Programs & Examples On #Ora 01036

ORA-01036: illegal variable name/number

ORA-01036: illegal variable name/number when running query through C#

I was having the same problem in an application that I was maintaining, among all the adjustments to prepare the environment, I also spent almost an hour banging my head with this error "ORA-01036: illegal variable name / number" until I found out that the application connection was pointed to an outdated database, so the application passed two more parameters to the outdated database procedure causing the error.

Change Volley timeout duration

I ended up adding a method setCurrentTimeout(int timeout) to the RetryPolicy and it's implementation in DefaultRetryPolicy.

Then I added a setCurrentTimeout(int timeout) in the Request class and called it .

This seems to do the job.

Sorry for my laziness by the way and hooray for open source.

Is calculating an MD5 hash less CPU intensive than SHA family functions?

The real answer is : It depends

There are a couple factors to consider, the most obvious are : the cpu you are running these algorithms on and the implementation of the algorithms.

For instance, me and my friend both run the exact same openssl version and get slightly different results with different Intel Core i7 cpus.

My test at work with an Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz

The 'numbers' are in 1000s of bytes per second processed.
type             16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes
md5              64257.97k   187370.26k   406435.07k   576544.43k   649827.67k
sha1             73225.75k   202701.20k   432679.68k   601140.57k   679900.50k

And his with an Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz

The 'numbers' are in 1000s of bytes per second processed.
type             16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes
md5              51859.12k   156255.78k   350252.00k   513141.73k   590701.52k
sha1             56492.56k   156300.76k   328688.76k   452450.92k   508625.68k

We both are running the exact same binaries of OpenSSL 1.0.1j 15 Oct 2014 from the ArchLinux official package.

My opinion on this is that with the added security of sha1, cpu designers are more likely to improve the speed of sha1 and more programmers will be working on the algorithm's optimization than md5sum.

I guess that md5 will no longer be used some day since it seems that it has no advantage over sha1. I also tested some cases on real files and the results were always the same in both cases (likely limited by disk I/O).

md5sum of a large 4.6GB file took the exact same time than sha1sum of the same file, same goes with many small files (488 in the same directory). I ran the tests a dozen times and they were consitently getting the same results.


It would be very interesting to investigate this further. I guess there are some experts around that could provide a solid answer to why sha1 is getting faster than md5 on newer processors.

How do I move focus to next input with jQuery?

I just wrote a jQuery plugin that does what you are looking for (annoyed that that I couldn't find andy solution myself (tabStop ->

How can I keep a container running on Kubernetes?

Containers are meant to run to completion. You need to provide your container with a task that will never finish. Something like this should work:

apiVersion: v1
kind: Pod
  name: ubuntu
  - name: ubuntu
    image: ubuntu:latest
    # Just spin & wait forever
    command: [ "/bin/bash", "-c", "--" ]
    args: [ "while true; do sleep 30; done;" ]

How can I convert spaces to tabs in Vim or Linux?

Simple Python Script:

import os


for root, dirs, files in os.walk(SOURCE_ROOT):
    for f in files:
        fpath = os.path.join(root,f)
        assert os.path.exists(fpath)
        data = open(fpath, "r").read()
        data = data.replace("    ", "\t")
        outfile = open(fpath, "w")

How to display list items on console window in C#

While the answers with List<T>.ForEach are very good.

I found String.Join<T>(string separator, IEnumerable<T> values) method more useful.

Example :

List<string> numbersStrLst = new List<string>
            { "One", "Two", "Three","Four","Five"};

Console.WriteLine(String.Join(", ", numbersStrLst));//Output:"One, Two, Three, Four, Five"

int[] numbersIntAry = new int[] {1, 2, 3, 4, 5};
Console.WriteLine(String.Join("; ", numbersIntAry));//Output:"1; 2; 3; 4; 5"

Remarks :

If separator is null, an empty string (String.Empty) is used instead. If any member of values is null, an empty string is used instead.

Join(String, IEnumerable<String>) is a convenience method that lets you concatenate each element in an IEnumerable(Of String) collection without first converting the elements to a string array. It is particularly useful with Language-Integrated Query (LINQ) query expressions.

This should work just fine for the problem, whereas for others, having array values. Use other overloads of this same method, String.Join Method (String, Object[])


substring of an entire column in pandas dataframe

case the column isn't string, use astype to convert:

df['col'] = df['col'].astype(str).str[:9]

How to avoid "cannot load such file -- utils/popen" from homebrew on OSX

To me it feels like you have missing header files for popen, which is a C system library.

Check if you have installed xcode successful with the command line tools and have accepted the license.

See this thread for more information: How to install Xcode Command Line Tools

Regex pattern inside SQL Replace function?

I think a simpler and faster approach is iterate by each character of the alphabet:

DECLARE @i int
SET @i = 0

WHILE(@i < 256)

    IF char(@i) NOT IN ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.')      

      UPDATE Table SET Column = replace(Column, char(@i), '')

    SET @i = @i + 1


identifier "string" undefined?

You forgot the namespace you're referring to. Add

using namespace std;

to avoid std::string all the time.

What is the format for the PostgreSQL connection string / URL?

the connection url for postgres syntax:

"Server=host ipaddress;Port=5432;Database=dbname;User Id=userid;Password=password;


"Server=;Port=5432;Database=postgres;User Id=postgres;Password=root;

Git: list only "untracked" files (also, custom commands)

All previous answers which I checked would list the files to be committed, too. Here is a simple and easy solution that only lists files which are not yet in the repo and not subject to .gitignore.

git status --porcelain | awk '/^\?\?/ { print $2; }'


git status --porcelain | grep -v '\?\?'

Function of Project > Clean in Eclipse

It removes whatever already-compiled files are in your project so that you can do a complete fresh rebuild.

JavaScript URL Decode function

Use this


I'm not a great JS programmer, tried all, and this worked awesome!

