Programs & Examples On #Dof file

How to get the current working directory in Java?

Use CodeSource#getLocation().

This works fine in JAR files as well. You can obtain CodeSource by ProtectionDomain#getCodeSource() and the ProtectionDomain in turn can be obtained by Class#getProtectionDomain().

public class Test {
    public static void main(String... args) throws Exception {
        URL location = Test.class.getProtectionDomain().getCodeSource().getLocation();

php search array key and get value


// Checks if key exists (doesn't care about it's value).
// @link
if (array_key_exists(20120504, $search_array)) {
  echo $search_array[20120504];

// Checks against NULL
// @link
if (isset($search_array[20120504])) {
  echo $search_array[20120504];

// No warning or error if key doesn't exist plus checks for emptiness.
// @link
if (!empty($search_array[20120504])) {
  echo $search_array[20120504];


'Syntax Error: invalid syntax' for no apparent reason

I encountered a similar problem, with a syntax error that I knew should not be a syntax error. In my case it turned out that a Python 2 interpreter was trying to run Python 3 code, or vice versa; I think that my shell had a PYTHONPATH with a mixture of Python 2 and Python 3.

Struct Constructor in C++?

Yes structures and classes in C++ are the same except that structures members are public by default whereas classes members are private by default. Anything you can do in a class you should be able to do in a structure.

struct Foo
    // Initialize Foo

MySQL Workbench: How to keep the connection alive

In 5.2.47 (at least on mac), go the location of the preferences is: MySQLWorkbench->Preferences->SQL Editor

Then you'll see both:

DBMS connection keep-alive interval (in seconds): DBMS connection read time out (in seconds):

The latter is where you'll want to up the limit from 600 to something a bit more.

Margin-Top not working for span element?

span element is display:inline; by default you need to make it inline-block or block

Change your CSS to be like this

span.first_title {
    margin-top: 20px;
    margin-left: 12px;
    font-weight: bold;
    color: #221461;
    /*The change*/
    display:inline-block; /*or display:block;*/

How to convert ‘false’ to 0 and ‘true’ to 1 in Python

If B is a Boolean array, write

B = B*1

(A bit code golfy.)

Bootstrap 3 Navbar with Logo

Please try following code:

   .navbar a.navbar-brand {padding: 9px 15px 8px; }
<a class="navbar-brand" href="#">
   <img src=";text=LOGO" alt="">

View RDD contents in Python Spark?

You can simply collect the entire RDD (which will return a list of rows) and print said list:


Server configuration is missing in Eclipse

As Yoni already mentioned, you probably deleted the project named "Servers" from your Project Explorer. If config files for the server still present on a file system, the quickest way to restore it will be Right Click in Project Explorer->Import->General->Existing Projects into Workspace, then select the root dir where Servers dir located, set checkbox near "Servers" and finally click Finish. If everything works as expected, you should see the 'Servers' project added to the Project Explorer view and your old config files will be there. Finally, save the tomcat configuration which you had open. You can startup your Tomcat server without errors now.

PowerShell Remoting giving "Access is Denied" error

Running the command prompt or Powershell ISE as an administrator fixed this for me.

Calling one method from another within same class in Python

To accessing member functions or variables from one scope to another scope (In your case one method to another method we need to refer method or variable with class object. and you can do it by referring with self keyword which refer as class object.

class YourClass():

    def your_function(self, *args):

        self.callable_function(param) # if you need to pass any parameter

    def callable_function(self, *params): 
        print('Your param:', param)

Simplest/cleanest way to implement a singleton in JavaScript

My two cents: I have a constructor function (CF), for example,

var A = function(arg1){
  this.arg1 = arg1

I need just every object created by this CF to be the same.

var X = function(){
  var instance = {};
  return function(){ return instance; }


var x1 = new X();
var x2 = new X();
console.log(x1 === x2)

Best C++ IDE or Editor for Windows

I think the debugger in Visual Studio (Express) is the killer thing that prevents me from using another IDE.

disable editing default value of text input

I'm not sure I understand the question correctly, but if you want to prevent people from writing in the input field you can use the disabled attribute.

<input disabled="disabled" id="price_from" value="price from ">

WSDL/SOAP Test With soapui

I faced the same exception while trying to test my web-services deployed to WSO2 ESB.

WSO2 generated both wsdl and wsdl2. I tried to pass a wsdl2 URL and got the above exception. Quick googling showed me, that one of differences between wsdl1.1 and wsdl2.0 is replacing 'definitions' element with 'description'. Also, I found out, that SoapUI does not support wsdl2.

Therefore, for me the solution was to use wsdl1 url instead of wsdl2.

Can I have multiple primary keys in a single table?

This is the answer for both the main question and for @Kalmi's question of

What would be the point of having multiple auto-generating columns?

This code below has a composite primary key. One of its columns is auto-incremented. This will work only in MyISAM. InnoDB will generate an error "ERROR 1075 (42000): Incorrect table definition; there can be only one auto column and it must be defined as a key".

DROP TABLE IF EXISTS `test`.`animals`;
CREATE TABLE  `test`.`animals` (
  `grp` char(30) NOT NULL,
  `id` mediumint(9) NOT NULL AUTO_INCREMENT,
  `name` char(30) NOT NULL,
  PRIMARY KEY (`grp`,`id`)

INSERT INTO animals (grp,name) VALUES

SELECT * FROM animals ORDER BY grp,id;

Which returns:

| grp    | id | name    |
| fish   |  1 | lax     |
| mammal |  1 | dog     |
| mammal |  2 | cat     |
| mammal |  3 | whale   |
| bird   |  1 | penguin |
| bird   |  2 | ostrich |

Failed binder transaction when putting an bitmap dynamically in a widget

I have solved this issue by storing images on internal storage and then using .setImageURI() rather than .setBitmap().

Similarity String Comparison in Java

Yes, there are many well documented algorithms like:

  • Cosine similarity
  • Jaccard similarity
  • Dice's coefficient
  • Matching similarity
  • Overlap similarity
  • etc etc

A good summary ("Sam's String Metrics") can be found here (original link dead, so it links to Internet Archive)

Also check these projects:

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

I've hade the same problem. I resolved with

git checkout <name branch>
git pull origin <name branch>
git push origin <name branch>

How to upgrade docker container after its image changed

This is something I've also been struggling with for my own images. I have a server environment from which I create a Docker image. When I update the server, I'd like all users who are running containers based on my Docker image to be able to upgrade to the latest server.

Ideally, I'd prefer to generate a new version of the Docker image and have all containers based on a previous version of that image automagically update to the new image "in place." But this mechanism doesn't seem to exist.

So the next best design I've been able to come up with so far is to provide a way to have the container update itself--similar to how a desktop application checks for updates and then upgrades itself. In my case, this will probably mean crafting a script that involves Git pulls from a well-known tag.

The image/container doesn't actually change, but the "internals" of that container change. You could imagine doing the same with apt-get, yum, or whatever is appropriate for you environment. Along with this, I'd update the myserver:latest image in the registry so any new containers would be based on the latest image.

I'd be interested in hearing whether there is any prior art that addresses this scenario.

jQuery Set Select Index


$('#selectBox option')[3].attr('selected', 'selected') 

is incorrect, the array deference gets you the dom object, not a jquery object, so it will fail with a TypeError, for instance in FF with: "$('#selectBox option')[3].attr() not a function."

Protractor : How to wait for page complete after click a button?

In this case, you can used:

Page Object:

    waitForURLContain(urlExpected: string, timeout: number) {
        try {
            const condition = browser.ExpectedConditions;
            browser.wait(condition.urlContains(urlExpected), timeout);
        } catch (e) {
            console.error('URL not contain text.', e);

Page Test:

page.waitForURLContain('abc#/efg', 30000);

Cannot find mysql.sock

This found it for me:

netstat -ln | grep mysql


Collapse all methods in Visual Studio Code

Ctrl+K, Ctrl+1 and then Ctrl+K, Ctrl+2 will do close to what you want.

The first command collapses level 1 (usually classes), and the second command collapses level 2 (usually methods).

You might even find it useful to skip the first command.

JDK on OSX 10.7 Lion

I have just ran into the same problem after updating. The JRE that is downloaded by OSX Lion is missing JavaRuntimeSupport.jar which will work but can wreck havoc on a lot of things. If you've updated, and you had a working JDK/JRE installed prior to that, do the following in Eclipse:

1) Project > Properties > Java Build Path > Select broken JRE/JDK > Edit

2) Select "Alternate JRE"

3) Click "Installed JREs..."

4) In the window that opens, click "Search..."

If all goes well, it will find your older JRE/JDK. Mine was in this location:


Removing numbers from string

I'd love to use regex to accomplish this, but since you can only use lists, loops, functions, etc..

here's what I came up with:

stringWithNumbers="I have 10 bananas for my 5 monkeys!"
stringWithoutNumbers=''.join(c if c not in map(str,range(0,10)) else "" for c in stringWithNumbers)
print(stringWithoutNumbers) #I have  bananas for my  monkeys!

How to kill/stop a long SQL query immediately?

sp_who2 'active'

Check values under CPUTime and DiskIO. Note the SPID of process having large value comparatively.

kill {SPID value}

IIS: Where can I find the IIS logs?


Check the identity of the site going to sites and advanced settings

How to create UILabel programmatically using Swift?

Swift 4.2 and Xcode 10 Initialize label before viewDidLoad.

lazy var topLeftLabel: UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.text = "TopLeft"
    return label

In viewDidLoad add label to the view and apply constraints.

override func viewDidLoad() {
    topLeftLabel.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 10).isActive = true
    topLeftLabel.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 10).isActive = true

How to Delete a directory from Hadoop cluster which is having comma(,) in its name?

Or if you dont know the url, you can use

hadoop fs -rm -r -f /user/the/path/to/your/dir

How to set data attributes in HTML elements

Vanilla Javascript solution


<div id="mydiv" data-myval="10"></div>


  • Using DOM's getAttribute() property

     var brand = mydiv.getAttribute("data-myval")//returns "10"
     mydiv.setAttribute("data-myval", "20")      //changes "data-myval" to "20"
     mydiv.removeAttribute("data-myval")         //removes "data-myval" attribute entirely
  • Using JavaScript's dataset property

    var myval = mydiv.dataset.myval     //returns "10"
    mydiv.dataset.myval = '20'          //changes "data-myval" to "20"
    mydiv.dataset.myval = null          //removes "data-myval" attribute

IndexError: tuple index out of range ----- Python

A tuple consists of a number of values separated by commas. like

>>> t = 12345, 54321, 'hello!'
>>> t[0]

tuple are index based (and also immutable) in Python.

Here in this case x = rows[1][1] + " " + rows[1][2] have only two index 0, 1 available but you are trying to access the 3rd index.

How to create Custom Ratings bar in Android

For SVG RatingBar I used RatingBar custom Vector Drawables superimposing and the answer of erdomester here. This solution traverses all drawables inside SvgRatingBar view of your layout, so in RecyclerView it has an overhead.

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Build;
import android.util.AttributeSet;
import android.view.Gravity;


import com.example.R; // Your file for R.attr.ratingBarStyle.

public class SvgRatingBar extends androidx.appcompat.widget.AppCompatRatingBar {

    private Bitmap sampleTile;

    public SvgRatingBar(Context context) {
        this(context, null);

    public SvgRatingBar(Context context, AttributeSet attrs) {
        this(context, attrs, R.attr.ratingBarStyle);

    public SvgRatingBar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

    private void init() {
        LayerDrawable drawable = (LayerDrawable) createTile(getProgressDrawable(), false);

     * Converts a drawable to a tiled version of itself. It will recursively
     * traverse layer and state list drawables.
    private Drawable createTile(Drawable drawable, boolean clip) {
        if (drawable instanceof DrawableWrapper) {
            Drawable inner = ((DrawableWrapper) drawable).getWrappedDrawable();
            if (inner != null) {
                inner = createTile(inner, clip);
                ((DrawableWrapper) drawable).setWrappedDrawable(inner);
        } else if (drawable instanceof LayerDrawable) {
            LayerDrawable background = (LayerDrawable) drawable;
            final int n = background.getNumberOfLayers();
            Drawable[] outDrawables = new Drawable[n];

            for (int i = 0; i < n; i++) {
                int id = background.getId(i);
                outDrawables[i] = createTile(background.getDrawable(i),
                        (id == || id ==;
            LayerDrawable newBg = new LayerDrawable(outDrawables);

            for (int i = 0; i < n; i++) {
                newBg.setId(i, background.getId(i));

            return newBg;

        } else if (drawable instanceof BitmapDrawable) {
            final BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
            final Bitmap tileBitmap = bitmapDrawable.getBitmap();
            if (sampleTile == null) {
                sampleTile = tileBitmap;

            final ShapeDrawable shapeDrawable = new ShapeDrawable(getDrawableShape());
            final BitmapShader bitmapShader = new BitmapShader(tileBitmap,
                    Shader.TileMode.REPEAT, Shader.TileMode.CLAMP);
            return (clip) ? new ClipDrawable(shapeDrawable, Gravity.START,
                    ClipDrawable.HORIZONTAL) : shapeDrawable;
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && drawable instanceof VectorDrawable) {
            return createTile(getBitmapDrawableFromVectorDrawable(drawable), clip);
        } else if (drawable instanceof VectorDrawableCompat) {
            // API 19 support.
            return createTile(getBitmapDrawableFromVectorDrawable(drawable), clip);
        return drawable;

    private BitmapDrawable getBitmapDrawableFromVectorDrawable(Drawable drawable) {
        Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
        return new BitmapDrawable(getResources(), bitmap);

    protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (sampleTile != null) {
            final int width = sampleTile.getWidth() * getNumStars();
            setMeasuredDimension(resolveSizeAndState(width, widthMeasureSpec, 0),

    private Shape getDrawableShape() {
        final float[] roundedCorners = new float[]{5, 5, 5, 5, 5, 5, 5, 5};
        return new RoundRectShape(roundedCorners, null, null);

