Programs & Examples On #Cunit

Anything related to CUnit, a unit testing framework for C programs.

The entity type <type> is not part of the model for the current context

Could be stupid, but if you only got this error on some Table, dont forget to clean your project and rebuild (could save a lot of time)

When to use cla(), clf() or close() for clearing a plot in matplotlib?

They all do different things, since matplotlib uses a hierarchical order in which a figure window contains a figure which may consist of many axes. Additionally, there are functions from the pyplot interface and there are methods on the Figure class. I will discuss both cases below.

pyplot interface

pyplot is a module that collects a couple of functions that allow matplotlib to be used in a functional manner. I here assume that pyplot has been imported as import matplotlib.pyplot as plt. In this case, there are three different commands that remove stuff:

plt.cla() clears an axes, i.e. the currently active axes in the current figure. It leaves the other axes untouched.

plt.clf() clears the entire current figure with all its axes, but leaves the window opened, such that it may be reused for other plots.

plt.close() closes a window, which will be the current window, if not specified otherwise.

Which functions suits you best depends thus on your use-case.

The close() function furthermore allows one to specify which window should be closed. The argument can either be a number or name given to a window when it was created using figure(number_or_name) or it can be a figure instance fig obtained, i.e., usingfig = figure(). If no argument is given to close(), the currently active window will be closed. Furthermore, there is the syntax close('all'), which closes all figures.

methods of the Figure class

Additionally, the Figure class provides methods for clearing figures. I'll assume in the following that fig is an instance of a Figure:

fig.clf() clears the entire figure. This call is equivalent to plt.clf() only if fig is the current figure.

fig.clear() is a synonym for fig.clf()

Note that even del fig will not close the associated figure window. As far as I know the only way to close a figure window is using plt.close(fig) as described above.

Image overlay on responsive sized images bootstrap

<div class="col-md-4 py-3 pic-card">
          <div class="card ">
          <div class="pic-overlay"></div>
          <img class="img-fluid " src="images/Site Images/Health & Fitness-01.png" alt="">
          <div class="centeredcard">
              <span class="card-headings">HEALTH & FITNESS</span>
            <div class="content-inner mt-5">
              <p class="lead  p-overlay">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Recusandae ipsam nemo quasi quo quae voluptate.</p>

     position: relative;


    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    position: absolute;
    transition: background-color 0.5s ease;

    position: relative;
     display: none;

        background-color: $dark-overlay;


         display: block;
         cursor: pointer;

        font-size: 15px;
        padding: 0;

        content: '';
        width: 80%;
        border-bottom: solid 2px  rgb(52, 178, 179);
        position: absolute;
        left: 5%;
        top: 25%;
        z-index: 1;
         font-size: 15px;

enter code here

How to detect window.print() finish

It is difficult, due to different browser behavior after print. Desktop Chrome handles the print dialogue internally, so doesn't shift focus after print, however, afterprint event works fine here (As of now, 81.0). On the other hand, Chrome on mobile device and most of the other browsers shifts focus after print and afterprint event doesn't work consistently here. Mouse movement event doesn't work on mobile devices.

So, Detect if it is Desktop Chrome, If Yes, use afterprint event. If No, use focus based detection. You can also use mouse movement event(Works in desktop only) in combination of these, to cover more browsers and more scenarios.

Where is database .bak file saved from SQL Server Management Studio?

have you tried:

C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\Backup

Script to get all backups in the last week can be found at:

I have plenty more backup SQL scripts there also at

How to hide the keyboard when I press return key in a UITextField?

In swift do like this:
First in your ViewController implement this UITextFieldDelegate For eg.

class MyViewController: UIViewController, UITextFieldDelegate {

Now add a delegate to a TextField in which you want to dismiss the keyboard when return is tapped either in viewDidLoad method like below or where you are initializing it. For eg.

override func viewDidLoad() {

    myTextField.delegate = self

Now add this method.

func textFieldShouldReturn(textField: UITextField) -> Bool {

    return true

How to create an HTML button that acts like a link?

If it's the visual appearance of a button you're looking for in a basic HTML anchor tag then you can use the Twitter Bootstrap framework to format any of the following common HTML type links/buttons to appear as a button. Please note the visual differences between version 2, 3 or 4 of the framework:

<a class="btn" href="">Link</a>
<button class="btn" type="submit">Button</button>
<input class="btn" type="button" value="Input">
<input class="btn" type="submit" value="Submit">

Bootstrap (v4) sample appearance:

Sample output of Boostrap v4 buttons

Bootstrap (v3) sample appearance:

Sample output of Boostrap v3 buttons

Bootstrap (v2) sample appearance:

Sample output of Boostrap v2 buttons

Comparing two java.util.Dates to see if they are in the same day

you can apply the same logic as the SimpleDateFormat solution without relying on SimpleDateFormat

date1.getFullYear()*10000 + date1.getMonth()*100 + date1.getDate() == 
date2.getFullYear()*10000 + date2.getMonth()*100 + date2.getDate()

How does autowiring work in Spring?

Spring dependency inject help you to remove coupling from your classes. Instead of creating object like this:

UserService userService = new UserServiceImpl();

You will be using this after introducing DI:

private UserService userService;

For achieving this you need to create a bean of your service in your ServiceConfiguration file. After that you need to import that ServiceConfiguration class to your WebApplicationConfiguration class so that you can autowire that bean into your Controller like this:

public class AccController {

    private UserService userService;

You can find a java configuration based POC here example.

Disable validation of HTML5 form elements

Here is the function I use to prevent chrome and opera from showing the invalid input dialog even when using novalidate.

window.submittingForm = false;
$('input[novalidate]').bind('invalid', function(e) {
        window.submittingForm = true;
        setTimeout(function(){window.submittingForm = false;}, 100);
    return false;

org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing

Instead of passing reference object passed the saved object, below is explanation which solve my issue:


Role savedEntity= entityManager.persist(role);

How to use JNDI DataSource provided by Tomcat in Spring?

Documentation: C.2.3.1 <jee:jndi-lookup/> (simple)


<jee:jndi-lookup id="dataSource" jndi-name="jdbc/MyDataSource"/>

You just need to find out what JNDI name your appserver has bound the datasource to. This is entirely server-specific, consult the docs on your server to find out how.

Remember to declare the jee namespace at the top of your beans file, as described in C.2.3 The jee schema.

How to execute shell command in Javascript

With nashorn you can write a script like this:

$EXEC('find -type f');
var files = $OUT.split('\n');

and run it:

jjs -scripting each_file.js

Trigger css hover with JS

I don't think what your asking is possible.

See: Hover Item with JQuery

Basically, adding a class is the only way to accomplish this that I am aware of.

How to get GET (query string) variables in Express.js on Node.js?

I learned from the other answers and decided to use this code throughout my site:

var query = require('url').parse(req.url,true).query;

Then you can just call

var id =;
var option = query.option;

where the URL for get should be


Unit Testing C Code

First, look here:

My company has a C library our customers use. We use CxxTest (a C++ unit test library) to test the code. CppUnit will also work. If you're stuck in C, I'd recommend RCUNIT (but CUnit is good too).

How to test code dependent on environment variables using JUnit?

Decouple the Java code from the Environment variable providing a more abstract variable reader that you realize with an EnvironmentVariableReader your code to test reads from.

Then in your test you can give an different implementation of the variable reader that provides your test values.

Dependency injection can help in this.

nodeJS - How to create and read session with express

I need to point out here that you're incorrectly adding middleware to the application. The app.use calls should not be done within the app.get request handler, but outside of it. Simply call them directly after createServer, or take a look at the other examples in the docs.

The secret you pass to express.session should be a string constant, or perhaps something taken from a configuration file. Don't feed it something the client might know, that's actually dangerous. It's a secret only the server should know about.

If you want to store the email address in the session, simply do something along the lines of: = req.param('email');

With that out of the way...

If I understand correctly, what you're trying to do is handle one or more HTTP requests and keep track of a session, then later on open a Socket.IO connection from which you need the session data as well.

What's tricky about this problem is that Socket.IO's means of making the magic work on any http.Server is by hijacking the request event. Thus, Express' (or rather Connect's) session middleware is never called on the Socket.IO connection.

I believe you can make this work, though, with some trickery.

You can get to Connect's session data; you simply need to get a reference to the session store. The easiest way to do that is to create the store yourself before calling express.session:

// A MemoryStore is the default, but you probably want something
// more robust for production use.
var store = new express.session.MemoryStore;
app.use(express.session({ secret: 'whatever', store: store }));

Every session store has a get(sid, callback) method. The sid parameter, or session ID, is stored in a cookie on the client. The default name of that cookie is connect.sid. (But you can give it any name by specifying a key option in your express.session call.)

Then, you need to access that cookie on the Socket.IO connection. Unfortunately, Socket.IO doesn't seem to give you access to the http.ServerRequest. A simple work around would be to fetch the cookie in the browser, and send it over the Socket.IO connection.

Code on the server would then look something like the following:

var io      = require(''),
    express = require('express');

var app    = express.createServer(),
    socket = io.listen(app),
    store  = new express.session.MemoryStore;
app.use(express.session({ secret: 'something', store: store }));

app.get('/', function(req, res) {
  var old =; = req.param('email');

  res.header('Content-Type', 'text/plain');
  res.send("Email was '" + old + "', now is '" + + "'.");

socket.on('connection', function(client) {
  // We declare that the first message contains the SID.
  // This is where we handle the first message.
  client.once('message', function(sid) {
    store.get(sid, function(err, session) {
      if (err || !session) {
        // Do some error handling, bail.

      // Any messages following are your chat messages.
      client.on('message', function(message) {
        if ( === {


This assumes you only want to read an existing session. You cannot actually create or delete sessions, because Socket.IO connections may not have a HTTP response to send the Set-Cookie header in (think WebSockets).

If you want to edit sessions, that may work with some session stores. A CookieStore wouldn't work for example, because it also needs to send a Set-Cookie header, which it can't. But for other stores, you could try calling the set(sid, data, callback) method and see what happens.

How do I set up Visual Studio Code to compile C++ code?

A makefile task example for new 2.0.0 tasks.json version.

In the snippet below some comments I hope they will be useful.

    "version": "2.0.0",
    "tasks": [
            "label": "<TASK_NAME>",
            "type": "shell",
            "command": "make",
            // use options.cwd property if the Makefile is not in the project root ${workspaceRoot} dir
            "options": {
                "cwd": "${workspaceRoot}/<DIR_WITH_MAKEFILE>"
            // start the build without prompting for task selection, use "group": "build" otherwise
            "group": {
                "kind": "build",
                "isDefault": true
            "presentation": {
                "echo": true,
                "reveal": "always",
                "focus": false,
                "panel": "shared"
            // arg passing example: in this case is executed make QUIET=0
            "args": ["QUIET=0"],
            // Use the standard less compilation problem matcher.
            "problemMatcher": {
                "owner": "cpp",
                "fileLocation": ["absolute"],
                "pattern": {
                    "regexp": "^(.*):(\\d+):(\\d+):\\s+(warning|error):\\s+(.*)$",
                    "file": 1,
                    "line": 2,
                    "column": 3,
                    "severity": 4,
                    "message": 5

How to remove commits from a pull request

You have several techniques to do it.

This post - read the part about the revert will explain in details what we want to do and how to do it.

Here is the most simple solution to your problem:

# Checkout the desired branch
git checkout <branch>

# Undo the desired commit
git revert <commit>

# Update the remote with the undo of the code
git push origin <branch>

The revert command will create a new commit with the undo of the original commit.

Remove #N/A in vlookup result

if you are looking to change the colour of the cell in case of vlookup error then go for conditional formatting . To do this go the "CONDITIONAL FORMATTING" > "NEW RULE". In this choose the "Select the rule type" = "Format only cells that contains" . After this the window below changes , in which choose "Error" in the first drop-down .After this proceed accordingly.

Http 415 Unsupported Media type error with JSON

If you are making jquery ajax request, dont forget to add


How do you execute an arbitrary native command from a string?

The accepted answer wasn't working for me when trying to parse the registry for uninstall strings, and execute them. Turns out I didn't need the call to Invoke-Expression after all.

I finally came across this nice template for seeing how to execute uninstall strings:

$path = 'HKLM:\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall'
$app = 'MyApp'
$apps= @{}
Get-ChildItem $path | 
    Where-Object -FilterScript {$_.getvalue('DisplayName') -like $app} | 
    ForEach-Object -process {$apps.Set_Item(

foreach ($uninstall_string in $apps.GetEnumerator()) {
    $uninstall_app, $uninstall_arg = $' ')
    & $uninstall_app $uninstall_arg

This works for me, namely because $app is an in house application that I know will only have two arguments. For more complex uninstall strings you may want to use the join operator. Also, I just used a hash-map, but really, you'd probably want to use an array.

Also, if you do have multiple versions of the same application installed, this uninstaller will cycle through them all at once, which confuses MsiExec.exe, so there's that too.

angular 4: *ngIf with multiple conditions

<div *ngIf="currentStatus !== ('status1' || 'status2' || 'status3' || 'status4')">

Prevent RequireJS from Caching Required Scripts

In production

urlArgs can cause problems!

The principal author of requirejs prefers not to use urlArgs:

For deployed assets, I prefer to put the version or hash for the whole build as a build directory, then just modify the baseUrl config used for the project to use that versioned directory as the baseUrl. Then no other files change, and it helps avoid some proxy issues where they may not cache an URL with a query string on it.

[Styling mine.]

I follow this advice.

In development

I prefer to use a server that intelligently caches files that may change frequently: a server that emits Last-Modified and responds to If-Modified-Since with 304 when appropriate. Even a server based on Node's express set to serve static files does this right out the box. It does not require doing anything to my browser, and does not mess up breakpoints.