Regular expression to search multiple strings (Textpad)

To get the lines that contain the texts 8768, 9875 or 2353, use:


What it means:

^                      from the beginning of the line
.*                     get any character except \n (0 or more times)
(8768|9875|2353)       if the line contains the string '8768' OR '9875' OR '2353'
.*                     and get any character except \n (0 or more times)
$                      until the end of the line

If you do want the literal * char, you'd have to escape it:


How to make div background color transparent in CSS


To set background color:

/* Hexadecimal value with color and 100% transparency*/
background-color: #11ffee00;  /* Fully transparent */

/* Special keyword values */
background-color: transparent;

/* HSL value with color and 100% transparency*/
background-color: hsla(50, 33%, 25%, 1.00);  /* 100% transparent */

/* RGB value with color and 100% transparency*/
background-color: rgba(117, 190, 218, 1.0);  /* 100% transparent */

Hadoop "Unable to load native-hadoop library for your platform" warning

I had the same problem with JDK6,I changed the JDK to JDK8,the problem solved. Try to use JDK8!!!

Is Tomcat running?

wget url or curl url where url is a url of the tomcat server that should be available, for example: wget http://localhost:8080. Then check the exit code, if it's 0 - tomcat is up.

Drop multiple columns in pandas

Try this

df.drop(df.iloc[:, 1:69], inplace=True, axis=1)

This works for me

How to add a RequiredFieldValidator to DropDownList control?

If you are using a data source, here's another way to do it without code behind.

Note the following key points:

  • The ListItem of Value="0" is on the source page, not added in code
  • The ListItem in the source will be overwritten if you don't include AppendDataBoundItems="true" in the DropDownList
  • InitialValue="0" tells the validator that this is the value that should fire that validator (as pointed out in other answers)


<asp:DropDownList ID="ddlType" runat="server" DataSourceID="sdsType"
                  DataValueField="ID" DataTextField="Name" AppendDataBoundItems="true">
    <asp:ListItem Value="0" Text="--Please Select--" Selected="True"></asp:ListItem>
<asp:RequiredFieldValidator ID="rfvType" runat="server" ControlToValidate="ddlType" 
                            InitialValue="0" ErrorMessage="Type required"></asp:RequiredFieldValidator>
<asp:SqlDataSource ID="sdsType" runat="server" 
                   ConnectionString='<%$ ConnectionStrings:TESTConnectionString %>'
                   SelectCommand="SELECT ID, Name FROM Type"></asp:SqlDataSource>

Multiple github accounts on the same computer?


change remote url to https:

git remote set-url origin https://[email protected]/USERNAME/PROJECTNAME.git

and you are good to go:

git push

To ensure that the commits appear as performed by USERNAME, one can setup the and for this project, too:

git config USERNAME
git config [email protected]

AngularJs: How to set radio button checked based on model

Use ng-value instead of value.


Version with ng-checked is worse because of the code duplication.

How to extract the nth word and count word occurrences in a MySQL string?

My home-grown regular expression replace function can be used for this.


See this DB-Fiddle demo, which returns the second word ("I") from a famous sonnet and the number of occurrences of it (1).


Assuming MySQL 8 or later is being used (to allow use of a Common Table Expression), the following will return the second word and the number of occurrences of it:

WITH cte AS (
     SELECT digits.idx,
            SUBSTRING_INDEX(SUBSTRING_INDEX(words, '~', digits.idx + 1), '~', -1) word
     (SELECT reg_replace(UPPER(txt),
                         0) AS words
      FROM tbl) delimited
     (SELECT @row := @row + 1 as idx FROM 
      (SELECT @row := -1) t5) digits
     ON LENGTH(REPLACE(words, '~' , '')) <= LENGTH(words) - digits.idx)
SELECT c.word,
FROM cte c
  SELECT word,
         COUNT(*) AS occurrences
  FROM cte
  GROUP BY word
) subq
ON c.word = subq.word
WHERE idx = 1; /* idx is zero-based so 1 here gets the second word */


A few tricks are used in the SQL above and some accreditation is needed. Firstly the regular expression replacer is used to replace all continuous blocks of non-word characters - each being replaced by a single tilda (~) character. Note: A different character could be chosen instead if there is any possibility of a tilda appearing in the text.

The technique from this answer is then used for transforming a string with delimited values into separate row values. It's combined with the clever technique from this answer for generating a table consisting of a sequence of incrementing numbers: 0 - 10,000 in this case.

How can I create a two dimensional array in JavaScript?

Recursive function to create a multi-dimensional array:

var makeArray = function (dims, arr) {          
    if (dims[1] === undefined) {
        return new Array(dims[0]);

    arr = new Array(dims[0]);

    for (var i=0; i<dims[0]; i++) {
        arr[i] = new Array(dims[1]);
        arr[i] = makeArray(dims.slice(1), arr[i]);

    return arr;

Build a 2x3x4x2 4D-Array:

var array = makeArray([2, 3, 4, 2]);    

How to watch for a route change in AngularJS?

This is for the total beginner... like me:


      <a href="#"> Home </a>
      <a href="#Info"> Info </a>

  <div ng-app="myApp" ng-controller="MainCtrl">
    <div ng-view>



//Create App
var app = angular.module("myApp", ["ngRoute"]);

//Configure routes
app.config(function ($routeProvider) {
      .otherwise({ template: "<p>Coming soon</p>" })
      .when("/", {
        template: "<p>Home information</p>"
      .when("/Info", {
        template: "<p>Basic information</p>"
        //templateUrl: "/content/views/Info.html"

app.controller('MainCtrl', function ($scope, $rootScope, $location) {
  $scope.location = $location.path();
  $rootScope.$on('$routeChangeStart', function () {
   //Place code here:....

