Programs & Examples On 2010

The version of Visual Basic .NET used in Visual Studio/Visual Basic 2010. Use VB.NET and Visual Studio 2010 tags instead unless the question is specifically about language features added in VB.NET 2010.

How to dynamically create columns in datatable and assign values to it?

If you want to create dynamically/runtime data table in VB.Net then you should follow these steps as mentioned below :

  • Create Data table object.
  • Add columns into that data table object.
  • Add Rows with values into the object.

For eg.

Dim dt As New DataTable

dt.Columns.Add("Id", GetType(Integer))
dt.Columns.Add("FirstName", GetType(String))
dt.Columns.Add("LastName", GetType(String))

dt.Rows.Add(1, "Test", "data")
dt.Rows.Add(15, "Robert", "Wich")
dt.Rows.Add(18, "Merry", "Cylon")
dt.Rows.Add(30, "Tim", "Burst")

How to open child forms positioned within MDI parent in VB.NET?

See this page for the solution!

I was able to implement the Child form inside the parent.

In the Example below Form2 should change to the name of your child form. NewMDIChild.MdiParent=me is the main form since the control that opens (shows) the child form is the parent or Me.

NewMDIChild.Show() is your child form since you associated your child form with Dim NewMDIChild As New Form2()

Protected Sub MDIChildNew_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem2.Click
   Dim NewMDIChild As New Form2()
   'Set the Parent Form of the Child window.
   NewMDIChild.MdiParent = Me
   'Display the new form.
End Sub

Simple and it works.

OpenJDK availability for Windows OS

You can find the thoroughly tested OpenJDK releases provided by Oracle at .

For example, ready to use builds of OpenJDK 10.0.2 from Oracle for 64-bit Linux, MacOS and Windows can be found at .

Send POST data using XMLHttpRequest

Just for feature readers finding this question. I found that the accepted answer works fine as long as you have a given path, but if you leave it blank it will fail in IE. Here is what I came up with:

function post(path, data, callback) {
    "use strict";
    var request = new XMLHttpRequest();

    if (path === "") {
        path = "/";
    }'POST', path, true);
    request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8');
    request.onload = function (d) {

You can you it like so:

post("", {orem: ipsum, name: binny}, function (response) {

Search for executable files using find command

I had the same issue, and the answer was in the dmenu source code: the stest utility made for that purpose. You can compile the 'stest.c' and 'arg.h' files and it should work. There is a man page for the usage, that I put there for convenience:

STEST(1)         General Commands Manual         STEST(1)

       stest - filter a list of files by properties

       stest  [-abcdefghlpqrsuwx]  [-n  file]  [-o  file]

       stest takes a list of files  and  filters  by  the
       files'  properties,  analogous  to test(1).  Files
       which pass all tests are printed to stdout. If  no
       files are given, stest reads files from stdin.

       -a     Test hidden files.

       -b     Test that files are block specials.

       -c     Test that files are character specials.

       -d     Test that files are directories.

       -e     Test that files exist.

       -f     Test that files are regular files.

       -g     Test  that  files  have  their set-group-ID
              flag set.

       -h     Test that files are symbolic links.

       -l     Test the contents of a directory  given  as
              an argument.

       -n file
              Test that files are newer than file.

       -o file
              Test that files are older than file.

       -p     Test that files are named pipes.

       -q     No  files are printed, only the exit status
              is returned.

       -r     Test that files are readable.

       -s     Test that files are not empty.

       -u     Test that files have their set-user-ID flag

       -v     Invert  the  sense  of  tests, only failing
              files pass.

       -w     Test that files are writable.

       -x     Test that files are executable.

       0      At least one file passed all tests.

       1      No files passed all tests.

       2      An error occurred.

       dmenu(1), test(1)

                        dmenu-4.6                STEST(1)

How do I make curl ignore the proxy?

Lame answer but: Remember to make sure no proxy is set in a ~/.curlrc file (...).

PHP: If internet explorer 6, 7, 8 , or 9

This is what I ended up using a variation of, which checks for IE8 and below:

if (preg_match('/MSIE\s(?P<v>\d+)/i', @$_SERVER['HTTP_USER_AGENT'], $B) && $B['v'] <= 8) {
    // Browsers IE 8 and below
} else {
    // All other browsers

Automatically creating directories with file output

The os.makedirs function does this. Try the following:

import os
import errno

filename = "/foo/bar/baz.txt"
if not os.path.exists(os.path.dirname(filename)):
    except OSError as exc: # Guard against race condition
        if exc.errno != errno.EEXIST:

with open(filename, "w") as f:

The reason to add the try-except block is to handle the case when the directory was created between the os.path.exists and the os.makedirs calls, so that to protect us from race conditions.

In Python 3.2+, there is a more elegant way that avoids the race condition above:

import os

filename = "/foo/bar/baz.txt"
os.makedirs(os.path.dirname(filename), exist_ok=True)
with open(filename, "w") as f:

How to get numeric value from a prompt box?

You have to use parseInt() to convert

For eg.

  var z = parseInt(x) + parseInt(y);

use parseFloat() if you want to handle float value.

TypeError: can only concatenate list (not "str") to list

You can use:


but using append is better since it doesn't create a new list:


How to make CREATE OR REPLACE VIEW work in SQL Server?

Borrowing from @Khan's answer, I would do:

IF OBJECT_ID('dbo.test_abc_def', 'V') IS NOT NULL
    DROP VIEW dbo.test_abc_def

CREATE VIEW dbo.test_abc_def AS
    ,VCV.yyyy AS yyyy
    ,VCV.zzzz AS zzzz

MSDN Reference

Python Requests requests.exceptions.SSLError: [Errno 8] _ssl.c:504: EOF occurred in violation of protocol

Reposting this here for others from the requests issue page:

Requests' does not support doing this before version 1. Subsequent to version 1, you are expected to subclass the HTTPAdapter, like so:

from requests.adapters import HTTPAdapter
from requests.packages.urllib3.poolmanager import PoolManager
import ssl

class MyAdapter(HTTPAdapter):
    def init_poolmanager(self, connections, maxsize, block=False):
        self.poolmanager = PoolManager(num_pools=connections,

When you've done that, you can do this:

import requests
s = requests.Session()
s.mount('https://', MyAdapter())

Any request through that session object will then use TLSv1.

Node.js res.setHeader('content-type', 'text/javascript'); pushing the response javascript as file download

You can directly set the content type like below:

res.writeHead(200, {'Content-Type': 'text/plain'});

For reference go through the nodejs Docs link.

Selecting a Linux I/O Scheduler

The aim of having the kernel support different ones is that you can try them out without a reboot; you can then run test workloads through the sytsem, measure performance, and then make that the standard one for your app.

On modern server-grade hardware, only the noop one appears to be at all useful. The others seem slower in my tests.

How to add a button programmatically in VBA next to some sheet cell data?

I think this is enough to get you on a nice path:

Sub a()
  Dim btn As Button
  Application.ScreenUpdating = False
  Dim t As Range
  For i = 2 To 6 Step 2
    Set t = ActiveSheet.Range(Cells(i, 3), Cells(i, 3))
    Set btn = ActiveSheet.Buttons.Add(t.Left, t.Top, t.Width, t.Height)
    With btn
      .OnAction = "btnS"
      .Caption = "Btn " & i
      .Name = "Btn" & i
    End With
  Next i
  Application.ScreenUpdating = True
End Sub

Sub btnS()
 MsgBox Application.Caller
End Sub

It creates the buttons and binds them to butnS(). In the btnS() sub, you should show your dialog, etc.

Mathematica graphics

Meaning of $? (dollar question mark) in shell scripts

This is the exit status of the last executed command.

For example the command true always returns a status of 0 and false always returns a status of 1:

echo $? # echoes 0
echo $? # echoes 1

From the manual: (acessible by calling man bash in your shell)

$?       Expands to the exit status of the most recently executed foreground pipeline.

By convention an exit status of 0 means success, and non-zero return status means failure. Learn more about exit statuses on wikipedia.

There are other special variables like this, as you can see on this online manual:

How to save an HTML5 Canvas as an image on a server?

I played with this two weeks ago, it's very simple. The only problem is that all the tutorials just talk about saving the image locally. This is how I did it:

1) I set up a form so I can use a POST method.

2) When the user is done drawing, he can click the "Save" button.

3) When the button is clicked I take the image data and put it into a hidden field. After that I submit the form.

document.getElementById('my_hidden').value = canvas.toDataURL('image/png');

4) When the form is submited I have this small php script:

$upload_dir = somehow_get_upload_dir();  //implement this function yourself
$img = $_POST['my_hidden'];
$img = str_replace('data:image/png;base64,', '', $img);
$img = str_replace(' ', '+', $img);
$data = base64_decode($img);
$file = $upload_dir."image_name.png";
$success = file_put_contents($file, $data);
header('Location: '.$_POST['return_url']);

Postgres - Transpose Rows to Columns

If anyone else that finds this question and needs a dynamic solution for this where you have an undefined number of columns to transpose to and not exactly 3, you can find a nice solution here:

Removing "http://" from a string

Something like this ought to do:

$url = preg_replace("|^.+?://|", "", $url); 

Removes everything up to and including the ://

Cross origin requests are only supported for HTTP but it's not cross-domain

You can also start a server without python using php interpreter.


cd /your/path/to/website/root
php -S localhost:8000

This can be useful if you want an alternative to npm, as php utility comes preinstalled on some OS' (including Mac).

Get value of Span Text

Judging by your other post: How to Get the inner text of a span in PHP. You're quite new to web programming, and need to learn about the differences between code on the client (JavaScript) and code on the server (PHP).

As for the correct approach to grabbing the span text from the client I recommend Johns answer.

These are a good place to get started.



Also I recommend using jQuery (Once you've got some JavaScript practice) it will eliminate most of the cross-browser compatability issues that you're going to have. But don't use it as a crutch to learn on, it's good to understand JavaScript too.

Why do we not have a virtual constructor in C++?

The Vpointer is created at the time of object creation. vpointer wont exists before object creation. so there is no point of making the constructor as virtual.

Convert NVARCHAR to DATETIME in SQL Server 2008

DECLARE @chr nvarchar(50) = (SELECT CONVERT(nvarchar(50), GETDATE(), 103))

SELECT @chr chars, CONVERT(date, @chr, 103) date_again

Find distance between two points on map using Google Map API V2


  • Step 1;(add this and sync in your gradle)

    compile ''  
  • Step 2:(write this in your trigger method)

    public void clicked(View view) throws JSONException {  
         JSONObject locationJsonObject = new JSONObject();
                locationJsonObject.put("origin", "54.406505,18.67708");
                locationJsonObject.put("destination", "54.446251,18.570993");
  • Step 3:(Copy & Paste in your class)

    private void LatlngCalc(JSONObject locationJsonObject) throws JSONException {
        RequestQueue queue = Volley.newRequestQueue(MainActivity.this);
        String url = "" +
                    "json?origins=" + locationJsonObject.getString("origin") + "&destinations=" + locationJsonObject.getString("destination") + "&mode=driving&" +
        StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
                new Response.Listener<String>() {
                    public void onResponse(String response) {
                        mTextView.setText("Response is: " + response.substring(0, 500));
                }, new Response.ErrorListener() {
            public void onErrorResponse(VolleyError error) {
                mTextView.setText("That didn't work!");

django change default runserver port

I was struggling with the same problem and found one solution. I guess it can help you. when you run python runserver, it will take as default ip address and 8000 as default port number which can be configured in your python environment. In your python setting, go to <your python env>\Lib\site-packages\django\core\management\commands\ and set 1. default_port = '<your_port>'
2. find this under def handle and set
if not options.get('addrport'): self.addr = '' self.port = self.default_port

Now if you run "python runserver" it will run by default on "

Enjoy coding .....

Creating a "Hello World" WebSocket example

I couldnt find a simple working example anywhere (as of Jan 19), so here is an updated version. I have chrome version 71.0.3578.98.

C# Websocket server :

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;

namespace WebSocketServer
    class Program
    static Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
    static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

    static void Main(string[] args)
        serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
        serverSocket.Listen(1); //just one socket
        serverSocket.BeginAccept(null, 0, OnAccept, null);

    private static void OnAccept(IAsyncResult result)
        byte[] buffer = new byte[1024];
            Socket client = null;
            string headerResponse = "";
            if (serverSocket != null && serverSocket.IsBound)
                client = serverSocket.EndAccept(result);
                var i = client.Receive(buffer);
                headerResponse = (System.Text.Encoding.UTF8.GetString(buffer)).Substring(0, i);
                // write received data to the console
            if (client != null)
                /* Handshaking and managing ClientSocket */
                var key = headerResponse.Replace("ey:", "`")
                          .Split('`')[1]                     // dGhlIHNhbXBsZSBub25jZQ== \r\n .......
                          .Replace("\r", "").Split('\n')[0]  // dGhlIHNhbXBsZSBub25jZQ==

                // key should now equal dGhlIHNhbXBsZSBub25jZQ==
                var test1 = AcceptKey(ref key);

                var newLine = "\r\n";

                var response = "HTTP/1.1 101 Switching Protocols" + newLine
                     + "Upgrade: websocket" + newLine
                     + "Connection: Upgrade" + newLine
                     + "Sec-WebSocket-Accept: " + test1 + newLine + newLine
                     //+ "Sec-WebSocket-Protocol: chat, superchat" + newLine
                     //+ "Sec-WebSocket-Version: 13" + newLine

                var i = client.Receive(buffer); // wait for client to send a message
                string browserSent = GetDecodedData(buffer, i);
                Console.WriteLine("BrowserSent: " + browserSent);

                //now send message to client
                client.Send(GetFrameFromString("This is message from server to client."));
                System.Threading.Thread.Sleep(10000);//wait for message to be sent
        catch (SocketException exception)
            throw exception;
            if (serverSocket != null && serverSocket.IsBound)
                serverSocket.BeginAccept(null, 0, OnAccept, null);

    public static T[] SubArray<T>(T[] data, int index, int length)
        T[] result = new T[length];
        Array.Copy(data, index, result, 0, length);
        return result;

    private static string AcceptKey(ref string key)
        string longKey = key + guid;
        byte[] hashBytes = ComputeHash(longKey);
        return Convert.ToBase64String(hashBytes);

    static SHA1 sha1 = SHA1CryptoServiceProvider.Create();
    private static byte[] ComputeHash(string str)
        return sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(str));

    //Needed to decode frame
    public static string GetDecodedData(byte[] buffer, int length)
        byte b = buffer[1];
        int dataLength = 0;
        int totalLength = 0;
        int keyIndex = 0;

        if (b - 128 <= 125)
            dataLength = b - 128;
            keyIndex = 2;
            totalLength = dataLength + 6;

        if (b - 128 == 126)
            dataLength = BitConverter.ToInt16(new byte[] { buffer[3], buffer[2] }, 0);
            keyIndex = 4;
            totalLength = dataLength + 8;

        if (b - 128 == 127)
            dataLength = (int)BitConverter.ToInt64(new byte[] { buffer[9], buffer[8], buffer[7], buffer[6], buffer[5], buffer[4], buffer[3], buffer[2] }, 0);
            keyIndex = 10;
            totalLength = dataLength + 14;

        if (totalLength > length)
            throw new Exception("The buffer length is small than the data length");

        byte[] key = new byte[] { buffer[keyIndex], buffer[keyIndex + 1], buffer[keyIndex + 2], buffer[keyIndex + 3] };

        int dataIndex = keyIndex + 4;
        int count = 0;
        for (int i = dataIndex; i < totalLength; i++)
            buffer[i] = (byte)(buffer[i] ^ key[count % 4]);

        return Encoding.ASCII.GetString(buffer, dataIndex, dataLength);

    //function to create  frames to send to client 
    /// <summary>
    /// Enum for opcode types
    /// </summary>
    public enum EOpcodeType
        /* Denotes a continuation code */
        Fragment = 0,

