Programs & Examples On 1.0

The 1.0 version of the .NET Framework. Use for questions specifically related to .NET Framework 1.0. For questions on .NET Framework generally, use the .net tag.

Get folder name of the file in Python

You are looking to use dirname. If you only want that one directory, you can use os.path.basename,

When put all together it looks like this:


That should get you "other_sub_dir"

The following is not the ideal approach, but I originally proposed,using os.path.split, and simply get the last item. which would look like this:


How would I find the second largest salary from the employee table?

select max(Salary) from Employee 
where Salary
  not in (Select top4 salary from Employee);

because answer is as follows


so 5th highest record will be displayed, first four will not be considered

CodeIgniter - Correct way to link to another page in a view

Best and easiest way is to use anchor tag in CodeIgniter like eg.

    echo anchor('name_of_controller_file/function_name_if_any', 'Sign Out', array('class' => '', 'id' => '')); 

Refer for details

This will surely work.

Toggle visibility property of div

Using jQuery:

  if ( $('#video-over').css('visibility') == 'hidden' )

On Windows, running "import tensorflow" generates No module named "_pywrap_tensorflow" error

For tensorflow with CPU only:

I had installed tensorflow using command:

pip3 install --upgrade tensorflow

This installed tensorflow 1.7
But could not import the tensorflow from withing python 3.6.5 amd64 using:

import tensorflow as tf

So, i downgraded the tensorflow version from 1.7 to 1.5 using following command:

pip3 install tensorflow==1.5

This uninstalled the previous version and installed 1.5. Now it works.

Seems that, my CPU does not support AVX instruction set that is needed in tensorflow 1.7

I had MSVCP140.DLL in the system folders and .DLL in the PATHEXT variable in Environment Variable.

How do you define a class of constants in Java?

Just use final class.

If you want to be able to add other values use an abstract class.

It doesn't make much sense using an interface, an interface is supposed to specify a contract. You just want to declare some constant values.

Use a URL to link to a Google map with a marker on it

If working with Basic4Android and looking for an easy fix to the problem, try this it works both Google maps and Openstreet even though OSM creates a bit of a messy result and thanx to [yndolok] for the google marker


GooglemRute=""&[FrmLatt]&","&[FrmLong]&"/"&[ToLatt]&","&[FrmLong]&"/@"&[ScreenX]&","&[ScreenY]&",14z/data=!3m1!4b1!4m2!4m1!3e0?hl=en"  'route ?hl=en



How to find the operating system version using JavaScript?

JavaScript have access to the window.navigator.platform - a string representing the platform of the browser:

Use it to extract whatever details you need (and can). Note that there are no guarantees that the client actually uses that platform since this can easily be modified in many ways.

jQuery toggle CSS?

You can do by maintaining the state as below:

    if($(this).attr('data-click-state') == 1) {
        $(this).attr('data-click-state', 0);
        $(this).css('background-color', 'red')
    else {
      $(this).attr('data-click-state', 1);
      $(this).css('background-color', 'orange')

Take a reference from hear codepen example

Best way to check for "empty or null value"

A lot of the answers are the shortest way, not the necessarily the best way if the column has lots of nulls. Breaking the checks up allows the optimizer to evaluate the check faster as it doesn't have to do work on the other condition.

(stringexpression IS NOT NULL AND trim(stringexpression) != '')

The string comparison doesn't need to be evaluated since the first condition is false.

Getting All Variables In Scope

I made a fiddle implementing (essentially) above ideas outlined by iman. Here is how it looks when you mouse over the second ipsum in return ipsum*ipsum - ...

enter image description here

The variables which are in scope are highlighted where they are declared (with different colors for different scopes). The lorem with red border is a shadowed variable (not in scope, but be in scope if the other lorem further down the tree wouldn't be there.)

I'm using esprima library to parse the JavaScript, and estraverse, escodegen, escope (utility libraries on top of esprima.) The 'heavy lifting' is done all by those libraries (the most complex being esprima itself, of course.)

How it works

ast = esprima.parse(sourceString, {range: true, sourceType: 'script'});

makes the abstract syntax tree. Then,

analysis = escope.analyze(ast);

generates a complex data structure encapsulating information about all the scopes in the program. The rest is gathering together the information encoded in that analysis object (and the abstract syntax tree itself), and making an interactive coloring scheme out of it.

So the correct answer is actually not "no", but "yes, but". The "but" being a big one: you basically have to rewrite significant parts of the chrome browser (and it's devtools) in JavaScript. JavaScript is a Turing complete language, so of course that is possible, in principle. What is impossible is doing the whole thing without using the entirety of your source code (as a string) and then doing highly complex stuff with that.

How to add a default "Select" option to this ASP.NET DropDownList control?

Private Sub YourWebPage_PreRenderComplete(sender As Object, e As EventArgs) Handles Me.PreRenderComplete

     If Not IsPostBack Then
     DropDownList1.Items.Insert(0, "Select")
     End If

End Sub

Can't compile C program on a Mac after upgrade to Mojave

I tried almost all the posted solutions and nothing worked for me. I use Mojave OS (10.14.6) and what finally worked for me (after removing and re-installing Xcode and CLTs and SDK headers):

  1. Install Clang v8 from
  2. Modify the following lines from ~/.R/Makevars file
CC=/usr/local/opt/llvm/bin/clang -fopenmp


CC=/usr/local/clang8/bin/clang -fopenmp

Now R packages that rely on C compilers install successfully

Ordering by specific field value first

One way is this:

select id, name, priority from table a
order by case when name='core' then -1 else priority end asc, priority asc

How to cast an object in Objective-C

Typecasting in Objective-C is easy as:

NSArray *threeViews = @[[UIView new], [UIView new], [UIView new]];
UIView *firstView = (UIView *)threeViews[0];

However, what happens if first object is not UIView and you try to use it:

NSArray *threeViews = @[[NSNumber new], [UIView new], [UIView new]];
UIView *firstView = (UIView *)threeViews[0];
CGRect firstViewFrame = firstView.frame; // CRASH!

It will crash. And it's easy to find such crash for this case, but what if those lines are in different classes and the third line is executed only once in 100 cases. I bet your customers find this crash, not you! A plausible solution is to crash early, like this:

UIView *firstView = (UIView *)threeViews[0];
NSAssert([firstView isKindOfClass:[UIView class]], @"firstView is not UIView");

Those assertions doesn't look very nice, so we could improve them with this handy category:

@interface NSObject (TypecastWithAssertion)
+ (instancetype)typecastWithAssertion:(id)object;

@implementation NSObject (TypecastWithAssertion)

+ (instancetype)typecastWithAssertion:(id)object {
    if (object != nil)
        NSAssert([object isKindOfClass:[self class]], @"Object %@ is not kind of class %@", object, NSStringFromClass([self class]));
    return object;


This is much better:

UIView *firstView = [UIView typecastWithAssertion:[threeViews[0]];

P.S. For collections type safety Xcode 7 have a much better than typecasting - generics

How can I display a list view in an Android Alert Dialog?

Use the "import;" import and then you write

    String[] items = {"...","...."};             
    AlertDialog.Builder build = new AlertDialog.Builder(context);
    build.setItems(items, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            //do stuff....

'printf' with leading zeros in C

Your format specifier is incorrect. From the printf() man page on my machine:

0 A zero '0' character indicating that zero-padding should be used rather than blank-padding. A '-' overrides a '0' if both are used;

Field Width: An optional digit string specifying a field width; if the output string has fewer characters than the field width it will be blank-padded on the left (or right, if the left-adjustment indicator has been given) to make up the field width (note that a leading zero is a flag, but an embedded zero is part of a field width);

Precision: An optional period, '.', followed by an optional digit string giving a precision which specifies the number of digits to appear after the decimal point, for e and f formats, or the maximum number of characters to be printed from a string; if the digit string is missing, the precision is treated as zero;

For your case, your format would be %09.3f:

#include <stdio.h>

int main(int argc, char **argv)
  printf("%09.3f\n", 4917.24);
  return 0;


$ make testapp
cc     testapp.c   -o testapp
$ ./testapp 

Note that this answer is conditional on your embedded system having a printf() implementation that is standard-compliant for these details - many embedded environments do not have such an implementation.

What languages are Windows, Mac OS X and Linux written in?

I have read or heard that Mac OS X is written mostly in Objective-C with some of the lower level parts, such as the kernel, and hardware device drivers written in C. I believe that Apple "eat(s) its own dog food", meaning that they write Mac OS X using their own Xcode Developer Tools. The GCC(GNU Compiler Collection) compiler-linker is the unix command line tool that xCode used for most of its compiling and/or linking of executables. Among other possible languages, I know GCC compiles source code from the C, Objective-C, C++ and Objective-C++ languages.

How to find out when a particular table was created in Oracle?

Try this query:

SELECT sysdate FROM schema_name.table_name;

This should display the timestamp that you might need.

How do you find out the type of an object (in Swift)?

Old question, but this works for my need (Swift 5.x):

print(type(of: myObjectName))

How to get first character of a string in SQL?

LEFT(colName, 1) will also do this, also. It's equivalent to SUBSTRING(colName, 1, 1).

I like LEFT, since I find it a bit cleaner, but really, there's no difference either way.

Call an angular function inside html

Yep, just add parenthesis (calling the function). Make sure the function is in scope and actually returns something.

<ul class="ui-listview ui-radiobutton" ng-repeat="meter in meters">
  <li class = "ui-divider">
    {{ meter.DESCRIPTION }}
    {{ htmlgeneration() }}

XMLHttpRequest (Ajax) Error

The problem is likely to lie with the line:

window.onload = onPageLoad();

By including the brackets you are saying onload should equal the return value of onPageLoad(). For example:

/*Example function*/
function onPageLoad()
    return "science";
/*Set on load*/
window.onload = onPageLoad()

If you print out the value of window.onload to the console it will be:


The solution is remove the brackets:

window.onload = onPageLoad;

So, you're using onPageLoad as a reference to the so-named function.

Finally, in order to get the response value you'll need a readystatechange listener for your XMLHttpRequest object, since it's asynchronous:

xmlDoc = xmlhttp.responseXML;
parser = new DOMParser(); // This code is untested as it doesn't run this far.

Here you add the listener:

xmlHttp.onreadystatechange = function() {
    if(this.readyState == 4) {
        // Do something

Using `window.location.hash.includes` throws “Object doesn't support property or method 'includes'” in IE11

I'm using ReactJs and used import 'core-js/es6/string'; at the start of index.js to solve my problem.

I'm also using import 'react-app-polyfill/ie11'; to support running React in IE11.


This package includes polyfills for various browsers. It includes minimum requirements and commonly used language features used by Create React App projects.

How to select records without duplicate on just one field in SQL?

select Country_id,country_title from(
   select Country_id,country_title,row_number() over (partition by country_title 
   order by Country_id  ) rn from country)a
   where rn=1;

How to get Android application id?

For getting AppId (or package name, how some says), just call this:

But be sure that you importing BuildConfig with your app id packages path


Save internal file in my own internal folder in Android

The answer of Mintir4 is fine, I would also do the following to load the file.

FileInputStream fis = myContext.openFileInput(fn);
BufferedReader r = new BufferedReader(new InputStreamReader(fis));
String s = "";

while ((s = r.readLine()) != null) {
    txt += s;


Split comma-separated values

.NET 2.0 does not support LINQ - SO thread;
But you can create a 3.5 project in VS2005 - MSDN thread

Without lambda support, you'll need to do something like this:

string s = "a,b, b, c";
string[] values = s.Split(',');
for(int i = 0; i < values.Length; i++)
   values[i] = values[i].Trim();

How to use variables in a command in sed?

This might work for you:

sed 's|$ROOT|'"${HOME}"'|g' >

jQuery - multiple $(document).ready ...?

It is important to note that each jQuery() call must actually return. If an exception is thrown in one, subsequent (unrelated) calls will never be executed.

This applies regardless of syntax. You can use jQuery(), jQuery(function() {}), $(document).ready(), whatever you like, the behavior is the same. If an early one fails, subsequent blocks will never be run.

This was a problem for me when using 3rd-party libraries. One library was throwing an exception, and subsequent libraries never initialized anything.

How to set timeout for a line of c# code

I use something like this (you should add code to deal with the various fails):

    var response = RunTaskWithTimeout<ReturnType>(
        (Func<ReturnType>)delegate { return SomeMethod(someInput); }, 30);

    /// <summary>
    /// Generic method to run a task on a background thread with a specific timeout, if the task fails,
    /// notifies a user
    /// </summary>
    /// <typeparam name="T">Return type of function</typeparam>
    /// <param name="TaskAction">Function delegate for task to perform</param>
    /// <param name="TimeoutSeconds">Time to allow before task times out</param>
    /// <returns></returns>
    private T RunTaskWithTimeout<T>(Func<T> TaskAction, int TimeoutSeconds)
        Task<T> backgroundTask;

            backgroundTask = Task.Factory.StartNew(TaskAction);
            backgroundTask.Wait(new TimeSpan(0, 0, TimeoutSeconds));
        catch (AggregateException ex)
            // task failed
            var failMessage = ex.Flatten().InnerException.Message);
            return default(T);
        catch (Exception ex)
            // task failed
            var failMessage = ex.Message;
            return default(T);

        if (!backgroundTask.IsCompleted)
            // task timed out
            return default(T);

        // task succeeded
        return backgroundTask.Result;

Can I mask an input text in a bat file?