Hope this helps a total beginner like me. Here is the full working sample:

  <script src=""></script>_x000D_
  <script src=""></script>_x000D_
      <a href="#"> Home </a>_x000D_
      <a href="#Info"> Info </a>_x000D_
  <div ng-app="myApp" ng-controller="MainCtrl">_x000D_
    <div ng-view>_x000D_
//Create App_x000D_
var app = angular.module("myApp", ["ngRoute"]);_x000D_
//Configure routes_x000D_
app.config(function ($routeProvider) {_x000D_
      .otherwise({ template: "<p>Coming soon</p>" })_x000D_
      .when("/", {_x000D_
        template: "<p>Home information</p>"_x000D_
      .when("/Info", {_x000D_
        template: "<p>Basic information</p>"_x000D_
        //templateUrl: "/content/views/Info.html"_x000D_
app.controller('MainCtrl', function ($scope, $rootScope, $location) {_x000D_
  $scope.location = $location.path();_x000D_
  $rootScope.$on('$routeChangeStart', function () {_x000D_
   //Place code here:...._x000D_

lodash: mapping array to object

It can also solve without using any lodash function like this:

let paramsVal = [
    { name: 'foo', input: 'bar' },
    { name: 'baz', input: 'zle' }
let output = {};

paramsVal.forEach(({name, input})=>{
  output[name] = input;


enter image description here

Event when window.location.href changes

Through Jquery, just try

$(window).on('beforeunload', function () {
    //your code goes here on location change 

By using javascript:

window.addEventListener("beforeunload", function (event) {
   //your code goes here on location change 

Refer Document :

How to find the Git commit that introduced a string in any branch?

Not sure why the accepted answer doesn't work in my environment, finally I run below command to get what I need

git log --pretty=format:"%h - %an, %ar : %s"|grep "STRING"

Change EditText hint color when using TextInputLayout

Use TextInputLayout.setDefaultHintTextColor

CodeIgniter Select Query

use Result Rows.
row() method returns a single result row.

$id = $this 
    -> db
    -> select('id')
    -> where('email', $email)
    -> limit(1)
    -> get('users')
    -> row();

then, you can simply use as you want. :)

echo "ID is" . $id;

How to convert answer into two decimal point

Try using the Format function:

Private Sub btncalc_Click(ByVal sender As System.Object,
                          ByVal e As System.EventArgs) Handles btncalc.Click
  txtA.Text = Format(Val(txtD.Text) / Val(txtC.Text) * 
                     Val(txtF.Text) / Val(txtE.Text), "0.00")
  txtB.Text = Format(Val(txtA.Text) * 1000 / Val(txtG.Text), "0.00")
End Sub

Change image source in code behind - Wpf

You just need one line:

ImageViewer1.Source = new BitmapImage(new Uri(@"\myserver\folder1\Customer Data\sample.png"));

Convert seconds to hh:mm:ss in Python

If you use divmod, you are immune to different flavors of integer division:

# show time strings for 3800 seconds

# easy way to get mm:ss
print "%02d:%02d" % divmod(3800, 60)

# easy way to get hh:mm:ss
print "%02d:%02d:%02d" % \
    reduce(lambda ll,b : divmod(ll[0],b) + ll[1:],

# function to convert floating point number of seconds to
# hh:mm:ss.sss
def secondsToStr(t):
    return "%02d:%02d:%02d.%03d" % \
        reduce(lambda ll,b : divmod(ll[0],b) + ll[1:],

print secondsToStr(3800.123)



What is Java String interning?

Since strings are objects and since all objects in Java are always stored only in the heap space, all strings are stored in the heap space. However, Java keeps strings created without using the new keyword in a special area of the heap space, which is called "string pool". Java keeps the strings created using the new keyword in the regular heap space.

The purpose of the string pool is to maintain a set of unique strings. Any time you create a new string without using the new keyword, Java checks whether the same string already exists in the string pool. If it does, Java returns a reference to the same String object and if it does not, Java creates a new String object in the string pool and returns its reference. So, for example, if you use the string "hello" twice in your code as shown below, you will get a reference to the same string. We can actually test this theory out by comparing two different reference variables using the == operator as shown in the following code:

String str1 = "hello";
String str2 = "hello";
System.out.println(str1 == str2); //prints true

String str3 = new String("hello");
String str4 = new String("hello");

System.out.println(str1 == str3); //prints false
System.out.println(str3 == str4); //prints false 

== operator is simply checks whether two references point to the same object or not and returns true if they do. In the above code, str2 gets the reference to the same String object which was created earlier. However, str3 and str4 get references to two entirely different String objects. That is why str1 == str2 returns true but str1 == str3 and str3 == str4 return false . In fact, when you do new String("hello"); two String objects are created instead of just one if this is the first time the string "hello" is used in the anywhere in program - one in the string pool because of the use of a quoted string, and one in the regular heap space because of the use of new keyword.

String pooling is Java's way of saving program memory by avoiding the creation of multiple String objects containing the same value. It is possible to get a string from the string pool for a string created using the new keyword by using String's intern method. It is called "interning" of string objects. For example,

String str1 = "hello";
String str2 = new String("hello");
String str3 = str2.intern(); //get an interned string obj

System.out.println(str1 == str2); //prints false
System.out.println(str1 == str3); //prints true

OCP Java SE 11 Programmer, Deshmukh

How can I read inputs as numbers?

Multiple questions require input for several integers on single line. The best way is to input the whole string of numbers one one line and then split them to integers. Here is a Python 3 version:

a = []
p = input()
p = p.split()      
for i in p:

Also a list comprehension can be used

p = input().split("whatever the seperator is")

And to convert all the inputs from string to int we do the following

x = [int(i) for i in p]
print(x, end=' ')

shall print the list elements in a straight line.

Django download a file

I use this method:

{% if quote.myfile %}
    <div class="">
        <a role="button" 
            href="{{ quote.myfile.url }}"
            download="{{ quote.myfile.url }}"
            class="btn btn-light text-dark ml-0">
            Download attachment
{% endif %}

How to split long commands over multiple lines in PowerShell

Splat Method with Calculations

If you choose splat method, beware calculations that are made using other parameters. In practice, sometimes I have to set variables first then create the hash table. Also, the format doesn't require single quotes around the key value or the semi-colon (as mentioned above).

