return false in an event handler works

What happens in jQuery is not the same as what happens with event handlers. DOM event listeners and MSIE "attached" events are a different matter altogether.

For further reading, see attachEvent on MSDN and the W3C DOM 2 Events documentation.

How to elegantly check if a number is within a range?

I don't know but i use this method:

    public static Boolean isInRange(this Decimal dec, Decimal min, Decimal max, bool includesMin = true, bool includesMax = true ) {

    return (includesMin ? (dec >= min) : (dec > min)) && (includesMax ? (dec <= max) : (dec < max));

And this is the way I can use it:

    public void IsIntoTheRange()
        decimal dec = 54;

        Boolean result = false;

        result = dec.isInRange(50, 60); //result = True

        result = dec.isInRange(55, 60); //result = False

        result = dec.isInRange(54, 60); //result = True

        result = dec.isInRange(54, 60, false); //result = False

        result = dec.isInRange(32, 54, false, false);//result = False

        result = dec.isInRange(32, 54, false);//result = True

CSS: Auto resize div to fit container width

CSS auto-fit container between float:left & float:right divs solved my problem, thanks for your comments.


How to add "active" class to Html.ActionLink in ASP.NET MVC

You can try this: In my case i am loading menu from database based on role based access, Write the code on your every view which menu your want to active based on your view.

<script type="text/javascript">
        $(document).ready(function () {         
            $(' active-menu').removeClass('active active-menu');
            $('a[href="/MgtCustomer/Index"]').closest('li').addClass('active active-menu');

Stick button to right side of div

div {
 display: flex;
 flex-direction: row-reverse;

Remove first 4 characters of a string with PHP

You can use this by php function with substr function

function removeChar($value) {
    $value2 = substr($value, 4); 
    return $value2;

echo removeChar("Dummy Text. Sample Text.");

You get this result: " y Text. Sample Text. "

XAMPP permissions on Mac OS X?

For new XAMPP-VM for Mac OS X,
I change the ownership to daemon user and solve the problem.

For example,

$ chown -R daemon:daemon /opt/lampp/htdocs/hello-laravel/storage

CSS Selector "(A or B) and C"?

If you have this:

<div class="a x">Foo</div>
<div class="b x">Bar</div>
<div class="c x">Baz</div>

And you only want to select the elements which have .x and (.a or .b), you could write:

.x:not(.c) { ... }

but that's convenient only when you have three "sub-classes" and you want to select two of them.

Selecting only one sub-class (for instance .a): .a.x

Selecting two sub-classes (for instance .a and .b): .x:not(.c)

Selecting all three sub-classes: .x

When adding a Javascript library, Chrome complains about a missing source map, why?

In my case, I had to deactivate AdBlock and it worked fine.

What is causing "Unable to allocate memory for pool" in PHP?

Monitor your Cached Files Size (you can use apc.php from apc pecl package) and increase apc.shm_size according to your needs.

This solves the problem.

Cannot perform runtime binding on a null reference, But it is NOT a null reference

This exception is also thrown when a non-existent property is being updated dynamically, using reflection.

If one is using reflection to dynamically update property values, it's worth checking to make sure the passed PropertyName is identical to the actual property.

In my case, I was attempting to update Employee.firstName, but the property was actually Employee.FirstName.

Worth keeping in mind. :)

How to assign name for a screen?

The easiest way use screen with name

screen -S 'name' 'application'
  • Ctrl+a, d = exit and leave application open

Return to screen:

screen -r 'name'

for example using lynx with screen

Create screen:

screen -S lynx lynx

Ctrl+a, d =exit

later you can return with:

screen -r lynx

Creating a thumbnail from an uploaded image

Image Upload with thumbnail generate


function generate_thumb_now($field_name = '',$target_folder ='',$file_name = '', $thumb = FALSE, $thumb_folder = '', $thumb_width = '',$thumb_height = ''){
         //folder path setup
         $target_path = $target_folder;
         $thumb_path = $thumb_folder;   
         //file name setup
    $filename_err = explode(".",$_FILES[$field_name]['name']);
    $filename_err_count = count($filename_err);
    $file_ext = $filename_err[$filename_err_count-1];
     if($file_name != '')
        $fileName = $file_name.'.'.$file_ext;
        $fileName = $_FILES[$field_name]['name'];
    //upload image path
    $upload_image = $target_path.basename($fileName);   
    //upload image
         //thumbnail creation
        if($thumb == TRUE)
            $thumbnail = $thumb_path.$fileName;
            list($width,$height) = getimagesize($upload_image);
            $thumb_create = imagecreatetruecolor($thumb_width,$thumb_height);
                case 'jpg':
                    $source = imagecreatefromjpeg($upload_image);
                case 'jpeg':
                    $source = imagecreatefromjpeg($upload_image);
                case 'png':
                    $source = imagecreatefrompng($upload_image);
                case 'gif':
                    $source = imagecreatefromgif($upload_image);
                    $source = imagecreatefromjpeg($upload_image);
       imagecopyresized($thumb_create, $source, 0, 0, 0, 0, $thumb_width, $thumb_height, $width,$height);
                case 'jpg' || 'jpeg':
                case 'png':
                case 'gif':
        return $fileName;
        return false;
    $upload_img = generate_thumb_now('image','uploads/','',TRUE,'uploads /thumbs/','400','320');

    //full path of the thumbnail image
    $thumb_src = 'uploads/thumbs/'.$upload_img;

    //set success and error messages
    $message = $upload_img?"<span style='color:#008000;'>Image thumbnail created successfully.</span>":"<span style='color:#F00000;'>Some error occurred, please try again.</span>";


    //if form is not submitted, below variable should be blank
    $thumb_src = '';
    $message = '';

    <head>Image upload and generate thumbnail</head>
     <div class="messages"><?php echo $message; ?></div>
      <form method="post" enctype="multipart/form-data">
      <input type="file" name="image"/>
      <input type="submit" name="submit" value="Upload"/>
    <?php if($thumb_src != ''){ ?>
    <div class="gallery">
        <li><img src="<?php echo $thumb_src; ?>" alt=""></li>
    <?php } ?>

AngularJS check if form is valid in controller

Here is another solution

Set a hidden scope variable in your html then you can use it from your controller:

<span style="display:none" >{{ formValid = myForm.$valid}}</span>

Here is the full working example:

angular.module('App', [])_x000D_
.controller('myController', function($scope) {_x000D_
  $scope.userType = 'guest';_x000D_
  $scope.formValid = false;_x000D_'Ctrl init, no form.');_x000D_
  $scope.$watch('myForm', function() {_x000D_'myForm watch');_x000D_
  $scope.isFormValid = function() {_x000D_
    //test the new scope variable_x000D_
    console.log('form valid?: ', $scope.formValid);_x000D_
<!doctype html>_x000D_
<html ng-app="App">_x000D_
 <script type="text/javascript" src=""></script>_x000D_
<form name="myForm" ng-controller="myController">_x000D_
  userType: <input name="input" ng-model="userType" required>_x000D_
  <span class="error" ng-show="myForm.input.$error.required">Required!</span><br>_x000D_
  <tt>userType = {{userType}}</tt><br>_x000D_
  <tt>myForm.input.$valid = {{myForm.input.$valid}}</tt><br>_x000D_
  <tt>myForm.input.$error = {{myForm.input.$error}}</tt><br>_x000D_
  <tt>myForm.$valid = {{myForm.$valid}}</tt><br>_x000D_
  <tt>myForm.$error.required = {{!!myForm.$error.required}}</tt><br>_x000D_
  /*-- Hidden Variable formValid to use in your controller --*/_x000D_
  <span style="display:none" >{{ formValid = myForm.$valid}}</span>_x000D_
  <button ng-click="isFormValid()">Check Valid</button>_x000D_

How do I escape ampersands in batch files?

You can enclose it in quotes, if you supply a dummy first argument.

Note that you need to supply a dummy first argument in this case, as start will treat the first argument as a title for the new console windows, if it is quoted. So the following should work (and does here):

start "" ""

Fatal error: Uncaught Error: Call to undefined function mysql_connect()

Make sure you have not committed a typo as in my case

msyql_fetch_assoc should be mysql

How do I split a multi-line string into multiple lines?

I wish comments had proper code text formatting, because I think @1_CR 's answer needs more bumps, and I would like to augment his answer. Anyway, He led me to the following technique; it will use cStringIO if available (BUT NOTE: cStringIO and StringIO are not the same, because you cannot subclass cStringIO... it is a built-in... but for basic operations the syntax will be identical, so you can do this):

    import cStringIO
    StringIO = cStringIO
except ImportError:
    import StringIO

for line in StringIO.StringIO(variable_with_multiline_string):
print line.strip()

Getting Error - ORA-01858: a non-numeric character was found where a numeric was expected

I added TO_DATE and it resolved issue.

Before modification - due to below condition i got this error


After modification - after adding to_date, issue got resolved.


What represents a double in sql server?


Or if you want to go old-school:


You can also use float(53), but it means the same thing as float.

("real" is equivalent to float(24), not float/float(53).)

The decimal(x,y) SQL Server type is for when you want exact decimal numbers rather than floating point (which can be approximations). This is in contrast to the C# "decimal" data type, which is more like a 128-bit floating point number.

MSSQL's float type is equivalent to the 64-bit double type in .NET. (My original answer from 2011 said there could be a slight difference in mantissa, but I've tested this in 2020 and they appear to be 100% compatible in their binary representation of both very small and very large numbers -- see for my test).

To make things more confusing, a "float" in C# is only 32-bit, so it would be more equivalent in SQL to the real/float(24) type in MSSQL than float/float(53).

In your specific use case... All you need is 5 places after the decimal point to represent latitude and longitude within about one-meter precision, and you only need up to three digits before the decimal point for the degrees. Float(24) or decimal(8,5) will best fit your needs in MSSQL, and using float in C# is good enough, you don't need double. In fact, your users will probably thank you for rounding to 5 decimal places rather than having a bunch of insignificant digits coming along for the ride.

Android translate animation - permanently move View to new position using AnimationListener

I usually prefer to work with deltas in translate animation, since it avoids a lot of confusion.

Try this out, see if it works for you:

TranslateAnimation anim = new TranslateAnimation(0, amountToMoveRight, 0, amountToMoveDown);

anim.setAnimationListener(new TranslateAnimation.AnimationListener() {

    public void onAnimationStart(Animation animation) { }

    public void onAnimationRepeat(Animation animation) { }

    public void onAnimationEnd(Animation animation) 
        FrameLayout.LayoutParams params = (FrameLayout.LayoutParams)view.getLayoutParams();
        params.topMargin += amountToMoveDown;
        params.leftMargin += amountToMoveRight;


Make sure to make amountToMoveRight / amountToMoveDown final

Hope this helps :)

Forgot Oracle username and password, how to retrieve?

The usernames are shown in the dba_users's username column, there is a script you can run called:

alter user username identified by password

You can get more information here -

How to detect DataGridView CheckBox event change?

Here is some code:

private void dgvStandingOrder_CellContentClick(object sender, DataGridViewCellEventArgs e)
    if (dgvStandingOrder.Columns[e.ColumnIndex].Name == "IsSelected" && dgvStandingOrder.CurrentCell is DataGridViewCheckBoxCell)
        bool isChecked = (bool)dgvStandingOrder[e.ColumnIndex, e.RowIndex].EditedFormattedValue;
        if (isChecked == false)
            dgvStandingOrder.Rows[e.RowIndex].Cells["Status"].Value = "";

private void dgvStandingOrder_CellEndEdit(object sender, DataGridViewCellEventArgs e)


private void dgvStandingOrder_CurrentCellDirtyStateChanged(object sender, EventArgs e)
    if (dgvStandingOrder.CurrentCell is DataGridViewCheckBoxCell)

About .bash_profile, .bashrc, and where should alias be written in?

