Programs & Examples On #Process elevation

Elevating process privilege programmatically?

[PrincipalPermission(SecurityAction.Demand, Role = @"BUILTIN\Administrators")]

This will do it without UAC - no need to start a new process. If the running user is member of Admin group as for my case.

How to detect if a browser is Chrome using jQuery?

var is_chrome = /chrome/.test( navigator.userAgent.toLowerCase() );

How do I change Android Studio editor's background color?

How do I change Android Studio editor's background color?

Changing Editor's Background

Open Preference > Editor (In IDE Settings Section) > Colors & Fonts > Darcula or Any item available there

IDE will display a dialog like this, Press 'No'

Darcula color scheme has been set for editors. Would you like to set Darcula as default Look and Feel?

Changing IDE's Theme

Open Preference > Appearance (In IDE Settings Section) > Theme > Darcula or Any item available there

Press OK. Android Studio will ask you to restart the IDE.

How can I shuffle an array?

You could use the Fisher-Yates Shuffle (code adapted from this site):

function shuffle(array) {
    let counter = array.length;

    // While there are elements in the array
    while (counter > 0) {
        // Pick a random index
        let index = Math.floor(Math.random() * counter);

        // Decrease counter by 1

        // And swap the last element with it
        let temp = array[counter];
        array[counter] = array[index];
        array[index] = temp;

    return array;

How to get JavaScript caller function line number? How to get JavaScript caller source URL?

This is often achieved by throwing an error from the current context; then analyzing error object for properties like lineNumber and fileName (which some browsers have)

function getErrorObject(){
  try { throw Error('') } catch(err) { return err; }

var err = getErrorObject();

err.lineNumber; // or `err.line` in WebKit

Don't forget that callee.caller property is deprecated (and was never really in ECMA 3rd ed. in the first place).

Also remember that function decompilation is specified to be implementation dependent and so might yield quite unexpected results. I wrote about it here and here.

Can't find out where does a node.js app running and can't kill it

You can kill all node processes using pkill node

or you can do a ps T to see all processes on this terminal
then you can kill a specific process ID doing a kill [processID] example: kill 24491

Additionally, you can do a ps -help to see all the available options

No Multiline Lambda in Python: Why not?

Let me present to you a glorious but terrifying hack:

import types

def _obj():
  return lambda: None

def LET(bindings, body, env=None):
  '''Introduce local bindings.
  ex: LET(('a', 1,
           'b', 2),
          lambda o: [o.a, o.b])
  gives: [1, 2]

  Bindings down the chain can depend on
  the ones above them through a lambda.
  ex: LET(('a', 1,
           'b', lambda o: o.a + 1),
          lambda o: o.b)
  gives: 2
  if len(bindings) == 0:
    return body(env)

  env = env or _obj()
  k, v = bindings[:2]
  if isinstance(v, types.FunctionType):
    v = v(env)

  setattr(env, k, v)
  return LET(bindings[2:], body, env)

You can now use this LET form as such:

map(lambda x: LET(('y', x + 1,
                   'z', x - 1),
                  lambda o: o.y * o.z),
    [1, 2, 3])

which gives: [0, 3, 8]

how to get the value of a textarea in jquery?

in javascript :


Check if all elements in a list are identical

If you're interested in something a little more readable (but of course not as efficient,) you could try:

def compare_lists(list1, list2):
    if len(list1) != len(list2): # Weed out unequal length lists.
        return False
    for item in list1:
        if item not in list2:
            return False
    return True

a_list_1 = ['apple', 'orange', 'grape', 'pear']
a_list_2 = ['pear', 'orange', 'grape', 'apple']

b_list_1 = ['apple', 'orange', 'grape', 'pear']
b_list_2 = ['apple', 'orange', 'banana', 'pear']

c_list_1 = ['apple', 'orange', 'grape']
c_list_2 = ['grape', 'orange']

print compare_lists(a_list_1, a_list_2) # Returns True
print compare_lists(b_list_1, b_list_2) # Returns False
print compare_lists(c_list_1, c_list_2) # Returns False

How to comment multiple lines in Visual Studio Code?

If you are using VSCode in a linux environment, then you can comment multiple lines by either:

Selecting a block of code => then, press Ctrl + Shift + A (Block commenting)

Or, selecting a block of code => then, press Ctrl + / (Single-line commenting applied to all selected lines)

Hope this helps.

Input type number "only numeric value" validation

Sometimes it is just easier to try something simple like this.

validateNumber(control: FormControl): { [s: string]: boolean } {

  //revised to reflect null as an acceptable value 
  if (control.value === null) return null;

  // check to see if the control value is no a number
  if (isNaN(control.value)) {
    return { 'NaN': true };

  return null; 

Hope this helps.

updated as per comment, You need to to call the validator like this

number: new FormControl('',[this.validateNumber.bind(this)])

The bind(this) is necessary if you are putting the validator in the component which is how I do it.

Can not find the tag library descriptor for ""

Well, I have read this post and seems it is not good enough to fix this issue.

Spring based application on the tomcat 8 will not work.

Here is the solution

Step 1 ? Add the following dependency in your pom.xml

<!-- JSTL Support -->


Step 2 ? Add All following two statement in your JSP page, ensure that you are using isELIgnored="false" attribute in <%@ page %> tag

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" isELIgnored="false" pageEncoding="ISO-8859-1"%>
<%@ taglib prefix="c" uri=""%>

Step 3 ? Remove all the other configuration that you have done till now in web.xml or anywhere else :)

Step 4 ? Clean the Tomcat and restart Tomcat.

Side Note ? Actually, JSTL will work with only 3.x Servlet specifications on Tomcat 8.


Cannot read configuration file due to insufficient permissions

I had this error message that turned out to be due to my physical folder being located on a network drive as opposed to the local drive. It seems the permissions on such drives by default can be different. For example, while the local drive location gave permission to the users of the local computer, the network location did not.

Further, the accepted answer does not work for such a case. The local users or IIS users were not an available to assign permissions to. The solution was to move the physical folder to the local drive.

How to make flutter app responsive according to different screen size?

An Another approach :) easier for flutter web

class SampleView extends StatelessWidget {
Widget build(BuildContext context) {
 return Center(
  child: Container(
    width: 200,
    height: 200,
    color: Responsive().getResponsiveValue(
        forShortScreen: Colors.yellow,
        context: context),
    // You dodn't need to provide the values for every 
    //parameter(except shortScreen & context)
    // but default its provide the value as ShortScreen for Larger and 

 // utility 
          class Responsive {
            // function reponsible for providing value according to screensize
                {dynamic forShortScreen,
                dynamic forMediumScreen,
                dynamic forLargeScreen,
                dynamic forMobLandScapeMode,
                BuildContext context}) {

              if (isLargeScreen(context)) {

                return forLargeScreen ?? forShortScreen;
              } else if (isMediumScreen(context)) {

                return forMediumScreen ?? forShortScreen;
           else if (isSmallScreen(context) && isLandScapeMode(context)) {

                return forMobLandScapeMode ?? forShortScreen;
              } else {
                return forShortScreen;
            isLandScapeMode(BuildContext context) {
              if (MediaQuery.of(context).orientation == Orientation.landscape) {
                return true;
              } else {
                return false;
            static bool isLargeScreen(BuildContext context) {
              return getWidth(context) > 1200;
            static bool isSmallScreen(BuildContext context) {
              return getWidth(context) < 800;
            static bool isMediumScreen(BuildContext context) {
              return getWidth(context) > 800 && getWidth(context) < 1200;
            static double getWidth(BuildContext context) {
              return MediaQuery.of(context).size.width;

Xcode variables

The best source is probably Apple's official documentation. The specific variable you are looking for is CONFIGURATION.

How do I turn off the output from tar commands on Unix?

Just drop the option v.

-v is for verbose. If you don't use it then it won't display:

tar -zxf tmp.tar.gz -C ~/tmp1

foreach for JSON array , syntax

You can do something like

for(var k in result) {
   console.log(k, result[k]);

which loops over all the keys in the returned json and prints the values. However, if you have a nested structure, you will need to use

typeof result[k] === "object"

to determine if you have to loop over the nested objects. Most APIs I have used, the developers know the structure of what is being returned, so this is unnecessary. However, I suppose it's possible that this expectation is not good for all cases.

Netbeans installation doesn't find JDK

I also had the same problem. So I tried by installing a lesser version say jdk1.5 and running the netbeans installation from command prompt as: Linux: netbeans-5_5-linux.bin -is:javahome /usr/jdk/jdk1.5.0_06 Windows: netbeans-5_5-windows.exe -is:javahome "C:\Program Files\Java\jdk1.5.0_06"

Hope it helps

Options for embedding Chromium instead of IE WebBrowser control with WPF/C#

You've already listed the most notable solutions for embedding Chromium (CEF, Chrome Frame, Awesomium). There aren't any more projects that matter.

There is still the Berkelium project (see Berkelium Sharp and Berkelium Managed), but it emebeds an old version of Chromium.

CEF is your best bet - it's fully open source and frequently updated. It's the only option that allows you to embed the latest version of Chromium. Now that Per Lundberg is actively working on porting CEF 3 to CefSharp, this is the best option for the future. There is also Xilium.CefGlue, but this one provides a low level API for CEF, it binds to the C API of CEF. CefSharp on the other hand binds to the C++ API of CEF.

Adobe is not the only major player using CEF, see other notable applications using CEF on the CEF wikipedia page.

Updating Chrome Frame is pointless since the project has been retired.

Your password does not satisfy the current policy requirements

For MySQL 8*

SET GLOBAL validate_password.policy=LOW

Reference Link to explain about policy - Click Here

What is this CSS selector? [class*="span"]

It selects all elements where the class name contains the string "span" somewhere. There's also ^= for the beginning of a string, and $= for the end of a string. Here's a good reference for some CSS selectors.

I'm only familiar with the bootstrap classes spanX where X is an integer, but if there were other selectors that ended in span, it would also fall under these rules.

It just helps to apply blanket CSS rules.

How to increase the max upload file size in ASP.NET?

I have a blog post on how to increase the file size for asp upload control.

From the post:

By default, the FileUpload control allows a maximum of 4MB file to be uploaded and the execution timeout is 110 seconds. These properties can be changed from within the web.config file’s httpRuntime section. The maxRequestLength property determines the maximum file size that can be uploaded. The executionTimeout property determines the maximum time for execution.

How to use BeginInvoke C#

I guess your code relates to Windows Forms.
You call BeginInvoke if you need something to be executed asynchronously in the UI thread: change control's properties in most of the cases.
Roughly speaking this is accomplished be passing the delegate to some procedure which is being periodically executed. (message loop processing and the stuff like that)

If BeginInvoke is called for Delegate type the delegate is just invoked asynchronously.
(Invoke for the sync version.)

If you want more universal code which works perfectly for WPF and WinForms you can consider Task Parallel Library and running the Task with the according context. (TaskScheduler.FromCurrentSynchronizationContext())

And to add a little to already said by others: Lambdas can be treated either as anonymous methods or expressions.
And that is why you cannot just use var with lambdas: compiler needs a hint.


this requires .Net v4.0 and higher

// This line must be called in UI thread to get correct scheduler
var scheduler = System.Threading.Tasks.TaskScheduler.FromCurrentSynchronizationContext();

// this can be called anywhere
var task = new System.Threading.Tasks.Task( () => someformobj.listBox1.SelectedIndex = 0);

// also can be called anywhere. Task  will be scheduled for execution.
// And *IF I'm not mistaken* can be (or even will be executed synchronously)
// if this call is made from GUI thread. (to be checked) 

If you started the task from other thread and need to wait for its completition task.Wait() will block calling thread till the end of the task.

Read more about tasks here.

Why use $_SERVER['PHP_SELF'] instead of ""

There is no difference. The $_SERVER['PHP_SELF'] just makes the execution time slower by like 0.000001 second.

Java HTML Parsing

The main problem as stated by preceding coments is malformed HTML, so an html cleaner or HTML-XML converter is a must. Once you get the XML code (XHTML) there are plenty of tools to handle it. You could get it with a simple SAX handler that extracts only the data you need or any tree-based method (DOM, JDOM, etc.) that let you even modify original code.

Here is a sample code that uses HTML cleaner to get all DIVs that use a certain class and print out all Text content inside it.