Example of a call to a function that creates an Excel spreadsheet

$title = "Cut-off File Processing on $start_date_long_str"
$title_row = 1
$header_row = 2
$data_row_start = 3
$data_row_end = $($data_row_start + $($file_info_array.Count) - 1)

# use parameter hash table to make code more readable
$params = @{
    title = $title
    title_row = $title_row
    header_row = $header_row
    data_row_start = $data_row_start
    data_row_end = $data_row_end
$xl_wksht = Create-Excel-Spreadsheet @params

Note: The file array contains information that will affect how the spreadsheet is populated.

how to redirect to external url from c# controller

Use the Controller's Redirect() method.

public ActionResult YourAction()
    // ...
    return Redirect("");


You can't directly perform a server side redirect from an ajax response. You could, however, return a JsonResult with the new url and perform the redirect with javascript.

public ActionResult YourAction()
    // ...
    return Json(new {url = ""});

$.post("@Url.Action("YourAction")", function(data) {
    window.location = data.url;

HTML Text with tags to formatted text in an Excel cell

Nice! Very slick.

I was disappointed that Excel doesn't let us paste to a merged cell and also pastes results containing a break into successive rows below the "target" cell though, as that meant it simply doesn't work for me. I tried a few tweaks (unmerge/remerge, etc.) but then Excel dropped anything below a break, so that was a dead end.

Ultimately, I came up with a routine that'll handle simple tags and not use the "native" Unicode converter that is causing the issue with merged fields. Hope others find this useful:

Public Sub AddHTMLFormattedText(rngA As Range, strHTML As String, Optional blnShowBadHTMLWarning As Boolean = False)
    ' Adds converts text formatted with basic HTML tags to formatted text in an Excel cell
    ' NOTE: Font Sizes not handled perfectly per HTML standard, but I find this method more useful!

    Dim strActualText As String, intSrcPos As Integer, intDestPos As Integer, intDestSrcEquiv() As Integer
    Dim varyTags As Variant, varTag As Variant, varEndTag As Variant, blnTagMatch As Boolean
    Dim intCtr As Integer
    Dim intStartPos As Integer, intEndPos As Integer, intActualStartPos As Integer, intActualEndPos As Integer
    Dim intFontSizeStartPos As Integer, intFontSizeEndPos As Integer, intFontSize As Integer

    varyTags = Array("<b>", "</b>", "<i>", "</i>", "<u>", "</u>", "<sub>", "</sub>", "<sup>", "</sup>")

    ' Remove unhandled/unneeded tags, convert <br> and <p> tags to line feeds
    strHTML = Trim(strHTML)
    strHTML = Replace(strHTML, "<html>", "")
    strHTML = Replace(strHTML, "</html>", "")
    strHTML = Replace(strHTML, "<p>", "")
    While LCase(Right$(strHTML, 4)) = "</p>" Or LCase(Right$(strHTML, 4)) = "<br>"
        strHTML = Left$(strHTML, Len(strHTML) - 4)
        strHTML = Trim(strHTML)
    strHTML = Replace(strHTML, "<br>", vbLf)
    strHTML = Replace(strHTML, "</p>", vbLf)

    strHTML = Trim(strHTML)

    ReDim intDestSrcEquiv(1 To Len(strHTML))
    strActualText = ""
    intSrcPos = 1
    intDestPos = 1
    Do While intSrcPos <= Len(strHTML)
        blnTagMatch = False
        For Each varTag In varyTags
            If LCase(Mid$(strHTML, intSrcPos, Len(varTag))) = varTag Then
                blnTagMatch = True
                intSrcPos = intSrcPos + Len(varTag)
                If intSrcPos > Len(strHTML) Then Exit Do
                Exit For
            End If
        If blnTagMatch = False Then
            varTag = "<font size"
            If LCase(Mid$(strHTML, intSrcPos, Len(varTag))) = varTag Then
                blnTagMatch = True
                intEndPos = InStr(intSrcPos, strHTML, ">")
                intSrcPos = intEndPos + 1
                If intSrcPos > Len(strHTML) Then Exit Do
                varTag = "</font>"
                If LCase(Mid$(strHTML, intSrcPos, Len(varTag))) = varTag Then
                    blnTagMatch = True
                    intSrcPos = intSrcPos + Len(varTag)
                    If intSrcPos > Len(strHTML) Then Exit Do
                End If
            End If
        End If
        If blnTagMatch = False Then
            strActualText = strActualText & Mid$(strHTML, intSrcPos, 1)
            intDestSrcEquiv(intSrcPos) = intDestPos
            intDestPos = intDestPos + 1
            intSrcPos = intSrcPos + 1
        End If

    ' Clear any bold/underline/italic/superscript/subscript formatting from cell
    rngA.Font.Bold = False
    rngA.Font.Underline = False
    rngA.Font.Italic = False
    rngA.Font.Subscript = False
    rngA.Font.Superscript = False

    rngA.Value = strActualText

    ' Now start applying Formats!"
    ' Start with Font Size first
    intSrcPos = 1
    intDestPos = 1
    Do While intSrcPos <= Len(strHTML)
        varTag = "<font size"
        If LCase(Mid$(strHTML, intSrcPos, Len(varTag))) = varTag Then
            intFontSizeStartPos = InStr(intSrcPos, strHTML, """") + 1
            intFontSizeEndPos = InStr(intFontSizeStartPos, strHTML, """") - 1
            If intFontSizeEndPos - intFontSizeStartPos <= 3 And intFontSizeEndPos - intFontSizeStartPos > 0 Then
                Debug.Print Mid$(strHTML, intFontSizeStartPos, intFontSizeEndPos - intFontSizeStartPos + 1)
                If Mid$(strHTML, intFontSizeStartPos, 1) = "+" Then
                    intFontSizeStartPos = intFontSizeStartPos + 1
                    intFontSize = 11 + 2 * Mid$(strHTML, intFontSizeStartPos, intFontSizeEndPos - intFontSizeStartPos + 1)
                ElseIf Mid$(strHTML, intFontSizeStartPos, 1) = "-" Then
                    intFontSizeStartPos = intFontSizeStartPos + 1
                    intFontSize = 11 - 2 * Mid$(strHTML, intFontSizeStartPos, intFontSizeEndPos - intFontSizeStartPos + 1)
                    intFontSize = Mid$(strHTML, intFontSizeStartPos, intFontSizeEndPos - intFontSizeStartPos + 1)
                End If
                ' Error!
                GoTo HTML_Err
            End If
            intEndPos = InStr(intSrcPos, strHTML, ">")
            intSrcPos = intEndPos + 1
            intStartPos = intSrcPos
            If intSrcPos > Len(strHTML) Then Exit Do
            While intDestSrcEquiv(intStartPos) = 0 And intStartPos < Len(strHTML)
                intStartPos = intStartPos + 1
            If intStartPos >= Len(strHTML) Then GoTo HTML_Err ' HTML is bad!
            varEndTag = "</font>"
            intEndPos = InStr(intSrcPos, LCase(strHTML), varEndTag)
            If intEndPos = 0 Then GoTo HTML_Err ' HTML is bad!
            While intDestSrcEquiv(intEndPos) = 0 And intEndPos > intSrcPos
                intEndPos = intEndPos - 1
            If intEndPos > intSrcPos Then
                intActualStartPos = intDestSrcEquiv(intStartPos)
                intActualEndPos = intDestSrcEquiv(intEndPos)
                rngA.Characters(intActualStartPos, intActualEndPos - intActualStartPos + 1) _
                    .Font.Size = intFontSize
            End If
        End If
        intSrcPos = intSrcPos + 1