How to disable GCC warnings for a few lines of code

Rather than silencing the warnings, gcc style is usually to use either standard C constructs or the __attribute__ extension to tell the compiler more about your intention. For instance, the warning about assignment used as a condition is suppressed by putting the assignment in parentheses, i.e. if ((p=malloc(cnt))) instead of if (p=malloc(cnt)). Warnings about unused function arguments can be suppressed by some odd __attribute__ I can never remember, or by self-assignment, etc. But generally I prefer just globally disabling any warning option that generates warnings for things that will occur in correct code.

Android: Tabs at the BOTTOM

Not sure if it will work for all versions of Android (especially those with custom UI stuff), but I was able to remove the gray bar at the bottom by adding


to the TabWidget XML...

how to bold words within a paragraph in HTML/CSS?

Add <b> tag

<p> <b> I am in Bold </b></p>

For more text formatting tags click here

PHP How to fix Notice: Undefined variable:

Declare them before the while loop.

$hn = "";
$pid = "";
$datereg = "";
$prefix = "";
$fname = "";
$lname = "";
$age = "";
$sex = "";

You are getting the notice because the variables are declared and assigned inside the loop.

IOException: read failed, socket might closed - Bluetooth on Android 4.3

Even i had the same problem ,finally understand my issue , i was trying to connect from (out of range) Bluetooth coverage range.

Android : change button text and background color

Just use a MaterialButton and the app:backgroundTint and android:textColor attributes:


Why is it common to put CSRF prevention tokens in cookies?

Besides the session cookie (which is kind of standard), I don't want to use extra cookies.

I found a solution which works for me when building a Single Page Web Application (SPA), with many AJAX requests. Note: I am using server side Java and client side JQuery, but no magic things so I think this principle can be implemented in all popular programming languages.

My solution without extra cookies is simple:

Client Side

Store the CSRF token which is returned by the server after a succesful login in a global variable (if you want to use web storage instead of a global thats fine of course). Instruct JQuery to supply a X-CSRF-TOKEN header in each AJAX call.

The main "index" page contains this JavaScript snippet:

// Intialize global variable CSRF_TOKEN to empty sting. 
// This variable is set after a succesful login
window.CSRF_TOKEN = '';

// the supplied callback to .ajaxSend() is called before an Ajax request is sent
$( document ).ajaxSend( function( event, jqXHR ) {
    jqXHR.setRequestHeader('X-CSRF-TOKEN', window.CSRF_TOKEN);

Server Side

On successul login, create a random (and long enough) CSRF token, store this in the server side session and return it to the client. Filter certain (sensitive) incoming requests by comparing the X-CSRF-TOKEN header value to the value stored in the session: these should match.

Sensitive AJAX calls (POST form-data and GET JSON-data), and the server side filter catching them, are under a /dataservice/* path. Login requests must not hit the filter, so these are on another path. Requests for HTML, CSS, JS and image resources are also not on the /dataservice/* path, thus not filtered. These contain nothing secret and can do no harm, so this is fine.

@WebFilter(urlPatterns = {"/dataservice/*"})
String sessionCSRFToken = req.getSession().getAttribute("CSRFToken") != null ? (String) req.getSession().getAttribute("CSRFToken") : null;
if (sessionCSRFToken == null || req.getHeader("X-CSRF-TOKEN") == null || !req.getHeader("X-CSRF-TOKEN").equals(sessionCSRFToken)) {
} else
    chain.doFilter(request, response);

In C# check that filename is *possibly* valid (not that it exists)

Try out this method which would try to cover for all the possible Exceptions scenarios. It would work for almost all the Windows related Paths.

/// <summary>
/// Validate the Path. If path is relative append the path to the project directory by default.
/// </summary>
/// <param name="path">Path to validate</param>
/// <param name="RelativePath">Relative path</param>
/// <param name="Extension">If want to check for File Path</param>
/// <returns></returns>
private static bool ValidateDllPath(ref string path, string RelativePath = "", string Extension = "") {
    // Check if it contains any Invalid Characters.
    if (path.IndexOfAny(Path.GetInvalidPathChars()) == -1) {
        try {
            // If path is relative take %IGXLROOT% as the base directory
            if (!Path.IsPathRooted(path)) {
                if (string.IsNullOrEmpty(RelativePath)) {
                    // Exceptions handled by Path.GetFullPath
                    // ArgumentException path is a zero-length string, contains only white space, or contains one or more of the invalid characters defined in GetInvalidPathChars. -or- The system could not retrieve the absolute path.
                    // SecurityException The caller does not have the required permissions.
                    // ArgumentNullException path is null.
                    // NotSupportedException path contains a colon (":") that is not part of a volume identifier (for example, "c:\"). 
                    // PathTooLongException The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.

                    // RelativePath is not passed so we would take the project path 
                    path = Path.GetFullPath(RelativePath);

                } else {
                    // Make sure the path is relative to the RelativePath and not our project directory
                    path = Path.Combine(RelativePath, path);

            // Exceptions from FileInfo Constructor:
            //   System.ArgumentNullException:
            //     fileName is null.
            //   System.Security.SecurityException:
            //     The caller does not have the required permission.
            //   System.ArgumentException:
            //     The file name is empty, contains only white spaces, or contains invalid characters.
            //   System.IO.PathTooLongException:
            //     The specified path, file name, or both exceed the system-defined maximum
            //     length. For example, on Windows-based platforms, paths must be less than
            //     248 characters, and file names must be less than 260 characters.
            //   System.NotSupportedException:
            //     fileName contains a colon (:) in the middle of the string.
            FileInfo fileInfo = new FileInfo(path);

            // Exceptions using FileInfo.Length:
            //   System.IO.IOException:
            //     System.IO.FileSystemInfo.Refresh() cannot update the state of the file or
            //     directory.
            //   System.IO.FileNotFoundException:
            //     The file does not exist.-or- The Length property is called for a directory.
            bool throwEx = fileInfo.Length == -1;

            // Exceptions using FileInfo.IsReadOnly:
            //   System.UnauthorizedAccessException:
            //     Access to fileName is denied.
            //     The file described by the current System.IO.FileInfo object is read-only.-or-
            //     This operation is not supported on the current platform.-or- The caller does
            //     not have the required permission.
            throwEx = fileInfo.IsReadOnly;

            if (!string.IsNullOrEmpty(Extension)) {
                // Validate the Extension of the file.
                if (Path.GetExtension(path).Equals(Extension, StringComparison.InvariantCultureIgnoreCase)) {
                    // Trim the Library Path
                    path = path.Trim();
                    return true;
                } else {
                    return false;
            } else {
                return true;

        } catch (ArgumentNullException) {
            //   System.ArgumentNullException:
            //     fileName is null.
        } catch (System.Security.SecurityException) {
            //   System.Security.SecurityException:
            //     The caller does not have the required permission.
        } catch (ArgumentException) {
            //   System.ArgumentException:
            //     The file name is empty, contains only white spaces, or contains invalid characters.
        } catch (UnauthorizedAccessException) {
            //   System.UnauthorizedAccessException:
            //     Access to fileName is denied.
        } catch (PathTooLongException) {
            //   System.IO.PathTooLongException:
            //     The specified path, file name, or both exceed the system-defined maximum
            //     length. For example, on Windows-based platforms, paths must be less than
            //     248 characters, and file names must be less than 260 characters.
        } catch (NotSupportedException) {
            //   System.NotSupportedException:
            //     fileName contains a colon (:) in the middle of the string.
        } catch (FileNotFoundException) {
            // System.FileNotFoundException
            //  The exception that is thrown when an attempt to access a file that does not
            //  exist on disk fails.
        } catch (IOException) {
            //   System.IO.IOException:
            //     An I/O error occurred while opening the file.
        } catch (Exception) {
            // Unknown Exception. Might be due to wrong case or nulll checks.
    } else {
        // Path contains invalid characters
    return false;

How are iloc and loc different?

iloc works based on integer positioning. So no matter what your row labels are, you can always, e.g., get the first row by doing


or the last five rows by doing


You can also use it on the columns. This retrieves the 3rd column:

df.iloc[:, 2]    # the : in the first position indicates all rows

You can combine them to get intersections of rows and columns:

df.iloc[:3, :3] # The upper-left 3 X 3 entries (assuming df has 3+ rows and columns)

On the other hand, .loc use named indices. Let's set up a data frame with strings as row and column labels:

df = pd.DataFrame(index=['a', 'b', 'c'], columns=['time', 'date', 'name'])

Then we can get the first row by

df.loc['a']     # equivalent to df.iloc[0]

and the second two rows of the 'date' column by

df.loc['b':, 'date']   # equivalent to df.iloc[1:, 1]

and so on. Now, it's probably worth pointing out that the default row and column indices for a DataFrame are integers from 0 and in this case iloc and loc would work in the same way. This is why your three examples are equivalent. If you had a non-numeric index such as strings or datetimes, df.loc[:5] would raise an error.

Also, you can do column retrieval just by using the data frame's __getitem__:

df['time']    # equivalent to df.loc[:, 'time']

Now suppose you want to mix position and named indexing, that is, indexing using names on rows and positions on columns (to clarify, I mean select from our data frame, rather than creating a data frame with strings in the row index and integers in the column index). This is where .ix comes in:

df.ix[:2, 'time']    # the first two rows of the 'time' column

I think it's also worth mentioning that you can pass boolean vectors to the loc method as well. For example:

 b = [True, False, True]

Will return the 1st and 3rd rows of df. This is equivalent to df[b] for selection, but it can also be used for assigning via boolean vectors:

df.loc[b, 'name'] = 'Mary', 'John'

Parsing JSON from XmlHttpRequest.responseJSON

Note: I've only tested this in Chrome.

it adds a prototype function to the XMLHttpRequest .. XHR2,

in XHR 1 you probably just need to replace this.response with this.responseText

 return JSON.parse(this.response);

to return the json in xhr2



If you plan to use XHR with arraybuffer or other response types then you have to check if the response is a string.

in any case you have to add more checks e.g. if it's not able to parse the json.

 return (typeof this.response==='string'?JSON.parse(this.response):this.response);

Replace and overwrite instead of appending

Using python3 pathlib library:

import re
from pathlib import Path
import shutil

shutil.copy2("/tmp/test.xml", "/tmp/test.xml.bak") # create backup
filepath = Path("/tmp/test.xml")
content = filepath.read_text()
filepath.write_text(re.sub(r"<string>ABC</string>(\s+)<string>(.*)</string>",r"<xyz>ABC</xyz>\1<xyz>\2</xyz>", content))

Similar method using different approach to backups:

from pathlib import Path

filepath = Path("/tmp/test.xml")
filepath.rename(filepath.with_suffix('.bak')) # different approach to backups
content = filepath.read_text()
filepath.write_text(re.sub(r"<string>ABC</string>(\s+)<string>(.*)</string>",r"<xyz>ABC</xyz>\1<xyz>\2</xyz>", content))

Can one class extend two classes?

No you cannot make a class extend to two classes.

A possible solution is to make it extend from another class, and make that class extend from another again.

How to use matplotlib tight layout with Figure?

Just call fig.tight_layout() as you normally would. (pyplot is just a convenience wrapper. In most cases, you only use it to quickly generate figure and axes objects and then call their methods directly.)

There shouldn't be a difference between the QtAgg backend and the default backend (or if there is, it's a bug).


import matplotlib.pyplot as plt

#-- In your case, you'd do something more like:
# from matplotlib.figure import Figure
# fig = Figure()
#-- ...but we want to use it interactive for a quick example, so 
#--    we'll do it this way
fig, axes = plt.subplots(nrows=4, ncols=4)

for i, ax in enumerate(axes.flat, start=1):
    ax.set_title('Test Axes {}'.format(i))
    ax.set_xlabel('X axis')
    ax.set_ylabel('Y axis')

Before Tight Layout

enter image description here

After Tight Layout

import matplotlib.pyplot as plt

fig, axes = plt.subplots(nrows=4, ncols=4)

for i, ax in enumerate(axes.flat, start=1):
    ax.set_title('Test Axes {}'.format(i))
    ax.set_xlabel('X axis')
    ax.set_ylabel('Y axis')


enter image description here

Adding Counter in shell script

You may do this with a for loop instead of a while:

for ((count = 0; count < max_loop; count++)); do
  if /home/hadoop/latest/bin/hadoop fs -ls /apps/hdtech/bds/quality-rt/dt=$DATE_YEST_FORMAT2 then
       echo "Files Present" | mailx -s "File Present"  -r [email protected] [email protected]
       echo "Sleeping for half an hour" | mailx -s "Time to Sleep Now"  -r [email protected] [email protected]
       sleep 1800

if [ "$count" -eq "$max_loop" ]; then
  echo "Maximum number of trials reached" >&2
  exit 1

Press Keyboard keys using a batch file

Wow! Mean this that you must learn a different programming language just to send two keys to the keyboard? There are simpler ways for you to achieve the same thing. :-)

The Batch file below is an example that start another program (cmd.exe in this case), send a command to it and then send an Up Arrow key, that cause to recover the last executed command. The Batch file is simple enough to be understand with no problems, so you may modify it to fit your needs.

@if (@CodeSection == @Batch) @then

@echo off

rem Use %SendKeys% to send keys to the keyboard buffer
set SendKeys=CScript //nologo //E:JScript "%~F0"

rem Start the other program in the same Window
start "" /B cmd

%SendKeys% "echo off{ENTER}"

set /P "=Wait and send a command: " < NUL
ping -n 5 -w 1 > NUL
%SendKeys% "echo Hello, world!{ENTER}"

set /P "=Wait and send an Up Arrow key: [" < NUL
ping -n 5 -w 1 > NUL
%SendKeys% "{UP}"

set /P "=] Wait and send an Enter key:" < NUL
ping -n 5 -w 1 > NUL
%SendKeys% "{ENTER}"

%SendKeys% "exit{ENTER}"

goto :EOF


// JScript section

var WshShell = WScript.CreateObject("WScript.Shell");

For a list of key names for SendKeys, see:

For example:


For a further explanation of this solution, see: GnuWin32 openssl s_client conn to WebSphere MQ server not closing at EOF, hangs

Convert nullable bool? to bool

System.Convert works fine by me.

using System; ... Bool fixed = Convert.ToBoolean(NullableBool);

Stop/Close webcam stream which is opened by navigator.mediaDevices.getUserMedia

Starting Webcam Video with different browsers

For Opera 12

window.navigator.getUserMedia(param, function(stream) {
                            video.src =window.URL.createObjectURL(stream);
                        }, videoError );

For Firefox Nightly 18.0

window.navigator.mozGetUserMedia(param, function(stream) {
                            video.mozSrcObject = stream;
                        }, videoError );

For Chrome 22

window.navigator.webkitGetUserMedia(param, function(stream) {
                            video.src =window.webkitURL.createObjectURL(stream);
                        },  videoError );

Stopping Webcam Video with different browsers

For Opera 12


For Firefox Nightly 18.0


For Chrome 22


With this the Webcam light go down everytime...