.bash_profile is loaded for a "login shell". I am not sure what that would be on OS X, but on Linux that is either X11 or a virtual terminal.

.bashrc is loaded every time you run Bash. That is where you should put stuff you want loaded whenever you open a new window.

I personally put everything in .bashrc so that I don't have to restart the application for changes to take effect.

Array as session variable

First change the array to a string by using implode() function. E.g $number=array(1,2,3,4,5,...); $stringofnumber=implode("|",$number); then pass the string to a session. e.g $_SESSION['string']=$stringofnumber; so when you go to the page where you want to use the array, just explode your string. e.g $number=explode("|", $_SESSION['string']); finally number is your array but remember to start array on the of each page.

Losing Session State

I was only losing the session which was not a string or integer but a datarow. Putting the data in a serializable object and saving that into the session worked for me.

gdb: how to print the current line or find the current line number?

Command where or frame can be used. where command will give more info with the function name

Can we locate a user via user's phone number in Android?

The answer is: you can't only through sms, i have tried that approach before.

You could fetch the base station IDs, but this won't help you a lot without the location of the base station itself and this informations are really hard to retrieve from the providers.

I have looked through the 3 apps you have listed in your question:

  1. The App uses WiFi and GPRS location service, quite the same approach as Google uses on the phone. phonesavvy maybe has a base station location database or uses a database retrieved e.g. from OpenStreetMap or some similar crowd-based project.
  2. The app analyzes just the number for country code and city code. No location there.
  3. Dito.

Lambda expression to convert array/List of String to array/List of Integers

In addition - control when string array doesn't have elements: -> (t != null)&&!("".equals(t))).map(func).toArray(generator) 

How do I change Bootstrap 3 column order on mobile layout?

October 2017

I would like to add another Bootstrap 4 solution. One that worked for me.

The CSS "Order" property, combined with a media query, can be used to re-order columns when they get stacked in smaller screens.

Something like this:

@media only screen and (max-width: 768px) {
    #first {
        order: 2;
    #second {
        order: 4;
    #third {
        order: 1;
    #fourth {
        order: 3;

CodePen Link:

Adjust the screen size and you'll see the columns get stacked in a different order.

I'll tie this in with the original poster's question. With CSS, the navbar, sidebar, and content can be targeted and then order properties applied within a media query.

Creating watermark using html and css

To make it fixed: Try this way,


<div class="body">This is a sample body This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample bodyThis is a sample bodyThis is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    This is a sample body
    <div class="watermark">
           Sample Watermark
    This is a sample body
    This is a sample bodyThis is a sample bodyThis is a sample body

.watermark {
    opacity: 0.5;
    color: BLACK;
    position: fixed;
    top: auto;
    left: 80%;

To use absolute:

.watermark {
    opacity: 0.5;
    color: BLACK;
    position: absolute;
    bottom: 0;
    right: 0;


Static variables in JavaScript

If you are using the new class syntax then you can now do the following:

    class MyClass {_x000D_
      static get myStaticVariable() {_x000D_
        return "some static variable";_x000D_
    aMyClass = new MyClass();_x000D_
    console.log(aMyClass.myStaticVariable, "is undefined");

This effectively creates a static variable in JavaScript.

Could not find module FindOpenCV.cmake ( Error in configuration process)

On my Fedora machine, when I typed "make" I got an error saying it could not find "cv.h". I fixed this by modifying my "OpenCVConfig.cmake" file.


SET(OpenCV_INCLUDE_DIRS "${OpenCV_INSTALL_PATH}/include/opencv;${OpenCV_INSTALL_PATH}/include")



SET(OpenCV_INCLUDE_DIRS "/usr/include/opencv;/usr/include/opencv2")

SET(OpenCV_LIB_DIR "/usr/lib64")

How to select option in drop down using Capybara

It is not a direct answer, but you can (if your server permit):

1) Create a model for your Organization; extra: It will be easier to populate your HTML.

2) Create a factory (FactoryGirl) for your model;

3) Create a list (create_list) with the factory;

4) 'pick' (sample) a Organization from the list with:

# Random select
option = Organization.all.sample 

# Select the FIRST(0) by id
option = Organization.all[0] 

# Select the SECOND(1) after some restriction
option = Organization.where(some_attr: some_value)[2]
option = Organization.where("some_attr OP some_value")[2] #OP is "=", "<", ">", so on... 

'cannot find or open the pdb file' Visual Studio C++ 2013

Working with VS 2013. Try the following

Tools -> Options -> Debugging -> Output Window -> Module Load Messages -> Off

It will disable the display of modules loaded.

What are the uses of the exec command in shell scripts?

Just to augment the accepted answer with a brief newbie-friendly short answer, you probably don't need exec.

If you're still here, the following discussion should hopefully reveal why. When you run, say,

sh -c 'command'

you run a sh instance, then start command as a child of that sh instance. When command finishes, the sh instance also finishes.

sh -c 'exec command'

runs a sh instance, then replaces that sh instance with the command binary, and runs that instead.

Of course, both of these are useless in this limited context; you simply want


There are some fringe situations where you want the shell to read its configuration file or somehow otherwise set up the environment as a preparation for running command. This is pretty much the sole situation where exec command is useful.

ENVIRONMENT=$(some complex task)
exec command

This does some stuff to prepare the environment so that it contains what is needed. Once that's done, the sh instance is no longer necessary, and so it's a (minor) optimization to simply replace the sh instance with the command process, rather than have sh run it as a child process and wait for it, then exit as soon as it finishes.

Similarly, if you want to free up as much resources as possible for a heavyish command at the end of a shell script, you might want to exec that command as an optimization.

If something forces you to run sh but you really wanted to run something else, exec something else is of course a workaround to replace the undesired sh instance (like for example if you really wanted to run your own spiffy gosh instead of sh but yours isn't listed in /etc/shells so you can't specify it as your login shell).

The second use of exec to manipulate file descriptors is a separate topic. The accepted answer covers that nicely; to keep this self-contained, I'll just defer to the manual for anything where exec is followed by a redirect instead of a command name.

What's the difference between commit() and apply() in SharedPreferences

Use apply().

It writes the changes to the RAM immediately and waits and writes it to the internal storage(the actual preference file) after. Commit writes the changes synchronously and directly to the file.

In JavaScript can I make a "click" event fire programmatically for a file input element?

it's not impossible:

var evObj = document.createEvent('MouseEvents');
evObj.initMouseEvent('click', true, true, window);  
setTimeout(function(){ document.getElementById('input_field_id').dispatchEvent(evObj); },100);

But somehow it works only if this is in a function which was called via a click-event.

So you might have following setup:


<div onclick="openFileChooser()" class="some_fancy_stuff">Click here to open image chooser</div>
<input type="file" id="input_img">


    function openFileChooser() {
      var evObj = document.createEvent('MouseEvents');
      evObj.initMouseEvent('click', true, true, window);  

Multi-character constant warnings

Simplest C/C++ any compiler/standard compliant solution, was mentioned by @leftaroundabout in comments above:

int x = *(int*)"abcd";

Or a bit more specific:

int x = *(int32_t*)"abcd";

One more solution, also compliant with C/C++ compiler/standard since C99 (except clang++, which has a known bug):

int x = ((union {char s[5]; int number;}){"abcd"}).number;

/* just a demo check: */
printf("x=%d stored %s byte first\n", x, x==0x61626364 ? "MSB":"LSB");

Here anonymous union is used to give a nice symbol-name to the desired numeric result, "abcd" string is used to initialize the lvalue of compound literal (C99).

CSS opacity only to background color, not the text on it?

A great way to do this would be to use CSS 3 indeed.

Create a div width a class - e.g. supersizer on top of your page:

Then set following CSS properties:

  .supersizer {_x000D_
    background: url("") no-repeat center center fixed;_x000D_
    width: 100%;_x000D_
    height: 100%;_x000D_
    position: fixed;_x000D_
    z-index: -1;_x000D_
    opacity: 0.5;_x000D_
    -webkit-background-size: cover;_x000D_
    -moz-background-size: cover;_x000D_
    -o-background-size: cover;_x000D_
    background-size: cover;_x000D_
    top: 0;_x000D_
<div class="supersizer"></div>

php: check if an array has duplicates

I'm using this:

    echo("all values are unique");
    echo("there's dupe values");

I don't know if it's the fastest but works pretty good so far

reactjs - how to set inline style of backgroundcolor?

Your quotes are in the wrong spot. Here's a simple example:

<div style={{backgroundColor: "#FF0000"}}>red</div>

ProcessStartInfo hanging on "WaitForExit"? Why?

I know that this is supper old but, after reading this whole page none of the solutions was working for me, although I didn't try Muhammad Rehan as the code was a little hard to follow, although I guess he was on the right track. When I say it didn't work that's not entirely true, sometimes it would work fine, I guess it is something to do with the length of the output before an EOF mark.

Anyway, the solution that worked for me was to use different threads to read the StandardOutput and StandardError and write the messages.

        StreamWriter sw = null;
        var queue = new ConcurrentQueue<string>();

        var flushTask = new System.Timers.Timer(50);
        flushTask.Elapsed += (s, e) =>
            while (!queue.IsEmpty)
                string line = null;
                if (queue.TryDequeue(out line))

        using (var process = new Process())
                process.StartInfo.FileName = @"...";
                process.StartInfo.Arguments = $"...";
                process.StartInfo.UseShellExecute = false;
                process.StartInfo.RedirectStandardOutput = true;
                process.StartInfo.RedirectStandardError = true;


                var outputRead = Task.Run(() =>
                    while (!process.StandardOutput.EndOfStream)

                var errorRead = Task.Run(() =>
                    while (!process.StandardError.EndOfStream)

                var timeout = new TimeSpan(hours: 0, minutes: 10, seconds: 0);

                if (Task.WaitAll(new[] { outputRead, errorRead }, timeout) &&
                    if (process.ExitCode != 0)
                        throw new Exception($"Failed run... blah blah");
                    throw new Exception($"process timed out after waiting {timeout}");
            catch (Exception e)
                throw new Exception($"Failed to succesfully run the process.....", e);

Hope this helps someone, who thought this could be so hard!

Getting the textarea value of a ckeditor textarea with javascript

Well. You asked about get value from textarea but in your example you are using a input. Anyways, here we go:

$("#CampaignTitle").bind("keyup", function()

If you really wanted a textarea change your input type text to this

<textarea id="CampaignTitle"></textarea>

Hope it helps.

How do you determine what SQL Tables have an identity column programmatically

This query seems to do the trick:

SELECT AS table_name, AS column_name
FROM sys.columns JOIN sys.objects 
    ON sys.columns.object_id=sys.objects.object_id
    sys.objects.type in (N'U')

mysql update multiple columns with same now()

You can store the value of a now() in a variable before running the update query and then use that variable to update both the fields last_update and last_monitor.

This will ensure the now() is executed only once and same value is updated on both columns you need.

Set style for TextView programmatically

I have only tested with EditText but you can use the method

public void setBackgroundResource (int resid)

to apply a style defined in an XML file.

Sine this method belongs to View I believe it will work with any UI element.


Run Jquery function on window events: load, resize, and scroll?

