Programs & Examples On #Visual studio shell

Visual Studio Shell is used to create custom tool having an integrated development environment (IDE) similar to VS.

ICommand MVVM implementation

I've just created a little example showing how to implement commands in convention over configuration style. However it requires Reflection.Emit() to be available. The supporting code may seem a little weird but once written it can be used many times.


public class SampleViewModel: BaseViewModelStub
    public string Name { get; set; }

    public void HelloWorld()
        MessageBox.Show("Hello World!");

    public void Print()
        MessageBox.Show(String.Concat("Hello, ", Name, "!"), "SampleViewModel");

    public bool CanPrint()
        return !String.IsNullOrEmpty(Name);


UPDATE: now there seem to exist some libraries like that solve the problem of ICommand boilerplate code.

How to ignore deprecation warnings in Python

You should just fix your code but just in case,

import warnings
warnings.filterwarnings("ignore", category=DeprecationWarning) 

How do I show the number keyboard on an EditText in android?


Pointer-to-pointer dynamic two-dimensional array

this can be done this way

  1. I have used Operator Overloading
  2. Overloaded Assignment
  3. Overloaded Copy Constructor

     * Soumil Nitin SHah
     * Github:
    #include <iostream>
    using namespace std;
            class Matrix{
         * Declare the Row and Column
        int r_size;
        int c_size;
        int **arr;
         * Constructor and Destructor
        Matrix(int r_size, int c_size):r_size{r_size},c_size{c_size}
            arr = new int*[r_size];
            // This Creates a 2-D Pointers
            for (int i=0 ;i < r_size; i++)
                arr[i] = new int[c_size];
            // Initialize all the Vector to 0 initially
            for (int row=0; row<r_size; row ++)
                for (int column=0; column < c_size; column ++)
                    arr[row][column] = 0;
            std::cout << "Constructor -- creating Array Size ::" << r_size << " " << c_size << endl;
            std::cout << "Destructpr  -- Deleting  Array Size ::" << r_size <<" " << c_size << endl;
        Matrix(const Matrix &source):Matrix(source.r_size, source.c_size)
            for (int row=0; row<source.r_size; row ++)
                for (int column=0; column < source.c_size; column ++)
                    arr[row][column] = source.arr[row][column];
            cout << "Copy Constructor " << endl;
         * Operator Overloading
        friend std::ostream &operator<<(std::ostream &os, Matrix & rhs)
            int rowCounter = 0;
            int columnCOUNTER = 0;
            int globalCounter = 0;
            for (int row =0; row < rhs.r_size; row ++)
                for (int column=0; column < rhs.c_size ; column++)
                    globalCounter = globalCounter + 1;
                rowCounter = rowCounter + 1;
            os << "Total There are " << globalCounter << " Elements" << endl;
            os << "Array Elements are as follow -------" << endl;
            os << "\n";
            for (int row =0; row < rhs.r_size; row ++)
                for (int column=0; column < rhs.c_size ; column++)
                    os << rhs.arr[row][column] << " ";
            os <<"\n";
            return os;
        void operator()(int row, int column , int Data)
            arr[row][column] = Data;
        int &operator()(int row, int column)
            return arr[row][column];
        Matrix &operator=(Matrix &rhs)
                    cout << "Assingment Operator called " << endl;cout <<"\n";
                    if(this == &rhs)
                        return *this;
                    } else
                        delete [] arr;
                            arr = new int*[r_size];
                            // This Creates a 2-D Pointers
                            for (int i=0 ;i < r_size; i++)
                                arr[i] = new int[c_size];
                            // Initialize all the Vector to 0 initially
                            for (int row=0; row<r_size; row ++)
                                for (int column=0; column < c_size; column ++)
                                    arr[row][column] = rhs.arr[row][column];
                            return *this;
                int main()
        Matrix m1(3,3);         // Initialize Matrix 3x3
        cout << m1;cout << "\n";
        cout << m1;cout <<"\n";             // print Matrix
        cout << "Element at Position (1,2) : " << m1(1,2) << endl;
        Matrix m2(3,3);
        m2 = m1;
        cout << m2;cout <<"\n";
        return 0;

Most popular screen sizes/resolutions on Android phones

Here is a list of almost all resolutions of tablets, with the most common ones in bold :




Happy designing .. ! :)

How to convert hex string to Java string?

You can go from String (hex) to byte array to String as UTF-8(?). Make sure your hex string does not have leading spaces and stuff.

public static byte[] hexStringToByteArray(String hex) {
    int l = hex.length();
    byte[] data = new byte[l / 2];
    for (int i = 0; i < l; i += 2) {
        data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
                + Character.digit(hex.charAt(i + 1), 16));
    return data;


String b = "0xfd00000aa8660b5b010006acdc0100000101000100010000";
byte[] bytes = hexStringToByteArray(b);
String st = new String(bytes, StandardCharsets.UTF_8);

Excel doesn't update value unless I hit Enter

I ran into this exact problem too. In my case, adding parenthesis around any internal functions (to get them to evaluate first) seemed to do the trick:


=SUM(A1, SUBSTITUTE(A2,"x","3",1), A3) 


=SUM(A1, (SUBSTITUTE(A2,"x","3",1)), A3) 

Exception thrown inside catch block - will it be caught again?

No -- As Chris Jester-Young said, it will be thrown up to the next try-catch in the hierarchy.

How can I listen to the form submit event in javascript?

Why do people always use jQuery when it isn't necessary?
Why can't people just use simple JavaScript?

var ele = /*Your Form Element*/;
    ele.addEventListener("submit", callback, false);  //Modern browsers
}else if(ele.attachEvent){
    ele.attachEvent('onsubmit', callback);            //Old IE

callback is a function that you want to call when the form is being submitted.

About EventTarget.addEventListener, check out this documentation on MDN.

To cancel the native submit event (prevent the form from being submitted), use .preventDefault() in your callback function,

document.querySelector("#myForm").addEventListener("submit", function(e){
        e.preventDefault();    //stop form from submitting

Listening to the submit event with libraries

If for some reason that you've decided a library is necessary (you're already using one or you don't want to deal with cross-browser issues), here's a list of ways to listen to the submit event in common libraries:

  1. jQuery


    Where ele is the form element reference, and callback being the callback function reference. Reference

    <iframe width="100%" height="100%" src="" frameborder="0"></iframe>

  1. AngularJS (1.x)

    <form ng-submit="callback()">
    $scope.callback = function(){ /*...*/ };

    Very straightforward, where $scope is the scope provided by the framework inside your controller. Reference

  2. React

    <form onSubmit={this.handleSubmit}>
    class YourComponent extends Component {
        // stuff
        handleSubmit(event) {
            // do whatever you need here
            // if you need to stop the submit event and 
            // perform/dispatch your own actions
        // more stuff

    Simply pass in a handler to the onSubmit prop. Reference

  3. Other frameworks/libraries

    Refer to the documentation of your framework.


You can always do your validation in JavaScript, but with HTML5 we also have native validation.

<!-- Must be a 5 digit number -->
<input type="number" required pattern="\d{5}">

You don't even need any JavaScript! Whenever native validation is not supported, you can fallback to a JavaScript validator.


What is the difference between "Form Controls" and "ActiveX Control" in Excel 2010?

It's also worth noting that ActiveX controls only work in Windows, whereas Form Controls will work on both Windows and MacOS versions of Excel.

Should I use past or present tense in git commit messages?

It is up to you. Just use the commit message as you wish. But it is easier if you are not switching between times and languages.

And if you develop in a team - it should be discussed and set fixed.

LINQ to SQL - Left Outer Join with multiple join conditions

You need to introduce your join condition before calling DefaultIfEmpty(). I would just use extension method syntax:

from p in context.Periods
join f in context.Facts on equals f.periodid into fg
from fgi in fg.Where(f => f.otherid == 17).DefaultIfEmpty()
where p.companyid == 100
select f.value

Or you could use a subquery:

from p in context.Periods
join f in context.Facts on equals f.periodid into fg
from fgi in (from f in fg
             where f.otherid == 17
             select f).DefaultIfEmpty()
where p.companyid == 100
select f.value

How do I set Tomcat Manager Application User Name and Password for NetBeans?

When you're launching tomcat server from netbeans IDE you need to check in menu "tools->servers" on connection tab for tomcat server - there is catalina base directory. And you need to include something like:

 <role rolename="manager"/>
  <user username="admin" password="admin" roles="manager"/>

at file


or use username automatically generated by IDE with description already placed in this file or on connection tab

For Manager Apps : GUI access:

<role rolename="manager-gui"/>
<user username="tomcat" password="s3cret" roles="manager-gui"/>

A child container failed during start java.util.concurrent.ExecutionException

  1. download commons-logging-1.1.1.jar.
  2. Go to Your project,build path, configure build path, java build path.
  3. Add external jars.. add commons-logging-1.1.1.jar
  4. click on apply, ok
  5. Go to project, properties, Deployment Assembly, Click on add,Java build path entries, next, select commons logging jar,ok,,apply, ok..
  6. Delete server,clean ur proejct, add server, Run your project.

Force to open "Save As..." popup open at text link click for PDF in HTML

Use the download attribute, but take into account that it only works for files hosted in the same origin that your code. It means that users can only download files that are from the origin site, same host.

Download with original filename:

<a href="file link" download target="_blank">Click here to download</a>

Download with 'some_name' as filename:

<a href="file link" download="some_name" target="_blank">Click here to download</a>

Adding target="_blank" we will use a new Tab instead of the actual one, and also it will contribute to the proper behavior of the download attribute in some scenarios.

It follows the same rules as same-origin policy. You can learn more about this policy on the MDN Web Doc same-origin policy page

You can lern more about this download HTML5 attribute on the MDN Web Doc anchor's attributes page.

How to detect page zoom level in all modern browsers?

On Chrome

var ratio = (screen.availWidth / document.documentElement.clientWidth);
var zoomLevel = Number(ratio.toFixed(1).replace(".", "") + "0");

Detect rotation of Android phone in the browser with JavaScript

you can try the solution, compatible with all browser.

Following is orientationchange compatibility pic: compatibility therefore, I author a orientaionchange polyfill, it is a based on @media attribute to fix orientationchange utility library——orientationchange-fix

window.addEventListener('orientationchange', function(){
 if(window.neworientation.current === 'portrait|landscape'){
    // do something……
 } else {
    // do something……
}, false);

Calling @Html.Partial to display a partial view belonging to a different controller

As GvS said, but I also find it useful to use strongly typed views so that I can write something like

@Html.Partial(MVC.Student.Index(), model)

without magic strings.

Port 80 is being used by SYSTEM (PID 4), what is that?

It sounds like IIS is listening to port 80 for HTTP requests.

Try stopping IIS by going into Control Panel/Administrative Tools/Internet Information Services, right-clicking on Default Web Site, and click on the Stop option in the popup menu, and see if the listener on port 80 has cleared.

How to insert a character in a string at a certain position?

int j = 123456;
String x = Integer.toString(j);
x = x.substring(0, 4) + "." + x.substring(4, x.length());

Using other keys for the waitKey() function of opencv

With Ubuntu and C++ I had problems with the Character/Integer cast. I needed to use cv::waitKey()%256 to obtain the correct ASCII value.

How to create materialized views in SQL Server?

For MS T-SQL Server, I suggest looking into creating an index with the "include" statement. Uniqueness is not required, neither is the physical sorting of data associated with a clustered index. The "Index ... Include ()" creates a separate physical data storage automatically maintained by the system. It is conceptually very similar to an Oracle Materialized View.

Flask Error: "Method Not Allowed The method is not allowed for the requested URL"

I had a similar problem when I deployed my Flask app in the IIS. Apparently, IIS does not accept route that include an underline ("_"). When I removed the underline, problem was resolved.

Laravel Redirect Back with() Message

For laravel 5.6.*

While trying some of the provided answers in Laravel 5.6.*, it's clear there has been some improvements which I am going to post here to make things easy for those that could not find a solution with the rest of the answers.


Go to your Controller File and Add this before the class:

use Illuminate\Support\Facades\Redirect;

STEP 2: Add this where you want to return the redirect.

 return Redirect()->back()->with(['message' => 'The Message']);

STEP 3: Go to your blade file and edit as follows

@if (Session::has('message'))
<div class="alert alert-error>{{Session::get('message')}}</div>

Then test and thank me later.

This should work with laravel 5.6.* and possibly 5.7.*

How to fix curl: (60) SSL certificate: Invalid certificate chain

In some systems like your office system, there is sometimes a firewall/security client that is installed for security purpose. Try uninstalling that and then run the command again, it should start the download.

My system had Netskope Client installed and was blocking the ssl communication.

Search in finder -> uninstall netskope, run it, and try installing homebrew:

/bin/bash -c "$(curl -fsSL"

PS: consider installing the security client.

How to deal with a slow SecureRandom generator?

My experience has been only with slow initialization of the PRNG, not with generation of random data after that. Try a more eager initialization strategy. Since they're expensive to create, treat it like a singleton and reuse the same instance. If there's too much thread contention for one instance, pool them or make them thread-local.

Don't compromise on random number generation. A weakness there compromises all of your security.

I don't see a lot of COTS atomic-decay–based generators, but there are several plans out there for them, if you really need a lot of random data. One site that always has interesting things to look at, including HotBits, is John Walker's Fourmilab.

How to find the path of the local git repository when I am possibly in a subdirectory

git rev-parse --show-toplevel

could be enough if executed within a git repo.
From git rev-parse man page:


Show the absolute path of the top-level directory.

For older versions (before 1.7.x), the other options are listed in "Is there a way to get the git root directory in one command?":

git rev-parse --git-dir

That would give the path of the .git directory.

The OP mentions:

git rev-parse --show-prefix

which returns the local path under the git repo root. (empty if you are at the git repo root)

Note: for simply checking if one is in a git repo, I find the following command quite expressive:

git rev-parse --is-inside-work-tree

And yes, if you need to check if you are in a .git git-dir folder:

git rev-parse --is-inside-git-dir

JSON - Iterate through JSONArray

for (int i = 0; i < getArray.length(); i++) {
            JSONObject objects = getArray.getJSONObject(i);
            Iterator key = objects.keys();
            while (key.hasNext()) {
                String k =;
                System.out.println("Key : " + k + ", value : "
                        + objects.getString(k));
            // System.out.println(objects.toString());


Hope this helps someone

Validate a username and password against Active Directory?

very simple solution using DirectoryServices:

using System.DirectoryServices;

//srvr = ldap server, e.g. LDAP://
//usr = user name
//pwd = user password
public bool IsAuthenticated(string srvr, string usr, string pwd)
    bool authenticated = false;

        DirectoryEntry entry = new DirectoryEntry(srvr, usr, pwd);
        object nativeObject = entry.NativeObject;
        authenticated = true;
    catch (DirectoryServicesCOMException cex)
        //not authenticated; reason why is in cex
    catch (Exception ex)
        //not authenticated due to some other exception [this is optional]

    return authenticated;

the NativeObject access is required to detect a bad user/password

Save a file in json format using Notepad++

If you want to save to a specific filename just ignore the provided extensions in Notepad/Word/whatever. Just set the filename.ext in " " and you're done. "Save as type" will be ignored.

enter image description here

Focusable EditText inside ListView

We're trying this on a short list that does not do any view recycling. So far so good.