How to get ID of button user just clicked?

You can also try this simple one-liner code. Just call the alert method on onclick attribute.

<button id="some_id1" onclick="alert("></button>

HtmlEncode from Class Library

Just reference the System.Web assembly and then call: HttpServerUtility.HtmlEncode

PHP regular expression - filter number only

You can try that one:

$string = preg_replace('/[^0-9]/', '', $string);


What's the best visual merge tool for Git?

If you are just looking for a diff tool beyond compare is pretty nice:

Python; urllib error: AttributeError: 'bytes' object has no attribute 'read'

I got the same error {AttributeError: 'bytes' object has no attribute 'read'} in python3. This worked for me later without using json:

from urllib.request import urlopen
from bs4 import BeautifulSoup

url = 'https://someurl/'
page = urlopen(url)
html =
soup = BeautifulSoup(html)

Getting random numbers in Java

int max = 50;
int min = 1;

1. Using Math.random()

double random = Math.random() * 49 + 1;
int random = (int )(Math.random() * 50 + 1);

This will give you value from 1 to 50 in case of int or 1.0 (inclusive) to 50.0 (exclusive) in case of double


random() method returns a random number between 0.0 and 0.9..., you multiply it by 50, so upper limit becomes 0.0 to 49.999... when you add 1, it becomes 1.0 to 50.999..., now when you truncate to int, you get 1 to 50. (thanks to @rup in comments). leepoint's awesome write-up on both the approaches.

2. Using Random class in Java.

Random rand = new Random(); 
int value = rand.nextInt(50); 

This will give value from 0 to 49.

For 1 to 50: rand.nextInt((max - min) + 1) + min;

Source of some Java Random awesomeness.

How to make bootstrap 3 fluid layout without horizontal scrollbar

You can add a 10px padding on the sides to your body element if all it's children are rows

body {
  padding: 0 10px;

if your HTML markup looks something like this:

    <div class="row"></div>
    <div class="row"></div>
    <div class="row"></div>

The rows have a 10 px negative margin. That's what's causing the overflow. If you add 10px padding to the body, they will cancel each other out.

How to write UPDATE SQL with Table alias in SQL Server 2008?

The syntax for using an alias in an update statement on SQL Server is as follows:

WHERE Q.ID = 101;

The alias should not be necessary here though.

How I can filter a Datatable?

If you're using at least .NET 3.5, i would suggest to use Linq-To-DataTable instead since it's much more readable and powerful:

DataTable tblFiltered = table.AsEnumerable()
          .Where(row => row.Field<String>("Nachname") == username
                   &&   row.Field<String>("Ort") == location)
          .OrderByDescending(row => row.Field<String>("Nachname"))

Above code is just an example, actually you have many more methods available.

Remember to add using System.Linq; and for the AsEnumerable extension method a reference to the System.Data.DataSetExtensions dll (How).

Embed website into my site

**What's the best way to avoid a fixed size, i.e., to have the embedded website scale responsively to the browser's window size? I'd like to avoid scroll bars within my website. – CGFoX Feb 2 '19 at 15:52

**Is it possible to set width and height to percentages instead of absolute pixels? – CGFoX Mar 16 at 11:53

ANSWER: <embed src="" style="width:100%; height: 50vw;">

Adding new line of data to TextBox

Because you haven't specified what front end (GUI technology) you're using it would be hard to make a specific recommendation. In WPF you could create a listbox and for each new line of chat add a new listboxitem to the end of the collection. This link provides some suggestions as to how you may achieve the same result in a winforms environment.

Avoid trailing zeroes in printf()

What about something like this (might have rounding errors and negative-value issues that need debugging, left as an exercise for the reader):

printf("%.0d%.4g\n", (int)f/10, f-((int)f-(int)f%10));

It's slightly programmatic but at least it doesn't make you do any string manipulation.

Most recent previous business day in Python

Use pandas!

import datetime
# BDay is business day, not birthday...
from pandas.tseries.offsets import BDay

today =
print(today - BDay(4))

Since today is Thursday, Sept 26, that will give you an output of:

datetime.datetime(2013, 9, 20, 14, 8, 4, 89761)

Bootstrap table without stripe / borders

Install bootstrap either with npm or cdn link

<table class="table table-borderless">
  <th scope="col">#</th>
  <th scope="col">First</th>
  <th scope="col">Last</th>
  <th scope="col">Handle</th>
  <th scope="row">1</th>
  <th scope="row">2</th>
  <th scope="row">3</th>
    <td colspan="2">Larry the Bird</td>

get the reference with this link

Can I scroll a ScrollView programmatically in Android?

I had to create Interface

public interface ScrollViewListener {
    void onScrollChanged(ScrollViewExt scrollView, 
                         int x, int y, int oldx, int oldy);

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ScrollView;

public class CustomScrollView extends ScrollView {
    private ScrollViewListener scrollViewListener = null;
    public ScrollViewExt(Context context) {

    public CustomScrollView (Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

    public CustomScrollView (Context context, AttributeSet attrs) {
        super(context, attrs);

    public void setScrollViewListener(ScrollViewListener scrollViewListener) {
        this.scrollViewListener = scrollViewListener;

    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        if (scrollViewListener != null) {
            scrollViewListener.onScrollChanged(this, l, t, oldl, oldt);

<"Your Package name ".CustomScrollView 

    private CustomScrollView scrollView;

scrollView = (CustomScrollView)mView.findViewById(;

    public void onScrollChanged(ScrollViewExt scrollView, int x, int y, int oldx, int oldy) {
        // We take the last son in the scrollview
        View view = (View) scrollView.getChildAt(scrollView.getChildCount() - 1);
        int diff = (view.getBottom() - (scrollView.getHeight() + scrollView.getScrollY()));

        // if diff is zero, then the bottom has been reached
        if (diff == 0) {
                // do stuff
            //TODO keshav gers


Write lines of text to a file in R

You could do that in a single statement


How to write one new line in Bitbucket markdown?

Feb 3rd 2020:

  • Atlassian Bitbucket v5.8.3 local installation.
  • I wanted to add a new line around an horizontal line. --- did produce the line, but I could not get new lines to work with suggestions above.
  • note: I did not want to use the [space][space] suggestion, since my editor removes trailing spaces on save, and I like this feature on.

I ended up doing this:


Resulting in:

----------------- AN HORIZONTAL LINE ----------------

What is a regular expression for a MAC Address?

delimiter: ":","-","."

double or single: 00 = 0, 0f = f




exm: 00:27:0e:2a:b9:aa, 00-27-0E-2A-B9-AA, 0.27.e.2a.b9.aa ...

Copy file remotely with PowerShell

Use net use or New-PSDrive to create a new drive:

New-PsDrive: create a new PsDrive only visible in PowerShell environment:

New-PSDrive -Name Y -PSProvider filesystem -Root \\ServerName\Share
Copy-Item BigFile Y:\BigFileCopy

Net use: create a new drive visible in all parts of the OS.

Net use y: \\ServerName\Share
Copy-Item BigFile Y:\BigFileCopy

How to read user input into a variable in Bash?

Try this


read -p "Enter a word: " word
echo "You entered $word"

What's the @ in front of a string in C#?

Since you explicitly asked for VB as well, let me just add that this verbatim string syntax doesn't exist in VB, only in C#. Rather, all strings are verbatim in VB (except for the fact that they cannot contain line breaks, unlike C# verbatim strings):

Dim path = "C:\My\Path"
Dim message = "She said, ""Hello, beautiful world."""

Escape sequences don't exist in VB (except for the doubling of the quote character, like in C# verbatim strings) which makes a few things more complicated. For example, to write the following code in VB you need to use concatenation (or any of the other ways to construct a string)

string x = "Foo\nbar";

In VB this would be written as follows:

Dim x = "Foo" & Environment.NewLine & "bar"

(& is the VB string concatenation operator. + could equally be used.)

Why do I get "Pickle - EOFError: Ran out of input" reading an empty file?

As you see, that's actually a natural error ..

A typical construct for reading from an Unpickler object would be like this ..

    data = unpickler.load()
except EOFError:
    data = list()  # or whatever you want

EOFError is simply raised, because it was reading an empty file, it just meant End of File ..

Return 0 if field is null in MySQL

Yes IFNULL function will be working to achieve your desired result.

SELECT uo.order_id, uo.order_total, uo.order_status,
        (SELECT IFNULL(SUM(uop.price * uop.qty),0) 
         FROM uc_order_products uop 
         WHERE uo.order_id = uop.order_id
        ) AS products_subtotal,
        (SELECT IFNULL(SUM(upr.amount),0) 
         FROM uc_payment_receipts upr 
         WHERE uo.order_id = upr.order_id
        ) AS payment_received,
        (SELECT IFNULL(SUM(uoli.amount),0) 
         FROM uc_order_line_items uoli 
         WHERE uo.order_id = uoli.order_id
        ) AS line_item_subtotal
        FROM uc_orders uo
        WHERE uo.order_status NOT IN ("future", "canceled")
        AND uo.uid = 4172;

Nginx serves .php files as downloads, instead of executing them

I had similar problem which was resolved by emptying the browser cache (also worked fine with different browser).

Python urllib2: Receive JSON response from url

Though I guess it has already answered I would like to add my little bit in this

import json
import urllib2
class Website(object):
    def __init__(self,name): = name 
    def dump(self): urllib2.urlopen(

    def convJSON(self):
         data=  json.load(self.dump())
     print data

domain = Website("")

Note : object passed to json.load() should support .read() , therefore urllib2.urlopen( would not work . Doamin passed should be provided with protocol in this case http

Gradle Build Android Project "Could not resolve all dependencies" error

I had this message in Android Studio 2.1.1 in the Gradle Build tab. I installed a lot of files from the SDK Manager but it did not help.

I needed to click the next tab "Gradle Sync". There was a link "Install Repository and sync project" which installed the "Android Support Repository".

When and why to 'return false' in JavaScript?

When using jQuery's each function, returning true or false has meaning. See the doc

LabelEncoder: TypeError: '>' not supported between instances of 'float' and 'str'

Or use a cast with split to uniform type of str

unique, counts = numpy.unique(str(a).split(), return_counts=True)

How to retrieve the last autoincremented ID from a SQLite table?

With SQL Server you'd SELECT SCOPE_IDENTITY() to get the last identity value for the current process.

With SQlite, it looks like for an autoincrement you would do

SELECT last_insert_rowid()

immediately after your insert.[email protected]/msg09429.html

In answer to your comment to get this value you would want to use SQL or OleDb code like:

using (SqlConnection conn = new SqlConnection(connString))
    string sql = "SELECT last_insert_rowid()";
    SqlCommand cmd = new SqlCommand(sql, conn);
    int lastID = (Int32) cmd.ExecuteScalar();

Dynamic Height Issue for UITableView Cells (Swift)

This strange bug was solved through Interface Builder parameters as the other answers did not resolve the issue.

All I did was make the default label size larger than the content potentially could be and have it reflected in the estimatedRowHeight height too. Previously, I set the default row height in Interface Builder to 88px and reflected it like so in my controller viewDidLoad():

self.tableView.rowHeight = UITableViewAutomaticDimension
self.tableView.estimatedRowHeight = 88.0

But that didn't work. So I realized that content wouldn't ever become larger than maybe 100px, so I set the default cell height to 108px (larger than the potential content) and reflected it like so in the controller viewDidLoad():

self.tableView.rowHeight = UITableViewAutomaticDimension
self.tableView.estimatedRowHeight = 108.0

This actually allowed the code to shrink down the initial labels to the correct size. In other words, it never expanded out to a larger size, but could always shrink down... Also, no additional self.tableView.reloadData() was needed in viewWillAppear().

I know this does not cover highly variable content sizes, but this worked in my situation where the content had a maximum possible character count.

Not sure if this is a bug in Swift or Interface Builder but it works like a charm. Give it a try!

Displaying the Error Messages in Laravel after being Redirected from controller

$validator = Validator::make($request->all(), [ 'email' => 'required|email', 'password' => 'required', ]);

if ($validator->fails()) { return $validator->errors(); }

How can I make my custom objects Parcelable?

IntelliJ IDEA and Android Studio have plugins for this:

These plugins generate Android Parcelable boilerplate code based on fields in the class.