You can bind listeners to one common functions -

$(window).bind("load resize scroll",function(e){
  // do stuff

Or another way -





Alternatively, instead of using .bind() you can use .on() as bind directly maps to on(). And maybe .bind() won't be there in future jquery versions.





Android open pdf file

As of API 24, sending a file:// URI to another app will throw a FileUriExposedException. Instead, use FileProvider to send a content:// URI:

public File getFile(Context context, String fileName) {
    if (!Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
        return null;

    File storageDir = context.getExternalFilesDir(null);
    return new File(storageDir, fileName);

public Uri getFileUri(Context context, String fileName) {
    File file = getFile(context, fileName);
    return FileProvider.getUriForFile(context, BuildConfig.APPLICATION_ID + ".provider", file);

You must also define the FileProvider in your manifest:

        android:resource="@xml/file_paths" />

Example file_paths.xml:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="">
    <external-files-path name="name" path="path" />

Replace "name" and "path" as appropriate.

To give the PDF viewer access to the file, you also have to add the FLAG_GRANT_READ_URI_PERMISSION flag to the intent:

private void displayPdf(String fileName) {
    Uri uri = getFileUri(this, fileName);

    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setDataAndType(uri, "application/pdf");

    // FLAG_GRANT_READ_URI_PERMISSION is needed on API 24+ so the activity opening the file can read it

    if (intent.resolveActivity(getPackageManager()) == null) {
        // Show an error
    } else {

See the FileProvider documentation for more details.

How can I enter latitude and longitude in Google Maps?

It's actually fairly easy, just enter it as a latitude,longitude pair, ie 46.38S,115.36E (which is in the middle of the ocean). You'll want to convert it to decimal though (divide the minutes portion by 60 and add it to the degrees [I've done that with your example]).

How do I send a cross-domain POST request via JavaScript?

  1. Create an iFrame,
  2. put a form in it with Hidden inputs,
  3. set the form's action to the URL,
  4. Add iframe to document
  5. submit the form


 var ifr = document.createElement('iframe');
 var frm = document.createElement('form');
 frm.setAttribute("action", "yoururl");
 frm.setAttribute("method", "post");

 // create hidden inputs, add them
 // not shown, but similar (create, setAttribute, appendChild)


You probably want to style the iframe, to be hidden and absolutely positioned. Not sure cross site posting will be allowed by the browser, but if so, this is how to do it.

How to deal with a slow SecureRandom generator?

Something else to look at is the property securerandom.source in file lib/security/

There may be a performance benefit to using /dev/urandom rather than /dev/random. Remember that if the quality of the random numbers is important, don't make a compromise which breaks security.

Disabling browser caching for all browsers from ASP.NET

See also How to prevent google chrome from caching my inputs, esp hidden ones when user click back? without which Chrome might reload but preserve the previous content of <input> elements -- in other words, use autocomplete="off".

Creating SVG elements dynamically with javascript inside HTML

Add this to html:

<svg id="mySVG" xmlns="" xmlns:xlink=""/>

Try this function and adapt for you program:

var svgNS = "";  

function createCircle()
    var myCircle = document.createElementNS(svgNS,"circle"); //to create a circle. for rectangle use "rectangle"


What are the Android SDK build-tools, platform-tools and tools? And which version should be used?

You can find details about these in this Android - Command Line Tools


SDK Tools:

  1. Android SDK Manager (sdkmanager)
  2. AVD Manager (avdmanager)
  3. Dalvik Debug Monitor Server (ddms)

Build Tools:

  1. signer
  2. proGuard
  3. zipalign
  4. jobb

Platform Tools:

  1. adb
  2. aidl, aapt, dexdump, and dx
  3. bmgr
  4. logcat

FPDF utf-8 encoding (HOW-TO)

There is an extension of FPDF called mPDF that allows Unicode fonts.

How to parse json string in Android?

Below is the link which guide in parsing JSON string in android.

Also according to your json string code snippet must be something like this:-

JSONObject mainObject = new JSONObject(yourstring);

JSONObject universityObject = mainObject.getJSONObject("university");
JSONString name = universityObject.getString("name");  
JSONString url = universityObject.getString("url");

Following is the API reference for JSOnObject:

Same for other object.

OTP (token) should be automatically read from the message

I implemented something of that such. But, here is what I did when the message comes in, I retrieve only the six digit code, bundle it in an intent and send it to the activity or fragment needing it and verifies the code. The example shows you the way to get the sms already. Look at the code below for illustration on how to send using LocalBrodcastManager and if your message contains more texts E.g Greetings, standardize it to help you better. E.g "Your verification code is: 84HG73" you can create a regex pattern like this ([0-9]){2}([A-Z]){2}([0-9]){2} which means two ints, two [capital] letters and two ints. Good Luck!

After discarding all un needed info from the message

 Intent intent = new Intent("AddedItem");
 intent.putExtra("items", code);

And the Fragment/Activity receiving it

public void onResume() {
    LocalBroadcastManager.getInstance(getActivity()).registerReceiver(receiver, new IntentFilter("AddedItem"));

public void onPause() {

And the code meant to handle the payload you collected

 private BroadcastReceiver receiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction()) {
            final String message = intent.getStringExtra("message");
            //Do whatever you want with the code here

Does that help a little bit. I did it better by using Callbacks

Eclipse/Java code completion not working

Check the lib of your project. It may be that you have include two such jar files in which same class is available or say one class in code can be refrenced in two jar files. In such case also eclipse stops assisting code as it is totally confused.

Better way to check this is go to the file where assist is not working and comment all imports there, than add imports one by one and check at each import if code-assist is working or not.You can easily find the class with duplicate refrences.

Error executing command 'ant' on Mac OS X 10.9 Mavericks when building for Android with PhoneGap/Cordova

I encountered the same issue when trying to use Cordova. Turns out I already had brew, try which brew, but it was outdated. So, I had to update it first:

  1. Update brew: brew update
  2. Install Apache Ant: brew install ant

In Python, how do I loop through the dictionary and change the value if it equals something?

for k, v in mydict.iteritems():
    if v is None:
        mydict[k] = ''

In a more general case, e.g. if you were adding or removing keys, it might not be safe to change the structure of the container you're looping on -- so using items to loop on an independent list copy thereof might be prudent -- but assigning a different value at a given existing index does not incur any problem, so, in Python 2.any, it's better to use iteritems.

In Python3 however the code gives AttributeError: 'dict' object has no attribute 'iteritems' error. Use items() instead of iteritems() here.

Refer to this post.

Pass variables to Ruby script via command line

Unfortunately, Ruby does not support such passing mechanism as e.g. AWK:

> awk -v a=1 'BEGIN {print a}'
> 1

It means you cannot pass named values into your script directly.

Using cmd options may help:

> ruby script.rb val_0 val_1 val_2

# script.rb
puts ARGV[0] # => val_0
puts ARGV[1] # => val_1
puts ARGV[2] # => val_2

Ruby stores all cmd arguments in the ARGV array, the scriptname itself can be captured using the $PROGRAM_NAME variable.

The obvious disadvantage is that you depend on the order of values.

If you need only Boolean switches use the option -s of the Ruby interpreter:

> ruby -s -e 'puts "So do I!" if $agreed' -- -agreed
> So do I!

Please note the -- switch, otherwise Ruby will complain about a nonexistent option -agreed, so pass it as a switch to your cmd invokation. You don't need it in the following case:

> ruby -s script_with_switches.rb -agreed
> So do I!

The disadvantage is that you mess with global variables and have only logical true/false values.

You can access values from environment variables:

> FIRST_NAME='Andy Warhol' ruby -e 'puts ENV["FIRST_NAME"]'
> Andy Warhol

Drawbacks are present here to, you have to set all the variables before the script invocation (only for your ruby process) or to export them (shells like BASH):

> export FIRST_NAME='Andy Warhol'
> ruby -e 'puts ENV["FIRST_NAME"]'

In the latter case, your data will be readable for everybody in the same shell session and for all subprocesses, which can be a serious security implication.

And at least you can implement an option parser using getoptlong and optparse.

Happy hacking!

How to remove outliers in boxplot in R?

See ?boxplot for all the help you need.

 outline: if ‘outline’ is not true, the outliers are not drawn (as
          points whereas S+ uses lines).


And for extending the range of the whiskers and suppressing the outliers inside this range:

   range: this determines how far the plot whiskers extend out from the
          box.  If ‘range’ is positive, the whiskers extend to the most
          extreme data point which is no more than ‘range’ times the
          interquartile range from the box. A value of zero causes the
          whiskers to extend to the data extremes.

# change the value of range to change the whisker length

Linux configure/make, --prefix?

Do configure --help and see what other options are available.

It is very common to provide different options to override different locations. By standard, --prefix overrides all of them, so you need to override config location after specifying the prefix. This course of actions usually works for every automake-based project.

The worse case scenario is when you need to modify the configure script, or even worse, generated makefiles and config.h headers. But yeah, for Xfce you can try something like this:

./configure --prefix=/home/me/somefolder/mybuild/output/target --sysconfdir=/etc 

I believe that should do it.

What is the easiest way to ignore a JPA field during persistence?

use @Transient to make JPA ignoring the field.

but! Jackson will not serialize that field as well. to solve just add @JsonProperty

an example

private boolean locked;

Split string, convert ToList<int>() in one line

also you can use this Extension method

public static List<int> SplitToIntList(this string list, char separator = ',')
    return list.Split(separator).Select(Int32.Parse).ToList();


var numberListString = "1, 2, 3, 4";
List<int> numberList = numberListString.SplitToIntList(',');

Update UI from Thread in Android

Use the AsyncTask class (instead of Runnable). It has a method called onProgressUpdate which can affect the UI (it's invoked in the UI thread).

How to find Google's IP address?

nslookup is the easiest way. Works on Linux and Windows.

If your issue is that your DNS server is not returning a response for, use a different DNS server, such as a public one. For instance, you could do:


For a more thorough solution to getting around annoying Internet filters, look into using Tor.

How to include another XHTML in XHTML using JSF 2.0 Facelets?

Included page:

<!-- opening and closing tags of included page -->
<ui:composition ...>

Including page:

<!--the inclusion line in the including page with the content-->
<ui:include src="yourFile.xhtml"/>
  • You start your included xhtml file with ui:composition as shown above.
  • You include that file with ui:include in the including xhtml file as also shown above.

How to solve error: "Clock skew detected"?

I am going to answer my own question.

I added the following lines of code to my Makefile and it fixed the "clock skew" problem:

    find . -type f | xargs touch
    rm -rf $(OBJS)

What is special about /dev/tty?

/dev/tty is a synonym for the controlling terminal (if any) of the current process. As jtl999 says, it's a character special file; that's what the c in the ls -l output means.

man 4 tty or man -s 4 tty should give you more information, or you can read the man page online here.

Incidentally, pwd > /dev/tty doesn't necessarily print to the shell's stdout (though it is the pwd command's standard output). If the shell's standard output has been redirected to something other than the terminal, /dev/tty still refers to the terminal.

You can also read from /dev/tty, which will normally read from the keyboard.

Character reading from file in Python


Reading Unicode from a file is therefore simple:

import codecs
with'unicode.rst', encoding='utf-8') as f:
    for line in f:
        print repr(line)

It's also possible to open files in update mode, allowing both reading and writing:

with'test', encoding='utf-8', mode='w+') as f:
    f.write(u'\u4500 blah blah blah\n')
    print repr(f.readline()[:1])

EDIT: I'm assuming that your intended goal is just to be able to read the file properly into a string in Python. If you're trying to convert to an ASCII string from Unicode, then there's really no direct way to do so, since the Unicode characters won't necessarily exist in ASCII.