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.htmlcleaner.HtmlCleaner;
import org.htmlcleaner.TagNode;

 * @author Fernando Miguélez Palomo <fernandoDOTmiguelezATgmailDOTcom>
public class TestHtmlParse
    static final String className = "tags";
    static final String url = "";

    TagNode rootNode;

    public TestHtmlParse(URL htmlPage) throws IOException
        HtmlCleaner cleaner = new HtmlCleaner();
        rootNode = cleaner.clean(htmlPage);

    List getDivsByClass(String CSSClassname)
        List divList = new ArrayList();

        TagNode divElements[] = rootNode.getElementsByName("div", true);
        for (int i = 0; divElements != null && i < divElements.length; i++)
            String classType = divElements[i].getAttributeByName("class");
            if (classType != null && classType.equals(CSSClassname))

        return divList;

    public static void main(String[] args)
            TestHtmlParse thp = new TestHtmlParse(new URL(url));

            List divs = thp.getDivsByClass(className);
            System.out.println("*** Text of DIVs with class '"+className+"' at '"+url+"' ***");
            for (Iterator iterator = divs.iterator(); iterator.hasNext();)
                TagNode divElement = (TagNode);
                System.out.println("Text child nodes of DIV: " + divElement.getText().toString());
        catch(Exception e)

how to add a day to a date using jquery datepicker

The datepicker('setDate') sets the date in the datepicket not in the input.

You should add the date and set it in the input.

var date2 = $('.pickupDate').datepicker('getDate');
var nextDayDate = new Date();
nextDayDate.setDate(date2.getDate() + 1);

Change the size of a JTextField inside a JBorderLayout

Try to play with


These method are used by layout when it decide what should be the size of current element. The layout manager calls setSize() and actually overrides your values.

jQuery calculate sum of values in all text fields

$('.price').blur(function () {
    var sum = 0;
    $('.price').each(function() {

            sum += parseFloat($(this).val());


JS Fiddle

mysql delete under safe mode

Googling around, the popular answer seems to be "just turn off safe mode":

DELETE FROM instructor WHERE salary BETWEEN 13000 AND 15000;

If I'm honest, I can't say I've ever made a habit of running in safe mode. Still, I'm not entirely comfortable with this answer since it just assumes you should go change your database config every time you run into a problem.

So, your second query is closer to the mark, but hits another problem: MySQL applies a few restrictions to subqueries, and one of them is that you can't modify a table while selecting from it in a subquery.

Quoting from the MySQL manual, Restrictions on Subqueries:

In general, you cannot modify a table and select from the same table in a subquery. For example, this limitation applies to statements of the following forms:

UPDATE t ... WHERE col = (SELECT ... FROM t ...);

Exception: The preceding prohibition does not apply if you are using a subquery for the modified table in the FROM clause. Example:

UPDATE t ... WHERE col = (SELECT * FROM (SELECT ... FROM t...) AS _t ...);

Here the result from the subquery in the FROM clause is stored as a temporary table, so the relevant rows in t have already been selected by the time the update to t takes place.

That last bit is your answer. Select target IDs in a temporary table, then delete by referencing the IDs in that table:

DELETE FROM instructor WHERE id IN (
    SELECT id FROM instructor WHERE salary BETWEEN 13000 AND 15000
  ) AS temp

SQLFiddle demo.

Remove non-ASCII characters from CSV

I'm using a very minimal busybox system, in which there is no support for ranges in tr or POSIX character classes, so I have to do it the crappy old-fashioned way. Here's the solution with sed, stripping ALL non-printable non-ASCII characters from the file:

sed -i 's/[^a-zA-Z 0-9`~!@#$%^&*()_+\[\]\\{}|;'\'':",.\/<>?]//g' FILE

Pandas index column title or name

To just get the index column names df.index.names will work for both a single Index or MultiIndex as of the most recent version of pandas.

As someone who found this while trying to find the best way to get a list of index names + column names, I would have found this answer useful:

names = list(filter(None, df.index.names + df.columns.values.tolist()))

This works for no index, single column Index, or MultiIndex. It avoids calling reset_index() which has an unnecessary performance hit for such a simple operation. I'm surprised there isn't a built in method for this (that I've come across). I guess I run into needing this more often because I'm shuttling data from databases where the dataframe index maps to a primary/unique key, but is really just another column to me.

How to export a table dataframe in PySpark to csv?

If you cannot use spark-csv, you can do the following: x: ",".join(map(str, x))).coalesce(1).saveAsTextFile("file.csv")

If you need to handle strings with linebreaks or comma that will not work. Use this:

import csv
import cStringIO

def row2csv(row):
    buffer = cStringIO.StringIO()
    writer = csv.writer(buffer)
    writer.writerow([str(s).encode("utf-8") for s in row])

How to install ia32-libs in Ubuntu 14.04 LTS (Trusty Tahr)

sudo -i
cd /etc/apt/sources.list.d
echo "deb precise main restricted universe multiverse" >ia32-libs-raring.list
apt-get update
apt-get install ia32-libs
rm /etc/apt/sources.list.d/ia32-libs-raring.list
apt-get update

If you are in China, you can modify "raring" to "precise" (for Ubuntu 13.04 (Raring Ringtail) and Ubuntu 12.04 LTS (Precise Pangolin), respectively). I installed Beyond Compare on Ubuntu 14.04 (Trusty Tahr).

WebSockets vs. Server-Sent events/EventSource

Opera, Chrome, Safari supports SSE, Chrome, Safari supports SSE inside of SharedWorker Firefox supports XMLHttpRequest readyState interactive, so we can make EventSource polyfil for Firefox

How do I put a clear button inside my HTML text input box like the iPhone does?

It is so simple in HTML5

<input type="search">

This will do your job!

Software Design vs. Software Architecture

In some descriptions of the SDLC (Software Development Life Cycle) they are interchangeable, but the consesus is that they are distinct. They are at the same time: different (1) stages, (2) areas of responsibility, and (3) levels of decision-making.

  • Architecture is the bigger picture: the choice of frameworks, languages, scope, goals, and high-level methodologies (Rational, waterfall, agile, etc.).
  • Design is the smaller picture: the plan for how code will be organized; how the contracts between different parts of the system will look; the ongoing implementation of the project's methodologies and goals. Specification are written during this stage.

These two stages will seem to blend together for different reasons.

  1. Smaller projects often don't have enough scope to separate out planning into these to stages.
  2. A project might be a part of a larger project, and hence parts of both stages are already decided. (There are already existing databases, conventions, standards, protocols, frameworks, reusable code, etc.)
  3. Newer ways of thinking about the SDLC (see Agile methodologies) somewhat rearrange this traditional approach. Design (architecture to a lesser extent) takes place throughout the SDLC on purpose. There are often more iterations where the whole process happens over and over.
  4. Software development is complicated and difficult to plan anyway, but clients/managers/salespeople usually make it harder by changing goals and requirements mid-stream. Design and even architectural decisions must bemade later in the project whether that is the plan or not.

Even if the stages or areas of responsibility blend together and happen all over the place, it is always good to know what level of decision-making is happening. (We could go on forever with this. I'm trying to keep it a summary.) I'll end with: Even if it seems your project has no formal architectural or design stage/AOR/documentaiton, it IS happening whether anyone is consciously doing it or not. If no one decides to do architecture, then a default one happens that is probably poor. Ditto for design. These concepts are almost more important if there are no formal stages representing them.

How can I get the current directory name in Javascript?

This one-liner works:

var currentDirectory = window.location.pathname.split('/').slice(0, -1).join('/')

Why can't static methods be abstract in Java?

Because "abstract" means: "Implements no functionality", and "static" means: "There is functionality even if you don't have an object instance". And that's a logical contradiction.

Create an empty list in python with certain size

The accepted answer has some gotchas. For example:

>>> a = [{}] * 3
>>> a
[{}, {}, {}]
>>> a[0]['hello'] = 5
>>> a
[{'hello': 5}, {'hello': 5}, {'hello': 5}]

So each dictionary refers to the same object. Same holds true if you initialize with arrays or objects.

You could do this instead:

>>> b = [{} for i in range(0, 3)]
>>> b
[{}, {}, {}]
>>> b[0]['hello'] = 6
>>> b
[{'hello': 6}, {}, {}]

c++ custom compare function for std::sort()

Your comparison function is not even wrong.

Its arguments should be the type stored in the range, i.e. std::pair<K,V>, not const void*.

It should return bool not a positive or negative value. Both (bool)1 and (bool)-1 are true so your function says every object is ordered before every other object, which is clearly impossible.

You need to model the less-than operator, not strcmp or memcmp style comparisons.

See StrictWeakOrdering which describes the properties the function must meet.

border-radius not working

if you have parent element than your parent element must have overflow: hidden; property because if your children content is getting oveflowed from parent border than your border will be visible .otherwise your borderradius is working but it is hide by your children content.

.outer {
  width: 200px;
  height: 120px;
  border: 1px solid black;
  margin-left: 50px;
  overflow: hidden;
  border-radius: 30px;
.inner1 {
  width: 100%;
  height: 100%;
  background-image: linear-gradient(#FF9933,white, green);
  border: 1px solid black;
<div class="outer">
  <div class="inner1">

How to upload folders on GitHub

This is Web GUI of a GitHub repository:

enter image description here

Drag and drop your folder to the above area. When you upload too much folder/files, GitHub will notice you:

Yowza, that’s a lot of files. Try again with fewer than 100 files.

enter image description here

and add commit message

enter image description here

And press button Commit changes is the last step.

Catching multiple exception types in one catch block

A great way is to use set_exception_handler.

Warning!!! with PHP 7, you might get a white screen of death for fatal errors. For example, if you call a method on a non-object you would normally get Fatal error: Call to a member function your_method() on null and you would expect to see this if error reporting is on.

The above error will NOT be caught with catch(Exception $e). The above error will NOT trigger any custom error handler set by set_error_handler.

You must use catch(Error $e){ } to catch errors in PHP7. . This could help:

class ErrorHandler{
    public static function excep_handler($e)

HTTP Error 500.19 and error code : 0x80070021

In our case, we struggled with this error for quite some days. It turns out that in control panel, programs, turn windows features on or off.

We selected Internet Information Services, world wide web services, Application development features and there we check the set of features associated with our development environment. For example: ASP.NET 4.6. .NET Extensibility 4.6, etc.

It works!

Vertically align text within input field of fixed-height without display: table or padding?

I ran into this problem myself. I found that not specifying an input height, but using the font-height and padding combined, results in vertically aligned text.

For instance, lets say you want to have a 42px tall input box, with a font-size of 20px. You could simply find the difference between the input height and the font-size, divide it by two, and set your padding to that amount. In this case, you would have 22px total worth of padding, which is 11px on each side.

<input type="text" style="padding: 11px 0px 11px 0px; font-size: 20px;" />

That would give you a 42px tall input box with perfect vertical alignment.

Hope that helps.

Set custom attribute using JavaScript

Please use dataset

var article = document.querySelector('#electriccars'),
    data = article.dataset;

// data.columns -> "3"
// data.indexnumber -> "12314"
// data.parent -> "cars"

so in your case for setting data:

getElementById('item1').dataset.icon = "base2.gif";

iPhone UILabel text soft shadow

To keep things up to date: Creating the shadow in Swift is as easy as that:

Import the QuartzCore Framework

import QuartzCore

And set the shadow attributes to your label

titleLabel.shadowColor = UIColor.blackColor()
titleLabel.shadowOffset = CGSizeMake(0.0, 0.0)
titleLabel.layer.shadowRadius = 5.0
titleLabel.layer.shadowOpacity = 0.8
titleLabel.layer.masksToBounds = false
titleLabel.layer.shouldRasterize = true

Mapping US zip code to time zone

Ruby gem to convert zip code to timezone: (forked from

> ActiveSupport::TimeZone.find_by_zipcode('90029')
 => "Pacific Time (US & Canada)"

It's fast, small, and has no external dependencies, but keep in mind that zip codes just don't map perfectly to timezones.

Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 71 bytes)

WordPress overrides PHP's memory limit to 256M, with the assumption that whatever it was set to before is going to be too low to render the dashboard. You can override this by defining WP_MAX_MEMORY_LIMIT in wp-config.php:

define( 'WP_MAX_MEMORY_LIMIT' , '512M' );

I agree with DanFromGermany, 256M is really a lot of memory for rendering a dashboard page. Changing the memory limit is really putting a bandage on the problem.

Omitting the second expression when using the if-else shorthand

Another option:

x === 2 ? doSomething() : void 0;

How can I pass arguments to anonymous functions in JavaScript?

Event handlers expect one parameter which is the event that was fired. You happen to be renaming that to 'myMessage' and therefore you are alerting the event object rather than your message.

A closure can allow you to reference the variable you have defined outside the function however if you are using Jquery you may want to look at its event specific API e.g.

This has an option for passing in your own data.

Refresh/reload the content in Div using jquery/ajax

$(document).ready(function() {
var pageRefresh = 5000; //5 s
    setInterval(function() {
    }, pageRefresh);

// Functions

function refresh() {
    $('#div1').load(location.href + " #div1");
    $('#div2').load(location.href + " #div2");

"The Controls collection cannot be modified because the control contains code blocks"

I had same issue in the user control. My page that was hosting the control had comments in the head tag, I removed those comments, everything worked afterwards. Some posts also suggest removing scripts from head and placing them in the body.