 * It helps you keep focused.
 * For use as a parent of {@link android.widget.ListView}s that need to use EditText
 * children for inline editing.
public class RitalinLayout extends FrameLayout {
  View sticky;

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

    ViewTreeObserver vto = getViewTreeObserver();

    vto.addOnGlobalFocusChangeListener(new ViewTreeObserver.OnGlobalFocusChangeListener() {
      @Override public void onGlobalFocusChanged(View oldFocus, View newFocus) {
        if (newFocus == null) return;

        View baby = getChildAt(0);

        if (newFocus != baby) {
          ViewParent parent = newFocus.getParent();
          while (parent != null && parent != parent.getParent()) {
            if (parent == baby) {
              sticky = newFocus;
            parent = parent.getParent();

    vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
      @Override public void onGlobalLayout() {
        if (sticky != null) {

Failed to load ApplicationContext (with annotation)

In my case, I had to do the following while running with Junit5

@SpringBootTest(classes = {abc.class}) @ExtendWith(SpringExtension.class

Here abc.class was the class that was being tested

How to manually reload Google Map with JavaScript

You can refresh with this:

map.panBy(0, 0);

Converting milliseconds to minutes and seconds with Javascript

Best is this!

function msToTime(duration) {
var milliseconds = parseInt((duration%1000))
    , seconds = parseInt((duration/1000)%60)
    , minutes = parseInt((duration/(1000*60))%60)
    , hours = parseInt((duration/(1000*60*60))%24);

hours = (hours < 10) ? "0" + hours : hours;
minutes = (minutes < 10) ? "0" + minutes : minutes;
seconds = (seconds < 10) ? "0" + seconds : seconds;

return hours + ":" + minutes + ":" + seconds + "." + milliseconds;

It will return 00:04:21.223 You can format this string then as you wish.

Declare an array in TypeScript

this is how you can create an array of boolean in TS and initialize it with false:

var array: boolean[] = [false, false, false]

or another approach can be:

var array2: Array<boolean> =[false, false, false] 

you can specify the type after the colon which in this case is boolean array

How to print pthread_t

I know, this thread is very old. Having read all above posts, I would like to add one more idea to handle this in a neat way: If you get into the mapping business anyway (mapping pthread_to to an int), you could as well go one step further in readability. Make your pthread_create_wrapper such that it takes a string, too...the name of the thread. I learned to appreciate this "SetThreadName()" feature on windows and windows CE. Advantages: Your ids are not just numbers but you also see, which of your threads has which purpose.

Import SQL dump into PostgreSQL database

I use:

cat /home/path/to/dump/file | psql -h localhost -U <user_name> -d <db_name>

Hope this will help someone.

How to execute an action before close metro app WinJS

If I am not mistaken, it will be onunload event.

"Occurs when the application is about to be unloaded." - MSDN

What do <o:p> elements do anyway?

Couldn't find any official documentation (no surprise there) but according to this interesting article, those elements are injected in order to enable Word to convert the HTML back to fully compatible Word document, with everything preserved.

The relevant paragraph:

Microsoft added the special tags to Word's HTML with an eye toward backward compatibility. Microsoft wanted you to be able to save files in HTML complete with all of the tracking, comments, formatting, and other special Word features found in traditional DOC files. If you save a file in HTML and then reload it in Word, theoretically you don't loose anything at all.

This makes lots of sense.

For your specific question.. the o in the <o:p> means "Office namespace" so anything following the o: in a tag means "I'm part of Office namespace" - in case of <o:p> it just means paragraph, the equivalent of the ordinary <p> tag.

I assume that every HTML tag has its Office "equivalent" and they have more.

Changing Java Date one hour back


Calendar cal = Calendar.getInstance();
// remove next line if you're always using the current time.
cal.add(Calendar.HOUR, -1);
Date oneHourBack = cal.getTime();


new Date(System.currentTimeMillis() - 3600 * 1000);


new LocalDateTime().minusHours(1)

Java 8: java.time.LocalDateTime

Java 8 java.time.Instant

// always in UTC if not timezone set, ChronoUnit.HOURS));
// with timezone, Europe/Berlin for example

Count of "Defined" Array Elements

An array length is not the number of elements in a array, it is the highest index + 1. length property will report correct element count only if there are valid elements in consecutive indices.

var a = [];
a[23] = 'foo';
a.length;  // 24

Saying that, there is no way to exclude undefined elements from count without using any form of a loop.

Why binary_crossentropy and categorical_crossentropy give different performances for the same problem?

You are passing a target array of shape (x-dim, y-dim) while using as loss categorical_crossentropy. categorical_crossentropy expects targets to be binary matrices (1s and 0s) of shape (samples, classes). If your targets are integer classes, you can convert them to the expected format via:

from keras.utils import to_categorical
y_binary = to_categorical(y_int)

Alternatively, you can use the loss function sparse_categorical_crossentropy instead, which does expect integer targets.

model.compile(loss='sparse_categorical_crossentropy', optimizer='adam', metrics=['accuracy'])

org.hibernate.exception.ConstraintViolationException: Could not execute JDBC batch update

You can find your sample code completely here:

Have a look and check the differences. specially the even_id in :

<set name="attendees" cascade="all">
    <key column="event_id"/>
    <one-to-many class="Attendee"/>

Parsing XML with namespace in Python via 'ElementTree'

I've been using similar code to this and have found it's always worth reading the documentation... as usual!

findall() will only find elements which are direct children of the current tag. So, not really ALL.

It might be worth your while trying to get your code working with the following, especially if you're dealing with big and complex xml files so that that sub-sub-elements (etc.) are also included. If you know yourself where elements are in your xml, then I suppose it'll be fine! Just thought this was worth remembering.


ref: "Element.findall() finds only elements with a tag which are direct children of the current element. Element.find() finds the first child with a particular tag, and Element.text accesses the element’s text content. Element.get() accesses the element’s attributes:"

How to convert hex strings to byte values in Java

Looking at the sample I guess you mean that a string array is actually an array of HEX representation of bytes, don't you?

If yes, then for each string item I would do the following:

  1. check that a string consists only of 2 characters
  2. these chars are in '0'..'9' or 'a'..'f' interval (take their case into account as well)
  3. convert each character to a corresponding number, subtracting code value of '0' or 'a'
  4. build a byte value, where first char is higher bits and second char is lower ones. E.g.

    int byteVal = (firstCharNumber << 4) | secondCharNumber;

getResources().getColor() is deprecated

I found that the useful getResources().getColor(R.color.color_name) is deprecated.

It is not deprecated in API Level 21, according to the documentation.

It is deprecated in the M Developer Preview. However, the replacement method (a two-parameter getColor() that takes the color resource ID and a Resources.Theme object) is only available in the M Developer Preview.

Hence, right now, continue using the single-parameter getColor() method. Later this year, consider using the two-parameter getColor() method on Android M devices, falling back to the deprecated single-parameter getColor() method on older devices.

Node.js create folder or use existing

Good way to do this is to use mkdirp module.

$ npm install mkdirp

Use it to run function that requires the directory. Callback is called after path is created or if path did already exists. Error err is set if mkdirp failed to create directory path.

var mkdirp = require('mkdirp');
mkdirp('/tmp/some/path/foo', function(err) { 

    // path exists unless there was an error


JavaScript code for getting the selected value from a combo box

There is an unnecessary hashtag; change the code to this:

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

How to SELECT a dropdown list item by value programmatically

ddlPageSize.Items.FindByValue("25").Selected = true;

angular 4: *ngIf with multiple conditions

Besides the redundant ) this expression will always be true because currentStatus will always match one of these two conditions:

currentStatus !== 'open' || currentStatus !== 'reopen'

perhaps you mean one of

!(currentStatus === 'open' || currentStatus === 'reopen')
(currentStatus !== 'open' && currentStatus !== 'reopen')

Disable ScrollView Programmatically?

to start, i used the Code posted posted in the first Comment but i changed it like this:

    public class LockableScrollView extends ScrollView {

    public LockableScrollView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        // TODO Auto-generated constructor stub
    public LockableScrollView(Context context, AttributeSet attrs) 
        super(context, attrs);

    public LockableScrollView(Context context) 

    // true if we can scroll (not locked)
    // false if we cannot scroll (locked)
    private boolean mScrollable = true;

    public void setScrollingEnabled(boolean enabled) {
        mScrollable = enabled;

    public boolean isScrollable() {
        return mScrollable;

    public boolean onTouchEvent(MotionEvent ev) {
        switch (ev.getAction()) {
            case MotionEvent.ACTION_DOWN:
                // if we can scroll pass the event to the superclass
                if (mScrollable) return super.onTouchEvent(ev);
                // only continue to handle the touch event if scrolling enabled
                return mScrollable; // mScrollable is always false at this point
                return super.onTouchEvent(ev);

public boolean onInterceptTouchEvent(MotionEvent ev) {
    switch (ev.getAction()) {     
    case MotionEvent.ACTION_DOWN:         
        // if we can scroll pass the event to the superclass      
        if (mScrollable) return super.onInterceptTouchEvent(ev);      
        // only continue to handle the touch event if scrolling enabled    
        return mScrollable; // mScrollable is always false at this point     
            return super.onInterceptTouchEvent(ev);      


then i called it in by this way


because i tried


but it said that setIsScrollable is undefined

i hope this will help you

How do I reference a local image in React?

First of all wrap the src in {}

Then if using Webpack; Instead of: <img src={"./logo.jpeg"} />

You may need to use require:

<img src={require('./logo.jpeg')} />

Another option would be to first import the image as such:

import logo from './logo.jpeg'; // with import

or ...

const logo = require('./logo.jpeg); // with require

then plug it in...

<img src={logo} />

I'd recommend this option especially if you're reusing the image source.

How to check if Location Services are enabled?

You can request the location updates and show the dialog together, like GoogleMaps doas also. Here is the code:

googleApiClient = new GoogleApiClient.Builder(getActivity())

LocationRequest locationRequest = LocationRequest.create();
locationRequest.setInterval(30 * 1000);
locationRequest.setFastestInterval(5 * 1000);
LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder()

builder.setAlwaysShow(true); //this is the key ingredient

PendingResult<LocationSettingsResult> result = LocationServices.SettingsApi.checkLocationSettings(googleApiClient,;
result.setResultCallback(new ResultCallback<LocationSettingsResult>() {
    public void onResult(LocationSettingsResult result) {
        final Status status = result.getStatus();
        final LocationSettingsStates state = result.getLocationSettingsStates();
        switch (status.getStatusCode()) {
            case LocationSettingsStatusCodes.SUCCESS:
                // All location settings are satisfied. The client can initialize location
                // requests here.
            case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                // Location settings are not satisfied. But could be fixed by showing the user
                // a dialog.
                try {
                    // Show the dialog by calling startResolutionForResult(),
                    // and check the result in onActivityResult().
                    status.startResolutionForResult(getActivity(), 1000);
                } catch (IntentSender.SendIntentException ignored) {}
            case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                // Location settings are not satisfied. However, we have no way to fix the
                // settings so we won't show the dialog.

If you need more info check the LocationRequest class.

Reading an Excel file in python using pandas

Loading an excel file without explicitly naming a sheet but instead giving the number of the sheet order (often one will simply load the first sheet) goes like:

import pandas as pd
myexcel = pd.ExcelFile("C:/filename.xlsx")
myexcel = myexcel.parse(myexcel.sheet_names[0])

Since .sheet_names returns a list of sheet names, it is easy to load one or more sheets by simply calling the list element(s).

AttributeError: 'module' object has no attribute

For me, the reason for this error was that there was a folder with the same name as the python module I was trying to import.

|-- core  <-- empty directory on the same level as the module that throws the error

And python treated that folder as a python package and tried to import from that empty package "core", not from

Seems like for some reason git left that empty folder during the branches switch

So I just removed that folder and everything worked like a charm

How do I overload the square-bracket operator in C#?

If you mean the array indexer,, You overload that just by writing an indexer property.. And you can overload, (write as many as you want) indexer properties as long as each one has a different parameter signature

public class EmployeeCollection: List<Employee>
    public Employee this[int employeeId]
            foreach(var emp in this)
                if (emp.EmployeeId == employeeId)
                    return emp;

            return null;

    public Employee this[string employeeName]
            foreach(var emp in this)
                if (emp.Name == employeeName)
                    return emp;

            return null;

Excel VBA function to print an array to the workbook

As others have suggested, you can directly write a 2-dimensional array into a Range on sheet, however if your array is single-dimensional then you have two options:

  1. Convert your 1D array into a 2D array first, then print it on sheet (as a Range).
  2. Convert your 1D array into a string and print it in a single cell (as a String).

Here is an example depicting both options:

Sub PrintArrayIn1Cell(myArr As Variant, cell As Range)
    cell = Join(myArr, ",")
End Sub
Sub PrintArrayAsRange(myArr As Variant, cell As Range)
    cell.Resize(UBound(myArr, 1), UBound(myArr, 2)) = myArr
End Sub
Sub TestPrintArrayIntoSheet()  '2dArrayToSheet
    Dim arr As Variant
    arr = Split("a  b  c", "  ")

    'Printing in ONE-CELL: To print all array-elements as a single string separated by comma (a,b,c):
    PrintArrayIn1Cell arr, [A1]

    'Printing in SEPARATE-CELLS: To print array-elements in separate cells:
    Dim arr2D As Variant
    arr2D = Application.WorksheetFunction.Transpose(arr) 'convert a 1D array into 2D array
    PrintArrayAsRange arr2D, Range("B1:B3")
End Sub

Note: Transpose will render column-by-column output, to get row-by-row output transpose it again - hope that makes sense.


cURL error 60: SSL certificate: unable to get local issuer certificate

Attention Wamp/Wordpress/windows users. I had this issue for hours and not even the correct answer was doing it for me, because i was editing the wrong php.ini file because the question was answered to XAMPP and not for WAMP users, even though the question was for WAMP.

here's what i did

Download the certificate bundle.