If you're trying to convert to an ASCII string, try one of the following:

  1. Replace the specific unicode chars with ASCII equivalents, if you are only looking to handle a few special cases such as this particular example

  2. Use the unicodedata module's normalize() and the string.encode() method to convert as best you can to the next closest ASCII equivalent (Ref

    >>> teststr
    u'I don\xe2\x80\x98t like this'
    >>> unicodedata.normalize('NFKD', teststr).encode('ascii', 'ignore')
    'I donat like this'

Delete all the records

If you want to reset your table, you can do

truncate table TableName

truncate needs privileges, and you can't use it if your table has dependents (another tables that have FK of your table,

libxml install error using pip

I solved this issue by increasing my server ram.

I was running only 512 MB and when I upgraded to 1 GB I had no problem.

I also installed every package manually prior to this in an attempt to fix the problem, but I'm not sure whether this is a necessary step.

Wait until boolean value changes it state

This is not my prefered way to do this, cause of massive CPU consumption.

If that is actually your working code, then just keep it like that. Checking a boolean once a second causes NO measurable CPU load. None whatsoever.

The real problem is that the thread that checks the value may not see a change that has happened for an arbitrarily long time due to caching. To ensure that the value is always synchronized between threads, you need to put the volatile keyword in the variable definition, i.e.

private volatile boolean value;

Note that putting the access in a synchronized block, such as when using the notification-based solution described in other answers, will have the same effect.

How to get the selected row values of DevExpress XtraGrid?

For VB.Net

CType(GridControl1.MainView, GridView).GetFocusedRow()

For C#


example bind data by linq so use

Dim selRow As CUSTOMER = CType(GridControl1.MainView, GridView).GetFocusedRow()

Gradle version 2.2 is required. Current version is 2.10

  1. Open
  2. Change this line:



  1. Go to build.gradle (Project: your_app_name)
  2. Change this line

     classpath ''

to this

     classpath ''


     classpath ''
  1. Don't click Sync Now
  2. From menu choose File -> Invalidate Caches/Restart...
  3. Choose first option: Invalidate and Restart

Android Studio would restart. After this, it should work normally

Hope it help

align textbox and text/labels in html?

I like to set the 'line-height' in the css for the divs to get them to line up properly. Here is an example of how I do it using asp and css:


<div id="profileRow1">
    <div id="profileRow1Col1" class="righty">
        <asp:Label ID="lblCreatedDateLabel" runat="server" Text="Date Created:"></asp:Label><br />
        <asp:Label ID="lblLastLoginDateLabel" runat="server" Text="Last Login Date:"></asp:Label><br />
        <asp:Label ID="lblUserIdLabel" runat="server" Text="User ID:"></asp:Label><br />
        <asp:Label ID="lblUserNameLabel" runat="server" Text="Username:"></asp:Label><br />
        <asp:Label ID="lblFirstNameLabel" runat="server" Text="First Name:"></asp:Label><br />
        <asp:Label ID="lblLastNameLabel" runat="server" Text="Last Name:"></asp:Label><br />
    <div id="profileRow1Col2">
        <asp:Label ID="lblCreatedDate" runat="server" Text="00/00/00 00:00:00"></asp:Label><br />
        <asp:Label ID="lblLastLoginDate" runat="server" Text="00/00/00 00:00:00"></asp:Label><br />
        <asp:Label ID="lblUserId" runat="server" Text="UserId"></asp:Label><br />
        <asp:TextBox ID="txtUserName" runat="server"></asp:TextBox><br />
        <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox><br />
        <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox><br />

And here is the code in the CSS file to make all of the above fields look nice and neat:

#profileRow1Col1{float:left; width:25%; margin-right:20px;}
#profileRow1Col2{float:left; width:25%;}

you can basically pull everything but the DIV tags and replace with your own content.

Trust me when I say it looks aligned the way the image in the original post does!

I would post a screenshot but Stack wont let me: Oops! Your edit couldn't be submitted because: We're sorry, but as a spam prevention mechanism, new users aren't allowed to post images. Earn more than 10 reputation to post images.


Dictionary of dictionaries in Python?

Using collections.defaultdict is a big time-saver when you're building dicts and don't know beforehand which keys you're going to have.

Here it's used twice: for the resulting dict, and for each of the values in the dict.

import collections

def aggregate_names(errors):
    result = collections.defaultdict(lambda: collections.defaultdict(list))
    for real_name, false_name, location in errors:
    return result

Combining this with your code:

dictionary = aggregate_names(previousFunction(string))

Or to test:

    ('Fred', 'Frad', 123),
    ('Jim', 'Jam', 100),
    ('Fred', 'Frod', 200),
    ('Fred', 'Frad', 300)]
print aggregate_names(EXAMPLES)

Return Boolean Value on SQL Select Statement

DECLARE @isAvailable      BIT = 0;

IF EXISTS(SELECT 1  FROM [User] WHERE (UserID = 20070022))
 SET @isAvailable = 1

initially isAvailable boolean value is set to 0

Pip install - Python 2.7 - Windows 7

you have to first download the and then run the command :


How to Use Content-disposition for force a file to download to the hard drive?

On the HTTP Response where you are returning the PDF file, ensure the content disposition header looks like:

Content-Disposition: attachment; filename=quot.pdf;

See content-disposition on the wikipedia MIME page.

How to make HTML input tag only accept numerical values?

I use this for Zip Codes, quick and easy.

<input type="text" id="zip_code" name="zip_code" onkeypress="return event.charCode > 47 && event.charCode < 58;" pattern="[0-9]{5}" required></input>

SQL to Entity Framework Count Group-By

with EF 6.2 it worked for me

  var query = context.People
               .GroupBy(p => new {})
               .Select(g => new { name =, count = g.Count() });

Use of Java's Collections.singletonList()?

Here's one view on the singleton methods:

I have found these various "singleton" methods to be useful for passing a single value to an API that requires a collection of that value. Of course, this works best when the code processing the passed-in value does not need to add to the collection.

Deploying my application at the root in Tomcat

I know that my answer is kind of overlapping with some of the other answer, but this is a complete solution that has some advantages. This works on Tomcat 8:

  1. The main application is served from the root
  2. The deployment of war files through the web interface is maintained.
  3. The main application will run on port 80 while only the admins have access to the managment folders (I realize that *nix systems require superuser for binding to 80, but on windows this is not an issue).

This means that you only have to restart the tomcat once, and after updated war files can be deployed without a problem.

Step 1: In the server.xml file, find the connector entry and replace it with:

    redirectPort="8443" />

    redirectPort="8443" />

Step 2: Define contexts within the <Host ...> tag:

<Context path="/" docBase="CAS">
<Context path="/ROOT" docBase="ROOT">
<Context path="/manager" docBase="manager" privileged="true">
<Context path="/host-manager" docBase="host-manager" privileged="true">

Note that I addressed all apps in the webapp folder. The first effectively switch the root and the main app from position. ROOT is now on and the the main application is on The webapps that are password protected require the privileged="true" attribute.

When you deploy a CAS.war file that matches with the root (<Context path="/" docBase="CAS"> you have to reload that one in the admin panel as it does not refresh with the deployment.

Do not include the <Context path="/CAS" docBase="CAS"> in your contexts as it disables the manager option to deploy war files. This means that you can access the app in two ways: and

Step 3: In order to prevent unwanted access to the root and manager folder, add a valve to those context tags like this:

<Context path="/manager" docBase="manager" privileged="true">
    <Valve className="org.apache.catalina.valves.RemoteAddrValve"

This essentially limits access to the admin web app folder to people from my own domain (fake IP address) and localhost when they use the default port 8080 and maintains the ability to dynamically deploy the war files through the web interface.

If you want to use this for multiple apps that are using different IP addresses, you can add the IP address to the connector (address="").

If you want to run multiple web apps from the root, you can duplicate the Service tag (use a different name for the second) and change the docbase of the <Context path="/" docBase="CAS"> to for example <Context path="/" docBase="ICR">.

C++ convert hex string to signed integer

Try this. This solution is a bit risky. There are no checks. The string must only have hex values and the string length must match the return type size. But no need for extra headers.

char hextob(char ch)
    if (ch >= '0' && ch <= '9') return ch - '0';
    if (ch >= 'A' && ch <= 'F') return ch - 'A' + 10;
    if (ch >= 'a' && ch <= 'f') return ch - 'a' + 10;
    return 0;
template<typename T>
T hextot(char* hex)
    T value = 0;
    for (size_t i = 0; i < sizeof(T)*2; ++i)
        value |= hextob(hex[i]) << (8*sizeof(T)-4*(i+1));
    return value;


int main()
    char str[4] = {'f','f','f','f'};
    std::cout << hextot<int16_t>(str)  << "\n";

Note: the length of the string must be divisible by 2

GROUP BY having MAX date

There's no need to group in that subquery... a where clause would suffice:

SELECT * FROM tblpm n
WHERE date_updated=(SELECT MAX(date_updated)
    FROM tblpm WHERE control_number=n.control_number)

Also, do you have an index on the 'date_updated' column? That would certainly help.

Write variable to file, including name

Is something like this what you're looking for?

def write_vars_to_file(f, **vars):
    for name, val in vars.items():
        f.write("%s = %s\n" % (name, repr(val)))


>>> import sys
>>> write_vars_to_file(sys.stdout, dict={'one': 1, 'two': 2})
dict = {'two': 2, 'one': 1}

Firefox and SSL: sec_error_unknown_issuer

June 2014:

This is the configuration I used and it working fine after banging my head on the wall for some days. I use Express 3.4 (I think is the same for Express 4.0)

var privateKey  = fs.readFileSync('helpers/sslcert/key.pem', 'utf8');
var certificate = fs.readFileSync('helpers/sslcert/csr.pem', 'utf8');

files = ["COMODORSADomainValidationSecureServerCA.crt",

ca = (function() {
  var _i, _len, _results;

  _results = [];
  for (_i = 0, _len = files.length; _i < _len; _i++) {
    file = files[_i];
    _results.push(fs.readFileSync("helpers/sslcert/" + file));
  return _results;

var credentials = {ca:ca, key: privateKey, cert: certificate};

// process.env.PORT : Heroku Config environment
var port = process.env.PORT || 4000;

var app = express();
var server = http.createServer(app).listen(port, function() {
        console.log('Express HTTP server listening on port ' + server.address().port);
https.createServer(credentials, app).listen(3000, function() {
        console.log('Express HTTPS server listening on port ' + server.address().port);

// redirect all http requests to https
app.use(function(req, res, next) {
  if(! {
    return res.redirect(['', req.url].join(''));

Then I redirected the 80 and 443 ports:

sudo iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 4000
sudo iptables -t nat -A PREROUTING -p tcp --dport 443 -j REDIRECT --to-ports 3000