LINQ to Entities does not recognize the method

If anyone is looking for a VB.Net answer (as I was initially), here it is:

Public Function IsSatisfied() As Expression(Of Func(Of Charity, String, String, Boolean))

Return Function(charity, name, referenceNumber) (String.IsNullOrWhiteSpace(name) Or
                                                         charity.registeredName.ToLower().Contains(name.ToLower()) Or
                                                         charity.alias.ToLower().Contains(name.ToLower()) Or
                                                         charity.charityId.ToLower().Contains(name.ToLower())) And
                                                    (String.IsNullOrEmpty(referenceNumber) Or
End Function

Check for file exists or not in sql server?

Not tested but you can try something like this :

Declare @count as int
Set @count=1
Declare @inputFile varchar(max)
Declare @Sample Table
(id int,filepath varchar(max) ,Isexists char(3))

while @count<(select max(id) from yourTable)
Set @inputFile =(Select filepath from yourTable where id=@count)
exec master.dbo.xp_fileexist @inputFile , 
@isExists OUTPUT
insert into @Sample
Select @count,@inputFile ,case @isExists 
when 1 then 'Yes' 
else 'No' 
end as isExists
set @count=@count+1

Shell Script: How to write a string to file and to stdout on console?

Use the tee command:

echo "hello" | tee logfile.txt

git: can't push (unpacker error) related to permission issues

I use gitosis for managing this kind of stuff. Gitosis has a single user (usually called "git") that owns all the repositories, and it uses public-key-based access control to each repo. It might not suit your setup but is probably worth checking out (no pun intended).

How do you run a .exe with parameters using vba's shell()?

The below code will help you to auto open the .exe file from excel...

Sub Auto_Open()

    Dim x As Variant
    Dim Path As String

    ' Set the Path variable equal to the path of your program's installation
    Path = "C:\Program Files\\Alien Shooter\game.exe"
    x = Shell(Path, vbNormalFocus)

End Sub

Export and import table dump (.sql) using pgAdmin

follow he steps. in pgadmin

host-DataBase-Schemas- public (click right) CREATE script- open file -(choose xxx.sql) , then click over the option execute query write result to file -export data file ok- then click in save.its all. it work to me.

note: error in version command script enter image description herede sql over pgadmin can be search, example:

enter image description here

Curl error 60, SSL certificate issue: self signed certificate in certificate chain

Answers suggesting to disable CURLOPT_SSL_VERIFYPEER should not be accepted. The question is "Why doesn't it work with cURL", and as correctly pointed out by Martijn Hols, it is dangerous.

The error is probably caused by not having an up-to-date bundle of CA root certificates. This is typically a text file with a bunch of cryptographic signatures that curl uses to verify a host’s SSL certificate.

You need to make sure that your installation of PHP has one of these files, and that it’s up to date (otherwise download one here:

Then set in php.ini:

curl.cainfo = <absolute_path_to> cacert.pem

If you are setting it at runtime, use:

curl_setopt ($ch, CURLOPT_CAINFO, dirname(__FILE__)."/cacert.pem");

npm - how to show the latest version of a package

There is also another easy way to check the latest version without going to NPM if you are using VS Code.

In package.json file check for the module you want to know the latest version. Remove the current version already present there and do CTRL + space or CMD + space(mac).The VS code will show the latest versions

image shows the latest versions of modules in vscode

Display rows with one or more NaN values in pandas dataframe

You can use DataFrame.any with parameter axis=1 for check at least one True in row by DataFrame.isna with boolean indexing:

df1 = df[df.isna().any(axis=1)]

d = {'filename': ['M66_MI_NSRh35d32kpoints.dat', 'F71_sMI_DMRI51d.dat', 'F62_sMI_St22d7.dat', 'F41_Car_HOC498d.dat', 'F78_MI_547d.dat'], 'alpha1': [0.8016, 0.0, 1.721, 1.167, 1.897], 'alpha2': [0.9283, 0.0, 3.833, 2.809, 5.459], 'gamma1': [1.0, np.nan, 0.23748000000000002, 0.36419, 0.095319], 'gamma2': [0.074804, 0.0, 0.15, 0.3, np.nan], 'chi2min': [39.855990000000006, 1e+25, 10.91832, 7.966335000000001, 25.93468]}
df = pd.DataFrame(d).set_index('filename')

print (df)
                             alpha1  alpha2    gamma1    gamma2       chi2min
M66_MI_NSRh35d32kpoints.dat  0.8016  0.9283  1.000000  0.074804  3.985599e+01
F71_sMI_DMRI51d.dat          0.0000  0.0000       NaN  0.000000  1.000000e+25
F62_sMI_St22d7.dat           1.7210  3.8330  0.237480  0.150000  1.091832e+01
F41_Car_HOC498d.dat          1.1670  2.8090  0.364190  0.300000  7.966335e+00
F78_MI_547d.dat              1.8970  5.4590  0.095319       NaN  2.593468e+01


print (df.isna())
                            alpha1 alpha2 gamma1 gamma2 chi2min
M66_MI_NSRh35d32kpoints.dat  False  False  False  False   False
F71_sMI_DMRI51d.dat          False  False   True  False   False
F62_sMI_St22d7.dat           False  False  False  False   False
F41_Car_HOC498d.dat          False  False  False  False   False
F78_MI_547d.dat              False  False  False   True   False

print (df.isna().any(axis=1))
M66_MI_NSRh35d32kpoints.dat    False
F71_sMI_DMRI51d.dat             True
F62_sMI_St22d7.dat             False
F41_Car_HOC498d.dat            False
F78_MI_547d.dat                 True
dtype: bool

df1 = df[df.isna().any(axis=1)]
print (df1)
                     alpha1  alpha2    gamma1  gamma2       chi2min
F71_sMI_DMRI51d.dat   0.000   0.000       NaN     0.0  1.000000e+25
F78_MI_547d.dat       1.897   5.459  0.095319     NaN  2.593468e+01

Show/Hide the console window of a C# console application

You could do the reversed and set the Application output type to: Windows Application. Then add this code to the beginning of the application.

[DllImport("kernel32.dll", EntryPoint = "GetStdHandle", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern IntPtr GetStdHandle(int nStdHandle);

[DllImport("kernel32.dll", EntryPoint = "AllocConsole", SetLastError = true, CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern int AllocConsole();

private const int STD_OUTPUT_HANDLE = -11;
private const int MY_CODE_PAGE = 437;
private static bool showConsole = true; //Or false if you don't want to see the console

static void Main(string[] args)
    if (showConsole)
        IntPtr stdHandle = GetStdHandle(STD_OUTPUT_HANDLE);
        Microsoft.Win32.SafeHandles.SafeFileHandle safeFileHandle = new Microsoft.Win32.SafeHandles.SafeFileHandle(stdHandle, true);
        FileStream fileStream = new FileStream(safeFileHandle, FileAccess.Write);
        System.Text.Encoding encoding = System.Text.Encoding.GetEncoding(MY_CODE_PAGE);
        StreamWriter standardOutput = new StreamWriter(fileStream, encoding);
        standardOutput.AutoFlush = true;

    //Your application code

This code will show the Console if showConsole is true

Delete duplicate elements from an array

var arr = [1,2,2,3,4,5,5,5,6,7,7,8,9,10,10];

function squash(arr){
    var tmp = [];
    for(var i = 0; i < arr.length; i++){
        if(tmp.indexOf(arr[i]) == -1){
    return tmp;


Working Example

Compatibility for indexOf on old browsers

EnterKey to press button in VBA Userform

You could also use the TextBox's On Key Press event handler:

'Keycode for "Enter" is 13
Private Sub TextBox1_KeyDown(KeyCode As Integer, Shift As Integer)
    If KeyCode = 13 Then
    End If
End Sub

Textbox1 is an example. Make sure you choose the textbox you want to refer to and also Logincode_Click is an example sub which you call (run) with this code. Make sure you refer to your preferred sub

Error "package does not exist"

It is 2020 December. The same problem came to me in a different way. When I was going to Deploy in google play store, it said I have to create the bundle higher than android v28 and I updated my projects Compile using Android Version 30 (in Xamarin Android project properties). It was not possible to do it with the same error (Android support library has no support for V7). I tried everything mentioned above and was not working and here is what worked for me. I was using this in splashactivity.cs

using Android.Support.V7.App;

And it is the one giving the trouble and i changed it into V4

using Android.Support.V4.App;

then AppCompatActivity was underlined red and I had to get androidx appcompat app as follows

using AndroidX.AppCompat.App;

Now it is working and it may help someone else too.

Can I write native iPhone apps using Python?

Yes you can. You write your code in tinypy (which is restricted Python), then use tinypy to convert it to C++, and finally compile this with XCode into a native iPhone app. Phil Hassey has published a game called Elephants! using this approach. Here are more details,

String concatenation in Ruby

You can concatenate in string definition directly:

nombre_apellido = "#{customer['first_name']} #{customer['last_name']} #{order_id}"

SQL query to make all data in a column UPPER CASE?


  MyColumn = UPPER(MyColumn)


  UPPER(MyColumn) AS MyColumn

How to use protractor to check if an element is visible?

To wait for visibility

const EC = protractor.ExpectedConditions;
browser.wait(EC.visibilityOf(element(by.css('.icon-spinner icon-spin ng-hide')))).then(function() {
  //do stuff

Xpath trick to only find visible elements

element(by.xpath('//i[not(contains(@style,"display:none")) and @class="icon-spinner icon-spin ng-hide"]))

Replace deprecated preg_replace /e with preg_replace_callback

You can use an anonymous function to pass the matches to your function:

$result = preg_replace_callback(
    function($m) { return CallFunction($m[1], $m[2], $m[3], $m[4], $m[5]); },

Apart from being faster, this will also properly handle double quotes in your string. Your current code using /e would convert a double quote " into \".

How to remove a directory from git repository?

First git command need to know who you are before deleting anything

  1. git init
  2. git config "someone"
  3. git config "[email protected]"
  4. git rm -r
  5. git commit -m "deleting dir"
  6. git push origin master

ReadFile in Base64 Nodejs

I think that the following example demonstrates what you need:

The essence of the article is this code part:

var fs = require('fs');

// function to encode file data to base64 encoded string
function base64_encode(file) {
    // read binary data
    var bitmap = fs.readFileSync(file);
    // convert binary data to base64 encoded string
    return new Buffer(bitmap).toString('base64');

// function to create file from base64 encoded string
function base64_decode(base64str, file) {
    // create buffer object from base64 encoded string, it is important to tell the constructor that the string is base64 encoded
    var bitmap = new Buffer(base64str, 'base64');
    // write buffer to file
    fs.writeFileSync(file, bitmap);
    console.log('******** File created from base64 encoded string ********');

// convert image to base64 encoded string
var base64str = base64_encode('kitten.jpg');
// convert base64 string back to image 
base64_decode(base64str, 'copy.jpg');

Make header and footer files to be included in multiple html pages

I think, answers to this question are too old... currently some desktop and mobile browsers support HTML Templates for doing this.

I've built a little example:

Tested OK in Chrome 61.0, Opera 48.0, Opera Neon 1.0, Android Browser 6.0, Chrome Mobile 61.0 and Adblocker Browser 54.0
Tested KO in Safari 10.1, Firefox 56.0, Edge 38.14 and IE 11

More compatibility info in


<!DOCTYPE html>
<html lang="en">
    <meta charset="UTF-8">
    <title>HTML Template Example</title>

    <link rel="stylesheet" href="styles.css">
    <link rel="import" href="autoload-template.html">

<div class="template-container">1</div>
<div class="template-container">2</div>
<div class="template-container">3</div>
<div class="template-container">4</div>
<div class="template-container">5</div>



<span id="template-content">
    Template Hello World!

    var me = document.currentScript.ownerDocument;
    var post = me.querySelector( '#template-content' );

    var container = document.querySelectorAll( '.template-container' );

    //alert( container.length );
    for(i=0; i<container.length ; i++) {
        container[i].appendChild( post.cloneNode( true ) );


#template-content {
    color: red;

.template-container {
    background-color: yellow;
    color: blue;

Your can get more examples in this HTML5 Rocks post

"Logging out" of phpMyAdmin?

The presence of the logout button depends on whether you are required to login or not, in the first place. This is tweakable in PHPMyAdmin config files.

Yet, I don't think that would change anything concerning your error message. You would need to fix the configuration for the message to go away.

Edit: this is the kind of solution you should be searching for. And here are plenty of others for you to explore ^^

What does %s mean in a python format string?

In answer to your second question: What does this code do?...