Put it inside of C:\wamp64\bin\php\your php version\extras\ssl

Make sure the file is inside of C:\wamp64\bin\apache\apache(version)\modules

Enable mod_ssl in httpd.conf inside of Apache directory C:\wamp64\bin\apache\apache2.4.27\conf

Enable php_openssl.dll in php.ini. Be aware my problem was that I had two php.ini files and I need to do this in both of them. First one can be located inside of your WAMP taskbar icon here.

enter image description here

and the other one is located in C:\wamp64\bin\php\php(Version)

find the location for both of the php.ini files and find the line curl.cainfo = and give it a path like this

curl.cainfo = "C:\wamp64\bin\php\php(Version)\extras\ssl\cacert.pem"

Now save the files and restart your server and you should be good to go

Is it possible to program Android to act as physical USB keyboard?

I've modified kernel on Nexus 7 to act like standard HID keyboard and mouse, without losing MTP/ADB/other USB functionality.

You can use usb-gadget-test commandline utility to send keystrokes and mouse movements to your PC. I want to create a remote admin app later, which will send key events and receive video from camera.

Kernel patch, binaries and instructions:

Edit: I've published a proper app to Google Play, if your Nexus 7 is rooted you can flash kernel right from the app, and send keypresses with it.

Proper usage of Java -D command-line parameters

That should be:

java -Dtest="true" -jar myApplication.jar

Then the following will return the value:


The value could be null, though, so guard against an exception using a Boolean:

boolean b = Boolean.parseBoolean( System.getProperty( "test" ) );

Note that the getBoolean method delegates the system property value, simplifying the code to:

if( Boolean.getBoolean( "test" ) ) {
   // ...

Row count with PDO

This is an old post, but getting frustrated looking for alternatives. It is super unfortunate that PDO lacks this feature, especially as PHP and MySQL tend to go hand in hand.

There is an unfortunate flaw in using fetchColumn() as you can no longer use that result set (effectively) as the fetchColumn() moves the needle to the next row. So for example, if you have a result similar to

  1. Fruit->Banana
  2. Fruit->Apple
  3. Fruit->Orange

If you use fetchColumn() you can find out that there are 3 fruits returned, but if you now loop through the result, you only have two columns, The price of fetchColumn() is the loss of the first column of results just to find out how many rows were returned. That leads to sloppy coding, and totally error ridden results if implemented.

So now, using fetchColumn() you have to implement and entirely new call and MySQL query just to get a fresh working result set. (which hopefully hasn't changed since your last query), I know, unlikely, but it can happen. Also, the overhead of dual queries on all row count validation. Which for this example is small, but parsing 2 million rows on a joined query, not a pleasant price to pay.

I love PHP and support everyone involved in its development as well as the community at large using PHP on a daily basis, but really hope this is addressed in future releases. This is 'really' my only complaint with PHP PDO, which otherwise is a great class.

What is a C++ delegate?

An option for delegates in C++ that is not otherwise mentioned here is to do it C style using a function ptr and a context argument. This is probably the same pattern that many asking this question are trying to avoid. But, the pattern is portable, efficient, and is usable in embedded and kernel code.

class SomeClass
    in someMember;
    int SomeFunc( int);

    static void EventFunc( void* this__, int a, int b, int c)
        SomeClass* this_ = static_cast< SomeClass*>( this__);

        this_->SomeFunc( a );
        this_->someMember = b + c;

void ScheduleEvent( void (*delegateFunc)( void*, int, int, int), void* delegateContext);

    SomeClass* someObject = new SomeObject();
    ScheduleEvent( SomeClass::EventFunc, someObject);

When do you use varargs in Java?

Varargs are useful for any method that needs to deal with an indeterminate number of objects. One good example is String.format. The format string can accept any number of parameters, so you need a mechanism to pass in any number of objects.

String.format("This is an integer: %d", myInt);
String.format("This is an integer: %d and a string: %s", myInt, myString);

How to convert string to binary?

We just need to encode it.


How to get box-shadow on left & right sides only

clip-path is now (2020) the best way I have found to achieve box-shadows on specific sides of elements, especially when the required effect is a "clean cut" shadow at particular edges, like this:

.shadow-element {
    width: 100px;
    height: 100px;
    background-color: #FFC300;
    box-shadow: 0 0 10px 5px rgba(0,0,0,0.75);
    clip-path: inset(0px -15px 0px -15px);

    /* position and left properties required to bring element out from edge of parent
    so that shadow can be seen; margin-left would also achieve the same thing */
    position: relative;
    left: 15px;
<div class="shadow-element"></div>
_x000D_ opposed to an attenuated/reduced/thinning shadow like this:

.shadow-element {
    width: 100px;
    height: 100px;
    background-color: #FFC300;
    box-shadow: 15px 0 15px -10px rgba(0,0,0,0.75), -15px 0 15px -10px rgba(0,0,0,0.75);

    /* position and left properties required to bring element out from edge of parent
    so that shadow can be seen; margin-left would also achieve the same thing */
    position: relative;
    left: 15px;
<div class="shadow-element"></div>

Simply apply the following CSS to the element in question:

box-shadow: 0 0 Xpx Ypx [hex/rgba]; /* note 0 offset values */
clip-path: inset(Apx Bpx Cpx Dpx);


  • Apx sets the shadow visibility for the top edge
  • Bpx right
  • Cpx bottom
  • Dpx left

Enter a value of 0 for any edges where the shadow should be hidden and a negative value (the same as the combined result of the blur radius + spread values - Xpx + Ypx) to any edges where the shadow should be displayed.

Initializing a list to a known number of elements in Python

You could do this:

verts = list(xrange(1000))

That would give you a list of 1000 elements in size and which happens to be initialised with values from 0-999. As list does a __len__ first to size the new list it should be fairly efficient.

Peak-finding algorithm for Python/SciPy

For those not sure about which peak-finding algorithms to use in Python, here a rapid overview of the alternatives:

Wanting myself an equivalent to the MatLab findpeaks function, I've found that the detect_peaks function from Marcos Duarte is a good catch.

Pretty easy to use:

import numpy as np
from vector import vector, plot_peaks
from libs import detect_peaks
print('Detect peaks with minimum height and distance filters.')
indexes = detect_peaks.detect_peaks(vector, mph=7, mpd=2)
print('Peaks are: %s' % (indexes))

Which will give you:

detect_peaks results

Use jQuery to change an HTML tag?

I came up with an approach where you use a string representation of your jQuery object and replace the tag name using regular expressions and basic JavaScript. You will not loose any content and don't have to loop over each attribute/property.

 * replaceTag
 * @return {$object} a new object with replaced opening and closing tag
function replaceTag($element, newTagName) {

  // Identify opening and closing tag
  var oldTagName = $element[0].nodeName,
    elementString = $element[0].outerHTML,
    openingRegex = new RegExp("^(<" + oldTagName + " )", "i"),
    openingTag = elementString.match(openingRegex),
    closingRegex = new RegExp("(<\/" + oldTagName + ">)$", "i"),
    closingTag = elementString.match(closingRegex);

  if (openingTag && closingTag && newTagName) {
    // Remove opening tag
    elementString = elementString.slice(openingTag[0].length);
    // Remove closing tag
    elementString = elementString.slice(0, -(closingTag[0].length));
    // Add new tags
    elementString = "<" + newTagName + " " + elementString + "</" + newTagName + ">";

  return $(elementString);

Finally, you can replace the existing object/node as follows:

var $newElement = replaceTag($rankingSubmit, 'a');

Spring Boot JPA - configuring auto reconnect

Setting spring.datasource.tomcat.testOnBorrow=true in didn't work.

Programmatically setting like below worked without any issues.

import org.apache.tomcat.jdbc.pool.DataSource;
import org.apache.tomcat.jdbc.pool.PoolProperties;    

public DataSource dataSource() {
    PoolProperties poolProperties = new PoolProperties();

    //here it is
    poolProperties.setValidationQuery("SELECT 1");

    return new DataSource(poolProperties);

Creating for loop until list.length

You could learn about Python loops here:

You have to know that Python doesn't have { and } for start and end of loop, instead it depends on tab chars you enter in first of line, I mean line indents.

So you can do loop inside loop with double tab (indent)

An example of double loop is like this:

onetoten = range(1,11)
tentotwenty = range(10,21)
for count in onetoten:
    for count2 in tentotwenty

How to display div after click the button in Javascript?

HTML Code:

<div id="welcomeDiv"  style="display:none;" class="answer_list" > WELCOME</div>
<input type="button" name="answer" value="Show Div" onclick="showDiv()" />


function showDiv() {
   document.getElementById('welcomeDiv').style.display = "block";

See the Demo:

How to show disable HTML select option in by default?

I know you ask how to disable the option, but I figure the end users visual outcome is the same with this solution, although it is probably marginally less resource demanding.

Use the optgroup tag, like so :

<select name="tagging">
    <optgroup label="Choose Tagging">
        <option value="Option A">Option A</option>
        <option value="Option B">Option B</option>
        <option value="Option C">Option C</option>

Why is January month 0 in Java Calendar?

It's just part of the horrendous mess which is the Java date/time API. Listing what's wrong with it would take a very long time (and I'm sure I don't know half of the problems). Admittedly working with dates and times is tricky, but aaargh anyway.

Do yourself a favour and use Joda Time instead, or possibly JSR-310.

EDIT: As for the reasons why - as noted in other answers, it could well be due to old C APIs, or just a general feeling of starting everything from 0... except that days start with 1, of course. I doubt whether anyone outside the original implementation team could really state reasons - but again, I'd urge readers not to worry so much about why bad decisions were taken, as to look at the whole gamut of nastiness in java.util.Calendar and find something better.

One point which is in favour of using 0-based indexes is that it makes things like "arrays of names" easier:

// I "know" there are 12 months
String[] monthNames = new String[12]; // and populate...
String name = monthNames[calendar.get(Calendar.MONTH)];

Of course, this fails as soon as you get a calendar with 13 months... but at least the size specified is the number of months you expect.

This isn't a good reason, but it's a reason...

EDIT: As a comment sort of requests some ideas about what I think is wrong with Date/Calendar:

  • Surprising bases (1900 as the year base in Date, admittedly for deprecated constructors; 0 as the month base in both)
  • Mutability - using immutable types makes it much simpler to work with what are really effectively values
  • An insufficient set of types: it's nice to have Date and Calendar as different things, but the separation of "local" vs "zoned" values is missing, as is date/time vs date vs time
  • An API which leads to ugly code with magic constants, instead of clearly named methods
  • An API which is very hard to reason about - all the business about when things are recomputed etc
  • The use of parameterless constructors to default to "now", which leads to hard-to-test code
  • The Date.toString() implementation which always uses the system local time zone (that's confused many Stack Overflow users before now)

Select rows from a data frame based on values in a vector

Another option would be to use a keyed data.table:

setDT(dt, key = 'fct')[J(vc)]  # or: setDT(dt, key = 'fct')[.(vc)]

which results in:

   fct X
1:   a 2
2:   a 7
3:   a 1
4:   c 3
5:   c 5
6:   c 9
7:   c 2
8:   c 4

What this does:

  • setDT(dt, key = 'fct') transforms the data.frame to a data.table (which is an enhanced form of a data.frame) with the fct column set as key.
  • Next you can just subset with the vc vector with [J(vc)].

NOTE: when the key is a factor/character variable, you can also use setDT(dt, key = 'fct')[vc] but that won't work when vc is a numeric vector. When vc is a numeric vector and is not wrapped in J() or .(), vc will work as a rowindex.

A more detailed explanation of the concept of keys and subsetting can be found in the vignette Keys and fast binary search based subset.

An alternative as suggested by @Frank in the comments:

setDT(dt)[J(vc), on=.(fct)]

When vc contains values that are not present in dt, you'll need to add nomatch = 0:

setDT(dt, key = 'fct')[J(vc), nomatch = 0]


setDT(dt)[J(vc), on=.(fct), nomatch = 0]

Loop through files in a folder using VBA?

Here's my interpretation as a Function Instead:

'# LoopThroughFiles
'# Function to Loop through files in current directory and return filenames
'# Usage: LoopThroughFiles ActiveWorkbook.Path, "txt" 'inputDirectoryToScanForFile
Function LoopThroughFiles(inputDirectoryToScanForFile, filenameCriteria) As String

    Dim StrFile As String
    'Debug.Print "in LoopThroughFiles. inputDirectoryToScanForFile: ", inputDirectoryToScanForFile

    StrFile = Dir(inputDirectoryToScanForFile & "\*" & filenameCriteria)
    Do While Len(StrFile) > 0
        Debug.Print StrFile
        StrFile = Dir


End Function

Store an array in HashMap

If you want to store multiple values for a key (if I understand you correctly), you could try a MultiHashMap (available in various libraries, not only commons-collections).

Custom height Bootstrap's navbar

I believe you are using Bootstrap 3. If so, please try this code, here is the bootply

    <div class="navbar navbar-static-top navbar-default">
        <div class="navbar-header">
            <a class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
                <span class="glyphicon glyphicon-th-list"></span>
        <div class="container" style="background:yellow;">
            <a href="/">
                <img src="img/logo.png" class="logo img-responsive">

            <nav class="navbar-collapse collapse pull-right" style="line-height:150px; height:150px;">
                <ul class="nav navbar-nav" style="display:inline-block;">
                    <li><a href="">Portfolio</a></li>
                    <li><a href="">Blog</a></li>
                    <li><a href="">Contact</a></li>

Add context path to Spring Boot application

We can set it in the as API_CONTEXT_ROOT=/therootpath

And we access it in the Java class as mentioned below

private String contextRoot;

How to force Eclipse to ask for default workspace?

I had the same problem with indigo on linux 3.0 X86_64: After runnning eclipse -clean everything went back to normal.

Thanks to some comment on the eclipse issue:

What causes the Broken Pipe Error?

We had the Broken Pipe error after a new network was put into place. After ensuring that port 9100 was open and could connect to the printer over telnet port 9100, we changed the printer driver from "HP" to "Generic PDF", the broken pipe error went away and were able to print successfully.

(RHEL 7, Printers were Ricoh brand, the HP configuration was pre-existing and functional on the previous network)

SASS :not selector

I tried re-creating this, and .someclass.notip was being generated for me but .someclass:not(.notip) was not, for as long as I did not have the @mixin tip() defined. Once I had that, it all worked.