As you can see after checking my certifications I have 4 [0,1,2,3]:

openssl s_client -connect -showcerts | grep "^ "

ubuntu@ip-172-31-5-134:~$ openssl s_client -connect -showcerts | grep "^ "
depth=3 C = SE, O = AddTrust AB, OU = AddTrust External TTP Network, CN = AddTrust External CA Root
verify error:num=19:self signed certificate in certificate chain
verify return:0
 0 s:/OU=Domain Control Validated/OU=PositiveSSL/
   i:/C=GB/ST=Greater Manchester/L=Salford/O=COMODO CA Limited/CN=COMODO RSA Domain Validation Secure Server CA
 1 s:/C=GB/ST=Greater Manchester/L=Salford/O=COMODO CA Limited/CN=COMODO RSA Domain Validation Secure Server CA
   i:/C=GB/ST=Greater Manchester/L=Salford/O=COMODO CA Limited/CN=COMODO RSA Certification Authority
 2 s:/C=GB/ST=Greater Manchester/L=Salford/O=COMODO CA Limited/CN=COMODO RSA Certification Authority
   i:/C=SE/O=AddTrust AB/OU=AddTrust External TTP Network/CN=AddTrust External CA Root
 3 s:/C=SE/O=AddTrust AB/OU=AddTrust External TTP Network/CN=AddTrust External CA Root
   i:/C=SE/O=AddTrust AB/OU=AddTrust External TTP Network/CN=AddTrust External CA Root
    Protocol  : TLSv1.1
    Cipher    : AES256-SHA
    Session-ID: 8FDEAEE92ED20742.....3E7D80F93226142DD
    Master-Key: C9E4AB966E41A85EEB7....4D73C67088E1503C52A9353C8584E94
    Key-Arg   : None
    PSK identity: None
    PSK identity hint: None
    SRP username: None
    TLS session ticket lifetime hint: 300 (seconds)
    TLS session ticket:
    0000 - 7c c8 36 80 95 4d 4c 47-d8 e3 ca 2e 70 a5 8f ac   |.6..MLG....p...
    0010 - 90 bd 4a 26 ef f7 d6 bc-4a b3 dd 8f f6 13 53 e9   ..J&..........S.
    0020 - f7 49 c6 48 44 26 8d ab-a8 72 29 c8 15 73 f5 79   .I.HD&.......s.y
    0030 - ca 79 6a ed f6 b1 7f 8a-d2 68 0a 52 03 c5 84 32   .yj........R...2
    0040 - be c5 c8 12 d8 f4 36 fa-28 4f 0e 00 eb d1 04 ce   ........(.......
    0050 - a7 2b d2 73 df a1 8b 83-23 a6 f7 ef 6e 9e c4 4c   .+.s...........L
    0060 - 50 22 60 e8 93 cc d8 ee-42 22 56 a7 10 7b db 1e   P"`.....B.V..{..
    0070 - 0a ad 4a 91 a4 68 7a b0-9e 34 01 ec b8 7b b2 2f   ..J......4...{./
    0080 - e8 33 f5 a9 48 11 36 f8-69 a6 7a a6 22 52 b1 da   .3..H...i....R..
    0090 - 51 18 ed c4 d9 3d c4 cc-5b d7 ff 92 4e 91 02 9e   .....=......N...
    Start Time: 140...549
    Timeout   : 300 (sec)
    Verify return code: 19 (self signed certificate in certificate chain)

Good luck! PD: if u want more answers please check:

Submit form after calling e.preventDefault()

In my case there was a race, as I needed the ajax response to fill a hidden field and send the form after it's filled. I fixed it with putting e.preventDefault() into a condition.

var all_is_done=false;
function do_the_stuf(){
  //do stuff

CSS content property: is it possible to insert HTML instead of Text?

It is not possible prolly cuz it would be so easy to XSS. Also , current HTML sanitizers that are available don't disallow content property.

(Definitely not the greatest answer here but I just wanted to share an insight other than the "according to spec... ")

How to handle Uncaught (in promise) DOMException: The play() request was interrupted by a call to pause()

For Chrome they changed autoplay policy, so you can read about here:

var promise = document.querySelector('audio').play();

if (promise !== undefined) {
    promise.then(_ => {
        // Autoplay started!
    }).catch(error => {
        // Autoplay was prevented.
        // Show a "Play" button so that user can start playback.

Find the index of a dict within a list, by matching the dict's value

lst = [{'id':'1234','name':'Jason'}, {'id':'2345','name':'Tom'}, {'id':'3456','name':'Art'}]

tom_index = next((index for (index, d) in enumerate(lst) if d["name"] == "Tom"), None)
# 1

If you need to fetch repeatedly from name, you should index them by name (using a dictionary), this way get operations would be O(1) time. An idea:

def build_dict(seq, key):
    return dict((d[key], dict(d, index=index)) for (index, d) in enumerate(seq))

info_by_name = build_dict(lst, key="name")
tom_info = info_by_name.get("Tom")
# {'index': 1, 'id': '2345', 'name': 'Tom'}

How to get file size in Java

Did a quick google. Seems that to find the file size you do this,

long size = f.length();

The differences between the three methods you posted can be found here

getFreeSpace() and getTotalSpace() are pretty self explanatory, getUsableSpace() seems to be the space that the JVM can use, which in most cases will be the same as the amount of free space.

wamp server mysql user id and password

Just login into http://localhost/phpmyadmin/

with username:root


with blank password. And then choose users account.And then choose add user account.

How to make a JTable non-editable

create new DefaultCellEditor class :

public static class Editor_name extends DefaultCellEditor {
  public Editor_name(JCheckBox checkBox) {
  public boolean isCellEditable(EventObject anEvent) {
    return false;

and use setCellEditor :

JTable table = new JTable();
table.getColumn("columnName").setCellEditor(new Editor_name(new JCheckBox()));

Javascript Uncaught Reference error Function is not defined

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

Easiest fix is to change:

function something(...)


window.something = function(...)

Node.js Write a line into a .txt file

Inserting data into the middle of a text file is not a simple task. If possible, you should append it to the end of your file.

The easiest way to append data some text file is to use build-in fs.appendFile(filename, data[, options], callback) function from fs module:

var fs = require('fs')
fs.appendFile('log.txt', 'new data', function (err) {
  if (err) {
    // append failed
  } else {
    // done

But if you want to write data to log file several times, then it'll be best to use fs.createWriteStream(path[, options]) function instead:

var fs = require('fs')
var logger = fs.createWriteStream('log.txt', {
  flags: 'a' // 'a' means appending (old data will be preserved)

logger.write('some data') // append string to your file
logger.write('more data') // again
logger.write('and more') // again

Node will keep appending new data to your file every time you'll call .write, until your application will be closed, or until you'll manually close the stream calling .end:

logger.end() // close string

How to use git merge --squash?

git pull
git checkout -b A_NEW_BRANCH
git commit -am "squashing all commits into one"
git push --set-upstream origin A_NEW_BRANCH

Using grep to search for a string that has a dot in it

You need to escape the . as "0\.49".

A . is a regex meta-character to match any character(except newline). To match a literal period, you need to escape it.

How to import an existing project from GitHub into Android Studio

In Github click the "Clone or download" button of the project you want to import --> download the ZIP file and unzip it. In Android Studio Go to File -> New Project -> Import Project and select the newly unzipped folder -> press OK. It will build the Gradle automatically.

Good Luck with your project

MongoDB Aggregation: How to get total records count?

//const total_count = await User.find(query).countDocuments();
//const users = await User.find(query).skip(+offset).limit(+limit).sort({[sort]: order}).select('-password');
const result = await User.aggregate([
  {$match : query},
  {$sort: {[sort]:order}},
  {$project: {password: 0, avatarData: 0, tokens: 0}},
      users: [{ $skip: +offset }, { $limit: +limit}],
      totalCount: [
          $count: 'count'
return res.status(200).json({users: result[0].users, total_count: result[0].totalCount[0].count});

How to create dispatch queue in Swift 3

Since the OP question has already been answered above I just want to add some speed considerations:

It makes a lot of difference what priority class you assign to your async function in

I don't recommend running tasks with the .background thread priority especially on the iPhone X where the task seems to be allocated on the low power cores.

Here is some real data from a computationally intensive function that reads from an XML file (with buffering) and performs data interpolation:

Device name / .background / .utility / .default / .userInitiated / .userInteractive

  1. iPhone X: 18.7s / 6.3s / 1.8s / 1.8s / 1.8s
  2. iPhone 7: 4.6s / 3.1s / 3.0s / 2.8s / 2.6s
  3. iPhone 5s: 7.3s / 6.1s / 4.0s / 4.0s / 3.8s

Note that the data set is not the same for all devices. It's the biggest on the iPhone X and the smallest on the iPhone 5s.

Array vs ArrayList in performance

I agree with somebody's recently deleted post that the differences in performance are so small that, with very very few exceptions, (he got dinged for saying never) you should not make your design decision based upon that.

In your example, where the elements are Objects, the performance difference should be minimal.

If you are dealing with a large number of primitives, an array will offer significantly better performance, both in memory and time.

Rails Root directory path?

Simply by Rails.root or if you want append something we can use it like Rails.root.join('app', 'assets').to_s

Reset auto increment counter in postgres

If you created the table product with an id column, then the sequence is not simply called product, but rather product_id_seq (that is, ${table}_${column}_seq).

This is the ALTER SEQUENCE command you need:


You can see the sequences in your database using the \ds command in psql. If you do \d product and look at the default constraint for your column, the nextval(...) call will specify the sequence name too.

macro run-time error '9': subscript out of range

Why are you using a macro? Excel has Password Protection built-in. When you select File/Save As... there should be a Tools button by the Save button, click it then "General Options" where you can enter a "Password to Open" and a "Password to Modify".

How to explicitly obtain post data in Spring MVC?

Spring MVC runs on top of the Servlet API. So, you can use HttpServletRequest#getParameter() for this:

String value1 = request.getParameter("value1");
String value2 = request.getParameter("value2");

The HttpServletRequest should already be available to you inside Spring MVC as one of the method arguments of the handleRequest() method.

How to install mod_ssl for Apache httpd?

Are any other LoadModule commands referencing modules in the /usr/lib/httpd/modules folder? If so, you should be fine just adding LoadModule ssl_module /usr/lib/httpd/modules/ to your conf file.

Otherwise, you'll want to copy the file to whatever directory the other modules are being loaded from and reference it there.

Listing files in a directory matching a pattern in Java

See File#listFiles(FilenameFilter).

File dir = new File(".");
File [] files = dir.listFiles(new FilenameFilter() {
    public boolean accept(File dir, String name) {
        return name.endsWith(".xml");

for (File xmlfile : files) {

Is there a way to run Python on Android?

Cross-Compilation & Ignifuga

My blog has instructions and a patch for cross compiling Python 2.7.2 for Android.

I've also open sourced Ignifuga, my 2D Game Engine. It's Python/SDL based, and it cross compiles for Android. Even if you don't use it for games, you might get useful ideas from the code or builder utility (named Schafer, after Tim... you know who).

What's the difference between a POST and a PUT HTTP REQUEST?

Actually there's no difference other than their title. There's actually a basic difference between GET and the others. With a "GET"-Request method, you send the data in the url-address-line, which are separated first by a question-mark, and then with a & sign.

But with a "POST"-request method, you can't pass data through the url, but you have to pass the data as an object in the so called "body" of the request. On the server side, you have then to read out the body of the received content in order to get the sent data. But there's on the other side no possibility to send content in the body, when you send a "GET"-Request.

The claim, that "GET" is only for getting data and "POST" is for posting data, is absolutely wrong. Noone can prevent you from creating new content, deleting existing content, editing existing content or do whatever in the backend, based on the data, that is sent by the "GET" request or by the "POST" request. And nobody can prevent you to code the backend in a way, that with a "POST"-Request, the client asks for some data.

With a request, no matter which method you use, you call a URL and send or don't send some data to specify, which information you want to pass to the server to deal with your request, and then the client gets an answer from the server. The data can contain whatever you want to send, the backend is allowed to do whatever it wants with the data and the response can contain any information, that you want to put in there.