    'Now do remaining tags
    intSrcPos = 1
    intDestPos = 1
    Do While intSrcPos <= Len(strHTML)
        If intDestSrcEquiv(intSrcPos) = 0 Then
            ' This must be a Tag!
            For intCtr = 0 To UBound(varyTags) Step 2
                varTag = varyTags(intCtr)
                intStartPos = intSrcPos + Len(varTag)
                While intDestSrcEquiv(intStartPos) = 0 And intStartPos < Len(strHTML)
                    intStartPos = intStartPos + 1
                If intStartPos >= Len(strHTML) Then GoTo HTML_Err ' HTML is bad!
                If LCase(Mid$(strHTML, intSrcPos, Len(varTag))) = varTag Then
                    varEndTag = varyTags(intCtr + 1)
                    intEndPos = InStr(intSrcPos, LCase(strHTML), varEndTag)
                    If intEndPos = 0 Then GoTo HTML_Err ' HTML is bad!
                    While intDestSrcEquiv(intEndPos) = 0 And intEndPos > intSrcPos
                        intEndPos = intEndPos - 1
                    If intEndPos > intSrcPos Then
                        intActualStartPos = intDestSrcEquiv(intStartPos)
                        intActualEndPos = intDestSrcEquiv(intEndPos)
                        With rngA.Characters(intActualStartPos, intActualEndPos - intActualStartPos + 1).Font
                            If varTag = "<b>" Then
                                .Bold = True
                            ElseIf varTag = "<i>" Then
                                .Italic = True
                            ElseIf varTag = "<u>" Then
                                .Underline = True
                            ElseIf varTag = "<sup>" Then
                                .Superscript = True
                            ElseIf varTag = "<sub>" Then
                                .Subscript = True
                            End If
                        End With
                    End If
                    intSrcPos = intSrcPos + Len(varTag) - 1
                    Exit For
                End If
        End If
        intSrcPos = intSrcPos + 1
        intDestPos = intDestPos + 1
    Exit Sub
    ' There was an error with the Tags. Show warning if requested.
    If blnShowBadHTMLWarning Then
        MsgBox "There was an error with the Tags in the HTML file. Could not apply formatting."
    End If
End Sub

Note this doesn't care about tag nesting, instead only requiring a close tag for every open tag, and assuming the close tag nearest the opening tag applies to the opening tag. Properly nested tags will work fine, while improperly nested tags will not be rejected and may or may not work.

Calculating moving average

vector_avg <- function(x){
  sum_x = 0
  for(i in 1:length(x)){
      sum_x = sum_x + x[i]

JSON Parse File Path

Loading local JSON file

Use something like this

$.getJSON("../../data/file.json", function(json) {
    console.log(json); // this will show the info in firebug console 

Regular expression to match non-ASCII characters?

I had a problem with \p working as expected, so I just used a different strategy like:


Find anything that is not a tab character until the next tab character... obviously this depends on your search source, but you get the idea. Now I don't have to figure out what unicode characters work and don't work etc.

Getting Access Denied when calling the PutObject operation with bucket-level permission

I was having a similar problem. I was not using the ACL stuff, so I didn't need s3:PutObjectAcl.

In my case, I was doing (in Serverless Framework YML):

- Effect: Allow
    - s3:PutObject
  Resource: "arn:aws:s3:::MyBucketName"

Instead of:

- Effect: Allow
    - s3:PutObject
  Resource: "arn:aws:s3:::MyBucketName/*"

Which adds a /* to the end of the bucket ARN.

Hope this helps.

How can I check if some text exist or not in the page using Selenium?

You can check for text in your page source as follow:

Assert.IsTrue(driver.PageSource.Contains("Your Text Here"))

Stretch image to fit full container width bootstrap

First of all if the size of the image is smaller than the container, then only "img-fluid" class will not solve your problem. you have to set the width of image to 100%, for that you can use Bootstrap class "w-100". keep in mind that "container-fluid" and "col-12" class sets left and right padding to 15px and "row" class sets left and right margin to "-15px" by default. make sure to set them to 0.

Note: "px-0" is a bootstrap class which sets left and right padding to 0 and
"mx-0" is a bootstrap class which sets left and right margin to 0

P.S. i am using Bootstrap 4.0 version.

 <div class="container-fluid px-0">
        <div class="row mx-0">
            <div class="col-12 px-0">
            <img src="images/top.jpg" class="img-fluid w-100">

How can I remove all files in my git repo and update/push from my local git repo?

I have tried like this

git rm --cached -r * -f

And it is working for me.

Pass a string parameter in an onclick function

Try this...


<button id="a1" type="button" onclick="return a1_onclick('a1')">a1</button>


<script language="javascript" type="text/javascript">
    function a1_onclick(id) {
        document.getElementById(id).style.backgroundColor = "#F00";

Note: be sure of sending arguments between ' ' signs like ('a1') in HTML code

Can you get the number of lines of code from a GitHub repository?