I read all the clunky solutions on the net about how to mask passwords in a batch file, the ones from using a solution and even the ones that make the text and the background the same color. The solution works decent, it isn't very secure, and it doesn't work in 64-bit Windows. So anyway, using 100% Microsoft utilities, there is a way!

First, let me explain my use. I have about 20 workstations that auto logon to Windows. They have one shortcut on their desktop - to a clinical application. The machines are locked down, they can't right click, they can't do anything but access the one shortcut on their desktop. Sometimes it is necessary for a technician to kick up some debug applications, browse windows explorer and look at log files without logging the autolog user account off.

So here is what I have done.

Do it however you wish, but I put my two batch files on a network share that the locked down computer has access to.

My solution utilizes 1 main component of Windows - runas. Put a shortcut on the clients to the runas.bat you are about to create. FYI, on my clients I renamed the shortcut for better viewing purposes and changed the icon.

You will need to create two batch files.

I named the batch files runas.bat and Debug Support.bat

runas.bat contains the following code:

@echo off
goto menu

echo           ....................................
echo            ~Written by Cajun Wonder 4/1/2010~
echo           ....................................
@set /p un=What is your domain username? 
if "%un%"=="PUT-YOUR-DOMAIN-USERNAME-HERE" goto debugsupport
if not "%un%"=="PUT-YOUR-DOMAIN-USERNAME-HERE" goto noaccess
"%SYSTEMROOT%\system32\runas" /netonly /user:PUT-YOUR-DOMAIN-NAME-HERE\%un% "\\PUT-YOUR-NETWORK-SHARE-PATH-HERE\Debug Support.bat"
@ping -n 4 > NUL
goto quit
@echo   \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
@echo   \\                                   \\
@echo   \\    Insufficient privileges         \\  
@echo   \\                                    \\
@echo   \\      Call Cajun Wonder             \\
@echo   \\                                    \\
@echo   \\              At                    \\
@echo   \\                                    \\
@echo   \\        555-555-5555                \\
@echo   \\                                    \\
@echo   \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
@ping -n 4 > NUL
goto quit

You can add as many if "%un%" and if not "%un%" for all the users you want to give access to. The @ping is my coonass way of making a seconds timer.

So that takes care of the first batch file - pretty simple eh?

Here is the code for Debug Support.bat:

@echo off
goto menu

@echo %username%
echo           .....................................
echo            ~Written by Cajun Wonder 4/1/2010~
echo           .....................................
echo What do you want to do? 
echo [1]  Launch notepad

set /P C=[Option]? 
if "%C%"=="1" goto notepad
goto choice

@echo starting notepad....
@ping -n 3 > NUL
start notepad
goto menu

I'm not a coder and really just started getting into batch scripting about a year ago, and this round about way that I discovered of masking a password in a batch file is pretty awesome!

I hope to hear that someone other than me is able to get some use out of it!

Going through a text file line by line in C

In addition to the other answers, on a recent C library (Posix 2008 compliant), you could use getline. See this answer (to a related question).

How to pass command line arguments to a rake task

I couldn't figure out how to pass args and also the :environment until I worked this out:

namespace :db do
  desc 'Export product data'
  task :export, [:file_token, :file_path] => :environment do |t, args|
    args.with_defaults(:file_token => "products", :file_path => "./lib/data/")

       #do stuff [...]


And then I call like this:

rake db:export['foo, /tmp/']

Git push failed, "Non-fast forward updates were rejected"

You can add --force-with-lease to the command, it will works.

git push --force-with-lease

--force is destructive because it unconditionally overwrites the remote repository with whatever you have locally. But --force-with-lease ensure you don't overwrite other's work.

See more info here.

Android ListView with Checkbox and all clickable

Set the CheckBox as focusable="false" in your XML layout. Otherwise it will steal click events from the list view.

Of course, if you do this, you need to manually handle marking the CheckBox as checked/unchecked if the list item is clicked instead of the CheckBox, but you probably want that anyway.

How to update a claim in ASP.NET Identity?

Multiple Cookies,Multiple Claims

public class ClaimsCookie
        private readonly ClaimsPrincipal _user;
        private readonly HttpContext _httpContext;
        public ClaimsCookie(ClaimsPrincipal user, HttpContext httpContext = null)
            _user = user;
            _httpContext = httpContext;

        public string GetValue(CookieName cookieName, KeyName keyName)
            var principal = _user as ClaimsPrincipal;
            var cp = principal.Identities.First(i => i.AuthenticationType == ((CookieName)cookieName).ToString());
            return cp.FindFirst(((KeyName)keyName).ToString()).Value;
        public async void SetValue(CookieName cookieName, KeyName[] keyName, string[] value)
            if (keyName.Length != value.Length)
            var principal = _user as ClaimsPrincipal;
            var cp = principal.Identities.First(i => i.AuthenticationType == ((CookieName)cookieName).ToString());
            for (int i = 0; i < keyName.Length; i++)
                if (cp.FindFirst(((KeyName)keyName[i]).ToString()) != null)
                    cp.AddClaim(new Claim(((KeyName)keyName[i]).ToString(), value[i]));

            await _httpContext.SignOutAsync(CookieName.UserProfilCookie.ToString());
            await _httpContext.SignInAsync(CookieName.UserProfilCookie.ToString(), new ClaimsPrincipal(cp),
                new AuthenticationProperties
                    IsPersistent = bool.Parse(cp.FindFirst(KeyName.IsPersistent.ToString()).Value),
                    AllowRefresh = true
        public enum CookieName
            CompanyUserProfilCookie = 0, UserProfilCookie = 1, AdminPanelCookie = 2
        public enum KeyName
            Id, Name, Surname, Image, IsPersistent

What is the difference between "INNER JOIN" and "OUTER JOIN"?

  • Inner join - An inner join using either of the equivalent queries gives the intersection of the two tables, i.e. the two rows they have in common.

  • Left outer join - A left outer join will give all rows in A, plus any common rows in B.

  • Full outer join - A full outer join will give you the union of A and B, i.e. All the rows in A and all the rows in B. If something in A doesn't have a corresponding datum in B, then the B portion is null, and vice versay

Making view resize to its parent when added with addSubview

Swift 4 extension using explicit constraints:

import UIKit.UIView

extension UIView {
    public func addSubview(_ subview: UIView, stretchToFit: Bool = false) {
        if stretchToFit {
            subview.translatesAutoresizingMaskIntoConstraints = false
            leftAnchor.constraint(equalTo: subview.leftAnchor).isActive = true
            rightAnchor.constraint(equalTo: subview.rightAnchor).isActive = true
            topAnchor.constraint(equalTo: subview.topAnchor).isActive = true
            bottomAnchor.constraint(equalTo: subview.bottomAnchor).isActive = true


parentView.addSubview(childView) // won't resize (default behavior unchanged)
parentView.addSubview(childView, stretchToFit: false) // won't resize
parentView.addSubview(childView, stretchToFit: true) // will resize

"Invalid signature file" when attempting to run a .jar

Please use the following command

zip -d yourjar.jar 'META-INF/*.SF' 'META-INF/*.RSA' 'META-INF/*SF'

Difference between a Seq and a List in Scala

In Scala, a List inherits from Seq, but implements Product; here is the proper definition of List :

sealed abstract class List[+A] extends AbstractSeq[A] with Product with ...

[Note: the actual definition is a tad bit more complex, in order to fit in with and make use of Scala's very powerful collection framework.]

The equivalent of wrap_content and match_parent in flutter?

Use FractionallySizedBox widget.

  widthFactor: 1.0, // width w.r.t to parent
  heightFactor: 1.0,  // height w.r.t to parent
  child: *Your Child Here*

This widget is also very useful when you want to size your child at a fractional of its parent's size.


If you want the child to occupy 50% width of its parent, provide widthFactor as 0.5

MongoDB: How To Delete All Records Of A Collection in MongoDB Shell?

Delete all documents from a collection in cmd:

cd C:\Program Files\MongoDB\Server\4.2\bin
use yourdb
db.yourcollection.remove( { } )

How to export query result to csv in Oracle SQL Developer?

FYI, you can substitute the /*csv*/ for other formats as well including /*xml*/ and /*html*/. select /*xml*/ * from emp would return an xml document with the query results for example. I came across this article while looking for an easy way to return xml from a query.

How to create a temporary directory/folder in Java?

Well, "createTempFile" actually creates the file. So why not just delete it first, and then do the mkdir on it?

How to check Spark Version

According to the Cloudera documentation - What's New in CDH 5.7.0 it includes Spark 1.6.0.

How make background image on newsletter in outlook?

The only way I was able to do this is via this code (TD tables). I tested in outlook client 2010. I also tested via webmail client and it worked for both.

The only things you have to do is change your_image.jpg (there are two instances of this for the same image make sure you update both for your code) and #your_color.

<td bgcolor="#your_color" background="your_image.jpg">

<!--[if gte mso 9]>

<v:image xmlns:v="urn:schemas-microsoft-com:vml" id="theImage" style='behavior: url(#default#VML); display:inline-block; position:absolute; height:300px; width:600px; top:0; left:0; border:0; z-index:1;' src="your_image.jpg"/>

<v:shape xmlns:v="urn:schemas-microsoft-com:vml" id="theText" style='behavior: url(#default#VML); display:inline-block; position:absolute; height:300px; width:600px; top:-5; left:-10; border:0; z-index:2;'>


<p>Text over background image.</p>

<!--[if gte mso 9]>





Factory Pattern. When to use factory methods?

Factory classes are more heavyweight, but give you certain advantages. In cases when you need to build your objects from multiple, raw data sources they allow you to encapsulate only the building logic (and maybe the aggregation of the data) in one place. There it can be tested in abstract without being concerned with the object interface.

I have found this a useful pattern, particularly where I am unable to replace and inadequate ORM and want to efficiently instantiate many objects from DB table joins or stored procedures.

Html.fromHtml deprecated in Android N

Try the following to support basic html tags including ul ol li tags. Create a Tag handler as shown below

import org.xml.sax.XMLReader;

import android.os.Bundle;
import android.text.Editable;
import android.text.Html;
import android.text.Html.TagHandler;
import android.util.Log;

public class MyTagHandler implements TagHandler {
    boolean first= true;
    String parent=null;
    int index=1;
    public void handleTag(boolean opening, String tag, Editable output,
                          XMLReader xmlReader) {

        if(tag.equals("ul")) parent="ul";
        else if(tag.equals("ol")) parent="ol";
                    first= false;
                    first = true;
                    output.append("\n\t"+index+". ");
                    first= false;
                    first = true;

Set the text on Activity as shown below

    public void init(){
        try {
            TextView help = (TextView) findViewById(;
            if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
                help.setText(Html.fromHtml(getString(R.string.help_html),Html.FROM_HTML_MODE_LEGACY, null, new MyTagHandler()));
            } else {
                help.setText(Html.fromHtml(getString(R.string.help_html), null, new MyTagHandler()));
        } catch (Exception e) {


And html text on resource string files as

<![CDATA[ ...raw html data ...]] >

Call to a member function on a non-object

I realized that I wasn't passing $objPage into page_properties(). It works fine now.

What is a Java String's default initial value?

It's initialized to null if you do nothing, as are all reference types.

Warning about SSL connection when connecting to MySQL database

I found this warning too then I fixed it by using SSL=false suffix to the connection string like this example code.


connectionString = "jdbc:mysql://{server-name}:3306/%s?useUnicode=yes&characterEncoding=UTF-8&useSSL=false"

How to parse JSON without JSON.NET library?

You can use the classes found in the System.Json Namespace which were added in .NET 4.5. You need to add a reference to the System.Runtime.Serialization assembly

The JsonValue.Parse() Method parses JSON text and returns a JsonValue:

JsonValue value = JsonValue.Parse(@"{ ""name"":""Prince Charming"", ...");

If you pass a string with a JSON object, you should be able to cast the value to a JsonObject:

using System.Json;

JsonObject result = value as JsonObject;

Console.WriteLine("Name .... {0}", (string)result["name"]);
Console.WriteLine("Artist .. {0}", (string)result["artist"]);
Console.WriteLine("Genre ... {0}", (string)result["genre"]);
Console.WriteLine("Album ... {0}", (string)result["album"]);

The classes are quite similar to those found in the System.Xml.Linq Namespace.

Determine the number of lines within a text file

count the carriage returns/line feeds. I believe in unicode they are still 0x000D and 0x000A respectively. that way you can be as efficient or as inefficient as you want, and decide if you have to deal with both characters or not

How to check if a variable exists in a FreeMarker template?

Also I think if_exists was used like:

Hi ${userName?if_exists}, How are you?

which will not break if userName is null, the result if null would be:

Hi , How are you?

if_exists is now deprecated and has been replaced with the default operator ! as in

Hi ${userName!}, How are you?

the default operator also supports a default value, such as:

Hi ${userName!"John Doe"}, How are you?