        /* Denotes a text code */
        Text = 1,

        /* Denotes a binary code */
        Binary = 2,

        /* Denotes a closed connection */
        ClosedConnection = 8,

        /* Denotes a ping*/
        Ping = 9,

        /* Denotes a pong */
        Pong = 10

    /// <summary>Gets an encoded websocket frame to send to a client from a string</summary>
    /// <param name="Message">The message to encode into the frame</param>
    /// <param name="Opcode">The opcode of the frame</param>
    /// <returns>Byte array in form of a websocket frame</returns>
    public static byte[] GetFrameFromString(string Message, EOpcodeType Opcode = EOpcodeType.Text)
        byte[] response;
        byte[] bytesRaw = Encoding.Default.GetBytes(Message);
        byte[] frame = new byte[10];

        int indexStartRawData = -1;
        int length = bytesRaw.Length;

        frame[0] = (byte)(128 + (int)Opcode);
        if (length <= 125)
            frame[1] = (byte)length;
            indexStartRawData = 2;
        else if (length >= 126 && length <= 65535)
            frame[1] = (byte)126;
            frame[2] = (byte)((length >> 8) & 255);
            frame[3] = (byte)(length & 255);
            indexStartRawData = 4;
            frame[1] = (byte)127;
            frame[2] = (byte)((length >> 56) & 255);
            frame[3] = (byte)((length >> 48) & 255);
            frame[4] = (byte)((length >> 40) & 255);
            frame[5] = (byte)((length >> 32) & 255);
            frame[6] = (byte)((length >> 24) & 255);
            frame[7] = (byte)((length >> 16) & 255);
            frame[8] = (byte)((length >> 8) & 255);
            frame[9] = (byte)(length & 255);

            indexStartRawData = 10;

        response = new byte[indexStartRawData + length];

        int i, reponseIdx = 0;

        //Add the frame bytes to the reponse
        for (i = 0; i < indexStartRawData; i++)
            response[reponseIdx] = frame[i];

        //Add the data bytes to the response
        for (i = 0; i < length; i++)
            response[reponseIdx] = bytesRaw[i];

        return response;

Client html and javascript:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"_x000D_
<html xmlns="">_x000D_
    <script type="text/javascript">_x000D_
        var socket = new WebSocket('ws://localhost:8080/websession');_x000D_
        socket.onopen = function() {_x000D_
           // alert('handshake successfully established. May send data now...');_x000D_
     socket.send("Hi there from browser.");_x000D_
  socket.onmessage = function (evt) {_x000D_
                //alert("About to receive data");_x000D_
                var received_msg =;_x000D_
                alert("Message received = "+received_msg);_x000D_
        socket.onclose = function() {_x000D_
            alert('connection closed');_x000D_

ALTER COLUMN in sqlite

There's no ALTER COLUMN in sqlite.

I believe your only option is to:

  • Rename the table to a temporary name
  • Create a new table without the NOT NULL constraint
  • Copy the content of the old table to the new one
  • Remove the old table

This other Stackoverflow answer explains the process in details

PowerShell try/catch/finally

That is very odd.

I went through ItemNotFoundException's base classes and tested the following multiple catches to see what would catch it:

try {
  remove-item C:\nonexistent\file.txt -erroraction stop
catch [System.Management.Automation.ItemNotFoundException] {
  write-host 'ItemNotFound'
catch [System.Management.Automation.SessionStateException] {
  write-host 'SessionState'
catch [System.Management.Automation.RuntimeException] {
  write-host 'RuntimeException'
catch [System.SystemException] {
  write-host 'SystemException'
catch [System.Exception] {
  write-host 'Exception'
catch {
  write-host 'well, darn'

As it turns out, the output was 'RuntimeException'. I also tried it with a different exception CommandNotFoundException:

try {
catch [System.Management.Automation.CommandNotFoundException] {
  write-host 'CommandNotFoundException'
catch {
  write-host 'well, darn'

That output 'CommandNotFoundException' correctly.

I vaguely remember reading elsewhere (though I couldn't find it again) of problems with this. In such cases where exception filtering didn't work correctly, they would catch the closest Type they could and then use a switch. The following just catches Exception instead of RuntimeException, but is the switch equivalent of my first example that checks all base types of ItemNotFoundException:

try {
  Remove-Item C:\nonexistent\file.txt -ErrorAction Stop
catch [System.Exception] {
  switch($_.Exception.GetType().FullName) {
    'System.Management.Automation.ItemNotFoundException' {
      write-host 'ItemNotFound'
    'System.Management.Automation.SessionStateException' {
      write-host 'SessionState'
    'System.Management.Automation.RuntimeException' {
      write-host 'RuntimeException'
    'System.SystemException' {
      write-host 'SystemException'
    'System.Exception' {
      write-host 'Exception'
    default {'well, darn'}

This writes 'ItemNotFound', as it should.

How to center a checkbox in a table cell?

How about this...

Check out my example on jsFiddle: Code snippet:

td {
  text-align: center;
  /* center checkbox horizontally */
  vertical-align: middle;
  /* center checkbox vertically */

table {
  border: 1px solid;
  width: 200px;

tr {
  height: 80px;
      <input type="checkbox" name="myTextEditBox" value="checked" /> checkbox

When should I use Kruskal as opposed to Prim (and vice versa)?

Kruskal can have better performance if the edges can be sorted in linear time, or are already sorted.

Prim's better if the number of edges to vertices is high.

Differences between dependencyManagement and dependencies in Maven

It's like you said; dependencyManagementis used to pull all the dependency information into a common POM file, simplifying the references in the child POM file.

It becomes useful when you have multiple attributes that you don't want to retype in under multiple children projects.

Finally, dependencyManagement can be used to define a standard version of an artifact to use across multiple projects.

What is the best way to delete a value from an array in Perl?

Use splice if you already know the index of the element you want to delete.

Grep works if you are searching.

If you need to do a lot of these, you will get much better performance if you keep your array in sorted order, since you can then do binary search to find the necessary index.

If it makes sense in your context, you may want to consider using a "magic value" for deleted records, rather then deleting them, to save on data movement -- set deleted elements to undef, for example. Naturally, this has its own issues (if you need to know the number of "live" elements, you need to keep track of it separately, etc), but may be worth the trouble depending on your application.

Edit Actually now that I take a second look -- don't use the grep code above. It would be more efficient to find the index of the element you want to delete, then use splice to delete it (the code you have accumulates all the non-matching results..)

my $index = 0;
$index++ until $arr[$index] eq 'foo';
splice(@arr, $index, 1);

That will delete the first occurrence. Deleting all occurrences is very similar, except you will want to get all indexes in one pass:

my @del_indexes = grep { $arr[$_] eq 'foo' } 0..$#arr;

The rest is left as an excercise for the reader -- remember that the array changes as you splice it!

Edit2 John Siracusa correctly pointed out I had a bug in my example.. fixed, sorry about that.

Counting the number of elements in array

This expands on the answer by Denis Bubnov.

I used this to find child values of array elements—namely if there was a anchor field in paragraphs on a Drupal 8 site to build a table of contents.

{% set count = 0 %}
{% for anchor in items %}
    {% if anchor.content['#paragraph'].field_anchor_link.0.value %}
        {% set count = count + 1 %}
    {% endif %}
{% endfor %}

{% if count > 0 %}
 ---  build the toc here --
{% endif %}

How to copy Outlook mail message into excel using VBA or Macros

Since you have not mentioned what needs to be copied, I have left that section empty in the code below.

Also you don't need to move the email to the folder first and then run the macro in that folder. You can run the macro on the incoming mail and then move it to the folder at the same time.

This will get you started. I have commented the code so that you will not face any problem understanding it.

First paste the below mentioned code in the outlook module.


  1. Click on Tools~~>Rules and Alerts
  2. Click on "New Rule"
  3. Click on "start from a blank rule"
  4. Select "Check messages When they arrive"
  5. Under conditions, click on "with specific words in the subject"
  6. Click on "specific words" under rules description.
  7. Type the word that you want to check in the dialog box that pops up and click on "add".
  8. Click "Ok" and click next
  9. Select "move it to specified folder" and also select "run a script" in the same box
  10. In the box below, specify the specific folder and also the script (the macro that you have in module) to run.
  11. Click on finish and you are done.

When the new email arrives not only will the email move to the folder that you specify but data from it will be exported to Excel as well.


Const xlUp As Long = -4162

Sub ExportToExcel(MyMail As MailItem)
    Dim strID As String, olNS As Outlook.Namespace
    Dim olMail As Outlook.MailItem
    Dim strFileName As String

    '~~> Excel Variables
    Dim oXLApp As Object, oXLwb As Object, oXLws As Object
    Dim lRow As Long

    strID = MyMail.EntryID
    Set olNS = Application.GetNamespace("MAPI")
    Set olMail = olNS.GetItemFromID(strID)

    '~~> Establish an EXCEL application object
    On Error Resume Next
    Set oXLApp = GetObject(, "Excel.Application")

    '~~> If not found then create new instance
    If Err.Number <> 0 Then
        Set oXLApp = CreateObject("Excel.Application")
    End If
    On Error GoTo 0

    '~~> Show Excel
    oXLApp.Visible = True

    '~~> Open the relevant file
    Set oXLwb = oXLApp.Workbooks.Open("C:\Sample.xls")

    '~~> Set the relevant output sheet. Change as applicable
    Set oXLws = oXLwb.Sheets("Sheet1")

    lRow = oXLws.Range("A" & oXLApp.Rows.Count).End(xlUp).Row + 1

    '~~> Write to outlook
    With oXLws
        '~~> Code here to output data from email to Excel File
        '~~> For example
        .Range("A" & lRow).Value = olMail.Subject
        .Range("B" & lRow).Value = olMail.SenderName
    End With

    '~~> Close and Clean up Excel
    oXLwb.Close (True)
    Set oXLws = Nothing
    Set oXLwb = Nothing
    Set oXLApp = Nothing

    Set olMail = Nothing
    Set olNS = Nothing
End Sub


To extract the contents from your email body, you can split it using SPLIT() and then parsing out the relevant information from it. See this example

Dim MyAr() As String

MyAr = Split(olMail.body, vbCrLf)

For i = LBound(MyAr) To UBound(MyAr)
    '~~> This will give you the contents of your email
    '~~> on separate lines
    Debug.Print MyAr(i)
Next i

Spell Checker for Python

You can use the autocorrect lib to spell check in python.
Example Usage:

from autocorrect import Speller

spell = Speller(lang='en')




How to convert int to float in C?

No, because you do the expression using integers, so you divide the integer 50 by the integer 100, which results in the integer 0. Type cast one of them to a float and it should work.

How to turn NaN from parseInt into 0 for an empty string?

I created a 2 prototype to handle this for me, one for a number, and one for a String.

// This is a safety check to make sure the prototype is not already defined.
Function.prototype.method = function (name, func) {
    if (!this.prototype[name]) {
        this.prototype[name] = func;
        return this;

// returns the int value or -1 by default if it fails
Number.method('tryParseInt', function (defaultValue) {
    return parseInt(this) == this ? parseInt(this) : (defaultValue === undefined ? -1 : defaultValue);

// returns the int value or -1 by default if it fails
String.method('tryParseInt', function (defaultValue) {
    return parseInt(this) == this ? parseInt(this) : (defaultValue === undefined ? -1 : defaultValue);

If you dont want to use the safety check, use

String.prototype.tryParseInt = function(){
    /*Method body here*/
Number.prototype.tryParseInt = function(){
     /*Method body here*/

Example usage:

var test = 1;
console.log(test.tryParseInt()); // returns 1

var test2 = '1';
console.log(test2.tryParseInt()); // returns 1

var test3 = '1a';
console.log(test3.tryParseInt()); // returns -1 as that is the default

var test4 = '1a';
console.log(test4.tryParseInt(0));// returns 0, the specified default value

Adding a column after another column within SQL

It depends on what database you are using. In MySQL, you would use the "ALTER TABLE" syntax. I don't remember exactly how, but it would go something like this if you wanted to add a column called 'newcol' that was a 200 character varchar:

ALTER TABLE example ADD newCol VARCHAR(200) AFTER otherCol;

Favorite Visual Studio keyboard shortcuts

I have two that I use a lot, the first is standard, the second you have to map:

Ctrl+A, Ctrl+E, F (Select All, Format Selection)

Ctrl+E, R (Remove Unused Usings and Sort)

Both help pay down the "cruft debt" early and often

Remove folder and its contents from git/GitHub's history

For Windows user, please note to use " instead of ' Also added -f to force the command if another backup is already there.

git filter-branch -f --tree-filter "rm -rf FOLDERNAME" --prune-empty HEAD
git for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d
echo FOLDERNAME/ >> .gitignore
git add .gitignore
git commit -m "Removing FOLDERNAME from git history"
git gc
git push origin master --force

How to expand and compute log(a + b)?

In general, one doesn't expand out log(a + b); you just deal with it as is. That said, there are occasionally circumstances where it makes sense to use the following identity:

log(a + b) = log(a * (1 + b/a)) = log a + log(1 + b/a)

(In fact, this identity is often used when implementing log in math libraries).

How to turn off the Eclipse code formatter for certain sections of Java code?

Instead of turning the formatting off, you can configure it not to join already wrapped lines. Similar to Jitter's response, here's for Eclipse STS:

Properties ? Java Code Style ? Formatter ? Enable project specific settings OR Configure Workspace Settings ? Edit ? Line Wrapping (tab) ? check "Never join already wrapped lines"

Save, apply.

enter image description here

How do I write out a text file in C# with a code page other than UTF-8?

using System.IO;
using System.Text;

using (StreamWriter sw = new StreamWriter(File.Open(myfilename, FileMode.Create), Encoding.WhateverYouWant))
    sw.WriteLine("my text...");     

An alternate way of getting your encoding:

using System.IO;
using System.Text;

using (var sw  = new StreamWriter(File.Open(@"c:\myfile.txt", FileMode.CreateNew), Encoding.GetEncoding("iso-8859-1"))) {
    sw.WriteLine("my text...");             

Check out the docs for the StreamWriter constructor.

How to format Joda-Time DateTime to only mm/dd/yyyy?


You can: create a constant:

private static final DateTimeFormatter DATE_FORMATTER_YYYY_MM_DD =
          DateTimeFormat.forPattern("yyyy-MM-dd"); // or whatever pattern that you need.

This DateTimeFormat is importing from: (be careful with that)

import org.joda.time.format.DateTimeFormat; import org.joda.time.format.DateTimeFormatter;

Parse the Date with:

DateTime.parse(dateTimeScheduled.toString(), DATE_FORMATTER_YYYY_MM_DD);


if want datetime:

DateTime.parse("201711201515", DateTimeFormat.forPattern("yyyyMMddHHmm")).withTimeAtStartOfDay();

Max retries exceeded with URL in requests

just import time and add :


somewhere in the for loop, to avoid sending too many request to the server in a short time. the number 6 means: 6 seconds. keep testing numbers starting from 1, until you reach the minimum seconds that will help to avoid the problem.

How to create text file and insert data to that file on Android

I'm using Kotlin here

Just adding the information in here, you can also create readable file outside Private Directory for the apps by doing this example

var teks="your teks"
var NamaFile="Text1.txt"
var strwrt:FileWriter

after that you can acces File Manager and look up on the Internal Storage. Text1.txt will be on there below all the folder.

ES6 class variable alternatives

This is a bit hackish combo of static and get works for me

class ConstantThingy{
        static get NO_REENTER__INIT() {
            if(ConstantThingy._NO_REENTER__INIT== null){
                ConstantThingy._NO_REENTER__INIT = new ConstantThingy(false,true);
            return ConstantThingy._NO_REENTER__INIT;

elsewhere used

var conf = ConstantThingy.NO_REENTER__INIT;

How to run a class from Jar which is not the Main-Class in its Manifest file

You can create your jar without Main-Class in its Manifest file. Then :

java -cp MyJar.jar com.mycomp.myproj.dir2.MainClass2 /home/myhome/ /home/myhome/input.txt

How to generate different random numbers in a loop in C++?

The time function probably returns the same value during each iteration of the loop.