Not currently possible on or their API-s

I have talked to customer support and confirmed that this can not be done on They have passed the suggestion along to the Github team though, so hopefully it will be possible in the future. If so, I'll be sure to edit this answer.

Meanwhile, Rory O'Kane's answer is a brilliant alternative based on cloc and a shallow repo clone.

No 'Access-Control-Allow-Origin' - Node / Apache Port Issue

Apart from all listed answers, I had the same error

I have both access to frontend and backend, I already added cors module app.use(cors()); Still, I was struggling with this error.

After some debugging, I found the issue. When I upload a media which size was more than 1 MB then the error was thrown by Nginx server


    <title>413 Request Entity Too Large</title>

        <h1>413 Request Entity Too Large</h1>


But in the console of frontend, I found the error

Access to XMLHttpRequest at '' from origin '' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

So It makes confusion here. But the route cause of this error was from nginx configuration. It's just because the directive client_max_body_size value has been set to 0 by default. It determines what the allowable HTTP request size can be is client_max_body_size. This directive may already be defined in your nginx.conf file located at /etc/nginx/nginx.conf Now you need to add/edit the value of the directive client_max_body_size either at http or server.

server {
    client_max_body_size 100M;

Once you have set your desired value, save your changes and reload Nginx: service nginx reload

After these changes, It's working well


How can I do an UPDATE statement with JOIN in SQL Server?

Another example why SQL isn't really portable.

For MySQL it would be:

update ud, sale
set ud.assid = sale.assid
where sale.udid =;

For more info read multiple table update:

UPDATE [LOW_PRIORITY] [IGNORE] table_references
    SET col_name1={expr1|DEFAULT} [, col_name2={expr2|DEFAULT}] ...
    [WHERE where_condition]

how to pass value from one php page to another using session

Use something like this:


$_SESSION['myValue']=3; // You can set the value however you like.

Any other PHP page:

echo $_SESSION['myValue'];

A few notes to keep in mind though: You need to call session_start() BEFORE any output, HTML, echos - even whitespace.

You can keep changing the value in the session - but it will only be able to be used after the first page - meaning if you set it in page 1, you will not be able to use it until you get to another page or refresh the page.

The setting of the variable itself can be done in one of a number of ways:


And if you want to check if the variable is set before getting a potential error, use something like this:

    echo $_SESSION['myValue'];
    echo "Session not set yet.";

CSS background-image not working

The easy way is that, copy and past this background-image: url(../slide_button.png); instead of background-image: url(slide_button.png); In such case we need to use ../ before path. Either you need to give full path. One other thing is that, in case before doing any change just clear the browser history and then refresh the page.

Send a file via HTTP POST with C#

I had got the same problem and this following code answered perfectly at this problem :

//Identificate separator
string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

//Creation and specification of the request
HttpWebRequest wr = (HttpWebRequest)WebRequest.Create(url); //sVal is id for the webService
wr.ContentType = "multipart/form-data; boundary=" + boundary;
wr.Method = "POST";
wr.KeepAlive = true;
wr.Credentials = System.Net.CredentialCache.DefaultCredentials;

string sAuthorization = "login:password";//AUTHENTIFICATION BEGIN
byte[] toEncodeAsBytes = System.Text.ASCIIEncoding.ASCII.GetBytes(sAuthorization);
string returnValue = System.Convert.ToBase64String(toEncodeAsBytes);
wr.Headers.Add("Authorization: Basic " + returnValue); //AUTHENTIFICATION END
Stream rs = wr.GetRequestStream();

string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}"; //For the POST's format

//Writting of the file
rs.Write(boundarybytes, 0, boundarybytes.Length);
byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(Server.MapPath("questions.pdf"));
rs.Write(formitembytes, 0, formitembytes.Length);

rs.Write(boundarybytes, 0, boundarybytes.Length);

string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
string header = string.Format(headerTemplate, "file", "questions.pdf", contentType);
byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
rs.Write(headerbytes, 0, headerbytes.Length);

FileStream fileStream = new FileStream(Server.MapPath("questions.pdf"), FileMode.Open, FileAccess.Read);
byte[] buffer = new byte[4096];
int bytesRead = 0;
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
    rs.Write(buffer, 0, bytesRead);

byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
rs.Write(trailer, 0, trailer.Length);
rs = null;

WebResponse wresp = null;
    //Get the response
    wresp = wr.GetResponse();
    Stream stream2 = wresp.GetResponseStream();
    StreamReader reader2 = new StreamReader(stream2);
    string responseData = reader2.ReadToEnd();
catch (Exception ex)
    string s = ex.Message;
    if (wresp != null)
        wresp = null;
    wr = null;

Proper way to use **kwargs in Python

I think the proper way to use **kwargs in Python when it comes to default values is to use the dictionary method setdefault, as given below:

class ExampleClass:
    def __init__(self, **kwargs):
        kwargs.setdefault('val', value1)
        kwargs.setdefault('val2', value2)

In this way, if a user passes 'val' or 'val2' in the keyword args, they will be used; otherwise, the default values that have been set will be used.

How to hide element label by element id in CSS?

You probably have to add a class/id to and then make another CSS declaration that hides it as well.

Visual Studio: Relative Assembly References Paths

Yes, just create a directory in your solution like lib/, and then add your dll to that directory in the filesystem and add it in the project (Add->Existing Item->etc). Then add the reference based on your project.

I have done this several times under svn and under cvs.