There are only these two BASIC METHODS. GET and POST. But it's their structure, which makes them different and not what you code in the backend. In the backend you can code whatever you want to, with the received data. But with the "POST"-request you have to send/retrieve the data in the body and not in the url-addressline, and with a "GET" request, you have to send/retrieve data in the url-addressline and not in the body. That's all.

All the other methods, like "PUT", "DELETE" and so on, they have the same structure as "POST".

The POST Method is mainly used, if you want to hide the content somewhat, because whatever you write in the url-addressline, this will be saved in the cache and a GET-Method is the same as writing a url-addressline with data. So if you want to send sensitive data, which is not always necessarily username and password, but for example some ids or hashes, which you don't want to be shown in the url-address-line, then you should use the POST method.

Also the URL-Addressline's length is limited to 1024 symbols, whereas the "POST"-Method is not restricted. So if you have a bigger amount of data, you might not be able to send it with a GET-Request, but you'll need to use the POST-Request. So this is also another plus point for the POST-request.

But dealing with the GET-request is way easier, when you don't have complicated text to send. Otherwise, and this is another plus point for the POST method, is, that with the GET-method you need to url-encode the text, in order to be able to send some symbols within the text or even spaces. But with a POST method you have no restrictions and your content doesn't need to be changed or manipulated in any way.

List changes unexpectedly after assignment. How do I clone or copy it to prevent this?

What are the options to clone or copy a list in Python?

In Python 3, a shallow copy can be made with:

a_copy = a_list.copy()

In Python 2 and 3, you can get a shallow copy with a full slice of the original:

a_copy = a_list[:]


There are two semantic ways to copy a list. A shallow copy creates a new list of the same objects, a deep copy creates a new list containing new equivalent objects.

Shallow list copy

A shallow copy only copies the list itself, which is a container of references to the objects in the list. If the objects contained themselves are mutable and one is changed, the change will be reflected in both lists.

There are different ways to do this in Python 2 and 3. The Python 2 ways will also work in Python 3.

Python 2

In Python 2, the idiomatic way of making a shallow copy of a list is with a complete slice of the original:

a_copy = a_list[:]

You can also accomplish the same thing by passing the list through the list constructor,

a_copy = list(a_list)

but using the constructor is less efficient:

>>> timeit
>>> l = range(20)
>>> min(timeit.repeat(lambda: l[:]))
>>> min(timeit.repeat(lambda: list(l)))

Python 3

In Python 3, lists get the list.copy method:

a_copy = a_list.copy()

In Python 3.5:

>>> import timeit
>>> l = list(range(20))
>>> min(timeit.repeat(lambda: l[:]))
>>> min(timeit.repeat(lambda: list(l)))
>>> min(timeit.repeat(lambda: l.copy()))

Making another pointer does not make a copy

Using new_list = my_list then modifies new_list every time my_list changes. Why is this?

my_list is just a name that points to the actual list in memory. When you say new_list = my_list you're not making a copy, you're just adding another name that points at that original list in memory. We can have similar issues when we make copies of lists.

>>> l = [[], [], []]
>>> l_copy = l[:]
>>> l_copy
[[], [], []]
>>> l_copy[0].append('foo')
>>> l_copy
[['foo'], [], []]
>>> l
[['foo'], [], []]

The list is just an array of pointers to the contents, so a shallow copy just copies the pointers, and so you have two different lists, but they have the same contents. To make copies of the contents, you need a deep copy.

Deep copies

To make a deep copy of a list, in Python 2 or 3, use deepcopy in the copy module:

import copy
a_deep_copy = copy.deepcopy(a_list)

To demonstrate how this allows us to make new sub-lists:

>>> import copy
>>> l
[['foo'], [], []]
>>> l_deep_copy = copy.deepcopy(l)
>>> l_deep_copy[0].pop()
>>> l_deep_copy
[[], [], []]
>>> l
[['foo'], [], []]

And so we see that the deep copied list is an entirely different list from the original. You could roll your own function - but don't. You're likely to create bugs you otherwise wouldn't have by using the standard library's deepcopy function.

Don't use eval

You may see this used as a way to deepcopy, but don't do it:

problematic_deep_copy = eval(repr(a_list))
  1. It's dangerous, particularly if you're evaluating something from a source you don't trust.
  2. It's not reliable, if a subelement you're copying doesn't have a representation that can be eval'd to reproduce an equivalent element.
  3. It's also less performant.

In 64 bit Python 2.7:

>>> import timeit
>>> import copy
>>> l = range(10)
>>> min(timeit.repeat(lambda: copy.deepcopy(l)))
>>> min(timeit.repeat(lambda: eval(repr(l))))

on 64 bit Python 3.5:

>>> import timeit
>>> import copy
>>> l = list(range(10))
>>> min(timeit.repeat(lambda: copy.deepcopy(l)))
>>> min(timeit.repeat(lambda: eval(repr(l))))

PHPExcel - set cell type before writing a value in it

For Numbers with leading zeroes and comma separated:

You can put 'A' to affect the entire column'.


Then you can write to the cell as you normally would.

slideToggle JQuery right to left

You can do this using additional effects as a part of jQuery-ui

$('.show_hide').click(function () {

Test Link

How to set aliases in the Git Bash for Windows?

  • Go to: C:\Users\ [youruserdirectory] \bash_profile

  • In your bash_profile file type - alias desk='cd " [DIRECTORY LOCATION] "'

  • Refresh your User directory where the bash_profile file exists then reopen your CMD or Git Bash window

Type in desk to see if you get to the Desktop location or the location you want in the "DIRECTORY LOCATION" area above

Note: [ desk ] can be what ever name that you choose and should get you to the location you want to get to when typed in the CMD window.

How to return rows from left table not found in right table?

I also like to use NOT EXISTS. When it comes to performance if index correctly it should perform the same as a LEFT JOIN or better. Plus its easier to read.

SELECT Column1
FROM TableA a
                   FROM Tableb b
                   WHERE a.Column1 = b.Column1

What is a "callback" in C and how are they implemented?

A simple call back program. Hope it answers your question.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include "../../common_typedef.h"

typedef void (*call_back) (S32, S32);

void test_call_back(S32 a, S32 b)
    printf("In call back function, a:%d \t b:%d \n", a, b);

void call_callback_func(call_back back)
    S32 a = 5;
    S32 b = 7;

    back(a, b);

S32 main(S32 argc, S8 *argv[])
    S32 ret = SUCCESS;

    call_back back;

    back = test_call_back;


    return ret;

Printing Exception Message in java

The output looks correct to me:

Invalid JavaScript code: missing } after property list (<Unknown source>) in <Unknown source>; at line number 1

I think Invalid Javascript code: .. is the start of the exception message.

Normally the stacktrace isn't returned with the message:

try {
    throw new RuntimeException("hu?\ntrace-line1\ntrace-line2");
} catch (Exception e) {
    System.out.println(e.getMessage()); // prints "hu?"

So maybe the code you are calling catches an exception and rethrows a ScriptException. In this case maybe e.getCause().getMessage() can help you.

Difference between git stash pop and git stash apply

Got this helpful link that states the difference, as John Zwinck has stated and a drawback of git stash pop.

For instance, say your stashed changes conflict with other changes that you’ve made since you first created the stash. Both pop and apply will helpfully trigger merge conflict resolution mode, allowing you to nicely resolve such conflicts… and neither will get rid of the stash, even though perhaps you’re expecting pop too. Since a lot of people expect stashes to just be a simple stack, this often leads to them popping the same stash accidentally later because they thought it was gone.


python NameError: global name '__file__' is not defined

If you're exec'ing a file via command line, you can use this hack

import traceback

def get_this_filename():
        raise NotImplementedError("No error")
    except Exception as e:
        exc_type, exc_value, exc_traceback = sys.exc_info()
        filename = traceback.extract_tb(exc_traceback)[-1].filename
    return filename

This worked for me in the UnrealEnginePython console, calling py.exec

TypeScript: Interfaces vs Types

Interfaces vs types

Interfaces and types are used to describe the types of objects and primitives. Both interfaces and types can often be used interchangeably and often provide similar functionality. Usually it is the choice of the programmer to pick their own preference.

However, interfaces can only describe objects and classes that create these objects. Therefore types must be used in order to describe primitives like strings and numbers.

Here is an example of 2 differences between interfaces and types:

// 1. Declaration merging (interface only)

// This is an extern dependency which we import an object of
interface externDependency { x: number, y: number; }
// When we import it, we might want to extend the interface, e.g. z:number
// We can use declaration merging to define the interface multiple times
// The declarations will be merged and become a single interface
interface externDependency { z: number; }
const dependency: externDependency = {x:1, y:2, z:3}

// 2. union types with primitives (type only)

type foo = {x:number}
type bar = { y: number }
type baz = string | boolean;

type foobarbaz = foo | bar | baz; // either foo, bar, or baz type

// instances of type foobarbaz can be objects (foo, bar) or primitives (baz)
const instance1: foobarbaz = {y:1} 
const instance2: foobarbaz = {x:1} 
const instance3: foobarbaz = true 

How to set environment variable for everyone under my linux system?

If your LinuxOS has this file:


You can use it to permanently set environmental variables for all users.

Extracted from:

What is the technology behind wechat, whatsapp and other messenger apps?

The WhatsApp Architecture Facebook Bought For $19 Billion explains the architecture involved in design of whatsapp.

Here is the general explanation from the link

  • WhatsApp server is almost completely implemented in Erlang.

  • Server systems that do the backend message routing are done in Erlang.

  • Great achievement is that the number of active users is managed with a really small server footprint. Team consensus is that it is largely because of Erlang.

  • Interesting to note Facebook Chat was written in Erlang in 2009, but they went away from it because it was hard to find qualified programmers.

  • WhatsApp server has started from ejabberd

  • Ejabberd is a famous open source Jabber server written in Erlang.

  • Originally chosen because its open, had great reviews by developers, ease of start and the promise of Erlang’s long term suitability for large communication system.

  • The next few years were spent re-writing and modifying quite a few parts of ejabberd, including switching from XMPP to internally developed protocol, restructuring the code base and redesigning some core components, and making lots of important modifications to Erlang VM to optimize server performance.

  • To handle 50 billion messages a day the focus is on making a reliable system that works. Monetization is something to look at later, it’s far far down the road.

  • A primary gauge of system health is message queue length. The message queue length of all the processes on a node is constantly monitored and an alert is sent out if they accumulate backlog beyond a preset threshold. If one or more processes falls behind that is alerted on, which gives a pointer to the next bottleneck to attack.

  • Multimedia messages are sent by uploading the image, audio or video to be sent to an HTTP server and then sending a link to the content along with its Base64 encoded thumbnail (if applicable).

  • Some code is usually pushed every day. Often, it’s multiple times a day, though in general peak traffic times are avoided. Erlang helps being aggressive in getting fixes and features into production. Hot-loading means updates can be pushed without restarts or traffic shifting. Mistakes can usually be undone very quickly, again by hot-loading. Systems tend to be much more loosely-coupled which makes it very easy to roll changes out incrementally.

  • What protocol is used in Whatsapp app? SSL socket to the WhatsApp server pools. All messages are queued on the server until the client reconnects to retrieve the messages. The successful retrieval of a message is sent back to the whatsapp server which forwards this status back to the original sender (which will see that as a "checkmark" icon next to the message). Messages are wiped from the server memory as soon as the client has accepted the message

  • How does the registration process work internally in Whatsapp? WhatsApp used to create a username/password based on the phone IMEI number. This was changed recently. WhatsApp now uses a general request from the app to send a unique 5 digit PIN. WhatsApp will then send a SMS to the indicated phone number (this means the WhatsApp client no longer needs to run on the same phone). Based on the pin number the app then request a unique key from WhatsApp. This key is used as "password" for all future calls. (this "permanent" key is stored on the device). This also means that registering a new device will invalidate the key on the old device.