Try initializing the random seed before the loop.

Compare string with all values in list

In Python you may use the in operator. You can do stuff like this:

>>> "c" in "abc"

Taking this further, you can check for complex structures, like tuples:

>>> (2, 4, 8) in ((1, 2, 3), (2, 4, 8))

What are passive event listeners?

Passive event listeners are an emerging web standard, new feature shipped in Chrome 51 that provide a major potential boost to scroll performance. Chrome Release Notes.

It enables developers to opt-in to better scroll performance by eliminating the need for scrolling to block on touch and wheel event listeners.

Problem: All modern browsers have a threaded scrolling feature to permit scrolling to run smoothly even when expensive JavaScript is running, but this optimization is partially defeated by the need to wait for the results of any touchstart and touchmove handlers, which may prevent the scroll entirely by calling preventDefault() on the event.

Solution: {passive: true}

By marking a touch or wheel listener as passive, the developer is promising the handler won't call preventDefault to disable scrolling. This frees the browser up to respond to scrolling immediately without waiting for JavaScript, thus ensuring a reliably smooth scrolling experience for the user.

document.addEventListener("touchstart", function(e) {
    console.log(e.defaultPrevented);  // will be false
    e.preventDefault();   // does nothing since the listener is passive
    console.log(e.defaultPrevented);  // still false
}, Modernizr.passiveeventlisteners ? {passive: true} : false);

DOM Spec , Demo Video , Explainer Doc

File is universal (three slices), but it does not contain a(n) ARMv7-s slice error for static libraries on iOS, anyway to bypass?

Try to remove armv7s from project's "Valid architecture" to release from this issue for iOS 5.1 phone

Git status ignore line endings / identical files / windows & linux environment / dropbox / mled

This answer seems relevant since the OP makes reference to a need for a multi-OS solution. This Github help article details available approaches for handling lines endings cross-OS. There are global and per-repo approaches to managing cross-os line endings.

Global approach

Configure Git line endings handling on Linux or OS X:

git config --global core.autocrlf input

Configure Git line endings handling on Windows:

git config --global core.autocrlf true

Per-repo approach:

In the root of your repo, create a .gitattributes file and define line ending settings for your project files, one line at a time in the following format: path_regex line-ending-settings where line-ending-settings is one of the following:

  • text
  • binary (files that Git should not modify line endings for - as this can cause some image types such as PNGs not to render in a browser)

The text value can be configured further to instruct Git on how to handle line endings for matching files:

  • text - Changes line endings to OS native line endings.
  • text eol=crlf - Converts line endings to CRLF on checkout.
  • text eol=lf - Converts line endings to LF on checkout.
  • text=auto - Sensible default that leaves line handle up to Git's discretion.

Here is the content of a sample .gitattributes file:

# Set the default behavior for all files.
* text=auto

# Normalized and converts to 
# native line endings on checkout.
*.c text
*.h text

# Convert to CRLF line endings on checkout.
*.sln text eol=crlf

# Convert to LF line endings on checkout.
*.sh text eol=lf

# Binary files.
*.png binary
*.jpg binary

More on how to refresh your repo after changing line endings settings here. Tldr:

backup your files with Git, delete every file in your repository (except the .git directory), and then restore the files all at once. Save your current files in Git, so that none of your work is lost.

git add . -u

git commit -m "Saving files before refreshing line endings"

Remove the index and force Git to rescan the working directory.

rm .git/index

Rewrite the Git index to pick up all the new line endings.

git reset

Show the rewritten, normalized files.

In some cases, this is all that needs to be done. Others may need to complete the following additional steps:

git status

Add all your changed files back, and prepare them for a commit. This is your chance to inspect which files, if any, were unchanged.

git add -u

It is perfectly safe to see a lot of messages here that read[s] "warning: CRLF will be replaced by LF in file."

Rewrite the .gitattributes file.

git add .gitattributes

Commit the changes to your repository.

git commit -m "Normalize all the line endings"

Number of rows affected by an UPDATE in PL/SQL

SQL%ROWCOUNT can also be used without being assigned (at least from Oracle 11g).

As long as no operation (updates, deletes or inserts) has been performed within the current block, SQL%ROWCOUNT is set to null. Then it stays with the number of line affected by the last DML operation:

say we have table CLIENT

create table client (
  val_cli integer
 ,status varchar2(10)

We would test it this way:

  dbms_output.put_line('Value when entering the block:'||sql%rowcount);

  insert into client 
            select 1, 'void' from dual
  union all select 4, 'void' from dual
  union all select 1, 'void' from dual
  union all select 6, 'void' from dual
  union all select 10, 'void' from dual;  
  dbms_output.put_line('Number of lines affected by previous DML operation:'||sql%rowcount);

  for val in 1..10
      update client set status = 'updated' where val_cli = val;
      if sql%rowcount = 0 then
        dbms_output.put_line('no client with '||val||' val_cli.');
      elsif sql%rowcount = 1 then
        dbms_output.put_line(sql%rowcount||' client updated for '||val);
      else -- >1
        dbms_output.put_line(sql%rowcount||' clients updated for '||val);
      end if;
  end loop;  

Resulting in:

Value when entering the block:
Number of lines affected by previous DML operation:5
2 clients updated for 1
no client with 2 val_cli.
no client with 3 val_cli.
1 client updated for 4
no client with 5 val_cli.
1 client updated for 6
no client with 7 val_cli.
no client with 8 val_cli.
no client with 9 val_cli.
1 client updated for 10

VBA Macro to compare all cells of two Excel files

A very simple check you can do with Cell formulas:

Sheet 1 (new - old)


Sheet 2 (old - new)


This formulas should work for an ENGLISH Excel. For other languages they need to be translated. (For German i can assist)

You need to open all three Excel Documents, then copy the first formula into A1 of your sheet 1 and the second into A1 of sheet 2. Now click in A1 of the first cell and mark "Ref_New", now you can select your reference, go to the new file and click in the A1, go back to sheet1 and do the same for "Ref_Old" with the old file. Replace also the other "Ref_New".

Doe the same for Sheet two.

Now copy the formaula form A1 over the complete range where zour data is in the old and the new file.

But two cases are not covered here:

  1. In the compared cell of New and Old is the same data (Resulting Cell will be empty)
  2. In the compared cell of New and Old is diffe data (Resulting Cell will be empty)

To cover this two cases also, you should create your own function, means learn VBA. A very useful Excel page is

RestTemplate: How to send URL and query parameters together

I would use buildAndExpand from UriComponentsBuilder to pass all types of URI parameters.

For example:

String url = "{planet}/moons/{moon}";

// URI (URL) parameters
Map<String, String> urlParams = new HashMap<>();
urlParams.put("planets", "Mars");
urlParams.put("moons", "Phobos");

// Query parameters
UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(url)
        // Add query parameter
        .queryParam("firstName", "Mark")
        .queryParam("lastName", "Watney");

 * Console output:
 */ , HttpMethod.PUT,
        requestEntity, class_p);

 * Log entry:
 * org.springframework.web.client.RestTemplate Created PUT request for ""

How to Find Item in Dictionary Collection?

thisTag = _tags.FirstOrDefault(t => t.Key == tag);

is an inefficient and a little bit strange way to find something by key in a dictionary. Looking things up for a Key is the basic function of a Dictionary.

The basic solution would be:

if (_tags.Containskey(tag)) { string myValue = _tags[tag]; ... }

But that requires 2 lookups.

TryGetValue(key, out value) is more concise and efficient, it only does 1 lookup. And that answers the last part of your question, the best way to do a lookup is:

string myValue;
if (_tags.TryGetValue(tag, out myValue)) { /* use myValue */ }

VS 2017 update, for C# 7 and beyond we can declare the result variable inline:

if (_tags.TryGetValue(tag, out string myValue))
    // use myValue;
// use myValue, still in scope, null if not found

Error in contrasts when defining a linear model in R

This is a variation to the answer provided by @Metrics and edited by @Max Ghenis...

l <- sapply(iris, function(x) is.factor(x))
m <- iris[,l]

n <- sapply( m, function(x) { y <- summary(x)/length(x)
len <- length(y[y<0.005 | y>0.995])
cbind(len,t(y))} )

drop_cols_df <- data.frame(var = names(l[l]), 
                           status = ifelse(as.vector(t(n[1,]))==0,"NODROP","DROP" ),
                           level1 = as.vector(t(n[2,])),
                           level2 = as.vector(t(n[3,])))

Here, after identifying factor variables, the second sapply computes what percent of records belong to each level / category of the variable. Then it identifies number of levels over 99.5% or below 0.5% incidence rate (my arbitrary thresholds).

It then goes on to return the number of valid levels and the incidence rate of each level in each categorical variable.

Variables with zero levels crossing the thresholds should not be dropped, while the other should be dropped from the linear model.

The last data frame makes viewing the results easy. It's hard coded for this data set since all factor variables are binomial. This data frame can be made generic easily enough.

How to beautify JSON in Python?

It looks like jsbeautifier open sourced their tools and packaged them as Python and JS libs, and as CLI tools. It doesn't look like they call out to a web service, but I didn't check too closely. See the github repo with install instructions.

From their docs for Python CLI and library usage:

To beautify using python:

$ pip install jsbeautifier
$ js-beautify file.js

Beautified output goes to stdout.

To use jsbeautifier as a library is simple:

import jsbeautifier
res = jsbeautifier.beautify('your javascript string')
res = jsbeautifier.beautify_file('some_file.js')

...or, to specify some options:

opts = jsbeautifier.default_options()
opts.indent_size = 2
res = jsbeautifier.beautify('some javascript', opts)

If you want to pass a string instead of a filename, and you are using bash, then you can use process substitution like so:

$ js-beautify <(echo '{"some": "json"}')

SQL how to increase or decrease one for a int column in one command

UPDATE Orders Order
SET Order.Quantity =  Order.Quantity - 1
WHERE SomeCondition(Order)

As far as I know there is no build-in support for INSERT-OR-UPDATE in SQL. I suggest to create a stored procedure or use a conditional query to achiev this. Here you can find a collection of solutions for different databases.

Why does git say "Pull is not possible because you have unmerged files"?

You have some files locally that need to be merged before you can pull. You could checkout the files and then pull to overwrite your local files.

git checkout app/config/app.php app/config/database.php app/routes.php
git pull origin master

Sorting a vector in descending order

I don't think you should use either of the methods in the question as they're both confusing, and the second one is fragile as Mehrdad suggests.

I would advocate the following, as it looks like a standard library function and makes its intention clear:

#include <iterator>

template <class RandomIt>
void reverse_sort(RandomIt first, RandomIt last)
    std::sort(first, last, 
        std::greater<typename std::iterator_traits<RandomIt>::value_type>());

How to check whether a file is empty or not?

if you have the file object, then

>>> import os
>>> with open('new_file.txt') as my_file:
..., os.SEEK_END) # go to end of file
...     if my_file.tell(): # if current position is truish (i.e != 0)
... # rewind the file for later use 
...     else:
...         print "file is empty"
file is empty

Doctrine and LIKE query

Actually you just need to tell doctrine who's your repository class, if you don't, doctrine uses default repo instead of yours.


Want to show/hide div based on dropdown box selection

You need to either put your code at the end of the page or wrap it in a document ready call, otherwise you're trying to execute code on elements that don't yet exist. Also, you can reduce your code to:

$('#purpose').on('change', function () {
    $("#business").css('display', (this.value == '1') ? 'block' : 'none');

jsFiddle example

Number input type that takes only integers?

Currently, it is not possible to prevent a user from writing decimal values in your input with HTML only. You have to use javascript.

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

Use saveas:

% ...

This way, the figure is plotted, and automatically saved to '.jpg' and '.fig'. You don't need to wait for the plot to appear and click 'save as' in the menu. Way to go if you need to plot/save a lot of figures.

If you really do not want to let the plot appear (it has to be loaded anyway, can't avoid that, else there is also nothing to save), you can hide it:


get string value from HashMap depending on key name

You can use the get(Object key) method from the HashMap. Be aware that i many cases your Key Class should override the equals method, to be a useful class for a Map key.

Find the similarity metric between two strings

Fuzzy Wuzzy is a package that implements Levenshtein distance in python, with some helper functions to help in certain situations where you may want two distinct strings to be considered identical. For example:

>>> fuzz.ratio("fuzzy wuzzy was a bear", "wuzzy fuzzy was a bear")
>>> fuzz.token_sort_ratio("fuzzy wuzzy was a bear", "wuzzy fuzzy was a bear")

Issue in installing php7.2-mcrypt

As an alternative, you can install 7.1 version of mcrypt and create a symbolic link to it:

Install php7.1-mcrypt:

sudo apt install php7.1-mcrypt

Create a symbolic link:

sudo ln -s /etc/php/7.1/mods-available/mcrypt.ini /etc/php/7.2/mods-available

After enabling mcrypt by sudo phpenmod mcrypt, it gets available.

Simplest SOAP example

This is the simplest JavaScript SOAP Client I can create.

    <title>SOAP JavaScript Client Test</title>
    <script type="text/javascript">
        function soap() {
            var xmlhttp = new XMLHttpRequest();
  'POST', '', true);

            // build SOAP request
            var sr =
                '<?xml version="1.0" encoding="utf-8"?>' +
                '<soapenv:Envelope ' + 
                    'xmlns:xsi="" ' +
                    'xmlns:api="" ' +
                    'xmlns:xsd="" ' +
                    'xmlns:soapenv="">' +
                    '<soapenv:Body>' +
                        '<api:some_api_call soapenv:encodingStyle="">' +
                            '<username xsi:type="xsd:string">login_username</username>' +
                            '<password xsi:type="xsd:string">password</password>' +
                        '</api:some_api_call>' +
                    '</soapenv:Body>' +

            xmlhttp.onreadystatechange = function () {
                if (xmlhttp.readyState == 4) {
                    if (xmlhttp.status == 200) {
                        // alert('done. use firebug/console to see network response');
            // Send the POST request
            xmlhttp.setRequestHeader('Content-Type', 'text/xml');
            // send request
            // ...
    <form name="Demo" action="" method="post">
            <input type="button" value="Soap" onclick="soap();" />
</html> <!-- typo -->

How to compile multiple java source files in command line

Here is another example, for compiling a java file in a nested directory.

I was trying to build this from the command line. This is an example from 'gradle', which has dependency 'commons-collection.jar'. For more info, please see 'gradle: java quickstart' example. -- of course, you would use the 'gradle' tools to build it. But i thought to extend this example, for a nested java project, with a dependent jar.

Note: You need the 'gradle binary or source' distribution for this, example code is in: 'samples/java/quickstart'

% mkdir -p temp/classes
% curl --get \ \
        --output commons-collections-3.2.2.jar

% javac -g -classpath commons-collections-3.2.2.jar \
     -sourcepath src/main/java -d temp/classes \

% jar cf my_example.jar -C temp/classes org/gradle/Person.class
% jar tvf my_example.jar
   0 Wed Jun 07 14:11:56 CEST 2017 META-INF/
  69 Wed Jun 07 14:11:56 CEST 2017 META-INF/MANIFEST.MF
 519 Wed Jun 07 13:58:06 CEST 2017 org/gradle/Person.class

UITextField text change event

to set the event listener:

[self.textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

to actually listen:

- (void)textFieldDidChange:(UITextField *)textField {
    NSLog(@"text changed: %@", textField.text);

How to do logging in React Native?

There are several ways to achieve this, I am listing them and including cons in using them also. You can use:

  1. console.log and view logging statements on, without opting out for remote debugging option from dev tools, Android Studio and Xcode. or you can opt out for remote debugging option and view logging on chrome dev tools or vscode or any other editor that supports debugging, you have to be cautious as this will slow down the process as a whole.
  2. You can use console.warn but then your mobile screen would be flooded with those weird yellow boxes which might or might not be feasible according to your situation.
  3. Most effective method that I came across is to use a third party tool, Reactotron. A simple and easy to configure tool that enables you to see each logging statement of different levels (error, debug, warn, etc.). It provides you with the GUI tool that shows all the logging of your app without slowing down the performance.