This is fairly standard error-checking code for a Python script that accepts command-line arguments.

So the first if statement translates to: if you haven't passed me an argument, I'm going to tell you how you should pass me an argument in the future, e.g. you'll see this on-screen:

Usage: database-name

The next if statement checks to see if the 'database-name' you passed to the script actually exists on the filesystem. If not, you'll get a message like this:

ERROR: Database database-name was not found!

From the documentation:

argv[0] is the script name (it is operating system dependent whether this is a full pathname or not). If the command was executed using the -c command line option to the interpreter, argv[0] is set to the string '-c'. If no script name was passed to the Python interpreter, argv[0] is the empty string.

Using PUT method in HTML form

If you are using nodejs, you can install the package method-override that lets you do this using a middleware. Link to documentation:

After installing this, all I had to do was the following:

var methodOverride = require('method-override')

send/post xml file using curl command line

Here's how you can POST XML on Windows using curl command line on Windows. Better use batch/.cmd file for that:

curl -i -X POST -H "Content-Type: text/xml" -d             ^
"^<?xml version=\"1.0\" encoding=\"UTF-8\" ?^>                ^
    ^<Transaction^>                                           ^
        ^<SomeParam1^>Some-Param-01^</SomeParam1^>            ^
        ^<Password^>SomePassW0rd^</Password^>                 ^
        ^<Transaction_Type^>00^</Transaction_Type^>           ^
        ^<CardHoldersName^>John Smith^</CardHoldersName^>     ^
        ^<DollarAmount^>9.97^</DollarAmount^>                 ^
        ^<Card_Number^>4111111111111111^</Card_Number^>       ^
        ^<Expiry_Date^>1118^</Expiry_Date^>                   ^
        ^<VerificationStr2^>123^</VerificationStr2^>          ^
        ^<CVD_Presence_Ind^>1^</CVD_Presence_Ind^>            ^
        ^<Reference_No^>Some Reference Text^</Reference_No^>  ^
        ^<Client_Email^>[email protected]^</Client_Email^>       ^
        ^<Client_IP^>^</Client_IP^>                 ^
        ^<Tax1Amount^>^</Tax1Amount^>                         ^
        ^<Tax2Amount^>^</Tax2Amount^>                         ^
    ^</Transaction^>                                          ^
" "http://localhost:8080"

AngularJS : Clear $watch

Ideally, every custom watch should be removed when you leave the scope.

It helps in better memory management and better app performance.

// call to $watch will return a de-register function
var listener = $scope.$watch(someVariableToWatch, function(....));

$scope.$on('$destroy', function() {
    listener(); // call the de-register function on scope destroy

How to get file creation & modification date/times in Python?

In Python 3.4 and above, you can use the object oriented pathlib module interface which includes wrappers for much of the os module. Here is an example of getting the file stats.

>>> import pathlib
>>> fname = pathlib.Path('')
>>> assert fname.exists(), f'No such file: {fname}'  # check that the file exists
>>> print(fname.stat())
os.stat_result(st_mode=33206, st_ino=5066549581564298, st_dev=573948050, st_nlink=1, st_uid=0, st_gid=0, st_size=413, st_atime=1523480272, st_mtime=1539787740, st_ctime=1523480272)

For more information about what os.stat_result contains, refer to the documentation. For the modification time you want fname.stat().st_mtime:

>>> import datetime
>>> mtime = datetime.datetime.fromtimestamp(fname.stat().st_mtime)
>>> print(mtime)
datetime.datetime(2018, 10, 17, 10, 49, 0, 249980)

If you want the creation time on Windows, or the most recent metadata change on Unix, you would use fname.stat().st_ctime:

>>> ctime = datetime.datetime.fromtimestamp(fname.stat().st_ctime)
>>> print(ctime)
datetime.datetime(2018, 4, 11, 16, 57, 52, 151953)

This article has more helpful info and examples for the pathlib module.

Is it possible to put CSS @media rules inline?

I tried to test this and it did not seem to work but I'm curious why Apple is using it. I was just on and noticed in the generated code it provides if you select the 'Large Button' radio button, they are using an inline media query.

<a href="#" 
        background:url(#.png) no-repeat;
        @media only screen{

note: added line-breaks for readability, original generated code is minified

New warnings in iOS 9: "all bitcode will be dropped"

Method canOpenUrl is in iOS 9 (due to privacy) changed and is not free to use any more. Your banner provider checks for installed apps so that they do not show banners for an app that is already installed.

That gives all the log statements like

-canOpenURL: failed for URL: "kindle://home" - error: "This app is not allowed to query for scheme kindle"

The providers should update their logic for this.

If you need to query for installed apps/available schemes you need to add them to your info.plist file.

Add the key 'LSApplicationQueriesSchemes' to your plist as an array. Then add strings in that array like 'kindle'.

Of course this is not really an option for the banner ads (since those are dynamic), but you can still query that way for your own apps or specific other apps like Twitter and Facebook.

Documentation of the canOpenUrl: method canOpenUrl:

Documentation about the LSApplicationQueriesSchemes key

Can't find bundle for base name /Bundle, locale en_US

I had the same problem using Netbeans. I went to the project folder and copied the properties file. I think clicked "build" and then "classes." I added the properties file in that folder. That solved my problem.

How do I zip two arrays in JavaScript?

Use the map method:

var a = [1, 2, 3]_x000D_
var b = ['a', 'b', 'c']_x000D_
var c =, i) {_x000D_
  return [e, b[i]];_x000D_


Python - Dimension of Data Frame

Summary of all ways to get info on dimensions of DataFrame or Series

There are a number of ways to get information on the attributes of your DataFrame or Series.

Create Sample DataFrame and Series

df = pd.DataFrame({'a':[5, 2, np.nan], 'b':[ 9, 2, 4]})

     a  b
0  5.0  9
1  2.0  2
2  NaN  4

s = df['a']

0    5.0
1    2.0
2    NaN
Name: a, dtype: float64

shape Attribute

The shape attribute returns a two-item tuple of the number of rows and the number of columns in the DataFrame. For a Series, it returns a one-item tuple.

(3, 2)


len function

To get the number of rows of a DataFrame or get the length of a Series, use the len function. An integer will be returned.



size attribute

To get the total number of elements in the DataFrame or Series, use the size attribute. For DataFrames, this is the product of the number of rows and the number of columns. For a Series, this will be equivalent to the len function:



ndim attribute

The ndim attribute returns the number of dimensions of your DataFrame or Series. It will always be 2 for DataFrames and 1 for Series:



The tricky count method

The count method can be used to return the number of non-missing values for each column/row of the DataFrame. This can be very confusing, because most people normally think of count as just the length of each row, which it is not. When called on a DataFrame, a Series is returned with the column names in the index and the number of non-missing values as the values.

df.count() # by default, get the count of each column

a    2
b    3
dtype: int64

df.count(axis='columns') # change direction to get count of each row

0    2
1    2
2    1
dtype: int64

For a Series, there is only one axis for computation and so it just returns a scalar:


Use the info method for retrieving metadata

The info method returns the number of non-missing values and data types of each column

<class 'pandas.core.frame.DataFrame'>
RangeIndex: 3 entries, 0 to 2
Data columns (total 2 columns):
a    2 non-null float64
b    3 non-null int64
dtypes: float64(1), int64(1)
memory usage: 128.0 bytes

printing a value of a variable in postgresql

You can raise a notice in Postgres as follows:

raise notice 'Value: %', deletedContactId;

Read here

Repository Pattern Step by Step Explanation

As a summary, I would describe the wider impact of the repository pattern. It allows all of your code to use objects without having to know how the objects are persisted. All of the knowledge of persistence, including mapping from tables to objects, is safely contained in the repository.

Very often, you will find SQL queries scattered in the codebase and when you come to add a column to a table you have to search code files to try and find usages of a table. The impact of the change is far-reaching.

With the repository pattern, you would only need to change one object and one repository. The impact is very small.

Perhaps it would help to think about why you would use the repository pattern. Here are some reasons:

  • You have a single place to make changes to your data access

  • You have a single place responsible for a set of tables (usually)

  • It is easy to replace a repository with a fake implementation for testing - so you don't need to have a database available to your unit tests

There are other benefits too, for example, if you were using MySQL and wanted to switch to SQL Server - but I have never actually seen this in practice!

Configure Nginx with proxy_pass

Give this a try...

server {
    listen   80;
    access_log off;
    location / {
        proxy_pass http://IP:8080;
        proxy_set_header    Host            $host;
        proxy_set_header    X-Real-IP       $remote_addr;
        proxy_set_header    X-Forwarded-for $remote_addr;
        port_in_redirect off;
        proxy_redirect   http://IP:8080/jira  /;
        proxy_connect_timeout 300;

    location ~ ^/stash {
        proxy_pass http://IP:7990;
        proxy_set_header    Host            $host;
        proxy_set_header    X-Real-IP       $remote_addr;
        proxy_set_header    X-Forwarded-for $remote_addr;
        port_in_redirect off;
        proxy_redirect   http://IP:7990/  /stash;
        proxy_connect_timeout 300;

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/local/nginx/html;

Passing enum or object through an intent (the best solution)

you can use enum constructor for enum to have primitive data type..

public enum DaysOfWeek {

    private int value;
    private DaysOfWeek(int value) {
        this.value = value;

    public int getValue() {
        return this.value;

    private static final SparseArray<DaysOfWeek> map = new SparseArray<DaysOfWeek>();

         for (DaysOfWeek daysOfWeek : DaysOfWeek.values())
              map.put(daysOfWeek.value, daysOfWeek);

    public static DaysOfWeek from(int value) {
        return map.get(value);

you can use to pass int as extras then pull it from enum using its value.

Can an AJAX response set a cookie?

For the record, be advised that all of the above is (still) true only if the AJAX call is made on the same domain. If you're looking into setting cookies on another domain using AJAX, you're opening a totally different can of worms. Reading cross-domain cookies does work, however (or at least the server serves them; whether your client's UA allows your code to access them is, again, a different topic; as of 2014 they do).

Get variable from PHP to JavaScript

var i = "<?php echo $j; ?>";
//Do something
echo $j;

This is the easiest way of passing a php variable to javascript without Ajax.

You can also use something like this:

var i = "<?php echo json_encode($j); ?>";

This said to be safer or more secure. i think

In Bash, how can I check if a string begins with some value?

I prefer the other methods already posted, but some people like to use:

case "$HOST" in 
            echo "yes";;
            echo "no";;


I've added your alternates to the case statement above

In your edited version you have too many brackets. It should look like this:

if [[ $HOST == user1 || $HOST == node* ]];

Where to find the complete definition of off_t type?

As the "GNU C Library Reference Manual" says

    This is a signed integer type used to represent file sizes. 
    In the GNU C Library, this type is no narrower than int.
    If the source is compiled with _FILE_OFFSET_BITS == 64 this 
    type is transparently replaced by off64_t.


    This type is used similar to off_t. The difference is that 
    even on 32 bit machines, where the off_t type would have 32 bits,
    off64_t has 64 bits and so is able to address files up to 2^63 bytes
    in length. When compiling with _FILE_OFFSET_BITS == 64 this type 
    is available under the name off_t.

Thus if you want reliable way of representing file size between client and server, you can:

  1. Use off64_t type and stat64() function accordingly (as it fills structure stat64, which contains off64_t type itself). Type off64_t guaranties the same size on 32 and 64 bit machines.
  2. As was mentioned before compile your code with -D_FILE_OFFSET_BITS == 64 and use usual off_t and stat().
  3. Convert off_t to type int64_t with fixed size (C99 standard). Note: (my book 'C in a Nutshell' says that it is C99 standard, but optional in implementation). The newest C11 standard says: Exact-width integer types

    1 The typedef name intN_t designates a signed integer type with width N ,
    no padding bits, and a two’s complement representation. Thus, int8_t 
    denotes such a signed integer type with a width of exactly 8 bits.
    without mentioning.

And about implementation:

7.20 Integer types <stdint.h>

    ... An implementation shall provide those types described as ‘‘required’’,
    but need not provide any of the others (described as ‘‘optional’’).
    The following types are required:
    int_least8_t  uint_least8_t
    int_least16_t uint_least16_t
    int_least32_t uint_least32_t
    int_least64_t uint_least64_t
    All other types of this form are optional.

Thus, in general, C standard can't guarantee types with fixed sizes. But most compilers (including gcc) support this feature.

When do I need to do "git pull", before or after "git add, git commit"?