Plugin demo

How to process a file in PowerShell line-by-line as a stream

If you are really about to work on multi-gigabyte text files then do not use PowerShell. Even if you find a way to read it faster processing of huge amount of lines will be slow in PowerShell anyway and you cannot avoid this. Even simple loops are expensive, say for 10 million iterations (quite real in your case) we have:

# "empty" loop: takes 10 seconds
measure-command { for($i=0; $i -lt 10000000; ++$i) {} }

# "simple" job, just output: takes 20 seconds
measure-command { for($i=0; $i -lt 10000000; ++$i) { $i } }

# "more real job": 107 seconds
measure-command { for($i=0; $i -lt 10000000; ++$i) { $i.ToString() -match '1' } }

UPDATE: If you are still not scared then try to use the .NET reader:

$reader = [System.IO.File]::OpenText("my.log")
try {
    for() {
        $line = $reader.ReadLine()
        if ($line -eq $null) { break }
        # process the line
finally {


There are comments about possibly better / shorter code. There is nothing wrong with the original code with for and it is not pseudo-code. But the shorter (shortest?) variant of the reading loop is

$reader = [System.IO.File]::OpenText("my.log")
while($null -ne ($line = $reader.ReadLine())) {

Print PHP Call Stack

please take a look at this utils class, may be helpful:


/* first caller */

/* list the entire list of calls */

Source class:

How do I handle a click anywhere in the page, even when a certain element stops the propagation?

document.body.addEventListener("keyup", function(event) {
  if (event.keyCode === 13) {
  console.log('clicked ;)');


Force file download with php using header()

The problem was that I used ajax to post the message to the server, when I used a direct link to download the file everything worked fine.

I used this other Stackoverflow Q&A material instead, it worked great for me:


UEFA or FIFA don't seem to provide any API to get the information you want. However, there are some third-party services which support that:

  • OPTA - Both commercial and free. They have incredible database about matches. currently uses it.

  • Others: livescoreboards, xmlsoccer, ...

Is it still valid to use IE=edge,chrome=1?

<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" /> serves two purposes.

  1. IE=edge: specifies that IE should run in the highest mode available to that version of IE as opposed to a compatability mode; IE8 can support up to IE8 modes, IE9 can support up to IE9 modes, and so on.
  2. chrome=1: specifies that Google Chrome frame should start if the user has it installed

The IE=edge flag is still relevant for IE versions 10 and below. IE11 sets this mode as the default.

As for the chrome flag, you can leave it if your users still use Chrome Frame. Despite support and updates for Chrome Frame ending, one can still install and use the final release. If you remove the flag, Chrome Frame will not be activated when installed. For other users, chrome=1 will do nothing more than consume a few bytes of bandwidth.

I recommend you analyze your audience and see if their browsers prohibit any needed features and then decide. Perhaps it might be better to encourage them to use a more modern, evergreen browser.

Note, the W3C validator will flag chrome=1 as an error:

Error: A meta element with an http-equiv attribute whose value is
X-UA-Compatible must have a content attribute with the value IE=edge.

Angular and debounce

For anyone using lodash, it is extremely easy to debounce any function:

changed = _.debounce(function() {
    console.log("name changed!");
}, 400);

then just throw something like this into your template:

<(input)="changed($" />

Python vs Cpython

The original, and standard, implementation of Python is usually called CPython when you want to contrast it with the other options (and just plain “Python” otherwise). This name comes from the fact that it is coded in portable ANSI C language code. This is the Python that you fetch from, get with the ActivePython and Enthought distributions, and have automatically on most Linux and Mac OS X machines. If you’ve found a preinstalled version of Python on your machine, it’s probably CPython, unless your company or organization is using Python in more specialized ways.

Unless you want to script Java or .NET applications with Python or find the benefits of Stackless or PyPy compelling, you probably want to use the standard CPython system. Because it is the reference implementation of the language, it tends to run the fastest, be the most complete, and be more up-to-date and robust than the alternative systems.

Short form for Java if statement

name = ( (city.getName() == null)? "N/A" : city.getName() );

firstly the condition (city.getName() == null) is checked. If yes, then "N/A" is assigned to name or simply name="N/A" or else the value from city.getName() is assigned to name, i.e. name=city.getName().

Things to look out here:

  1. condition is in the parenthesis followed by a question mark. That's why I write (city.getName() == null)?. Here the question mark is right after the condition. Easy to see/read/guess even!
  2. value left of colon (:) and value right of colon (a) value left of colon is assigned when condition is true, else the value right of colon is assigned to the variable.

here's a reference:

how to remove json object key and value.?

Here is one more example. (check the reference)

const myObject = {_x000D_
  "employeeid": "160915848",_x000D_
  "firstName": "tet",_x000D_
  "lastName": "test",_x000D_
  "email": "[email protected]",_x000D_
  "country": "Brasil",_x000D_
  "currentIndustry": "aaaaaaaaaaaaa",_x000D_
  "otherIndustry": "aaaaaaaaaaaaa",_x000D_
  "currentOrganization": "test",_x000D_
  "salary": "1234567"_x000D_
const {otherIndustry, ...otherIndustry2} = myObject;_x000D_
.as-console-wrapper {_x000D_
  max-height: 100% !important;_x000D_
  top: 0;_x000D_

RegEx: Grabbing values between quotation marks

I've been using the following with great success:


It supports nested quotes as well.

For those who want a deeper explanation of how this works, here's an explanation from user ephemient:

([""']) match a quote; ((?=(\\?))\2.) if backslash exists, gobble it, and whether or not that happens, match a character; *? match many times (non-greedily, as to not eat the closing quote); \1 match the same quote that was use for opening.

How do I sort a Set to a List in Java?

The answer provided by the OP is not the best. It is inefficient, as it creates a new List and an unnecessary new array. Also, it raises "unchecked" warnings because of the type safety issues around generic arrays.

Instead, use something like this:

public static
<T extends Comparable<? super T>> List<T> asSortedList(Collection<T> c) {
  List<T> list = new ArrayList<T>(c);
  return list;

Here's a usage example:

Map<Integer, String> map = new HashMap<Integer, String>();
/* Add entries to the map. */
/* Now get a sorted list of the *values* in the map. */
Collection<String> unsorted = map.values();
List<String> sorted = Util.asSortedList(unsorted);

Remove ALL white spaces from text

You have to tell replace() to repeat the regex:

.replace(/ /g,'')

The g character makes it a "global" match, meaning it repeats the search through the entire string. Read about this, and other RegEx modifiers available in JavaScript here.

If you want to match all whitespace, and not just the literal space character, use \s instead:


You can also use .replaceAll if you're using a sufficiently recent version of JavaScript, but there's not really any reason to for your specific use case, since catching all whitespace requires a regex, and when using a regex with .replaceAll, it must be global, so you just end up with extra typing:


Could not load type 'System.Runtime.CompilerServices.ExtensionAttribute' from assembly 'mscorlib

I had this exact same problem with a site (Kentico CMS), starting development in 4.5, finding out the production server only supports 4.0, tried going back down to target framework of 4.0. Compiling the other posts in this thread (specifically changing target framework to .Net 4 and .Net 4.5 still being referenced). I searched through my solution and found that a handful of the NuGet packages were still using libraries with targetFramework="net45".

packages.config (before):
<?xml version="1.0" encoding="utf-8"?>
  <package id="AutoMapper" version="3.1.0" targetFramework="net45" />
  <package id="EntityFramework" version="5.0.0" targetFramework="net45" />
  <package id="Microsoft.AspNet.WebApi.Client" version="5.0.0" targetFramework="net45" />
  <package id="Newtonsoft.Json" version="4.5.11" targetFramework="net45" />

I changed the projects target framework back to 4.5, removed all NuGet libraries, went back down to 4.0 and re-added the libraries (had to use some previous versions that were not dependent on 4.5).

packages.config (after):
<?xml version="1.0" encoding="utf-8"?>
  <package id="AutoMapper" version="3.1.1" targetFramework="net40" />
  <package id="EntityFramework" version="6.0.2" targetFramework="net40" />
  <package id="Microsoft.AspNet.WebApi.Client" version="4.0.30506.0" targetFramework="net40" />
  <package id="Microsoft.Net.Http" version="2.0.20710.0" targetFramework="net40" />
  <package id="Newtonsoft.Json" version="4.5.11" targetFramework="net40" />

Custom CSS for <audio> tag?

There is not currently any way to style HTML5 <audio> players using CSS. Instead, you can leave off the control attribute, and implement your own controls using Javascript. If you don't want to implement them all on your own, I'd recommend using an existing themeable HTML5 audio player, such as jPlayer. invalid stream header: 7371007E

when I send only one object from the client to server all works well.

when I attempt to send several objects one after another on the same stream I get StreamCorruptedException.

Actually, your client code is writing one object to the server and reading multiple objects from the server. And there is nothing on the server side that is writing the objects that the client is trying to read.

Eclipse cannot load SWT libraries

Simply specify the path to the libraries:

echo "-Djava.library.path=/usr/lib/jni/" >> /etc/eclipse.ini

Easy way to get a test file into JUnit

You can try doing:

String myResource = IOUtils.toString(this.getClass().getResourceAsStream("yourfile.xml")).replace("\n","");

Function not defined javascript

important: in this kind of error you should look for simple mistakes in most cases

besides syntax error, I should say once I had same problem and it was because of bad name I have chosen for function. I have never searched for the reason but I remember that I copied another function and change it to use. I add "1" after the name to changed the function name and I got this error.

Parsing command-line arguments in C

I'd suggest using a library. There's the classic and venerable getopt and I'm sure others.

How To: Execute command line in C#, get STD OUT results

This may not be the best/easiest way, but may be an option:

When you execute from your code, add " > output.txt" and then read in the output.txt file.

How to calculate the CPU usage of a process by PID in Linux from C?

I wrote two little C function based on cafs answer to calculate the user+kernel cpu usage of of an process:

Check OS version in Swift?


  • Xcode 10.2.1 (10E1001), Swift 5




extension OperatingSystemVersion {
    func getFullVersion(separator: String = ".") -> String {
        return "\(majorVersion)\(separator)\(minorVersion)\(separator)\(patchVersion)"

let os = ProcessInfo().operatingSystemVersion
print(os.majorVersion)          // 12
print(os.minorVersion)          // 2
print(os.patchVersion)          // 0
print(os.getFullVersion())      // 12.2.0

How to layout multiple panels on a jFrame? (java)

The JPanel is actually only a container where you can put different elements in it (even other JPanels). So in your case I would suggest one big JPanel as some sort of main container for your window. That main panel you assign a Layout that suits your needs ( here is an introduction to the layouts).

After you set the layout to your main panel you can add the paint panel and the other JPanels you want (like those with the text in it..).

  JPanel mainPanel = new JPanel();
  mainPanel.setLayout(new BoxLayout(mainPanel, BoxLayout.Y_AXIS));

  JPanel paintPanel = new JPanel();
  JPanel textPanel = new JPanel();


This is just an example that sorts all sub panels vertically (Y-Axis). So if you want some other stuff at the bottom of your mainPanel (maybe some icons or buttons) that should be organized with another layout (like a horizontal layout), just create again a new JPanel as a container for all the other stuff and set setLayout(new BoxLayout(mainPanel, BoxLayout.X_AXIS).

As you will find out, the layouts are quite rigid and it may be difficult to find the best layout for your panels. So don't give up, read the introduction (the link above) and look at the pictures – this is how I do it :)

Or you can just use NetBeans to write your program. There you have a pretty easy visual editor (drag and drop) to create all sorts of Windows and Frames. (only understanding the code afterwards is ... tricky sometimes.)


Since there are some many people interested in this question, I wanted to provide a complete example of how to layout a JFrame to make it look like OP wants it to.

The class is called MyFrame and extends swings JFrame

public class MyFrame extends javax.swing.JFrame{

    // these are the components we need.
    private final JSplitPane splitPane;  // split the window in top and bottom
    private final JPanel topPanel;       // container panel for the top
    private final JPanel bottomPanel;    // container panel for the bottom
    private final JScrollPane scrollPane; // makes the text scrollable
    private final JTextArea textArea;     // the text
    private final JPanel inputPanel;      // under the text a container for all the input elements
    private final JTextField textField;   // a textField for the text the user inputs
    private final JButton button;         // and a "send" button

    public MyFrame(){

        // first, lets create the containers:
        // the splitPane devides the window in two components (here: top and bottom)
        // users can then move the devider and decide how much of the top component
        // and how much of the bottom component they want to see.
        splitPane = new JSplitPane();

        topPanel = new JPanel();         // our top component
        bottomPanel = new JPanel();      // our bottom component

        // in our bottom panel we want the text area and the input components
        scrollPane = new JScrollPane();  // this scrollPane is used to make the text area scrollable
        textArea = new JTextArea();      // this text area will be put inside the scrollPane

        // the input components will be put in a separate panel
        inputPanel = new JPanel();
        textField = new JTextField();    // first the input field where the user can type his text
        button = new JButton("send");    // and a button at the right, to send the text

        // now lets define the default size of our window and its layout:
        setPreferredSize(new Dimension(400, 400));     // let's open the window with a default size of 400x400 pixels
        // the contentPane is the container that holds all our components
        getContentPane().setLayout(new GridLayout());  // the default GridLayout is like a grid with 1 column and 1 row,
        // we only add one element to the window itself
        getContentPane().add(splitPane);               // due to the GridLayout, our splitPane will now fill the whole window

        // let's configure our splitPane:
        splitPane.setOrientation(JSplitPane.VERTICAL_SPLIT);  // we want it to split the window verticaly
        splitPane.setDividerLocation(200);                    // the initial position of the divider is 200 (our window is 400 pixels high)
        splitPane.setTopComponent(topPanel);                  // at the top we want our "topPanel"
        splitPane.setBottomComponent(bottomPanel);            // and at the bottom we want our "bottomPanel"

        // our topPanel doesn't need anymore for this example. Whatever you want it to contain, you can add it here
        bottomPanel.setLayout(new BoxLayout(bottomPanel, BoxLayout.Y_AXIS)); // BoxLayout.Y_AXIS will arrange the content vertically

        bottomPanel.add(scrollPane);                // first we add the scrollPane to the bottomPanel, so it is at the top
        scrollPane.setViewportView(textArea);       // the scrollPane should make the textArea scrollable, so we define the viewport
        bottomPanel.add(inputPanel);                // then we add the inputPanel to the bottomPanel, so it under the scrollPane / textArea

        // let's set the maximum size of the inputPanel, so it doesn't get too big when the user resizes the window
        inputPanel.setMaximumSize(new Dimension(Integer.MAX_VALUE, 75));     // we set the max height to 75 and the max width to (almost) unlimited
        inputPanel.setLayout(new BoxLayout(inputPanel, BoxLayout.X_AXIS));   // X_Axis will arrange the content horizontally

        inputPanel.add(textField);        // left will be the textField
        inputPanel.add(button);           // and right the "send" button

        pack();   // calling pack() at the end, will ensure that every layout and size we just defined gets applied before the stuff becomes visible

    public static void main(String args[]){
        EventQueue.invokeLater(new Runnable(){
            public void run(){
                new MyFrame().setVisible(true);

Please be aware that this is only an example and there are multiple approaches to layout a window. It all depends on your needs and if you want the content to be resizable / responsive. Another really good approach would be the GridBagLayout which can handle quite complex layouting, but which is also quite complex to learn.