Uncaught ReferenceError: React is not defined

I got this error because I was using

import ReactDOM from 'react-dom'

without importing react, once I changed it to below:

import React from 'react';
import ReactDOM from 'react-dom';

The error was solved :)

Django URLs TypeError: view must be a callable or a list/tuple in the case of include()

You may also get this error if you have a name clash of a view and a module. I've got the error when i distribute my view files under views folder, /views/, /views/ and imported some model named in which happened to be a name of a view in So naming the view functions as v_table(request,id) helped.

Rails server says port already used, how to kill that process?

One line solution:

kill -9 $(ps aux | grep 'rails s' | awk {'print$2'}); rails s

Remove Null Value from String array in java

A gc-friendly piece of code:

public static<X> X[] arrayOfNotNull(X[] array) {
    for (int p=0, N=array.length; p<N; ++p) {
        if (array[p] == null) {
            int m=p; for (int i=p+1; i<N; ++i) if (array[i]!=null) ++m;
            X[] res = Arrays.copyOf(array, m);
            for (int i=p+1; i<N; ++i) if (array[i]!=null) res[p++] = array[i];
            return res;
    return array;

It returns the original array if it contains no nulls. It does not modify the original array.

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

Don't know if you resolved this problem, but I have just resolved the same issue from the other side.

It appears Selenium and Firefox have difficulty talking to each other - I suspect Firefox 'evolve' changes over a number of releases, so backward and forward compatibility are not always guaranteed, and incompatibility always seems to generate the same error.

My problem started when I moved from FF 15 to FF 16. Running on Ubuntu, this happens auto magically along with other upgrades but I believe this was the critical change.

The problem was resolved by moving from Selenium 2.24.1 to Selenium 2.25.0

As the selenium change is just download the jar file and run it instead of the old one,it's worth trying this as a quick and easy troubleshooter - if it doesn't help, just switch back. In your case, I'm not sure which version of Selenium to try, but I think 2.24 should work with FF 10.

Another issue I have found in the past is that Firefox would not run as root on Ubuntu. This happens if Selenium is running as a service, or possibly if it is fired up from a bash script or cron job. This may explain why it runs for you but not for Jenkins.

How do I convert certain columns of a data frame to become factors?

Given the following sample

myData <- data.frame(A=rep(1:2, 3), B=rep(1:3, 2), Pulse=20:25)  


myData$A <-as.factor(myData$A)
myData$B <-as.factor(myData$B)

or you could select your columns altogether and wrap it up nicely:

# select columns
cols <- c("A", "B")
myData[,cols] <- data.frame(apply(myData[cols], 2, as.factor))

levels(myData$A) <- c("long", "short")
levels(myData$B) <- c("1kg", "2kg", "3kg")

To obtain

> myData
      A   B Pulse
1  long 1kg    20
2 short 2kg    21
3  long 3kg    22
4 short 1kg    23
5  long 2kg    24
6 short 3kg    25

Cannot find module '../build/Release/bson'] code: 'MODULE_NOT_FOUND' } js-bson: Failed to load c++ bson extension, using pure JS version

Short answer

Install the latest version of mongodb.

A little longer answer

Make sure your package.json is using the latest version of mongodb, then remove node_modules/mongodb and do npm install again. If you didn't use mongodb as a direct dependency, try to find which package is using mongdb. I used:

find . -type f -name package.json | xargs grep mongodb
./sails-mongo/package.json:    "mongodb": "1.4.26",

So I updated ./sails-mongo/package.json to:

"mongodb": "2.1.7",

Then remove node_modules/mongodb and do npm install again. Seems fine now.

Even longer answer

I don't like the current suggested way of using


Since looking at ../browser_build/bson.js, a 4k+ lines file, which seem also a "non-native" implementation. So although it won't spit out any complains, it is still "using pure JS version", which means slower performance.

Looking at and, it seems like the issue was caused by:

antoniofruci commented on Sep 15, 2015

I just found out that c++ code has been moved out 6 months ago and it is now an optional dependency: bson-ext. Indeed, if you install latest version no error occurs.

So I tried to remove the whole node_modules and still got the same error. And looking at package.json of node_modules/mongodb, its version is still 1.4.26, not latest 2.1.7.

Apparently my mongodb comes as a dependency of another package I installed: sails-mongo. Modifying the package.json of sails-mongo and redoing npm install finally solve the issue.

PHP Fatal error: Class 'PDO' not found

If you run php with php-fpm module,do not forget to run command systemctl restart php-fpm!That will reload php-fpm module.

variable or field declared void

Other answers have given very accurate responses and I am not completely sure what exactly was your problem(if it was just due to unknown type in your program then you would have gotten many more clear cut errors along with the one you mentioned) but to add on further information this error is also raised if we add the function type as void while calling the function as you can see further below:

using namespace std;
void fun(int x);
   int q=9;
   void fun(q); //line no 10
void fun(int x)
    if (x==9)


 C:\Users\ACER\Documents\C++ programs\exp1.cpp|10|error: variable or field 'fun' declared void|
||=== Build failed: 1 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

So as we can see from this example this reason can also result in "variable or field declared void" error.

Better way to convert file sizes in Python

There is hurry.filesize that will take the size in bytes and make a nice string out if it.

>>> from hurry.filesize import size
>>> size(11000)
>>> size(198283722)

Or if you want 1K == 1000 (which is what most users assume):

>>> from hurry.filesize import size, si
>>> size(11000, system=si)
>>> size(198283722, system=si)

It has IEC support as well (but that wasn't documented):

>>> from hurry.filesize import size, iec
>>> size(11000, system=iec)
>>> size(198283722, system=iec)

Because it's written by the Awesome Martijn Faassen, the code is small, clear and extensible. Writing your own systems is dead easy.

Here is one:

mysystem = [
    (1024 ** 5, ' Megamanys'),
    (1024 ** 4, ' Lotses'),
    (1024 ** 3, ' Tons'), 
    (1024 ** 2, ' Heaps'), 
    (1024 ** 1, ' Bunches'),
    (1024 ** 0, ' Thingies'),

Used like so:

>>> from hurry.filesize import size
>>> size(11000, system=mysystem)
'10 Bunches'
>>> size(198283722, system=mysystem)
'189 Heaps'

system("pause"); - Why is it wrong?


is wrong because it's part of Windows API and so it won't work in other operation systems.

You should try to use just objects from C++ standard library. A better solution will be to write:

return 0;

But it will also cause problems if you have other cins in your code. Because after each cin, you'll tap an Enter or \n which is a white space character. cin ignores this character and leaves it in the buffer zone but cin.get(), gets this remained character. So the control of the program reaches the line return 0 and the console gets closed before letting you see the results.
To solve this, we write the code as follows:

return 0;

List<Object> and List<?>

List is an interface so you can't instanciate it. Use any of its implementatons instead e.g.

List<Object> object = new List<Object>();

About List : you can use any object as a generic param for it instance:

List<?> list = new ArrayList<String>();


List<?> list = new ArrayList<Integer>();

While using List<Object> this declaration is invalid because it will be type missmatch.

How to stop IIS asking authentication for default website on localhost

It could be because of couple of Browser settings. Try with these options checked..

Tools > Internet Options > Advanced > Enable Integrated Windows Authentication (works with Integrated Windows Authentication set on IIS)

Tools > Internet Options> Security > Local Intranet > Custom Level > Automatic Logon

Worst case, try adding localhost to the Trusted sites.

If you are in a network, you can also try debugging by getting a network trace. Could be because of some proxy trying to authenticate.

Node.js spawn child process and get terminal output live

I found myself requiring this functionality often enough that I packaged it into a library called std-pour. It should let you execute a command and view the output in real time. To install simply:

npm install std-pour

Then it's simple enough to execute a command and see the output in realtime:

const { pour } = require('std-pour');
pour('ping', ['', '-c', '4']).then(code => console.log(`Error Code: ${code}`));

It's promised based so you can chain multiple commands. It's even function signature-compatible with child_process.spawn so it should be a drop in replacement anywhere you're using it.

Simple tool to 'accept theirs' or 'accept mine' on a whole file using git

Based on Jakub's answer you can configure the following git aliases for convenience:

accept-ours = "!f() { git checkout --ours -- \"${@:-.}\"; git add -u \"${@:-.}\"; }; f"
accept-theirs = "!f() { git checkout --theirs -- \"${@:-.}\"; git add -u \"${@:-.}\"; }; f"

They optionally take one or several paths of files to resolve and default to resolving everything under the current directory if none are given.

Add them to the [alias] section of your ~/.gitconfig or run

git config --global alias.accept-ours '!f() { git checkout --ours -- "${@:-.}"; git add -u "${@:-.}"; }; f'
git config --global alias.accept-theirs '!f() { git checkout --theirs -- "${@:-.}"; git add -u "${@:-.}"; }; f'

Changing factor levels with dplyr mutate

You can use the recode function from dplyr.

df <- iris %>%
     mutate(Species = recode(Species, setosa = "SETOSA",
         versicolor = "VERSICOLOR",
         virginica = "VIRGINICA"

How can I get Apache gzip compression to work?

If your Web Host is through C Panel Enable G ZIP Compression on Apache C Panel

Go to CPanel and check for software tab.

Previously Optimize website used to work but now a new option is available i.e "MultiPHP INI Editor".

Select the domain name you want to compress.

Scroll down to bottom until you find zip output compression and enable it.

Now check again for the G ZIP Compression.

You can follow the video tutorial also.

How to get the current time in Python

if you are using numpy already then directly you can use numpy.datetime64() function.

import numpy as np

for only date:


or, if you are using pandas already then you can use pandas.to_datetime() function

import pandas as pd



Test only if variable is not null in if statement

I don't believe the expression is sensical as it is.

Elvis means "if truthy, use the value, else use this other thing."

Your "other thing" is a closure, and the value is status != null, neither of which would seem to be what you want. If status is null, Elvis says true. If it's not, you get an extra layer of closure.

Why can't you just use:

(it.description == desc) && ((status == null) || (it.status == status))

Even if that didn't work, all you need is the closure to return the appropriate value, right? There's no need to create two separate find calls, just use an intermediate variable.

How to get the current directory of the cmdlet being executed

Most answers don't work when debugging in the following IDEs:

  • PS-ISE (PowerShell ISE)
  • VS Code (Visual Studio Code)

Because in those the $PSScriptRoot is empty and Resolve-Path .\ (and similars) will result in incorrect paths.

Freakydinde's answer is the only one that resolves those situations, so I up-voted that, but I don't think the Set-Location in that answer is really what is desired. So I fixed that and made the code a little clearer:

$directorypath = if ($PSScriptRoot) { $PSScriptRoot } `
    elseif ($psise) { split-path $psise.CurrentFile.FullPath } `
    elseif ($psEditor) { split-path $psEditor.GetEditorContext().CurrentFile.Path }

Why would one use nested classes in C++?

Nested classes are cool for hiding implementation details.


class List
        List(): head(nullptr), tail(nullptr) {}
        class Node
                  int   data;
                  Node* next;
                  Node* prev;
        Node*     head;
        Node*     tail;

Here I don't want to expose Node as other people may decide to use the class and that would hinder me from updating my class as anything exposed is part of the public API and must be maintained forever. By making the class private, I not only hide the implementation I am also saying this is mine and I may change it at any time so you can not use it.

Look at std::list or std::map they all contain hidden classes (or do they?). The point is they may or may not, but because the implementation is private and hidden the builders of the STL were able to update the code without affecting how you used the code, or leaving a lot of old baggage laying around the STL because they need to maintain backwards compatibility with some fool who decided they wanted to use the Node class that was hidden inside list.

SQL Server : SUM() of multiple rows including where clauses

The WHERE clause is always conceptually applied (the execution plan can do what it wants, obviously) prior to the GROUP BY. It must come before the GROUP BY in the query, and acts as a filter before things are SUMmed, which is how most of the answers here work.

You should also be aware of the optional HAVING clause which must come after the GROUP BY. This can be used to filter on the resulting properties of groups after GROUPing - for instance HAVING SUM(Amount) > 0

How to change status bar color in Flutter?

What you want is Themes. They're important for a lot more than the AppBar color.

Disable clipboard prompt in Excel VBA on workbook close

proposed solution edit works if you replace the row

Set rDst = ThisWorkbook.Sheets("SomeSheet").Cells("YourCell").Resize(rSrc.Rows.Count, rSrc.Columns.Count)


Set rDst = ThisWorkbook.Sheets("SomeSheet").Range("YourRange").Resize(rSrc.Rows.Count, rSrc.Columns.Count)

How to open VMDK File of the Google-Chrome-OS bundle 2012?

This is for vmware workstation 6.5

It is pretty far down.

select Create new virtual machine -> select custom ->
on compatibility page take defaults ->
check I will install os later -> click through several pages choosing other for OS, give it a name, make sure it IS NOT in the same folder as the VMDK file. Choose bridged network.