In your layout:


You also have to create rating_bar.xml with two SVG drawables:

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="">




enter image description here

If you see in Design/Split view only one star, refresh layout:

enter image description here

In Kotlin.

import android.annotation.SuppressLint
import android.content.Context
import android.os.Build
import android.util.AttributeSet
import android.view.Gravity
import androidx.appcompat.widget.AppCompatRatingBar
import com.example.R; // Your file for R.attr.ratingBarStyle.

class SvgRatingBar @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null,
                                             defStyleAttr: Int = R.attr.ratingBarStyle) :
    AppCompatRatingBar(context, attrs, defStyleAttr) {

    private var sampleTile: Bitmap? = null
    private val roundedCorners = floatArrayOf(5f, 5f, 5f, 5f, 5f, 5f, 5f, 5f)
    private val roundRectShape = RoundRectShape(roundedCorners, null, null)

    init {
        progressDrawable = createTile(progressDrawable, false) as LayerDrawable

     * Converts a drawable to a tiled version of itself. It will recursively
     * traverse layer and state list drawables.
    private fun createTile(drawable: Drawable, clip: Boolean): Drawable =
        when {
            drawable is DrawableWrapper -> {
                var inner = drawable.wrappedDrawable
                if (inner != null) {
                    inner = createTile(inner, clip)
                    drawable.wrappedDrawable = inner
            drawable is LayerDrawable -> {
                val n = drawable.numberOfLayers
                val outDrawables = arrayOfNulls<Drawable>(n)
                for (i in 0 until n) {
                    val id = drawable.getId(i)
                    outDrawables[i] = createTile(drawable.getDrawable(i),
                        id == || id ==
                val newBg = LayerDrawable(outDrawables)
                for (i in 0 until n) {
                    newBg.setId(i, drawable.getId(i))
            drawable is BitmapDrawable -> {
                val tileBitmap = drawable.bitmap
                if (sampleTile == null) {
                    sampleTile = tileBitmap
                val bitmapShader = BitmapShader(tileBitmap, Shader.TileMode.REPEAT,
                val shapeDrawable = ShapeDrawable(roundRectShape).apply {
                    paint.shader = bitmapShader
                    paint.colorFilter = drawable.paint.colorFilter
                if (clip) ClipDrawable(shapeDrawable, Gravity.START, ClipDrawable.HORIZONTAL)
                else shapeDrawable
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP && drawable is VectorDrawable -> {
                createTile(getBitmapDrawableFromVectorDrawable(drawable), clip)
            drawable is VectorDrawableCompat -> {
                // Pre-Lollipop support.
                createTile(getBitmapDrawableFromVectorDrawable(drawable), clip)
            else -> drawable

    private fun getBitmapDrawableFromVectorDrawable(drawable: Drawable): BitmapDrawable {
        val bitmap = Bitmap.createBitmap(drawable.intrinsicWidth, drawable.intrinsicHeight,
        val canvas = Canvas(bitmap)
        drawable.setBounds(0, 0, canvas.width, canvas.height)
        return BitmapDrawable(resources, bitmap)

    @Synchronized override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        if (sampleTile != null) {
            val width = sampleTile!!.width * numStars
            setMeasuredDimension(resolveSizeAndState(width, widthMeasureSpec, 0),

How to make an ng-click event conditional?

It is not good to manipulate with DOM (including checking of attributes) in any place except directives. You can add into scope some value indicating if link should be disabled.

But other problem is that ngDisabled does not work on anything except form controls, so you can't use it with <a>, but you can use it with <button> and style it as link.

Another way is to use lazy evaluation of expressions like isDisabled || action() so action wouold not be called if isDisabled is true.

Here goes both solutions:

Dynamically updating plot in matplotlib

In order to do this without FuncAnimation (eg you want to execute other parts of the code while the plot is being produced or you want to be updating several plots at the same time), calling draw alone does not produce the plot (at least with the qt backend).

The following works for me:

import matplotlib.pyplot as plt
class DynamicUpdate():
    #Suppose we know the x range
    min_x = 0
    max_x = 10

    def on_launch(self):
        #Set up plot
        self.figure, = plt.subplots()
        self.lines, =[],[], 'o')
        #Autoscale on unknown axis and known lims on the other, self.max_x)
        #Other stuff

    def on_running(self, xdata, ydata):
        #Update data (with the new _and_ the old points)
        #Need both of these in order to rescale
        #We need to draw *and* flush

    def __call__(self):
        import numpy as np
        import time
        xdata = []
        ydata = []
        for x in np.arange(0,10,0.5):
            self.on_running(xdata, ydata)
        return xdata, ydata

d = DynamicUpdate()

MySQL Like multiple values

Faster way of doing this:

WHERE interests LIKE '%sports%' OR interests LIKE '%pub%'

is this:

WHERE interests REGEXP 'sports|pub'

Found this solution here:,392332,392950#msg-392950

More about REGEXP here:

Escape sequence \f - form feed - what exactly is it?

From wiki page

12 (form feed, \f, ^L), to cause a printer to eject paper to the top of the next page, or a video terminal to clear the screen.

or more details here.

It seems that this symbol is rather obsolete now and the way it is processed may be(?) implementation dependent. At least for me your code gives the following output (xcode gcc 4.2, gdb console):


How to dynamically load a Python class

Here is to share something I found on __import__ and importlib while trying to solve this problem.

I am using Python 3.7.3.

When I try to get to the class d in module a.b.c,

mod = __import__('a.b.c')

The mod variable refer to the top namespace a.

So to get to the class d, I need to

mod = getattr(mod, 'b') #mod is now module b
mod = getattr(mod, 'c') #mod is now module c
mod = getattr(mod, 'd') #mod is now class d

If we try to do

mod = __import__('a.b.c')
d = getattr(mod, 'd')

we are actually trying to look for a.d.

When using importlib, I suppose the library has done the recursive getattr for us. So, when we use importlib.import_module, we actually get a handle on the deepest module.

mod = importlib.import_module('a.b.c') #mod is module c
d = getattr(mod, 'd') #this is a.b.c.d

Checking if a worksheet-based checkbox is checked

Building on the previous answers, you can leverage the fact that True is -1 and False is 0 and shorten your code like this:

Sub Button167_Click()
  Range("Y12").Value = _
    Abs(Worksheets(1).Shapes("Check Box 1").OLEFormat.Object.Value > 0)
End Sub

If the checkbox is checked, .Value = 1.

Worksheets(1).Shapes("Check Box 1").OLEFormat.Object.Value > 0 returns True.

Applying the Abs function converts True to 1.

If the checkbox is unchecked, .Value = -4146.

Worksheets(1).Shapes("Check Box 1").OLEFormat.Object.Value > 0 returns False.

Applying the Abs function converts False to 0.

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

Use dict.has_key() if (and only if) your code is required to be runnable by Python versions earlier than 2.3 (when key in dict was introduced).

Laravel Eloquent update just if changes have been made

I like to add this method, if you are using an edit form, you can use this code to save the changes in your update(Request $request, $id) function:

$post = Post::find($id);    

keep in mind that you have to name your inputs with the same column name. The fill() function will do all the work for you :)

How to calculate cumulative normal distribution?

Taken from above:

from scipy.stats import norm
>>> norm.cdf(1.96)
>>> norm.cdf(-1.96)

For a two-tailed test:

Import numpy as np
z = 1.96
p_value = 2 * norm.cdf(-np.abs(z))

How exactly does the android:onClick XML attribute differ from setOnClickListener?

Another way to set your on click listeners would be to use XML. Just add android:onClick attribute to your tag.

It is a good practice to use the xml attribute “onClick” over an anonymous Java class whenever possible.

First of all, lets have a look at the difference in code:

XML Attribute / onClick attribute

XML portion


Java portion

public void showToast(View v) {
    //Add some logic

Anonymous Java Class / setOnClickListener

XML Portion


Java portion

    new View.OnClickListener() {
        public void onClick(View v) {
            //Add some logic

Here are the benefits of using the XML attribute over an anonymous Java class:

  • With Anonymous Java class we always have to specify an id for our elements, but with XML attribute id can be omitted.
  • With Anonymous Java class we have to actively search for the element inside of the view (findViewById portion), but with the XML attribute Android does it for us.
  • Anonymous Java class requires at least 5 lines of code, as we can see, but with the XML attribute 3 lines of code is sufficient.
  • With Anonymous Java class we have to name of our method “onClick", but with the XML attribute we can add any name we want, which will dramatically help with the readability of our code.
  • Xml “onClick” attribute has been added by Google during the API level 4 release, which means that it is a bit more modern syntax and modern syntax is almost always better.

Of course, it is not always possible to use the Xml attribute, here are the reasons why we wouldn’t chose it:

  • If we are working with fragments. onClick attribute can only be added to an activity, so if we have a fragment, we would have to use an anonymous class.
  • If we would like to move the onClick listener to a separate class (maybe if it is very complicated and/or we would like to re-use it in different parts of our application), then we wouldn’t want to use the xml attribute either.

Is there any option to limit mongodb memory usage?

Adding to the top voted answer, in case you are on a low memory machine and want to configure the wiredTigerCache in MBs instead of whole number GBs, use this -

    configString : cache_size=345M

Source -

HTTP Error 404.3-Not Found in IIS 7.5

In my case, along with Mekanik's suggestions, I was receiving this error in Windows Server 2012 and I had to tick "HTTP Activation" in "Add Role Services".

How can I check the size of a file in a Windows batch script?

You'll need two things.


@echo off
echo %~z1

And then what you're actually trying to size up.

Copy a file only if it's larger than zero / copy only a non-zero file

for /f %i in ('filesize filesize.bat') do set z=%i
if %z% gtr 0 ( copy filesize.bat noodles.bat )

I found this thread and it was almost what I needed, I tried a bunch of different things - this was mildly frustrating because robocopy looked to have /min:1 but got ALL bunged up because I wanted to rename the file in transit which made me have to use @#$!! batch script.

Python socket.error: [Errno 111] Connection refused

The problem obviously was (as you figured it out) that port 36250 wasn't open on the server side at the time you tried to connect (hence connection refused). I can see the server was supposed to open this socket after receiving SEND command on another connection, but it apparently was "not opening [it] up in sync with the client side".

Well, the main reason would be there was no synchronisation whatsoever. Calling:

cs.send("SEND " + FILE)

would just place the data into a OS buffer; close would probably flush the data and push into the network, but it would almost certainly return before the data would reach the server. Adding sleep after close might mitigate the problem, but this is not synchronisation.

The correct solution would be to make sure the server has opened the connection. This would require server sending you some message back (for example OK, or better PORT 36250 to indicate where to connect). This would make sure the server is already listening.

The other thing is you must check the return values of send to make sure how many bytes was taken from your buffer. Or use sendall.

(Sorry for disturbing with this late answer, but I found this to be a high traffic question and I really didn't like the sleep idea in the comments section.)

Difference between Statement and PreparedStatement

Some of the benefits of PreparedStatement over Statement are:

  1. PreparedStatement helps us in preventing SQL injection attacks because it automatically escapes the special characters.
  2. PreparedStatement allows us to execute dynamic queries with parameter inputs.
  3. PreparedStatement provides different types of setter methods to set the input parameters for the query.
  4. PreparedStatement is faster than Statement. It becomes more visible when we reuse the PreparedStatement or use it’s batch processing methods for executing multiple queries.
  5. PreparedStatement helps us in writing object Oriented code with setter methods whereas with Statement we have to use String Concatenation to create the query. If there are multiple parameters to set, writing Query using String concatenation looks very ugly and error prone.

Read more about SQL injection issue at

Bootstrap fixed header and footer with scrolling body-content area in fluid-container

Until I get a better option, this is the most "bootstrappy" answer I can work out:


I have switched to using LESS and including the Bootstrap Source NuGet package to ensure compatibility (by giving me access to the bootstrap variables.less file:

in _layout.cshtml master page

  • Move footer outside the body-content container
  • Use boostrap's navbar-fixed-bottom on the footer
  • Drop the <hr/> before the footer (as now redundant)

Relevant page HTML:

<div class="container-fluid body-content">
<footer class="navbar-fixed-bottom">
    <p>&copy; @DateTime.Now.Year - My ASP.NET Application</p>

In Site.less

  • Set HTML and BODY heights to 100%
  • Set BODY overflow to hidden
  • Set body-content div position to absolute
  • Set body-content div top to @navbar-height instead of hard-wiring value
  • Set body-content div bottom to 30px.
  • Set body-content div left and right to 0
  • Set body-content div overflow-y to auto


html {
    height: 100%;

    body {
        height: 100%;
        overflow: hidden;

        .container-fluid.body-content {
            position: absolute;
            top: @navbar-height;
            bottom: 30px;
            right: 0;
            left: 0;
            overflow-y: auto;

The remaining problem is there seems to be no defining variable for the footer height in bootstrap. If someone call tell me if there is a magic 30px variable defined in Bootstrap I would appreciate it.

Is there a vr (vertical rule) in html?

How about:


Where top->bottom, right->left?

We will need vertical rule for this.

How do I implement IEnumerable<T>

make mylist into a List<MyObject>, is one option

apache redirect from non www to www

The code I use is:

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^www\.(.*)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

C#: How to access an Excel cell?