How to check iOS version?

There are version like 7.0 or 6.0.3, so we can simply convert version into numerics to compare. if version is like 7.0, simply append another ".0" to it and then take its numeric value.

 int version;
 NSString* iosVersion=[[UIDevice currentDevice] systemVersion];
 NSArray* components=[iosVersion componentsSeparatedByString:@"."];
 if ([components count]==2) {
    iosVersion=[NSString stringWithFormat:@"%@.0",iosVersion];

 iosVersion=[iosVersion stringByReplacingOccurrencesOfString:@"." withString:@""];
 version=[iosVersion integerValue];

For 6.0.0

  if (version==600) {
    // Do something

for 7.0

 if (version==700) {
   // Do something

How to make a programme continue to run after log out from ssh?

You should try using nohup and running it in the background:

nohup sleep 3600 &

cordova Android requirements failed: "Could not find an installed version of Gradle"

I m using Cordova version 7.0.1 and Cordova android version is 6.2.3. I was facing the issue while performing android build. I m using only Cordova CLI and not using android studio at all.

The quick workaround for this issue before its official fixed in Cordova is as follows:

  1. Look for check_reqs.js file under platforms\android\cordova\lib folder
  2. Edit the else part of androidStudioPath variable null check in get_gradle_wrapper function as below:

Existing code:

else { //OK, let's try to check for Gradle! return forgivingWhichSync('gradle'); }

Modified code:

else { //OK, let's try to check for Gradle! var sdkDir = process.env['ANDROID_HOME']; return path.join(sdkDir, 'tools', 'templates', 'gradle', 'wrapper', 'gradlew'); }

NOTE: This change needs to be done everytime when the android platform is removed and re-added

UPDATE: In my case, I already had gradle wrapper inside my android SDK and I dint find necessity to install gradle explicitly. Hence, I made this workaround to minimize my impact and effort

forEach is not a function error with JavaScript array

First option: invoke forEach indirectly

The parent.children is an Array like object. Use the following solution:

const parent = this.el.parentElement;, child => {

The parent.children is NodeList type, which is an Array like object because:

  • It contains the length property, which indicates the number of nodes
  • Each node is a property value with numeric name, starting from 0: {0: NodeObject, 1: NodeObject, length: 2, ...}

See more details in this article.

Second option: use the iterable protocol

parent.children is an HTMLCollection: which implements the iterable protocol. In an ES2015 environment, you can use the HTMLCollection with any construction that accepts iterables.

Use HTMLCollection with the spread operatator:

const parent = this.el.parentElement;

[...parent.children].forEach(child => {

Or with the for..of cycle (which is my preferred option):

const parent = this.el.parentElement;

for (const child of parent.children) {

Android: How to bind spinner to custom object list?

By far the simplest way that I've found:

public String toString() {
    return this.label;           

Now you can stick any object in your spinner, and it will display the specified label.

what does numpy ndarray shape do?

Unlike it's most popular commercial competitor, numpy pretty much from the outset is about "arbitrary-dimensional" arrays, that's why the core class is called ndarray. You can check the dimensionality of a numpy array using the .ndim property. The .shape property is a tuple of length .ndim containing the length of each dimensions. Currently, numpy can handle up to 32 dimensions:

a = np.ones(32*(1,))
# array([[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[ 1.]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]])
# (1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)
# 32

If a numpy array happens to be 2d like your second example, then it's appropriate to think about it in terms of rows and columns. But a 1d array in numpy is truly 1d, no rows or columns.

If you want something like a row or column vector you can achieve this by creating a 2d array with one of its dimensions equal to 1.

a = np.array([[1,2,3]]) # a 'row vector'
b = np.array([[1],[2],[3]]) # a 'column vector'
# or if you don't want to type so many brackets:
b = np.array([[1,2,3]]).T

JSON for List of int

Assuming your ints are 0, 375, 668,5 and 6:

    "Id": "610",
    "Name": "15",
    "Description": "1.99",
    "ItemModList": [

I suggest that you change "Id": "610" to "Id": 610 since it is a integer/long and not a string. You can read more about the JSON format and examples here

Detecting endianness programmatically in a C++ program

As stated above, use union tricks.

There are few problems with the ones advised above though, most notably that unaligned memory access is notoriously slow for most architectures, and some compilers won't even recognize such constant predicates at all, unless word aligned.

Because mere endian test is boring, here goes (template) function which will flip the input/output of arbitrary integer according to your spec, regardless of host architecture.

#include <stdint.h>

#define BIG_ENDIAN 1

template <typename T>
T endian(T w, uint32_t endian)
    // this gets optimized out into if (endian == host_endian) return w;
    union { uint64_t quad; uint32_t islittle; } t;
    t.quad = 1;
    if (t.islittle ^ endian) return w;
    T r = 0;

    // decent compilers will unroll this (gcc)
    // or even convert straight into single bswap (clang)
    for (int i = 0; i < sizeof(r); i++) {
        r <<= 8;
        r |= w & 0xff;
        w >>= 8;
    return r;


To convert from given endian to host, use:

host = endian(source, endian_of_source)

To convert from host endian to given endian, use:

output = endian(hostsource, endian_you_want_to_output)

The resulting code is as fast as writing hand assembly on clang, on gcc it's tad slower (unrolled &,<<,>>,| for every byte) but still decent.

Accessing MP3 metadata with Python

Just additional information to you guys:

take a look at the section "MP3 stuff and Metadata editors" in the page of PythonInMusic.

What is hashCode used for? Is it unique?

After learning what it is all about, I thought to write a hopefully simpler explanation via analogy:

Summary: What is a hashcode?

  • It's a fingerprint. We can use this finger print to identify people of interest.

Read below for more details:

Think of a Hashcode as us trying to To Uniquely Identify Someone

I am a detective, on the look out for a criminal. Let us call him Mr Cruel. (He was a notorious murderer when I was a kid -- he broke into a house kidnapped and murdered a poor girl, dumped her body and he's still out on the loose - but that's a separate matter). Mr Cruel has certain peculiar characteristics that I can use to uniquely identify him amongst a sea of people. We have 25 million people in Australia. One of them is Mr Cruel. How can we find him?

Bad ways of Identifying Mr Cruel

Apparently Mr Cruel has blue eyes. That's not much help because almost half the population in Australia also has blue eyes.

Good ways of Identifying Mr Cruel

What else can i use? I know: I will use a fingerprint!


  • It is really really hard for two people to have the same finger print (not impossible, but extremely unlikely).
  • Mr Cruel's fingerprint will never change.
  • Every single part of Mr Cruel's entire being: his looks, hair colour, personality, eating habits etc must (ideally) be reflected in his fingerprint, such that if he has a brother (who is very similar but not the same) - then both should have different finger prints. I say "should" because we cannot guarantee 100% that two people in this world will have different fingerprints.
  • But we can always guarantee that Mr Cruel will always have the same finger print - and that his fingerprint will NEVER change.

The above characteristics generally make for good hash functions.

So what's the deal with 'Collisions'?

So imagine if I get a lead and I find someone matching Mr Cruel's fingerprints. Does this mean I have found Mr Cruel?

........perhaps! I must take a closer look. If i am using SHA256 (a hashing function) and I am looking in a small town with only 5 people - then there is a very good chance I found him! But if I am using MD5 (another famous hashing function) and checking for fingerprints in a town with +2^1000 people, then it is a fairly good possibility that two entirely different people might have the same fingerprint.

So what is the benefit of all this anyways?

The only real benefit of hashcodes is if you want to put something in a hash table - and with hash tables you'd want to find objects quickly - and that's where the hash code comes in. They allow you to find things in hash tables really quickly. It's a hack that massively improves performance, but at a small expense of accuracy.

So let's imagine we have a hash table filled with people - 25 million suspects in Australia. Mr Cruel is somewhere in there..... How can we find him really quickly? We need to sort through them all: to find a potential match, or to otherwise acquit potential suspects. You don't want to consider each person's unique characteristics because that would take too much time. What would you use instead? You'd use a hashcode! A hashcode can tell you if two people are different. Whether Joe Bloggs is NOT Mr Cruel. If the prints don't match then you know it's definitely NOT Mr Cruel. But, if the finger prints do match then depending on the hash function you used, chances are already fairly good you found your man. But it's not 100%. The only way you can be certain is to investigate further: (i) did he/she have an opportunity/motive, (ii) witnesses etc etc.

When you are using computers if two objects have the same hash code value, then you again need to investigate further whether they are truly equal. e.g. You'd have to check whether the objects have e.g. the same height, same weight etc, if the integers are the same, or if the customer_id is a match, and then come to the conclusion whether they are the same. this is typically done perhaps by implementing an IComparer or IEquality interfaces.

Key Summary

So basically a hashcode is a finger print.

Digital Fingerprint - Picture attribute to Pixabay - Freely available for use at:

  1. Two different people/objects can theoretically still have the same fingerprint. Or in other words. If you have two fingerprints that are the same.........then they need not both come from the same person/object.
  2. Buuuuuut, the same person/object will always return the same fingerprint.
  3. Which means that if two objects return different hash codes then you know for 100% certainty that those objects are different.

It takes a good 3 minutes to get your head around the above. Perhaps read it a few times till it makes sense. I hope this helps someone because it took a lot of grief for me to learn it all!

How do I check to see if my array includes an object?

This ...

horse = Horse.find(:first,:offset=>rand(Horse.count))
unless @suggested_horses.exists?(
   @suggested_horses<< horse

Should probably be this ...

horse = Horse.find(:first,:offset=>rand(Horse.count))
unless @suggested_horses.include?(horse)
   @suggested_horses<< horse

How to remove element from array in forEach loop?

Use Array.prototype.filter instead of forEach:

var pre = document.getElementById('out');

function log(result) {
  pre.appendChild(document.createTextNode(result + '\n'));

var review = ['a', 'b', 'c', 'b', 'a', 'e'];
review = review.filter(item => item !== 'a');

Checking if an Android application is running in the background

See the comment in the onActivityDestroyed function.

Works with SDK target version 14> :

import android.os.Bundle;
import android.util.Log;

public class AppLifecycleHandler implements Application.ActivityLifecycleCallbacks {

    public static int active = 0;

    public void onActivityStopped(Activity activity) {
        Log.i("Tracking Activity Stopped", activity.getLocalClassName());

    public void onActivityStarted(Activity activity) {
        Log.i("Tracking Activity Started", activity.getLocalClassName());

    public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
        Log.i("Tracking Activity SaveInstanceState", activity.getLocalClassName());

    public void onActivityResumed(Activity activity) {
        Log.i("Tracking Activity Resumed", activity.getLocalClassName());

    public void onActivityPaused(Activity activity) {
        Log.i("Tracking Activity Paused", activity.getLocalClassName());

    public void onActivityDestroyed(Activity activity) {
        Log.i("Tracking Activity Destroyed", activity.getLocalClassName());

        // if active var here ever becomes zero, the app is closed or in background
        if(active == 0){


    public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
        Log.i("Tracking Activity Created", activity.getLocalClassName());

AngularJS not detecting Access-Control-Allow-Origin header?

It can also happen when your parameters are wrong in the request. In my case I was working with a API that sent me the message

"No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. The response had HTTP status code 401."

when I send wrong username or password with the POST request to login.

How to set textColor of UILabel in Swift

The text field placeholder and the "is really" label is hard to see at night. So i change their color depending one what time of day it is.

Also make sure you connect the new IBOutlet isReallyLabel. To do so open Main.storybaord and control-drag from "Convert" view controller to the "is really" text field and select the isReallyLabel under Outlets.

WARNING: I have not tested to see if the application is open while the time of day swaps.

@IBOutlet var isReallyLabel: UILabel! _x000D_
override func viewWillAppear(animated: Bool) {_x000D_
 let calendar = NSCalendar.currentCalendar()_x000D_
 let hour = calendar.component(.Hour, fromDate: NSDate())_x000D_
 let lightColor = UIColor.init(red: 0.961, green: 0.957, blue: 0945, alpha: 1)_x000D_
 let darkColor = UIColor.init(red: 0.184, green: 0.184 , blue: 0.188, alpha: 1)_x000D_
 switch hour {_x000D_
 case 8...18:_x000D_
  isReallyLabel.textColor = UIColor.blackColor()_x000D_
  view.backgroundColor = lightColor_x000D_
  let string = NSAttributedString(string: "Value", attributes: [NSForegroundColorAttributeName: UIColor.whiteColor()])_x000D_
  textField.attributedPlaceholder = string_x000D_
  isReallyLabel.textColor = UIColor.whiteColor()_x000D_
  view.backgroundColor = darkColor_x000D_

Substitute multiple whitespace with single whitespace in Python

A simple possibility (if you'd rather avoid REs) is

' '.join(mystring.split())

The split and join perform the task you're explicitly asking about -- plus, they also do the extra one that you don't talk about but is seen in your example, removing trailing spaces;-).

C++ JSON Serialization

Try json_dto. It is header-only and easy to use.

Simple example:

struct message_t
  std::string m_from;
  std::string m_text;

  // Entry point for json_dto.
  template < typename JSON_IO >
  json_io( JSON_IO & io )
      & json_dto::mandatory( "from", m_from )
      & json_dto::mandatory( "text", m_text );

This will be convertable to and from JSON:

{ "from" : "json_dto", "text" : "Hello world!" }

How to find a parent with a known class in jQuery?

Pass a selector to the jQuery parents function:


EDIT Hmm, actually Slaks's answer is superior if you only want the closest ancestor that matches your selector.

grunt: command not found when running from terminal

My fix for this on Mountain Lion was: -

npm install -g grunt-cli 

Saw it on

Batch file to run a command in cmd within a directory

This question is 5 years old. I wonder why still nobody has found the /d switch to set the working folder:

start /d "c:\activiti-5.9\setup" cmd /k ant demo.start

What is the best way to conditionally apply attributes in AngularJS?

Just in case you need solution for Angular 2 then its simple, use property binding like below, e.g. you want to make input read only conditionally, then add in square braces the attrbute followed by = sign and expression.

<input [readonly]="mode=='VIEW'"> 

How to config routeProvider and locationProvider in angularJS?

The only issue I see are relative links and templates not being properly loaded because of this.

from the docs regarding HTML5 mode

Relative links

Be sure to check all relative links, images, scripts etc. You must either specify the url base in the head of your main html file (<base href="/my-base">) or you must use absolute urls (starting with /) everywhere because relative urls will be resolved to absolute urls using the initial absolute url of the document, which is often different from the root of the application.

In your case you can add a forward slash / in href attributes ($location.path does this automatically) and also to templateUrl when configuring routes. This avoids routes like and makes sure templates load properly.

Here's an example that works:

    <a href="/">Home</a> | 
    <a href="/another">another</a> | 
    <a href="/tags/1">tags/1</a>
<div ng-view></div>


app.config(function($locationProvider, $routeProvider) {
    .when('/', {
      templateUrl: '/partials/template1.html', 
      controller: 'ctrl1'
    .when('/tags/:tagId', {
      templateUrl: '/partials/template2.html', 
      controller:  'ctrl2'
    .when('/another', {
      templateUrl: '/partials/template1.html', 
      controller:  'ctrl1'
    .otherwise({ redirectTo: '/' });

If using Chrome you will need to run this from a server.

Iframe transparent background

Why not just load the frame off screen or hidden and then display it once it has finished loading. You could show a loading icon in its place to begin with to give the user immediate feedback that it's loading.

How to get selected path and name of the file opened with file dialog?

After searching different websites looking for a solution as to how to separate the full path from the file name once the full one-piece information has been obtained from the Open File Dialog, and seeing how "complex" the solutions given were for an Excel newcomer like me, I wondered if there could be a simpler solution. So I started to work on it on my own and I came to this possibility. (I have no idea if somebody got the same idea before. Being so simple, if somebody has, I excuse myself.)