$dropdown-width: 100px;
$comp-tip: true;

@mixin tip($pos:right) {


@mixin dropdown-pos($pos:right) {
  &:not(.notip) {
    @if $comp-tip == true{
      @if $pos == right {
        top:$dropdown-width * -0.6;
        background-color: #f00;
        @include tip($pos:$pos);
  &.notip {
    @if $pos == right {
      top: 0;
      left:$dropdown-width * 0.8;
      background-color: #00f;

.someclass { @include dropdown-pos(); }

EDIT: is a good place to debug your SASS because it gives you error messages. Undefined mixin 'tip'. it what I get when I remove @mixin tip($pos:right) { }

How do I verify that a string only contains letters, numbers, underscores and dashes?

As an alternative to using regex you could do it in Sets:

from sets import Set

allowed_chars = Set('0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-')

if Set(my_little_sting).issubset(allowed_chars):
    # your action
    print True

How do I use Ruby for shell scripting?

This might also be helpful:

I haven't used it much, but looks pretty cool

From the site:

rush is a replacement for the unix shell (bash, zsh, etc) which uses pure Ruby syntax. Grep through files, find and kill processes, copy files - everything you do in the shell, now in Ruby

TSQL How do you output PRINT in a user defined function?

Use extended procedure xp_cmdshell to run a shell command. I used it to print output to a file:

exec xp_cmdshell 'echo "mytextoutput" >> c:\debuginfo.txt'

This creates the file debuginfo.txt if it does not exist. Then it adds the text "mytextoutput" (without quotation marks) to the file. Any call to the function will write an additional line.

You may need to enable this db-server property first (default = disabled), which I realize may not be to the liking of dba's for production environments though.

Using wire or reg with input or output in Verilog

The Verilog code compiler you use will dictate what you have to do. If you use illegal syntax, you will get a compile error.

An output must also be declared as a reg only if it is assigned using a "procedural assignment". For example:

output reg a;
always @* a = b;

There is no need to declare an output as a wire.

There is no need to declare an input as a wire or reg.

How to use paths in tsconfig.json?

Solution for 2021.

Note: CRA. Initially the idea of ??using a third party library or ejecting app for alias seemed crazy to me. However, after 8 hours of searching (and trying variant with eject), it turned out that this option is the least painful.

Step 1.

yarn add --dev react-app-rewired react-app-rewire-alias

Step 2. Create config-overrides.js file in your project's root and fill it with :

const {alias} = require('react-app-rewire-alias')

module.exports = function override(config) {
  return alias({
    assets: './src/assets',
    '@components': './src/components',

Step 3. Fix your package.json file:

  "scripts": {
-   "start": "react-scripts start",
+   "start": "react-app-rewired start",
-   "build": "react-scripts build",
+   "build": "react-app-rewired build",
-   "test": "react-scripts test",
+   "test": "react-app-rewired test",
    "eject": "react-scripts eject"

If @declarations don't work, add them to the d.ts file. For example: '@constants': './src/constants', => add in react-app-env.d.ts declare module '@constants';

That is all. Now you can continue to use yarn or npm start/build/test commands as usual.

Full version in docs.

Note: The 'Using with ts / js config' part in docs did not work for me. The error "aliased imports are not supported" when building the project remained. So I used an easier way. Luckily it works.

How do I compile a .c file on my Mac?

You'll need to get a compiler. The easiest way is probably to install XCode development environment from the CDs/DVDs you got with your Mac, which will give you gcc. Then you should be able compile it like

gcc -o mybinaryfile mysourcefile.c

hide div tag on mobile view only?

You can be guided by this example. On your css file:

.deskContent {
    background-image: url(../img/big-pic.png);
    width: 100%;
    height: 400px;
    background-repeat: no-repeat;
    background-size: contain; 

.phoneContent {
    background-image: url(../img/small-pic.png);
    width: 100%;
    height: 100px;
    background-repeat: no-repeat;
    background-size: contain;

@media all and (max-width: 959px) {
    .deskContent {display:block;}
    .phoneContent {display:none;}

@media all and (max-width: 479px) {
    .deskContent {display:none;}
    .phoneContent {display:block;}

On your html file:

<div class="deskContent">Content for desktop</div>
<div class="phoneContent">Content for mobile</div>

Error: fix the version conflict (google-services plugin)

Important Update

Both Firebase & Play-service dependencies are having independent versions unlike past. If you have version conflicts then you can update your and start defining independent version.

Step(1): Update

Open project level build.gradle and update to version 4.1.0 MUST CHECK newer if available.

buildscript {
    dependencies {
        classpath ''
        classpath '' //< update this 

Step(2): Update Firebase dependencies Latest Versions

Firebase dependency versions can be individual.    //Analytics, check latest too    //Realtime Database, check latest too

Step(3): Update Play Services dependencies Latest Versions

Play services versions also can have individual versions. //Ads, check latest too   //Analytics, check latest too

Still having issue? You can check which dependency is making conflict by reading this answer.

How do I determine whether my calculation of pi is accurate?

The Taylor series is one way to approximate pi. As noted it converges slowly.

The partial sums of the Taylor series can be shown to be within some multiplier of the next term away from the true value of pi.

Other means of approximating pi have similar ways to calculate the max error.

We know this because we can prove it mathematically.

Unable to compile class for JSP

org.apache.jasper.JasperException: Unable to compile class for JSP:

enter image

Convert generic list to dataset in C#

Have you tried binding the list to the datagridview directly? If not, try that first because it will save you lots of pain. If you have tried it already, please tell us what went wrong so we can better advise you. Data binding gives you different behaviour depending on what interfaces your data object implements. For example, if your data object only implements IEnumerable (e.g. List), you will get very basic one-way binding, but if it implements IBindingList as well (e.g. BindingList, DataView), then you get two-way binding.

How does lock work exactly?

Its simpler than you think.

According to Microsoft: The lock keyword ensures that one thread does not enter a critical section of code while another thread is in the critical section. If another thread tries to enter a locked code, it will wait, block, until the object is released.

The lock keyword calls Enter at the start of the block and Exit at the end of the block. lock keyword actually handles Monitor class at back end.

For example:

private static readonly Object obj = new Object();

lock (obj)
    // critical section

In the above code, first the thread enters a critical section, and then it will lock obj. When another thread tries to enter, it will also try to lock obj, which is already locked by the first thread. Second thread will have to wait for the first thread to release obj. When the first thread leaves, then another thread will lock obj and will enter the critical section.

Forcing anti-aliasing using css: Is this a myth?

Using an opacity setting of 99% (through the DXTransform filters) actually forces Internet Explorer to turn off ClearType, at least in Version 7. Source

How do I make a list of data frames?

If you have a large number of sequentially named data frames you can create a list of the desired subset of data frames like this:

d1 <- data.frame(y1=c(1,2,3), y2=c(4,5,6))
d2 <- data.frame(y1=c(3,2,1), y2=c(6,5,4))
d3 <- data.frame(y1=c(6,5,4), y2=c(3,2,1))
d4 <- data.frame(y1=c(9,9,9), y2=c(8,8,8))

my.list <- list(d1, d2, d3, d4)

my.list2 <- lapply(paste('d', seq(2,4,1), sep=''), get)

where my.list2 returns a list containing the 2nd, 3rd and 4th data frames.

  y1 y2
1  3  6
2  2  5
3  1  4

  y1 y2
1  6  3
2  5  2
3  4  1

  y1 y2
1  9  8
2  9  8
3  9  8

Note, however, that the data frames in the above list are no longer named. If you want to create a list containing a subset of data frames and want to preserve their names you can try this:

list.function <-  function() { 

     d1 <- data.frame(y1=c(1,2,3), y2=c(4,5,6))
     d2 <- data.frame(y1=c(3,2,1), y2=c(6,5,4))
     d3 <- data.frame(y1=c(6,5,4), y2=c(3,2,1))
     d4 <- data.frame(y1=c(9,9,9), y2=c(8,8,8))

     sapply(paste('d', seq(2,4,1), sep=''), get, environment(), simplify = FALSE) 

my.list3 <- list.function()

which returns:

> my.list3
  y1 y2
1  3  6
2  2  5
3  1  4

  y1 y2
1  6  3
2  5  2
3  4  1

  y1 y2
1  9  8
2  9  8
3  9  8

> str(my.list3)
List of 3
 $ d2:'data.frame':     3 obs. of  2 variables:
  ..$ y1: num [1:3] 3 2 1
  ..$ y2: num [1:3] 6 5 4
 $ d3:'data.frame':     3 obs. of  2 variables:
  ..$ y1: num [1:3] 6 5 4
  ..$ y2: num [1:3] 3 2 1
 $ d4:'data.frame':     3 obs. of  2 variables:
  ..$ y1: num [1:3] 9 9 9
  ..$ y2: num [1:3] 8 8 8

> my.list3[[1]]
  y1 y2
1  3  6
2  2  5
3  1  4

> my.list3$d4
  y1 y2
1  9  8
2  9  8
3  9  8

How to list all databases in the mongo shell?

Couple of commands are there to list all dbs in MongoDB shell.

first , launch Mongodb shell using 'mongo' command.


Then use any of the below commands to list all the DBs.

  • show dbs
  • show databases
  • db.adminCommand( { listDatabases: 1 , nameOnly : true} )

A snap shot

For more details please check here

Thank you.

How to construct a set out of list items in python?

You can do

my_set = set(my_list)

or, in Python 3,

my_set = {*my_list}

to create a set from a list. Conversely, you can also do

my_list = list(my_set)

or, in Python 3,

my_list = [*my_set]

to create a list from a set.

Just note that the order of the elements in a list is generally lost when converting the list to a set since a set is inherently unordered. (One exception in CPython, though, seems to be if the list consists only of non-negative integers, but I assume this is a consequence of the implementation of sets in CPython and that this behavior can vary between different Python implementations.)

Spring Boot application in eclipse, the Tomcat connector configured to listen on port XXXX failed to start

On Windows:

To get started, open the command prompt by clicking on Start and then typing cmd. In the command window, go ahead and type in the following command:

netstat -a -n -o

In the command above, the -o parameter is what will add the PID to the end of the table. Press enter and you should see something like this:

enter image description here

Now to see the name of the process that is using that port, go to Task Manager by pressing CTRL + SHIFT + ESC and then click on the Process tab. In Windows 10, you should click on the Details tab.

By default, the task manager does not display the process ID, so you have to click on View and then Select Columns.

You might also need to look into services running in background. To do that right-click and select open services as shown below:

enter image description here

Hope it helps :)

Javascript regular expression password validation having special characters

If you check the length seperately, you can do the following:

var regularExpression  = /^[a-zA-Z]$/;

if (regularExpression.test(newPassword)) {
    alert("password should contain atleast one number and one special character");
    return false;

What is an OS kernel ? How does it differ from an operating system?

In computing, the 'kernel' is the central component of most computer operating systems; it is a bridge between applications and the actual data processing done at the hardware level. The kernel's responsibilities include managing the system's resources (the communication between hardware and software components). Usually as a basic component of an operating system, a kernel can provide the lowest-level abstraction layer for the resources (especially processors and I/O devices) that application software must control to perform its function. It typically makes these facilities available to application processes through inter-process communication mechanisms and system calls.

why is plotting with Matplotlib so slow?

This may not apply to many of you, but I'm usually operating my computers under Linux, so by default I save my matplotlib plots as PNG and SVG. This works fine under Linux but is unbearably slow on my Windows 7 installations [MiKTeX under Python(x,y) or Anaconda], so I've taken to adding this code, and things work fine over there again:

import platform     # Don't save as SVG if running under Windows.
# Plot code goes here.
fig.savefig('figure_name.png', dpi = 200)
if platform.system() != 'Windows':
    # In my installations of Windows 7, it takes an inordinate amount of time to save
    # graphs as .svg files, so on that platform I've disabled the call that does so.
    # The first run of a script is still a little slow while everything is loaded in,
    # but execution times of subsequent runs are improved immensely.

Use of Finalize/Dispose method in C#

Note that any IDisposable implementation should follow the below pattern (IMHO). I developed this pattern based on info from several excellent .NET "gods" the .NET Framework Design Guidelines (note that MSDN does not follow this for some reason!). The .NET Framework Design Guidelines were written by Krzysztof Cwalina (CLR Architect at the time) and Brad Abrams (I believe the CLR Program Manager at the time) and Bill Wagner ([Effective C#] and [More Effective C#] (just take a look for these on

Note that you should NEVER implement a Finalizer unless your class directly contains (not inherits) UNmanaged resources. Once you implement a Finalizer in a class, even if it is never called, it is guaranteed to live for an extra collection. It is automatically placed on the Finalization Queue (which runs on a single thread). Also, one very important note...all code executed within a Finalizer (should you need to implement one) MUST be thread-safe AND exception-safe! BAD things will happen otherwise...(i.e. undetermined behavior and in the case of an exception, a fatal unrecoverable application crash).

The pattern I've put together (and written a code snippet for) follows:

#region IDisposable implementation

//TODO remember to make this class inherit from IDisposable -> $className$ : IDisposable

// Default initialization for a bool is 'false'
private bool IsDisposed { get; set; }

/// <summary>
/// Implementation of Dispose according to .NET Framework Design Guidelines.
/// </summary>
/// <remarks>Do not make this method virtual.
/// A derived class should not be able to override this method.
/// </remarks>
public void Dispose()
    Dispose( true );

    // This object will be cleaned up by the Dispose method.
    // Therefore, you should call GC.SupressFinalize to
    // take this object off the finalization queue 
    // and prevent finalization code for this object
    // from executing a second time.

    // Always use SuppressFinalize() in case a subclass
    // of this type implements a finalizer.
    GC.SuppressFinalize( this );

/// <summary>
/// Overloaded Implementation of Dispose.
/// </summary>
/// <param name="isDisposing"></param>
/// <remarks>
/// <para><list type="bulleted">Dispose(bool isDisposing) executes in two distinct scenarios.
/// <item>If <paramref name="isDisposing"/> equals true, the method has been called directly
/// or indirectly by a user's code. Managed and unmanaged resources
/// can be disposed.</item>
/// <item>If <paramref name="isDisposing"/> equals false, the method has been called by the 
/// runtime from inside the finalizer and you should not reference 
/// other objects. Only unmanaged resources can be disposed.</item></list></para>
/// </remarks>
protected virtual void Dispose( bool isDisposing )
    // TODO If you need thread safety, use a lock around these 
    // operations, as well as in your methods that use the resource.
        if( !this.IsDisposed )
            if( isDisposing )
                // TODO Release all managed resources here


            // TODO Release all unmanaged resources here

            // TODO explicitly set root references to null to expressly tell the GarbageCollector
            // that the resources have been disposed of and its ok to release the memory allocated for them.