You will now see a screen asking to select disk, select existing virual disk. then browse and select the VMDK file

Convert a SQL Server datetime to a shorter date format

If you have a datetime field that gives the results like this 2018-03-30 08:43:28.177

Proposed: and you want to change the datetime to date to appear like 2018-03-30

cast(YourDateField as Date)

jQuery - Follow the cursor with a DIV

This works for me. Has a nice delayed action going on.

var $mouseX = 0, $mouseY = 0;
var $xp = 0, $yp =0;

    $mouseX = e.pageX;
    $mouseY = e.pageY;    

var $loop = setInterval(function(){
// change 12 to alter damping higher is slower
$xp += (($mouseX - $xp)/12);
$yp += (($mouseY - $yp)/12);
$("#moving_div").css({left:$xp +'px', top:$yp +'px'});  
}, 30);

Nice and simples

How to write text on a image in windows using python opencv2

Here's the code with parameter labels

def draw_text(self, frame, text, x, y, color=BGR_COMMON['green'], thickness=1.3, size=0.3,):
    if x is not None and y is not None:
            frame, text, (int(x), int(y)), cv2.FONT_HERSHEY_SIMPLEX, size, color, thickness)

For font name please see another answer in this thread.

Excerpt from answer by @Roeffus

This is indeed a bit of an annoying problem. For python 2.x.x you use:

cv2.CV_FONT_HERSHEY_SIMPLEX and for Python 3.x.x:


For more see this

How to get last key in an array?

As of PHP7.3 you can directly access the last key in (the outer level of) an array with array_key_last()

The definitively puts much of the debate on this page to bed. It is hands-down the best performer, suffers no side effects, and is a direct, intuitive, single-call technique to deliver exactly what this question seeks.

A rough benchmark as proof:

array_slice() + key():  1.4
end() + key():         13.7
array_key_last():       0.00015

*test array contains 500000 elements, microtime repeated 100x then averaged then multiplied by 1000 to avoid scientific notation. Credit to @MAChitgarha for the initial benchmark commented under @TadejMagajna's answer.

This means you can retrieve the value of the final key without:

  1. moving the array pointer (which requires two lines of code) or
  2. sorting, reversing, popping, counting, indexing an array of keys, or any other tomfoolery

This function was long overdue and a welcome addition to the array function tool belt that improves performance, avoids unwanted side-effects, and enables clean/direct/intuitive code.

Here is a demo:

$array = ["a" => "one", "b" => "two", "c" => "three"];
if (!function_exists('array_key_last')) {
    echo "please upgrade to php7.3";
} else {
    echo "First Key: " , key($array) , "\n";
    echo "Last Key: " , array_key_last($array) , "\n";
    next($array);                 // move array pointer to second element
    echo "Second Key: " , key($array) , "\n";
    echo "Still Last Key: " , array_key_last($array);


First Key: a
Last Key: c     // <-- unaffected by the pointer position, NICE!
Second Key: b
Last Key: c     // <-- unaffected by the pointer position, NICE!

Some notes:

  • array_key_last() is the sibling function of array_key_first().
  • Both of these functions are "pointer-ignorant".
  • Both functions return null if the array is empty.
  • Discarded sibling functions (array_value_first() & array_value_last()) also would have offered the pointer-ignorant access to bookend elements, but they evidently failed to garner sufficient votes to come to life.

Here are some relevant pages discussing the new features:

p.s. If anyone is weighing up some of the other techniques, you may refer to this small collection of comparisons: (Demo)

Duration of array_slice() + key():     0.35353660583496
Duration of end() + key():             6.7495584487915
Duration of array_key_last():          0.00025749206542969
Duration of array_keys() + end():      7.6123380661011
Duration of array_reverse() + key():   6.7875385284424
Duration of array_slice() + foreach(): 0.28870105743408

Difference between binary tree and binary search tree

A tree can be called as a binary tree if and only if the maximum number of children of any of the nodes is two.

A tree can be called as a binary search tree if and only if the maximum number of children of any of the nodes is two and the left child is always smaller than the right child.

Linking to an external URL in Javadoc?

Taken from the javadoc spec

@see <a href="URL#value">label</a> : Adds a link as defined by URL#value. The URL#value is a relative or absolute URL. The Javadoc tool distinguishes this from other cases by looking for a less-than symbol (<) as the first character.

For example : @see <a href="">Google</a>

Get number of digits with JavaScript

Problem statement: Count number/string not using string.length() jsfunction. Solution: we could do this through the Forloop. e.g

for (x=0; y>=1 ; y=y/=10){

if (x <= 10) {
  this.y = this.number;                

  this.number = this.y;


Better way to remove specific characters from a Perl string

You've misunderstood how character classes are used:

$varTemp =~ s/[\$#@~!&*()\[\];.,:?^ `\\\/]+//g;

does the same as your regex (assuming you didn't mean to remove ' characters from your strings).

Edit: The + allows several of those "special characters" to match at once, so it should also be faster.

How to save username and password in Git?

Attention: This method saves the credentials in plaintext on your PC's disk. Everyone on your computer can access it, e.g. malicious NPM modules.


git config --global credential.helper store


git pull

provide a username and password and those details will then be remembered later. The credentials are stored in a file on the disk, with the disk permissions of "just user readable/writable" but still in plaintext.

If you want to change the password later

git pull

Will fail, because the password is incorrect, git then removes the offending user+password from the ~/.git-credentials file, so now re-run

git pull

to provide a new password so it works as earlier.

How do you create a Marker with a custom icon for google maps API v3?


    var marker = new google.maps.Marker({
      position: map.getCenter(),
      icon: '',
      map: map

from here

How to update core-js to core-js@3 dependency?

With this

npm install --save core-js@^3

you now get the error

"core-js@<3 is no longer maintained and not recommended for usage due to the number of
issues. Please, upgrade your dependencies to the actual version of core-js@3"

so you might want to instead try

npm install --save core-js@3

if you're reading this post June 9 2020.

How to import a jar in Eclipse

Adding external Jar is not smart in case you want to change the project location in filesystem.

The best way is to add the jar to build path so your project will compile if exported:

  1. Create a folder called lib in your project folder.

  2. copy to this folder all the jar files you need.

  3. Refresh your project in eclipse.

  4. Select all the jar files, then right click on one of them and select Build Path -> Add to Build Path

Will using 'var' affect performance?

I don't think you properly understood what you read. If it gets compiled to the correct type, then there is no difference. When I do this:

var i = 42;

The compiler knows it's an int, and generate code as if I had written

int i = 42;

As the post you linked to says, it gets compiled to the same type. It's not a runtime check or anything else requiring extra code. The compiler just figures out what the type must be, and uses that.

Python: finding lowest integer

You have to start somewhere the correct code should be:

The code to return the minimum value

l = [ '0.0', '1','-1.2'] x = l[0] for i in l: if i < x: x = i print x

But again it's good to use directly integers instead of using quotations ''

This way!

l = [ 0.0, 1,-1.2] x = l[0] for i in l: if i < x: x = i print x

How to resolve /var/www copy/write permission denied?

Execute the following command

sudo setfacl -R -m u:<user_name>:rwx /var/www

It will change the permissions of html directory so that you can upload, download and delete the files or directories

Make Axios send cookies in its requests automatically

You can use withCredentials property to pass cookies in the request.

axios.get(`api_url`, { withCredentials: true })

By setting { withCredentials: true } you may encounter cross origin issue. To solve that you need to use

expressApp.use(cors({ credentials: true, origin: "http://localhost:8080" }));

Here you can read about withCredentials

How to calculate the sentence similarity using word2vec model of gensim with python

If not using Word2Vec we have other model to find it using BERT for embed. Below are reference link

pip install -U sentence-transformers

from sentence_transformers import SentenceTransformer
import scipy.spatial

embedder = SentenceTransformer('bert-base-nli-mean-tokens')

# Corpus with example sentences
corpus = ['A man is eating a food.',
          'A man is eating a piece of bread.',
          'The girl is carrying a baby.',
          'A man is riding a horse.',
          'A woman is playing violin.',
          'Two men pushed carts through the woods.',
          'A man is riding a white horse on an enclosed ground.',
          'A monkey is playing drums.',
          'A cheetah is running behind its prey.'
corpus_embeddings = embedder.encode(corpus)

# Query sentences:
queries = ['A man is eating pasta.', 'Someone in a gorilla costume is playing a set of drums.', 'A cheetah chases prey on across a field.']
query_embeddings = embedder.encode(queries)

# Find the closest 5 sentences of the corpus for each query sentence based on cosine similarity
closest_n = 5
for query, query_embedding in zip(queries, query_embeddings):
    distances = scipy.spatial.distance.cdist([query_embedding], corpus_embeddings, "cosine")[0]

    results = zip(range(len(distances)), distances)
    results = sorted(results, key=lambda x: x[1])

    print("Query:", query)
    print("\nTop 5 most similar sentences in corpus:")

    for idx, distance in results[0:closest_n]:
        print(corpus[idx].strip(), "(Score: %.4f)" % (1-distance))

Other Link to follow

Python requests - print entire http request (raw)?

A fork of @AntonioHerraizS answer (HTTP version missing as stated in comments)

Use this code to get a string representing the raw HTTP packet without sending it:

import requests

def get_raw_request(request):
    request = request.prepare() if isinstance(request, requests.Request) else request
    headers = '\r\n'.join(f'{k}: {v}' for k, v in request.headers.items())
    body = '' if request.body is None else request.body.decode() if isinstance(request.body, bytes) else request.body
    return f'{request.method} {request.path_url} HTTP/1.1\r\n{headers}\r\n\r\n{body}'

headers = {'User-Agent': 'Test'}
request = requests.Request('POST', '', headers=headers, json={"hello": "world"})
raw_request = get_raw_request(request)


User-Agent: Test
Content-Length: 18
Content-Type: application/json

{"hello": "world"}

Can also print the request in the response object

r = requests.get('')
raw_request = get_raw_request(r.request)

What is the best way to implement a "timer"?

Use the Timer class.

public static void Main()
    System.Timers.Timer aTimer = new System.Timers.Timer();
    aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
    aTimer.Interval = 5000;
    aTimer.Enabled = true;

    Console.WriteLine("Press \'q\' to quit the sample.");
    while(Console.Read() != 'q');

 // Specify what you want to happen when the Elapsed event is raised.
 private static void OnTimedEvent(object source, ElapsedEventArgs e)
     Console.WriteLine("Hello World!");

The Elapsed event will be raised every X amount of milliseconds, specified by the Interval property on the Timer object. It will call the Event Handler method you specify. In the example above, it is OnTimedEvent.

One line if-condition-assignment

Here is what i can suggest. Use another variable to derive the if clause and assign it to num1.


num2 =20 if someBoolValue else num1

Adding a Scrollable JTextArea (Java)

You don't need two JScrollPanes.


JTextArea ta = new JTextArea();
JScrollPane sp = new JScrollPane(ta);  

// Add the scroll pane into the content pane
JFrame f = new JFrame();

What does "O(1) access time" mean?

Introduction to Algorithms: Second Edition by Cormen, Leiserson, Rivest & Stein says on page 44 that

Since any constant is a degree-0 polynomial, we can express any constant function as Theta(n^0), or Theta(1). This latter notation is a minor abuse, however, because it is not clear what variable is tending to infinity. We shall often use the notation Theta(1) to mean either a constant or a constant function with respect to some variable. ... We denote by O(g(n))... the set of functions f(n) such that there exist positive constants c and n0 such that 0 <= f(n) <= c*g(n) for all n >= n0. ... Note that f(n) = Theta(g(n)) implies f(n) = O(g(n)), since Theta notation is stronger than O notation.

If an algorithm runs in O(1) time, it means that asymptotically doesn't depend upon any variable, meaning that there exists at least one positive constant that when multiplied by one is greater than the asymptotic complexity (~runtime) of the function for values of n above a certain amount. Technically, it's O(n^0) time.

Get Android Phone Model programmatically

For whom who looking for full list of properties of Build here is an example for Sony Z1 Compact:

Build.BOARD = MSM8974
Build.BRAND = Sony
Build.CPU_ABI = armeabi-v7a
Build.CPU_ABI2 = armeabi
Build.DEVICE = D5503
Build.DISPLAY = 14.6.A.1.236
Build.FINGERPRINT = Sony/D5503/D5503:5.1.1/14.6.A.1.236/2031203XXX:user/release-keys
Build.HARDWARE = qcom
Build.HOST = BuildHost
Build.ID = 14.6.A.1.236
Build.IS_DEBUGGABLE = false
Build.MODEL = D5503
Build.PRODUCT = D5503
Build.RADIO = unknown
Build.SUPPORTED_32_BIT_ABIS = [Ljava.lang.String;@3dd90541
Build.SUPPORTED_64_BIT_ABIS = [Ljava.lang.String;@1da4fc3
Build.SUPPORTED_ABIS = [Ljava.lang.String;@525f635
Build.TAGS = release-keys
Build.TIME = 144792559XXXX
Build.TYPE = user
Build.UNKNOWN = unknown
Build.USER = BuildUser

You can easily list those properties for your device in debug mode using "evaluate expression" dialog using kotlin: { "Build.${} = ${it.get(}"}.joinToString("\n")

Case-insensitive search


let string="Stackoverflow is the BEST";
let searchstring="best";

let found = string.toLowerCase()

includes() returns true if searchString appears at one or more positions or false otherwise.