Excel.Application oXL;
Excel._Workbook oWB;
Excel._Worksheet oSheet;
Excel.Range oRng;

oXL = new Excel.Application();
oXL.Visible = true;
oWB = (Excel._Workbook)(oXL.Workbooks.Add(Missing.Value));

oSheet = (Excel._Worksheet)oWB.Worksheets;

oSheet.Cells[3, 9] = "Some Text"

What is the cleanest way to disable CSS transition effects temporarily?

This is the workaround that worked easily for me. It isn't direct answer to the question but still may help someone.

Rather than creating notransition class which was supposed to cancel the transition

.notransition {
  -webkit-transition: none !important;
  -moz-transition: none !important;
  -o-transition: none !important;
  transition: none !important;

I created moveTransition class

.moveTransition {
      -webkit-transition: left 3s, top 3s;
      -moz-transition: left 3s, top 3s;
      -o-transition: left 3s, top 3s;
      transition: left 3s, top 3s;

Then I added this class to element with js


And later in setTimeout, I removed it


I wasn't able to test it in different browsers but in chrome it works perfectly

CSS3 selector to find the 2nd div of the same class

What exactly is the structure of your HTML?

The previous CSS will work if the HTML is as such:




 <div class="foo"></div>
 <div class="foo">Find me</div>

But if you have the following HTML it will not work.

 <div class="other"></div>
 <div class="foo"></div>
 <div class="foo">Find me</div>

Simple put, there is no selector for the getting the index of the matches from the rest of the selector before it.

How to position a div scrollbar on the left hand side?

Working Example: JSFiddle


Cut and paste solution that works for all major browsers (Even Safari)

Any height or width will work

  .list_container {
    direction: rtl;
    height: 50px;
    width: 50px;

  .item_direction {
<div class="list_container">
  <div class="item_direction">1</div>
  <div class="item_direction">2</div>
  <div class="item_direction">3</div>
  <div class="item_direction">4</div>
  <div class="item_direction">5</div>
  <div class="item_direction">6</div>
  <div class="item_direction">7</div>
  <div class="item_direction">8</div>
  <div class="item_direction">9</div>
  <div class="item_direction">10</div>
  <div class="item_direction">11</div>
  <div class="item_direction">12</div>

Optionally add class="item_direction to each item to change the direction of the text flow back, while preserving the container direction.

Difference between clustered and nonclustered index

faster to read than non cluster as data is physically storted in index order we can create only one per table.(cluster index)

quicker for insert and update operation than a cluster index. we can create n number of non cluster index.

set initial viewcontroller in appdelegate - swift

Swift 5 & Xcode 11

So in xCode 11 the window solution is no longer valid inside of appDelegate. They moved this to the SceneDelgate. You can find this in the SceneDelgate.swift file.

You will notice it now has a var window: UIWindow? present.

In my situation I was using a TabBarController from a storyboard and wanted to set it as the rootViewController.

This is my code:


func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).

        self.window = self.window ?? UIWindow()//@JA- If this scene's self.window is nil then set a new UIWindow object to it.

        //@Grab the storyboard and ensure that the tab bar controller is reinstantiated with the details below.
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let tabBarController = storyboard.instantiateViewController(withIdentifier: "tabBarController") as! UITabBarController

        for child in tabBarController.viewControllers ?? [] {
            if let top = child as? StateControllerProtocol {
                print("State Controller Passed To:")
                top.setState(state: stateController)

        self.window!.rootViewController = tabBarController //Set the rootViewController to our modified version with the StateController instances

        print("Finished scene setting code")
        guard let _ = (scene as? UIWindowScene) else { return }

Make sure to add this to the correct scene method as I did here. Note that you will need to set the identifier name for the tabBarController or viewController you are using in the storyboard.

how to set the storyboard ID

In my case I was doing this to set a stateController to keep track of shared variables amongst the tab views. If you wish to do this same thing add the following code...


import Foundation

struct tdfvars{
    var rbe:Double = 1.4
    var t1half:Double = 1.5
    var alphaBetaLate:Double = 3.0
    var alphaBetaAcute:Double = 10.0
    var totalDose:Double = 6000.00
    var dosePerFraction:Double = 200.0
    var numOfFractions:Double = 30
    var totalTime:Double = 168
    var ldrDose:Double = 8500.0

//@JA - Protocol that view controllers should have that defines that it should have a function to setState
protocol StateControllerProtocol {
  func setState(state: StateController)

class StateController {
    var tdfvariables:tdfvars = tdfvars()

Note: Just use your own variables or whatever you are trying to keep track of instead, I just listed mine as an example in tdfvariables struct.

In each view of the TabController add the following member variable.

    class SettingsViewController: UIViewController {
    var stateController: StateController?
.... }

Then in those same files add the following:

extension SettingsViewController: StateControllerProtocol {
  func setState(state: StateController) {
    self.stateController = state

What this does is allows you to avoid the singleton approach to passing variables between the views. This allows easily for the dependency injection model which is much better long run then the singleton approach.

Implementing two interfaces in a class with same method. Which interface method is overridden?

This was marked as a duplicate to this question

You need Java 8 to get a multiple inheritance problem, but it is still not a diamon problem as such.

interface A {
    default void hi() { System.out.println("A"); }

interface B {
    default void hi() { System.out.println("B"); }

class AB implements A, B { // won't compile

new AB().hi(); // won't compile.

As JB Nizet comments you can fix this my overriding.

class AB implements A, B {
    public void hi() { A.super.hi(); }

However, you don't have a problem with

interface D extends A { }

interface E extends A { }

interface F extends A {
    default void hi() { System.out.println("F"); }

class DE implement D, E { }

new DE().hi(); // prints A

class DEF implement D, E, F { }

new DEF().hi(); // prints F as it is closer in the heirarchy than A.

CMake link to external library

arrowdodger's answer is correct and preferred on many occasions. I would simply like to add an alternative to his answer:

You could add an "imported" library target, instead of a link-directory. Something like:

# Your-external "mylib", add GLOBAL if the imported library is located in directories above the current.
add_library( mylib SHARED IMPORTED )
# You can define two import-locations: one for debug and one for release.
set_target_properties( mylib PROPERTIES IMPORTED_LOCATION ${CMAKE_BINARY_DIR}/res/ )

And then link as if this library was built by your project:


Such an approach would give you a little more flexibility: Take a look at the add_library( ) command and the many target-properties related to imported libraries.

I do not know if this will solve your problem with "updated versions of libs".

How do I crop an image in Java?

I'm giving this example because this actually work for my use case.

I was trying to use the AWS Rekognition API. The API returns a BoundingBox object:

BoundingBox boundingBox = faceDetail.getBoundingBox();

The code below uses it to crop the image:


private BufferedImage cropImage(BufferedImage image, BoundingBox box) {
        Rectangle goal = new Rectangle(Math.round(box.getLeft()* image.getWidth()),Math.round(box.getTop()* image.getHeight()),Math.round(box.getWidth() * image.getWidth()), Math.round(box.getHeight() * image.getHeight()));

        Rectangle clip = goal.intersection(new Rectangle(image.getWidth(), image.getHeight()));

        BufferedImage clippedImg = image.getSubimage(clip.x, clip.y , clip.width, clip.height);

        return clippedImg;

What's the pythonic way to use getters and setters?

You can use accessors/mutators (i.e. @attr.setter and @property) or not, but the most important thing is to be consistent!

If you're using @property to simply access an attribute, e.g.

class myClass:
    def __init__(a):
        self._a = a

    def a(self):
        return self._a

use it to access every* attribute! It would be a bad practice to access some attributes using @property and leave some other properties public (i.e. name without an underscore) without an accessor, e.g. do not do

class myClass:
    def __init__(a, b):
        self.a = a
        self.b = b

    def a(self):
        return self.a

Note that self.b does not have an explicit accessor here even though it's public.

Similarly with setters (or mutators), feel free to use @attribute.setter but be consistent! When you do e.g.

class myClass:
    def __init__(a, b):
        self.a = a
        self.b = b 

    def a(self, value):
        return self.a = value

It's hard for me to guess your intention. On one hand you're saying that both a and b are public (no leading underscore in their names) so I should theoretically be allowed to access/mutate (get/set) both. But then you specify an explicit mutator only for a, which tells me that maybe I should not be able to set b. Since you've provided an explicit mutator I am not sure if the lack of explicit accessor (@property) means I should not be able to access either of those variables or you were simply being frugal in using @property.

*The exception is when you explicitly want to make some variables accessible or mutable but not both or you want to perform some additional logic when accessing or mutating an attribute. This is when I am personally using @property and @attribute.setter (otherwise no explicit acessors/mutators for public attributes).

Lastly, PEP8 and Google Style Guide suggestions:

PEP8, Designing for Inheritance says:

For simple public data attributes, it is best to expose just the attribute name, without complicated accessor/mutator methods. Keep in mind that Python provides an easy path to future enhancement, should you find that a simple data attribute needs to grow functional behavior. In that case, use properties to hide functional implementation behind simple data attribute access syntax.

On the other hand, according to Google Style Guide Python Language Rules/Properties the recommendation is to:

Use properties in new code to access or set data where you would normally have used simple, lightweight accessor or setter methods. Properties should be created with the @property decorator.

The pros of this approach:

Readability is increased by eliminating explicit get and set method calls for simple attribute access. Allows calculations to be lazy. Considered the Pythonic way to maintain the interface of a class. In terms of performance, allowing properties bypasses needing trivial accessor methods when a direct variable access is reasonable. This also allows accessor methods to be added in the future without breaking the interface.

and cons:

Must inherit from object in Python 2. Can hide side-effects much like operator overloading. Can be confusing for subclasses.

Grep and Python

The natural question is why not just use grep?! But assuming you can't...

import re
import sys

file = open(sys.argv[2], "r")

for line in file:
     if[1], line):
         print line,

Things to note:

  • search instead of match to find anywhere in string
  • comma (,) after print removes carriage return (line will have one)
  • argv includes python file name, so variables need to start at 1

This doesn't handle multiple arguments (like grep does) or expand wildcards (like the Unix shell would). If you wanted this functionality you could get it using the following:

import re
import sys
import glob

for arg in sys.argv[2:]:
    for file in glob.iglob(arg):
        for line in open(file, 'r'):
            if[1], line):
                print line,

Show Current Location and Nearby Places and Route between two places using Google Maps API in Android

  1. First go through this tutorial for getting familiar with Android Google Maps and this for API 2.

  2. To retrive the current location of device see this answer or this another answer and for API 2

  3. Then you can get places near by your location using Google Place API and for use of Place Api see this blog.

  4. After getting Placemarks of near by location use this blog with source code to show markers on map with balloon overlay with API 2.

  5. You also have great sample to draw route between two points on map look here in these links Link1 and Link2 and this Great Answer.

After following these steps you will be easily able to do your application. The only condition is, you will have to read it and understand it, because like magic its not going to be complete in a click.

Java, looping through result set

Result Set are actually contains multiple rows of data, and use a cursor to point out current position. So in your case, rs4.getString(1) only get you the data in first column of first row. In order to change to next row, you need to call next()

a quick example

while ( {
    String sid = rs.getString(1);
    String lid = rs.getString(2);
    // Do whatever you want to do with these 2 values

there are many useful method in ResultSet, you should take a look :)

Converting a Date object to a calendar object

Here's your method:

public static Calendar toCalendar(Date date){ 
  Calendar cal = Calendar.getInstance();
  return cal;

Everything else you are doing is both wrong and unnecessary.

BTW, Java Naming conventions suggest that method names start with a lower case letter, so it should be: dateToCalendar or toCalendar (as shown).

OK, let's milk your code, shall we?

DateFormat formatter = new SimpleDateFormat("yyyyMMdd");
date = (Date)formatter.parse(date.toString()); 

DateFormat is used to convert Strings to Dates (parse()) or Dates to Strings (format()). You are using it to parse the String representation of a Date back to a Date. This can't be right, can it?

How to edit a text file in my terminal

If you are still inside the vi editor, you might be in a different mode from the one you want. Hit ESC a couple of times (until it rings or flashes) and then "i" to enter INSERT mode or "a" to enter APPEND mode (they are the same, just start before or after current character).

If you are back at the command prompt, make sure you can locate the file, then navigate to that directory and perform the mentioned "vi helloWorld.txt". Once you are in the editor, you'll need to check the vi reference to know how to perform the editions you want (you may want to google "vi reference" or "vi cheat sheet").

Once the edition is done, hit ESC again, then type :wq to save your work or :q! to quit without saving.

For quick reference, here you have a text-based cheat sheet.

Why can't I use background image and color together?

And to add to this answer, make sure the image itself has a transparent background.

How to find integer array size in java

we can find length of array by using array_name.length attribute

int [] i = i.length;

Golang read request body

Inspecting and mocking request body

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

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

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

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

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

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

Inspecting / modifying response body

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

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

type MyResponseWriter struct {
    buf *bytes.Buffer

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

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

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

Full example

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

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

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

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

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

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

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

Centering elements in jQuery Mobile

Adjust as your requirement

      margin:0.5em 10px;

(HTML) Download a PDF file instead of opening them in browser when clicked

This is only possible with setting a http response header by the server side code. Namely;

Content-Disposition: attachment; filename=fname.ext

Qt: How do I handle the event of the user pressing the 'X' (close) button?

If you have a QMainWindow you can override closeEvent method.