Dim fPath As String
Dim fName As String
Dim fdString As String

fdString = (the OpenFileDialog.FileName)

'Get just the path by finding the last "\" in the string from the end of it
 fPath = Left(fdString, InStrRev(fdString, "\"))

'Get just the file name by finding the last "\" in the string from the end of it
 fName = Mid(fdString, InStrRev(fdString, "\") + 1)

'Just to check the result
 Msgbox "File path: " & vbLF & fPath & vbLF & vblF & "File name: " & vbLF & fName

AND THAT'S IT!!! Just give it a try, and let me know how it goes...

How to copy a file to a remote server in Python using SCP or SSH?

A very simple approach is the following:

import os
os.system('sshpass -p "password" scp user@host:/path/to/file ./')

No python library are required (only os), and it works, however using this method relies on another ssh client to be installed. This could result in undesired behavior if ran on another system.

How can I get the DateTime for the start of the week?

Putting it all together, with Globalization and allowing for specifying the first day of the week as part of the call we have

public static DateTime StartOfWeek ( this DateTime dt, DayOfWeek? firstDayOfWeek )
    DayOfWeek fdow;

    if ( firstDayOfWeek.HasValue  )
        fdow = firstDayOfWeek.Value;
        System.Globalization.CultureInfo ci = System.Threading.Thread.CurrentThread.CurrentCulture;
        fdow = ci.DateTimeFormat.FirstDayOfWeek;

    int diff = dt.DayOfWeek - fdow;

    if ( diff < 0 )
        diff += 7;

    return dt.AddDays( -1 * diff ).Date;


How to create a list of objects?

I have some hacky answers that are likely to be terrible... but I have very little experience at this point.

a way:

class myClass():
    myInstances = []
    def __init__(self, myStr01, myStr02):
        self.myStr01 = myStr01
        self.myStr02 = myStr02

myObj01 = myClass("Foo", "Bar")
myObj02 = myClass("FooBar",  "Baz")

for thisObj in myClass.myInstances:

A hack way to get this done:

import sys
class myClass():
    def __init__(self, myStr01, myStr02):
        self.myStr01 = myStr01
        self.myStr02 = myStr02

myObj01 = myClass("Foo", "Bar")
myObj02 = myClass("FooBar",  "Baz")

myInstances = []
myLocals = str(locals()).split("'")
thisStep = 0
for thisLocalsLine in myLocals:
    thisStep += 1
    if "myClass object at" in thisLocalsLine:
        print(myLocals[(thisStep - 2)])
        #myInstances.append(myLocals[(thisStep - 2)])
        myInstances.append(getattr(sys.modules[__name__], myLocals[(thisStep - 2)]))

for thisObj in myInstances:

Another more 'clever' hack:

import sys
class myClass():
    def __init__(self, myStr01, myStr02):
        self.myStr01 = myStr01
        self.myStr02 = myStr02

myInstances = []
myClasses = {
    "myObj01": ["Foo", "Bar"],
    "myObj02": ["FooBar",  "Baz"]

for thisClass in myClasses.keys():
    exec("%s = myClass('%s', '%s')" % (thisClass, myClasses[thisClass][0], myClasses[thisClass][1]))
    myInstances.append(getattr(sys.modules[__name__], thisClass))

for thisObj in myInstances:

What is a lambda (function)?

Just because I cant see a C++11 example here, I'll go ahead and post this nice example from here. After searching, it is the clearest language specific example that I could find.

Hello, Lambdas, version 1

template<typename F>

void Eval( const F& f ) {
void foo() {
        Eval( []{ printf("Hello, Lambdas\n"); } );

Hello, Lambdas, version 2:

void bar() {
    auto f = []{ printf("Hello, Lambdas\n"); };

Difference between [routerLink] and routerLink

Router Link

routerLink with brackets and none - simple explanation.

The difference between routerLink= and [routerLink] is mostly like relative and absolute path.

Similar to a href you may want to navigate to ./about.html or

When you use without brackets then you navigate relative and without params;

"jumping" from to

<a routerLink="client/{{ }}" .... rest the same

When you use routerLink with brackets then you execute app to navigate absolute and you can add params how is the puzzle of your new link

first of all it will not include the "jump" from dashboard/ to dashboard/client/client-id and bring you data of client/client-id which is more helpful for EDIT CLIENT

<a [routerLink]="['/client',]" ... rest the same

The absolute way or brackets routerLink require additional set up of you components and app.routing.module.ts

The code without error will "tell you more/what is the purpose of []" when you make the test. Just check this with or without []. Than you may experiments with selectors which - as mention above - helps with dynamics routing. Selectors

See whats the routerLink construct

How to change the foreign key referential action? (behavior)

You can do this in one query if you're willing to change its name:

ALTER TABLE table_name
  DROP FOREIGN KEY `fk_name`,
  ADD CONSTRAINT `fk_name2` FOREIGN KEY (`remote_id`)
    REFERENCES `other_table` (`id`)

This is useful to minimize downtime if you have a large table.

Got a NumberFormatException while trying to parse a text file for objects

I changed Scanner fin = new Scanner(file); to Scanner fin = new Scanner(new File(file)); and it works perfectly now. I didn't think the difference mattered but there you go.

How to send a POST request with BODY in swift

If you are using Alamofire v4.0+ then the accepted answer would look like this:

let parameters: [String: Any] = [
    "IdQuiz" : 102,
    "IdUser" : "iosclient",
    "User" : "iosclient",
    "List": [
            "IdQuestion" : 5,
            "IdProposition": 2,
            "Time" : 32
            "IdQuestion" : 4,
            "IdProposition": 3,
            "Time" : 9

Alamofire.request("", method: .post, parameters: parameters, encoding: JSONEncoding.default)
    .responseJSON { response in

'was not declared in this scope' error

You need to declare y and c outside the scope of the if/else statement. A variable is only valid inside the scope it is declared (and a scope is marked with { })

#include <iostream> 
using namespace std; 
//Using the Gaussian algorithm 
int dayofweek(int date, int month, int year ){ 
int d=date; 
int y, c;
if (month==1||month==2) 
int m=(month+9)%12+1; 
int product=(d+(2.6*m-0.2)+y+y/4+c/4-2*c); 
return product%7; 

int main(){ 
return 0; 

How to document Python code using Doxygen

This is documented on the doxygen website, but to summarize here:

You can use doxygen to document your Python code. You can either use the Python documentation string syntax:

"""@package docstring
Documentation for this module.

More details.

def func():
    """Documentation for a function.

    More details.

In which case the comments will be extracted by doxygen, but you won't be able to use any of the special doxygen commands.

Or you can (similar to C-style languages under doxygen) double up the comment marker (#) on the first line before the member:

## @package pyexample
#  Documentation for this module.
#  More details.

## Documentation for a function.
#  More details.
def func():

In that case, you can use the special doxygen commands. There's no particular Python output mode, but you can apparently improve the results by setting OPTMIZE_OUTPUT_JAVA to YES.

Honestly, I'm a little surprised at the difference - it seems like once doxygen can detect the comments in ## blocks or """ blocks, most of the work would be done and you'd be able to use the special commands in either case. Maybe they expect people using """ to adhere to more Pythonic documentation practices and that would interfere with the special doxygen commands?

Tests not running in Test Explorer

Had same issue after clean install of VS 2019. Tests are found but not run with "Unexpected error occurred". Fixed by setting up x64 instead of x86 which was selected by default.

enter image description here

<button> background image

Replace button #rock With #rock

No need for additional selector scope. You're using an id which is as specific as you can be.

JsBin example:

How to return an array from an AJAX call?

@Xeon06, nice but just as a fyi for those that read this thread and tried like me... when returning the array from php => json_encode($theArray). converts to a string which to me isn't easy to manipulate esp for soft js users like myself.

Inside js, you are trying to get the array values and/or keys of the array u r better off using JSON.parse as in var jsArray = JSON.parse(data) where data is return array from php. the json encoded string is converted to js object that can now be manipulated easily.

e.g. foo={one:1, two:2, three:3} - gotten after JSON.parse

for (key in foo){ console.log("foo["+ key +"]="+ foo[key]) } - prints to ur firebug console. voila!

get UTC timestamp in python with datetime

Naïve datetime versus aware datetime

Default datetime objects are said to be "naïve": they keep time information without the time zone information. Think about naïve datetime as a relative number (ie: +4) without a clear origin (in fact your origin will be common throughout your system boundary).

In contrast, think about aware datetime as absolute numbers (ie: 8) with a common origin for the whole world.

Without timezone information you cannot convert the "naive" datetime towards any non-naive time representation (where does +4 targets if we don't know from where to start ?). This is why you can't have a datetime.datetime.toutctimestamp() method. (cf:

To check if your datetime dt is naïve, check dt.tzinfo, if None, then it's naïve:        ## DANGER: returns naïve datetime pointing on local time
datetime(1970, 1, 1)  ## returns naïve datetime pointing on user given time

I have naïve datetimes, what can I do ?

You must make an assumption depending on your particular context: The question you must ask yourself is: was your datetime on UTC ? or was it local time ?

  • If you were using UTC (you are out of trouble):

    import calendar
    def dt2ts(dt):
        """Converts a datetime object to UTC timestamp
        naive datetime will be considered UTC.
        return calendar.timegm(dt.utctimetuple())
  • If you were NOT using UTC, welcome to hell.

    You have to make your datetime non-naïve prior to using the former function, by giving them back their intended timezone.

    You'll need the name of the timezone and the information about if DST was in effect when producing the target naïve datetime (the last info about DST is required for cornercases):

    import pytz     ## pip install pytz
    mytz = pytz.timezone('Europe/Amsterdam')             ## Set your timezone
    dt = mytz.normalize(mytz.localize(dt, is_dst=True))  ## Set is_dst accordingly

    Consequences of not providing is_dst:

    Not using is_dst will generate incorrect time (and UTC timestamp) if target datetime was produced while a backward DST was put in place (for instance changing DST time by removing one hour).

    Providing incorrect is_dst will of course generate incorrect time (and UTC timestamp) only on DST overlap or holes. And, when providing also incorrect time, occuring in "holes" (time that never existed due to forward shifting DST), is_dst will give an interpretation of how to consider this bogus time, and this is the only case where .normalize(..) will actually do something here, as it'll then translate it as an actual valid time (changing the datetime AND the DST object if required). Note that .normalize() is not required for having a correct UTC timestamp at the end, but is probably recommended if you dislike the idea of having bogus times in your variables, especially if you re-use this variable elsewhere.

    and AVOID USING THE FOLLOWING: (cf: Datetime Timezone conversion using pytz)

    dt = dt.replace(tzinfo=timezone('Europe/Amsterdam'))  ## BAD !!

    Why? because .replace() replaces blindly the tzinfo without taking into account the target time and will choose a bad DST object. Whereas .localize() uses the target time and your is_dst hint to select the right DST object.

OLD incorrect answer (thanks @J.F.Sebastien for bringing this up):

Hopefully, it is quite easy to guess the timezone (your local origin) when you create your naive datetime object as it is related to the system configuration that you would hopefully NOT change between the naive datetime object creation and the moment when you want to get the UTC timestamp. This trick can be used to give an imperfect question.

By using time.mktime we can create an utc_mktime:

def utc_mktime(utc_tuple):
    """Returns number of seconds elapsed since epoch

    Note that no timezone are taken into consideration.

    utc tuple must be: (year, month, day, hour, minute, second)


    if len(utc_tuple) == 6:
        utc_tuple += (0, 0, 0)
    return time.mktime(utc_tuple) - time.mktime((1970, 1, 1, 0, 0, 0, 0, 0, 0))

def datetime_to_timestamp(dt):
    """Converts a datetime object to UTC timestamp"""

    return int(utc_mktime(dt.timetuple()))

You must make sure that your datetime object is created on the same timezone than the one that has created your datetime.

This last solution is incorrect because it makes the assumption that the UTC offset from now is the same than the UTC offset from EPOCH. Which is not the case for a lot of timezones (in specific moment of the year for the Daylight Saving Time (DST) offsets).

Figure out size of UILabel based on String in Swift

@IBOutlet weak var constraintTxtV: NSLayoutConstraint!
func TextViewDynamicallyIncreaseSize() {
    let contentSize = self.txtVDetails.sizeThatFits(self.txtVDetails.bounds.size)
    let higntcons = contentSize.height
    constraintTxtV.constant = higntcons

Control cannot fall through from one case label

You need to add a break statement:

switch (searchType)
case "SearchBooks":
    Selenium.Type("//*[@id='SearchBooks_TextInput']", searchText);
case "SearchAuthors":
    Selenium.Type("//*[@id='SearchAuthors_TextInput']", searchText);

This assumes that you want to either handle the SearchBooks case or the SearchAuthors - as you had written in, in a traditional C-style switch statement the control flow would have "fallen through" from one case statement to the next meaning that all 4 lines of code get executed in the case where searchType == "SearchBooks".

The compiler error you are seeing was introduced (at least in part) to warn the programmer of this potential error.

As an alternative you could have thrown an error or returned from a method.

Non-static variable cannot be referenced from a static context

Before you call an instance method or instance variable It needs a object(Instance). When instance variable is called from static method compiler doesn't know which is the object this variable belongs to. Because static methods doesn't have an object (Only one copy always). When you call an instance variable or instance methods from instance method it refer the this object. It means the variable belongs to whatever object created and each object have it's own copy of instance methods and variables.

Static variables are marked as static and instance variables doesn't have specific keyword.

"Unknown class <MyClass> in Interface Builder file" error at runtime

This problem happened to me when I added a picker view and then removed it. In case it will help someone, here's how I solved it finally:

  1. Open Document Outline at XCODE (don't know what is Document Outline? I didn't also - google it.. :) ).

  2. Find the Scene that makes the warning message appear, in the document outline window.

  3. On the problematic scene, stand (click) on View, and then in the Utility (google it) window select the Identity inspector tab and change back the custom class name to default UIView.

That't it. :)

jQuery.ajax handling continue responses: "success:" vs ".done"?

From JQuery Documentation

The jqXHR objects returned by $.ajax() as of jQuery 1.5 implement the Promise interface, giving them all the properties, methods, and behavior of a Promise (see Deferred object for more information). These methods take one or more function arguments that are called when the $.ajax() request terminates. This allows you to assign multiple callbacks on a single request, and even to assign callbacks after the request may have completed. (If the request is already complete, the callback is fired immediately.) Available Promise methods of the jqXHR object include:

jqXHR.done(function( data, textStatus, jqXHR ) {});

An alternative construct to the success callback option, refer to deferred.done() for implementation details. jqXHR, textStatus, errorThrown ) {});

An alternative construct to the error callback option, the .fail() method replaces the deprecated .error() method. Refer to for implementation details.

jqXHR.always(function( data|jqXHR, textStatus, jqXHR|errorThrown ) { }); 

(added in jQuery 1.6) An alternative construct to the complete callback option, the .always() method replaces the deprecated .complete() method.

In response to a successful request, the function's arguments are the same as those of .done(): data, textStatus, and the jqXHR object. For failed requests the arguments are the same as those of .fail(): the jqXHR object, textStatus, and errorThrown. Refer to deferred.always() for implementation details.

jqXHR.then(function( data, textStatus, jqXHR ) {}, function( jqXHR, textStatus, errorThrown ) {});

Incorporates the functionality of the .done() and .fail() methods, allowing (as of jQuery 1.8) the underlying Promise to be manipulated. Refer to deferred.then() for implementation details.

Deprecation Notice: The jqXHR.success(), jqXHR.error(), and jqXHR.complete() callbacks are removed as of jQuery 3.0. You can use jqXHR.done(),, and jqXHR.always() instead.

Entity Framework 5 Updating a Record

I have added an extra update method onto my repository base class that's similar to the update method generated by Scaffolding. Instead of setting the entire object to "modified", it sets a set of individual properties. (T is a class generic parameter.)

public void Update(T obj, params Expression<Func<T, object>>[] propertiesToUpdate)

    foreach (var p in propertiesToUpdate)
        Context.Entry(obj).Property(p).IsModified = true;

And then to call, for example:

public void UpdatePasswordAndEmail(long userId, string password, string email)
    var user = new User {UserId = userId, Password = password, Email = email};

    Update(user, u => u.Password, u => u.Email);


I like one trip to the database. Its probably better to do this with view models, though, in order to avoid repeating sets of properties. I haven't done that yet because I don't know how to avoid bringing the validation messages on my view model validators into my domain project.