Detect if Android device has Internet connection

private static NetworkUtil mInstance;
private volatile boolean mIsOnline;

private NetworkUtil() {
    ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor();
    exec.scheduleAtFixedRate(new Runnable() {
        public void run() {
            boolean reachable = false;
            try {
                Process process = java.lang.Runtime.getRuntime().exec("ping -c 1");
                int returnVal = process.waitFor();
                reachable = (returnVal==0);
            } catch (Exception e) {
            mIsOnline = reachable;
    }, 0, 5, TimeUnit.SECONDS);

public static NetworkUtil getInstance() {
    if (mInstance == null) {
        synchronized (NetworkUtil.class) {
            if (mInstance == null) {
                mInstance = new NetworkUtil();
    return mInstance;

public boolean isOnline() {
    return mIsOnline;

Hope the above code helps you, also make sure you have internet permission in ur app.

How to emulate a BEFORE INSERT trigger in T-SQL / SQL Server for super/subtype (Inheritance) entities?

While Andriy's proposal will work well for INSERTs of a small number of records, full table scans will be done on the final join as both 'enumerated' and '@new_super' are not indexed, resulting in poor performance for large inserts.

This can be resolved by specifying a primary key on the @new_super table, as follows:

DECLARE @new_super TABLE (
  super_id   int

This will result in the SQL optimizer scanning through the 'enumerated' table but doing an indexed join on @new_super to get the new key.

Is there a simple way that I can sort characters in a string in alphabetical order

You can use this

string x = "ABCGH"

char[] charX = x.ToCharArray();


This will sort your string.

Malformed String ValueError ast.literal_eval() with String representation of Tuple

ast.literal_eval (located in parses the tree with ast.parse first, then it evaluates the code with quite an ugly recursive function, interpreting the parse tree elements and replacing them with their literal equivalents. Unfortunately the code is not at all expandable, so to add Decimal to the code you need to copy all the code and start over.

For a slightly easier approach, you can use ast.parse module to parse the expression, and then the ast.NodeVisitor or ast.NodeTransformer to ensure that there is no unwanted syntax or unwanted variable accesses. Then compile with compile and eval to get the result.

The code is a bit different from literal_eval in that this code actually uses eval, but in my opinion is simpler to understand and one does not need to dig too deep into AST trees. It specifically only allows some syntax, explicitly forbidding for example lambdas, attribute accesses (foo.__dict__ is very evil), or accesses to any names that are not deemed safe. It parses your expression fine, and as an extra I also added Num (float and integer), list and dictionary literals.

Also, works the same on 2.7 and 3.3

import ast
import decimal

source = "(Decimal('11.66985'), Decimal('1e-8'),"\
    "(1,), (1,2,3), 1.2, [1,2,3], {1:2})"

tree = ast.parse(source, mode='eval')

# using the NodeTransformer, you can also modify the nodes in the tree,
# however in this example NodeVisitor could do as we are raising exceptions
# only.
class Transformer(ast.NodeTransformer):
    ALLOWED_NAMES = set(['Decimal', 'None', 'False', 'True'])
        'Expression', # a top node for an expression
        'Tuple',      # makes a tuple
        'Call',       # a function call (hint, Decimal())
        'Name',       # an identifier...
        'Load',       # loads a value of a variable with given identifier
        'Str',        # a string literal

        'Num',        # allow numbers too
        'List',       # and list literals
        'Dict',       # and dicts...

    def visit_Name(self, node):
        if not in self.ALLOWED_NAMES:
            raise RuntimeError("Name access to %s is not allowed" %

        # traverse to child nodes
        return self.generic_visit(node)

    def generic_visit(self, node):
        nodetype = type(node).__name__
        if nodetype not in self.ALLOWED_NODE_TYPES:
            raise RuntimeError("Invalid expression: %s not allowed" % nodetype)

        return ast.NodeTransformer.generic_visit(self, node)

transformer = Transformer()

# raises RuntimeError on invalid code

# compile the ast into a code object
clause = compile(tree, '<AST>', 'eval')

# make the globals contain only the Decimal class,
# and eval the compiled object
result = eval(clause, dict(Decimal=decimal.Decimal))


How to upgrade glibc from version 2.13 to 2.15 on Debian?

Your script contains errors as well, for example if you have dos2unix installed your install works but if you don't like I did then it will fail with dependency issues.

I found this by accident as I was making a script file of this to give to my friend who is new to Linux and because I made the scripts on windows I directed him to install it, at the time I did not have dos2unix installed thus I got errors.

here is a copy of the script I made for your solution but have dos2unix installed.

echo "deb sid main" >> /etc/apt/sources.list
apt-get update
apt-get -t sid install libc6 libc6-dev libc6-dbg
echo "Please remember to hash out sid main from your sources list. /etc/apt/sources.list"

this script has been tested on 3 machines with no errors.

How can I programmatically determine if my app is running in the iphone simulator?

With Swift 4.2 (Xcode 10), we can do this

#if targetEnvironment(simulator)
  //simulator code
  #warning("Not compiling for simulator")

Cannot find reference 'xxx' in - Python / Pycharm

I know this is old, but Google sent me here so I guess others will come too like me.

The answer on 2018 is the selected one here: Pycharm: "unresolved reference" error on the IDE when opening a working project

Just be aware that you can only add one Content Root but you can add several Source Folders. No need to touch files.

No value accessor for form control with name: 'recipient'

You should add the ngDefaultControl attribute to your input like this:


Taken from comments in this post:

angular2 rc.5 custom input, No value accessor for form control with unspecified name

Note: For later versions of @angular/material:

Nowadays you should instead write:



TypeError: $.ajax(...) is not a function?

I know this is an old posting -- and Gus basically answered it. But in my experience, JQuery has since changed their code for importing from the CDN - so I thought I would go ahead and post their latest code for importing from the CDN:

<script src="" integrity="sha256-9/aliU8dGd2tb6OSsuzixeV4y/faTqgFtohetphbbj0=" crossorigin="anonymous"></script>

How to efficiently check if variable is Array or Object (in NodeJS & V8)?

For simply checking against Object or Array without additional function call (speed).


isArray = function(a) {
    return (!!a) && (a.constructor === Array);
console.log(isArray(        )); // false
console.log(isArray(    null)); // false
console.log(isArray(    true)); // false
console.log(isArray(       1)); // false
console.log(isArray(   'str')); // false
console.log(isArray(      {})); // false
console.log(isArray(new Date)); // false
console.log(isArray(      [])); // true


isObject = function(a) {
    return (!!a) && (a.constructor === Object);
console.log(isObject(        )); // false
console.log(isObject(    null)); // false
console.log(isObject(    true)); // false
console.log(isObject(       1)); // false
console.log(isObject(   'str')); // false
console.log(isObject(      [])); // false
console.log(isObject(new Date)); // false
console.log(isObject(      {})); // true

Oracle - How to create a readonly user

create user ro_role identified by ro_role;
grant create session, select any table, select any dictionary to ro_role;

ORDER BY the IN value list

And here's another solution that works and uses a constant table (

SELECT * FROM comments AS c,
(VALUES (1,1),(3,2),(2,3),(4,4) ) AS t (ord_id,ord)
WHERE ( IN (1,3,2,4)) AND ( = t.ord_id)

But again I'm not sure that this is performant.

I've got a bunch of answers now. Can I get some voting and comments so I know which is the winner!

Thanks All :-)

How to convert hex to ASCII characters in the Linux shell?

Some python3 one-liners that work with any number of bytes.

Decoding hex (with strip, so that it's ok to have a newline on stdin):

$ echo 666f6f0a | python3 -c "import sys, binascii; sys.stdout.buffer.write(binascii.unhexlify(input().strip()))"

Encoding hex:

$ echo foo | python3 -c "import sys, binascii; print(binascii.hexlify("

How to set RelativeLayout layout params in code not in xml?

    RelativeLayout layout = new RelativeLayout(this);
    RelativeLayout.LayoutParams labelLayoutParams = new RelativeLayout.LayoutParams(
            LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

   // If you want to add some controls in this Relative Layout
    labelLayoutParams = new RelativeLayout.LayoutParams(
            LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

    ImageView mImage = new ImageView(this);


How to 'foreach' a column in a DataTable using C#?

int countRow = dt.Rows.Count;
int countCol = dt.Columns.Count;

for (int iCol = 0; iCol < countCol; iCol++)
     DataColumn col = dt.Columns[iCol];

     for (int iRow = 0; iRow < countRow; iRow++)
         object cell = dt.Rows[iRow].ItemArray[iCol];


How do I initialize a dictionary of empty lists in Python?

Use defaultdict instead:

from collections import defaultdict
data = defaultdict(list)

This way you don't have to initialize all the keys you want to use to lists beforehand.

What is happening in your example is that you use one (mutable) list:

alist = [1]
data = dict.fromkeys(range(2), alist)
print data

would output {0: [1, 2], 1: [1, 2]}.

Error Code: 1005. Can't create table '...' (errno: 150)

MyISAM has been just mentioned. Simply try adding ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; at the end of a statement, assuming that your other tables were created with MyISAM.

  `key` bigint(20) NOT NULL AUTO_INCREMENT,
  FOREIGN KEY `key` (`key`) REFERENCES `othertable`(`id`)

Java Switch Statement - Is "or"/"and" possible?

Observations on an interesting Switch case trap --> fall through of switch

"The break statements are necessary because without them, statements in switch blocks fall through:" Java Doc's example

Snippet of consecutive case without break:

    char c = 'A';/* switch with lower case */;
    switch(c) {
        case 'a':
        case 'A':

O/P for this case is:


But if you change value of c, i.e., char c = 'a';, then this get interesting.

O/P for this case is:

a A

Even though the 2nd case test fails, program goes onto print A, due to missing break which causes switch to treat the rest of the code as a block. All statements after the matching case label are executed in sequence.

Python: How to use RegEx in an if statement?

if'pattern', string):

Simple if-test:

if'ing\b', "seeking a great perhaps"):     # any words end with ing?

Pattern check, extract a substring, case insensitive:

match_object ='^OUGHT (.*) BE$', "ought to be", flags=re.IGNORECASE)
if match_object:
    assert "to" ==     # what's between ought and be?


  • Use not re.match. Match restricts to the start of strings, a confusing convention if you ask me. If you do want a string-starting match, use caret or \A instead,'^...', ...)

  • Use raw string syntax r'pattern' for the first parameter. Otherwise you would need to double up backslashes, as in'ing\\b', ...)

  • In this example, \b is a special sequence meaning word-boundary in regex. Not to be confused with backspace.

  • returns None if it doesn't find anything, which is always falsy.

  • returns a Match object if it finds anything, which is always truthy.

  • a group is what matched inside parentheses

  • group numbering starts at 1

  • Specs

  • Tutorial

How to convert a Title to a URL slug in jQuery?

private string ToSeoFriendly(string title, int maxLength) {
    var match = Regex.Match(title.ToLower(), "[\\w]+");
    StringBuilder result = new StringBuilder("");
    bool maxLengthHit = false;
    while (match.Success && !maxLengthHit) {
        if (result.Length + match.Value.Length <= maxLength) {
            result.Append(match.Value + "-");
        } else {
            maxLengthHit = true;
            // Handle a situation where there is only one word and it is greater than the max length.
            if (result.Length == 0) result.Append(match.Value.Substring(0, maxLength));
        match = match.NextMatch();
    // Remove trailing '-'
    if (result[result.Length - 1] == '-') result.Remove(result.Length - 1, 1);
    return result.ToString();

Modify request parameter with servlet filter

Try request.setAttribute("param",value);. It worked fine for me.

Please find this code sample:

private void sanitizePrice(ServletRequest request){
        if(request.getParameterValues ("price") !=  null){
            String price[] = request.getParameterValues ("price");

            for(int i=0;i<price.length;i++){
                price[i] = price[i].replaceAll("[^\\dA-Za-z0-9- ]", "").trim();
            request.setAttribute("price", price);

Concatenating variables and strings in React


        const json1 = [
            {id: 1, test: 1},
            {id: 2, test: 2},
            {id: 3, test: 3},
            {id: 4, test: 4},
            {id: 5, test: 5}

        const json2 = [
            {id: 3, test: 6},
            {id: 4, test: 7},
            {id: 5, test: 8},
            {id: 6, test: 9},
            {id: 7, test: 10}


        const finalData1 = json1.concat(json2).reduce(function (index, obj) {
            index[] = Object.assign({}, obj, index[]);
            return index;
        }, []).filter(function (res, obj) {
            return obj;


        let hashData = new Map();

        json1.concat(json2).forEach(function (obj) {
            hashData.set(, Object.assign(hashData.get( || {}, obj))

        const finalData2 = Array.from(hashData.values());

I recommend second example , it is faster.