How to group pandas DataFrame entries by date in a non-unique column

I'm using pandas 0.16.2. This has better performance on my large dataset:


Using the dt option and playing around with weekofyear, dayofweek etc. becomes far easier.

How do you simulate Mouse Click in C#?

I have tried the code that Marcos posted and it didn't worked for me. Whatever i was given to the Y coordinate the cursor didn't moved on Y axis. The code below will work if you want the position of the cursor relative to the left-up corner of your desktop, not relative to your application.

    [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
    public static extern void mouse_event(long dwFlags, long dx, long dy, long cButtons, long dwExtraInfo);
    private const int MOUSEEVENTF_LEFTDOWN = 0x02;
    private const int MOUSEEVENTF_LEFTUP = 0x04;
    private const int MOUSEEVENTF_MOVE = 0x0001;

    public void DoMouseClick()
        X = Cursor.Position.X;
        Y = Cursor.Position.Y;

        //move to coordinates
        pt = (Point)pc.ConvertFromString(X + "," + Y);
        Cursor.Position = pt;       

        //perform click            
        mouse_event(MOUSEEVENTF_LEFTDOWN, 0, 0, 0, 0);
        mouse_event(MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);

I only use mouse_event function to actually perform the click. You can give X and Y what coordinates you want, i used values from textbox:

            X = Convert.ToInt32(tbX.Text);
            Y = Convert.ToInt32(tbY.Text);

Find running median from a stream of integers

If the variance of the input is statistically distributed (e.g. normal, log-normal, etc.) then reservoir sampling is a reasonable way of estimating percentiles/medians from an arbitrarily long stream of numbers.

int n = 0;  // Running count of elements observed so far  
#define SIZE 10000
int reservoir[SIZE];  

  int x = readNumberFromStream();

  if (n < SIZE)
       reservoir[n++] = x;
      int p = random(++n); // Choose a random number 0 >= p < n
      if (p < SIZE)
           reservoir[p] = x;

"reservoir" is then a running, uniform (fair), sample of all input - regardless of size. Finding the median (or any percentile) is then a straight-forward matter of sorting the reservoir and polling the interesting point.

Since the reservoir is fixed size, the sort can be considered to be effectively O(1) - and this method runs with both constant time and memory consumption.

Create an ISO date object in javascript

In node, the Mongo driver will give you an ISO string, not the object. (ex: Mon Nov 24 2014 01:30:34 GMT-0800 (PST)) So, simply convert it to a js Date by: new Date(ISOString);

rails generate model

You need to create new rails application first. Run

rails new mebay
cd mebay
bundle install
rails generate model ...

And try to find Rails 3 tutorial, there are a lot of changes since 2.1 Guides ( are good start point.

How to read and write into file using JavaScript?

Writing this answer for people who wants to get a file to download with specific content from javascript. I was struggling with the same thing.

const data = {name: 'Ronn', age: 27};              //sample json
const a = document.createElement('a');
const blob = new Blob([JSON.stringify(data)]);
a.href = URL.createObjectURL(blob); = 'sample-profile';                     //filename to download;

Check Blob documentation here - Blob MDN

Use of document.getElementById in JavaScript

You're correct in that the document.getElementById("demo") call gets you the element by the specified ID. But you have to look at the rest of the statement to figure out what exactly the code is doing with that element:


You can see here that it's setting the innerHTML of that element to the value of voteable.

get number of columns of a particular row in given excel using Java

There are two Things you can do


int noOfColumns = sh.getRow(0).getPhysicalNumberOfCells();


int noOfColumns = sh.getRow(0).getLastCellNum();

There is a fine difference between them

  1. Option 1 gives the no of columns which are actually filled with contents(If the 2nd column of 10 columns is not filled you will get 9)
  2. Option 2 just gives you the index of last column. Hence done 'getLastCellNum()'

Composer: Command Not Found

Step 1 : Open Your terminal

Step 2 : Run bellow command

          curl -sS | php

Step 3 : After installation run bellow command

          sudo mv composer.phar /usr/local/bin/

Step 4 : Open bash_profile file create alias follow bellow steps

           vim ~/.bash_profile

Step 5 : Add bellow line in bash_profile file

          alias composer="php /usr/local/bin/composer.phar"

Step 6 : Close your terminal and reopen your terminal and run bellow command composer

Running python script inside ipython

How to run a script in Ipython

import os

That should do it

Can't install Scipy through pip

I experienced similar issues with Python 3.7 (3.7.0b4). This was due to some changes regarding some encoding assumptions (Python 3.6 >> Python 3.7)

As a result lots of package installations (e.g. via pip) failed.

Assigning variables with dynamic names in Java

You don't. The closest thing you can do is working with Maps to simulate it, or defining your own Objects to deal with.

How can I do a BEFORE UPDATED trigger with sql server?

Remember that when you use an instead trigger, it will not commit the insert unless you specifically tell it to in the trigger. Instead of really means do this instead of what you normally do, so none of the normal insert actions would happen.

unique combinations of values in selected columns in pandas data frame and count

You can groupby on cols 'A' and 'B' and call size and then reset_index and rename the generated column:

In [26]:

     A    B  count
0   no   no      1
1   no  yes      2
2  yes   no      4
3  yes  yes      3


A little explanation, by grouping on the 2 columns, this groups rows where A and B values are the same, we call size which returns the number of unique groups:


A    B  
no   no     1
     yes    2
yes  no     4
     yes    3
dtype: int64

So now to restore the grouped columns, we call reset_index:


     A    B  0
0   no   no  1
1   no  yes  2
2  yes   no  4
3  yes  yes  3

This restores the indices but the size aggregation is turned into a generated column 0, so we have to rename this:


     A    B  count
0   no   no      1
1   no  yes      2
2  yes   no      4
3  yes  yes      3

groupby does accept the arg as_index which we could have set to False so it doesn't make the grouped columns the index, but this generates a series and you'd still have to restore the indices and so on....:

df1.groupby(['A','B'], as_index=False).size()

A    B  
no   no     1
     yes    2
yes  no     4
     yes    3
dtype: int64

Connecting an input stream to an outputstream

Just because you use a buffer doesn't mean the stream has to fill that buffer. In other words, this should be okay:

public static void copyStream(InputStream input, OutputStream output)
    throws IOException
    byte[] buffer = new byte[1024]; // Adjust if you want
    int bytesRead;
    while ((bytesRead = != -1)
        output.write(buffer, 0, bytesRead);

That should work fine - basically the read call will block until there's some data available, but it won't wait until it's all available to fill the buffer. (I suppose it could, and I believe FileInputStream usually will fill the buffer, but a stream attached to a socket is more likely to give you the data immediately.)

I think it's worth at least trying this simple solution first.

Setting DataContext in XAML in WPF

First of all you should create property with employee details in the Employee class:

public class Employee
    public Employee()
        EmployeeDetails = new EmployeeDetails();
        EmployeeDetails.EmpID = 123;
        EmployeeDetails.EmpName = "ABC";

    public EmployeeDetails EmployeeDetails { get; set; }

If you don't do that, you will create instance of object in Employee constructor and you lose reference to it.

In the XAML you should create instance of Employee class, and after that you can assign it to DataContext.

Your XAML should look like this:

<Window x:Class="SampleApplication.MainWindow"
    Title="MainWindow" Height="350" Width="525"
        <local:Employee x:Key="Employee" />
    <Grid DataContext="{StaticResource Employee}">
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="200" />

        <Label Grid.Row="0" Grid.Column="0" Content="ID:"/>
        <Label Grid.Row="1" Grid.Column="0" Content="Name:"/>
        <TextBox Grid.Column="1" Grid.Row="0" Margin="3" Text="{Binding EmployeeDetails.EmpID}" />
        <TextBox Grid.Column="1" Grid.Row="1" Margin="3" Text="{Binding EmployeeDetails.EmpName}" />

Now, after you created property with employee details you should binding by using this property:

Text="{Binding EmployeeDetails.EmpID}"

How to convert CLOB to VARCHAR2 inside oracle pl/sql

Converting VARCHAR2 to CLOB

In PL/SQL a CLOB can be converted to a VARCHAR2 with a simple assignment, SUBSTR, and other methods. A simple assignment will only work if the CLOB is less then or equal to the size of the VARCHAR2. The limit is 32767 in PL/SQL and 4000 in SQL (although 12c allows 32767 in SQL).

For example, this code converts a small CLOB through a simple assignment and then coverts the beginning of a larger CLOB.

    v_small_clob clob := lpad('0', 1000, '0');
    v_large_clob clob := lpad('0', 32767, '0') || lpad('0', 32767, '0');
    v_varchar2   varchar2(32767);
    v_varchar2 := v_small_clob;
    v_varchar2 := substr(v_large_clob, 1, 32767);


The above code does not convert the value to a LONG. It merely looks that way because of limitations with PL/SQL debuggers and strings over 999 characters long.

For example, in PL/SQL Developer, open a Test window and add and debug the above code. Right-click on v_varchar2 and select "Add variable to Watches". Step through the code and the value will be set to "(Long Value)". There is a ... next to the text but it does not display the contents. PLSQL Developer Long Value


I suspect the real problem here is with C# but I don't know how enough about C# to debug the problem.

Can I stop 100% Width Text Boxes from extending beyond their containers?

Is there any way to make a text box fill the width of its container without expanding beyond it?

Yes: by using the CSS3 property ‘box-sizing: border-box’, you can redefine what ‘width’ means to include the external padding and border.

Unfortunately because it's CSS3, support isn't very mature, and as the spec process isn't finished yet, it has different temporary names in browsers in the meantime. So:

input.wide {
    width: 100%;
    box-sizing: border-box;
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;

The old-school alternative is simply to put a quantity of ‘padding-right’ on the enclosing <div> or <td> element equal to about how much extra left-and-right padding/border in ‘px’ you think browsers will give the input. (Typically 6px for IE<8.)

Check if a process is running or not on Windows with Python

This works nicely

def running():
    n=0# number of instances of the program running 
    prog=[line.split() for line in subprocess.check_output("tasklist").splitlines()]
    [prog.pop(e) for e in [0,1,2]] #useless 
    for task in prog:
        if task[0]=="itunes.exe":
    if n>0:
        return True
        return False

How to listen to the window scroll event in a VueJS component?

In my experience, using an event listener on scroll can create a lot of noise due to piping into that event stream, which can cause performance issues if you are executing a bulky handleScroll function.

I often use the technique shown here in the highest rated answer, but I add debounce on top of it, usually about 100ms yields good performance to UX ratio.

Here is an example using the top-rated answer with Lodash debounce added:

import debounce from 'lodash/debounce';

export default {
  methods: {
    handleScroll(event) {
      // Any code to be executed when the window is scrolled
      this.isUserScrolling = (window.scrollY > 0);
      console.log('calling handleScroll');

  created() {
    this.handleDebouncedScroll = debounce(this.handleScroll, 100);
    window.addEventListener('scroll', this.handleDebouncedScroll);

  beforeDestroy() {
    // I switched the example from `destroyed` to `beforeDestroy`
    // to exercise your mind a bit. This lifecycle method works too.
    window.removeEventListener('scroll', this.handleDebouncedScroll);

Try changing the value of 100 to 0 and 1000 so you can see the difference in how/when handleScroll is called.

BONUS: You can also accomplish this in an even more concise and reuseable manner with a library like vue-scroll. It is a great use case for you to learn about custom directives in Vue if you haven't seen those yet. Check out

This is also a great tutorial by Sarah Drasner in the Vue docs:

Logout button php

Instead of a button, put a link and navigate it to another page

<a href="logout.php">Logout</a>

Then in logout.php page, use

header('Location: login.php');

Test if a string contains any of the strings from an array

If you use Java 8 or above, you can rely on the Stream API to do such thing:

public static boolean containsItemFromArray(String inputString, String[] items) {
    // Convert the array of String items as a Stream
    // For each element of the Stream call inputString.contains(element)
    // If you have any match returns true, false otherwise

Assuming that you have a big array of big String to test you could also launch the search in parallel by calling parallel(), the code would then be:


How to get the current time in YYYY-MM-DD HH:MI:Sec.Millisecond format in Java?



    ZoneId.of( "America/Montreal" ) 
.format(  DateTimeFormatter.ISO_LOCAL_DATE_TIME )
.replace( "T" , " " )

2016-05-06 19:24:25.694


In Java 8 and later, we have the java.time framework built into Java 8 and later. These new classes supplant the troublesome old java.util.Date/.Calendar classes. The new classes are inspired by the highly successful Joda-Time framework, intended as its successor, similar in concept but re-architected. Defined by JSR 310. Extended by the ThreeTen-Extra project. See the Tutorial.

Be aware that java.time is capable of nanosecond resolution (9 decimal places in fraction of second), versus the millisecond resolution (3 decimal places) of both java.util.Date & Joda-Time. So when formatting to display only 3 decimal places, you could be hiding data.

If you want to eliminate any microseconds or nanoseconds from your data, truncate.

Instant instant2 = instant.truncatedTo( ChronoUnit.MILLIS ) ;

The java.time classes use ISO 8601 format by default when parsing/generating strings. A Z at the end is short for Zulu, and means UTC.