Tomcat: How to find out running tomcat version

if you can upload a JSP file you may print out some info like in this example:

Save this code into a file called tomcat_version.jsp:

    Tomcat Version : <%= application.getServerInfo() %><br>    
    Servlet Specification Version : 
<%= application.getMajorVersion() %>.<%= application.getMinorVersion() %> <br>    
    JSP version :
<%=JspFactory.getDefaultFactory().getEngineInfo().getSpecificationVersion() %><br>

When you access,, the output should look similar to:

Tomcat Version : Apache Tomcat/5.5.25
Servlet Specification Version : 2.4
JSP version: 2.0

Please explain the exec() function and its family

Functions in the exec() family have different behaviours:

  • l : arguments are passed as a list of strings to the main()
  • v : arguments are passed as an array of strings to the main()
  • p : path/s to search for the new running program
  • e : the environment can be specified by the caller

You can mix them, therefore you have:

  • int execl(const char *path, const char *arg, ...);
  • int execlp(const char *file, const char *arg, ...);
  • int execle(const char *path, const char *arg, ..., char * const envp[]);
  • int execv(const char *path, char *const argv[]);
  • int execvp(const char *file, char *const argv[]);
  • int execvpe(const char *file, char *const argv[], char *const envp[]);

For all of them the initial argument is the name of a file that is to be executed.

For more information read exec(3) man page:

man 3 exec  # if you are running a UNIX system

support FragmentPagerAdapter holds reference to old fragments

I faced the same issue but my ViewPager was inside a TopFragment which created and set an adapter using setAdapter(new FragmentPagerAdapter(getChildFragmentManager())).

I fixed this issue by overriding onAttachFragment(Fragment childFragment) in the TopFragment like this:

public void onAttachFragment(Fragment childFragment) {
    if (childFragment instanceof OnboardingDiamondsFragment) {
        mChildFragment = (ChildFragment) childFragment;


As known already (see answers above), when the childFragmentManager recreate itself, it also create the fragments which were inside the viewPager.
The important part is that after that, he calls onAttachFragment and now we have a reference to the new recreated fragment!

Hope this will help anyone getting this old Q like me :)

How can I remove a trailing newline?

This would replicate exactly perl's chomp (minus behavior on arrays) for "\n" line terminator:

def chomp(x):
    if x.endswith("\r\n"): return x[:-2]
    if x.endswith("\n") or x.endswith("\r"): return x[:-1]
    return x

(Note: it does not modify string 'in place'; it does not strip extra trailing whitespace; takes \r\n in account)

require_once :failed to open stream: no such file or directory

this will work as well

 require_once(realpath($_SERVER["DOCUMENT_ROOT"]) .'/mysite/php/includes/');

Convert time.Time to string

package main                                                                                                                                                           

import (

// @link

func main() {

    //caution : format string is `2006-01-02 15:04:05.000000000`
    current := time.Now()

    fmt.Println("origin : ", current.String())
    // origin :  2016-09-02 15:53:07.159994437 +0800 CST

    fmt.Println("mm-dd-yyyy : ", current.Format("01-02-2006"))
    // mm-dd-yyyy :  09-02-2016

    fmt.Println("yyyy-mm-dd : ", current.Format("2006-01-02"))
    // yyyy-mm-dd :  2016-09-02

    // separated by .
    fmt.Println(" : ", current.Format("2006.01.02"))
    // :  2016.09.02

    fmt.Println("yyyy-mm-dd HH:mm:ss : ", current.Format("2006-01-02 15:04:05"))
    // yyyy-mm-dd HH:mm:ss :  2016-09-02 15:53:07

    // StampMicro
    fmt.Println("yyyy-mm-dd HH:mm:ss: ", current.Format("2006-01-02 15:04:05.000000"))
    // yyyy-mm-dd HH:mm:ss:  2016-09-02 15:53:07.159994

    fmt.Println("yyyy-mm-dd HH:mm:ss: ", current.Format("2006-01-02 15:04:05.000000000"))
    // yyyy-mm-dd HH:mm:ss:  2016-09-02 15:53:07.159994437

Get the length of a String

Best way to count String in Swift is this:

var str = "Hello World"
var length = count(str.utf16)

findAll() in yii

Another simple way get by using findall in yii

$id =101; 
$comments = EmailArchive::model()->findAll(array("condition"=>"':email_id'=$id"));
foreach($comments as $comments_1) 
echo  "email:".$comments_1['email_id'];

how do I get the bullet points of a <ul> to center with the text?

Here's how you do it.

First, decorate your list this way:

<div class="p">
<div class="text-bullet-centered">&#8277;</div>
text text text text text text text text text text text text text text text text 
text text text text text text text text text text text text text text text text 
text text text text text text text text text text text text text text text text 
text text text text text text text text text text text text text text text text 
<div class="p">
<div class="text-bullet-centered">&#8277;</div>
text text text text text text text text text text text text text text text text 
text text text text text text text text text text text text text text text text 
text text text text text text text text text text text text text text text text 
text text text text text text text text text text text text text text text text 

Add this CSS:

.p {
    position: relative;
    margin: 20px;
    margin-left: 50px;
.text-bullet-centered {
    position: absolute;
    left: -40px;
    top: 50%;
    transform: translate(0%,-50%);
    font-weight: bold;

And voila, it works. Resize a window, to see that it indeed works.

As a bonus, you can easily change font and color of bullets, which is very hard to do with normal lists.

.p {_x000D_
  position: relative;_x000D_
  margin: 20px;_x000D_
  margin-left: 50px;_x000D_
.text-bullet-centered {_x000D_
  position: absolute;_x000D_
  left: -40px;_x000D_
  top: 50%;_x000D_
  transform: translate(0%, -50%);_x000D_
  font-weight: bold;_x000D_
<div class="p">_x000D_
  <div class="text-bullet-centered">&#8277;</div>_x000D_
  text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text_x000D_
  text text text text text text text text text text text text text_x000D_
<div class="p">_x000D_
  <div class="text-bullet-centered">&#8277;</div>_x000D_
  text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text text_x000D_
  text text text text text text text text text text text text text_x000D_

How do I use dataReceived event of the SerialPort Port Object in C#?

I believe this won't work because you are using a console application and there is no Event Loop running. An Event Loop / Message Pump used for event handling is setup automatically when a Winforms application is created, but not for a console app.

How to format DateTime to 24 hours time?

Use upper-case HH for 24h format:

String s = curr.ToString("HH:mm");

See DateTime.ToString Method.

Change directory command in Docker?