Impersonate tag in Web.Config

You had the identity node as a child of authentication node. That was the issue. As in the example above, authentication and identity nodes must be children of the system.web node

Using a cursor with dynamic SQL in a stored procedure

First off, avoid using a cursor if at all possible. Here are some resources for rooting it out when it seems you can't do without:

There Must Be 15 Ways To Lose Your Cursors... part 1, Introduction

Row-By-Row Processing Without Cursor

That said, though, you may be stuck with one after all--I don't know enough from your question to be sure that either of those apply. If that's the case, you've got a different problem--the select statement for your cursor must be an actual SELECT statement, not an EXECUTE statement. You're stuck.

But see the answer from cmsjr (which came in while I was writing) about using a temp table. I'd avoid global cursors even more than "plain" ones....

How to convert all tables from MyISAM into InnoDB?

Yet another option... Here's how to do it in ansible. It assumes that the name of your database is in dbname and that you have already configured access.

- name: Get list of DB tables that need converting to InnoDB
  command: >
    mysql --batch --skip-column-names --execute="SELECT TABLE_NAME
    FROM information_schema.TABLES
    WHERE TABLE_SCHEMA = '{{ dbname }}' AND ENGINE = 'MyISAM';"
  register: converttables
  check_mode: no
  changed_when: False

- name: Convert any unconverted tables
  command: >
    mysql --batch --skip-column-names --execute="ALTER TABLE `{{ dbname }}`.`{{ item }}` ENGINE = InnoDB;"
  with_items: "{{ converttables.stdout_lines }}"

How to load images dynamically (or lazily) when users scrolls them into view

I came up with my own basic method which seems to work fine (so far). There's probably a dozen things some of the popular scripts address that I haven't thought of.

Note - This solution is fast and easy to implement but of course not great for performance. Definitely look into the new Intersection Observer as mentioned by Apoorv and explained by if performance is an issue.

The JQuery

$(window).scroll(function() {
    $.each($('img'), function() {
        if ( $(this).attr('data-src') && $(this).offset().top < ($(window).scrollTop() + $(window).height() + 100) ) {
            var source = $(this).data('src');
            $(this).attr('src', source);

Sample html code

    <img src="" data-src="pathtoyour/image1.jpg">
    <img src="" data-src="pathtoyour/image2.jpg">
    <img src="" data-src="pathtoyour/image3.jpg">


When the page is scrolled each image on the page is checked..

$(this).attr('data-src') - if the image has the attribute data-src

and how far those images are from the bottom of the window..

$(this).offset().top < ($(window).scrollTop() + $(window).height() + 100)

adjust the + 100 to whatever you like (- 100 for example)

var source = $(this).data('src'); - gets the value of data-src= aka the image url

$(this).attr('src', source); - puts that value into the src=

$(this).removeAttr('data-src'); - removes the data-src attribute (so your browser doesn't waste resources messing with the images that have already loaded)

Adding To Existing Code

To convert your html, in an editor just search and replace src=" with src="" data-src="

How to convert enum value to int?

Maybe it's better to use a String representation than an integer, because the String is still valid if values are added to the enum. You can use the enum's name() method to convert the enum value to a String an the enum's valueOf() method to create an enum representation from the String again. The following example shows how to convert the enum value to String and back (ValueType is an enum):

ValueType expected = ValueType.FLOAT;
String value =;

System.out.println("Name value: " + value);

ValueType actual = ValueType.valueOf(value);

if(expected.equals(actual)) System.out.println("Values are equal");

In Java, what purpose do the keywords `final`, `finally` and `finalize` fulfil?

final – constant declaration.

finally – The finally block always executes when the try block exits, except System.exit(0) call. This ensures that the finally block is executed even if an unexpected exception occurs. But finally is useful for more than just exception handling — it allows the programmer to avoid having cleanup code accidentally bypassed by a return, continue, or break. Putting cleanup code in a finally block is always a good practice, even when no exceptions are anticipated.

finalize() – method helps in garbage collection. A method that is invoked before an object is discarded by the garbage collector, allowing it to clean up its state. Should not be used to release non-memory resources like file handles, sockets, database connections etc because Java has only a finite number of these resources and you do not know when the garbage collection is going to kick in to release these non-memory resources through the finalize() method.

Did you try searching on google, and need clarification for an explanation?

Oracle: SQL select date with timestamp

You can specify the whole day by doing a range, like so:

WHERE bk_date >= TO_DATE('2012-03-18', 'YYYY-MM-DD')
AND bk_date <  TO_DATE('2012-03-19', 'YYYY-MM-DD')

More simply you can use TRUNC:

WHERE TRUNC(bk_date) = TO_DATE('2012-03-18', 'YYYY-MM-DD')

TRUNC without parameter removes hours, minutes and seconds from a DATE.

PHPMailer: SMTP Error: Could not connect to SMTP host

In my case it was a lack of SSL support in PHP which gave this error.

So I enabled extension=php_openssl.dll

$mail->SMTPDebug = 1; also hinted towards this solution.

Update 2017

$mail->SMTPDebug = 2;, see:

How can we redirect a Java program console output to multiple files?

Go to run as and choose Run Configurations -> Common and in the Standard Input and Output you can choose a File also.

Convert string to float?

Use Float.valueOf(String) to do the conversion.

The difference between valueOf() and parseFloat() is only the return. Use the former if you want a Float (object) and the latter if you want the float number.

How to encode text to base64 in python

Use the below code:

import base64

#Taking input through the terminal.
welcomeInput= raw_input("Enter 1 to convert String to Base64, 2 to convert Base64 to String: ") 

if(int(welcomeInput)==1 or int(welcomeInput)==2):
    #Code to Convert String to Base 64.
    if int(welcomeInput)==1:
        inputString= raw_input("Enter the String to be converted to Base64:") 
        base64Value = base64.b64encode(inputString.encode())
        print "Base64 Value = " + base64Value
    #Code to Convert Base 64 to String.
    elif int(welcomeInput)==2:
        inputString= raw_input("Enter the Base64 value to be converted to String:") 
        stringValue = base64.b64decode(inputString).decode('utf-8')
        print "Base64 Value = " + stringValue

    print "Please enter a valid value."

Escaping double quotes in JavaScript onClick event handler

I think that the best approach is to assign the onclick handler unobtrusively.

Something like this:

window.onload = function(){
    var myLink = document.getElementsById('myLinkId');
    myLink.onclick = function(){ 
        parse('#', false, '<a href="xyz');
        return false;


<a href="#" id="myLink">Test</a>

Duplicate and rename Xcode project & associated folders

This answer is the culmination of various other StackOverflow posts and tutorials around the internet brought into one place for my future reference, and to help anyone else who may be facing the same issue. All credit is given for other answers at the end.

Duplicating an Xcode Project

  • In the Finder, duplicate the project folder to the desired location of your new project. Do not rename the .xcodeproj file name or any associated folders at this stage.

  • In Xcode, rename the project. Select your project from the navigator pane (left pane). In the Utilities pane (right pane) rename your project, Accept the changes Xcode proposes.

  • In Xcode, rename the schemes in "Manage Schemes", also rename any targets you may have.

  • If you're not using the default Bundle Identifier which contains the current PRODUCT_NAME at the end (so will update automatically), then change your Bundle Identifier to the new one you will be using for your duplicated project.

Renaming the source folder

So after following the above steps you should have a duplicated and renamed Xcode project that should build and compile successfully, however your source code folder will still be named as it was in the original project. This doesn't cause any compiler issues, but it's not the clearest file structure for people to navigate in SCM, etc. To rename this folder without breaking all your file links, follow these steps:

  • In the Finder, rename the source folder. This will break your project, because Xcode won't automatically detect the changes. All of your xcode file listings will lose their links with the actual files, so will all turn red.

  • In Xcode, click on the virtual folder which you renamed (This will likely be right at the top, just under your actual .xcodeproject) Rename this to match the name in the Finder, this won't fix anything and strictly isn't a required step but it's nice to have the file names matching.

  • In Xcode, Select the folder you just renamed in the navigation pane. Then in the Utilities pane (far right) click the icon that looks like dark grey folder, just underneath the 'Location' drop down menu. From here, navigate to your renamed folder in the finder and click 'Choose'. This will automagically re-associate all your files, and they should no longer appear red within the Xcode navigation pane.

Icon to click

  • In your project / targets build settings, search for the old folder name and manually rename any occurrences you find. Normally there is one for the prefix.pch and one for the info.plist, but there may be more.

  • If you are using any third party libraries (Testflight/Hockeyapp/etc) you will also need to search for 'Library Search Paths' and rename any occurrences of the old file name here too.

  • Repeat this process for any unit test source code folders your project may contain, the process is identical.

This should allow you to duplicate & rename an xcode project and all associated files without having to manually edit any xcode files, and risk messing things up.


Many thanks is given to Nick Lockwood, and Pauly Glott for providing the separate answers to this problem.

Create intermediate folders if one doesn't exist

A nice Java 7+ answer from Benoit Blanchon can be found here:

With Java 7, you can use Files.createDirectories().

For instance:


Leave menu bar fixed on top when scrolled

Or do this in more dynamic way

$(window).bind('scroll', function () {
    var menu = $('.menu');
    if ($(window).scrollTop() > menu.offset().top) {
    } else {

In CSS add class

.fixed {
    position: fixed;
    top: 0;

SQL to generate a list of numbers from 1 to 100

Another interesting solution in ORACLE PL/SQL:


How can I draw circle through XML Drawable - Android?

no need for the padding or the corners.

here's a sample:

<shape xmlns:android="" android:shape="oval" >
    <gradient android:startColor="#FFFF0000" android:endColor="#80FF00FF"

based on :

Datagridview: How to set a cell in editing mode?

I know this question is pretty old, but figured I'd share some demo code this question helped me with.

  • Create a Form with a Button and a DataGridView
  • Register a Click event for button1
  • Register a CellClick event for DataGridView1
  • Set DataGridView1's property EditMode to EditProgrammatically
  • Paste the following code into Form1:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
    public partial class Form1 : Form
        DataTable m_dataTable;
        DataTable table { get { return m_dataTable; } set { m_dataTable = value; } }

        private const string m_nameCol = "Name";
        private const string m_choiceCol = "Choice";

        public Form1()

        class Options
            public int m_Index { get; set; }
            public string m_Text { get; set; }

        private void button1_Click(object sender, EventArgs e)
            table = new DataTable();
            table.Rows.Add(new object[] { "Foo" });
            table.Rows.Add(new object[] { "Bob" });
            table.Rows.Add(new object[] { "Timn" });
            table.Rows.Add(new object[] { "Fred" });

            dataGridView1.DataSource = table;

            if (!dataGridView1.Columns.Contains(m_choiceCol))
                DataGridViewTextBoxColumn txtCol = new DataGridViewTextBoxColumn();
                txtCol.Name = m_choiceCol;

            List<Options> oList = new List<Options>();
            oList.Add(new Options() { m_Index = 0, m_Text = "None" });
            for (int i = 1; i < 10; i++)
                oList.Add(new Options() { m_Index = i, m_Text = "Op" + i });

            for (int i = 0; i < dataGridView1.Rows.Count - 1; i += 2)
                DataGridViewComboBoxCell c = new DataGridViewComboBoxCell();

                //Setup A
                c.DataSource = oList;
                c.Value = oList[0].m_Text;
                c.ValueMember = "m_Text";
                c.DisplayMember = "m_Text";
                c.ValueType = typeof(string);

                ////Setup B
                //c.DataSource = oList;
                //c.Value = 0;
                //c.ValueMember = "m_Index";
                //c.DisplayMember = "m_Text";
                //c.ValueType = typeof(int);

                //Result is the same A or B
                dataGridView1[m_choiceCol, i] = c;

        private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
            if (e.ColumnIndex >= 0 && e.RowIndex >= 0)
                if (dataGridView1.CurrentCell.ColumnIndex == dataGridView1.Columns.IndexOf(dataGridView1.Columns[m_choiceCol]))
                    DataGridViewCell cell = dataGridView1[m_choiceCol, e.RowIndex];
                    dataGridView1.CurrentCell = cell;

Note that the column index numbers can change from multiple button presses of button one, so I always refer to the columns by name not index value. I needed to incorporate David Hall's answer into my demo that already had ComboBoxes so his answer worked really well.