An Instant represents a moment on the timeline in UTC with resolution of up to nanoseconds. Capturing the current moment in Java 8 is limited to milliseconds, with a new implementation in Java 9 capturing up to nanoseconds depending on your computer’s hardware clock’s abilities.

Instant instant = (); // Current date-time in UTC.
String output = instant.toString ();


Replace the T in the middle with a space, and the Z with nothing, to get your desired output.

String output = instant.toString ().replace ( "T" , " " ).replace( "Z" , "" ; // Replace 'T', delete 'Z'. I recommend leaving the `Z` or any other such [offset-from-UTC][7] or [time zone][7] indicator to make the meaning clear, but your choice of course.

2016-05-06 23:24:25.694

As you don't care about including the offset or time zone, make a "local" date-time unrelated to any particular locality.

String output = ( ).toString ().replace ( "T", " " );


The highly successful Joda-Time library was the inspiration for the java.time framework. Advisable to migrate to java.time when convenient.

The ISO 8601 format includes milliseconds, and is the default for the Joda-Time 2.4 library.

System.out.println( "Now: " + new DateTime ( DateTimeZone.UTC ) );

When run…

Now: 2013-11-26T20:25:12.014Z

Also, you can ask for the milliseconds fraction-of-a-second as a number, if needed:

int millisOfSecond = myDateTime.getMillisOfSecond ();

How to get selected value of a html select with

If you would use asp:dropdownlist you could select it easier by testSelect.Text.

Now you'd have to do a Request.Form["testSelect"] to get the value after pressed btnTes.

Hope it helps.

EDIT: You need to specify a name of the select (not only ID) to be able to Request.Form["testSelect"]

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

Ubuntu 14.04 LTS, in Amazon EC2. The following steps resolved this issue for me:

1. Edit server.xml and change port="8080" to "80"

sudo vi /var/lib/tomcat7/conf/server.xml

<Connector connectionTimeout="20000" port="8080" protocol="HTTP/1.1" redirectPort="8443"/>

2. Edit tomcat7 file (if the file is not created then you need to create it)

sudo vi /etc/default/tomcat7

uncomment and change #AUTHBIND=no to yes

3. Install authbind

sudo apt-get install authbind

4. Run the following commands to provide tomcat7 read+execute on port 80.

sudo touch /etc/authbind/byport/80
sudo chmod 500 /etc/authbind/byport/80
sudo chown tomcat7 /etc/authbind/byport/80

5. Restart tomcat:

sudo /etc/init.d/tomcat7 restart

How would you do a "not in" query with LINQ?

You can use a combination of Where and Any for finding not in:

var NotInRecord =list1.Where(p => !list2.Any(p2 => p2.Email  == p.Email));

@Autowired - No qualifying bean of type found for dependency

I ran in to this recently, and as it turned out, I've imported the wrong annotation in my service class. Netbeans has an option to hide import statements, that's why I did not see it for some time.

I've used @org.jvnet.hk2.annotations.Service instead of @org.springframework.stereotype.Service.

How do I (or can I) SELECT DISTINCT on multiple columns?


is roughly equivalent to:

SELECT a,b,c FROM t GROUP BY a,b,c

It's a good idea to get used to the GROUP BY syntax, as it's more powerful.

For your query, I'd do it like this:

UPDATE sales
SET status='ACTIVE'
    SELECT id
    FROM sales S
        SELECT saleprice, saledate
        FROM sales
        GROUP BY saleprice, saledate
        HAVING COUNT(*) = 1 
    ) T
    ON S.saleprice=T.saleprice AND s.saledate=T.saledate

Fatal error: Call to undefined function socket_create()

Follow these steps if you're on openSuse or SUSE.

Install php7 if it's not already installed.

zypper in php7

If you have php7 installed, update it with:

zypper update php7

Install php7-sockets

zypper in php7-sockets

Chart.js v2 - hiding grid lines

The code below removes remove grid lines from chart area only not the ones in x&y axis labels

Chart.defaults.scale.gridLines.drawOnChartArea = false;

Passing two command parameters using a WPF binding

This task can also be solved with a different approach. Instead of programming a converter and enlarging the code in the XAML, you can also aggregate the various parameters in the ViewModel. As a result, the ViewModel then has one more property that contains all parameters.

An example of my current application, which also let me deal with the topic. A generic RelayCommand is required:

The ViewModelBase is extended here by a command SaveAndClose. The generic type is a named tuple that represents the various parameters.

public ICommand SaveAndCloseCommand => saveAndCloseCommand ??= new RelayCommand<(IBaseModel Item, Window Window)>
    (execute =>
        execute.Window?.Close(); // if NULL it isn't closed.
    canExecute =>
        return canExecute.Item?.IsItemValide ?? false;
private ICommand saveAndCloseCommand;

Then it contains a property according to the generic type:

public (IBaseModel Item, Window Window) SaveAndCloseParameter 
    get => saveAndCloseParameter ; 
        SetProperty(ref saveAndCloseParameter, value);
private (IBaseModel Item, Window Window) saveAndCloseParameter;

The XAML code of the view then looks like this: (Pay attention to the classic click event)

    Command="{Binding SaveAndCloseCommand}" 
    CommandParameter="{Binding SaveAndCloseParameter}" 
    Height="25" Width="100" />
    Command="{Binding SaveAndCloseCommand}" 
    CommandParameter="{Binding SaveAndCloseParameter}" 
    Height="25" Width="100" />

and in the code behind of the view, then evaluating the click events, which then set the parameter property.

private void ButtonApply_Click(object sender, RoutedEventArgs e)
    computerViewModel.SaveAndCloseParameter = (computerViewModel.Computer, null);

private void ButtonSave_Click(object sender, RoutedEventArgs e)
    computerViewModel.SaveAndCloseParameter = (computerViewModel.Computer, this);

Personally, I think that using the click events is not a break with the MVVM pattern. The program flow control is still located in the area of ??the ViewModel.

Get input value from TextField in iOS alert in Swift

Updated for Swift 3 and above:

//1. Create the alert controller.
let alert = UIAlertController(title: "Some Title", message: "Enter a text", preferredStyle: .alert)

//2. Add the text field. You can configure it however you need.
alert.addTextField { (textField) in
    textField.text = "Some default text"

// 3. Grab the value from the text field, and print it when the user clicks OK.
alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { [weak alert] (_) in
    let textField = alert.textFields![0] // Force unwrapping because we know it exists.
    print("Text field: \(textField.text)")

// 4. Present the alert.
self.present(alert, animated: true, completion: nil)

Swift 2.x

Assuming you want an action alert on iOS:

//1. Create the alert controller.            
var alert = UIAlertController(title: "Some Title", message: "Enter a text", preferredStyle: .Alert)

//2. Add the text field. You can configure it however you need.
alert.addTextFieldWithConfigurationHandler({ (textField) -> Void in
    textField.text = "Some default text."

//3. Grab the value from the text field, and print it when the user clicks OK. 
alert.addAction(UIAlertAction(title: "OK", style: .Default, handler: { [weak alert] (action) -> Void in
    let textField = alert.textFields![0] as UITextField
    println("Text field: \(textField.text)")

// 4. Present the alert.
self.presentViewController(alert, animated: true, completion: nil)

Java switch statement: Constant expression required, but it IS constant

Got this error in Android while doing something like this:

 roleSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

            switch (parent.getItemAtPosition(position)) {
                case ADMIN_CONSTANT: //Threw the error


despite declaring a constant:

public static final String ADMIN_CONSTANT= "Admin";

I resolved the issue by changing my code to this:

roleSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

            String selectedItem = String.valueOf(parent.getItemAtPosition(position));
            switch (selectedItem) {
                case ADMIN_CONSTANT:


PHP shorthand for isset()?

Update for PHP 7 (thanks shock_gone_wild)

PHP 7 introduces the so called null coalescing operator which simplifies the below statements to:

$var = $var ?? "default";

Before PHP 7

No, there is no special operator or special syntax for this. However, you could use the ternary operator:

$var = isset($var) ? $var : "default";

Or like this:

isset($var) ?: $var = 'default';

Convert comma separated string of ints to int array

--EDIT-- It looks like I took his question heading too literally - he was asking for an array of ints rather than a List --EDIT ENDS--

Yet another helper method...

private static int[] StringToIntArray(string myNumbers)
    List<int> myIntegers = new List<int>();
    Array.ForEach(myNumbers.Split(",".ToCharArray()), s =>
        int currentInt;
        if (Int32.TryParse(s, out currentInt))
    return myIntegers.ToArray();

quick test code for it, too...

static void Main(string[] args)
    string myNumbers = "1,2,3,4,5";
    int[] myArray = StringToIntArray(myNumbers);
    Console.WriteLine(myArray.Sum().ToString()); // sum is 15.

    myNumbers = "1,2,3,4,5,6,bad";
    myArray = StringToIntArray(myNumbers);
    Console.WriteLine(myArray.Sum().ToString()); // sum is 21


Maven- No plugin found for prefix 'spring-boot' in the current project and in the plugin groups

If you are using Spring Boot for application, forgetting to add


can cause this issue, as well as missing these lines


Elegant way to create empty pandas DataFrame with NaN of type float

You could specify the dtype directly when constructing the DataFrame:

>>> df = pd.DataFrame(index=range(0,4),columns=['A'], dtype='float')
>>> df.dtypes
A    float64
dtype: object

Specifying the dtype forces Pandas to try creating the DataFrame with that type, rather than trying to infer it.

Close iOS Keyboard by touching anywhere using Swift

Just one line of code in viewDidLoad() method:

view.addGestureRecognizer(UITapGestureRecognizer(target: view, action: #selector(UIView.endEditing(_:))))

How to display images from a folder using php - PHP

You have two ways to do that:

METHOD 1. The secure way.

Put the images on /www/htdocs/

    $www_root = 'http://localhost/images';
    $dir = '/var/www/images';
    $file_display = array('jpg', 'jpeg', 'png', 'gif');

    if ( file_exists( $dir ) == false ) {
       echo 'Directory \'', $dir, '\' not found!';
    } else {
       $dir_contents = scandir( $dir );

        foreach ( $dir_contents as $file ) {
           $file_type = strtolower( end( explode('.', $file ) ) );
           if ( ($file !== '.') && ($file !== '..') && (in_array( $file_type, $file_display)) ) {
              echo '<img src="', $www_root, '/', $file, '" alt="', $file, '"/>';

METHOD 2. Unsecure but more flexible.

Put the images on any directory (apache must have permission to read the file).

    $dir = '/home/user/Pictures';
    $file_display = array('jpg', 'jpeg', 'png', 'gif');

    if ( file_exists( $dir ) == false ) {
       echo 'Directory \'', $dir, '\' not found!';
    } else {
       $dir_contents = scandir( $dir );

        foreach ( $dir_contents as $file ) {
           $file_type = strtolower( end( explode('.', $file ) ) );
           if ( ($file !== '.') && ($file !== '..') && (in_array( $file_type, $file_display)) ) {
              echo '<img src="file_viewer.php?file=', base64_encode($dir . '/' . $file), '" alt="', $file, '"/>';

And create another script to read the image file.

    $filename = base64_decode($_GET['file']);
    // Check the folder location to avoid exploit
    if (dirname($filename) == '/home/user/Pictures')
        echo file_get_contents($filename);

how to remove time from datetime

First thing's first, if your dates are in varchar format change that, store dates as dates it will save you a lot of headaches and it is something that is best done sooner rather than later. The problem will only get worse.

Secondly, once you have a date DO NOT convert the date to a varchar! Keep it in date format and use formatting on the application side to get the required date format.

There are various methods to do this depending on your DBMS:

SQL-Server 2008 and later:


SQL-Server 2005 and Earlier








If you need to use culture specific formatting in your report you can either explicitly state the format of the receiving text box (e.g. dd/MM/yyyy), or you can set the language so that it shows the relevant date format for that language.

Either way this is much better handled outside of SQL as converting to varchar within SQL will impact any sorting you may do in your report.

If you cannot/will not change the datatype to DATETIME, then still convert it to a date within SQL (e.g. CONVERT(DATETIME, yourField)) before sending to report services and handle it as described above.

Function to convert timestamp to human date in javascript

This is what I did for the instagram API. converted timestamp with date method by multiplying by 1000. and then added all entity individually like (year, months, etc)

created the custom month list name and mapped with getMonth() method which returns the index of the month.


// Unixtimestamp

// Months array
var months_arr = ['January','February','March','April','May','June','July','August','September','October','November','December'];

// Convert timestamp to milliseconds
var date = new Date(unixtimestamp*1000);

// Year
var year = date.getFullYear();

// Month
var month = months_arr[date.getMonth()];

// Day
var day = date.getDate();

// Hours
var hours = date.getHours();

// Minutes
var minutes = "0" + date.getMinutes();

// Seconds
var seconds = "0" + date.getSeconds();

// Display date time in MM-dd-yyyy h:m:s format
var fulldate = month+' '+day+'-'+year+' '+hours + ':' + minutes.substr(-2) + ':' + seconds.substr(-2);

// filtered fate
var convdataTime = month+' '+day;
return convdataTime;

Call with stamp argument convertStampDate('1382086394000')

and thats it.

CSS: Center block, but align contents to the left

If I understand you well, you need to use to center a container (or block)

margin-left: auto;
margin-right: auto;

and to left align it's contents:

text-align: left;

jQuery or CSS selector to select all IDs that start with some string

$('div[id ^= "player_"]');

This worked for all Div starts with "players_" keyword and display it.

Byte[] to ASCII

You can use:


But sometimes you will get a weird number instead of the string you want. In that case, your original string may have some hexadecimal character when you see it. If it's the case, you may want to try this:


Or as a last resort:


Converting Varchar Value to Integer/Decimal Value in SQL Server

You can use it without casting such as:

select sum(`stuff`) as mySum from test;

Or cast it to decimal:

select sum(cast(`stuff` as decimal(4,2))) as mySum from test;



For SQL Server, you can use:

select sum(cast(stuff as decimal(5,2))) as mySum from test;


How to copy files from host to Docker container?