        // explicitly call the base class Dispose implementation
        base.Dispose( isDisposing );

        this.IsDisposed = true;

//TODO Uncomment this code if this class will contain members which are UNmanaged
///// <summary>Finalizer for $className$</summary>
///// <remarks>This finalizer will run only if the Dispose method does not get called.
///// It gives your base class the opportunity to finalize.
///// DO NOT provide finalizers in types derived from this class.
///// All code executed within a Finalizer MUST be thread-safe!</remarks>
//  ~$className$()
//  {
//     Dispose( false );
//  }
#endregion IDisposable implementation

Here is the code for implementing IDisposable in a derived class. Note that you do not need to explicitly list inheritance from IDisposable in the definition of the derived class.

public DerivedClass : BaseClass, IDisposable (remove the IDisposable because it is inherited from BaseClass)

protected override void Dispose( bool isDisposing )
        if ( !this.IsDisposed )
            if ( isDisposing )
                // Release all managed resources here

        // explicitly call the base class Dispose implementation
        base.Dispose( isDisposing );

I've posted this implementation on my blog at: How to Properly Implement the Dispose Pattern

How to delete an element from an array in C#

You can also convert your array to a list and call remove on the list. You can then convert back to your array.

int[] numbers = {1, 3, 4, 9, 2};
var numbersList = numbers.ToList();

jQuery: click function exclude children.

I personally would add a click handler to the child element that did nothing but stop the propagation of the click. So it would look something like:

$('.example > div').click(function (e) {

import dat file into R

The dat file has some lines of extra information before the actual data. Skip them with the skip argument:

           header=TRUE, skip=3)

An easy way to check this if you are unfamiliar with the dataset is to first use readLines to check a few lines, as below:

# [1] "Ozone data from CZ03 2009"   "Local time: GMT + 0"        
# [3] ""                            "Date        Hour      Value"
# [5] "01.01.2009 00:00       34.3" "01.01.2009 01:00       31.9"
# [7] "01.01.2009 02:00       29.9" "01.01.2009 03:00       28.5"
# [9] "01.01.2009 04:00       32.9" "01.01.2009 05:00       20.5"

Here, we can see that the actual data starts at [4], so we know to skip the first three lines.


If you really only wanted the Value column, you could do that by:

               header=TRUE, skip=3)$Value)

Again, readLines is useful for helping us figure out the actual name of the columns we will be importing.

But I don't see much advantage to doing that over reading the whole dataset in and extracting later.

Export data from Chrome developer tool

Right-click and export as HAR, then view it using Jan Odvarko's HAR Viewer

This helps in visualising the already captured HAR logs.

How can I check for IsPostBack in JavaScript?

Try this, in this JS we can check if it is post back or not and accordingly do operations in the respective loops.

    window.onload = isPostBack;

    function isPostBack() {

        if (!document.getElementById('clientSideIsPostBack')) {
            return false;

        if (document.getElementById('clientSideIsPostBack').value == 'Y') {


            return true;
        else {


            return false;

How to obtain image size using standard Python class (without using external library)?

Regarding Fred the Fantastic's answer:

Not every JPEG marker between C0-CF are SOF markers; I excluded DHT (C4), DNL (C8) and DAC (CC). Note that I haven't looked into whether it is even possible to parse any frames other than C0 and C2 in this manner. However, the other ones seem to be fairly rare (I personally haven't encountered any other than C0 and C2).

Either way, this solves the problem mentioned in comments by Malandy with Bangles.jpg (DHT erroneously parsed as SOF).

The other problem mentioned with 1431588037-WgsI3vK.jpg is due to imghdr only being able detect the APP0 (EXIF) and APP1 (JFIF) headers.

This can be fixed by adding a more lax test to imghdr (e.g. simply FFD8 or maybe FFD8FF?) or something much more complex (possibly even data validation). With a more complex approach I've only found issues with: APP14 (FFEE) (Adobe); the first marker being DQT (FFDB); and APP2 and issues with embedded ICC_PROFILEs.

Revised code below, also altered the call to imghdr.what() slightly:

import struct
import imghdr

def test_jpeg(h, f):
    if h[0:4] == '\xff\xd8\xff\xe2' and h[6:17] == b'ICC_PROFILE':
        print "A"
        return 'jpeg'
    # SOI APP14 + Adobe
    if h[0:4] == '\xff\xd8\xff\xee' and h[6:11] == b'Adobe':
        return 'jpeg'
    # SOI DQT
    if h[0:4] == '\xff\xd8\xff\xdb':
        return 'jpeg'

def get_image_size(fname):
    '''Determine the image type of fhandle and return its size.
    from draco'''
    with open(fname, 'rb') as fhandle:
        head =
        if len(head) != 24:
        what = imghdr.what(None, head)
        if what == 'png':
            check = struct.unpack('>i', head[4:8])[0]
            if check != 0x0d0a1a0a:
            width, height = struct.unpack('>ii', head[16:24])
        elif what == 'gif':
            width, height = struct.unpack('<HH', head[6:10])
        elif what == 'jpeg':
       # Read 0xff next
                size = 2
                ftype = 0
                while not 0xc0 <= ftype <= 0xcf or ftype in (0xc4, 0xc8, 0xcc):
          , 1)
                    byte =
                    while ord(byte) == 0xff:
                        byte =
                    ftype = ord(byte)
                    size = struct.unpack('>H',[0] - 2
                # We are at a SOFn block
      , 1)  # Skip `precision' byte.
                height, width = struct.unpack('>HH',
            except Exception: #IGNORE:W0703
        return width, height

Note: Created a full answer instead of a comment, since I'm not yet allowed to.

How can I get dictionary key as variable directly in Python (not by searching from value)?

keys=[i for i in mydictionary.keys()] or keys = list(mydictionary.keys())

'python' is not recognized as an internal or external command

Option 1 : Select on add environment var during installation Option 2 : Go to C:\Users-> AppData (hidden file) -> Local\Programs\Python\Python38-32(depends on version installed)\Scripts Copy path and add to env vars path.

For me this path worked : C:\Users\Username\AppData\Local\Programs\Python\Python38-32\Scripts

DataGridView - how to set column width?

You can set default width and height for all Columns and Rows as below only with one loop.

    // DataGridView Name= dgvMachineStatus

   foreach (DataGridViewColumn column in dgvMachineStatus.Columns)
            column.Width = 155;

   foreach (DataGridViewRow row in dgvMachineStatus.Rows)
            row.Height = 45;

Removing all line breaks and adding them after certain text

You can also go to Notepad++ and do the following steps:

Edit->LineOperations-> Remove Empty Lines or Remove Empty Lines(Containing blank characters)

Why does find -exec mv {} ./target/ + not work?

no, the difference between + and \; should be reversed. + appends the files to the end of the exec command then runs the exec command and \; runs the command for each file.

The problem is find . -type f -iname '*.cpp' -exec mv {} ./test/ \+ should be find . -type f -iname '*.cpp' -exec mv {} ./test/ + no need to escape it or terminate the +

xargs I haven't used in a long time but I think works like +.

How to create a jQuery plugin with methods?

Too late but maybe it can help someone one day.

I was in the same situation like, creating a jQuery plugin with some methods, and after reading some articles and some tires I create a jQuery plugin boilerplate (

In addition, I develop with it a plugin to manage tags ( and wrote a two blog posts explaining step by step the creation of a jQuery plugin (

How to get client's IP address using JavaScript?

You can't. You'd have to ask a server.

C# Inserting Data from a form into an access Database

Password is a reserved word. Bracket that field name to avoid confusing the db engine.

INSERT into Login (Username, [Password])

What is a PDB file?

I had originally asked myself the question "Do I need a PDB file deployed to my customer's machine?", and after reading this post, decided to exclude the file.

Everything worked fine, until today, when I was trying to figure out why a message box containing an Exception.StackTrace was missing the file and line number information - necessary for troubleshooting the exception. I re-read this post and found the key nugget of information: that although the PDB is not necessary for the app to run, it is necessary for the file and line numbers to be present in the StackTrace string. I included the PDB file in the executable folder and now all is fine.

CURL to pass SSL certifcate and password

I went through this when trying to get a clientcert and private key out of a keystore.

The link above posted by welsh was great, but there was an extra step on my redhat distribution. If curl is built with NSS ( run curl --version to see if you see NSS listed) then you need to import the keys into an NSS keystore. I went through a bunch of convoluted steps, so this may not be the cleanest way, but it got things working

So export the keys into .p12

keytool -importkeystore -srckeystore $jksfile -destkeystore $p12file \
        -srcstoretype JKS -deststoretype PKCS12 \
        -srcstorepass $jkspassword -deststorepass $p12password  
        -srcalias $myalias -destalias $myalias \
        -srckeypass $keypass -destkeypass $keypass -noprompt

And generate the pem file that holds only the key

 echo making ${fileroot}.key.pem
 openssl pkcs12 -in $p12 -out ${fileroot}.key.pem  \
         -passin pass:$p12password  \
         -passout pass:$p12password  -nocerts
  • Make an empty keystore:
mkdir ~/nss
chmod 700 ~/nss
certutil -N -d ~/nss
  • Import the keys into the keystore
pks12util -i <mykeys>.p12 -d ~/nss -W <password for cert >

Now curl should work.

curl --insecure --cert <client cert alias>:<password for cert> \
     --key ${fileroot}.key.pem  <URL>

As I mentioned, there may be other ways to do this, but at least this was repeatable for me. If curl is compiled with NSS support, I was not able to get it to pull the client cert from a file.

Is it possible to force row level locking in SQL Server?

You can use the ROWLOCK hint, but AFAIK SQL may decide to escalate it if it runs low on resources

From the doco:

ROWLOCK Specifies that row locks are taken when page or table locks are ordinarily taken. When specified in transactions operating at the SNAPSHOT isolation level, row locks are not taken unless ROWLOCK is combined with other table hints that require locks, such as UPDLOCK and HOLDLOCK.


Lock hints ROWLOCK, UPDLOCK, AND XLOCK that acquire row-level locks may place locks on index keys rather than the actual data rows. For example, if a table has a nonclustered index, and a SELECT statement using a lock hint is handled by a covering index, a lock is acquired on the index key in the covering index rather than on the data row in the base table.

And finally this gives a pretty in-depth explanation about lock escalation in SQL Server 2005 which was changed in SQL Server 2008.

There is also, the very in depth: Locking in The Database Engine (in books online)

So, in general

Employees WITH (ROWLOCK)
SET Name='Mr Bean'
WHERE Age>93

Should be ok, but depending on the indexes and load on the server it may end up escalating to a page lock.

iconv - Detected an illegal character in input string

I found one Solution :

echo iconv('UTF-8', 'ASCII//TRANSLIT', utf8_encode($string));

use utf8_encode()

bad operand types for binary operator "&" java

Because & has a lesser priority than ==.

Your code is equivalent to a[0] & (1 == 0), and unless a[0] is a boolean this won't compile...

You need to:

(a[0] & 1) == 0

etc etc.

(yes, Java does hava a boolean & operator -- a non shortcut logical and)

How do I clear my Jenkins/Hudson build history?

Go to the %HUDSON_HOME%\jobs\<projectname> remove builds dir and remove lastStable, lastSuccessful links, and remove nextBuildNumber file.

After doing above steps go to below link from UI
Jenkins-> Manage Jenkins -> Reload Configuration from Disk

It will do as you need

StringIO in Python3

You can use the StringIO from the six module:

import six
import numpy

x = "1 3\n 4.5 8"

Condition within JOIN or WHERE

For inner joins I have not really noticed a difference (but as with all performance tuning, you need to check against your database under your conditions).

However where you put the condition makes a huge difference if you are using left or right joins. For instance consider these two queries:

FROM dbo.Customers AS CUS 
LEFT JOIN dbo.Orders AS ORD 
ON CUS.CustomerID = ORD.CustomerID
WHERE ORD.OrderDate >'20090515'

FROM dbo.Customers AS CUS 
LEFT JOIN dbo.Orders AS ORD 
ON CUS.CustomerID = ORD.CustomerID
AND ORD.OrderDate >'20090515'

The first will give you only those records that have an order dated later than May 15, 2009 thus converting the left join to an inner join.

The second will give those records plus any customers with no orders. The results set is very different depending on where you put the condition. (Select * is for example purposes only, of course you should not use this in production code.)

The exception to this is when you want to see only the records in one table but not the other. Then you use the where clause for the condition not the join.

FROM dbo.Customers AS CUS 
LEFT JOIN dbo.Orders AS ORD 
ON CUS.CustomerID = ORD.CustomerID
WHERE ORD.OrderID is null

How to add hamburger menu in bootstrap

All you have to do is read the code on


<script src=""></script>_x000D_
<script src=""></script>_x000D_
<link rel="stylesheet" href="">_x000D_
<nav class="navbar navbar-inverse navbar-static-top" role="navigation">_x000D_
  <div class="container">_x000D_
    <div class="navbar-header">_x000D_
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">_x000D_
                    <span class="sr-only">Toggle navigation</span>_x000D_
                    <span class="icon-bar"></span>_x000D_
                    <span class="icon-bar"></span>_x000D_
                    <span class="icon-bar"></span>_x000D_
    <!-- Collect the nav links, forms, and other content for toggling -->_x000D_
    <div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">_x000D_
      <ul class="nav navbar-nav">_x000D_
        <li><a href="index.php">Home</a></li>_x000D_
        <li><a href="about.php">About</a></li>_x000D_
        <li><a href="#portfolio">Portfolio</a></li>_x000D_
        <li><a href="#">Blog</a></li>_x000D_
        <li><a href="contact.php">Contact</a></li>_x000D_

How to save a figure in MATLAB from the command line?

If you want to save it as .fig file, hgsave is the function in Matlab R2012a. In later versions, savefig may also work.

jQuery add image inside of div tag

If we want to change the content of <div> tag whenever the function image()is called, we have to do like this:


function image() {
    var img = document.createElement("IMG");
    img.src = "/images/img1.gif";


<div id="image"></div>
<div><a href="javascript:image();">First Image</a></div>

How can I modify a saved Microsoft Access 2007 or 2010 Import Specification?