Cannot get to $rootScope

You can not ask for instance during configuration phase - you can ask only for providers.

var app = angular.module('modx', []);

// configure stuff
app.config(function($routeProvider, $locationProvider) {
  // you can inject any provider here

// run blocks$rootScope) {
  // you can inject any instance here

See for more info.

Is it possible to hide/encode/encrypt php source code and let others have the system?

There are some online services for obfuscate php to hide the code from others. This is one Right Coder's Free Obfuscator Online

@Glavic is right. "Nothing is bulletproof". You can encode your source code and hide from bigger programmers, not from experts.

NSPhotoLibraryUsageDescription key must be present in Info.plist to use camera roll

If you added the key-string pairs in Info.plist (see Murat's answer above ) and still getting the error, try to check if the target you're currently working on has the keys.

In my case I had 2 targets (dev and development). I added the keys in the editor, but it only works for the main target and I was testing on development target. So I had to open XCode, click on the project > Info > Add the key-pair for the development target there.

Passing dynamic javascript values using Url.action()

This answer might not be 100% relevant to the question. But it does address the problem. I found this simple way of achieving this requirement. Code goes below:

<a href="@Url.Action("Display", "Customer")?custId={{cust.Id}}"></a>

In the above example {{cust.Id}} is an AngularJS variable. However one can replace it with a JavaScript variable.

I haven't tried passing multiple variables using this method but I'm hopeful that also can be appended to the Url if required.

JavaScript associative array to JSON

I posted a fix for this here

You can use this function to modify JSON.stringify to encode arrays, just post it near the beginning of your script (check the link above for more detail):

// Upgrade for JSON.stringify, updated to allow arrays
    // Convert array to object
    var convArrToObj = function(array){
        var thisEleObj = new Object();
        if(typeof array == "object"){
            for(var i in array){
                var thisEle = convArrToObj(array[i]);
                thisEleObj[i] = thisEle;
        }else {
            thisEleObj = array;
        return thisEleObj;
    var oldJSONStringify = JSON.stringify;
    JSON.stringify = function(input){
        if(oldJSONStringify(input) == '[]')
            return oldJSONStringify(convArrToObj(input));
            return oldJSONStringify(input);

Cannot send a content-body with this verb-type

I had the similar issue using Flurl.Http:

Flurl.Http.FlurlHttpException: Call failed. Cannot send a content-body with this verb-type. GET http://******:8301/api/v1/agents/**** ---> System.Net.ProtocolViolationException: Cannot send a content-body with this verb-type.

The problem was I used .WithHeader("Content-Type", "application/json") when creating IFlurlRequest.

How to convert date to string and to date again?

try this:

 String DATE_FORMAT_NOW = "yyyy-MM-dd";
 Date date = new Date();
 SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT_NOW);
 String stringDate = sdf.format(date );
    try {
        Date date2 = sdf.parse(stringDate);
    } catch(ParseException e){
     //Exception handling
    } catch(Exception e){
     //handle exception

Android: How can I pass parameters to AsyncTask's onPreExecute()?

You can either pass the parameter in the task constructor or when you call execute:

AsyncTask<Object, Void, MyTaskResult>

The first parameter (Object) is passed in doInBackground. The third parameter (MyTaskResult) is returned by doInBackground. You can change them to the types you want. The three dots mean that zero or more objects (or an array of them) may be passed as the argument(s).

public class MyActivity extends AppCompatActivity {

    TextView textView1;
    TextView textView2;

    protected void onCreate(Bundle savedInstanceState) {
        textView1 = (TextView) findViewById(;
        textView2 = (TextView) findViewById(;

        String input1 = "test";
        boolean input2 = true;
        int input3 = 100;
        long input4 = 100000000;

        new MyTask(input3, input4).execute(input1, input2);

    private class MyTaskResult {
        String text1;
        String text2;

    private class MyTask extends AsyncTask<Object, Void, MyTaskResult> {
        private String val1;
        private boolean val2;
        private int val3;
        private long val4;

        public MyTask(int in3, long in4) {
            this.val3 = in3;
            this.val4 = in4;

            // Do something ...

        protected void onPreExecute() {
            // Do something ...

        protected MyTaskResult doInBackground(Object... params) {
            MyTaskResult res = new MyTaskResult();
            val1 = (String) params[0];
            val2 = (boolean) params[1];

            //Do some lengthy operation    
            res.text1 = RunProc1(val1);
            res.text2 = RunProc2(val2);

            return res;

        protected void onPostExecute(MyTaskResult res) {



Escaping quotes and double quotes

Using the backtick (`) works fine for me if I put them in the following places:

$cmd="\\server\toto.exe -batch=B -param=`"sort1;parmtxt='Security ID=1234'`""

$cmd returns as:

\\server\toto.exe -batch=B -param="sort1;parmtxt='Security ID=1234'"

Is that what you were looking for?

The error PowerShell gave me referred to an unexpected token 'sort1', and that's how I determined where to put the backticks.

The @' ... '@ syntax is called a "here string" and will return exactly what is entered. You can also use them to populate variables in the following fashion:

"\\server\toto.exe -batch=B -param="sort1;parmtxt='Security ID=1234'""

The opening and closing symbols must be on their own line as shown above.

Visual studio equivalent of java System.out

Try: Console.WriteLine (type out for a Visual Studio snippet)


Another way is to use System.Diagnostics.Debug.WriteLine:


Debug.WriteLine may suit better for Output window in IDE because it will be rendered for both Console and Windows applications. Whereas Console.WriteLine won't be rendered in Output window but only in the Console itself in case of Console Application type.

Another difference is that Debug.WriteLine will not print anything in Release configuration.

How to put labels over geom_bar for each bar in R with ggplot2

To add to rcs' answer, if you want to use position_dodge() with geom_bar() when x is a POSIX.ct date, you must multiply the width by 86400, e.g.,

ggplot(data=dat, aes(x=Types, y=Number, fill=sample)) + 
 geom_bar(position = "dodge", stat = 'identity') +
 geom_text(aes(label=Number), position=position_dodge(width=0.9*86400), vjust=-0.25)

How do I start Mongo DB from Windows?

I have installed MongoDB in D:\Installs folder instead of default location.

Open command prompt and change directory into D:\Installs\MongoDB\Server\4.4\bin and run the following command:

mongod.exe --config=mongod.cfg

This should start the MongoDB service.

Now, Open MongoDB Compass and connect as shown below:

enter image description here

Please explain the exec() function and its family

Simplistically, in UNIX, you have the concept of processes and programs. A process is an environment in which a program executes.

The simple idea behind the UNIX "execution model" is that there are two operations you can do.

The first is to fork(), which creates a brand new process containing a duplicate (mostly) of the current program, including its state. There are a few differences between the two processes which allow them to figure out which is the parent and which is the child.

The second is to exec(), which replaces the program in the current process with a brand new program.

From those two simple operations, the entire UNIX execution model can be constructed.

To add some more detail to the above:

The use of fork() and exec() exemplifies the spirit of UNIX in that it provides a very simple way to start new processes.

The fork() call makes a near duplicate of the current process, identical in almost every way (not everything is copied over, for example, resource limits in some implementations, but the idea is to create as close a copy as possible). Only one process calls fork() but two processes return from that call - sounds bizarre but it's really quite elegant

The new process (called the child) gets a different process ID (PID) and has the PID of the old process (the parent) as its parent PID (PPID).

Because the two processes are now running exactly the same code, they need to be able to tell which is which - the return code of fork() provides this information - the child gets 0, the parent gets the PID of the child (if the fork() fails, no child is created and the parent gets an error code).

That way, the parent knows the PID of the child and can communicate with it, kill it, wait for it and so on (the child can always find its parent process with a call to getppid()).

The exec() call replaces the entire current contents of the process with a new program. It loads the program into the current process space and runs it from the entry point.

So, fork() and exec() are often used in sequence to get a new program running as a child of a current process. Shells typically do this whenever you try to run a program like find - the shell forks, then the child loads the find program into memory, setting up all command line arguments, standard I/O and so forth.

But they're not required to be used together. It's perfectly acceptable for a program to call fork() without a following exec() if, for example, the program contains both parent and child code (you need to be careful what you do, each implementation may have restrictions).

This was used quite a lot (and still is) for daemons which simply listen on a TCP port and fork a copy of themselves to process a specific request while the parent goes back to listening. For this situation, the program contains both the parent and the child code.

Similarly, programs that know they're finished and just want to run another program don't need to fork(), exec() and then wait()/waitpid() for the child. They can just load the child directly into their current process space with exec().

Some UNIX implementations have an optimized fork() which uses what they call copy-on-write. This is a trick to delay the copying of the process space in fork() until the program attempts to change something in that space. This is useful for those programs using only fork() and not exec() in that they don't have to copy an entire process space. Under Linux, fork() only makes a copy of the page tables and a new task structure, exec() will do the grunt work of "separating" the memory of the two processes.

If the exec is called following fork (and this is what happens mostly), that causes a write to the process space and it is then copied for the child process, before modifications are allowed.

Linux also has a vfork(), even more optimised, which shares just about everything between the two processes. Because of that, there are certain restrictions in what the child can do, and the parent halts until the child calls exec() or _exit().

The parent has to be stopped (and the child is not permitted to return from the current function) since the two processes even share the same stack. This is slightly more efficient for the classic use case of fork() followed immediately by exec().

Note that there is a whole family of exec calls (execl, execle, execve and so on) but exec in context here means any of them.

The following diagram illustrates the typical fork/exec operation where the bash shell is used to list a directory with the ls command:

| pid=7  |
| ppid=4 |
| bash   |
    | calls fork
+--------+             +--------+
| pid=7  |    forks    | pid=22 |
| ppid=4 | ----------> | ppid=7 |
| bash   |             | bash   |
+--------+             +--------+
    |                      |
    | waits for pid 22     | calls exec to run ls
    |                      V
    |                  +--------+
    |                  | pid=22 |
    |                  | ppid=7 |
    |                  | ls     |
    V                  +--------+
+--------+                 |
| pid=7  |                 | exits
| ppid=4 | <---------------+
| bash   |
    | continues

How to convert Blob to String and String to Blob in java

try this (a2 is BLOB col)

PreparedStatement ps1 = conn.prepareStatement("update t1 set a2=? where id=1");
Blob blob = conn.createBlob();
blob.setBytes(1, str.getBytes());
ps1.setBlob(1, blob);

it may work even without BLOB, driver will transform types automatically:

   ps1.setBytes(1, str.getBytes);
   ps1.setString(1, str);

Besides if you work with text CLOB seems to be a more natural col type

Python, how to read bytes from file and save it?

with open("input", "rb") as input:
    with open("output", "wb") as output:
        while True:
            data =
            if data == "":

The above will read 1 kilobyte at a time, and write it. You can support incredibly large files this way, as you won't need to read the entire file into memory.

Send text to specific contact programmatically (whatsapp)

 private void openWhatsApp() {
       //without '+'
        try {
            Intent sendIntent = new Intent("android.intent.action.MAIN");

            //sendIntent.setComponent(new ComponentName("com.whatsapp", "com.whatsapp.Conversation"));
        } catch(Exception e) {
            Toast.makeText(this, "Error/n" + e.toString(), Toast.LENGTH_SHORT).show();
            Log.e("Error",e+"")    ;    }

How do I create a Bash alias?

create a bash_profile at your user root - ex


open file

vim ~/.bash_profile

add alias as ex. (save and exit)

alias mydir="cd ~/Documents/dirname/anotherdir"

in new terminal just type mydir - it should open


How to generate List<String> from SQL query?

If you would like to query all columns

List<Users> list_users = new List<Users>();
MySqlConnection cn = new MySqlConnection("connection");
MySqlCommand cm = new MySqlCommand("select * from users",cn);
    MySqlDataReader dr = cm.ExecuteReader();
    while (dr.Read())
        list_users.Add(new Users(dr));
catch { /* error */ }
finally { cn.Close(); }

The User's constructor would do all the "dr.GetString(i)"

How do I add a library path in cmake?

The simplest way of doing this would be to add


add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # is found in ${CMAKE_SOURCE_DIR}/lib

The modern CMake version that doesn't add the -I and -L flags to every compiler invocation would be to use imported libraries:

add_library(bar SHARED IMPORTED) # or STATIC instead of SHARED
set_target_properties(bar PROPERTIES

set(FOO_SRCS "foo.cpp")
add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # also adds the required include path

If setting the INTERFACE_INCLUDE_DIRECTORIES doesn't add the path, older versions of CMake also allow you to use target_include_directories(bar PUBLIC /path/to/include). However, this no longer works with CMake 3.6 or newer.

Android load from URL to Bitmap

very fast way , this method works very quickly:

private Bitmap getBitmap(String url) 
        File f=fileCache.getFile(url);

        //from SD cache
        Bitmap b = decodeFile(f);
            return b;

        //from web
        try {
            Bitmap bitmap=null;
            URL imageUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
            InputStream is=conn.getInputStream();
            OutputStream os = new FileOutputStream(f);
            Utils.CopyStream(is, os);
            bitmap = decodeFile(f);
            return bitmap;
        } catch (Exception ex){
           return null;

    //decodes image and scales it to reduce memory consumption
    private Bitmap decodeFile(File f){
        try {
            //decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(new FileInputStream(f),null,o);

            //Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE=70;
            int width_tmp=o.outWidth, height_tmp=o.outHeight;
            int scale=1;
                if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)

            //decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
        } catch (FileNotFoundException e) {}
        return null;

How to create an instance of System.IO.Stream stream

Stream is a base class, you need to create one of the specific types of streams, such as MemoryStream.

Is it possible to use jQuery .on and hover?

None of these solutions worked for me when mousing over/out of objects created after the document has loaded as the question requests. I know this question is old but I have a solution for those still looking:

$("#container").on('mouseenter', '.selector', function() {
    //do something
$("#container").on('mouseleave', '.selector', function() {
    //do something

This will bind the functions to the selector so that objects with this selector made after the document is ready will still be able to call it.

Converting java date to Sql timestamp

I suggest using DateUtils from apache.commons library.

long millis = DateUtils.truncate(utilDate, Calendar.MILLISECOND).getTime();
java.sql.Timestamp sq = new java.sql.Timestamp(millis );

Edit: Fixed Calendar.MILISECOND to Calendar.MILLISECOND

Error: free(): invalid next size (fast):

I encountered a similar error. It was a noob mistake done in a hurry. Integer array without declaring size int a[] then trying to access it. C++ compiler should've caught such an error easily if it were in main. However since this particular int array was declared inside an object, it was being created at the same time as my object (many objects were being created) and the compiler was throwing a free(): invalid next size(normal) error. I thought of 2 explanations for this (please enlighten me if anyone knows more): 1.) This resulted in some random memory being assigned to it but since this wasn't accessible it was freeing up all the other heap memory just trying to find this int. 2.) The memory required by it was practically infinite for a program and to assign this it was freeing up all other memory.

A simple:

    int* a;
    class foo{ 
           a=new int[i];

Solved the problem. But it did take a lot of time trying to debug this because the compiler could not "really" find the error.

Namenode not getting started

For me the following worked after I changed the directory of the namenode and datanode in hdfs-site.xml

-- before executing the following steps stop all services with or in my case I used the to stop the dfs

  1. On the new configured directory, for every node (namenode and datanode), delete every folder/files inside it (in my case a 'current' directory).
  2. delete the Hadoop temporary directory: $rm -rf /tmp/haddop-$USER
  3. format the Namenode: hadoop/bin/hdfs namenode -format

After I followed those steps my namenode and datanodes were alive using the new configured directory.