#include <QCloseEvent>
void MainWindow::closeEvent (QCloseEvent *event)
    QMessageBox::StandardButton resBtn = QMessageBox::question( this, APP_NAME,
                                                                tr("Are you sure?\n"),
                                                                QMessageBox::Cancel | QMessageBox::No | QMessageBox::Yes,
    if (resBtn != QMessageBox::Yes) {
    } else {

If you're subclassing a QDialog, the closeEvent will not be called and so you have to override reject():

void MyDialog::reject()
    QMessageBox::StandardButton resBtn = QMessageBox::Yes;
    if (changes) {
        resBtn = QMessageBox::question( this, APP_NAME,
                                        tr("Are you sure?\n"),
                                        QMessageBox::Cancel | QMessageBox::No | QMessageBox::Yes,
    if (resBtn == QMessageBox::Yes) {

How to find length of a string array?

String car [];

is a reference to an array of String-s. You can't see a length because there is no array there!

Best way to detect Mac OS X or Windows computers with JavaScript or jQuery

Let me know if this works. Way to detect an Apple device (Mac computers, iPhones, etc.) with help from
What is the list of possible values for navigator.platform as of today?

var deviceDetect = navigator.platform;
var appleDevicesArr = ['MacIntel', 'MacPPC', 'Mac68K', 'Macintosh', 'iPhone', 
'iPod', 'iPad', 'iPhone Simulator', 'iPod Simulator', 'iPad Simulator', 'Pike 
v7.6 release 92', 'Pike v7.8 release 517'];

// If on Apple device
if(appleDevicesArr.includes(deviceDetect)) {
    // Execute code
// If NOT on Apple device
else {
    // Execute code

How can I render Partial views in mvc 3?

Create your partial view something like:

@model YourModelType
  <!-- HTML to render your object -->

Then in your view use:

@Html.Partial("YourPartialViewName", Model)

If you do not want a strongly typed partial view remove the @model YourModelType from the top of the partial view and it will default to a dynamic type.


The default view engine will search for partial views in the same folder as the view calling the partial and then in the ~/Views/Shared folder. If your partial is located in a different folder then you need to use the full path. Note the use of ~/ in the path below.

@Html.Partial("~/Views/Partials/SeachResult.cshtml", Model)

How can I view an old version of a file with Git?

You can use a script like this to dump all the versions of a file to separate files:

e.g. path/to/somefile.txt

Get the script here as an answer to another similar question

How to create an array of 20 random bytes?

Java 7 introduced ThreadLocalRandom which is isolated to the current thread.

This is an another rendition of maerics's solution.

final byte[] bytes = new byte[20];

Modify request parameter with servlet filter

You can use Regular Expression for Sanitization. Inside filter before calling chain.doFilter(request, response) method, call this code. Here is Sample Code:

for (Enumeration en = request.getParameterNames(); en.hasMoreElements(); ) {
String name = (String)en.nextElement();
String values[] = request.getParameterValues(name);
int n = values.length;
    for(int i=0; i < n; i++) {
     values[i] = values[i].replaceAll("[^\\dA-Za-z ]","").replaceAll("\\s+","+").trim();   

How to get Locale from its String representation in Java?

See the Locale.getLanguage(), Locale.getCountry()... Store this combination in the database instead of the "programatic name"...
When you want to build the Locale back, use public Locale(String language, String country)

Here is a sample code :)

// May contain simple syntax error, I don't have java right now to test..
// but this is a bigger picture for your algo...
public String localeToString(Locale l) {
    return l.getLanguage() + "," + l.getCountry();

public Locale stringToLocale(String s) {
    StringTokenizer tempStringTokenizer = new StringTokenizer(s,",");
    String l = tempStringTokenizer.nextElement();
    String c = tempStringTokenizer.nextElement();
    return new Locale(l,c);

How do I debug Windows services in Visual Studio?

Use the following code in service OnStart method:


Choose the Visual Studio option from the pop up message.

Note: To use it in only Debug mode, a #if DEBUG compiler directive can be used, as follows. This will prevent accidental or debugging in release mode on a production server.


Swift Bridging Header import issue

After initial few days of struggle, I finally managed to successfully integrate Facebook signup to my iOS app. Here are the steps(I am assuming you have already installed Facebook SDK v4.1 or above in your machines):

  1. Add the Facebook frameworks - FBSDKCoreKit,FBSDKLoginKit under your project.
  2. Make no changes in the Build settings as FB SDK v4.1 and above doesn't need anymore bridging header files.
  3. Import the FBSDKCorekit, FBSDKLoginKit in ViewController.swift, AppDelegate.swift files
  4. Add informations in the pList as mentioned here

  5. Build your app. And wohoo! no compile time errors.

What are the benefits of using C# vs F# or F# vs C#?

F# is not yet-another-programming-language if you are comparing it to C#, C++, VB. C#, C, VB are all imperative or procedural programming languages. F# is a functional programming language.

Two main benefits of functional programming languages (compared to imperative languages) are 1. that they don't have side-effects. This makes mathematical reasoning about properties of your program a lot easier. 2. that functions are first class citizens. You can pass functions as parameters to another functions just as easily as you can other values.

Both imperative and functional programming languages have their uses. Although I have not done any serious work in F# yet, we are currently implementing a scheduling component in one of our products based on C# and are going to do an experiment by coding the same scheduler in F# as well to see if the correctness of the implementation can be validated more easily than with the C# equivalent.

Determining 32 vs 64 bit in C++

I'd place 32-bit and 64-bit sources in different files and then select appropriate source files using the build system.

mkdir's "-p" option

-p|--parent will be used if you are trying to create a directory with top-down approach. That will create the parent directory then child and so on iff none exists.

-p, --parents no error if existing, make parent directories as needed

About rlidwka it means giving full or administrative access. Found it here

Convert txt to csv python script

You need to split the line first.

import csv

with open('log.txt', 'r') as in_file:
    stripped = (line.strip() for line in in_file)
    lines = (line.split(",") for line in stripped if line)
    with open('log.csv', 'w') as out_file:
        writer = csv.writer(out_file)
        writer.writerow(('title', 'intro'))

Forward declaration of a typedef in C++

To "fwd declare a typedef" you need to fwd declare a class or a struct and then you can typedef declared type. Multiple identical typedefs are acceptable by compiler.

long form:

class MyClass;
typedef MyClass myclass_t;

short form:

typedef class MyClass myclass_t;

get data from mysql database to use in javascript

Do you really need to "build" it from javascript or can you simply return the built HTML from PHP and insert it into the DOM?

  1. Send AJAX request to php script
  2. PHP script processes request and builds table
  3. PHP script sends response back to JS in form of encoded HTML
  4. JS takes response and inserts it into the DOM

Installing NumPy via Anaconda in Windows

The above answers seem to resolve the issue. If it doesn't, then you may also try to update conda using the following command.

conda update conda

And then try to install numpy using

conda install numpy

How to stop console from closing on exit?

You can simply press Ctrl+F5 instead of F5 to run the built code. Then it will prompt you to press any key to continue. Or you can use this line -> system("pause"); at the end of the code to make it wait until you press any key.

However, if you use the above line, system("pause"); and press Ctrl+F5 to run, it will prompt you twice!

How can I ping a server port with PHP?

Try this :

echo exec('ping -n 1 -w 1');

Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/JDBC_DBO]]

I had the same problem.

org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]

Already all robotet. My pom.xml:"> 4.0.0 com.springapp war 1.0-SNAPSHOT war rent</name>-->






    <!--Spring Security-->



How to get current instance name from T-SQL

To get the list of server and instance that you're connected to:

select * from Sys.Servers

To get the list of databases that connected server has:

SELECT * from sys.databases;

IF - ELSE IF - ELSE Structure in Excel

=IF(CR<=10, "RED", if(CR<50, "YELLOW", if(CR<101, "GREEN")))

CR = ColRow (Cell) This is an example. In this example when value in Cell is less then or equal to 10 then RED word will appear on that cell. In the same manner other if conditions are true if first if is false.

Custom Card Shape Flutter SDK

You can also customize the card theme globally with ThemeData.cardTheme:

  title: 'savvy',
  theme: ThemeData(
    cardTheme: CardTheme(
      shape: RoundedRectangleBorder(
        borderRadius: const BorderRadius.all(
    // ...

Python CSV error: line contains NULL byte

Converting the encoding of the source file from UTF-16 to UTF-8 solve my problem.

How to convert a file to utf-8 in Python?

import codecs
BLOCKSIZE = 1048576 # or some other, desired size in bytes
with, "r", "utf-16") as sourceFile:
    with, "w", "utf-8") as targetFile:
        while True:
            contents =
            if not contents:

Android: upgrading DB version and adding new table

Your code looks correct. My suggestion is that the database already thinks it's upgraded. If you executed the project after incrementing the version number, but before adding the execSQL call, the database on your test device/emulator may already believe it's at version 2.

A quick way to verify this would be to change the version number to 3 -- if it upgrades after that, you know it was just because your device believed it was already upgraded.

error: package javax.servlet does not exist

The answer provided by @Matthias Herlitzius is mostly correct. Just for further clarity.

The servlet-api jar is best left up to the server to manage see here for detail

With that said, the dependency to add may vary according to your server/container. For example in Wildfly the dependency would be


So becareful to check how your container has provided the servlet implementation.

Google Maps API warning: NoApiKeys

Creating and using the key is the way to go. The usage is free until your application reaches 25.000 calls per day on 90 consecutive days.

BTW.: In the google Developer documentation it says you shall add the api key as option {key:yourKey} when calling the API to create new instances. This however doesn't shush the console warning. You have to add the key as a parameter when including the api.

<script src=""></script>

Get the key here: GoogleApiKey Generation site

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

The error usually gets introduced while creation of CSV. Try using Linux for saving the CSV as a TextCSV. Libre Office in Ubuntu can enforce the encoding to be UTF-8, worked for me. I wasted a lot of time trying this on Mac OS. Linux is the key. I've tested on Ubuntu.

Good Luck

Viewing localhost website from mobile device

In additional you should disable your antivirus or manage it to open 80 port on your system.

IntelliJ does not show project folders

OS:Mac && IDE: IntelliJ && Project: Maven build

  1. Navigate to File>Project Structure>Modules.
  2. In right-hand area; list of modules would be present.
  3. Delete the default one selected and close IntelliJ.
  4. Next Open again; IntelliJ will ask if you want to treat the project as Maven project.
  5. Accept that popup and you are good to go.

How do I make a placeholder for a 'select' box?

Here is a CSS solution that works beautifully. The content is added (and absolutely positioned relative to the container) after the containing element (via :after pseudo-class).

It gets its text from the placeholder attribute that I defined where I used the directive (attr(placeholder)). Another key factor is pointer-events: none - this allows clicks on the placeholder text to pass through to the select. Otherwise it won't drop down if the user clicks the text.

I add the .empty class myself in my select directive, but normally I find that angular adds/removes .ng-empty for me (I assume it's because I'm injecting version 1.2 of Angular in my code sample).

(The sample also demonstrates how to wrap HTML elements in AngularJS to create your own custom inputs)

var app = angular.module("soDemo", []);_x000D_
app.controller("soDemoController", function($scope) {_x000D_
  var vm = {};_x000D_
  vm.names = [{_x000D_
      id: 1,_x000D_
      name: 'Jon'_x000D_
      id: 2,_x000D_
      name: 'Joe'_x000D_
    }, {_x000D_
      id: 3,_x000D_
      name: 'Bob'_x000D_
    }, {_x000D_
      id: 4,_x000D_
      name: 'Jane'_x000D_
  $scope.vm = vm;_x000D_
app.directive('soSelect', function soSelect() {_x000D_
  var directive = {_x000D_
    restrict: 'E',_x000D_
    require: 'ngModel',_x000D_
    scope: {_x000D_
      'valueProperty': '@',_x000D_
      'displayProperty': '@',_x000D_
      'modelProperty': '=',_x000D_
      'source': '=',_x000D_
    link: link,_x000D_
    template: getTemplate_x000D_
  return directive;_x000D_
  function link(scope, element, attrs, ngModelController) {_x000D_
    ///////////// IMPLEMENTATION_x000D_
    function init() {_x000D_
    function initDataBinding() {_x000D_
      ngModelController.$render = function() {_x000D_
        if (scope.model === ngModelController.$viewValue) return;_x000D_
        scope.model = ngModelController.$viewValue;_x000D_
      scope.$watch('model', function(newValue) {_x000D_
        if (newValue === undefined) {_x000D_
  function getTemplate(element, attrs) {_x000D_
    var attributes = [_x000D_
    if (angular.isDefined(attrs.placeholder)) {_x000D_
    var ngOptions = '';_x000D_
    if (angular.isDefined(attrs.valueProperty)) {_x000D_
      ngOptions += 'item.' + attrs.valueProperty + ' as ';_x000D_
    ngOptions += 'item.' + attrs.displayProperty + ' for item in source';_x000D_
    ngOptions += '"';_x000D_
    attributes.push('ng-options="' + ngOptions + '"');_x000D_
    var html = '<select ' + attributes.join(' ') + '></select>';_x000D_
    return html;_x000D_
so-select {_x000D_
  position: relative;_x000D_
so-select select {_x000D_
  font-family: 'Helvetica';_x000D_
  display: inline-block;_x000D_
  height: 24px;_x000D_
  width: 200px;_x000D_
  padding: 0 1px;_x000D_
  font-size: 12px;_x000D_
  color: #222;_x000D_
  border: 1px solid #c7c7c7;_x000D_
  border-radius: 4px;_x000D_
so-select.empty:before {_x000D_
  font-family: 'Helvetica';_x000D_
  font-size: 12px;_x000D_
  content: attr(placeholder);_x000D_
  position: absolute;_x000D_
  pointer-events: none;_x000D_
  left: 6px;_x000D_
  top: 3px;_x000D_
  z-index: 0;_x000D_
  color: #888;_x000D_
<script src=""></script>_x000D_
<div ng-app="soDemo" ng-controller="soDemoController">_x000D_
  <so-select value-property="id" display-property="name" source="vm.names" ng-model="vm.nameId" placeholder="(select name)"></so-select>_x000D_

Generate .pem file used to set up Apple Push Notifications

To enable Push Notification for your iOS app, you will need to create and upload the Apple Push Notification Certificate (.pem file) to us so we will be able to connect to Apple Push Server on your behalf.