Best way for me is:

  1. create new branch, checkout to it
  2. create or modify files, git add, git commit
  3. back to master branch and do pull from remote (to get latest master changes)
  4. merge newly created branch with master
  5. remove newly created branch
  6. push master to remote

Or you can push newly created branch on remote and merge there (if you do it this way, at the end you need to pull from remote master)

Convert data.frame column format from character to factor

Hi welcome to the world of R.

mtcars  #look at this built in data set
str(mtcars) #allows you to see the classes of the variables (all numeric)

#one approach it to index with the $ sign and the as.factor function
mtcars$am <- as.factor(mtcars$am)
#another approach
mtcars[, 'cyl'] <- as.factor(mtcars[, 'cyl'])
str(mtcars)  # now look at the classes

This also works for character, dates, integers and other classes

Since you're new to R I'd suggest you have a look at these two websites:

R reference manuals:

R Reference card:

Angular 2 / 4 / 5 - Set base href dynamically

I use the current working directory ./ when building several apps off the same domain:

<base href="./">

On a side note, I use .htaccess to assist with my routing on page reload:

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule .* index.html [L]

XPath test if node value is number

I'm not trying to provide a yet another alternative solution, but a "meta view" to this problem.

Answers already provided by Oded and Dimitre Novatchev are correct but what people really might mean with phrase "value is a number" is, how would I say it, open to interpretation.

In a way it all comes to this bizarre sounding question: "how do you want to express your numeric values?"

XPath function number() processes numbers that have

  • possible leading or trailing whitespace
  • preceding sign character only on negative values
  • dot as an decimal separator (optional for integers)
  • all other characters from range [0-9]

Note that this doesn't include expressions for numerical values that

  • are expressed in exponential form (e.g. 12.3E45)
  • may contain sign character for positive values
  • have a distinction between positive and negative zero
  • include value for positive or negative infinity

These are not just made up criteria. An element with content that is according to schema a valid xs:float value might contain any of the above mentioned characteristics. Yet number() would return value NaN.

So answer to your question "How i can check with XPath if a node value is number?" is either "Use already mentioned solutions using number()" or "with a single XPath 1.0 expression, you can't". Think about the possible number formats you might encounter, and if needed, write some kind of logic for validation/number parsing. Within XSLT processing, this can be done with few suitable extra templates, for example.

PS. If you only care about non-zero numbers, the shortest test is

<xsl:if test="number(myNode)">
    <!-- myNode is a non-zero number -->

Plotting images side by side using matplotlib

If the images are in an array and you want to iterate through each element and print it, you can write the code as follows:

plt.figure(figsize=(10,10)) # specifying the overall grid size

for i in range(25):
    plt.subplot(5,5,i+1)    # the number of images in the grid is 5*5 (25)

Also note that I used subplot and not subplots. They're both different

Python 3: UnboundLocalError: local variable referenced before assignment

Why not simply return your calculated value and let the caller modify the global variable. It's not a good idea to manipulate a global variable within a function, as below:

Var1 = 1
Var2 = 0

def function(): 
    if Var2 == 0 and Var1 > 0:
        print("Result One")
    elif Var2 == 1 and Var1 > 0:
        print("Result Two")
    elif Var1 < 1:
        print("Result Three")
    return Var1 - 1

Var1 = function()

or even make local copies of the global variables and work with them and return the results which the caller can then assign appropriately

def function():
v1, v2 = Var1, Var2
# calculate using the local variables v1 & v2
return v1 - 1

Var1 = function()

What is a superfast way to read large files line-by-line in VBA?

Line Input works fine for small files. However, when file sizes reach around 90k, Line Input jumps all over the place and reads data in the wrong order from the source file. I tested it with different filesizes:

49k = ok
60k = ok
78k = ok
85k = ok
93k = error
101k = error
127k = error
156k = error

Lesson learned - use Scripting.FileSystemObject

'if' statement in jinja2 template

Why the loop?

You could simply do this:

{% if 'priority' in data %}
    <p>Priority: {{ data['priority'] }}</p>
{% endif %}

When you were originally doing your string comparison, you should have used == instead.

How to support HTTP OPTIONS verb in ASP.NET MVC/WebAPI application

    protected void Application_EndRequest()
        if (Context.Response.StatusCode == 405 && Context.Request.HttpMethod == "OPTIONS" )
            Response.StatusCode = 200;

enabling cross-origin resource sharing on IIS7

The 405 response is a "Method not allowed" response. It sounds like your server isn't properly configured to handle CORS preflight requests. You need to do two things:

1) Enable IIS7 to respond to HTTP OPTIONS requests. You are getting the 405 because IIS7 is rejecting the OPTIONS request. I don't know how to do this as I'm not familiar with IIS7, but there are probably others on Stack Overflow who do.

2) Configure your application to respond to CORS preflight requests. You can do this by adding the following two lines underneath the Access-Control-Allow-Origin line in the <customHeaders> section:

<add name="Access-Control-Allow-Methods" value="GET,PUT,POST,DELETE" />
<add name="Access-Control-Allow-Headers" value="Content-Type" />

You may have to add other values to the Access-Control-Allow-Headers section based on what headers your request is asking for. Do you have the sample code for making a request?

You can learn more about CORS and CORS preflight here:

Live Video Streaming with PHP

There are a lot of "off-the-shelf" 'servers' that will run in your environment. Most of these utilize the aforementioned Flex or Silverlight to implement the actual video itself but I'm pretty sure all will run under LAMP/PHP.

The challenges will picking the best software from everything that's available and getting your hosting-provider to let you stream video (it goes without saying that streaming is heavy on bandwidth).

How to Get a Specific Column Value from a DataTable?

I suppose you could use a DataView object instead, this would then allow you to take advantage of the RowFilter property as explained here:

private void MakeDataView() 
    DataView view = new DataView();

    view.Table = DataSet1.Tables["Countries"];
    view.RowFilter = "CountryName = 'France'";
    view.RowStateFilter = DataViewRowState.ModifiedCurrent;

    // Simple-bind to a TextBox control
    Text1.DataBindings.Add("Text", view, "CountryID");

How to find out the server IP address (using JavaScript) that the browser is connected to?

I am sure the following code will help you to get ip address.

<script type="application/javascript">
    function getip(json){
      alert(json.ip); // alerts the ip address

<script type="application/javascript" src=""></script>

Best way to deploy Visual Studio application that can run without installing

It is possible and is deceptively easy:

  1. "Publish" the application (to, say, some folder on drive C), either from menu Build or from the project's properties ? Publish. This will create an installer for a ClickOnce application.
  2. But instead of using the produced installer, find the produced files (the EXE file and the .config, .manifest, and .application files, along with any DLL files, etc.) - they are all in the same folder and typically in the bin\Debug folder below the project file (.csproj).
  3. Zip that folder (leave out any *.vhost.* files and the app.publish folder (they are not needed), and the .pdb files unless you foresee debugging directly on your user's system (for example, by remote control)), and provide it to the users.

An added advantage is that, as a ClickOnce application, it does not require administrative privileges to run (if your application follows the normal guidelines for which folders to use for application data, etc.).

As for .NET, you can check for the minimum required version of .NET being installed (or at all) in the application (most users will already have it installed) and present a dialog with a link to the download page on the Microsoft website (or point to one of your pages that could redirect to the Microsoft page - this makes it more robust if the Microsoft URL change). As it is a small utility, you could target .NET 2.0 to reduce the probability of a user to have to install .NET.

It works. We use this method during development and test to avoid having to constantly uninstall and install the application and still being quite close to how the final application will run.

How to set proxy for wget?

For all users of the system via the /etc/wgetrc or for the user only with the ~/.wgetrc file:


or via -e options placed after the URL:

wget ... -e use_proxy=yes -e http_proxy= ...

Git push rejected after feature branch rebase

I would do as below

rebase feature
git checkout -b feature2 origin/feature
git push -u origin feature2:feature2
Delete the old remote branch feature
git push -u origin feature:feature

Now the remote will have feature(rebased on latest master) and feature2(with old master head). This would allow you to compare later if you have done mistakes in reolving conflicts.

403 Forbidden error when making an ajax Post request in Django framework

Because you did not post the csrfmiddlewaretoken, so Django forbid you. this document can help you.

What is the difference between C and embedded C?

Basically, there isn't one. Embedded refers to the hosting computer / microcontroller, not the language. The embeddded system might have fewer resources and interfaces for the programmer to play with, and hence C will be used differently, but it is still the same ISO defined language.

What is difference between Errors and Exceptions?

Error is something that most of the time you cannot handle it.

Exception was meant to give you an opportunity to do something with it. like try something else or write to the log.

  //connect to database 1
catch(DatabaseConnctionException err){
  //connect to database 2
  //write the err to log

Hash Map in Python

It's built-in for Python. See dictionaries.

Based on your example:

streetno = {"1": "Sachine Tendulkar",
            "2": "Dravid",
            "3": "Sehwag",
            "4": "Laxman",
            "5": "Kohli" }

You could then access it like so:

sachine = streetno["1"]

Also worth mentioning: it can use any non-mutable data type as a key. That is, it can use a tuple, boolean, or string as a key.

Any way (or shortcut) to auto import the classes in IntelliJ IDEA like in Eclipse?

Use control+option+O to auto-import the package or auto remove unused packages on MacOS

How to get the last character of a string in a shell?

Every answer so far implies the word "shell" in the question equates to Bash.

This is how one could do that in a standard Bourne shell:

printf $str | tail -c 1

android get real path by Uri.getPath()

@Rene Juuse - above in comments... Thanks for this link !

. the code to get the real path is a bit different from one SDK to another so below we have three methods that deals with different SDKs.

getRealPathFromURI_API19(): returns real path for API 19 (or above but not tested) getRealPathFromURI_API11to18(): returns real path for API 11 to API 18 getRealPathFromURI_below11(): returns real path for API below 11

public class RealPathUtil {

public static String getRealPathFromURI_API19(Context context, Uri uri){
    String filePath = "";
    String wholeID = DocumentsContract.getDocumentId(uri);

     // Split at colon, use second item in the array
     String id = wholeID.split(":")[1];

     String[] column = { MediaStore.Images.Media.DATA };     

     // where id is equal to             
     String sel = MediaStore.Images.Media._ID + "=?";

     Cursor cursor = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, 
                               column, sel, new String[]{ id }, null);

     int columnIndex = cursor.getColumnIndex(column[0]);

     if (cursor.moveToFirst()) {
         filePath = cursor.getString(columnIndex);
     return filePath;

public static String getRealPathFromURI_API11to18(Context context, Uri contentUri) {
      String[] proj = { MediaStore.Images.Media.DATA };
      String result = null;

      CursorLoader cursorLoader = new CursorLoader(
        contentUri, proj, null, null, null);        
      Cursor cursor = cursorLoader.loadInBackground();

      if(cursor != null){
       int column_index = 
       result = cursor.getString(column_index);
      return result;  

public static String getRealPathFromURI_BelowAPI11(Context context, Uri contentUri){
           String[] proj = { MediaStore.Images.Media.DATA };
           Cursor cursor = context.getContentResolver().query(contentUri, proj, null, null, null);
           int column_index
      = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
           return cursor.getString(column_index);


UPDATE 2016 March

To fix all problems with path of images i try create a custom gallery as facebook and other apps. This is because you can use just local files ( real files, not virtual or temporary) , i solve all problems with this library. (this library is to take photo from camera or choose from galery , if you choose from gallery he have a drawer with albums and just show local files)

Where is the Postgresql config file: 'postgresql.conf' on Windows?

On my machine:

C:\Program Files (x86)\OpenERP 6.1-20121026-233219\PostgreSQL\data

How to cancel a Task in await?

One case which hasn't been covered is how to handle cancellation inside of an async method. Take for example a simple case where you need to upload some data to a service get it to calculate something and then return some results.

public async Task<Results> ProcessDataAsync(MyData data)
    var client = await GetClientAsync();
    await client.UploadDataAsync(data);
    await client.CalculateAsync();
    return await client.GetResultsAsync();

If you want to support cancellation then the easiest way would be to pass in a token and check if it has been cancelled between each async method call (or using ContinueWith). If they are very long running calls though you could be waiting a while to cancel. I created a little helper method to instead fail as soon as canceled.

public static class TaskExtensions
    public static async Task<T> WaitOrCancel<T>(this Task<T> task, CancellationToken token)
        await Task.WhenAny(task, token.WhenCanceled());

        return await task;

    public static Task WhenCanceled(this CancellationToken cancellationToken)
        var tcs = new TaskCompletionSource<bool>();
        cancellationToken.Register(s => ((TaskCompletionSource<bool>)s).SetResult(true), tcs);
        return tcs.Task;

So to use it then just add .WaitOrCancel(token) to any async call:

public async Task<Results> ProcessDataAsync(MyData data, CancellationToken token)
    Client client;
        client = await GetClientAsync().WaitOrCancel(token);
        await client.UploadDataAsync(data).WaitOrCancel(token);
        await client.CalculateAsync().WaitOrCancel(token);
        return await client.GetResultsAsync().WaitOrCancel(token);
    catch (OperationCanceledException)
        if (client != null)
            await client.CancelAsync();

Note that this will not stop the Task you were waiting for and it will continue running. You'll need to use a different mechanism to stop it, such as the CancelAsync call in the example, or better yet pass in the same CancellationToken to the Task so that it can handle the cancellation eventually. Trying to abort the thread isn't recommended.