How to get Python requests to trust a self signed SSL certificate?

The easiest is to export the variable REQUESTS_CA_BUNDLE that points to your private certificate authority, or a specific certificate bundle. On the command line you can do that as follows:

export REQUESTS_CA_BUNDLE=/path/to/your/certificate.pem

If you have your certificate authority and you don't want to type the export each time you can add the REQUESTS_CA_BUNDLE to your ~/.bash_profile as follows:

echo "export REQUESTS_CA_BUNDLE=/path/to/your/certificate.pem" >> ~/.bash_profile ; source ~/.bash_profile

Iterating over and deleting from Hashtable in Java

You need to use an explicit java.util.Iterator to iterate over the Map's entry set rather than being able to use the enhanced For-loop syntax available in Java 6. The following example iterates over a Map of Integer, String pairs, removing any entry whose Integer key is null or equals 0.

Map<Integer, String> map = ...

Iterator<Map.Entry<Integer, String>> it = map.entrySet().iterator();

while (it.hasNext()) {
  Map.Entry<Integer, String> entry =;

  // Remove entry if key is null or equals 0.
  if (entry.getKey() == null || entry.getKey() == 0) {

Error inflating class

I had issues including toolbar in a RelativeLayout, try with LinearLayout. If you want to overlay the toolbar, try with:





I don't understand why but it works for me.

Creating a JavaScript cookie on a domain and reading it across sub domains

You can also use the Cookies API and do:

  url: '',
  name: 'HelloWorld',
  value: 'HelloWorld',
  expirationDate: myDate

MDN Set() Method Documentation

Set Response Status Code

As written before, but for beginner like me don't forget to include the return.

return $this->response;

Python map object is not subscriptable

In Python 3, map returns an iterable object of type map, and not a subscriptible list, which would allow you to write map[i]. To force a list result, write

payIntList = list(map(int,payList))

However, in many cases, you can write out your code way nicer by not using indices. For example, with list comprehensions:

payIntList = [pi + 1000 for pi in payList]
for pi in payIntList:

How to make a variable accessible outside a function?

Your variable declarations and their scope are correct. The problem you are facing is that the first AJAX request may take a little bit time to finish. Therefore, the second URL will be filled with the value of sID before the its content has been set. You have to remember that AJAX request are normally asynchronous, i.e. the code execution goes on while the data is being fetched in the background.

You have to nest the requests:

$.getJSON(""+input+"?api_key=API_KEY_HERE"  , function(name){   obj = name;   // sID is only now available!   sID =;   console.log(sID); }); 

Clean up your code!

  • Put the second request into a function
  • and let it accept sID as a parameter, so you don't have to declare it globally anymore! (Global variables are almost always evil!)
  • Remove sID and obj variables - is sufficient unless you really need the other variables outside the function.

$.getJSON(""+input+"?api_key=API_KEY_HERE"  , function(name){   // We don't need sID or obj here - is sufficient   console.log(;    doSecondRequest(; });  /// TODO Choose a better name function doSecondRequest(sID) {   $.getJSON("" + sID + "/summary?api_key=API_KEY_HERE", function(stats){         console.log(stats);   }); } 

Hapy New Year :)

Enforcing the type of the indexed members of a Typescript object?

var stuff: { [key: string]: string; } = {};
stuff['a'] = ''; // ok
stuff['a'] = 4;  // error

// ... or, if you're using this a lot and don't want to type so much ...
interface StringMap { [key: string]: string; }
var stuff2: StringMap = { };
// same as above

Select dropdown with fixed width cutting off content in IE

for (i=1;i<=5;i++){
   idname = "Usert" + i;
   document.getElementById(idname).style.width = "100%";


I used this way to showed the drop down list when the width is not showed correctly.

It work for IE6, Firefox and Chrome.

Change bullets color of an HTML list without using span

If you can use an image then you can do this. And without an image you won't be able to change the color of the bullets only and not the text.

Using an image

li { list-style-image: url(images/yourimage.jpg); }



Without using an image

Then you have to edit the HTML markup and include a span inside the list and color the li and span with different colors.

Access denied for user 'test'@'localhost' (using password: YES) except root user

Try this:

If you have already created your user, you might have created your user with the wrong password.

So drop that user and create another user by doing this. To see your current users.

SELECT Host,User FROM mysql.user;

To drop the user

DROP User '<your-username>'@'localhost';

After this you can create the user again with the correct password

CREATE USER '<your-username>'@'localhost' IDENTIFIED WITH mysql_native_password BY '<correct password>';



You might still run into some more errors with getting access to the database, if you have that error run this.

GRANT ALL PRIVILEGES ON *.* to '<your-username>'@'localhost';

Hiding an Excel worksheet with VBA

Just wanted to add a little more detail to the answers given. You can also use

sheet.Visible = False

to hide and

sheet.Visible = True

to unhide.


How to launch Safari and open URL from iOS app

Here one check is required that the url going to be open is able to open by device or simulator or not. Because some times (majority in simulator) i found it causes crashes.


NSURL *url = [NSURL URLWithString:@"some url"];
if ([[UIApplication sharedApplication] canOpenURL:url]) {
   [[UIApplication sharedApplication] openURL:url];

Swift 2.0

let url : NSURL = NSURL(string: "some url")!
if UIApplication.sharedApplication().canOpenURL(url) {

Swift 4.2

guard let url = URL(string: "some url") else {
if UIApplication.shared.canOpenURL(url) {, options: [:], completionHandler: nil)

What do &lt; and &gt; stand for?

Others have noted the correct answer, but have not clearly explained the all-important reason:

  • why do we need this?

What do < and > stand for?

  • &lt; stands for the < sign. Just remember: lt == less than
  • &gt; stands for the > Just remember: gt == greater than

Why can’t we simply use the < and > characters in HTML?

  • This is because the > and < characters are ‘reserved’ characters in HTML.
  • HTML is a mark up language: The < and > are used to denote the starting and ending of different elements: e.g. <h1> and not for the displaying of the greater than or less than symbols. But what if you wanted to actually display those symbols? You would simply use &lt; and &gt; and the browser will know exactly how to display it.

Python list sort in descending order

This will give you a sorted version of the array.

sorted(timestamps, reverse=True)

If you want to sort in-place:


Bootstrap: change background color

You could hard code it.

<div class="col-md-6" style="background-color:blue;">

<div class="col-md-6" style="background-color:white;">

Exporting to .xlsx using Microsoft.Office.Interop.Excel SaveAs Error

    public static void ExportToExcel(DataGridView dgView)
        Microsoft.Office.Interop.Excel.Application excelApp = null;
            // instantiating the excel application class
            excelApp = new Microsoft.Office.Interop.Excel.Application();
            Microsoft.Office.Interop.Excel.Workbook currentWorkbook = excelApp.Workbooks.Add(Type.Missing);
            Microsoft.Office.Interop.Excel.Worksheet currentWorksheet = (Microsoft.Office.Interop.Excel.Worksheet)currentWorkbook.ActiveSheet;
            currentWorksheet.Columns.ColumnWidth = 18;

            if (dgView.Rows.Count > 0)
                currentWorksheet.Cells[1, 1] = DateTime.Now.ToString("s");
                int i = 1;
                foreach (DataGridViewColumn dgviewColumn in dgView.Columns)
                    // Excel work sheet indexing starts with 1
                    currentWorksheet.Cells[2, i] = dgviewColumn.Name;
                Microsoft.Office.Interop.Excel.Range headerColumnRange = currentWorksheet.get_Range("A2", "G2");
                headerColumnRange.Font.Bold = true;
                headerColumnRange.Font.Color = 0xFF0000;
                int rowIndex = 0;
                for (rowIndex = 0; rowIndex < dgView.Rows.Count; rowIndex++)
                    DataGridViewRow dgRow = dgView.Rows[rowIndex];
                    for (int cellIndex = 0; cellIndex < dgRow.Cells.Count; cellIndex++)
                        currentWorksheet.Cells[rowIndex + 3, cellIndex + 1] = dgRow.Cells[cellIndex].Value;
                Microsoft.Office.Interop.Excel.Range fullTextRange = currentWorksheet.get_Range("A1", "G" + (rowIndex + 1).ToString());
                fullTextRange.WrapText = true;
                fullTextRange.HorizontalAlignment = Microsoft.Office.Interop.Excel.XlHAlign.xlHAlignLeft;
                string timeStamp = DateTime.Now.ToString("s");
                timeStamp = timeStamp.Replace(':', '-');
                timeStamp = timeStamp.Replace("T", "__");
                currentWorksheet.Cells[1, 1] = timeStamp;
                currentWorksheet.Cells[1, 2] = "No error occured";
            using (SaveFileDialog exportSaveFileDialog = new SaveFileDialog())
                exportSaveFileDialog.Title = "Select Excel File";
                exportSaveFileDialog.Filter = "Microsoft Office Excel Workbook(*.xlsx)|*.xlsx";

                if (DialogResult.OK == exportSaveFileDialog.ShowDialog())
                    string fullFileName = exportSaveFileDialog.FileName;
                   // currentWorkbook.SaveCopyAs(fullFileName);
                    // indicating that we already saved the workbook, otherwise call to Quit() will pop up
                    // the save file dialogue box

                    currentWorkbook.SaveAs(fullFileName, Microsoft.Office.Interop.Excel.XlFileFormat.xlOpenXMLWorkbook, System.Reflection.Missing.Value, Missing.Value, false, false, Microsoft.Office.Interop.Excel.XlSaveAsAccessMode.xlNoChange, Microsoft.Office.Interop.Excel.XlSaveConflictResolution.xlUserResolution, true, Missing.Value, Missing.Value, Missing.Value);
                    currentWorkbook.Saved = true;
                    MessageBox.Show("Error memory exported successfully", "Exported to Excel", MessageBoxButtons.OK, MessageBoxIcon.Information);
        catch (Exception ex)
            MessageBox.Show(ex.Message, "Exception", MessageBoxButtons.OK, MessageBoxIcon.Error);
            if (excelApp != null)


PDO error message?

From the manual:

If the database server successfully prepares the statement, PDO::prepare() returns a PDOStatement object. If the database server cannot successfully prepare the statement, PDO::prepare() returns FALSE or emits PDOException (depending on error handling).

The prepare statement likely caused an error because the db would be unable to prepare the statement. Try testing for an error immediately after you prepare your query and before you execute it.

$qry = '
    INSERT INTO non-existant-table (id, score) 
    SELECT id, 40 
    FROM another-non-existant-table
    WHERE description LIKE "%:search_string%"
    AND available = "yes"
    ON DUPLICATE KEY UPDATE score = score + 40
$sth = $this->pdo->prepare($qry);

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

In my situation it was matter of the permissions:

 sudo chmod -R +777 <your_folder_path>

Subtracting Dates in Oracle - Number or Interval Datatype?

Ok, I don't normally answer my own questions but after a bit of tinkering, I have figured out definitively how Oracle stores the result of a DATE subtraction.

When you subtract 2 dates, the value is not a NUMBER datatype (as the Oracle 11.2 SQL Reference manual would have you believe). The internal datatype number of a DATE subtraction is 14, which is a non-documented internal datatype (NUMBER is internal datatype number 2). However, it is actually stored as 2 separate two's complement signed numbers, with the first 4 bytes used to represent the number of days and the last 4 bytes used to represent the number of seconds.

An example of a DATE subtraction resulting in a positive integer difference:

select date '2009-08-07' - date '2008-08-08' from dual;

Results in:


select dump(date '2009-08-07' - date '2008-08-08') from dual;

Typ=14 Len=8: 108,1,0,0,0,0,0,0

Recall that the result is represented as a 2 seperate two's complement signed 4 byte numbers. Since there are no decimals in this case (364 days and 0 hours exactly), the last 4 bytes are all 0s and can be ignored. For the first 4 bytes, because my CPU has a little-endian architecture, the bytes are reversed and should be read as 1,108 or 0x16c, which is decimal 364.

An example of a DATE subtraction resulting in a negative integer difference:

select date '1000-08-07' - date '2008-08-08' from dual;

Results in:


select dump(date '1000-08-07' - date '2008-08-08') from dual;

Typ=14 Len=8: 224,97,250,255,0,0,0,0

Again, since I am using a little-endian machine, the bytes are reversed and should be read as 255,250,97,224 which corresponds to 11111111 11111010 01100001 11011111. Now since this is in two's complement signed binary numeral encoding, we know that the number is negative because the leftmost binary digit is a 1. To convert this into a decimal number we would have to reverse the 2's complement (subtract 1 then do the one's complement) resulting in: 00000000 00000101 10011110 00100000 which equals -368160 as suspected.