(Updated version with updated screen shots Here)

Step 1: Login to iOS Provisioning Portal, click "Certificates" on the left navigation bar. Then, click "+" button.

enter image description here

Step 2: Select Apple Push Notification service SSL (Production) option under Distribution section, then click "Continue" button.

enter image description here

Step 3: Select the App ID you want to use for your BYO app (How to Create An App ID), then click "Continue" to go to next step.

enter image description here

Step 4: Follow the steps "About Creating a Certificate Signing Request (CSR)" to create a Certificate Signing Request.

enter image description here

To supplement the instruction provided by Apple. Here are some of the additional screenshots to assist you to complete the required steps:

Step 4 Supplementary Screenshot 1: Navigate to Certificate Assistant of Keychain Access on your Mac.

enter image description here

Step 4 Supplementary Screenshot 2: Fill in the Certificate Information. Click Continue.

enter image description here

Step 5: Upload the ".certSigningRequest" file which is generated in Step 4, then click "Generate" button.

enter image description here

Step 6: Click "Done" to finish the registration, the iOS Provisioning Portal Page will be refreshed that looks like the following screen:

enter image description here

Then Click "Download" button to download the certificate (.cer file) you've created just now. - Double click the downloaded file to install the certificate into Keychain Access on your Mac.

Step 7: On your Mac, go to "Keychain", look for the certificate you have just installed. If unsure which certificate is the correct one, it should start with "Apple Production IOS Push Services:" followed by your app's bundle ID.

enter image description here

Step 8: Expand the certificate, you should see the private key with either your name or your company name. Select both items by using the "Select" key on your keyboard, right click (or cmd-click if you use a single button mouse), choose "Export 2 items", like Below:

enter image description here

Then save the p12 file with name "pushcert.p12" to your Desktop - now you will be prompted to enter a password to protect it, you can either click Enter to skip the password or enter a password you desire.

Step 9: Now the most difficult part - open "Terminal" on your Mac, and run the following commands:

cd Desktop
openssl pkcs12 -in pushcert.p12 -out pushcert.pem -nodes -clcerts

Step 10: Remove pushcert.p12 from Desktop to avoid mis-uploading it to Build Your Own area. Open "Terminal" on your Mac, and run the following commands:

cd Desktop
rm pushcert.p12

Step 11 - NEW AWS UPDATE: Create new pushcert.p12 to submit to AWS SNS. Double click on the new pushcert.pem, then export the one highlighed on the green only.

enter image description here Credit: AWS new update

Now you have successfully created an Apple Push Notification Certificate (.p12 file)! You will need to upload this file to our Build Your Own area later on. :)

How do I use hexadecimal color strings in Flutter?

As the Color constructor does not support hexadecimal string, so we should find other alternatives.

There are several possibilities :

1- The first one is to create a small function that will allow you to convert a color hex-string to a Color object.

Code :

   Color colorFromHex(String hexColor) {
   final hexCode = hexColor.replaceAll('#', '');
   if (hexColor.length == 6) {
    hexColor = 'FF' + hexColor; // FF as the opacity value if you don't add it.
  return Color(int.parse('FF$hexCode', radix: 16));

Usage :

          color: colorFromHex('abcdff'),
          child: Text(
            'Never stop learning',
            style: TextStyle(color: colorFromHex('bbffffcc')),

2- The second possibility is to use the supercharged package. Supercharged brings all the comfort features from languages like Kotlin to all Flutter developers.

Add the dependency supercharged: ^1.X.X (find recent version) to your project and start using Supercharged everywhere:

import 'package:supercharged/supercharged.dart';

Now ,transform any String to colors

Code :

"#ff00ff".toColor(); // painless hex to color
"red".toColor(); // supports all web color names

You can also use the hexcolor package which is also great .

Change background of LinearLayout in Android

If your using a background resource and wish to change the resource out you can use setBackgroundResource() function.


A background resource in XML would look like:


What does %s mean in a python format string?

Here is a good example in Python3.

  >>> a = input("What is your name?")
  What is your name?Peter

  >>> b = input("Where are you from?")
  Where are you from?DE

  >>> print("So you are %s of %s" % (a, b))
  So you are Peter of DE

How do I customize Facebook's sharer.php

Sharer.php no longer allows you to customize. The page you share will be scraped for OG Tags and that data will be shared.

To properly customize, use FB.UI which comes with the JS-SDK.

DATEDIFF function in Oracle

Just subtract the two dates:

select date '2000-01-02' - date '2000-01-01' as dateDiff
from dual;

The result will be the difference in days.

More details are in the manual:

Is ncurses available for windows?

Such a thing probably does not exist "as-is". It doesn't really exist on Linux or other UNIX-like operating systems either though.

ncurses is only a library that helps you manage interactions with the underlying terminal environment. But it doesn't provide a terminal emulator itself.

The thing that actually displays stuff on the screen (which in your requirement is listed as "native resizable win32 windows") is usually called a Terminal Emulator. If you don't like the one that comes with Windows (you aren't alone; no person on Earth does) there are a few alternatives. There is Console, which in my experience works sometimes and appears to just wrap an underlying Windows terminal emulator (I don't know for sure, but I'm guessing, since there is a menu option to actually get access to that underlying terminal emulator, and sure enough an old crusty Windows/DOS box appears which mirrors everything in the Console window).

A better option

Another option, which may be more appealing is puttycyg. It hooks in to Putty (which, coming from a Linux background, is pretty close to what I'm used to, and free) but actually accesses an underlying cygwin instead of the Windows command interpreter (CMD.EXE). So you get all the benefits of Putty's awesome terminal emulator, as well as nice ncurses (and many other) libraries provided by cygwin. Add a couple command line arguments to the Shortcut that launches Putty (or the Batch file) and your app can be automatically launched without going through Putty's UI.

LINQ query to return a Dictionary<string, string>

Look at the ToLookup and/or ToDictionary extension methods.

VB.NET Connection string (Web.Config, App.Config)

Public Function connectDB() As OleDbConnection

        Dim Con As New OleDbConnection
        'Con.ConnectionString = "Provider=SQLOLEDB.1;Persist Security Info=False;User ID=sa;Initial Catalog=" & DBNAME & ";Data Source=" & DBSERVER & ";Pwd=" & DBPWD & ""
        Con.ConnectionString = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=DBNAME;Data Source=DBSERVER-TOSH;User ID=Sa;Pwd= & DBPWD"
        Catch ex As Exception
        End Try
        Return Con
    End Function

Setting the selected value on a Django forms.ChoiceField

Both Tom and Burton's answers work for me eventually, but I had a little trouble figuring out how to apply them to a ModelChoiceField.

The only trick to it is that the choices are stored as tuples of (<model's ID>, <model's unicode repr>), so if you want to set the initial model selection, you pass the model's ID as the initial value, not the object itself or it's name or anything else. Then it's as simple as:

form = EmployeeForm(initial={'manager': manager_employee_id})

Alternatively the initial argument can be ignored in place of an extra line with:

form.fields['manager'].initial = manager_employee_id


Maybe try this

Select cust.*

From dbo.Customers cust
Left Join dbo.Subscribers subs on cust.Customer_ID = subs.Customer_ID
Where subs.Customer_Id Is Null

Why is vertical-align: middle not working on my span or div?

Here is the latest simplest solution - no need to change anything, just add three lines of CSS rules to your container of the div where you wish to center at. I love Flex Box #LoveFlexBox

.main {_x000D_
  /* I changed height to 200px to make it easy to see the alignment. */_x000D_
  height: 200px;_x000D_
  vertical-align: middle;_x000D_
  border: 1px solid #000000;_x000D_
  padding: 2px;_x000D_
  /* Just add the following three rules to the container of which you want to center at. */_x000D_
  display: flex;_x000D_
  flex-direction: column;_x000D_
  justify-content: center;_x000D_
  /* This is true vertical center, no math needed. */_x000D_
.inner {_x000D_
  border: 1px solid #000000;_x000D_
.second {_x000D_
  border: 1px solid #000000;_x000D_
<div class="main">_x000D_
  <div class="inner">This box should be centered in the larger box_x000D_
    <div class="second">Another box in here</div>_x000D_
  <div class="inner">This box should be centered in the larger box_x000D_
    <div class="second">Another box in here</div>_x000D_


the justify-content value can be set to the following few options:

  • flex-start, which will align the child div to where the flex flow starts in its parent container. In this case, it will stay on top.

  • center, which will align the child div to the center of its parent container. This is really neat, because you don't need to add an additional div to wrap around all children to put the wrapper in a parent container to center the children. Because of that, this is the true vertical center (in the column flex-direction. similarly, if you change the flow-direction to row, it will become horizontally centered.

  • flex-end, which will align the child div to where the flex flow ends in its parent container. In this case, it will move to bottom.

  • space-between, which will spread all children from the beginning of the flow to the end of the flow. If the demo, I added another child div, to show they are spread out.

  • space-around, similar to space-between, but with half of the space in the beginning and end of the flow.

Receive result from DialogFragment

As you can see here there is a very simple way to do that.

In your DialogFragment add an interface listener like:

public interface EditNameDialogListener {
    void onFinishEditDialog(String inputText);

Then, add a reference to that listener:

private EditNameDialogListener listener;

This will be used to "activate" the listener method(s), and also to check if the parent Activity/Fragment implements this interface (see below).

In the Activity/FragmentActivity/Fragment that "called" the DialogFragment simply implement this interface.

In your DialogFragment all you need to add at the point where you'd like to dismiss the DialogFragment and return the result is this:


Where mEditText.getText().toString() is what will be passed back to the calling Activity.

Note that if you want to return something else simply change the arguments the listener takes.

Finally, you should check whether the interface was actually implemented by the parent activity/fragment:

public void onAttach(Context context) {
    // Verify that the host activity implements the callback interface
    try {
        // Instantiate the EditNameDialogListener so we can send events to the host
        listener = (EditNameDialogListener) context;
    } catch (ClassCastException e) {
        // The activity doesn't implement the interface, throw exception
        throw new ClassCastException(context.toString()
                + " must implement EditNameDialogListener");

This technique is very flexible and allow calling back with the result even if your don;t want to dismiss the dialog just yet.

Easiest way to flip a boolean value?

Just for information - if instead of an integer your required field is a single bit within a larger type, use the 'xor' operator instead:

int flags;

int flag_a = 0x01;
int flag_b = 0x02;
int flag_c = 0x04;

/* I want to flip 'flag_b' without touching 'flag_a' or 'flag_c' */
flags ^= flag_b;

/* I want to set 'flag_b' */
flags |= flag_b;

/* I want to clear (or 'reset') 'flag_b' */
flags &= ~flag_b;

/* I want to test 'flag_b' */
bool b_is_set = (flags & flag_b) != 0;

Converting from Integer, to BigInteger

The method you want is BigInteger#valueOf(long val).


BigInteger bi = BigInteger.valueOf(myInteger.intValue());

Making a String first is unnecessary and undesired.

Detect backspace and del on "input" event?

It's an old question, but if you wanted to catch a backspace event on input, and not keydown, keypress, or keyup—as I've noticed any one of these break certain functions I've written and cause awkward delays with automated text formatting—you can catch a backspace using inputType:

document.getElementsByTagName('input')[0].addEventListener('input', function(e) {
    if (e.inputType == "deleteContentBackward") {
        // your code here

JSON response parsing in Javascript to get key/value pair

Ok, here is the JS code:

var data = JSON.parse('{"c":{"a":{"name":"cable - black","value":2}}}')

for (var event in data) {
    var dataCopy = data[event];
    for (data in dataCopy) {
        var mainData = dataCopy[data];
        for (key in mainData) {
            if (key.match(/name|value/)) {
                alert('key : ' + key + ':: value : ' + mainData[key])


Get last 3 characters of string

The easiest way would be using Substring

string str = "AM0122200204";
string substr = str.Substring(str.Length - 3);

Using the overload with one int as I put would get the substring of a string, starting from the index int. In your case being str.Length - 3, since you want to get the last three chars.

How to use the priority queue STL for objects?

You would write a comparator class, for example:

struct CompareAge {
    bool operator()(Person const & p1, Person const & p2) {
        // return "true" if "p1" is ordered before "p2", for example:
        return p1.age < p2.age;

and use that as the comparator argument:

priority_queue<Person, vector<Person>, CompareAge>

Using greater gives the opposite ordering to the default less, meaning that the queue will give you the lowest value rather than the highest.

Error converting data types when importing from Excel to SQL Server 2008

A workaround to consider in a pinch:

  1. save a copy of the excel file, modify the column to format type 'text'
  2. copy the column values and paste to a text editor, save the file (call it tmp.txt).
  3. modify the data in the text file to start and end with a character so that the SQL Server import mechanism will recognize as text. If you have a fancy editor, use included tools. I use awk in cygwin on my windows laptop. For example, I start end end the column value with a single quote, like "$ awk '{print "\x27"$1"\x27"}' ./tmp.txt > ./tmp2.txt"
  4. copy and paste the data from tmp2.txt over top of the necessary column in the excel file, and save the excel file
  5. run the sql server import for your modified excel file... be sure to double check the data type chosen by the importer is not numeric... if it is, repeat the above steps with a different set of characters

The data in the database will have the quotes once the import is done... you can update the data later on to remove the quotes, or use the "replace" function in your read query, such as "replace([dbo].[MyTable].[MyColumn], '''', '')"

How to randomize (or permute) a dataframe rowwise and columnwise?