Onclick CSS button effect

Push down the whole button. I suggest this it is looking nice in button.

#button:active {
    position: relative;
    top: 1px;

if you only want to push text increase top-padding and decrease bottom padding. You can also use line-height.

best OCR (Optical character recognition) example in android

Like you I also faced many problems implementing OCR in Android, but after much Googling I found the solution, and it surely is the best example of OCR.

Let me explain using step-by-step guidance.

First, download the source code from

Import all three projects. After importing you will get an error. To solve the error you have to create a res folder in the tess-two project

enter image description here

First, just create res folder in tess-two by tess-two->RightClick->new Folder->Name it "res"

After doing this in all three project the error should be gone.

Now download the source code from, here you will get best example.

Now you just need to import it into your workspace, but first you have to download android-ndk from this site: i have windows 7 - 32 bit PC so I have download this file

Now extract it suppose I have extract it into E:\Software\android-ndk-r9 so I will set this path on Environment Variable

Right Click on MyComputer->Property->Advance-System-Settings->Advance->Environment Variable-> find PATH on second below Box and set like path like below picture

enter image description here

done it

Now open cmd and go to on D:\Android Workspace\tess-two like below

enter image description here

If you have successfully set up environment variable of NDK then just type ndk-build just like above picture than enter you will not get any kind of error and all file will be compiled successfully:

Now download other source code also from , and extract and import it and give it name OCRTest, like in my PC which is in D:\Android Workspace\OCRTest

enter image description here

Import test-two in this and run OCRTest and run it; you will get the best example of OCR.

Get Android API level of phone currently running my application

try this :Float.valueOf(android.os.Build.VERSION.RELEASE) <= 2.1

How to get parameters from a URL string?

In Laravel, I'm use:

private function getValueFromString(string $string, string $key)
    parse_str(parse_url($string, PHP_URL_QUERY), $result);

    return isset($result[$key]) ? $result[$key] : null;

Find maximum value of a column and return the corresponding row values using Pandas


This will return the entire row with max value

How do you change the character encoding of a postgres database?

Dumping a database with a specific encoding and try to restore it on another database with a different encoding could result in data corruption. Data encoding must be set BEFORE any data is inserted into the database.

Check this : When copying any other database, the encoding and locale settings cannot be changed from those of the source database, because that might result in corrupt data.

And this : Some locale categories must have their values fixed when the database is created. You can use different settings for different databases, but once a database is created, you cannot change them for that database anymore. LC_COLLATE and LC_CTYPE are these categories. They affect the sort order of indexes, so they must be kept fixed, or indexes on text columns would become corrupt. (But you can alleviate this restriction using collations, as discussed in Section 22.2.) The default values for these categories are determined when initdb is run, and those values are used when new databases are created, unless specified otherwise in the CREATE DATABASE command.

I would rather rebuild everything from the begining properly with a correct local encoding on your debian OS as explained here :

su root

Reconfigure your local settings :

dpkg-reconfigure locales

Choose your locale (like for instance for french in Switzerland : fr_CH.UTF8)

Uninstall and clean properly postgresql :

apt-get --purge remove postgresql\*
rm -r /etc/postgresql/
rm -r /etc/postgresql-common/
rm -r /var/lib/postgresql/
userdel -r postgres
groupdel postgres

Re-install postgresql :

aptitude install postgresql-9.1 postgresql-contrib-9.1 postgresql-doc-9.1

Now any new database will be automatically be created with correct encoding, LC_TYPE (character classification), and LC_COLLATE (string sort order).

How to set up default schema name in JPA configuration?

I had to set the value in '' and ""

          default_schema: '"schema"'

How to sort an associative array by its values in Javascript?

@commonpike's answer is "the right one", but as he goes on to comment...

most browsers nowadays just support Object.keys()

Yeah.. Object.keys() is WAY better.

But what's even better? Duh, it's it in coffeescript!

sortedKeys = (x) -> Object.keys(x).sort (a,b) -> x[a] - x[b]

  'a' :  1
  'b' :  3
  'c' :  4
  'd' : -1

[ 'd', 'a', 'b', 'c' ]

PHP Fatal error: Cannot access empty property

I realise this answer is not a direct response to the problem described by the OP, but I found this question as a result of searching for the same error message. I thought it worth posting my experience here just in case anybody is muddling over the same thing...

You can encounter the error in question as a result of a poorly formatted for loop over an associative array. In a fit of bone-headedness, I was using -> instead of => in my for statement:

        foreach ($object->someArray as $key->$val) {
            // do something

Of course, I should have had:

        foreach ($object->someArray as $key=>$val) {
            // do something

I confused myself at first, thinking the reported error was referring to the someArray property!

Generating a random password in php

//define a function. It is only 3 lines!   
function generateRandomPassword($length = 5){
    $chars = "0123456789bcdfghjkmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ";
    return substr(str_shuffle($chars),0,$length);

echo generateRandomPassword(5); //random password legth: 5
echo generateRandomPassword(6); //random password legth: 6
echo generateRandomPassword(7); //random password legth: 7

ITextSharp insert text to an existing pdf

I found a way to do it (dont know if it is the best but it works)

string oldFile = "oldFile.pdf";
string newFile = "newFile.pdf";

// open the reader
PdfReader reader = new PdfReader(oldFile);
Rectangle size = reader.GetPageSizeWithRotation(1);
Document document = new Document(size);

// open the writer
FileStream fs = new FileStream(newFile, FileMode.Create, FileAccess.Write);
PdfWriter writer = PdfWriter.GetInstance(document, fs);

// the pdf content
PdfContentByte cb = writer.DirectContent;

// select the font properties
BaseFont bf = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.CP1252,BaseFont.NOT_EMBEDDED);
cb.SetFontAndSize(bf, 8);

// write the text in the pdf content
string text = "Some random blablablabla...";
// put the alignment and coordinates here
cb.ShowTextAligned(1, text, 520, 640, 0);
text = "Other random blabla...";
// put the alignment and coordinates here
cb.ShowTextAligned(2, text, 100, 200, 0);

// create the new page and add it to the pdf
PdfImportedPage page = writer.GetImportedPage(reader, 1);
cb.AddTemplate(page, 0, 0);

// close the streams and voilá the file should be changed :)

I hope this can be usefull for someone =) (and post here any errors)


Expanding on Aristotle’s answer you can SELECT from a dummy 'singleton' table (a table of your own creation with a single row). This avoids some duplication.

I've also kept the example portable across MySQL and SQLite and used a 'date_added' column as an example of how you could set a column only the first time.

   "About this site",
 FROM singleton
 LEFT JOIN page AS old ON = "about";

How to find tags with only certain attributes - BeautifulSoup

if you want to only search with attribute name with any value

from bs4 import BeautifulSoup
import re

soup= BeautifulSoup(html.text,'lxml')
results = soup.findAll("td", {"valign" : re.compile(r".*")})

as per Steve Lorimer better to pass True instead of regex

results = soup.findAll("td", {"valign" : True})

What's the fastest way to loop through an array in JavaScript?

Try this:

var myarray =[],
i = myarray.lenght;
// do somthing

Good PHP ORM Library?

Doctrine is probably your best bet. Prior to Doctrine, DB_DataObject was essentially the only other utility that was open sourced.

How do I force a vertical scrollbar to appear?

html { overflow-y: scroll; }

This css rule causes a vertical scrollbar to always appear.


How to properly compare two Integers in Java?

this method compares two Integer with null check, see tests

public static boolean compare(Integer int1, Integer int2) {
    if(int1!=null) {
        return int1.equals(int2);
    } else {
        return int2==null;
    //inline version:
    //return (int1!=null) ? int1.equals(int2) : int2==null;

System.out.println(compare(1,1));           //true
System.out.println(compare(0,1));           //false
System.out.println(compare(1,0));           //false
System.out.println(compare(null,0));        //false
System.out.println(compare(0,null));        //false
System.out.println(compare(null,null));     //true

Truncate all tables in a MySQL database in one command?

I know this isn't exactly one command, but the desired result can be achieved from within phpMyAdmin by following these steps:

  1. Select (all) tables to be removed (Check All)
  2. Select "Drop" / "Truncate" from the "With selected:" list
  3. On the confirmation page ("Do you really want to:") copy the query (everything with the red background)
  4. Go at the top and click on SQL and write: "SET FOREIGN_KEY_CHECKS=0;" then paste the previously copied query
  5. Click "Go"

The idea is to quickly get all the tables from the database (which you do in 5 seconds and 2 clicks) but disable foreign key checks first. No CLI and no dropping the database and adding it again.

Could not read JSON: Can not deserialize instance of hello.Country[] out of START_OBJECT token

Another solution:

public class CountryInfoResponse {
  private List<Object> geonames;

Usage of a generic Object-List solved my problem, as there were other Datatypes like Boolean too.

When do you use Git rebase instead of Git merge?

This sentence gets it:

In general, the way to get the best of both worlds is to rebase local changes you’ve made, but haven’t shared yet, before you push them in order to clean up your story, but never rebase anything you’ve pushed somewhere.

Source: 3.6 Git Branching - Rebasing, Rebase vs. Merge

Use 'import module' or 'from module import'?

Import Module - You don't need additional efforts to fetch another thing from module. It has disadvantages such as redundant typing

Module Import From - Less typing &More control over which items of a module can be accessed.To use a new item from the module you have to update your import statement.

How do I extract specific 'n' bits of a 32-bit unsigned integer in C?

Instead of thinking of it as 'extracting', I like to think of it as 'isolating'. Once the desired bits are isolated, you can do what you will with them.

To isolate any set of bits, apply an AND mask.

If you want the last X bits of a value, there is a simple trick that can be used.

unsigned  mask;
mask = (1 << X) - 1;
lastXbits = value & mask;

If you want to isolate a run of X bits in the middle of 'value' starting at 'startBit' ...

unsigned  mask;
mask = ((1 << X) - 1) << startBit;
isolatedXbits = value & mask;

Hope this helps.

Switch to another Git tag

As of Git v2.23.0 (August 2019), git switch is preferred over git checkout when you’re simply switching branches/tags. I’m guessing they did this since git checkout had two functions: for switching branches and for restoring files. So in v2.23.0, they added two new commands, git switch, and git restore, to separate those concerns. I would predict at some point in the future, git checkout will be deprecated.

To switch to a normal branch, use git switch <branch-name>. To switch to a commit-like object, including single commits and tags, use git switch --detach <commitish>, where <commitish> is the tag name or commit number.

The --detach option forces you to recognize that you’re in a mode of “inspection and discardable experiments”. To create a new branch from the commitish you’re switching to, use git switch -c <new-branch> <start-point>.

Warning: #1265 Data truncated for column 'pdd' at row 1

As the message error says, you need to Increase the length of your column to fit the length of the data you are trying to insert (0000-00-00)


Following your comment, I run a test table:

mysql> create table testDate(id int(2) not null auto_increment, pdd date default null, primary key(id));
Query OK, 0 rows affected (0.20 sec)


mysql> insert into testDate values(1,'0000-00-00');
Query OK, 1 row affected (0.06 sec)


So, aparently you want to insert a NULL value to pdd field as your comment states ? You can do that in 2 ways like this:

Method 1:

mysql> insert into testDate values(2,'');
Query OK, 1 row affected, 1 warning (0.06 sec)

Method 2:

mysql> insert into testDate values(3,NULL);
Query OK, 1 row affected (0.07 sec)


You failed to change the default value of pdd field. Here is the syntax how to do it (in my case, I set it to NULL in the start, now I will change it to NOT NULL)

mysql> alter table testDate modify pdd date not null;
Query OK, 3 rows affected, 1 warning (0.60 sec)
Records: 3  Duplicates: 0  Warnings: 1

How do you set the EditText keyboard to only consist of numbers on Android?

Place the below lines in your <EditText>:


How to use GROUP BY to concatenate strings in SQL Server?

This kind of question is asked here very often, and the solution is going to depend a lot on the underlying requirements:


Typically, there is no SQL-only way to do this without either dynamic sql, a user-defined function, or a cursor.

Anaconda site-packages

At least with Miniconda (I assume it's the same for Anaconda), within the environment folder, the packages are installed in a folder called \conda-meta.



If you install on the base environment, the location is:


How to use a App.config file in WPF applications?