I tried most of the (upvoted) solutions here but in docker 17.09 (in 2018) there is no longer /var/lib/docker/aufs folder.

This simple docker cp solved this task.

docker cp c:\path\to\local\file container_name:/path/to/target/dir/

How to get container_name?

 docker ps 

There is a NAMES section. Don't use aIMAGE.

Assert an object is a specific type

You can use the assertThat method and the Matchers that comes with JUnit.

Take a look at this link that describes a little bit about the JUnit Matchers.


public class BaseClass {

public class SubClass extends BaseClass {


import org.junit.Test;

import static org.hamcrest.CoreMatchers.instanceOf;
import static org.junit.Assert.assertThat;

 * @author maba, 2012-09-13
public class InstanceOfTest {

    public void testInstanceOf() {
        SubClass subClass = new SubClass();
        assertThat(subClass, instanceOf(BaseClass.class));

IF EXIST C:\directory\ goto a else goto b problems windows XP batch files

From the help (if /?):

The ELSE clause must occur on the same line as the command after the IF.  For

    IF EXIST filename. (
        del filename.
    ) ELSE (
        echo filename. missing.

The following would NOT work because the del command needs to be terminated
by a newline:

    IF EXIST filename. del filename. ELSE echo filename. missing

Nor would the following work, since the ELSE command must be on the same line
as the end of the IF command:

    IF EXIST filename. del filename.
    ELSE echo filename. missing

How to add Button over image using CSS?

<div class="content"> 
  Counter-Strike 1.6 Steam 
     <img src="images/CSsteam.png">
     <a href="#">Koupit</a>

/*Use this css*/
content {
width: 182px; /*328 co je 1/3 - 20margin left*/
height: 121px;
line-height: 20px;
margin-top: 0px;
margin-left: 9px;
content a{

getString Outside of a Context or Activity

You can do this in Kotlin by creating a class that extends Application and then use its context to call the resources anywhere in your code

Your App class will look like this

 class App : Application() {
    override fun onCreate() {
        context = this

    companion object {
        var context: Context? = null
            private set

Declare your Application class in AndroidManifest.xml (very important)

        android:name=".App" //<--Your declaration Here
            android:name=".SplashActivity"  android:theme="@style/SplashTheme">
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

        <activity android:name=".MainActivity"/>

To access e.g. a string file use the following code


How to select data where a field has a min value in MySQL?

this will give you result that has the minimum price on all records.

FROM pieces
WHERE price =  ( SELECT MIN(price) FROM pieces )

Why is it bad practice to call System.gc()?

In my experience, using System.gc() is effectively a platform-specific form of optimization (where "platform" is the combination of hardware architecture, OS, JVM version and possible more runtime parameters such as RAM available), because its behaviour, while roughly predictable on a specific platform, can (and will) vary considerably between platforms.

Yes, there are situations where System.gc() will improve (perceived) performance. On example is if delays are tolerable in some parts of your app, but not in others (the game example cited above, where you want GC to happen at the start of a level, not during the level).

However, whether it will help or hurt (or do nothing) is highly dependent on the platform (as defined above).

So I think it is valid as a last-resort platform-specific optimization (i.e. if other performance optimizations are not enough). But you should never call it just because you believe it might help(without specific benchmarks), because chances are it will not.

How add class='active' to html menu with php

Your index.php code is correct. I am including the updated code for common.php below then I will explain the differences.

     $class = ($page == 'one') ? 'class="active"' : '';
     $nav = <<<EOD
        <div id="nav">
               <li><a $class href="index.php">Tab1</a>/</li>
               <li><a href="two.php">Tab2</a></li>
               <li><a href="three.php">Tab3</a></li>

The first issue is that you need to make sure that the end declaration for your heredoc -- EOD; -- is not indented at all. If it is indented, then you will get errors.

As for your issue with the PHP code not running within the heredoc statement, that is because you are looking at it wrong. Using a heredoc statement is not the same as closing the PHP tags. As such, you do not need to try reopening them. That will do nothing for you. The way the heredoc syntax works is that everything between the opening and closing is displayed exactly as written with the exception of variables. Those are replaced with the associated value. I removed your logic from the heredoc and used a tertiary function to determine the class to make this easier to see (though I don't believe any logical statements will work within the heredoc anyway)

To understand the heredoc syntax, it is the same as including it within double quotes ("), but without the need for escaping. So your code could also be written like this:

     $class = ($page == 'one') ? 'class="active"' : '';
     $nav = "<div id=\"nav\">
               <li><a $class href=\"index.php\">Tab1</a>/</li>
               <li><a href=\"two.php\">Tab2</a></li>
               <li><a href=\"three.php\">Tab3</a></li>

It will do exactly the same thing, just is written somewhat differently. Another difference between heredoc and the string is that you can escape out of the string in the middle where you can't in the heredoc. Using this logic, you can produce the following code:

     $nav = "<div id=\"nav\">
               <li><a ".(($page == 'one') ? 'class="active"' : '')." href=\"index.php\">Tab1</a>/</li>
               <li><a href=\"two.php\">Tab2</a></li>
               <li><a href=\"three.php\">Tab3</a></li>

Then you can include the logic directly in the string like you originally intended.

Whichever method you choose makes very little (if any) difference in the performance of the script. It mostly boils down to preference. Either way, you need to make sure you understand how each works.

Validate phone number using angular js

Try this:

<form class="form-horizontal" role="form" method="post" name="registration" novalidate>
    <div class="form-group" ng-class="{'has-error':$error.number}">
        <label for="inputPhone" class="col-sm-3 control-label">Phone :</label>
        <div class="col-sm-9">
            <input type="number" 
            <span class="help-block" 
                  ng-show="$error.required || 
                           Valid phone number is required
            <span class="help-block" 
                  ng-show="(($error.minlength ||
                 $error.maxlength) && 
                 $dirty) ">
                           phone number should be 10 digits

Step-by-step debugging with IPython

Running from inside Emacs' IPython-shell and breakpoint set via pdb.set_trace() should work.

Checked with python-mode.el, M-x ipython RET etc.

Finding the second highest number in array

int arr[] = {25, 5, 35, 26, 6, 270, 0};

int large1 = arr[0];
int large2 = arr[1];

for (int i = 2; i < arr.length; i++) {

    if (arr[i] > large1) {

        if (large1 > large2)
            large2 = large1;
        large1 = arr[i];

    } else if (arr[i] > large2)
        large2 = arr[i];                    

System.out.println("Large1 " + large1);
System.out.println("Large2 " + large2);

Xcode "Device Locked" When iPhone is unlocked

For anyone who need a logical answer..

  1. Go to Window -> Devices & Simulators. Right click on your device & unpair it.
  2. Disconnect from cable & reconnect.
  3. Wait for it & let Xcode detect you device.
  4. Run the project.
  5. Make sure you TRUST on your iOS device and enter any passcode.

Delete all records in a table of MYSQL in phpMyAdmin

An interesting fact.

I was sure TRUNCATE will always perform better, but in my case, for a db with approx 30 tables with foreign keys, populated with only a few rows, it took about 12 seconds to TRUNCATE all tables, as opposed to only a few hundred milliseconds to DELETE the rows. Setting the auto increment adds about a second in total, but it's still a lot better.

So I would suggest try both, see which works faster for your case.

In C#, should I use string.Empty or String.Empty or "" to intitialize a string?

While difference is very, VERY little, the difference still exist.

1) "" creates object while String.Empty does not. But this object will be created once and will be referenced from the string pool later if you have another "" in the code.

2) String and string are the same, but I would recommend to use String.Empty (as well as String.Format, String.Copy etc.) since dot notation indicates class, not operator, and having class starting with capital letter conforms to C# coding standards.

HTML Button : Navigate to Other Page - Different Approaches

I use method 3 because it's the most understandable for others (whenever you see an <a> tag, you know it's a link) and when you are part of a team, you have to make simple things ;).

And finally I don't think it's useful and efficient to use JS simply to navigate to an other page.

How to use bootstrap-theme.css with bootstrap 3?

First, bootstrap-theme.css is nothing else but equivalent of Bootstrap 2.x style in Bootstrap 3. If you really want to use it, just add it ALONG with bootstrap.css (minified version will work too).

What is the easiest way to parse an INI file in Java?

In 18 lines, extending the java.util.Properties to parse into multiple sections:

public static Map<String, Properties> parseINI(Reader reader) throws IOException {
    Map<String, Properties> result = new HashMap();
    new Properties() {

        private Properties section;

        public Object put(Object key, Object value) {
            String header = (((String) key) + " " + value).trim();
            if (header.startsWith("[") && header.endsWith("]"))
                return result.put(header.substring(1, header.length() - 1), 
                        section = new Properties());
                return section.put(key, value);

    return result;

Remove part of string in Java

Using StringUtils from commons lang

A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.

String str = StringUtils.remove("Test remove", "remove");
//result will be "Test"

Converting Secret Key into a String and Vice Versa

To show how much fun it is to create some functions that are fail fast I've written the following 3 functions.

One creates an AES key, one encodes it and one decodes it back. These three methods can be used with Java 8 (without dependence of internal classes or outside dependencies):

public static SecretKey generateAESKey(int keysize)
        throws InvalidParameterException {
    try {
        if (Cipher.getMaxAllowedKeyLength("AES") < keysize) {
            // this may be an issue if unlimited crypto is not installed
            throw new InvalidParameterException("Key size of " + keysize
                    + " not supported in this runtime");

        final KeyGenerator keyGen = KeyGenerator.getInstance("AES");
        return keyGen.generateKey();
    } catch (final NoSuchAlgorithmException e) {
        // AES functionality is a requirement for any Java SE runtime
        throw new IllegalStateException(
                "AES should always be present in a Java SE runtime", e);

public static SecretKey decodeBase64ToAESKey(final String encodedKey)
        throws IllegalArgumentException {
    try {
        // throws IllegalArgumentException - if src is not in valid Base64
        // scheme
        final byte[] keyData = Base64.getDecoder().decode(encodedKey);
        final int keysize = keyData.length * Byte.SIZE;

        // this should be checked by a SecretKeyFactory, but that doesn't exist for AES
        switch (keysize) {
        case 128:
        case 192:
        case 256:
            throw new IllegalArgumentException("Invalid key size for AES: " + keysize);

        if (Cipher.getMaxAllowedKeyLength("AES") < keysize) {
            // this may be an issue if unlimited crypto is not installed
            throw new IllegalArgumentException("Key size of " + keysize
                    + " not supported in this runtime");

        // throws IllegalArgumentException - if key is empty
        final SecretKeySpec aesKey = new SecretKeySpec(keyData, "AES");
        return aesKey;
    } catch (final NoSuchAlgorithmException e) {
        // AES functionality is a requirement for any Java SE runtime
        throw new IllegalStateException(
                "AES should always be present in a Java SE runtime", e);

public static String encodeAESKeyToBase64(final SecretKey aesKey)
        throws IllegalArgumentException {
    if (!aesKey.getAlgorithm().equalsIgnoreCase("AES")) {
        throw new IllegalArgumentException("Not an AES key");

    final byte[] keyData = aesKey.getEncoded();
    final String encodedKey = Base64.getEncoder().encodeToString(keyData);
    return encodedKey;

How could I create a list in c++?

You should really use the standard List class. Unless, of course, this is a homework question, or you want to know how lists are implemented by STL.

You'll find plenty of simple tutorials via google, like this one. If you want to know how linked lists work "under the hood", try searching for C list examples/tutorials rather than C++.

how to check if string value is in the Enum list?

You can use the Enum.TryParse method:

Age age;
if (Enum.TryParse<Age>("New_Born", out age))
    // You now have the value in age 

unable to install pg gem

For Mac Users

PATH=$PATH:/Library/PostgreSQL/9.4/bin/ gem install pg

This should do the trick

Extract Google Drive zip from Google colab notebook

TO unzip a file to a directory:

!unzip -d path_to_directory

Updating PartialView mvc 4

You can also try this.

 $(document).ready(function () {
            var url = "@(Html.Raw(Url.Action("ActionName", "ControllerName")))";
        setInterval(function () {
            var url = "@(Html.Raw(Url.Action("ActionName", "ControllerName")))";
        }, 30000); //Refreshes every 30 seconds

        $.ajaxSetup({ cache: false });  //Turn off caching

It makes an initial call to load the div, and then subsequent calls are on a 30 second interval.

In the controller section you can update the object and pass the object to the partial view.

public class ControllerName: Controller
    public ActionResult ActionName()
        .   // code for update object
        return PartialView("PartialViewName", updatedObject);

How to convert an int to a hex string?

Also you can convert any number in any base to hex. Use this one line code here it's easy and simple to use:


You have a string n that is your number and x the base of that number. First, change it to integer and then to hex but hex has 0x at the first of it so with replace we remove it.

SQL Server returns error "Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'." in Windows application

Got it! Solved the issue modifying the user properties in security session of SQL Server. In SQL Server Management, go into security -> Logon -> Choose the user used for DB connection and go into his properties. Go to "Securators" tab and look for line "Connect SQL", mark "Grant" option and take a try. It works for me!


How to have a a razor action link open in a new tab?

You are setting it't type as submit. That means that browser should post your <form> data to the server.

In fact a tag has no type attribute according to w3schools.

So remote type attribute and it should work for you.

How do I add multiple "NOT LIKE '%?%' in the WHERE clause of sqlite3?

The query you are after will be

SELECT word FROM table WHERE word NOT LIKE '%a%' AND word NOT LIKE '%b%'

Cannot execute RUN mkdir in a Dockerfile

Apart from the previous use cases, you can also use Docker Compose to create directories in case you want to make new dummy folders on docker-compose up:

  - .:/ftp/
  - /ftp/node_modules
  - /ftp/files

Syntax for a single-line Bash infinite while loop

A very simple infinite loop.. :)

while true ; do continue ; done

Fr your question it would be:

while true; do foo ; sleep 2 ; done

Syntax error due to using a reserved word as a table or column name in MySQL

The Problem

In MySQL, certain words like SELECT, INSERT, DELETE etc. are reserved words. Since they have a special meaning, MySQL treats it as a syntax error whenever you use them as a table name, column name, or other kind of identifier - unless you surround the identifier with backticks.