Take a look at permatswap() in the vegan package. Here is an example maintaining both row and column totals, but you can relax that and fix only one of the row or column sums.

mat <- matrix(c(1,1,0,0,0,0,0,1,1,0,0,0,1,1,1,0,1,0,1,1), ncol = 5)
out <- permatswap(mat, times = 99, burnin = 20000, thin = 500, mtype = "prab")

This gives:

R> out$perm[[1]]
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    0    1    1    1
[2,]    0    1    0    1    0
[3,]    0    0    0    1    1
[4,]    1    0    0    0    1
R> out$perm[[2]]
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    1    0    1    1
[2,]    0    0    0    1    1
[3,]    1    0    0    1    0
[4,]    0    0    1    0    1

To explain the call:

out <- permatswap(mat, times = 99, burnin = 20000, thin = 500, mtype = "prab")
  1. times is the number of randomised matrices you want, here 99
  2. burnin is the number of swaps made before we start taking random samples. This allows the matrix from which we sample to be quite random before we start taking each of our randomised matrices
  3. thin says only take a random draw every thin swaps
  4. mtype = "prab" says treat the matrix as presence/absence, i.e. binary 0/1 data.

A couple of things to note, this doesn't guarantee that any column or row has been randomised, but if burnin is long enough there should be a good chance of that having happened. Also, you could draw more random matrices than you need and discard ones that don't match all your requirements.

Your requirement to have different numbers of changes per row, also isn't covered here. Again you could sample more matrices than you want and then discard the ones that don't meet this requirement also.

How to uninstall Golang?

sudo apt-get remove golang-go
sudo apt-get remove --auto-remove golang-go

This is perfect for Ubuntu 18.18

VB.Net: Dynamically Select Image from My.Resources

This works for me at runtime too:

UltraPictureBox1.Image = My.Resources.MyPicture

No strings involved and if I change the name it is automatically updated by refactoring.

How to output numbers with leading zeros in JavaScript?

function zfill(num, len) {return (Array(len).join("0") + num).slice(-len);}

pyplot scatter plot marker size

If the size of the circles corresponds to the square of the parameter in s=parameter, then assign a square root to each element you append to your size array, like this: s=[1, 1.414, 1.73, 2.0, 2.24] such that when it takes these values and returns them, their relative size increase will be the square root of the squared progression, which returns a linear progression.

If I were to square each one as it gets output to the plot: output=[1, 2, 3, 4, 5]. Try list interpretation: s=[numpy.sqrt(i) for i in s]

How can I view the Git history in Visual Studio Code?

I recommend you this repository,

Git History Git History

It does exactly what you need and has these features:

  • View the details of a commit, such as author name, email, date, committer name, email, date and comments.
  • View a previous copy of the file or compare it against the local workspace version or a previous version.
  • View the changes to the active line in the editor (Git Blame).
  • Configure the information displayed in the list
  • Use keyboard shortcuts to view history of a file or line
  • View the Git log (along with details of a commit, such as author name, email, comments and file changes).

How to select where ID in Array Rails ActiveRecord without exception

You can also use it in named_scope if You want to put there others conditions

for example include some other model:

named_scope 'get_by_ids', lambda { |ids| { :include => [:comments], :conditions => [" IN (?)", ids] } }

How to get Django and ReactJS to work together?

Hoping to provide a more nuanced answer than any of the ones here, especially as some things have changed since this was originally asked ~4 years ago, and because many of the top-voted answers claiming that you have to set this up as two separate applications are not accurate.

You have two primary architecture options:

  1. A completely decoupled client/server approach using something like create-react-app and Django REST Framework
  2. A hybrid architecture where you set up a React build pipeline (likely using webpack) and then include the compiled files as static files in your Django templates.

These might look something like this:

Option 1 (Client/Server Architecture):

Client / Server Architecture

Option 2 (Hybrid Architecture):

Hybrid Architecture

The decision between these two will depend on your / your team's experience, as well as the complexity of your UI. The first option is good if you have a lot of JS experience, want to keep your front-end / back-end developers separate, or want to write your entire application as a React single-page-app. The second option is generally better if you are more familiar with Django and want to move quickly while also using React for some parts of your app. I find it's a particularly good fit for full-stack solo-developers.

There is a lot more information in the series "Modern JavaScript for Django Developers", including choosing your architecture, integrating your JS build into a Django project and building a single-page React app.

Full disclosure, I'm the author of that series.

Difference between View and ViewGroup in Android


  1. View objects are the basic building blocks of User Interface(UI) elements in Android.
  2. View is a simple rectangle box which responds to the user's actions.
  3. Examples are EditText, Button, CheckBox etc..
  4. View refers to the android.view.View class, which is the base class of all UI classes.


  1. ViewGroup is the invisible container. It holds View and ViewGroup
  2. For example, LinearLayout is the ViewGroup that contains Button(View), and other Layouts also.
  3. ViewGroup is the base class for Layouts.

How to use sed to replace only the first occurrence in a file?

This might work for you (GNU sed):

sed -si '/#include/{s//& "newfile.h\n&/;:a;$!{n;ba}}' file1 file2 file....

or if memory is not a problem:

sed -si ':a;$!{N;ba};s/#include/& "newfile.h\n&/' file1 file2 file...

Why is exception.printStackTrace() considered bad practice?

First thing printStackTrace() is not expensive as you state, because the stack trace is filled when the exception is created itself.

The idea is to pass anything that goes to logs through a logger framework, so that the logging can be controlled. Hence instead of using printStackTrace, just use something like Logger.log(msg, exception);

WPF popup window


<Popup Name="myPopup">
      <TextBlock Name="myPopupText" 
        Popup Text


    Popup codePopup = new Popup();
    TextBlock popupText = new TextBlock();
    popupText.Text = "Popup Text";
    popupText.Background = Brushes.LightBlue;
    popupText.Foreground = Brushes.Blue;
    codePopup.Child = popupText;

you can find more details about the Popup Control from MSDN documentation.

MSDN documentation on Popup control

Use <Image> with a local file

To display image from local folder, you need to write down code:

 <Image source={require('../assets/self.png')}/>

Here I have put my image in asset folder.

Copy files to network computers on windows command line

check Robocopy:

ROBOCOPY \\server-source\c$\VMExports\ C:\VMExports\ /E /COPY:DAT

make sure you check what robocopy parameter you want. this is just an example. type robocopy /? in a comandline/powershell on your windows system.

Get index of selected option with jQuery

The first methods seem to work in the browsers that I tested, but the option tags doesn't really correspond to actual elements in all browsers, so the result may vary.

Just use the selectedIndex property of the DOM element:



Since version 1.6 jQuery has the prop method that can be used to read properties:


Presto SQL - Converting a date string to date format

date_format requires first argument as timestamp so not the best way to convert a string. Use date_parse instead.

Also, use %c for non zero-padded month, %e for non zero-padded day of the month and %Y for four digit year.

SELECT date_parse('7/22/2016 6:05:04 PM', '%c/%e/%Y %r')

Vuex - Computed property "name" was assigned to but it has no setter

I was facing exact same error

Computed property "callRingtatus" was assigned to but it has no setter

here is a sample code according to my scenario

computed: {

            return this.$store.getters['chat/callState']===2


I change the above code into the following way

computed: {

       return this.$

fetch values from vuex store state instead of getters inside the computed hook

How to push to History in React Router v4?

Now with react-router v5 you can use the useHistory hook like this:

import { useHistory } from "react-router-dom";

function HomeButton() {
  let history = useHistory();

  function handleClick() {

  return (
    <button type="button" onClick={handleClick}>
      Go home

read more at:

PHP refresh window? equivalent to F5 page reload?

Adding following in the page header works for me:


if($i_wanna_reload_the_full_page_on_top == "yes")
$reloadneeded = "1";
$reloadneeded = "0";

if($reloadneeded > 0)
<script type="text/javascript">

Set space between divs

You need a gutter between two div gutter can be made as following

margin(gutter) = width - gutter size E.g margin = calc(70% - 2em)

<body bgcolor="gray">
<section id="main">
        <div id="left">
            Something here     
        <div id="right">
                Someone there
    font-size: 10px;

#main div{
    float: left;
    width: calc(50% - 1.5em);
    margin-left: 1.5em;

How to Generate unique file names in C#

I wrote a class specifically for doing this. It's initialized with a "base" part (defaults to a minute-accurate timestamp) and after that appends letters to make unique names. So, if the first stamp generated is 1907101215a, the second would be 1907101215b, then 1907101215c, et cetera.

If I need more than 25 unique stamps then I use unary 'z's to count 25's. So, it goes 1907101215y, 1907101215za, 1907101215zb, ... 1907101215zy, 1907101215zza, 1907101215zzb, and so forth. This guarantees that the stamps will always sort alphanumerically in the order they were generated (as long as the next character after the stamp isn't a letter).

It isn't thread-safe, doesn't automatically update the time, and quickly bloats if you need hundreds of stamps, but I find it sufficient for my needs.

/// <summary>
/// Class for generating unique stamps (for filenames, etc.)
/// </summary>
/// <remarks>
/// Each time ToString() is called, a unique stamp is generated.
/// Stamps are guaranteed to sort alphanumerically in order of generation.
/// </remarks>
public class StampGenerator
  /// <summary>
  /// All the characters which could be the last character in the stamp.
  /// </summary>
  private static readonly char[] _trailingChars =
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
    'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
    'u', 'v', 'w', 'x', 'y'

  /// <summary>
  /// How many valid trailing characters there are.
  /// </summary>
  /// <remarks>Should always equal _trailingChars.Length</remarks>
  public const int TRAILING_RANGE = 25;

  /// <summary>
  /// Maximum length of the stamp. Hard-coded for laziness.
  /// </summary>
  public const int MAX_LENGTH_STAMP = 28;

  /// <summary>
  /// Base portion of the stamp. Will be constant between calls.
  /// </summary>
  /// <remarks>
  /// This is intended to uniquely distinguish between instances.
  /// Default behavior is to generate a minute-accurate timestamp.
  /// </remarks>
  public string StampBase { get; }

  /// <summary>
  /// Number of times this instance has been called.
  /// </summary>
  public int CalledTimes { get; private set; }

  /// <summary>
  /// Maximum number of stamps that can be generated with a given base.
  /// </summary>
  public int MaxCalls { get; }

  /// <summary>
  /// Number of stamps remaining for this instance.
  /// </summary>
  public int RemainingCalls { get { return MaxCalls - CalledTimes; } }

  /// <summary>
  /// Instantiate a StampGenerator with a specific base.
  /// </summary>
  /// <param name="stampBase">Base of stamp.</param>
  /// <param name="calledTimes">
  /// Number of times this base has already been used.
  /// </param>
  public StampGenerator(string stampBase, int calledTimes = 0)
    if (stampBase == null)
      throw new ArgumentNullException("stampBase");
    else if (Regex.IsMatch(stampBase, "[^a-zA-Z_0-9 \\-]"))
      throw new ArgumentException("Invalid characters in Stamp Base.",
    else if (stampBase.Length >= MAX_LENGTH_STAMP - 1)
      throw new ArgumentException(
        string.Format("Stamp Base too long. (Length {0} out of {1})",
                      stampBase.Length, MAX_LENGTH_STAMP - 1), "stampBase");
    else if (calledTimes < 0)
      throw new ArgumentOutOfRangeException(
        "calledTimes", calledTimes, "calledTimes cannot be negative.");
      int maxCalls = TRAILING_RANGE * (MAX_LENGTH_STAMP - stampBase.Length);
      if (calledTimes >= maxCalls)
        throw new ArgumentOutOfRangeException(
          "calledTimes", calledTimes, string.Format(
            "Called Times too large; max for stem of length {0} is {1}.",
            stampBase.Length, maxCalls));
        StampBase = stampBase;
        CalledTimes = calledTimes;
        MaxCalls = maxCalls;

  /// <summary>
  /// Instantiate a StampGenerator with default base string based on time.
  /// </summary>
  public StampGenerator() : this(DateTime.Now.ToString("yMMddHHmm")) { }

  /// <summary>
  /// Generate a unique stamp.
  /// </summary>
  /// <remarks>
  /// Stamp values are orered like this:
  /// a, b, ... x, y, za, zb, ... zx, zy, zza, zzb, ...
  /// </remarks>
  /// <returns>A unique stamp.</returns>
  public override string ToString()
    int zCount = CalledTimes / TRAILING_RANGE;
    int trailing = CalledTimes % TRAILING_RANGE;
    int length = StampBase.Length + zCount + 1;

    if (length > MAX_LENGTH_STAMP)
      throw new InvalidOperationException(
        "Stamp length overflown! Cannot generate new stamps.");
      CalledTimes = CalledTimes + 1;
      var builder = new StringBuilder(StampBase, length);
      builder.Append('z', zCount);
      return builder.ToString();

How to do integer division in javascript (Getting division answer in int not float)?

var answer = Math.floor(x)

I sincerely hope this will help future searchers when googling for this common question.

Get child Node of another Node, given node name

You should read it recursively, some time ago I had the same question and solve with this code:

public void proccessMenuNodeList(NodeList nl, JMenuBar menubar) {
    for (int i = 0; i < nl.getLength(); i++) {
        proccessMenuNode(nl.item(i), menubar);

public void proccessMenuNode(Node n, Container parent) {
    Element element = (Element) n;
    String type = element.getAttribute("type");
    String name = element.getAttribute("name");
    if (type.equals("menu")) {
        NodeList nl = element.getChildNodes();
        JMenu menu = new JMenu(name);

        for (int i = 0; i < nl.getLength(); i++)
            proccessMenuNode(nl.item(i), menu);

    } else if (type.equals("item")) {
        JMenuItem item = new JMenuItem(name);

Probably you can adapt it for your case.