How to import Google Web Font in CSS file?

Jus go through the link

To import it to stylesheet use

@import url('');

Count of "Defined" Array Elements

Unfortunately, No. You will you have to go through a loop and count them.


var arrLength = arr.filter(Number);

MSSQL Select statement with incremental integer column... not from a table

You can start with a custom number and increment from there, for example you want to add a cheque number for each payment you can do:

select @StartChequeNumber = 3446;
((ROW_NUMBER() OVER(ORDER BY AnyColumn)) + @StartChequeNumber ) AS 'ChequeNumber'
,* FROM YourTable

will give the correct cheque number for each row.

HTML img align="middle" doesn't align an image

How about this? I frequently use the CSS Flexible Box Layout to center something.

<div style="display: flex; justify-content: center;">_x000D_
  <img src="" style="width: 40px; height: 40px;" />_x000D_

What is the difference between private and protected members of C++ classes?

Private members are only accessible within the class defining them.

Protected members are accessible in the class that defines them and in classes that inherit from that class.

Edit: Both are also accessible by friends of their class, and in the case of protected members, by friends of their derived classes.

Edit 2: Use whatever makes sense in the context of your problem. You should try to make members private whenever you can to reduce coupling and protect the implementation of the base class, but if that's not possible then use protected members. Check C++ FAQ for a better understanding of the issue. This question about protected variables might also help.

Maximum length for MySQL type text

TINYTEXT 256 bytes
TEXT 65,535 bytes ~64kb
MEDIUMTEXT 16,777,215 bytes ~16MB
LONGTEXT 4,294,967,295 bytes ~4GB

TINYTEXT is a string data type that can store up to to 255 characters.

TEXT is a string data type that can store up to 65,535 characters. TEXT is commonly used for brief articles.

LONGTEXT is a string data type with a maximum length of 4,294,967,295 characters. Use LONGTEXT if you need to store large text, such as a chapter of a novel.

Does not contain a static 'main' method suitable for an entry point

For me, the error was actually produced by "Feature 'async main' is not available in C# 7.0. Please use language version 7.1 or greater". This issue was resulting in the "Does not contain a static 'main' method suitable for an entry point" message in the Error List, but the Output window showed the "not available" error. To correct this, I changed the language version from 'C# latest minor version (default)' to 'C# latest minor version (latest)' under Advanced Build Settings.

How to install Boost on Ubuntu

Actually you don't need "install" or "compile" anything before using Boost in your project. You can just download and extract the Boost library to any location on your machine, which is usually like /usr/local/.

When you compile your code, you can just indicate the compiler where to find the libraries by -I. For example, g++ -I /usr/local/boost_1_59_0 xxx.hpp.

How to properly apply a lambda function into a pandas data frame column

You need mask:

sample['PR'] = sample['PR'].mask(sample['PR'] < 90, np.nan)

Another solution with loc and boolean indexing:

sample.loc[sample['PR'] < 90, 'PR'] = np.nan


import pandas as pd
import numpy as np

sample = pd.DataFrame({'PR':[10,100,40] })
print (sample)
0   10
1  100
2   40

sample['PR'] = sample['PR'].mask(sample['PR'] < 90, np.nan)
print (sample)
0    NaN
1  100.0
2    NaN
sample.loc[sample['PR'] < 90, 'PR'] = np.nan
print (sample)
0    NaN
1  100.0
2    NaN


Solution with apply:

sample['PR'] = sample['PR'].apply(lambda x: np.nan if x < 90 else x)

Timings len(df)=300k:

sample = pd.concat([sample]*100000).reset_index(drop=True)

In [853]: %timeit sample['PR'].apply(lambda x: np.nan if x < 90 else x)
10 loops, best of 3: 102 ms per loop

In [854]: %timeit sample['PR'].mask(sample['PR'] < 90, np.nan)
The slowest run took 4.28 times longer than the fastest. This could mean that an intermediate result is being cached.
100 loops, best of 3: 3.71 ms per loop

cin and getline skipping input

Here, the '\n' left by cin, is creating issues.

do {
    cin >> choice;               #This cin is leaving a trailing \n

    switch (choice) {
        case '1':

This \n is being consumed by next getline in createNewCustomer(). You should use getline instead -

do {
    getline(cin, choice)               

    switch (choice) {
        case '1':

I think this would resolve the issue.

Setting environment variables for accessing in PHP when using Apache

Unbelievable, but on httpd 2.2 on centos 6.4 this works.

Export env vars in /etc/sysconfig/httpd

export mydocroot=/var/www/html

Then simply do this...

<VirtualHost *:80>
  DocumentRoot ${mydocroot}

Then finally....

service httpd restart;

Is there a color code for transparent in HTML?

{background-color: transparent;}

Displaying standard DataTables in MVC

Here is the answer in Razor syntax

 <table border="1" cellpadding="5">
          @foreach (System.Data.DataColumn col in Model.Columns)
    @foreach(System.Data.DataRow row in Model.Rows)
          @foreach (var cell in row.ItemArray)

How do I convert dmesg timestamp to custom date format?

In recent versions of dmesg, you can just call dmesg -T.

chrome undo the action of "prevent this page from creating additional dialogs"

2 more solutions I had luck with when neither tab close + reopening the page in another tab nor closing all tabs in Chrome (and the browser) then restarting it didn't work:

1) I fixed it on my machine by closing the tab, force-closing Chrome, & restarting the browser without restoring tabs (Note: on a computer running CentOS Linux).

2) My boss (also on CentOS) had the same issue (alerts are a big part of my company's Javascript debugging process for numerous reasons e.g. legacy), but my 1st method didn't work for him. However, I managed to fix it for him with the following process:

  • a) Make an empty text file called, and paste in the following bash script:

    #! /bin/bash
    cd ~/.config/google-chrome/Default     //adjust for your Chrome install location
    rm Preferences
    rm 'Current Session'
    rm 'Current Tabs'
    rm 'Last Session'
    rm 'Last Tabs'
  • b) close Chrome, then open Terminal and run the script (bash

It worked for him. Downside is that you lose all tabs from your current & previous session, but it's worth it if this matters to you.

How to represent empty char in Java Character class

this is how I do it.

char[] myEmptyCharArray = "".toCharArray();

Why is the Visual Studio 2015/2017/2019 Test Runner not discovering my xUnit v2 tests

It's happened to me a couple of times - when I Clean the project and Build it again it tends to be fine.

How to allow only integers in a textbox?

You can use client-side validation:

<asp:textbox onkeydown="return (!(event.keyCode>=65) && event.keyCode!=32);" />

ggplot combining two plots from different data.frames

As Baptiste said, you need to specify the data argument at the geom level. Either

#df1 is the default dataset for all geoms
(plot1 <- ggplot(df1, aes(v, p)) + 
    geom_point() +
    geom_step(data = df2)


#No default; data explicitly specified for each geom
(plot2 <- ggplot(NULL, aes(v, p)) + 
      geom_point(data = df1) +
      geom_step(data = df2)

How to get a product's image in Magento?

// Let's load the category Model and grab the product collection of that category

$product_collection = Mage::getModel('catalog/category')->load($categoryId)->getProductCollection();

// Now let's loop through the product collection and print the ID of every product 
foreach($product_collection as $product) {
  // Get the product ID

$product_id = $product->getId();

  // Load the full product model based on the product ID

$full_product = Mage::getModel('catalog/product')->load($product_id);

  // Now that we loaded the full product model, let's access all of it's data

  // Let's get the Product Name

  $product_name = $full_product->getName();

  // Let's get the Product URL path

  $product_url = $full_product->getProductUrl();

  // Let's get the Product Image URL

  $product_image_url = $full_product->getImageUrl();

  // Let's print the product information we gathered and continue onto the next one

 echo $product_name;

  echo $product_image_url;


The equivalent of wrap_content and match_parent in flutter?

A simple workaround:

If a container has only one top level child, then you can specify alignment property for the child and give it any available value. it'll fill all the space in the container.

    color: Colors.yellow,
    alignment:Alignment.[any_available_option] // make the yellow child match the parent size

Another way:

    color: Colors.yellow,
    constraints:  BoxConstraints.expand(height: 100.0), // height will be 100 dip and width will be match parent

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

MySQL says:

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

When do I use it ?

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

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

How can I trigger a JavaScript event click


function triggerEvent(el, type){
    var e = document.createEvent('HTMLEvents');
    e.initEvent(type, false, true);

Usage example:

var el = document.querySelector('input[type="text"]');
triggerEvent(el, 'mousedown');


How to draw vertical lines on a given plot in matplotlib

In addition to the plt.axvline and plt.plot((x1, x2), (y1, y2)) OR plt.plot([x1, x2], [y1, y2]) as provided in the answers above, one can also use

plt.vlines(x_pos, ymin=y1, ymax=y2)

to plot a vertical line at x_pos spanning from y1 to y2 where the values y1 and y2 are in absolute data coordinates.

Remove border radius from Select tag in bootstrap 3

In addition to border-radius: 0, add -webkit-appearance: none;.

How to disable an Android button?

In my case,


is working fine and it is enabling and disabling the button as it should. But once the button state becomes disabled, it never goes back to the enabled state again, although it's clickable. I tried invalidating and refreshing the drawable state, but no luck.


If you or anyone having a similar issue, what works for me is setting the background drawable again. Works on any API Level.


Android: How to rotate a bitmap on a center point

I came back to this problem now that we are finalizing the game and I just thought to post what worked for me.

This is the method for rotating the Matrix:

this.matrix.setTranslate(this.floatXpos, this.floatYpos);
this.matrix.postRotate((float)this.direction, this.getCenterX(), this.getCenterY()); 

(this.getCenterX() is basically the bitmaps X position + the bitmaps width / 2)

And the method for Drawing the bitmap (called via a RenderManager Class):

canvas.drawBitmap(this.bitmap, this.matrix, null);

So it is prettey straight forward but I find it abit strange that I couldn't get it to work by setRotate followed by postTranslate. Maybe some knows why this doesn't work? Now all the bitmaps rotate properly but it is not without some minor decrease in bitmap quality :/

Anyways, thanks for your help!

How to get option text value using AngularJS?

The best way is to use the ng-options directive on the select element.


function Ctrl($scope) {
  // sort options
  $scope.products = [{
    value: 'prod_1',
    label: 'Product 1'
  }, {
    value: 'prod_2',
    label: 'Product 2'


<select ng-model="selected_product" 
        ng-options="product as product.label for product in products">           

This will bind the selected product object to the ng-model property - selected_product. After that you can use this:

<p>Ordered by: {{selected_product.label}}</p>