In your app.config, change your appsetting to:

        <setting name="appsetting" serializeAs="String">

Then, in the code-behind:

string xmlDataDirectory = WpfApplication1.Properties.Settings.Default.appsetting.ToString()

Where does Java's String constant pool live, the heap or the stack?

As explained by this answer, the exact location of the string pool is not specified and can vary from one JVM implementation to another.

It is interesting to note that until Java 7, the pool was in the permgen space of the heap on hotspot JVM but it has been moved to the main part of the heap since Java 7:

Area: HotSpot
Synopsis: In JDK 7, interned strings are no longer allocated in the permanent generation of the Java heap, but are instead allocated in the main part of the Java heap (known as the young and old generations), along with the other objects created by the application. This change will result in more data residing in the main Java heap, and less data in the permanent generation, and thus may require heap sizes to be adjusted. Most applications will see only relatively small differences in heap usage due to this change, but larger applications that load many classes or make heavy use of the String.intern() method will see more significant differences. RFE: 6962931

And in Java 8 Hotspot, Permanent Generation has been completely removed.

scroll image with continuous scrolling using marquee tag

I think you set the marquee width related to 5 images total width. It works fine

ex: <marquee style="width:700px"></marquee>

Encode html entities in javascript

You can use the charCodeAt() method to check if the specified character has a value higher than 127 and convert it to a numeric character reference using toString(16).

SQLAlchemy: What's the difference between flush() and commit()?

commit () records these changes in the database. flush () is always called as part of the commit () (1) call. When you use a Session object to query a database, the query returns results from both the database and the reddened parts of the unrecorded transaction it is performing.

Remove .php extension with .htaccess

I found 100% working Concept for me:

# Options is required by Many Hosting
Options +MultiViews

RewriteEngine on

# For .php & .html URL's:
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([^\.]+)$ $1.php [NC,L]
RewriteRule ^([^\.]+)$ $1.html [NC,L]

Use this code in Root of your website .htaccess file like :

offline - wamp\www\YourWebDir

online - public_html/

If it doesn't work correct, then change the settings of your Wamp Server: 1) Left click WAMP icon 2) Apache 3) Apache Modules 4) Left click rewrite_module

Creating a textarea with auto-resize

The best solution (works and is short) for me is:

    $(document).on('input', 'textarea', function () {
        $(this).outerHeight(38).outerHeight(this.scrollHeight); // 38 or '1em' -min-height

It works like a charm without any blinking with paste (with mouse also), cut, entering and it shrinks to the right size.

Please take a look at jsFiddle.

How to dynamically remove items from ListView on a button click?


or you can call again


PHP XML Extension: Not installed

Had the same problem running PHP 7.2. I had to do the following :

sudo apt-get install php7.2-xml

Set a button group's width to 100% and make buttons equal width?

BOOTSTRAP 2 (source)

The problem is that there is no width set on the buttons. Try this:

.btn {width:20%;}


By default the buttons take an auto width of its text length plus some padding, so I guess for your example it is probably more like 14.5% for 5 buttons (to compensate for the padding).


If you don't want to try and compensate for padding you can use box-sizing:border-box;

How to convert a Map to List in Java?

// you can use this
List<Value> list = new ArrayList<Value>(map.values());

// or you may use 
List<Value> list = new ArrayList<Value>();
for (Map.Entry<String, String> entry : map.entrySet())

JPanel setBackground(Color.BLACK) does nothing

I just tried a bare-bones implementation and it just works:

public class Test {

    public static void main(String[] args) {
            JFrame frame = new JFrame("Hello");
            frame.setPreferredSize(new Dimension(200, 200));
            frame.add(new Board());

public class Board extends JPanel {

    private Player player = new Player();

    public Board(){

    public void paintComponent(Graphics g){  
        g.fillOval(player.getCenter().x, player.getCenter().y,
             player.getRadius(), player.getRadius());

public class Player {

    private Point center = new Point(50, 50);

    public Point getCenter() {
        return center;

    private int radius = 10;

    public int getRadius() {
        return radius;

How do I get list of all tables in a database using TSQL?

--for oracle
select tablespace_name, table_name from all_tables;

This link can provide much more information on this topic

How to set index.html as root file in Nginx?

According to the documentation Checks the existence of files in the specified order and uses the first found file for request processing; the processing is performed in the current context. The path to a file is constructed from the file parameter according to the root and alias directives. It is possible to check directory’s existence by specifying a slash at the end of a name, e.g. “$uri/”. If none of the files were found, an internal redirect to the uri specified in the last parameter is made. Important

an internal redirect to the uri specified in the last parameter is made.

So in last parameter you should add your page or code if first two parameters returns false.

location / {
  try_files $uri $uri/index.html index.html;

How to combine 2 plots (ggplot) into one plot?

Dummy data (you should supply this for us)

visual1 = data.frame(ISSUE_DATE=runif(100,2006,2008),COUNTED=runif(100,0,50))
visual2 = data.frame(ISSUE_DATE=runif(100,2006,2008),COUNTED=runif(100,0,50))


visuals = rbind(visual1,visual2)
visuals$vis=c(rep("visual1",100),rep("visual2",100)) # 100 points of each flavour

Now do:

 ggplot(visuals, aes(ISSUE_DATE,COUNTED,group=vis,col=vis)) + 
   geom_point() + geom_smooth()

and adjust colours etc to taste.

enter image description here

Where does gcc look for C and C++ header files?

You can create a file that attempts to include a bogus system header. If you run gcc in verbose mode on such a source, it will list all the system include locations as it looks for the bogus header.

$ echo "#include <bogus.h>" > t.c; gcc -v t.c; rm t.c


#include "..." search starts here:
#include <...> search starts here:
 /System/Library/Frameworks (framework directory)
 /Library/Frameworks (framework directory)
End of search list.


t.c:1:32: error: bogus.h: No such file or directory

What is the difference between dynamic programming and greedy approach?

the major difference between greedy method and dynamic programming is in greedy method only one optimal decision sequence is ever generated and in dynamic programming more than one optimal decision sequence may be generated.

Google Maps API v3: InfoWindow not sizing correctly

You should give the content to InfoWindow from jQuery object.

var $infoWindowContent = $("<div class='infowin-content'>Content goes here</div>");
var infoWindow = new google.maps.InfoWindow();

Open source face recognition for Android

macgyver offers face detection programs via a simple to use API.

The program below takes a reference to a public image and will return an array of the coordinates and dimensions of any faces detected in the image.

Twitter Bootstrap Multilevel Dropdown Menu

I was able to fix the sub-menu's always pinning to the top of the parent menu from Andres's answer with the following addition:

.dropdown-menu li {
    position: relative;

I also add an icon "icon-chevron-right" on items which contain menu sub-menus, and change the icon from black to white on hover (to compliment the text changing to white and look better with the selected blue background).

Here is the full less/css change (replace the above with this):

.dropdown-menu li {
    position: relative;

    [class^="icon-"] {
        float: right;

    &:hover {
        // Switch to white icons on hover
        [class^="icon-"] {
            background-image: url("../img/glyphicons-halflings-white.png");

PHPMyAdmin Default login password

Default is:

Username: root

Password: [null]

The Password is set to 'password' in some versions.

Reflection generic get field value

 Integer typeValue = 0;
 try {
     Class<Types> types = Types.class;
     java.lang.reflect.Field field = types.getDeclaredField("Type");
     Object value = field.get(types);
     typeValue = (Integer) value;
 } catch (Exception e) {

Extract time from moment js object

You can do something like this

var now = moment();
var time = now.hour() + ':' + now.minutes() + ':' + now.seconds();
time = time + ((now.hour()) >= 12 ? ' PM' : ' AM');

Enable & Disable a Div and its elements in Javascript

If you want to disable all the div's controls, you can try adding a transparent div on the div to disable, you gonna make it unclickable, also use fadeTo to create a disable appearance.

try this.

$('#DisableDiv').append('<div style="position: absolute;top:0;left:0;width: 100%;height:100%;z-index:2;opacity:0.4;filter: alpha(opacity = 50)"></div>');

Print JSON parsed object?

Most debugger consoles support displaying objects directly. Just use


Depending on your debugger this most likely will display the object in the console as a collapsed tree. You can open the tree and inspect the object.

Split bash string by newline characters

There is another way if all you want is the text up to the first line feed:



After that y will contain some and nothing else (no line feed).

What is happening here?

We perform a parameter expansion substring removal (${PARAMETER%PATTERN}) for the shortest match up to the first ANSI C line feed ($'\n') and drop everything that follows (*).

How can I pass a member function where a free function is expected?

Since 2011, if you can change function1, do so, like this:

#include <functional>
#include <cstdio>

using namespace std;

class aClass
    void aTest(int a, int b)
        printf("%d + %d = %d", a, b, a + b);

template <typename Callable>
void function1(Callable f)
    f(1, 1);

void test(int a,int b)
    printf("%d - %d = %d", a , b , a - b);

int main()
    aClass obj;

    // Free function

    // Bound member function
    using namespace std::placeholders;
    function1(std::bind(&aClass::aTest, obj, _1, _2));

    // Lambda
    function1([&](int a, int b) {
        obj.aTest(a, b);

(live demo)

Notice also that I fixed your broken object definition (aClass a(); declares a function).

sql primary key and index

Declaring a PRIMARY KEY or UNIQUE constraint causes SQL Server to automatically create an index.

An unique index can be created without matching a constraint, but a constraint (either primary key or unique) cannot exist without having a unique index.

From here, the creation of a constraint will:

  • cause an index with the same name to be created
  • deny dropping the created index as constraint is not allowed to exists without it

and at the same time dropping the constraint will drop the associated index.

So, is there actual difference between a PRIMARY KEY or UNIQUE INDEX:

  • NULL values are not allowed in PRIMARY KEY, but allowed in UNIQUE index; and like in set operators (UNION, EXCEPT, INTERSECT), here NULL = NULL which means that you can have only one value as two NULLs are find as duplicates of each other;
  • only one PRIMARY KEY may exists per table while 999 unique indexes can be created
  • when PRIMARY KEY constraint is created, it is created as clustered unless there is already a clustered index on the table or NONCLUSTERED is used in its definition; when UNIQUE index is created, it is created as NONCLUSTERED unless it is not specific to be CLUSTERED and such already does not exist;

How to use cookies in Python Requests

Summary (@Freek Wiekmeijer, @gtalarico) other's answer:

Logic of Login

  • Many resource(pages, api) need authentication, then can access, otherwise 405 Not Allowed
  • Common authentication=grant access method are:
    • cookie
    • auth header
      • Basic xxx
      • Authorization xxx

How use cookie in requests to auth

  1. first get/generate cookie
  2. send cookie for following request
  • manual set cookie in headers
  • auto process cookie by requests's
    • session to auto manage cookies
    • response.cookies to manually set cookies

use requests's session auto manage cookies

curSession = requests.Session() 
# all cookies received will be stored in the session object

payload={'username': "yourName",'password': "yourPassword"}, data=payload)
# internally return your expected cookies, can use for following auth

# internally use previously generated cookies, can access the resources


manually control requests's response.cookies

payload={'username': "yourName",'password': "yourPassword"}
resp1 =, data=payload)

# manually pass previously returned cookies into following request
resp2 = requests.get(secondUrl, cookies= resp1.cookies)

resp3 = requests.get(thirdUrl, cookies= resp2.cookies)

How to convert a NumPy array to PIL image applying matplotlib colormap

The method described in the accepted answer didn't work for me even after applying changes mentioned in its comments. But the below simple code worked:

import matplotlib.pyplot as plt
plt.imsave(filename, np_array, cmap='Greys')

np_array could be either a 2D array with values from 0..1 floats o2 0..255 uint8, and in that case it needs cmap. For 3D arrays, cmap will be ignored.

How to see top processes sorted by actual memory usage?

you can specify which column to sort by, with following steps:

* top
* shift + F
* select a column from the list
    e.g. n means sort by memory,
* press enter
* ok

Exporting the values in List to excel

Using the CSV idea, if it's just a list of Strings. Assuming l is your list:

using System.IO;

using(StreamWriter sw = File.CreateText("list.csv"))
  for(int i = 0; i < l.Count; i++)

Check if a string contains an element from a list (of strings)

There were a number of suggestions from an earlier similar question "Best way to test for existing string against a large list of comparables".

Regex might be sufficient for your requirement. The expression would be a concatenation of all the candidate substrings, with an OR "|" operator between them. Of course, you'll have to watch out for unescaped characters when building the expression, or a failure to compile it because of complexity or size limitations.

Another way to do this would be to construct a trie data structure to represent all the candidate substrings (this may somewhat duplicate what the regex matcher is doing). As you step through each character in the test string, you would create a new pointer to the root of the trie, and advance existing pointers to the appropriate child (if any). You get a match when any pointer reaches a leaf.