How to count digits, letters, spaces for a string in Python?

You shouldn't be setting x = []. That is setting an empty list to your inputted parameter. Furthermore, use python's for i in x syntax as follows:

for i in x:
    if i.isalpha():
    elif i.isnumeric():
    elif i.isspace():

MySQL Multiple Left Joins

You're missing a GROUP BY clause:

SELECT, users.username, news.title,, news.body, COUNT(
FROM news
ON news.user_id =
LEFT JOIN comments
ON comments.news_id =

The left join is correct. If you used an INNER or RIGHT JOIN then you wouldn't get news items that didn't have comments.

Detected both log4j-over-slf4j.jar AND slf4j-log4j12.jar on the class path, preempting StackOverflowError.

SBT solution stated above did not work for me. What worked for me is excluding slf4j-log4j12

//dependencies with exclusions_x000D_
libraryDependencies ++= Seq(_x000D_

Maven 3 warnings about build.plugins.plugin.version

get the latest version information from:

click on the latest version (or the one you'd like to use) and you'll see the the dependency info (as of 2019-05 it's 3.8.1):

<!-- -->

you might want to use the version tag and the comment for your plugin tag.

<!-- -->
        <source />
        <target />

if you like you can modify your pom to have the version information in the properties tag as outlined in another answer.

How to hide scrollbar in Firefox?

Just in case, if someone is looking for a hack to somehow make the scrollbar invisible in firefox(79.0).

Here's a solution that successfully works for Chrome, IE, Safari, and makes the scrollbar transparent in Firefox. None of the above worked for firefox(79.0) in truly hiding the scrollbar.

Please if anyone finds a way to do it without changing the color, it will be very helpful. Pls comment below.

.scrollhost::-webkit-scrollbar {
  display: none;

.scrollhost ::-moz-scrollbar {
  display: none;
.scrollhost {
  overflow: auto;
  -ms-overflow-style: none;
  scrollbar-color: transparent transparent; /*just hides the scrollbar for firefox */

Linux command (like cat) to read a specified quantity of characters

head or tail can do it as well:

head -c X

Prints the first X bytes (not necessarily characters if it's a UTF-16 file) of the file. tail will do the same, except for the last X bytes.

This (and cut) are portable.

Multipart forms from C# client

Building on dnolans example, this is the version I could actually get to work (there were some errors with the boundary, encoding wasn't set) :-)

To send the data:

HttpWebRequest oRequest = null;
oRequest = (HttpWebRequest)HttpWebRequest.Create("");
oRequest.ContentType = "multipart/form-data; boundary=" + PostData.boundary;
oRequest.Method = "POST";
PostData pData = new PostData();
Encoding encoding = Encoding.UTF8;
Stream oStream = null;

/* ... set the parameters, read files, etc. IE:
   pData.Params.Add(new PostDataParam("email", "[email protected]", PostDataParamType.Field));
   pData.Params.Add(new PostDataParam("fileupload", "filename.txt", "filecontents" PostDataParamType.File));

byte[] buffer = encoding.GetBytes(pData.GetPostData());

oRequest.ContentLength = buffer.Length;

oStream = oRequest.GetRequestStream();
oStream.Write(buffer, 0, buffer.Length);

HttpWebResponse oResponse = (HttpWebResponse)oRequest.GetResponse();

The PostData class should look like:

public class PostData
    // Change this if you need to, not necessary
    public static string boundary = "AaB03x";

    private List<PostDataParam> m_Params;

    public List<PostDataParam> Params
        get { return m_Params; }
        set { m_Params = value; }

    public PostData()
        m_Params = new List<PostDataParam>();

    /// <summary>
    /// Returns the parameters array formatted for multi-part/form data
    /// </summary>
    /// <returns></returns>
    public string GetPostData()
        StringBuilder sb = new StringBuilder();
        foreach (PostDataParam p in m_Params)
            sb.AppendLine("--" + boundary);

            if (p.Type == PostDataParamType.File)
                sb.AppendLine(string.Format("Content-Disposition: file; name=\"{0}\"; filename=\"{1}\"", p.Name, p.FileName));
                sb.AppendLine("Content-Type: application/octet-stream");
                sb.AppendLine(string.Format("Content-Disposition: form-data; name=\"{0}\"", p.Name));

        sb.AppendLine("--" + boundary + "--");

        return sb.ToString();

public enum PostDataParamType

public class PostDataParam
    public PostDataParam(string name, string value, PostDataParamType type)
        Name = name;
        Value = value;
        Type = type;

    public PostDataParam(string name, string filename, string value, PostDataParamType type)
        Name = name;
        Value = value;
        FileName = filename;
        Type = type;

    public string Name;
    public string FileName;
    public string Value;
    public PostDataParamType Type;

How to cd into a directory with space in the name?

To change to a directory with spaces on the name you just have to type like this:

cd My\ Documents

Hit enter and you will be good

Display encoded html with razor

I store encoded HTML in the database.

Imho you should not store your data html-encoded in the database. Just store in plain text (not encoded) and just display your data like this and your html will be automatically encoded:

<div class='content'>

XAMPP on Windows - Apache not starting

I had my Apache service not start same as MySQL one. Please follow these steps if none of above tips works :

  1. Open regedit.exe on any windows this available . Run as administrator. (Only on windows 7 and later editions )
    1. Go to local machine/system/controlset001/services
    2. Find and delete folders of services apache and mysql .
    3. Uninstall xampp . Delete folder of xampp.
    4. Restart computer and reinstall Xampp . After that your Xampp apache and Mysql should work.

Note: Ports 80 and 443 must be unused by any program. 
      If it is in use . Just edit ports. There is a lot of tutorials about that .

C++ Best way to get integer division and remainder

std::div returns a structure with both result and remainder.

How to change background Opacity when bootstrap modal is open

You can override the modal-backdrop opacity in your stylesheet [take note of the .in class] {
    opacity: 0.9;

How to scroll to top of a div using jQuery?

I don't know why but you have to add a setTimeout with at least for me 200ms:

setTimeout( function() {$("#DIV_ID").scrollTop(0)}, 200 );

Tested with Firefox / Chrome / Edge.

how to get the selected index of a drop down

<select name="CCards" id="ccards">
    <option value="0">Select Saved Payment Method:</option>
    <option value="1846">test  xxxx1234</option>
    <option value="1962">test2  xxxx3456</option>

<script type="text/javascript">

    /** Jquery **/
    var selectedValue = $('#ccards').val();

    //** Regular Javascript **/
    var selectedValue2 = document.getElementById('ccards').value;


AJAX post error : Refused to set unsafe header "Connection"

Remove these two lines:

xmlHttp.setRequestHeader("Content-length", params.length);
xmlHttp.setRequestHeader("Connection", "close");

XMLHttpRequest isn't allowed to set these headers, they are being set automatically by the browser. The reason is that by manipulating these headers you might be able to trick the server into accepting a second request through the same connection, one that wouldn't go through the usual security checks - that would be a security vulnerability in the browser.

How to prevent XSS with HTML/PHP?

In order of preference:

  1. If you are using a templating engine (e.g. Twig, Smarty, Blade), check that it offers context-sensitive escaping. I know from experience that Twig does. {{ var|e('html_attr') }}
  2. If you want to allow HTML, use HTML Purifier. Even if you think you only accept Markdown or ReStructuredText, you still want to purify the HTML these markup languages output.
  3. Otherwise, use htmlentities($var, ENT_QUOTES | ENT_HTML5, $charset) and make sure the rest of your document uses the same character set as $charset. In most cases, 'UTF-8' is the desired character set.

Also, make sure you escape on output, not on input.

Android. Fragment getActivity() sometimes returns null

I know this is a old question but i think i must provide my answer to it because my problem was not solved by others.

first of all : i was dynamically adding fragments using fragmentTransactions. Second: my fragments were modified using AsyncTasks (DB queries on a server). Third: my fragment was not instantiated at activity start Fourth: i used a custom fragment instantiation "create or load it" in order to get the fragment variable. Fourth: activity was recreated because of orientation change

The problem was that i wanted to "remove" the fragment because of the query answer, but the fragment was incorrectly created just before. I don't know why, probably because of the "commit" be done later, the fragment was not added yet when it was time to remove it. Therefore getActivity() was returning null.

Solution : 1)I had to check that i was correctly trying to find the first instance of the fragment before creating a new one 2)I had to put serRetainInstance(true) on that fragment in order to keep it through orientation change (no backstack needed therefore no problem) 3)Instead of "recreating or getting old fragment" just before "remove it", I directly put the fragment at activity start. Instantiating it at activity start instead of "loading" (or instantiating) the fragment variable before removing it prevented getActivity problems.

How to check if an email address exists without sending an email?

There are two methods you can sometimes use to determine if a recipient actually exists:

  1. You can connect to the server, and issue a VRFY command. Very few servers support this command, but it is intended for exactly this. If the server responds with a 2.0.0 DSN, the user exists.

    VRFY user
  2. You can issue a RCPT, and see if the mail is rejected.

    MAIL FROM:<>
    RCPT TO:<user@domain>

If the user doesn't exist, you'll get a 5.1.1 DSN. However, just because the email is not rejected, does not mean the user exists. Some server will silently discard requests like this to prevent enumeration of their users. Other servers cannot verify the user and have to accept the message regardless.

There is also an antispam technique called greylisting, which will cause the server to reject the address initially, expecting a real SMTP server would attempt a re-delivery some time later. This will mess up attempts to validate the address.

Honestly, if you're attempting to validate an address the best approach is to use a simple regex to block obviously invalid addresses, and then send an actual email with a link back to your system that will validate the email was received. This also ensures that they user entered their actual email, not a slight typo that happens to belong to somebody else.

Access to build environment variables from a groovy script in a Jenkins build step (Windows)

On jenkins 2.x, with groovy plugin 2.0, running SystemGroovyScript I managed to get to build variables, as below:

def build = this.getProperty('binding').getVariable('build')
def listener = this.getProperty('binding').getVariable('listener')
def env = build.getEnvironment(listener)
println env.MY_VARIABLE

If you are using goovy from file, simple System.getenv('MY_VARIABLE') is sufficient

Access-Control-Allow-Origin error sending a jQuery Post to Google API's

I had exactly the same issue and it was not cross domain but the same domain. I just added this line to the php file which was handling the ajax request.

<?php header('Access-Control-Allow-Origin: *'); ?>

It worked like a charm. Thanks to the poster

Convert an ArrayList to an object array

You can use this code

ArrayList<TypeA> a = new ArrayList<TypeA>();
Object[] o = a.toArray();

Then if you want that to get that object back into TypeA just check it with instanceOf method.

Grep characters before and after match?

3 characters before and 4 characters after

$> echo "some123_string_and_another" | grep -o -P '.{0,3}string.{0,4}'

Match everything except for specified strings

Matching any text but those matching a pattern is usually achieved with splitting the string with the regex pattern.


  • - Regex.Split(text, @"red|green|blue") or, to get rid of empty values, Regex.Split(text, @"red|green|blue").Where(x => !string.IsNullOrEmpty(x)) (see demo)
  • - Regex.Split(text, "red|green|blue") or, to remove empty items, Regex.Split(text, "red|green|blue").Where(Function(s) Not String.IsNullOrWhitespace(s)) (see demo, or this demo where LINQ is supported)
  • - text.split(/red|green|blue/) (no need to use g modifier here!) (to get rid of empty values, use text.split(/red|green|blue/).filter(Boolean)), see demo
  • - text.split("red|green|blue"), or - to keep all trailing empty items - use text.split("red|green|blue", -1), or to remove all empty items use more code to remove them (see demo)
  • - Similar to Java, text.split(/red|green|blue/), to get all trailing items use text.split(/red|green|blue/, -1) and to remove all empty items use text.split(/red|green|blue/).findAll {it != ""}) (see demo)
  • - text.split(Regex("red|green|blue")) or, to remove blank items, use text.split(Regex("red|green|blue")).filter{ !it.isBlank() }, see demo
  • - text.split("red|green|blue"), or to keep all trailing empty items, use text.split("red|green|blue", -1) and to remove all empty items, use text.split("red|green|blue").filter(_.nonEmpty) (see demo)
  • - text.split(/red|green|blue/), to get rid of empty values use .split(/red|green|blue/).reject(&:empty?) (and to get both leading and trailing empty items, use -1 as the second argument, .split(/red|green|blue/, -1)) (see demo)
  • - my @result1 = split /red|green|blue/, $text;, or with all trailing empty items, my @result2 = split /red|green|blue/, $text, -1;, or without any empty items, my @result3 = grep { /\S/ } split /red|green|blue/, $text; (see demo)
  • - preg_split('~red|green|blue~', $text) or preg_split('~red|green|blue~', $text, -1, PREG_SPLIT_NO_EMPTY) to output no empty items (see demo)
  • - re.split(r'red|green|blue', text) or, to remove empty items, list(filter(None, re.split(r'red|green|blue', text))) (see demo)
  • - Use regexp.MustCompile("red|green|blue").Split(text, -1), and if you need to remove empty items, use this code. See Go demo.

NOTE: If you patterns contain capturing groups, regex split functions/methods may behave differently, also depending on additional options. Please refer to the appropriate split method documentation then.