How to set timeout for a line of c# code

You can use the Task Parallel Library. To be more exact, you can use Task.Wait(TimeSpan):

using System.Threading.Tasks;

var task = Task.Run(() => SomeMethod(input));
if (task.Wait(TimeSpan.FromSeconds(10)))
    return task.Result;
    throw new Exception("Timed out");

Nested ng-repeat

It's better to have a proper JSON format instead of directly using the one converted from XML.

    "number": "2013-W45",
    "days": [
        "dow": "1",
        "templateDay": "Monday",
        "jobs": [
            "name": "Wakeup",
            "jobs": [
                "name": "prepare breakfast",

            "name": "work 9-5",

        "dow": "2",
        "templateDay": "Tuesday",
        "jobs": [
            "name": "Wakeup",
            "jobs": [
                "name": "prepare breakfast",


This will make things much easier and easy to loop through.

Now you can write the loop as -

<div ng-repeat="week in myData">
   <div ng-repeat="day in week.days">
      {{day.dow}} - {{day.templateDay}}
         <li ng-repeat="job in"> 

How to get all checked checkboxes

In IE9+, Chrome or Firefox you can do:

var checkedBoxes = document.querySelectorAll('input[name=mycheckboxes]:checked');

Multiplication on command line terminal

For more advanced and precise math consider using bc(1).

echo "3 * 2.19" | bc -l 

Django: List field in model?

You can flatten the list and then store the values to a CommaSeparatedIntegerField. When you read back from the database, just group the values back into threes.

Disclaimer: according to database normalization theory, it is better not to store collections in single fields; instead you would be encouraged to store the values in those triplets in their own fields and link them via foreign keys. In the real world, though, sometimes that is too cumbersome/slow.

Checking if a website is up via Python

I think the easiest way to do it is by using Requests module.

import requests

def url_ok(url):
    r = requests.head(url)
    return r.status_code == 200

Using the slash character in Git branch name

It is possible to have hierarchical branch names (branch names with slash). For example in my repository I have such branch(es). One caveat is that you can't have both branch 'foo' and branch 'foo/bar' in repository.

Your problem is not with creating branch with slash in name.

$ git branch foo/bar
error: unable to resolve reference refs/heads/labs/feature: Not a directory
fatal: Failed to lock ref for update: Not a directory

The above error message talks about 'labs/feature' branch, not 'foo/bar' (unless it is a mistake in copy'n'paste, i.e you edited parts of session). What is the result of git branch or git rev-parse --symbolic-full-name HEAD?

How to make a smaller RatingBar?

Just use:


Change the scale factor according to your need.

In order to scale without creating a padding on the left also add


CertificateException: No name matching found

In case, it helps someone:

Use case: i am using a self-signed certificate for my development on localhost.

Error: Caused by: No name matching localhost found

Solution: When you generate your self-signed certicate, make sure you answer this question like that(See Bruno's answer for the why):

What is your first and last name?
  [Unknown]:  localhost

As a bonus, here are my steps:
1. Generate self-signed certificate:

keytool -genkeypair -alias netty -storetype PKCS12 -keyalg RSA -keysize 2048 -keystore keystore.p12 -validity 4000
Enter keystore password: ***
Re-enter new password: ***
What is your first and last name?
  [Unknown]:  localhost

2. Copy the certificate in src/main/resources(if necessary)

3. Update the cacerts
keytool -v -importkeystore -srckeystore keystore.p12 -srcstoretype pkcs12 -destkeystore "%JAVA_HOME%\jre\lib\security\cacerts" -deststoretype jks

4. Update your config(in my case



Can I start the iPhone simulator without "Build and Run"?

Since XCode 4.3 the location has changed, the simulator can now be found at:


Enable ASP.NET ASMX web service for HTTP POST / GET requests

Try to declare UseHttpGet over your method.

[ScriptMethod(UseHttpGet = true)]
public string HelloWorld()
    return "Hello World";

convert double to int

You can use a cast if you want the default truncate-towards-zero behaviour. Alternatively, you might want to use Math.Ceiling, Math.Round, Math.Floor etc - although you'll still need a cast afterwards.

Don't forget that the range of int is much smaller than the range of double. A cast from double to int won't throw an exception if the value is outside the range of int in an unchecked context, whereas a call to Convert.ToInt32(double) will. The result of the cast (in an unchecked context) is explicitly undefined if the value is outside the range.

Error 0x80005000 and DirectoryServices

Just FYI, I had the same error and was using the correct credentials but my LDAP url was wrong :(

I got the exact same error message and code

How do I create an empty array/matrix in NumPy?

I think you want to handle most of the work with lists then use the result as a matrix. Maybe this is a way ;

ur_list = []
for col in columns:

mat = np.matrix(ur_list)

How to send an object from one Android Activity to another using Intents?

Start another activity from this activity pass parameters via Bundle Object

Intent intent = new Intent(getBaseContext(), YourActivity.class);
intent.putExtra("USER_NAME", "[email protected]");

Retrieve on another activity (YourActivity)

String s = getIntent().getStringExtra("USER_NAME");

This is ok for simple kind data type. But if u want to pass complex data in between activity u need to serialize it first.

Here we have Employee Model

class Employee{
    private String empId;
    private int age;
    print Double salary;


You can use Gson lib provided by google to serialize the complex data like this

String strEmp = new Gson().toJson(emp);
Intent intent = new Intent(getBaseContext(), YourActivity.class);
intent.putExtra("EMP", strEmp);

Bundle bundle = getIntent().getExtras();
    String empStr = bundle.getString("EMP");
            Gson gson = new Gson();
            Type type = new TypeToken<Employee>() {
            Employee selectedEmp = gson.fromJson(empStr, type);

How to pass arguments to entrypoint in docker-compose.yml

The command clause does work as @Karthik says above.

As a simple example, the following service will have a -inMemory added to its ENTRYPOINT when docker-compose up is run.

version: '2'
    build: local-dynamo
    image: spud/dynamo
    command: -inMemory

Why does JSON.parse fail with the empty string?

As an empty string is not valid JSON it would be incorrect for JSON.parse('') to return null because "null" is valid JSON. e.g.


returns null. It would be a mistake for invalid JSON to also be parsed to null.

While an empty string is not valid JSON two quotes is valid JSON. This is an important distinction.

Which is to say a string that contains two quotes is not the same thing as an empty string.


will parse correctly, (returning an empty string). But


will not.

Valid minimal JSON strings are

The empty object '{}'

The empty array '[]'

The string that is empty '""'

A number e.g. '123.4'

The boolean value true 'true'

The boolean value false 'false'

The null value 'null'

How can I extract a predetermined range of lines from a text file on Unix?

Using ed:

ed -s infile <<<'16224,16482p'

-s suppresses diagnostic output; the actual commands are in a here-string. Specifically, 16224,16482p runs the p (print) command on the desired line address range.

log4j configuration via JVM argument(s)?

Do you have a log4j configuration file ? Just reference it using

-Dlog4j.configuration={path to file}

where {path to file} should be prefixed with file:

Edit: If you are working with log4j2, you need to use

-Dlog4j.configurationFile={path to file}

Taken from answer

ExpressJS How to structure an application?

It's been quite a while since the last answer to this question and Express has also recently released version 4, which added a few useful things for organising your app structure.

Below is a long up to date blog post about best practices on how to structure your Express app.

There is also a GitHub repository applying the advice in the article. It is always up to date with the latest Express version.

JavaScript push to array

object["property"] = value;

or = value;

Object and Array in JavaScript are different in terms of usage. Its best if you understand them:

Object vs Array: JavaScript

What are "res" and "req" parameters in Express functions?

req is an object containing information about the HTTP request that raised the event. In response to req, you use res to send back the desired HTTP response.

Those parameters can be named anything. You could change that code to this if it's more clear:

app.get('/user/:id', function(request, response){
  response.send('user ' +;


Say you have this method:

app.get('/people.json', function(request, response) { });

The request will be an object with properties like these (just to name a few):

  • request.url, which will be "/people.json" when this particular action is triggered
  • request.method, which will be "GET" in this case, hence the app.get() call.
  • An array of HTTP headers in request.headers, containing items like request.headers.accept, which you can use to determine what kind of browser made the request, what sort of responses it can handle, whether or not it's able to understand HTTP compression, etc.
  • An array of query string parameters if there were any, in request.query (e.g. /people.json?foo=bar would result in containing the string "bar").

To respond to that request, you use the response object to build your response. To expand on the people.json example:

app.get('/people.json', function(request, response) {
  // We want to set the content-type header so that the browser understands
  //  the content of the response.

  // Normally, the data is fetched from a database, but we can cheat:
  var people = [
    { name: 'Dave', location: 'Atlanta' },
    { name: 'Santa Claus', location: 'North Pole' },
    { name: 'Man in the Moon', location: 'The Moon' }

  // Since the request is for a JSON representation of the people, we
  //  should JSON serialize them. The built-in JSON.stringify() function
  //  does that.
  var peopleJSON = JSON.stringify(people);

  // Now, we can use the response object's send method to push that string
  //  of people JSON back to the browser in response to this request:

Passing parameters from jsp to Spring Controller method

Your controller method should be like this:

@RequestMapping(value = " /<your mapping>/{id}", method=RequestMethod.GET)
public String listNotes(@PathVariable("id")int id,Model model) {
    Person person = personService.getCurrentlyAuthenticatedUser();
    int id = 2323;  // Currently passing static values for testing
    model.addAttribute("person", new Person());
    model.addAttribute("listPersons", this.personService.listPersons());
    return "note";

Use the id in your code, call the controller method from your JSP as:

/{your mapping}/{your id}


Change your jsp code to:

<c:forEach items="${listNotes}" var="notices" varStatus="status">
        <td><a href="<c:url value='/editnote/${listNotes[status.index].noticesid}' />" >Edit</a></td>
        <td><a href="<c:url value='/removenote/${listNotes[status.index].noticesid}' />" >Delete</a></td>

Getting time difference between two times in PHP

$start = strtotime("12:00");
$end = // Run query to get datetime value from db
$elapsed = $end - $start;
echo date("H:i", $elapsed);

Bootstrap carousel width and height

just put height="400px" into image attribute like

<img class="d-block w-100" src="../assets/img/natural-backdrop.jpg" height="400px" alt="First slide">

Create a batch file to run an .exe with an additional parameter

You can use

start "" "%USERPROFILE%\Desktop\BGInfo\bginfo.exe" "%USERPROFILE%\Desktop\BGInfo\dc_bginfo.bgi"


start "" /D "%USERPROFILE%\Desktop\BGInfo" bginfo.exe dc_bginfo.bgi


"%USERPROFILE%\Desktop\BGInfo\bginfo.exe" "%USERPROFILE%\Desktop\BGInfo\dc_bginfo.bgi"


cd /D "%USERPROFILE%\Desktop\BGInfo"
bginfo.exe dc_bginfo.bgi

Help on commands start and cd is output by executing in a command prompt window help start or start /? and help cd or cd /?.

But I do not understand why you need a batch file at all for starting the application with the additional parameter. Create a shortcut (*.lnk) on your desktop for this application. Then right click on the shortcut, left click on Properties and append after a space character "%USERPROFILE%\Desktop\BGInfo\dc_bginfo.bgi" as parameter.

Clearing UIWebview cache

My educated guess is that the memory use you are seeing is not from the page content, but rather from loading UIWebView and all of it's supporting WebKit libraries. I love the UIWebView control, but it is a 'heavy' control that pulls in a very large block of code.

This code is a large sub-set of the iOS Safari browser, and likely initializes a large body of static structures.

Format Date as "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"

You can use javax.xml.bind.DatatypeConverter class

DatatypeConverter.printDateTime & DatatypeConverter.parseDateTime

changing the owner of folder in linux

Use chown to change ownership and chmod to change rights.

use the -R option to apply the rights for all files inside of a directory too.

Note that both these commands just work for directories too. The -R option makes them also change the permissions for all files and directories inside of the directory.

For example

sudo chown -R username:group directory

will change ownership (both user and group) of all files and directories inside of directory and directory itself.

sudo chown username:group directory

will only change the permission of the folder directory but will leave the files and folders inside the directory alone.

you need to use sudo to change the ownership from root to yourself.


Note that if you use chown user: file (Note the left-out group), it will use the default group for that user.

Also You can change the group ownership of a file or directory with the command:

chgrp group_name file/directory_name

You must be a member of the group to which you are changing ownership to.

You can find group of file as follows

# ls -l file
-rw-r--r-- 1 root family 0 2012-05-22 20:03 file

# chown sujit:friends file

User 500 is just a normal user. Typically user 500 was the first user on the system, recent changes (to /etc/login.defs) has altered the minimum user id to 1000 in many distributions, so typically 1000 is now the first (non root) user.

What you may be seeing is a system which has been upgraded from the old state to the new state and still has some processes knocking about on uid 500. You can likely change it by first checking if your distro should indeed now use 1000, and if so alter the login.defs file yourself, the renumber the user account in /etc/passwd and chown/chgrp all their files, usually in /home/, then reboot.

But in answer to your question, no, you should not really be worried about this in all likelihood. It'll be showing as "500" instead of a username because o user in /etc/passwd has a uid set of 500, that's all.

Also you can show your current numbers using id i'm willing to bet it comes back as 1000 for you.

Eclipse Optimize Imports to Include Static Imports

Shortcut for static import: CTRL + SHIFT + M

Multiple Buttons' OnClickListener() android

public class MainActivity extends AppCompatActivity implements OnClickListener  {
    Button  b1,b2;
    protected void onCreate(Bundle savedInstanceState)
        b1= (Button) findViewById(;
        b2= (Button) findViewById(;

    public void onClick(View v)
            Intent intent=new Intent(getApplicationContext(),SignIn.class);
        else if (v.getId()
            Intent in=new Intent(getApplicationContext(),SignUpactivity.class);

Filter rows which contain a certain string


It is possible to use str_detect of the stringr package included in the tidyverse package. str_detect returns True or False as to whether the specified vector contains some specific string. It is possible to filter using this boolean value. See Introduction to stringr for details about stringr package.

# - Attaching packages -------------------- tidyverse 1.2.1 -
# ? ggplot2 2.2.1     ? purrr   0.2.4
# ? tibble  1.4.2     ? dplyr   0.7.4
# ? tidyr   0.7.2     ? stringr 1.2.0
# ? readr   1.1.1     ? forcats 0.3.0
# - Conflicts --------------------- tidyverse_conflicts() -
# ? dplyr::filter() masks stats::filter()
# ? dplyr::lag()    masks stats::lag()

mtcars$type <- rownames(mtcars)
mtcars %>%
  filter(str_detect(type, 'Toyota|Mazda'))
# mpg cyl  disp  hp drat    wt  qsec vs am gear carb           type
# 1 21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4      Mazda RX4
# 2 21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4  Mazda RX4 Wag
# 3 33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1 Toyota Corolla
# 4 21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1  Toyota Corona

The good things about Stringr

We should use rather stringr::str_detect() than base::grepl(). This is because there are the following reasons.

  • The functions provided by the stringr package start with the prefix str_, which makes the code easier to read.
  • The first argument of the functions of stringr package is always the data.frame (or value), then comes the parameters.(Thank you Paolo)
object <- "stringr"
# The functions with the same prefix `str_`.
# The first argument is an object.
stringr::str_count(object) # -> 7
stringr::str_sub(object, 1, 3) # -> "str"
stringr::str_detect(object, "str") # -> TRUE
stringr::str_replace(object, "str", "") # -> "ingr"
# The function names without common points.
# The position of the argument of the object also does not match.
base::nchar(object) # -> 7
base::substr(object, 1, 3) # -> "str"
base::grepl("str", object) # -> TRUE
base::sub("str", "", object) # -> "ingr"


The results of the benchmark test are as follows. For large dataframe, str_detect is faster.