An example of a DATE subtraction resulting in a decimal difference:

select to_date('08/AUG/2004 14:00:00', 'DD/MON/YYYY HH24:MI:SS'
 - to_date('08/AUG/2004 8:00:00', 'DD/MON/YYYY HH24:MI:SS') from dual;


The difference between those 2 dates is 0.25 days or 6 hours.

select dump(to_date('08/AUG/2004 14:00:00', 'DD/MON/YYYY HH24:MI:SS')
 - to_date('08/AUG/2004 8:00:00', 'DD/MON/YYYY HH24:MI:SS')) from dual;

Typ=14 Len=8: 0,0,0,0,96,84,0,0

Now this time, since the difference is 0 days and 6 hours, it is expected that the first 4 bytes are 0. For the last 4 bytes, we can reverse them (because CPU is little-endian) and get 84,96 = 01010100 01100000 base 2 = 21600 in decimal. Converting 21600 seconds to hours gives you 6 hours which is the difference which we expected.

Hope this helps anyone who was wondering how a DATE subtraction is actually stored.

You get the syntax error because the date math does not return a NUMBER, but it returns an INTERVAL:

SQL> SELECT DUMP(SYSDATE - start_date) from test;

Typ=14 Len=8: 188,10,0,0,223,65,1,0

You need to convert the number in your example into an INTERVAL first using the NUMTODSINTERVAL Function

For example:

SQL> SELECT (SYSDATE - start_date) DAY(5) TO SECOND from test;

+02748 22:50:04.000000

SQL> SELECT (SYSDATE - start_date) from test;


SQL> select NUMTODSINTERVAL(2748.9515, 'day') from dual;

+000002748 22:50:09.600000000


Based on the reverse cast with the NUMTODSINTERVAL() function, it appears some rounding is lost in translation.

How to close existing connections to a DB

You can use Cursor like that:

USE master

SET @Database = 'AdventureWorks2016CTP3'

SELECT spid FROM sys.sysprocesses WHERE DB_NAME(dbid) = @Database

OPEN Murderer


    SET @SQL = 'Kill ' + CAST(@SPID AS VARCHAR(10)) + ';'
    EXEC (@SQL)
    PRINT  ' Process ' + CAST(@SPID AS VARCHAR(10)) +' has been killed'

CLOSE Murderer

I wrote about that in my blog here:

Use a.empty, a.bool(), a.item(), a.any() or a.all()

As user2357112 mentioned in the comments, you cannot use chained comparisons here. For elementwise comparison you need to use &. That also requires using parentheses so that & wouldn't take precedence.

It would go something like this:

mask = ((50  < df['heart rate']) & (101 > df['heart rate']) & (140 < df['systolic...

In order to avoid that, you can build series for lower and upper limits:

low_limit = pd.Series([90, 50, 95, 11, 140, 35], index=df.columns)
high_limit = pd.Series([160, 101, 100, 19, 160, 39], index=df.columns)

Now you can slice it as follows:

mask = ((df < high_limit) & (df > low_limit)).all(axis=1)
     dyastolic blood pressure  heart rate  pulse oximetry  respiratory rate  \
17                        136          62              97                15   
69                        110          85              96                18   
72                        105          85              97                16   
161                       126          57              99                16   
286                       127          84              99                12   
435                        92          67              96                13   
499                       110          66              97                15   

     systolic blood pressure  temperature  
17                       141           37  
69                       155           38  
72                       154           36  
161                      153           36  
286                      156           37  
435                      155           36  
499                      149           36  

And for assignment you can use np.where:

df['class'] = np.where(mask, 'excellent', 'critical')

Get current time in milliseconds using C++ and Boost

If you mean milliseconds since epoch you could do

ptime time_t_epoch(date(1970,1,1)); 
ptime now = microsec_clock::local_time();
time_duration diff = now - time_t_epoch;
x = diff.total_milliseconds();

However, it's not particularly clear what you're after.

Have a look at the example in the documentation for DateTime at Boost Date Time

Java: Unresolved compilation problem

Your compiled classes may need to be recompiled from the source with the new jars.

Try running "mvn clean" and then rebuild

Place API key in Headers or URL

If you want an argument that might appeal to a boss: Think about what a URL is. URLs are public. People copy and paste them. They share them, they put them on advertisements. Nothing prevents someone (knowingly or not) from mailing that URL around for other people to use. If your API key is in that URL, everybody has it.

Python 3 Online Interpreter / Shell

I recently came across Python 3 interpreter at CompileOnline.

How do I catch a PHP fatal (`E_ERROR`) error?

PHP doesn't provide conventional means for catching and recovering from fatal errors. This is because processing should not typically be recovered after a fatal error. String matching an output buffer (as suggested by the original post the technique described on is definitely ill-advised. It's simply unreliable.

Calling the mail() function from within an error handler method prove to be problematic, too. If you had a lot of errors, your mail server would be loaded with work, and you could find yourself with a gnarly inbox. To avoid this, you might consider running a cron to scan error logs periodically and send notifications accordingly. You might also like to look into system monitoring software, such as Nagios.

To speak to the bit about registering a shutdown function:

It's true that you can register a shutdown function, and that's a good answer.

The point here is that we typically shouldn't try to recover from fatal errors, especially not by using a regular expression against your output buffer. I was responding to the accepted answer, which linked to a suggestion on which has since been changed or removed.

That suggestion was to use a regex against the output buffer during exception handling, and in the case of a fatal error (detected by the matching against whatever configured error text you might be expecting), try to do some sort of recovery or continued processing. That would not be a recommended practice (I believe that's why I can't find the original suggestion, too. I'm either overlooking it, or the php community shot it down).

It might be worth noting that the more recent versions of PHP (around 5.1) seem to call the shutdown function earlier, before the output buffering callback is envoked. In version 5 and earlier, that order was the reverse (the output buffering callback was followed by the shutdown function). Also, since about 5.0.5 (which is much earlier than the questioner's version 5.2.3), objects are unloaded well before a registered shutdown function is called, so you won't be able to rely on your in-memory objects to do much of anything.

So registering a shutdown function is fine, but the sort of tasks that ought to be performed by a shutdown function are probably limited to a handful of gentle shutdown procedures.

The key take-away here is just some words of wisdom for anyone who stumbles upon this question and sees the advice in the originally accepted answer. Don't regex your output buffer.

iFrame src change event detection?

Since version 3.0 of Jquery you might get an error

TypeError: url.indexOf is not a function

Which can be easily fix by doing

$('#iframe').on('load', function() {
    alert('frame has (re)loaded ');

How to make the script wait/sleep in a simple way in unity

With .Net 4.x you can use Task-based Asynchronous Pattern (TAP) to achieve this:

// .NET 4.x async-await
using UnityEngine;
using System.Threading.Tasks;
public class AsyncAwaitExample : MonoBehaviour
     private async void Start()
        await WaitOneSecondAsync();
        DoMoreStuff(); // Will not execute until WaitOneSecond has completed
    private async Task WaitOneSecondAsync()
        await Task.Delay(TimeSpan.FromSeconds(1));
        Debug.Log("Finished waiting.");

this is a feature to use .Net 4.x with Unity please see this link for description about it

and this link for sample project and compare it with coroutine

But becareful as documentation says that This is not fully replacement with coroutine

How to set a binding in Code?

You need to change source to viewmodel object:

myBinding.Source = viewModelObject;

Correct way to add external jars (lib/*.jar) to an IntelliJ IDEA project

Just copy-paste the .jar under the "libs" folder (or whole "libs" folder), right click on it and select 'Add as library' option from the list. It will do the rest...

enter image description here

How to copy the first few lines of a giant file, and add a line of text at the end of it using some Linux commands?

I am assuming what you are trying to achieve is to insert a line after the first few lines of of a textfile.

head -n10 file.txt >> newfile.txt
echo "your line >> newfile.txt
tail -n +10 file.txt >> newfile.txt

If you don't want to rest of the lines from the file, just skip the tail part.

Terminating idle mysql connections

Manual cleanup:

You can KILL the processid.

mysql> show full processlist;
| Id      | User       | Host              | db   | Command | Time  | State | Info                  |
| 1193777 | TestUser12 | | www  | Sleep   | 25946 |       | NULL                  |

mysql> kill 1193777;


  • the php application might report errors (or the webserver, check the error logs)
  • don't fix what is not broken - if you're not short on connections, just leave them be.

Automatic cleaner service ;)

Or you configure your mysql-server by setting a shorter timeout on wait_timeout and interactive_timeout

mysql> show variables like "%timeout%";
| Variable_name            | Value |
| connect_timeout          | 5     |
| delayed_insert_timeout   | 300   |
| innodb_lock_wait_timeout | 50    |
| interactive_timeout      | 28800 |
| net_read_timeout         | 30    |
| net_write_timeout        | 60    |
| slave_net_timeout        | 3600  |
| table_lock_wait_timeout  | 50    |
| wait_timeout             | 28800 |
9 rows in set (0.00 sec)

Set with:

set global wait_timeout=3;
set global interactive_timeout=3;

(and also set in your configuration file, for when your server restarts)

But you're treating the symptoms instead of the underlying cause - why are the connections open? If the PHP script finished, shouldn't they close? Make sure your webserver is not using connection pooling...

How to get an object's methods?

Get the Method Names:

var getMethodNames = function (obj) {
    return (Object.getOwnPropertyNames(obj).filter(function (key) {
        return obj[key] && (typeof obj[key] === "function");

Or, Get the Methods:

var getMethods     = function (obj) {
    return (Object.getOwnPropertyNames(obj).filter(function (key) {
        return obj[key] && (typeof obj[key] === "function");
    })).map(function (key) {
        return obj[key];

'sudo gem install' or 'gem install' and gem locations

Installing Ruby gems on a Mac is a common source of confusion and frustration. Unfortunately, most solutions are incomplete, outdated, and provide bad advice. I'm glad the accepted answer here says to NOT use sudo, which you should never need to do, especially if you don't understand what it does. While I used RVM years ago, I would recommend chruby in 2020.

Some of the other answers here provide alternative options for installing gems, but they don't mention the limitations of those solutions. What's missing is an explanation and comparison of the various options and why you might choose one over the other. I've attempted to cover most common scenarios in my definitive guide to installing Ruby gems on a Mac.

jquery dialog save cancel button styling

check out jquery ui 1.8.5 it's available here and it has the new button for dialog ui implementation

get string value from HashMap depending on key name

An important point to be noted here is that if your key is an object of user-defined class in java then make it a point to override the equals method. Because the HashMap.get(Object key) method uses the equals method for matching the key value. If you do not override the equals method then it will try to find the value simply based on the reference of the key and not the actual value of key in which case it will always return a null.

Creating a segue programmatically

Here is the code sample for Creating a segue programmatically:

class ViewController: UIViewController {
    // 1. Define the Segue
    private var commonSegue: UIStoryboardSegue!
    override func viewDidLoad() {
        // 2. Initialize the Segue
        self.commonSegue = UIStoryboardSegue(identifier: "CommonSegue", source: ..., destination: ...) {
            self.commonSegue.source.showDetailViewController(self.commonSegue.destination, sender: self)
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // 4. Prepare to perform the Segue
        if self.commonSegue == segue {
    func actionFunction() {
        // 3. Perform the Segue
        self.prepare(for: self.commonSegue, sender: self)

How do AX, AH, AL map onto EAX?

The below snippet examines EAX using GDB.

    (gdb) info register eax
    eax            0xaa55   43605
    (gdb) info register ax
    ax             0xaa55   -21931
    (gdb) info register ah
    ah             0xaa -86
    (gdb) info register al
    al             0x55 85
  1. EAX - Full 32 bit value
  2. AX - lower 16 bit value
  3. AH - Bits from 8 to 15
  4. AL - lower 8 bits of EAX/AX

Obtaining ExitCode using Start-Process and WaitForExit instead of -Wait

Here's a variation on this theme. I want to uninstall Cisco Amp, wait, and get the exit code. But the uninstall program starts a second program called "un_a" and exits. With this code, I can wait for un_a to finish and get the exit code of it, which is 3010 for "needs reboot". This is actually inside a .bat file.

If you've ever wanted to uninstall folding@home, it works in a similar way.

rem uninstall cisco amp, probably needs a reboot after

rem runs Un_A.exe and exits

rem start /wait isn't useful
"c:\program files\Cisco\AMP\6.2.19\uninstall.exe" /S

powershell while (! ($proc = get-process Un_A -ea 0)) { sleep 1 }; $handle = $proc.handle; 'waiting'; wait-process Un_A; exit $proc.exitcode

Set focus on TextBox in WPF from view model

An alternative approach based on @Sheridan answer here

 <TextBox Text="{Binding SomeText, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
                    <DataTrigger Binding="{Binding SomeTextIsFocused, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Value="True">
                        <Setter Property="FocusManager.FocusedElement" Value="{Binding RelativeSource={RelativeSource Self}}" />

In your view model set up your binding in the usual way and then set the SomeTextIsFocused to true to set the focus on your text box

Paramiko's SSHClient with SFTP


Sample Usage:

import paramiko

# Open a transport
host,port = "",22
transport = paramiko.Transport((host,port))

# Auth    
username,password = "bar","foo"

# Go!    
sftp = paramiko.SFTPClient.from_transport(transport)

# Download
filepath = "/etc/passwd"
localpath = "/home/remotepasswd"

# Upload
filepath = "/home/foo.jpg"
localpath = "/home/pony.jpg"

# Close
if sftp: sftp.close()
if transport: transport.close()

phpinfo() - is there an easy way for seeing it?