Below are three functions you can use to alter and use the MS Access 2010 Import Specification. The third sub changes the name of an existing import specification. The second sub allows you to change any xml text in the import spec. This is useful if you need to change column names, data types, add columns, change the import file location, etc.. In essence anything you want modify for an existing spec. The first Sub is a routine that allows you to call an existing import spec, modify it for a specific file you are attempting to import, importing that file, and then deleting the modified spec, keeping the import spec "template" unaltered and intact. Enjoy.

Public Sub MyExcelTransfer(myTempTable As String, myPath As String)
On Error GoTo ERR_Handler:
    Dim mySpec As ImportExportSpecification
    Dim myNewSpec As ImportExportSpecification
    Dim x As Integer

    For x = 0 To CurrentProject.ImportExportSpecifications.Count - 1
    If CurrentProject.ImportExportSpecifications.Item(x).Name = "TemporaryImport" Then
        x = CurrentProject.ImportExportSpecifications.Count
    End If
    Next x
    Set mySpec = CurrentProject.ImportExportSpecifications.Item(myTempTable)
    CurrentProject.ImportExportSpecifications.Add "TemporaryImport", mySpec.XML
    Set myNewSpec = CurrentProject.ImportExportSpecifications.Item("TemporaryImport")

    myNewSpec.XML = Replace(myNewSpec.XML, "\\MyComputer\ChangeThis", myPath)
    Set mySpec = Nothing
    Set myNewSpec = Nothing
    For x = 0 To CurrentProject.ImportExportSpecifications.Count - 1
    If CurrentProject.ImportExportSpecifications.Item(x).Name = "TemporaryImport" Then
        x = CurrentProject.ImportExportSpecifications.Count
    End If
    Next x
Exit Sub    
    MsgBox Err.Description
    Resume exit_ErrHandler
End Sub

Public Sub fixImportSpecs(myTable As String, strFind As String, strRepl As String)
    Dim mySpec As ImportExportSpecification    
    Set mySpec = CurrentProject.ImportExportSpecifications.Item(myTable)    
    mySpec.XML = Replace(mySpec.XML, strFind, strRepl)
    Set mySpec = Nothing
End Sub

Public Sub MyExcelChangeName(OldName As String, NewName As String)
    Dim mySpec As ImportExportSpecification
    Dim myNewSpec As ImportExportSpecification
    Set mySpec = CurrentProject.ImportExportSpecifications.Item(OldName)    
    CurrentProject.ImportExportSpecifications.Add NewName, mySpec.XML
    Set mySpec = Nothing
    Set myNewSpec = Nothing
End Sub

Why do people use Heroku when AWS is present? What distinguishes Heroku from AWS?

There are a lot of different ways to look at this decision from development, IT, and business objectives, so don't feel bad if it seems overwhelming. But also - don't overthink scalability.

Think about your requirements.

I've engineered websites which have serviced over 8M uniques a day and delivered terabytes of video a week built on infrastructures starting at $250k in capital hardware unr by a huge $MM IT labor staff.

But I've also had smaller websites which were designed to generate $10-$20k per year, didn't have very high traffic, db or processing requirements, and I ran those off a $10/mo generic hosting account without compromise.

In the future, deployment will look more like Heroku than AWS, just because of progress. There is zero value in the IT knob-turning of scaling internet infrastructures which isn't increasingly automatable, and none of it has anything to do with the value of the product or service you are offering.

Also, keep in mind with a commercial website - scalability is what we often call a 'good problem to have' - although scalability issues with sites like Facebook and Twitter were very high-profile, they had zero negative effect on their success - the news might have even contributed to more signups (all press is good press).

If you have a service which is generating a 100k+ uniques a day and having scaling issues, I'd be glad to take it off your hands for you no matter what the language, db, platform, or infrastructure you are running on!

Scalability is a fixable implementation problem - not having customers is an existential issue.

return value after a promise

Use a pattern along these lines:

function getValue(file) {
  return lookupValue(file);

getValue('myFile.txt').then(function(res) {
  // do whatever with res here

(although this is a bit redundant, I'm sure your actual code is more complicated)

Get value of div content using jquery

your div looks like this:

<div class="readonly_label" id="field-function_purpose">Other</div>

With jquery you can easily get inner content:

Use .html() : HTML contents of the first element in the set of matched elements or set the HTML contents of every matched element.

var text = $('#field-function_purpose').html(); 

Read more about jquery .html()


Use .text() : Get the combined text contents of each element in the set of matched elements, including their descendants, or set the text contents of the matched elements.

var text = $('#field-function_purpose').text();

Read more about jquery .text()

Suppress output of a function

It isn't clear why you want to do this without sink, but you can wrap any commands in the invisible() function and it will suppress the output. For instance:

1:10 # prints output
invisible(1:10) # hides it

Otherwise, you can always combine things into one line with a semicolon and parentheses:

{ sink("/dev/null"); ....; sink(); }

mySQL Error 1040: Too Many Connection

It is worth knowing that if you run out of usable disc space on your server partition or drive, that this will also cause MySQL to return this error. If you're sure it's not the actual number of users connected then the next step is to check that you have free space on your MySQL server drive/partition.

Edit January 2019:
This is true of MySQL 5.7 and 5.8 . I do not know for versions above this.

Difference between a SOAP message and a WSDL?

A SOAP message is a XML document which is used to transmit your data. WSDL is an XML document which describes how to connect and make requests to your web service.

Basically SOAP messages are the data you transmit, WSDL tells you what you can do and how to make the calls.

A quick search in Google will yield many sources for additional reading (previous book link now dead, to combat this will put any new recommendations in comments)

Just noting your specific questions:

Are all SOAP messages WSDL's? No, they are not the same thing at all.

Is SOAP a protocol that accepts its own 'SOAP messages' or 'WSDL's? No - reading required as this is far off.

If they are different, then when should I use SOAP messages and when should I use WSDL's? Soap is structure you apply to your message/data for transfer. WSDLs are used only to determine how to make calls to the service in the first place. Often this is a one time thing when you first add code to make a call to a particular webservice.

How do I concatenate two strings in C?

In C, you don't really have strings, as a generic first-class object. You have to manage them as arrays of characters, which mean that you have to determine how you would like to manage your arrays. One way is to normal variables, e.g. placed on the stack. Another way is to allocate them dynamically using malloc.

Once you have that sorted, you can copy the content of one array to another, to concatenate two strings using strcpy or strcat.

Having said that, C do have the concept of "string literals", which are strings known at compile time. When used, they will be a character array placed in read-only memory. It is, however, possible to concatenate two string literals by writing them next to each other, as in "foo" "bar", which will create the string literal "foobar".

How to add a response header on nginx when using proxy_pass?

As oliver writes:

add_header works as well with proxy_pass as without.

However, as Shane writes, as of Nginx 1.7.5, you must pass always in order to get add_header to work for error responses, like so:

add_header  X-Upstream  $upstream_addr always;

Check if an element is present in a Bash array

Obvious caveats aside, if your array was actually like the one above, you could do

if [[ ${arr[*]} =~ d ]]
  do your thing
  do something

Run-time error '1004' - Method 'Range' of object'_Global' failed

When you reference Range like that it's called an unqualified reference because you don't specifically say which sheet the range is on. Unqualified references are handled by the "_Global" object that determines which object you're referring to and that depends on where your code is.

If you're in a standard module, unqualified Range will refer to Activesheet. If you're in a sheet's class module, unqualified Range will refer to that sheet.

inputTemplateContent is a variable that contains a reference to a range, probably a named range. If you look at the RefersTo property of that named range, it likely points to a sheet other than the Activesheet at the time the code executes.

The best way to fix this is to avoid unqualified Range references by specifying the sheet. Like

With ThisWorkbook.Worksheets("Template")
    .Range(inputTemplateHeader).Value = NO_ENTRY
    .Range(inputTemplateContent).Value = NO_ENTRY
End With

Adjust the workbook and worksheet references to fit your particular situation.

How to do Select All(*) in linq to sql

from row in TableA select row

Or just:


In method syntax, with other operators:

TableA.Where(row => row.IsInteresting) // no .Select(), returns the whole row.

Essentially, you already are selecting all columns, the select then transforms that to the columns you care about, so you can even do things like:

from user in Users select user.LastName+", "+user.FirstName

Create folder with batch but only if it doesn't already exist

This should work for you:

IF NOT EXIST "\path\to\your\folder" md \path\to\your\folder

However, there is another method, but it may not be 100% useful:

md \path\to\your\folder >NUL 2>NUL

This one creates the folder, but does not show the error output if folder exists. I highly recommend that you use the first one. The second one is if you have problems with the other.

How to check if a socket is connected/disconnected in C#?

As Paul Turner answered Socket.Connected cannot be used in this situation. You need to poll connection every time to see if connection is still active. This is code I used:

bool SocketConnected(Socket s)
    bool part1 = s.Poll(1000, SelectMode.SelectRead);
    bool part2 = (s.Available == 0);
    if (part1 && part2)
        return false;
        return true;

It works like this:

  • s.Poll returns true if
    • connection is closed, reset, terminated or pending (meaning no active connection)
    • connection is active and there is data available for reading
  • s.Available returns number of bytes available for reading
  • if both are true:
    • there is no data available to read so connection is not active

OSError: [WinError 193] %1 is not a valid Win32 application

OSError: [WinError 193] %1 is not a valid Win32 application

This error is most probably due to this line import subprocess

I had the same issue and had solved it by uninstalling and reinstalling python and anaconda then i used jupyter and wrote pip install numpy this gave me the whole path where it was getting my site-packages from i deleted my site-packages folder and then the error dissappeared. Actually because i had 2 folders for site-packages one with anaconda and other somewhere in app data(which had some issues in it), since i deleted that site-package folder then it automatically started taking my libraries from site-package folder which was with anaconda hence the problem was solved.

Insert a new row into DataTable

You can do this, I am using

DataTable 1.10.5

using this code:

var versionNo = $.fn.dataTable.version;

This is how I insert new record on my DataTable using row.add (My table has 10 columns), which can also includes HTML tag elements:

function fncInsertNew() {
            var table = $('#tblRecord').DataTable();

                    "Tiger Nixon",
                    "System Architect",
                    "Tiger Nixon",
                    "System Architect",

For multiple inserts at the same time, use rows.add instead:

var table = $('#tblRecord').DataTable();

table.rows.add( [ {
        "Tiger Nixon",
        "System Architect",
    }, {
        "Garrett Winters",

Why does Eclipse automatically add appcompat v7 library support whenever I create a new project?

Why my eclipse automatically adds appcompat v7 library support whenever i create a new project

Because your target SDK is set to 15, in which the Action Bar is on by default and your minimum supported SDK is set to 10. Action Bar come out in 11, so you need a support library, Eclipse adds it for you. Reference.

You can configure project libraries in the build path of project properties.

Java equivalent of unsigned long long?

Java does not have unsigned types. As already mentioned, incure the overhead of BigInteger or use JNI to access native code.

Test if executable exists in Python?

See os.path module for some useful functions on pathnames. To check if an existing file is executable, use os.access(path, mode), with the os.X_OK mode.


Value to include in the mode parameter of access() to determine if path can be executed.

EDIT: The suggested which() implementations are missing one clue - using os.path.join() to build full file names.

How to print something to the console in Xcode?

You can also use breakpoints. Assuming the value you want is defined within the scope of your breakpoint you have 3 options:

print it in console doing:

po some_paramter

Bare in mind in objective-c for properties you can't use self.

po _someProperty
po self.someProperty // would not work

po stands for print object.

Or can just use Xcode 'Variable Views' . See the image enter image description here

I highly recommend seeing Debugging with Xcode from Apple

Or just hover over within your code. Like the image below.

enter image description here

How can you detect the version of a browser?

Use this:

alert(BrowserDetect.browser); // will say "Firefox"
alert(BrowserDetect.version); // will say "3" or "4"

CSS text-align: center; is not centering things

I assume you want all the items next to each other, and the whole thing to be centered horizontally.

li elements are display: block by default, taking up all the horizontal space.


div#footer ul li { display: inline }

once you've done that, you probably want to get rid of the list's bullets:

div#footer ul { list-style-type: none; padding: 0px; margin: 0px }

rbenv not changing ruby version

Check that PATH contains $HOME/.rbenv/shims and $HOME/.rbenv/bin

$ env | grep PATH

Also check that you have the following in your ~/.bash_profile if using bash or ~/.zshenv if using zsh

export PATH="$HOME/.rbenv/bin:$PATH"
eval "$(rbenv init -)"

NOTE: Make sure it's the last setting in your ~/.bash_profile . I ran into an issue where I installed a program that updated my .bash_profile and reset PATH.

Finally, make sure your $HOME folder doesn't have a .ruby-version file that you may have created by accident if you were to have done $ rbenv local <ruby-version> in your $HOME folder. Doing $ rbenv global <ruby-version> modifies the $HOME/.rbenv/version file, and the existence of a .ruby-version file in the $HOME folder would override the version set by $HOME/.rbenv/version.

From the docs:

Choosing the Ruby Version When you execute a shim, rbenv determines which Ruby version to use by reading it from the following sources, in this order:

The RBENV_VERSION environment variable, if specified. You can use the rbenv shell command to set this environment variable in your current shell session.

The first .ruby-version file found by searching the directory of the script you are executing and each of its parent directories until reaching the root of your filesystem.

The first .ruby-version file found by searching the current working directory and each of its parent directories until reaching the root of your filesystem. You can modify the .ruby-version file in the current working directory with the rbenv local command.

The global ~/.rbenv/version file. You can modify this file using the rbenv global command. If the global version file is not present, rbenv assumes you want to use the "system" Ruby—i.e. whatever version would be run if rbenv weren't in your path.

Attach the Java Source Code

The option provided by"praveenak" can also be applied to any other jar files with source file provided. For example, for JavaFx, we right click jfxrt.jar, select "Properties" and enter jdk1.8.0_05/ for "Path" under External location.

Carry Flag, Auxiliary Flag and Overflow Flag in Assembly

Carry Flag is a flag set when:

a) two unsigned numbers were added and the result is larger than "capacity" of register where it is saved. Ex: we wanna add two 8 bit numbers and save result in 8 bit register. In your example: 255 + 9 = 264 which is more that 8 bit register can store. So the value "8" will be saved there (264 & 255 = 8) and CF flag will be set.

b) two unsigned numbers were subtracted and we subtracted the bigger one from the smaller one. Ex: 1-2 will give you 255 in result and CF flag will be set.