How to get the current directory of the cmdlet being executed

I had similar problems and it made me a lot of trouble since I am making programs written in PowerShell (full end user GUI applications) and I have a lot of files and resources I need to load from disk. From my experience, using . to represent current directory is unreliable. It should represent current working directory, but it often does not. It appears that PowerShell saves location from which PowerShell has been invoked inside .. To be more precise, when PowerShell is first started, it starts, by default, inside your home user directory. That is usually directory of your user account, something like C:\USERS\YOUR USER NAME. After that, PowerShell changes directory to either directory from which you invoked it, or to directory where script you are executing is located before either presenting you with PowerShell prompt or running the script. But that happens after PowerShell app itself originally starts inside your home user directory.

And . represents that initial directory inside which PowerShell started. So . only represents current directory in case if you invoked PowerShell from the wanted directory. If you later change directory in PowerShell code, change appears not to be reflected inside . in every case. In some cases . represents current working directory, and in others directory from which PowerShell (itself, not the script) has been invoked, what can lead to inconsistent results. For this reason I use invoker script. PowerShell script with single command inside: POWERSHELL. That will ensure that PowerShell is invoked from the wanted directory and thus make . represent current directory. But it only works if you do not change directory later in PowerShell code. In case of a script, I use invoker script which is similar to last one I mentioned, except it contains a file option: POWERSHELL -FILE DRIVE:\PATH\SCRIPT NAME.PS1. That ensures that PowerShell is started inside current working directory.

Simply clicking on script invokes PowerShell from your home user directory no matter where script is located. It results with current working directory being directory where script is located, but PowerShell invocation directory being C:\USERS\YOUR USER NAME, and with . returning one of these two directories depending on the situation, what is ridiculous.

But to avoid all this fuss and using invoker script, you can simply use either $PWD or $PSSCRIPTROOT instead of . to represent current directory depending on weather you wish to represent current working directory or directory from which script has been invoked. And if you, for some reason, want to retrieve other of two directories which . returns, you can use $HOME.

I personally just have invoker script inside root directory of my apps I develop with PowerShell which invokes my main app script, and simply remember to never ever change current working directory inside my source code of my app, so I never have to worry about this, and I can use . to represent current directory and to support relative file addressing in my applications without any problems. This should work in newer versions of PowerShell (newer than version 2).

Git: Permission denied (publickey) fatal - Could not read from remote repository. while cloning Git repository

After changing permissions of folder in which I was cloning, it worked:

sudo chown -R ubuntu:ubuntu /var/projects

Check if a temporary table exists and delete if it exists before creating a temporary table

The statement should be of the order

  1. Alter statement for the table
  2. GO
  3. Select statement.

Without 'GO' in between, the whole thing will be considered as one single script and when the select statement looks for the column,it won't be found.

With 'GO' , it will consider the part of the script up to 'GO' as one single batch and will execute before getting into the query after 'GO'.

Private Variables and Methods in Python

Please note that there is no such thing as "private method" in Python. Double underscore is just name mangling:

>>> class A(object):
...     def __foo(self):
...         pass
>>> a = A()
>>> A.__dict__.keys()
['__dict__', '_A__foo', '__module__', '__weakref__', '__doc__']
>>> a._A__foo()

So therefore __ prefix is useful when you need the mangling to occur, for example to not clash with names up or below inheritance chain. For other uses, single underscore would be better, IMHO.

EDIT, regarding confusion on __, PEP-8 is quite clear on that:

If your class is intended to be subclassed, and you have attributes that you do not want subclasses to use, consider naming them with double leading underscores and no trailing underscores. This invokes Python's name mangling algorithm, where the name of the class is mangled into the attribute name. This helps avoid attribute name collisions should subclasses inadvertently contain attributes with the same name.

Note 3: Not everyone likes name mangling. Try to balance the need to avoid accidental name clashes with potential use by advanced callers.

So if you don't expect subclass to accidentally re-define own method with same name, don't use it.

Using Cookie in Asp.Net Mvc 4


This line of code doesn't do anything. It is the equivalent of:

DateTime temp = userCookie.Expires.AddDays(365); 
//do nothing with temp

You probably want

userCookie.Expires = DateTime.Now.AddDays(365); 

Issue with adding common code as git submodule: "already exists in the index"

You need to remove your submodule git repository (projectfolder in this case) first for git path.

rm -rf projectfolder

git rm -r projectfolder

and then add submodule

git submodule add <git_submodule_repository> projectfolder

Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve

Today I have the similar problem.

Previous in my project gradle

// Top-level build file where you can add configuration options common to all 
allprojects {
repositories {
    maven { url "" }
    maven { url ''}

Then I just added this below line in allprojects

maven {
        url ""

It saved my day.

And now my current allproject {} code looks like this

allprojects {
repositories {
    maven { url "" }
    maven { url ''}
    maven {
        url ""

Rails has_many with alias name

If you use has_many through, and want to alias:

has_many :alias_name, through: model_name, source: initial_name

Purpose of ESI & EDI registers?

In addition to the string operations (MOVS/INS/STOS/CMPS/SCASB/W/D/Q etc.) mentioned in the other answers, I wanted to add that there are also more "modern" x86 assembly instructions that implicitly use at least EDI/RDI:

The SSE2 MASKMOVDQU (and the upcoming AVX VMASKMOVDQU) instruction selectively write bytes from an XMM register to memory pointed to by EDI/RDI.

How to check if android checkbox is checked within its onClick method (declared in XML)?

You can try this code:

public void itemClicked(View v) {
 //code to check if this checkbox is checked!
   // code inside if

Set Radiobuttonlist Selected from Codebehind

Try this option:

radio1.Items.FindByValue("1").Selected = true;

PHP output showing little black diamonds with a question mark

Using the same charset (as suggested here) in both the database and the HTML has not worked for me... So remembering that the code is generated as HTML, I chose to use the &quot;(HTML code) or the &#34; (ISO Latin-1 code) in my database text where quotes were used. This solved the problem while providing me a quotation mark. It is odd to note that prior to this solution, only some of the quotation marks and apostrophes did not display correctly while others did, however, the special code did work in all instances.

Node.js Mongoose.js string to ObjectId function

Judging from the comments, you are looking for:




How can I use a JavaScript variable as a PHP variable?

You seem to be confusing client-side and server side code. When the button is clicked you need to send (post, get) the variables to the server where the php can be executed. You can either submit the page or use an ajax call to submit just the data. -don

How can I pass request headers with jQuery's getJSON() method?

The $.getJSON() method is shorthand that does not let you specify advanced options like that. To do that, you need to use the full $.ajax() method.

Notice in the documentation at

This is a shorthand Ajax function, which is equivalent to:

  url: url,
  dataType: 'json',
  data: data,
  success: callback

So just use $.ajax() and provide all the extra parameters you need.

PHP DateTime __construct() Failed to parse time string (xxxxxxxx) at position x

You should use setTimestamp instead, if you hardcode it:

$start_date = new DateTime();

in your case

$start_date = new DateTime();

iOS 7 status bar back to iOS 6 default style in iPhone app?

Here another approach for projects that make extensive use of the Storyboard:


Goal of this approach is to recreate the same status bar style in iOS7 as there was in iOS6 (see question title "iOS 7 Status Bar Back to iOS 6 style?").


To achieve this we use the Storyboard as much as possible by shifting UI elements that are overlapped by the status bar (under iOS 7) downwards, whilst using deltas to revert the downwards layout change for iOS 6.1 or earlier. The resulting extra space in iOS 7 is then occupied by a UIView with the backgroundColor set to a color of our choosing. The latter can be created in code or using the Storyboard (see ALTERNATIVES below)


To get the desired result when following the steps below, it is assumed that View controller-based status bar appearance is set to NO and that your Status bar style is either set to "Transparent black style (alpha of 0.5)" or "Opaque black style". Both settings can be found/or added under "Info" in your project settings.


  • Add a subview to the UIWindow to serve as your status bar background. To achieve this, add the following to your AppDelegate's application: didFinishLaunchingWithOptions: after makeKeyAndVisible

    if (NSFoundationVersionNumber > NSFoundationVersionNumber_iOS_6_1) {
        UIView *statusBarBackgroundView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, yourAppsUIWindow.frame.size.width, 20)];
        statusBarBackgroundView.backgroundColor = [UIColor blackColor];
        [yourAppsUIWindow addSubview:statusBarBackgroundView];
  • Since you programmatically added a background for iOS 7 ONLY, you will have to adjust the layout of your UI elements that are overlapped by the status bar accordingly whilst preserving their layout for iOS6. To achieve this, do the following:

    • Ensure that Use Autolayout is unchecked for your Storyboard (this is because otherwise "iOS 6/7 Deltas" is not shown in the Size Inspector). To do this:
      • select your Storyboard file
      • show Utilities
      • select "Show the File Inspector"
      • Under "Interface Builder Document" uncheck "Use Autolayout"
    • Optionally, to help you monitor the layout changes for both iOS 7 AND 6 as you apply them, select the "Assistant Editor", select "Preview" and "iOS 6.1 or earlier": enter image description here enter image description here
    • Now select the UI element you want to adjust so it isn't overlapped by the status bar anymore
    • Select "Show the Size Inspector" in the Utilities column
    • Reposition your UI element along the Y-axis by the same amount as the statusbar bg height: enter image description here
    • And change the iOS6/7 Deltas value for Y by the same NEGATIVE amount as the statusbar bg height (Note the change in the iOS 6 preview if you're using it): enter image description here


To add even less code in storyboard-heavy projects and to have the statusbar background autorotate, instead of programmatically adding a background for your statusbar, you could add a colored view to each view controller that sits at the very top of said viewcontroller's main view. You would then change the height delta of this new view to the same negative amount as your view's height (to make it disappear under iOS 6).

The downside of this alternative (although maybe negligible considering the autorotate compatibility) is the fact that this extra view is not immediately visible if you are viewing your Storyboard for iOS 6. You would only know that it's there if you had a look at the "Document Outline" of the Storyboard.

How do you use subprocess.check_output() in Python?

The right answer (using Python 2.7 and later, since check_output() was introduced then) is:

py2output = subprocess.check_output(['python','','-i', 'test.txt'])

To demonstrate, here are my two programs:

import sys
print sys.argv

import subprocess
py2output = subprocess.check_output(['python', '', '-i', 'test.txt'])
print('py2 said:', py2output)

Running it:

$ python3
py2 said: b"['', '-i', 'test.txt']\n"

Here's what's wrong with each of your versions:

py2output = subprocess.check_output([str('python '),'-i', 'test.txt'])

First, str('python') is exactly the same thing as 'python'—you're taking a str, and calling str to convert it to an str. This makes the code harder to read, longer, and even slower, without adding any benefit.

More seriously, python can't be a single argument, unless you're actually trying to run a program named, say, /usr/bin/python\ Which you're not; you're trying to run, say, /usr/bin/python with first argument So, you need to make them separate elements in the list.

Your second version fixes that, but you're missing the ' before test.txt'. This should give you a SyntaxError, probably saying EOL while scanning string literal.

Meanwhile, I'm not sure how you found documentation but couldn't find any examples with arguments. The very first example is:

>>> subprocess.check_output(["echo", "Hello World!"])
b'Hello World!\n'

That calls the "echo" command with an additional argument, "Hello World!".


-i is a positional argument for argparse, test.txt is what the -i is

I'm pretty sure -i is not a positional argument, but an optional argument. Otherwise, the second half of the sentence makes no sense.

How to find the mime type of a file in python?

@toivotuo 's method worked best and most reliably for me under python3. My goal was to identify gzipped files which do not have a reliable .gz extension. I installed python3-magic.

import magic

filename = "./datasets/test"

def file_mime_type(filename):
    m =


for a gzipped file it returns: application/gzip; charset=binary

for an unzipped txt file (iostat data): text/plain; charset=us-ascii

for a tar file: application/x-tar; charset=binary

for a bz2 file: application/x-bzip2; charset=binary

and last but not least for me a .zip file: application/zip; charset=binary

Reliable way to convert a file to a byte[]

Others have noted that you can use the built-in File.ReadAllBytes. The built-in method is fine, but it's worth noting that the code you post above is fragile for two reasons:

  1. Stream is IDisposable - you should place the FileStream fs = new FileStream(filename, FileMode.Open,FileAccess.Read) initialization in a using clause to ensure the file is closed. Failure to do this may mean that the stream remains open if a failure occurs, which will mean the file remains locked - and that can cause other problems later on.
  2. fs.Read may read fewer bytes than you request. In general, the .Read method of a Stream instance will read at least one byte, but not necessarily all bytes you ask for. You'll need to write a loop that retries reading until all bytes are read. This page explains this in more detail.