As noted in the official docs, in section 10.2 Schema Object Names (emphasis added):

Certain objects within MySQL, including database, table, index, column, alias, view, stored procedure, partition, tablespace, and other object names are known as identifiers.


If an identifier contains special characters or is a reserved word, you must quote it whenever you refer to it.


The identifier quote character is the backtick ("`"):

A complete list of keywords and reserved words can be found in section 10.3 Keywords and Reserved Words. In that page, words followed by "(R)" are reserved words. Some reserved words are listed below, including many that tend to cause this issue.

  • ADD
  • AND
  • BY
  • CALL
  • CASE
  • DESC
  • FROM
  • IN
  • IS
  • KEY
  • LIKE
  • LONG
  • NOT
  • OR
  • RANK
  • TO

The Solution

You have two options.

1. Don't use reserved words as identifiers

The simplest solution is simply to avoid using reserved words as identifiers. You can probably find another reasonable name for your column that is not a reserved word.

Doing this has a couple of advantages:

  • It eliminates the possibility that you or another developer using your database will accidentally write a syntax error due to forgetting - or not knowing - that a particular identifier is a reserved word. There are many reserved words in MySQL and most developers are unlikely to know all of them. By not using these words in the first place, you avoid leaving traps for yourself or future developers.

  • The means of quoting identifiers differs between SQL dialects. While MySQL uses backticks for quoting identifiers by default, ANSI-compliant SQL (and indeed MySQL in ANSI SQL mode, as noted here) uses double quotes for quoting identifiers. As such, queries that quote identifiers with backticks are less easily portable to other SQL dialects.

Purely for the sake of reducing the risk of future mistakes, this is usually a wiser course of action than backtick-quoting the identifier.

2. Use backticks

If renaming the table or column isn't possible, wrap the offending identifier in backticks (`) as described in the earlier quote from 10.2 Schema Object Names.

An example to demonstrate the usage (taken from 10.3 Keywords and Reserved Words):

mysql> CREATE TABLE interval (begin INT, end INT);
ERROR 1064 (42000): You have an error in your SQL syntax.
near 'interval (begin INT, end INT)'

mysql> CREATE TABLE `interval` (begin INT, end INT); Query OK, 0 rows affected (0.01 sec)

Similarly, the query from the question can be fixed by wrapping the keyword key in backticks, as shown below:

INSERT INTO user_details (username, location, `key`)
VALUES ('Tim', 'Florida', 42)";               ^   ^

How to check if a double value has no decimal part

either ceil and floor should give the same out out put

Math.ceil(x.y) == Math.floor(x.y)

or simply check for equality with double value

x.y == Math.ceil(x.y)
x.y == Math.floor(x.y)


Math.round(x.y) == x.y

How to store a datetime in MySQL with timezone info

All the symptoms you describe suggest that you never tell MySQL what time zone to use so it defaults to system's zone. Think about it: if all it has is '2011-03-13 02:49:10', how can it guess that it's a local Tanzanian date?

As far as I know, MySQL doesn't provide any syntax to specify time zone information in dates. You have to change it a per-connection basis; something like:

SET time_zone = 'EAT';

If this doesn't work (to use named zones you need that the server has been configured to do so and it's often not the case) you can use UTC offsets because Tanzania does not observe daylight saving time at the time of writing but of course it isn't the best option:

SET time_zone = '+03:00';

How to set an button align-right with Bootstrap?

<div class="container">
    <div class="btn-block pull-right">
        <a href="#" class="btn btn-primary pull-right">Search</a>
        <a href="#" class="btn btn-primary pull-right">Apple</a>
        <a href="#" class="btn btn-primary pull-right">Sony</a>

struct.error: unpack requires a string argument of length 4

By default, on many platforms the short will be aligned to an offset at a multiple of 2, so there will be a padding byte added after the char.

To disable this, use: struct.unpack("=BH", data). This will use standard alignment, which doesn't add padding:

>>> struct.calcsize('=BH')

The = character will use native byte ordering. You can also use < or > instead of = to force little-endian or big-endian byte ordering, respectively.

Find an element by class name, from a known parent element

var element = $("#parentDiv .myClassNameOfInterest")

Max size of URL parameters in _GET

See What is the maximum length of a URL in different browsers?

The length of the url can't be changed in PHP. The linked question is about the URL size limit, you will find what you want.

WCF service maxReceivedMessageSize basicHttpBinding issue

Removing the name from your binding will make it apply to all endpoints, and should produce the desired results. As so:

  <service name="Service.IService">
    <clear />
    <endpoint binding="basicHttpBinding" contract="Service.IService" />
    <binding maxBufferSize="2147483647" maxReceivedMessageSize="2147483647">
      <readerQuotas maxDepth="32" maxStringContentLength="2147483647"
        maxArrayLength="16348" maxBytesPerRead="4096" maxNameTableCharCount="16384" />
    <binding maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" />

Also note that I removed the bindingConfiguration attribute from the endpoint node. Otherwise you would get an exception.

This same solution was found here : Problem with large requests in WCF

How do I share variables between different .c files?

  1. Try to avoid globals. If you must use a global, see the other answers.
  2. Pass it as an argument to a function.

Set ImageView width and height programmatically?

image.setLayoutParams(new ViewGroup.LayoutParams(width, height));


image.setLayoutParams(new ViewGroup.LayoutParams(150, 150));

How do I replace part of a string in PHP?

You need first to cut the string in how many pieces you want. Then replace the part that you want:

 $text = 'this is the test for string.';
 $text = substr($text, 0, 10);
 echo $text = str_replace(" ", "_", $text);

This will output:


Iterating C++ vector from the end to the beginning

If you have C++11 you can make use of auto.

for (auto it = my_vector.rbegin(); it != my_vector.rend(); ++it)

Chrome javascript debugger breakpoints don't do anything?

I'm not sure how it worked, but hitting F1 for settings and at the bottom right, hitting "Restore defaults and reload" worked for me.

Uncaught ReferenceError: angular is not defined - AngularJS not working

Just to complement m59's correct answer, here is a working jsfiddle:

<body ng-app='myApp'>
        <button my-directive>Click Me!</button>


Is there any way to show a countdown on the lockscreen of iphone?

There is no way to display interactive elements on the lockscreen or wallpaper with a non jailbroken iPhone.

I would recommend Countdown Widget it's free an you can display countdowns in the notification center which you can also access from your lockscreen.

Keep placeholder text in UITextField on input in IOS

Instead of using the placeholder text, you'll want to set the actual text property of the field to MM/YYYY, set the delegate of the text field and listen for this method:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {     // update the text of the label } 

Inside that method, you can figure out what the user has typed as they type, which will allow you to update the label accordingly.

Is it possible to Turn page programmatically in UIPageViewController?

For single page, I just edited the answer of @Jack Humphries

  counter = 0;
  DataViewController *secondVC = [self.modelController viewControllerAtIndex:counter storyboard:self.storyboard];
  NSArray *viewControllers = nil;          
  viewControllers = [NSArray arrayWithObjects:secondVC, nil];          
  [self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:NULL];

Enable 'xp_cmdshell' SQL Server

While the accepted answer will work most of the times, I have encountered (still do not know why) some cases that is does not. A slight modification of the query by using the WITH OVERRIDE in RECONFIGURE gives the solution

Use Master

EXEC master.dbo.sp_configure 'show advanced options', 1

EXEC master.dbo.sp_configure 'xp_cmdshell', 1

The expected output is

Configuration option 'show advanced options' changed from 0 to 1. Run the RECONFIGURE statement to install.
Configuration option 'xp_cmdshell' changed from 0 to 1. Run the RECONFIGURE statement to install.

How to set xampp open localhost:8080 instead of just localhost

Steps using XAMPP GUI:

Step-1: Click on Config button

enter image description here

Step-2: Click on Service and Port Settings button

enter image description here

Final step: Change your port and Save

enter image description here

Google access token expiration time

The spec says seconds:

    OPTIONAL.  The lifetime in seconds of the access token.  For
    example, the value "3600" denotes that the access token will
    expire in one hour from the time the response was generated.

I agree with OP that it's careless for Google to not document this.

How to convert a string to lower case in Bash?

Many answers using external programs, which is not really using Bash.

If you know you will have Bash4 available you should really just use the ${VAR,,} notation (it is easy and cool). For Bash before 4 (My Mac still uses Bash 3.2 for example). I used the corrected version of @ghostdog74 's answer to create a more portable version.

One you can call lowercase 'my STRING' and get a lowercase version. I read comments about setting the result to a var, but that is not really portable in Bash, since we can't return strings. Printing it is the best solution. Easy to capture with something like var="$(lowercase $str)".

How this works

The way this works is by getting the ASCII integer representation of each char with printf and then adding 32 if upper-to->lower, or subtracting 32 if lower-to->upper. Then use printf again to convert the number back to a char. From 'A' -to-> 'a' we have a difference of 32 chars.

Using printf to explain:

$ printf "%d\n" "'a"
$ printf "%d\n" "'A"

97 - 65 = 32

And this is the working version with examples.
Please note the comments in the code, as they explain a lot of stuff:



# Prints the lowercase version of a char
    case "$1" in
            n=$(printf "%d" "'$1")
            printf \\$(printf "%o" "$n")
            printf "%s" "$1"

# Prints the lowercase version of a sequence of strings
lowercase() {
    for((i=0;i<${#word};i++)); do
        lowercaseChar "$ch"

# Prints the uppercase version of a char
    case "$1" in
            n=$(printf "%d" "'$1")
            printf \\$(printf "%o" "$n")
            printf "%s" "$1"

# Prints the uppercase version of a sequence of strings
uppercase() {
    for((i=0;i<${#word};i++)); do
        uppercaseChar "$ch"

# The functions will not add a new line, so use echo or
# append it if you want a new line after printing

# Printing stuff directly
lowercase "I AM the Walrus!"$'\n'
uppercase "I AM the Walrus!"$'\n'

echo "----------"

# Printing a var
str="A StRing WITH mixed sTUFF!"
lowercase "$str"$'\n'
uppercase "$str"$'\n'

echo "----------"

# Not quoting the var should also work, 
# since we use "$@" inside the functions
lowercase $str$'\n'
uppercase $str$'\n'

echo "----------"

# Assigning to a var
myLowerVar="$(lowercase $str)"
myUpperVar="$(uppercase $str)"
echo "myLowerVar: $myLowerVar"
echo "myUpperVar: $myUpperVar"

echo "----------"

# You can even do stuff like
if [[ 'option 2' = "$(lowercase 'OPTION 2')" ]]; then
    echo "Fine! All the same!"
    echo "Ops! Not the same!"

exit 0

And the results after running this:

$ ./ 
i am the walrus!
a string with mixed stuff!
a string with mixed stuff!
myLowerVar: a string with mixed stuff!
Fine! All the same!

This should only work for ASCII characters though.

For me it is fine, since I know I will only pass ASCII chars to it.
I am using this for some case-insensitive CLI options, for example.

display Java.util.Date in a specific format

It makes no sense, but:


SimpleDateFormat.parse() = // parse Date from String
SimpleDateFormat.format() = // format Date into String

How do you run multiple programs in parallel from a bash script?

prog1 & 2> .errorprog1.log; prog2 & 2> .errorprog2.log

Redirect errors to separate logs.

Simulation of CONNECT BY PRIOR of Oracle in SQL Server

The SQL standard way to implement recursive queries, as implemented e.g. by IBM DB2 and SQL Server, is the WITH clause. See this article for one example of translating a CONNECT BY into a WITH (technically a recursive CTE) -- the example is for DB2 but I believe it will work on SQL Server as well.

Edit: apparently the original querant requires a specific example, here's one from the IBM site whose URL I already gave. Given a table:

                 name   VARCHAR(10),
                 salary DECIMAL(9, 2),
                 mgrid  INTEGER);

where mgrid references an employee's manager's empid, the task is, get the names of everybody who reports directly or indirectly to Joan. In Oracle, that's a simple CONNECT:

SELECT name 
  FROM emp
  START WITH name = 'Joan'
  CONNECT BY PRIOR empid = mgrid

In SQL Server, IBM DB2, or PostgreSQL 8.4 (as well as in the SQL standard, for what that's worth;-), the perfectly equivalent solution is instead a recursive query (more complex syntax, but, actually, even more power and flexibility):

WITH n(empid, name) AS 
   (SELECT empid, name 
    FROM emp
    WHERE name = 'Joan'
        UNION ALL
    SELECT nplus1.empid, 
    FROM emp as nplus1, n
    WHERE n.empid = nplus1.mgrid)

Oracle's START WITH clause becomes the first nested SELECT, the base case of the recursion, to be UNIONed with the recursive part which is just another SELECT.

SQL Server's specific flavor of WITH is of course documented on MSDN, which also gives guidelines and limitations for using this keyword, as well as several examples.

Is it possible to run one logrotate check manually?

Created a shell script to solve the problem.

This script will run just the single logrotate sub-configuration file found in "/etc/logrotate.d", but include the global settings from in the global configuration file "/etc/logrotate.conf". You can also use other otpions for testing it...

For example...

  logrotate_one -d syslog

kill a process in bash

Please check "top" command then if your script or any are running please note 'PID'

 1384 root      20   0  514m  32m 2188 S  0.3  5.4  55:09.88 example
14490 root      20   0 15140 1216  920 R  0.3  0.2   0:00.02 example2

kill <you process ID>

Example : kill 1384

excel plot against a date time x series

You will need to specify TimeSeries in Excel to be plotted. Have a look at this

Plotting Time Series