Auxiliary Flag is used as CF but when working with BCD. So AF will be set when we have overflow or underflow on in BCD calculations. For example: considering 8 bit ALU unit, Auxiliary flag is set when there is carry from 3rd bit to 4th bit i.e. carry from lower nibble to higher nibble. (Wiki link)

Overflow Flag is used as CF but when we work on signed numbers. Ex we wanna add two 8 bit signed numbers: 127 + 2. the result is 129 but it is too much for 8bit signed number, so OF will be set. Similar when the result is too small like -128 - 1 = -129 which is out of scope for 8 bit signed numbers.

You can read more about flags on wikipedia

Right way to write JSON deserializer in Spring or extend it

I was trying to @Autowire a Spring-managed service into my Deserializer. Somebody tipped me off to Jackson using the new operator when invoking the serializers/deserializers. This meant no auto-wiring of Jackson's instance of my Deserializer. Here's how I was able to @Autowire my service class into my Deserializer:


    <bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
      <property name="objectMapper" ref="objectMapper" />
<bean id="objectMapper" class="org.springframework.http.converter.json.Jackson2ObjectMapperFactoryBean">
    <!-- Add deserializers that require autowiring -->
    <property name="deserializersByType">
        <map key-type="java.lang.Class">
            <entry key="com.acme.Anchor">
                <bean class="com.acme.AnchorDeserializer" />

Now that my Deserializer is a Spring-managed bean, auto-wiring works!

public class AnchorDeserializer extends JsonDeserializer<Anchor> {
    private AnchorService anchorService;
    public Anchor deserialize(JsonParser parser, DeserializationContext context)
             throws IOException, JsonProcessingException {
        // Do stuff

public class AnchorService {}

Update: While my original answer worked for me back when I wrote this, @xi.lin's response is exactly what is needed. Nice find!

How to do a Postgresql subquery in select clause with join in from clause like SQL Server?

I know this is old, but since Postgresql 9.3 there is an option to use a keyword "LATERAL" to use RELATED subqueries inside of JOINS, so the query from the question would look like:

    name, author_id, count(*),
    names as n1
            count(*) as total
            names as n2
            AND n2.author_id = n1.author_id
    ) as t ON 1=1
GROUP BY, n1.author_id

Add Custom Headers using HttpWebRequest

You should do ex.StackTrace instead of ex.ToString()

Spring .properties file: get element as an Array

And incase you a different delimiter other than comma, you can use that as well.

private String[] myValues;   // could also be a List<String>


in your application properties you could have

my.config.values=value1, value2, value3

How can I create an utility class?

I would make the class final and every method would be static.

So the class cannot be extended and the methods can be called by Classname.methodName. If you add members, be sure that they work thread safe ;)

How can I make a link from a <td> table cell

Use this code. It expands an <a> to fill the cell horizontally. To fill vertically, use the height property as well.

td a {_x000D_
  width: 100%;_x000D_
  display: block;_x000D_
td {_x000D_
  /* Cell styles for demonstration purposes only */_x000D_
  border: 1px solid black;_x000D_
  width: 10em;_x000D_
    <a href="">_x000D_
      Hello World_x000D_

Why aren't variable-length arrays part of the C++ standard?

There recently was a discussion about this kicked off in usenet: Why no VLAs in C++0x.

I agree with those people that seem to agree that having to create a potential large array on the stack, which usually has only little space available, isn't good. The argument is, if you know the size beforehand, you can use a static array. And if you don't know the size beforehand, you will write unsafe code.

C99 VLAs could provide a small benefit of being able to create small arrays without wasting space or calling constructors for unused elements, but they will introduce rather large changes to the type system (you need to be able to specify types depending on runtime values - this does not yet exist in current C++, except for new operator type-specifiers, but they are treated specially, so that the runtime-ness doesn't escape the scope of the new operator).

You can use std::vector, but it is not quite the same, as it uses dynamic memory, and making it use one's own stack-allocator isn't exactly easy (alignment is an issue, too). It also doesn't solve the same problem, because a vector is a resizable container, whereas VLAs are fixed-size. The C++ Dynamic Array proposal is intended to introduce a library based solution, as alternative to a language based VLA. However, it's not going to be part of C++0x, as far as I know.

Receiving JSON data back from HTTP request

Install this nuget package from Microsoft System.Net.Http.Json. It contains extension methods.

Then add using System.Net.Http.Json

Now, you'll be able to see these methods:

enter image description here

So you can now do this:

await httpClient.GetFromJsonAsync<IList<WeatherForecast>>("weatherforecast");


Make outer div be automatically the same height as its floating content

You may want to try self-closing floats, as detailed on

So perhaps try either overflow: auto (usually works), or overflow: hidden, as alex said.

How to get history on react-router v4?

In App.js

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

 const TheContext = React.createContext(null);

 const App = () => {
   const history = useHistory();

   <TheContext.Provider value={{ history, user }}>

        <Route exact path="/" render={(props) => <Home {...props} />} />
          render={(props) => <SignUp {...props} setUser={setUser} />}
        /> ...

Then in a child component :

const Welcome = () => {
    const {user, history} = React.useContext(TheContext); 

sorting integers in order lowest to highest java

import java.util.Arrays;

public class sortNumber {

public static void main(String[] args) {
    // Our array contains 13 elements 
    int[] array = {9,  238,  248,  138,  118,  45,  180,  212,  103,  230,  104,  41,  49}; 


    System.out.printf(" The result : %s", Arrays.toString(array)); 

Fetch frame count with ffmpeg


ffmpeg -i "/home/iorigins/????????????/" -f null /dev/null


result = `ffmpeg -i #{path} -f null - 2>&1`
r = result.match("frame=([0-9]+)")
p r[1]

How to add multiple classes to a ReactJS Component?

Just use a comma!

const useStyles = makeStyles((theme) => ({
 rightAlign: {
  display: 'flex',
  justifyContent: 'flex-end',
 customSpacing: {
  marginTop: theme.spacing(2.5),

<div className={(classes.rightAlign, classes.customSpacing)}>Some code</div>

How to remove "index.php" in codeigniter's path

This one did me the complete magic:

RewriteEngine on
RewriteBase /
# Hide the application and system directories by redirecting the request to index.php
RewriteRule ^(application|system|\.svn) index.php/$1 [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [QSA,L]

Hope it helps!

Are HTTPS URLs encrypted?

Linking to my answer on a duplicate question. Not only is the URL available in the browsers history, the server side logs but it's also sent as the HTTP Referer header which if you use third party content, exposes the URL to sources outside your control.

How to present a modal atop the current view in Swift

The only problem I can see in your code is that you are using CurrentContext instead of OverCurrentContext.

So, replace this:

self.modalPresentationStyle = UIModalPresentationStyle.CurrentContext
self.navigationController.modalPresentationStyle = UIModalPresentationStyle.CurrentContext

for this:

self.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext
self.navigationController.modalPresentationStyle = UIModalPresentationStyle.OverCurrentContext

django - get() returned more than one topic

In your Topic model you're allowing for more than one element to have the same topic field. You have created two with the same one already.


Now when trying to add a new learningObjective you seem to want to add it to only one Topic that matches what you're sending on the form. Since there's more than one with the same topic field get is finding 2, hence the exception.

You can either add the learningObjective to all Topics with that topic field:

for t in topic.objects.filter(topic=request.POST['Thema']):

or restrict the Topic model to have a unique topic field and keep using get, but that might not be what you want.


This problem happened with me and sovled by just add

 respond_to :html, :json

to ApplicationController file

You can Check Devise issues on Github:

How to display hexadecimal numbers in C?

i use it like this:

printf("my number is 0x%02X\n",number);
// output: my number is 0x4A

Just change number "2" to any number of chars You want to print ;)

Maven: best way of linking custom external JAR to my project?

I think you should use mvn install:install-file to populate your local repository with the library jars then you should change the scope from system to compile.

If you are starting with maven I suggest to use maven directly not IDE plugins as it adds an extra layer of complexity.

As for the error, do you put the required jars on your classpath? If you are using types from the library, you need to have access to it in the runtime as well. This has nothing to do with maven itself.

I don't understand why you want to put the library to source control - it is for sources code not binary jars.

Difference between break and continue in PHP?

break will exit the loop, while continue will start the next cycle of the loop immediately.

Disable firefox same origin policy

I wrote an add-on to overcome this issue in Firefox (Chrome, Opera version will have soon). It works with the latest Firefox version, with beautiful UI and support JS regex:

enter image description here

runOnUiThread in fragment

For Kotlin on fragment just do this

activity?.runOnUiThread(Runnable {
        //on main thread

Checking to see if one array's elements are in another array in PHP

if 'empty' is not the best choice, what about this:

if (array_intersect($people, $criminals)) {...} //when found


if (!array_intersect($people, $criminals)) {...} //when not found

How do I set the focus to the first input element in an HTML form independent from the id?

without jquery, e.g. with regular javascript:

document.querySelector('form input:not([type=hidden])').focus()

works on Safari but not Chrome 75 (april 2019)

Resize to fit image in div, and center horizontally and vertically

This is one way to do it:

Fiddle here:


<div class='container'>
    <a href='#'>
    <img class='resize_fit_center'
      src='' />


.container {
    margin: 10px;
    width: 115px;
    height: 115px;
    line-height: 115px;
    text-align: center;
    border: 1px solid red;
.resize_fit_center {
    vertical-align: middle;

Java2D: Increase the line width

You should use setStroke to set a stroke of the Graphics2D object.

The example at gives you some code examples.

The following code produces the image below:

import java.awt.*;
import java.awt.geom.Line2D;
import javax.swing.*;

public class FrameTest {
    public static void main(String[] args) {
        JFrame jf = new JFrame("Demo");
        Container cp = jf.getContentPane();
        cp.add(new JComponent() {
            public void paintComponent(Graphics g) {
                Graphics2D g2 = (Graphics2D) g;
                g2.setStroke(new BasicStroke(10));
                g2.draw(new Line2D.Float(30, 20, 80, 90));
        jf.setSize(300, 200);

enter image description here

(Note that the setStroke method is not available in the Graphics object. You have to cast it to a Graphics2D object.)

This post has been rewritten as an article here.

Aliases in Windows command prompt

Also, you can create an alias.cmd in your path (for example C:\Windows) with the command

@echo %2 %3 %4 %5 %6 > %windir%\%1.cmd

Once you do that, you can do something like this:

alias nameOfYourAlias commands to run 

And after that you can type in comman line


this will execute

commands to run 

BUT the best way for me is just adding the path of a programm.

setx PATH "%PATH%;%ProgramFiles%\Sublime Text 3" /M 

And now I run sublime as

subl index.html

How do I pass environment variables to Docker containers?

If you have the environment variables in an locally and want to set it up when the container starts, you could try

COPY <filename>.jar /<filename>.jar
ENTRYPOINT ["/bin/bash" , "-c", "source / && printenv && java -jar /<filename>.jar"]

This command would start the container with a bash shell (I want a bash shell since source is a bash command), sources the file(which sets the environment variables) and executes the jar file.

The looks like this,

export FOO="BAR"

I added the printenv command only to test that actual source command works. You should probably remove it when you confirm the source command works fine or the environment variables would appear in your docker logs.

BAT file to map to network drive without running as admin

I tried to create a mapped network driver via 'net use' with admin privilege but failed, it does not show. And if I add it through UI, it disappeared after reboot, now I made that through powershell. So, I think you can run powershell scripts from a .bat file, and the script is

New-PSDrive -Name "P" -PSProvider "FileSystem" -Root "\\Server01\Public"

add -persist at the end, you will create a persisted mapped network drive

New-PSDrive -Name "P" -PSProvider "FileSystem" -Root "\\Server01\Scripts" -Persist

for more details, refer New-PSDrive - Microsoft Docs

pandas dataframe groupby datetime month

Slightly alternative solution to @jpp's but outputting a YearMonth string:

df['YearMonth'] = pd.to_datetime(df['Date']).apply(lambda x: '{year}-{month}'.format(year=x.year, month=x.month))

res = df.groupby('YearMonth')['Values'].sum()

Find and replace entire mysql database

If you are in phpMyAdmin and you have only a minimal change, you can do this in an easy way.

  • Login to your phpMyAdmin
  • Select the database you need to perform the changes
  • Click on the search option

    enter image description here

You can always select either all the tables or any. Remember to give the search keyword, it will be used as wildcard(%).

  • Now click on Go.
  • This will give you all the tables which have the item you have searched for.

enter image description here

  • Now you can open each table one by one and perform the update A sample query generated may look like the following.

    SELECT * FROM sibeecst_passion.wp_ewwwio_images WHERE (CONVERT(id USING utf8) LIKE '%sibee%' OR CONVERT(path USING utf8) LIKE '%sibee%' OR CONVERT(image_md5 USING utf8) LIKE '%sibee%' OR CONVERT(results USING utf8) LIKE '%sibee%' OR CONVERT(gallery USING utf8) LIKE '%sibee%' OR CONVERT(image_size USING utf8) LIKE '%sibee%' OR CONVERT(orig_size USING utf8) LIKE '%sibee%' OR CONVERT(updates USING utf8) LIKE '%sibee%' OR CONVERT(updated USING utf8) LIKE '%sibee%' OR CONVERT(trace USING utf8) LIKE '%sibee%' OR CONVERT(attachment_id USING utf8) LIKE '%sibee%' OR CONVERT(resize USING utf8) LIKE '%sibee%' OR CONVERT(converted USING utf8) LIKE '%sibee%' OR CONVERT(level USING utf8) LIKE '%sibee%' OR CONVERT(pending USING utf8) LIKE '%sibee%' OR CONVERT(backup USING utf8) LIKE '%sibee%')

CASE (Contains) rather than equal statement

Pseudo code, something like:

  When CHARINDEX('lactulose', dbo.Table.Column) > 0 Then 'BP Medication'
END AS 'Medication Type'

This does not care where the keyword is found in the list and avoids depending on formatting of spaces and commas.

"Invalid form control" only in Google Chrome

$("...").attr("required"); and $("...").removeAttr("required"); 

didn't work for me until I putted all my jQuery code between that:

$(document).ready(function() {
    //jQuery code goes here

Formatting doubles for output in C#

Digits after decimal point
// just two decimal places
String.Format("{0:0.00}", 123.4567);      // "123.46"
String.Format("{0:0.00}", 123.4);         // "123.40"
String.Format("{0:0.00}", 123.0);         // "123.00"

// max. two decimal places
String.Format("{0:0.##}", 123.4567);      // "123.46"
String.Format("{0:0.##}", 123.4);         // "123.4"
String.Format("{0:0.##}", 123.0);         // "123"
// at least two digits before decimal point
String.Format("{0:00.0}", 123.4567);      // "123.5"
String.Format("{0:00.0}", 23.4567);       // "23.5"
String.Format("{0:00.0}", 3.4567);        // "03.5"
String.Format("{0:00.0}", -3.4567);       // "-03.5"

Thousands separator
String.Format("{0:0,0.0}", 12345.67);     // "12,345.7"
String.Format("{0:0,0}", 12345.67);       // "12,346"

Following code shows how can be formatted a zero (of double type).