From the CLI the best way is to use grep like:

php -i | grep libxml

MySQL ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES)

I had similar problems because my password contains ";" char breaking my password when I creates it at first moment. Caution with this if can help you.

angular.js ng-repeat li items with html content

use ng-bind-html-unsafe

it will apply html with text inside like below:

    <li ng-repeat=" opt in opts" ng-bind-html-unsafe="opt.text" >
        {{ opt.text }}

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

Format datetime in mvc 4

Thanks Darin, For me, to be able to post to the create method, It only worked after I modified the BindModel code to :

public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    var displayFormat = bindingContext.ModelMetadata.DisplayFormatString;
    var value = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);

    if (!string.IsNullOrEmpty(displayFormat) && value != null)
        DateTime date;
        displayFormat = displayFormat.Replace("{0:", string.Empty).Replace("}", string.Empty);
        // use the format specified in the DisplayFormat attribute to parse the date
         if (DateTime.TryParse(value.AttemptedValue, CultureInfo.GetCultureInfo("en-GB"), DateTimeStyles.None, out date))
            return date;
                string.Format("{0} is an invalid date format", value.AttemptedValue)

    return base.BindModel(controllerContext, bindingContext);

Hope this could help someone else...

How to deserialize a JObject to .NET object

From the documentation I found this

JObject o = new JObject(
   new JProperty("Name", "John Smith"),
   new JProperty("BirthDate", new DateTime(1983, 3, 20))

JsonSerializer serializer = new JsonSerializer();
Person p = (Person)serializer.Deserialize(new JTokenReader(o), typeof(Person));


The class definition for Person should be compatible to the following:

class Person {
    public string Name { get; internal set; }
    public DateTime BirthDate { get; internal set; }


If you are using a recent version of and don't need custom serialization, please see TienDo's answer above (or below if you upvote me :P ), which is more concise.

How to detect when a youtube video finishes playing?

What you may want to do is include a script on all pages that does the following ... 1. find the youtube-iframe : searching for it by width and height by title or by finding in its source. You can do that by ... - looping through the window.frames by a for-in loop and then filter out by the properties

  1. inject jscript in the iframe of the current page adding the onYoutubePlayerReady must-include-function

  2. Add the event listeners etc..

Hope this helps

ECONNREFUSED error when connecting to mongodb from node.js

I had same problem. It was resolved by running same code in Administrator Console.

How to do if-else in Thymeleaf?

<div style="width:100%">
<span th:each="i : ${#numbers.sequence(1, 3)}">
<span th:if="${i == curpage}">
<a href="/listEmployee/${i}" class="btn btn-success custom-width" th:text="${i}"></a
<span th:unless="${i == curpage}">
<a href="/listEmployee/${i}" class="btn btn-danger custom-width" th:text="${i}"></a> 

enter image description here

How to find length of dictionary values

for i in range(0,len(d),1):
print i


What's the difference between isset() and array_key_exists()?

Answer to an old question as no answer here seem to address the 'warning' problem (explanation follows)

Basically, in this case of checking if a key exists in an array, isset

  • tells if the expression (array) is defined, and the key is set
  • no warning or error if the var is not defined, not an array ...
  • but returns false if the value for that key is null

and array_key_exists

  • tells if a key exists in an array as the name implies
  • but gives a warning if the array parameter is not an array

So how do we check if a key exists which value may be null in a variable

  • that may or may not be an array
  • (or similarly is a multidimensional array for which the key check happens at dim 2 and dim 1 value may not be an array for the 1st dim (etc...))

without getting a warning, without missing the existing key when its value is null (what were the PHP devs thinking would also be an interesting question, but certainly not relevant on SO). And of course we don't want to use @

isset($var[$key]);            // silent but misses null values
array_key_exists($key, $var); // works but warning if $var not defined/array

It seems is_array should be involved in the equation, but it gives a warning if $var is not defined, so that could be a solution:

if (isset($var[$key]) || 
    isset($var) && is_array($var) && array_key_exists($key, $var)) ...

which is likely to be faster if the tests are mainly on non-null values. Otherwise for an array with mostly null values

if (isset($var) && is_array($var) && array_key_exists($key, $var)) ...

will do the work.

Deploying just HTML, CSS webpage to Tomcat

Here's my setup: I am on Ubuntu 9.10.

Now, Here's what I did.

  1. Create a folder named "tomcat6-myapp" in /usr/share.
  2. Create a folder "myapp" under /usr/share/tomcat6-myapp.
  3. Copy the HTML file (that I need to deploy) to /usr/share/tomcat6-myapp/myapp. It must be named index.html.
  4. Go to /etc/tomcat6/Catalina/localhost.
  5. Create an xml file "myapp.xml" (i guess it must have the same name as the name of the folder in step 2) inside /etc/tomcat6/Catalina/localhost with the following contents.

    < Context path="/myapp" docBase="/usr/share/tomcat6-myapp/myapp" />
  6. This xml is called the 'Deployment Descriptor' which Tomcat reads and automatically deploys your app named "myapp".

  7. Now go to http://localhost:8080/myapp in your browser - the index.html gets picked up by tomcat and is shown.

I hope this helps!

Insert a new row into DataTable

// get the data table
DataTable dt = ...;

// generate the data you want to insert
DataRow toInsert = dt.NewRow();

// insert in the desired place
dt.Rows.InsertAt(toInsert, index);

Convert string to hex-string in C#

few Unicode alternatives

var s = "0";

var s1 = string.Concat(s.Select(c => $"{(int)c:x4}"));  // left padded with 0 - "0030d835dfcfd835dfdad835dfe5d835dff0d835dffb"

var sL = BitConverter.ToString(Encoding.Unicode.GetBytes(s)).Replace("-", "");       // Little Endian "300035D8CFDF35D8DADF35D8E5DF35D8F0DF35D8FBDF"
var sB = BitConverter.ToString(Encoding.BigEndianUnicode.GetBytes(s)).Replace("-", ""); // Big Endian "0030D835DFCFD835DFDAD835DFE5D835DFF0D835DFFB"

// no encodding "300035D8CFDF35D8DADF35D8E5DF35D8F0DF35D8FBDF"
byte[] b = new byte[s.Length * sizeof(char)];
Buffer.BlockCopy(s.ToCharArray(), 0, b, 0, b.Length);
var sb = BitConverter.ToString(b).Replace("-", "");

Non-resolvable parent POM for Could not find artifact and 'parent.relativePath' points at wrong local POM

We had the same issue.

The parent pom file was available in our local repository, but maven still unsuccessfully tried to download it from the central repository, or from the relativePath (there were no files in the relative path).

Turns out, there was a file called "_remote.repositories" in the local repository, which was causing this behavior. After deleting all the files with this name from the complete local repository, we could build our modules.

Raw_Input() Is Not Defined

For Python 3.x, use input(). For Python 2.x, use raw_input(). Don't forget you can add a prompt string in your input() call to create one less print statement. input("GUESS THAT NUMBER!").

Skip the headers when editing a csv file using Python

Another way of solving this is to use the DictReader class, which "skips" the header row and uses it to allowed named indexing.

Given "foo.csv" as follows:


Use DictReader like this:

import csv
with open('foo.csv') as f:
    reader = csv.DictReader(f, delimiter=',')
    for row in reader:
        print(row['FirstColumn'])  # Access by column header instead of column number

How to convert a string to a date in sybase

102 is the rule of thumb, convert (varchar, creat_tms, 102) > '2011'

How to change default language for SQL Server?

If you want to change MSSQL server language, you can use the following QUERY:

EXEC sp_configure 'default language', 'British English';

How can I pass command-line arguments to a Perl program?

Depends on what you want to do. If you want to use the two arguments as input files, you can just pass them in and then use <> to read their contents.

If they have a different meaning, you can use GetOpt::Std and GetOpt::Long to process them easily. GetOpt::Std supports only single-character switches and GetOpt::Long is much more flexible. From GetOpt::Long:

use Getopt::Long;
my $data   = "file.dat";
my $length = 24;
my $verbose;
$result = GetOptions ("length=i" => \$length,    # numeric
                    "file=s"   => \$data,      # string
                    "verbose"  => \$verbose);  # flag

Alternatively, @ARGV is a special variable that contains all the command line arguments. $ARGV[0] is the first (ie. "string1" in your case) and $ARGV[1] is the second argument. You don't need a special module to access @ARGV.

Increasing (or decreasing) the memory available to R processes

Microsoft Windows accepts any memory request from processes if it could be done.

There is no limit for the memory that can be provided to a process, except the Virtual Memory Size.

Virtual Memory Size is 4GB in 32bit systems for any processes, no matter how many applications you are running. Any processes can allocate up to 4GB memory in 32bit systems.

In practice, Windows automatically allocates some parts of allocated memory from RAM or page-file depending on processes requests and paging file mechanism.

But another limit is the size of paging file. If you have a small paging-file, you cannot allocated large memories. You could increase the size of paging file according to Microsoft to have more memory space.

What does [STAThread] do?

The STAThreadAttribute is essentially a requirement for the Windows message pump to communicate with COM components. Although core Windows Forms does not use COM, many components of the OS such as system dialogs do use this technology.

MSDN explains the reason in slightly more detail:

STAThreadAttribute indicates that the COM threading model for the application is single-threaded apartment. This attribute must be present on the entry point of any application that uses Windows Forms; if it is omitted, the Windows components might not work correctly. If the attribute is not present, the application uses the multithreaded apartment model, which is not supported for Windows Forms.

This blog post (Why is STAThread required?) also explains the requirement quite well. If you want a more in-depth view as to how the threading model works at the CLR level, see this MSDN Magazine article from June 2004 (Archived, Apr. 2009).

View stored procedure/function definition in MySQL

You can use table proc in database mysql:

mysql> SELECT body FROM mysql.proc
WHERE db = 'yourdb' AND name = 'procedurename' ;

Note that you must have a grant for select to mysql.proc:

mysql> GRANT SELECT ON mysql.proc TO 'youruser'@'yourhost' IDENTIFIED BY 'yourpass' ;

Edit a text file on the console using Powershell

Kinesics Text Editor.

It's super fast and handles large text files, though minimal in features. There's a GUI version and console version (k.exe) included. Should work the same on linux.

Example: In my test it took 7 seconds to open a 500mb disk image.


How to create a printable Twitter-Bootstrap page

To make print view look like tablet or desktop include bootstrap as .less, not as .css and then you can overwrite bootstrap responsive classes in the end of bootstrap_variables file for example like this:

@container-sm:      1200px;
@container-md:      1200px;
@container-lg:      1200px;
@screen-sm:         0;

Don't worry about putting this variables in the end of the file. LESS supports lazy loading of variables so they will be applied.

What is the difference between Visual Studio Express 2013 for Windows and Visual Studio Express 2013 for Windows Desktop?

A comparison between the different Visual Studio Express editions can be found at Visual Studio Express ( link). The difference between Windows and Windows Desktop is that with the Windows edition you can build Windows Store Apps (using .NET, WPF/XAML) while the Windows Desktop edition allows you to write classic Windows Desktop applications. It is possible to install both products on the same machine.

Visual Studio Express 2010 allows you to build Windows Desktop applications. Writing Windows Store applications is not possible with this product.

For learning I would suggest Notepad and the command line. While an IDE provides significant productivity enhancements to professionals, it can be intimidating to a beginner. If you want to use an IDE nevertheless I would recommend Visual Studio Express 2013 for Windows Desktop.

Update 2015-07-27: In addition to the Express Editions, Microsoft now offers Community Editions. These are still free for individual developers, open source contributors, and small teams. There are no Web, Windows, and Windows Desktop releases anymore either; the Community Edition can be used to develop any app type. In addition, the Community Edition does support (3rd party) Add-ins. The Community Edition offers the same functionality as the commercial Professional Edition.

Check that an email address is valid on iOS

Good cocoa function:

-(BOOL) NSStringIsValidEmail:(NSString *)checkString
   BOOL stricterFilter = NO; // Discussion
   NSString *stricterFilterString = @"^[A-Z0-9a-z\\._%+-]+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2,4}$";
   NSString *laxString = @"^.+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2}[A-Za-z]*$";
   NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
   NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
   return [emailTest evaluateWithObject:checkString];

Discussion on Lax vs. Strict -

And because categories are just better, you could also add an interface:

@interface NSString (emailValidation) 
  - (BOOL)isValidEmail;


@implementation NSString (emailValidation)
  BOOL stricterFilter = NO; // Discussion
  NSString *stricterFilterString = @"^[A-Z0-9a-z\\._%+-]+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2,4}$";
  NSString *laxString = @"^.+@([A-Za-z0-9-]+\\.)+[A-Za-z]{2}[A-Za-z]*$";
  NSString *emailRegex = stricterFilter ? stricterFilterString : laxString;
  NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
  return [emailTest evaluateWithObject:self];

And then utilize:

if([@"[email protected]" isValidEmail]) { /* True */ }
if([@"InvalidEmail@notreallyemailbecausenosuffix" isValidEmail]) { /* False */ }