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

One minor difference is what they convert of undefined or null,

Number() Or Number(null) // returns 0


parseInt() Or parseInt(null) // returns NaN

https with WCF error: "Could not find base address that matches scheme https"

I was using webHttpBinding and forgot to dicate the security mode of "Transport" on the binding configuration which caused the error:

    <binding name="MyWCFServiceEndpoint">
      <security mode="Transport" />

Adding this in configuration fixed the problem.

JavaScript code for getting the selected value from a combo box

I use this

var e = document.getElementById('ticket_category_clone').value;

Notice that you don't need the '#' character in javascript.

    function check () {

    var str = document.getElementById('ticket_category_clone').value;

      if (str==="Hardware")
        SPICEWORKS.utils.addStyle('#ticket_c_hardware_clone{display: none !important;}');


How to get the current URL within a Django template?

For Django > 3 I do not change settings or anything. I add the below code in the template file.

{{ request.path }}  #  -without GET parameters 
{{ request.get_full_path }}  # - with GET parameters

and in pass request variable to the template file.

def view_node_taxon(request, cid):
    showone = get_object_or_404(models.taxon, id = cid)
    context = {'showone':showone,'request':request}
    mytemplate  = loader.get_template('taxon/node.html')
    html = mytemplate.render(context)
    return HttpResponse(html)

Windows- Pyinstaller Error "failed to execute script " When App Clicked

I was getting this error for a different reason than those listed here, and could not find the solution easily, so I figured I would post here.

Hopefully this is helpful to someone.

My issue was with referencing files in the program. It was not able to find the file listed, because when I was coding it I had the file I wanted to reference in the top level directory and just called


when I was calling the files.

pyinstaller did not like this, because even when I was running it from the same folder, it was expecting a full path:


Once I changed all of my paths, to the full version of their path, it fixed this issue.

Background blur with CSS

You could make it through iframes... I made something, but my only problem for now is syncing those divs to scroll simultaneous... its terrible way, because its like you load 2 websites, but the only way I found... you could also work with divs and overflow I guess...

How do I toggle an ng-show in AngularJS based on a boolean?

Basically I solved it by NOT-ing the isReplyFormOpen value whenever it is clicked:

<a ng-click="isReplyFormOpen = !isReplyFormOpen">Reply</a>

<div ng-init="isReplyFormOpen = false" ng-show="isReplyFormOpen" id="replyForm">
    <!-- Form -->

Concat all strings inside a List<string> using LINQ

using System.Linq;

public class Person
  string FirstName { get; set; }
  string LastName { get; set; }

List<Person> persons = new List<Person>();

string listOfPersons = string.Join(",", persons.Select(p => p.FirstName));

How to make a JTable non-editable

create new DefaultCellEditor class :

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

and use setCellEditor :

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

Retrofit 2 - Dynamic URL

You can use the encoded flag on the @Path annotation:

public interface APIService {
  Call<Users> getUsers(@Path(value = "fullUrl", encoded = true) String fullUrl);
  • This will prevent the replacement of / with %2F.
  • It will not save you from ? being replaced by %3F, however, so you still can't pass in dynamic query strings.

Compile c++14-code with g++

For gcc 4.8.4 you need to use -std=c++1y in later versions, looks like starting with 5.2 you can use -std=c++14.

If we look at the gcc online documents we can find the manuals for each version of gcc and we can see by going to Dialect options for 4.9.3 under the GCC 4.9.3 manual it says:


The next revision of the ISO C++ standard, tentatively planned for 2014. Support is highly experimental, and will almost certainly change in incompatible ways in future releases.

So up till 4.9.3 you had to use -std=c++1y while the gcc 5.2 options say:

‘c++14’ ‘c++1y’

The 2014 ISO C++ standard plus amendments. The name ‘c++1y’ is deprecated.

It is not clear to me why this is listed under Options Controlling C Dialect but that is how the documents are currently organized.

Execution failed for task ':app:compileDebugJavaWithJavac' Android Studio 3.1 Update

  • My solution is simple, don't look at the error notification in Build - Run tasks (which should be Execution failed for task ':app:compileDebugJavaWithJavac')

  • Just fix all errors in the Java Compiler section below it.

enter image description here

Design Documents (High Level and Low Level Design Documents)

High-Level Design (HLD) involves decomposing a system into modules, and representing the interfaces & invocation relationships among modules. An HLD is referred to as software architecture.

LLD, also known as a detailed design, is used to design internals of the individual modules identified during HLD i.e. data structures and algorithms of the modules are designed and documented.

Now, HLD and LLD are actually used in traditional Approach (Function-Oriented Software Design) whereas, in OOAD, the system is seen as a set of objects interacting with each other.

As per the above definitions, a high-level design document will usually include a high-level architecture diagram depicting the components, interfaces, and networks that need to be further specified or developed. The document may also depict or otherwise refer to work flows and/or data flows between component systems.

Class diagrams with all the methods and relations between classes come under LLD. Program specs are covered under LLD. LLD describes each and every module in an elaborate manner so that the programmer can directly code the program based on it. There will be at least 1 document for each module. The LLD will contain - a detailed functional logic of the module in pseudo code - database tables with all elements including their type and size - all interface details with complete API references(both requests and responses) - all dependency issues - error message listings - complete inputs and outputs for a module.

What does 'super' do in Python?

Super() in a nutshell

  • Every Python instance has a class that created it.
  • Every class in Python has a chain of ancestor classes.
  • A method using super() delegates work to the next ancestor in the chain for the instance's class.


This small example covers all the interesting cases:

class A:
    def m(self):

class B(A):
    def m(self):
        print('B start')
        print('B end')
class C(A):
    def m(self):
        print('C start')
        print('C end')

class D(B, C):
    def m(self):
        print('D start')
        print('D end')

The exact order of calls in determined by the instance the method is called from:

>>> a = A()
>>> b = B()
>>> c = C()
>>> d = D()

For instance a, there is no super call:

>>> a.m()

For instance b, the ancestor chain is B -> A -> object:

>>> type(b).__mro__   
(<class '__main__.B'>, <class '__main__.A'>, <class 'object'>)

>>> b.m()
B start
B end

For instance c, the ancestor chain is C -> A -> object:

>>> type(c).__mro__   
(<class '__main__.C'>, <class '__main__.A'>, <class 'object'>)

>>> b.m()
C start
C end

For instance d, the ancestor chain is more interesting D -> B -> C -> A -> object:

>>> type(d).__mro__
(<class '__main__.D'>, <class '__main__.B'>, <class '__main__.C'>, <class '__main__.A'>, <class 'object'>)

>>> d.m()
D start
B start
C start
C end
B end
D end

More information

Having answered the question of "What does super do in Python?", the next question is how to use it effectively. See this step-by-step tutorial or this 45 minute video.

How to add,set and get Header in request of HttpClient?

You can test-drive this code exactly as is using the public GitHub API (don't go over the request limit):

public class App {

    public static void main(String[] args) throws IOException {

        CloseableHttpClient client = HttpClients.custom().build();

        // (1) Use the new Builder API (from v4.3)
        HttpUriRequest request = RequestBuilder.get()
                // (2) Use the included enum
                .setHeader(HttpHeaders.CONTENT_TYPE, "application/json")
                // (3) Or your own
                .setHeader("Your own very special header", "value")

        CloseableHttpResponse response = client.execute(request);

        // (4) How to read all headers with Java8
        List<Header> httpHeaders = Arrays.asList(response.getAllHeaders());;

        // close client and response

Script parameters in Bash

In bash $1 is the first argument passed to the script, $2 second and so on

/usr/local/bin/abbyyocr9 -rl Swedish -if "$1" -of "$2" 2>&1

So you can use:

./ some_source_file.png destination_file.txt

Explanation on double quotes;

consider three scripts:

bash $1

# cat
bash "$1"

echo "1-$1" "2-$2"

Now invoke:

$ bash "a b"
1-a 2-b

$ bash "a b"
1-a b 2-

When you invoke "a b" then it invokes a b (two arguments), and with "a b" it invokes "a b" (1 argument). Always have in mind how parameters are passed and expaned in bash, it will save you a lot of headache.

Select Row number in postgres

SELECT tab.*,
    row_number() OVER () as rnum
  FROM tab;

Here's the relevant section in the docs.

P.S. This, in fact, fully matches the answer in the referenced question.

Android Studio - Failed to apply plugin [id '']

I found the simplest answer to this.

Just go file and change the enableUnitTestBinaryResources from true to false


The snapshot is shown below

enter image description here

How to use a typescript enum value in an Angular2 ngSwitch statement

If using the 'typetable reference' approach (from @Carl G) and you're using multiple type tables you might want to consider this way :

export default class AppComponent {

  // Store a reference to the enums (must be public for --AOT to work)
  public TT = { 
       CellType: CellType, 
       CatType: CatType, 
       DogType: DogType 


  dog = DogType.GoldenRetriever; 

Then access in your html file with

{{ TT.DogType[dog] }}   => "GoldenRetriever"

I favor this approach as it makes it clear you're referring to a typetable, and also avoids unnecessary pollution of your component file.

You can also put a global TT somewhere and add enums to it as needed (if you want this you may as well make a service as shown by @VincentSels answer). If you have many many typetables this may become cumbersome.

Also you always rename them in your declaration to get a shorter name.

Deploying website: 500 - Internal server error

In my case, I put a mistake in my web.config file. The application key somehow was put under the <appSettings> tag. But I wonder why it doesn't display a configuration error. The error 500 is too generic for investigating the problem.

How to read the post request parameters using JavaScript

We can collect the form params submitted using POST with using serialize concept.

Try this:


Just enclose it alert, it displays all the parameters including hidden.

How To Accept a File POST

Here are two ways to accept a file. One using in memory provider MultipartMemoryStreamProvider and one using MultipartFormDataStreamProvider which saves to a disk. Note, this is only for one file upload at a time. You can certainty extend this to save multiple-files. The second approach can support large files. I've tested files over 200MB and it works fine. Using in memory approach does not require you to save to disk, but will throw out of memory exception if you exceed a certain limit.

private async Task<Stream> ReadStream()
    Stream stream = null;
    var provider = new MultipartMemoryStreamProvider();
    await Request.Content.ReadAsMultipartAsync(provider);
    foreach (var file in provider.Contents)
        var buffer = await file.ReadAsByteArrayAsync();
        stream = new MemoryStream(buffer);

    return stream;

private async Task<Stream> ReadLargeStream()
    Stream stream = null;
    string root = Path.GetTempPath();
    var provider = new MultipartFormDataStreamProvider(root);
    await Request.Content.ReadAsMultipartAsync(provider);
    foreach (var file in provider.FileData)
        var path = file.LocalFileName;
        byte[] content = File.ReadAllBytes(path);
        stream = new MemoryStream(content);

    return stream;

Using jQuery's ajax method to retrieve images as a blob

A big thank you to @Musa and here is a neat function that converts the data to a base64 string. This may come handy to you when handling a binary file (pdf, png, jpeg, docx, ...) file in a WebView that gets the binary file but you need to transfer the file's data safely into your app.

// runs a get/post on url with post variables, where:
// url ... your url
// post ... {'key1':'value1', 'key2':'value2', ...}
//          set to null if you need a GET instead of POST req
// done ... function(t) called when request returns
function getFile(url, post, done)
   var postEnc, method;
   if (post == null)
      postEnc = '';
      method = 'GET';
      method = 'POST';
      postEnc = new FormData();
      for(var i in post)
         postEnc.append(i, post[i]);
   var xhr = new XMLHttpRequest();
   xhr.onreadystatechange = function() {
      if (this.readyState == 4 && this.status == 200)
         var res = this.response;
         var reader = new window.FileReader();
         reader.onloadend = function() { done(reader.result.split('base64,')[1]); }
   }, url);
   xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
   xhr.responseType = 'blob';

How to merge remote changes at GitHub?

You probably have changes on github that you never merged. Try git pull to fetch and merge the changes, then you should be able to push. Sorry if I misunderstood your question.

How is malloc() implemented internally?

It's also important to realize that simply moving the program break pointer around with brk and sbrk doesn't actually allocate the memory, it just sets up the address space. On Linux, for example, the memory will be "backed" by actual physical pages when that address range is accessed, which will result in a page fault, and will eventually lead to the kernel calling into the page allocator to get a backing page.

Text to speech(TTS)-Android

Text to speech is built into Android 1.6+. Here is a simple example of how to do it.

TextToSpeech tts = new TextToSpeech(this, this);
tts.speak("Text to say aloud", TextToSpeech.QUEUE_ADD, null);

More info:

Here are instructions on how to download sample code from the Android SDK Manager:

  1. Launch the Android SDK Manager.

    a. On Windows, double-click the SDK Manager.exe file at the root of the Android SDK directory.

    b. On Mac or Linux, open a terminal to the tools/ directory in the Android SDK, then execute android sdk.

  2. Expand the list of packages for the latest Android platform.

  3. Select and download Samples for SDK. When the download is complete, you can find the source code for all samples at this location:


(i.e. \android-sdk-windows\samples\android-16\ApiDemos\src\com\example\android\apis\app\

Python: How to create a unique file name?

In case you need short unique IDs as your filename, try shortuuid, shortuuid uses lowercase and uppercase letters and digits, and removing similar-looking characters such as l, 1, I, O and 0.

>>> import shortuuid
>>> shortuuid.uuid()
>>> len(ui)

compared to

>>> import uuid
>>> unique_filename = str(uuid.uuid4())
>>> len(unique_filename)
>>> unique_filename

echo that outputs to stderr

If you don't mind logging the message also to syslog, the not_so_ugly way is:

logger -s $msg

The -s option means: "Output the message to standard error as well as to the system log."