String.Format("{0:0.0}", 0.0);            // "0.0"
String.Format("{0:0.#}", 0.0);            // "0"
String.Format("{0:#.0}", 0.0);            // ".0"
String.Format("{0:#.#}", 0.0);            // ""

Align numbers with spaces
String.Format("{0,10:0.0}", 123.4567);    // "     123.5"
String.Format("{0,-10:0.0}", 123.4567);   // "123.5     "
String.Format("{0,10:0.0}", -123.4567);   // "    -123.5"
String.Format("{0,-10:0.0}", -123.4567);  // "-123.5    "

Custom formatting for negative numbers and zero
String.Format("{0:0.00;minus 0.00;zero}", 123.4567);   // "123.46"
String.Format("{0:0.00;minus 0.00;zero}", -123.4567);  // "minus 123.46"
String.Format("{0:0.00;minus 0.00;zero}", 0.0);        // "zero"

Some funny examples
String.Format("{0:my number is 0.0}", 12.3);   // "my number is 12.3"
String.Format("{0:0aaa.bbb0}", 12.3);

Does delete on a pointer to a subclass call the base class destructor?

It is named "destructor", not "deconstructor".

Inside the destructor of each class, you have to delete all other member variables that have been allocated with new.

edit: To clarify:

Say you have

struct A {}

class B {
    A *a;
    B () : a (new A) {}
    ~B() { delete a; }

class C {
    A *a;
    C () : a (new A) {}        

int main () {
    delete new B;
    delete new C;

Allocating an instance of B and then deleting is clean, because what B allocates internally will also be deleted in the destructor.

But instances of class C will leak memory, because it allocates an instance of A which it does not release (in this case C does not even have a destructor).

How to use '-prune' option of 'find' in sh?

Normally the native way we do things in linux and the way we think is from left to right.
So you would go and write what you are looking for first:

find / -name "*.php"

Then you probably hit enter and realize you are getting too many files from directories you wish not to. Let's exclude /media to avoid searching your mounted drives.
You should now just APPEND the following to the previous command:

-print -o -path '/media' -prune

so the final command is:

find / -name "*.php" -print -o -path '/media' -prune

...............|<--- Include --->|....................|<---------- Exclude --------->|

I think this structure is much easier and correlates to the right approach

What's the best way to convert a number to a string in JavaScript?

The simplest way to convert any variable to a string is to add an empty string to that variable.

5.41 + ''    // Result: the string '5.41'
Math.PI + '' // Result: the string '3.141592653589793'

DLL load failed error when importing cv2

You can download the latest OpenCV 3.2.0 for Python 3.6 on Windows 32-bit or 64-bit machine, look for file starts withopencv_python-3.2.0-cp36-cp36m, from this unofficial site. Then type below command to install it:

  • pip install opencv_python-3.2.0-cp36-cp36m-win32.whl (32-bit version)
  • pip install opencv_python-3.2.0-cp36-cp36m-win_amd64.whl (64-bit version)

I think it would be easier.

Update on 2017-09-15:

OpenCV 3.3.0 wheel files are now available in the unofficial site and replaced OpenCV 3.2.0.

Update on 2018-02-15:

OpenCV 3.4.0 wheel files are now available in the unofficial site and replaced OpenCV 3.3.0.

Update on 2018-06-19:

OpenCV 3.4.1 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support, and replaced OpenCV 3.4.0.

Update on 2018-10-03:

OpenCV 3.4.3 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support, and replaced OpenCV 3.4.1.

Update on 2019-01-30:

OpenCV 4.0.1 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support.

Update on 2019-06-10:

OpenCV 3.4.6 and OpenCV 4.1.0 wheel files are now available in the unofficial site with CPython 3.5/3.6/3.7 support.

Pandas Merging 101

This post aims to give readers a primer on SQL-flavored merging with pandas, how to use it, and when not to use it.

In particular, here's what this post will go through:

  • The basics - types of joins (LEFT, RIGHT, OUTER, INNER)

    • merging with different column names
    • merging with multiple columns
    • avoiding duplicate merge key column in output

What this post (and other posts by me on this thread) will not go through:

  • Performance-related discussions and timings (for now). Mostly notable mentions of better alternatives, wherever appropriate.
  • Handling suffixes, removing extra columns, renaming outputs, and other specific use cases. There are other (read: better) posts that deal with that, so figure it out!

Most examples default to INNER JOIN operations while demonstrating various features, unless otherwise specified.

Furthermore, all the DataFrames here can be copied and replicated so you can play with them. Also, see this post on how to read DataFrames from your clipboard.

Lastly, all visual representation of JOIN operations have been hand-drawn using Google Drawings. Inspiration from here.

Enough Talk, just show me how to use merge!

Setup & Basics

left = pd.DataFrame({'key': ['A', 'B', 'C', 'D'], 'value': np.random.randn(4)})    
right = pd.DataFrame({'key': ['B', 'D', 'E', 'F'], 'value': np.random.randn(4)})

  key     value
0   A  1.764052
1   B  0.400157
2   C  0.978738
3   D  2.240893


  key     value
0   B  1.867558
1   D -0.977278
2   E  0.950088
3   F -0.151357

For the sake of simplicity, the key column has the same name (for now).

An INNER JOIN is represented by

This, along with the forthcoming figures all follow this convention:

  • blue indicates rows that are present in the merge result
  • red indicates rows that are excluded from the result (i.e., removed)
  • green indicates missing values that are replaced with NaNs in the result

To perform an INNER JOIN, call merge on the left DataFrame, specifying the right DataFrame and the join key (at the very least) as arguments.

left.merge(right, on='key')
# Or, if you want to be explicit
# left.merge(right, on='key', how='inner')

  key   value_x   value_y
0   B  0.400157  1.867558
1   D  2.240893 -0.977278

This returns only rows from left and right which share a common key (in this example, "B" and "D).

A LEFT OUTER JOIN, or LEFT JOIN is represented by

This can be performed by specifying how='left'.

left.merge(right, on='key', how='left')

  key   value_x   value_y
0   A  1.764052       NaN
1   B  0.400157  1.867558
2   C  0.978738       NaN
3   D  2.240893 -0.977278

Carefully note the placement of NaNs here. If you specify how='left', then only keys from left are used, and missing data from right is replaced by NaN.

And similarly, for a RIGHT OUTER JOIN, or RIGHT JOIN which is...

...specify how='right':

left.merge(right, on='key', how='right')

  key   value_x   value_y
0   B  0.400157  1.867558
1   D  2.240893 -0.977278
2   E       NaN  0.950088
3   F       NaN -0.151357

Here, keys from right are used, and missing data from left is replaced by NaN.

Finally, for the FULL OUTER JOIN, given by

specify how='outer'.

left.merge(right, on='key', how='outer')

  key   value_x   value_y
0   A  1.764052       NaN
1   B  0.400157  1.867558
2   C  0.978738       NaN
3   D  2.240893 -0.977278
4   E       NaN  0.950088
5   F       NaN -0.151357

This uses the keys from both frames, and NaNs are inserted for missing rows in both.

The documentation summarizes these various merges nicely:

enter image description here

Other JOINs - LEFT-Excluding, RIGHT-Excluding, and FULL-Excluding/ANTI JOINs

If you need LEFT-Excluding JOINs and RIGHT-Excluding JOINs in two steps.

For LEFT-Excluding JOIN, represented as

Start by performing a LEFT OUTER JOIN and then filtering (excluding!) rows coming from left only,

(left.merge(right, on='key', how='left', indicator=True)
     .query('_merge == "left_only"')
     .drop('_merge', 1))

  key   value_x  value_y
0   A  1.764052      NaN
2   C  0.978738      NaN


left.merge(right, on='key', how='left', indicator=True)

  key   value_x   value_y     _merge
0   A  1.764052       NaN  left_only
1   B  0.400157  1.867558       both
2   C  0.978738       NaN  left_only
3   D  2.240893 -0.977278       both

And similarly, for a RIGHT-Excluding JOIN,

(left.merge(right, on='key', how='right', indicator=True)
     .query('_merge == "right_only"')
     .drop('_merge', 1))

  key  value_x   value_y
2   E      NaN  0.950088
3   F      NaN -0.151357

Lastly, if you are required to do a merge that only retains keys from the left or right, but not both (IOW, performing an ANTI-JOIN),

You can do this in similar fashion—

(left.merge(right, on='key', how='outer', indicator=True)
     .query('_merge != "both"')
     .drop('_merge', 1))

  key   value_x   value_y
0   A  1.764052       NaN
2   C  0.978738       NaN
4   E       NaN  0.950088
5   F       NaN -0.151357

Different names for key columns

If the key columns are named differently—for example, left has keyLeft, and right has keyRight instead of key—then you will have to specify left_on and right_on as arguments instead of on:

left2 = left.rename({'key':'keyLeft'}, axis=1)
right2 = right.rename({'key':'keyRight'}, axis=1)

  keyLeft     value
0       A  1.764052
1       B  0.400157
2       C  0.978738
3       D  2.240893


  keyRight     value
0        B  1.867558
1        D -0.977278
2        E  0.950088
3        F -0.151357
left2.merge(right2, left_on='keyLeft', right_on='keyRight', how='inner')

  keyLeft   value_x keyRight   value_y
0       B  0.400157        B  1.867558
1       D  2.240893        D -0.977278

Avoiding duplicate key column in output

When merging on keyLeft from left and keyRight from right, if you only want either of the keyLeft or keyRight (but not both) in the output, you can start by setting the index as a preliminary step.

left3 = left2.set_index('keyLeft')
left3.merge(right2, left_index=True, right_on='keyRight')
    value_x keyRight   value_y
0  0.400157        B  1.867558
1  2.240893        D -0.977278

Contrast this with the output of the command just before (that is, the output of left2.merge(right2, left_on='keyLeft', right_on='keyRight', how='inner')), you'll notice keyLeft is missing. You can figure out what column to keep based on which frame's index is set as the key. This may matter when, say, performing some OUTER JOIN operation.

Merging only a single column from one of the DataFrames

For example, consider

right3 = right.assign(newcol=np.arange(len(right)))
  key     value  newcol
0   B  1.867558       0
1   D -0.977278       1
2   E  0.950088       2
3   F -0.151357       3

If you are required to merge only "new_val" (without any of the other columns), you can usually just subset columns before merging:

left.merge(right3[['key', 'newcol']], on='key')

  key     value  newcol
0   B  0.400157       0
1   D  2.240893       1

If you're doing a LEFT OUTER JOIN, a more performant solution would involve map:

# left['newcol'] = left['key'].map(right3.set_index('key')['newcol']))

  key     value  newcol
0   A  1.764052     NaN
1   B  0.400157     0.0
2   C  0.978738     NaN
3   D  2.240893     1.0

As mentioned, this is similar to, but faster than

left.merge(right3[['key', 'newcol']], on='key', how='left')

  key     value  newcol
0   A  1.764052     NaN
1   B  0.400157     0.0
2   C  0.978738     NaN
3   D  2.240893     1.0

Merging on multiple columns

To join on more than one column, specify a list for on (or left_on and right_on, as appropriate).

left.merge(right, on=['key1', 'key2'] ...)

Or, in the event the names are different,

left.merge(right, left_on=['lkey1', 'lkey2'], right_on=['rkey1', 'rkey2'])

Other useful merge* operations and functions

This section only covers the very basics, and is designed to only whet your appetite. For more examples and cases, see the documentation on merge, join, and concat as well as the links to the function specs.

Continue Reading

Jump to other topics in Pandas Merging 101 to continue learning:

* you are here

How to append the output to a file?

Use >> to append:

command >> file

Limit Get-ChildItem recursion depth

As of powershell 5.0, you can now use the -Depth parameter in Get-ChildItem!

You combine it with -Recurse to limit the recursion.

Get-ChildItem -Recurse -Depth 2

Creating a BAT file for python script

i did this and works: i have my project in D: and my batch file is in the desktop, if u have it in the same drive just ignore the first line and change de D directory in the second line

in the second line change the folder of the file, put your folder

in the third line change the name of the file

D: cd D:\python_proyects\example_folder\ python

Applying an ellipsis to multiline text

If you want to apply ellipsis (...) to a single line of text, CSS makes that somewhat easy with the text-overflow property. It's still a bit tricky (due to all the requirements – see below), but text-overflow makes it possible and reliable.

If, however, you want to use ellipsis on multiline text – as would be the case here – then don't expect to have any fun. CSS has no standard method for doing this, and the workarounds are hit and miss.

Ellipsis for Single Line Text

With text-overflow, ellipsis can be applied to a single line of text. The following CSS requirements must be met:

  • must have a width, max-width or flex-basis
  • must have white-space: nowrap
  • must have overflow with value other than visible
  • must be display: block or inline-block (or the functional equivalent, such as a flex item).

So this will work:

p {_x000D_
  width: 200px;_x000D_
  white-space: nowrap;_x000D_
  overflow: hidden;_x000D_
  display: inline-block;_x000D_
  text-overflow: ellipsis;_x000D_
  border: 1px solid #ddd;_x000D_
  margin: 0;_x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_

jsFiddle version

BUT, try removing the width, or letting the overflow default to visible, or removing white-space: nowrap, or using something other than a block container element, AND, ellipsis fails miserably.

One big takeaway here: text-overflow: ellipsis has no effect on multiline text. (The white-space: nowrap requirement alone eliminates that possibility.)

p {_x000D_
    width: 200px;_x000D_
    /* white-space: nowrap; */_x000D_
    height: 90px; /* new */_x000D_
    overflow: hidden;_x000D_
    display: inline-block;_x000D_
    text-overflow: ellipsis;_x000D_
    border: 1px solid #ddd;_x000D_
    margin: 0;_x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>. _x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_
  This is a test of CSS <i>text-overflow: ellipsis</i>._x000D_

jsFiddle version

Ellipsis for Multiline Text

Because CSS has no property for ellipsis on multiline text, various workarounds have been created. Several of these methods can be found here:

The Mobify link above was removed and now references an copy, but appears to be implemented in this codepen.