# The data. Data expo 09. ASA Statistics Computing and Graphics 
df <- read_csv("Downloads/2008.csv")
# [1] 7009728      29

  "str_detect" = {df %>% filter(str_detect(Dest, 'MCO|BWI'))},
  "grepl" = {df %>% filter(grepl('MCO|BWI', Dest))},
  replications = 10,
  columns = c("test", "replications", "elapsed", "relative", "user.self", "sys.self"))
# test replications elapsed relative user.self sys.self
# 2      grepl           10  16.480    1.513    16.195    0.248
# 1 str_detect           10  10.891    1.000     9.594    1.281

iPhone hide Navigation Bar only on first page

The currently accepted answer does not match the intended behavior described in the question. The question asks for the navigation bar to be hidden on the root view controller, but visible everywhere else, but the accepted answer hides the navigation bar on a particular view controller. What happens when another instance of the first view controller is pushed onto the stack? It will hide the navigation bar even though we are not looking at the root view controller.

Instead, @Chad M.'s strategy of using the UINavigationControllerDelegate is a good one, and here is a more complete solution. Steps:

  1. Subclass UINavigationController
  2. Implement the -navigationController:willShowViewController:animated method to show or hide the navigation bar based on whether it is showing the root view controller
  3. Override the initialization methods to set the UINavigationController subclass as its own delegate

Complete code for this solution can be found in this Gist. Here's the navigationController:willShowViewController:animated implementation:

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
    /* Hide navigation bar if root controller */
    if ([viewController isEqual:[self.viewControllers firstObject]]) {
        [self setNavigationBarHidden:YES animated:animated];
    } else {
        [self setNavigationBarHidden:NO animated:animated];

Golang append an item to a slice

In your example the slice argument of the Test function receives a copy of the variable a in the caller's scope.

Since a slice variable holds a "slice descriptor" which merely references an underlying array, in your Test function you modify the slice descriptor held in the slice variable several times in a row, but this does not affect the caller and its a variable.

Inside the Test function, the first append reallocates the backing array under the slice variable, copies its original contents over, appends 100 to it, and that's what you're observing. Upon exiting from Test, the slice variable goes out of scope and so does the (new) underlying array that slice references. (Jeff Lee is correct about that it's not what really happens, so the updated version follows; as he correctly states, this answer is correct, if maybe a bit too terse.)

Outside the Test function, a slice of length 7 and capacity 8 is allocated, and its 7 elements filled.
Inside the Test function, the first append sees the that the slice's capacity is still one element larger than its length — in other words, there is room for one more element to add without reallocation. So it "eats up" that remaining element and places 100 to it, after which it adjusts the length in the copy of the slice descriptor to become equal to the slice's capaticy. This does not affect the slice descriptor's in the caller's scope.

And that's what you're observing. Upon exiting from Test, the slice variable goes out of scope and so does the (new) underlying array that slice references.

If you want to make Test behave like append, you have to return the new slice from it — just like append does — and require the callers of Test to use it in the same way they would use append:

func Test(slice []int) []int {
    slice = append(slice, 100)


    return slice

a = Test(a)

Please read this article thoroughly as it basically shows you how to implement append by hand, after explaining how slices are working internally. Then read this.

Bootstrap 3 - How to load content in modal body via AJAX?

This is actually super simple with just a little bit of added javascript. The link's href is used as the ajax content source. Note that for Bootstrap 3.* we set data-remote="false" to disable the deprecated Bootstrap load function.


// Fill modal with content from link href
$("#myModal").on("", function(e) {
    var link = $(e.relatedTarget);

Html (based on the official example):

<!-- Link trigger modal -->
<a href="remoteContent.html" data-remote="false" data-toggle="modal" data-target="#myModal" class="btn btn-default">
    Launch Modal

<!-- Default bootstrap modal example -->
<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
        <h4 class="modal-title" id="myModalLabel">Modal title</h4>
      <div class="modal-body">
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>

Try it yourself:

How do I use the built in password reset/change views with my own templates

You can do the following:

  1. add to your urlpatterns (r'^/accounts/password/reset/$', password_reset)
  2. put your template in '/templates/registration/password_reset_form.html'
  3. make your app come before 'django.contrib.auth' in INSTALLED_APPS


When the templates are loaded, they are searched in your INSTALLED_APPS variable in . The order is dictated by the definition's rank in INSTALLED_APPS, so since your app come before 'django.contrib.auth' your template were loaded (reference:

Motivation of approach:

  1. I want be more dry and don't repeat for any view(defined by django) the template name (they are already defined in django)
  2. I want a smallest

What is "entropy and information gain"?

I really recommend you read about Information Theory, bayesian methods and MaxEnt. The place to start is this (freely available online) book by David Mackay:

Those inference methods are really far more general than just text mining and I can't really devise how one would learn how to apply this to NLP without learning some of the general basics contained in this book or other introductory books on Machine Learning and MaxEnt bayesian methods.

The connection between entropy and probability theory to information processing and storing is really, really deep. To give a taste of it, there's a theorem due to Shannon that states that the maximum amount of information you can pass without error through a noisy communication channel is equal to the entropy of the noise process. There's also a theorem that connects how much you can compress a piece of data to occupy the minimum possible memory in your computer to the entropy of the process that generated the data.

I don't think it's really necessary that you go learning about all those theorems on communication theory, but it's not possible to learn this without learning the basics about what is entropy, how it's calculated, what is it's relationship with information and inference, etc...

What is the best project structure for a Python application?

Non-python data is best bundled inside your Python modules using the package_data support in setuptools. One thing I strongly recommend is using namespace packages to create shared namespaces which multiple projects can use -- much like the Java convention of putting packages in com.yourcompany.yourproject (and being able to have a shared com.yourcompany.utils namespace).

Re branching and merging, if you use a good enough source control system it will handle merges even through renames; Bazaar is particularly good at this.

Contrary to some other answers here, I'm +1 on having a src directory top-level (with doc and test directories alongside). Specific conventions for documentation directory trees will vary depending on what you're using; Sphinx, for instance, has its own conventions which its quickstart tool supports.

Please, please leverage setuptools and pkg_resources; this makes it much easier for other projects to rely on specific versions of your code (and for multiple versions to be simultaneously installed with different non-code files, if you're using package_data).

Remove android default action bar

I've noticed that if you set the theme in the AndroidManifest, it seems to get rid of that short time where you can see the action bar. So, try adding this to your manifest:


Just add it to your application tag to apply it app-wide.

What is a Python egg?

Python eggs are a way of bundling additional information with a Python project, that allows the project's dependencies to be checked and satisfied at runtime, as well as allowing projects to provide plugins for other projects. There are several binary formats that embody eggs, but the most common is '.egg' zipfile format, because it's a convenient one for distributing projects. All of the formats support including package-specific data, project-wide metadata, C extensions, and Python code.

The easiest way to install and use Python eggs is to use the "Easy Install" Python package manager, which will find, download, build, and install eggs for you; all you do is tell it the name (and optionally, version) of the Python project(s) you want to use.

Python eggs can be used with Python 2.3 and up, and can be built using the setuptools package (see the Python Subversion sandbox for source code, or the EasyInstall page for current installation instructions).

The primary benefits of Python Eggs are:

  • They enable tools like the "Easy Install" Python package manager

  • .egg files are a "zero installation" format for a Python package; no build or install step is required, just put them on PYTHONPATH or sys.path and use them (may require the runtime installed if C extensions or data files are used)

  • They can include package metadata, such as the other eggs they depend on

  • They allow "namespace packages" (packages that just contain other packages) to be split into separate distributions (e.g. zope., twisted., peak.* packages can be distributed as separate eggs, unlike normal packages which must always be placed under the same parent directory. This allows what are now huge monolithic packages to be distributed as separate components.)

  • They allow applications or libraries to specify the needed version of a library, so that you can e.g. require("Twisted-Internet>=2.0") before doing an import twisted.internet.

  • They're a great format for distributing extensions or plugins to extensible applications and frameworks (such as Trac, which uses eggs for plugins as of 0.9b1), because the egg runtime provides simple APIs to locate eggs and find their advertised entry points (similar to Eclipse's "extension point" concept).

There are also other benefits that may come from having a standardized format, similar to the benefits of Java's "jar" format.

How to manually update datatables table with new JSON data

SOLUTION: (Notice: this solution is for datatables version 1.10.4 (at the moment) not legacy version).

CLARIFICATION Per the API documentation (1.10.15), the API can be accessed three ways:

  1. The modern definition of DataTables (upper camel case):

    var datatable = $( selector ).DataTable();

  2. The legacy definition of DataTables (lower camel case):

    var datatable = $( selector ).dataTable().api();

  3. Using the new syntax.

    var datatable = new $.fn.dataTable.Api( selector );

Then load the data like so:

$.get('myUrl', function(newDataArray) {

Use draw(false) to stay on the same page after the data update.

API references:

font size in html code

just write the css attributes in a proper manner i.e:


Resize background image in div using css

i would recommend using this:

  background-image: url(your file location here);
  background-size:cover;(will only work with css3)

hope it helps :D

And if this doesnt support your needs just say it: i can make a jquery for multibrowser support.

Working with huge files in VIM

emacs works very well with files into the 100's of megabytes, I've used it on log files without too much trouble.

But generally when I have some kind of analysis task, I find writing a perl script a better choice.

Code to loop through all records in MS Access

Found a good code with comments explaining each statement. Code found at - accessallinone

Sub DAOLooping()
On Error GoTo ErrorHandler

Dim strSQL As String
Dim rs As DAO.Recordset

strSQL = "tblTeachers"
'For the purposes of this post, we are simply going to make 
'strSQL equal to tblTeachers.
'You could use a full SELECT statement such as:
'SELECT * FROM tblTeachers (this would produce the same result in fact).
'You could also add a Where clause to filter which records are returned:
'SELECT * FROM tblTeachers Where ZIPPostal = '98052'
' (this would return 5 records)

Set rs = CurrentDb.OpenRecordset(strSQL)
'This line of code instantiates the recordset object!!! 
'In English, this means that we have opened up a recordset 
'and can access its values using the rs variable.

With rs

    If Not .BOF And Not .EOF Then
    'We don’t know if the recordset has any records, 
    'so we use this line of code to check. If there are no records 
    'we won’t execute any code in the if..end if statement.    

        'It is not necessary to move to the last record and then back 
        'to the first one but it is good practice to do so.

        While (Not .EOF)
        'With this code, we are using a while loop to loop 
        'through the records. If we reach the end of the recordset, .EOF 
        'will return true and we will exit the while loop.

            Debug.Print rs.Fields("teacherID") & " " & rs.Fields("FirstName")
            'prints info from fields to the immediate window

            'We need to ensure that we use .MoveNext, 
            'otherwise we will be stuck in a loop forever… 
            '(or at least until you press CTRL+Break)

    End If

    'Make sure you close the recordset...
End With

    Set rs = Nothing
    '..and set it to nothing
    Exit Sub
    Resume ExitSub
End Sub

Recordsets have two important properties when looping through data, EOF (End-Of-File) and BOF (Beginning-Of-File). Recordsets are like tables and when you loop through one, you are literally moving from record to record in sequence. As you move through the records the EOF property is set to false but after you try and go past the last record, the EOF property becomes true. This works the same in reverse for the BOF property.

These properties let us know when we have reached the limits of a recordset.

Failed to allocate memory: 8

What worked for me on Windows was:

1) Closing Eclipse 2) Running Avd UI 3) Closing all running processes, especially ones that are heavy in memory, like Chrome, explorer.exe, etc 4) Start the emulator 5) Win

What causes the error "undefined reference to (some function)"?

It's a linker error. ld is the linker, so if you get an error message ending with "ld returned 1 exit status", that tells you that it's a linker error.

The error message tells you that none of the object files you're linking against contains a definition for avergecolumns. The reason for that is that the function you've defined is called averagecolumns (in other words: you misspelled the function name when calling the function (and presumably in the header file as well - otherwise you'd have gotten a different error at compile time)).

Comparing two NumPy arrays for equality, element-wise

Now use np.array_equal. From documentation:

np.array_equal([1, 2], [1, 2])
np.array_equal(np.array([1, 2]), np.array([1, 2]))
np.array_equal([1, 2], [1, 2, 3])
np.array_equal([1, 2], [1, 4])

Laravel Migration table already exists, but I want to add new not the older

DANGER - most of these answers will wipe your database and is not recommended for production use.

It's clear there are a lot of "solutions" for this problem, but all these solutions I read through are very destructive solutions and none of them work for a production database. Based on the number of solutions, it also seems that there could be several causes to this error.

My error was being caused by a missing entry in my migrations table. I'm not sure exactly how it happened but by adding it back in I no longer received the error.

Call asynchronous method in constructor?

The best solution is to acknowledge the asynchronous nature of the download and design for it.

In other words, decide what your application should look like while the data is downloading. Have the page constructor set up that view, and start the download. When the download completes update the page to display the data.

I have a blog post on asynchronous constructors that you may find useful. Also, some MSDN articles; one on asynchronous data-binding (if you're using MVVM) and another on asynchronous best practices (i.e., you should avoid async void).

MySQL - Get row number on select

It's now builtin in MySQL 8.0 and MariaDB 10.2:

  itemID, COUNT(*) as ordercount,
FROM orders

Syntax of for-loop in SQL Server

How about this:

   Do Something
GO 10

... of course you could put an incremental counter inside it if you need to count.

Git push results in "Authentication Failed"

Make sure you have WRITE permission to push.

read ***write*** admin 

Given final block not properly padded

If you try to decrypt PKCS5-padded data with the wrong key, and then unpad it (which is done by the Cipher class automatically), you most likely will get the BadPaddingException (with probably of slightly less than 255/256, around 99.61%), because the padding has a special structure which is validated during unpad and very few keys would produce a valid padding.

So, if you get this exception, catch it and treat it as "wrong key".

This also can happen when you provide a wrong password, which then is used to get the key from a keystore, or which is converted into a key using a key generation function.

Of course, bad padding can also happen if your data is corrupted in transport.

That said, there are some security remarks about your scheme:

  • For password-based encryption, you should use a SecretKeyFactory and PBEKeySpec instead of using a SecureRandom with KeyGenerator. The reason is that the SecureRandom could be a different algorithm on each Java implementation, giving you a different key. The SecretKeyFactory does the key derivation in a defined manner (and a manner which is deemed secure, if you select the right algorithm).

  • Don't use ECB-mode. It encrypts each block independently, which means that identical plain text blocks also give always identical ciphertext blocks.

    Preferably use a secure mode of operation, like CBC (Cipher block chaining) or CTR (Counter). Alternatively, use a mode which also includes authentication, like GCM (Galois-Counter mode) or CCM (Counter with CBC-MAC), see next point.

  • You normally don't want only confidentiality, but also authentication, which makes sure the message is not tampered with. (This also prevents chosen-ciphertext attacks on your cipher, i.e. helps for confidentiality.) So, add a MAC (message authentication code) to your message, or use a cipher mode which includes authentication (see previous point).

  • DES has an effective key size of only 56 bits. This key space is quite small, it can be brute-forced in some hours by a dedicated attacker. If you generate your key by a password, this will get even faster. Also, DES has a block size of only 64 bits, which adds some more weaknesses in chaining modes. Use a modern algorithm like AES instead, which has a block size of 128 bits, and a key size of 128 bits (for the standard variant).

Error: Cannot invoke an expression whose type lacks a call signature

"Cannot invoke an expression whose type lacks a call signature."

In your code :

class Post extends Component {
  public toggleBody: string;

  constructor() {
    this.toggleBody = this.setProp('showFullBody');

  public showMore(): boolean {
    return this.toggleBody(true);

  public showLess(): boolean {
    return this.toggleBody(false);

You have public toggleBody: string;. You cannot call a string as a function. Hence errors on : this.toggleBody(true); and this.toggleBody(false);

Creating self signed certificate for domain and subdomains - NET::ERR_CERT_COMMON_NAME_INVALID

For everyone who is encountering this and wants to accept the risk to test it, there is a solution: go to Incognito mode in Chrome and you'll be able to open "Advanced" and click "Proceed to some.url".

This can be helpful if you need to check some website which you are maintaining yourself and just testing as a developer (and when you don't yet have proper development certificate configured).

Of course this is NOT FOR PEOPLE using a website in production where this error indicates that there is a problem with website security.