I was wondering if two times WORKDIR will work or not, but it worked :)

FROM ubuntu:18.04

RUN apt-get update && \
    apt-get install -y python3.6

WORKDIR /usr/src

COPY ./ ./

WORKDIR /usr/src/src

CMD ["python3", ""]

Use CSS3 transitions with gradient backgrounds

One work-around is to transition the background position to give the effect that the gradient is changing:

CSS3 gradient transition with background-position

Although you can’t directly animate gradients using the CSS transition property, it is possible to animate the background-position property to achieve a simple gradient animation:

The code for this is dead simple:

#DemoGradient{  _x000D_
    background: -webkit-linear-gradient(#C7D3DC,#5B798E);  _x000D_
    background: -moz-linear-gradient(#C7D3DC,#5B798E);  _x000D_
    background: -o-linear-gradient(#C7D3DC,#5B798E);  _x000D_
    background: linear-gradient(#C7D3DC,#5B798E);  _x000D_
    -webkit-transition: background 1s ease-out;  _x000D_
    -moz-transition: background 1s ease-out;  _x000D_
    -o-transition: background 1s ease-out;  _x000D_
    transition: background 1s ease-out;  _x000D_
    background-size:1px 200px;  _x000D_
    border-radius: 10px;  _x000D_
    border: 1px solid #839DB0;  _x000D_
    cursor:pointer;  _x000D_
    width: 150px;  _x000D_
    height: 100px;  _x000D_
}  _x000D_
#DemoGradient:Hover{  _x000D_
    background-position:100px;  _x000D_
<div id="DemoGradient"></div>  

How to scroll to bottom in a ScrollView on activity startup

 scrollView.postDelayed(new Runnable() {
        public void run() {

Twitter Bootstrap tabs not working: when I click on them nothing happens

This solved it when none of the other examples did:

$('#myTab a').click(function (e) {

What is Android's file system?

Similar to Linux:

  • /boot

  • /system

  • /recovery

  • /data

  • /cache

  • /misc

How to load npm modules in AWS Lambda?

Hope this helps, with Serverless framework you can do something like this:

  1. Add these things in your serverless.yml file:

plugins: - serverless-webpack custom: webpackIncludeModules: forceInclude: - <your package name> (for example: node-fetch) 2. Then create your Lambda function, deploy it by serverless deploy, the package that included in serverless.yml will be there for you.

For more information about serverless:

How do I compare a value to a backslash?

If message.value[] is string:

if message.value[0] in ('/', '\'):

If it not str

Why do I have to define LD_LIBRARY_PATH with an export every time I run my application?

Did you 'export' in your .bashrc?

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:"/path/to/library"

C-like structures in Python

Use a named tuple, which was added to the collections module in the standard library in Python 2.6. It's also possible to use Raymond Hettinger's named tuple recipe if you need to support Python 2.4.

It's nice for your basic example, but also covers a bunch of edge cases you might run into later as well. Your fragment above would be written as:

from collections import namedtuple
MyStruct = namedtuple("MyStruct", "field1 field2 field3")

The newly created type can be used like this:

m = MyStruct("foo", "bar", "baz")

You can also use named arguments:

m = MyStruct(field1="foo", field2="bar", field3="baz")

SSRS Query execution failed for dataset

I encountered a similar error message. I was able to fix it without enabling remote errors.

In Report Builder 3.0, when I used the Run button to run the report, an error alert appeared, saying

An error has occurred during report processing. (rsProcessingAborted)
[OK] [Details...]

Pressing the details button gave me a text box where I saw this text:

For more information about this error navigate to the report server
on the local server machine, or enable remote errors
Query execution failed for dataset 'DataSet1'. (rsErrorExecutingCommand)

I was confused and frustrated, because my report did not have a dataset named 'DataSet1'. I even opened the .rdl file in a text editor to be sure. After a while, I noticed that there was more text in the text box below what I could read. The full error message was:

For more information about this error navigate to the report server
on the local server machine, or enable remote errors
Query execution failed for dataset 'DataSet1'. (rsErrorExecutingCommand)

The execution failed for the shared data set 'CustomerDetailsDataSet'.  
An error has occurred during report processing. (rsProcessingAborted)

I did have a shared dataset named 'CustomerDetailsDataSet'. I opened the query (which was a full SQL query entered in text mode) in SQL Server Management Studio, and ran it there. I got error messages which clearly pointed to a certain table, where a column I had been using had been renamed and changed.

From that point, it was straightforward to modify my query so that it worked with the new column, then paste that modification into the shared dataset 'CustomerDetailsDataSet', and then nudge the report in Report Builder to recognise the change to the shared dataset.

After this fix, my reports no longer triggered this error.

How to find Max Date in List<Object>?

Just use Kotlin!

val list = listOf(user1, user2, user3)
val maxDate = list.maxBy { }?.date

Insert data into table with result from another select query

If table_2 is empty, then try the following insert statement:

insert into table_2 (itemid,location1) 
select itemid,quantity from table_1 where locationid=1

If table_2 already contains the itemid values, then try this update statement:

update table_2 set location1=
(select quantity from table_1 where locationid=1 and table_1.itemid = table_2.itemid)

How to check if a value exists in an object using JavaScript

You can try this:

function checkIfExistingValue(obj, key, value) {
    return obj.hasOwnProperty(key) && obj[key] === value;
var test = [{name : "jack", sex: F}, {name: "joe", sex: M}]
console.log(test.some(function(person) { return checkIfExistingValue(person, "name", "jack"); }));

How to plot data from multiple two column text files with legends in Matplotlib?

Assume your file looks like this and is named test.txt (space delimited):

1 2
3 4
5 6
7 8



import numpy as np
import matplotlib.pyplot as plt

with open("test.txt") as f:
    data =

data = data.split('\n')

x = [row.split(' ')[0] for row in data]
y = [row.split(' ')[1] for row in data]

fig = plt.figure()

ax1 = fig.add_subplot(111)

ax1.set_title("Plot title...")    
ax1.set_xlabel('your x label..')
ax1.set_ylabel('your y label...')

ax1.plot(x,y, c='r', label='the data')

leg = ax1.legend()

Example plot:

I find that browsing the gallery of plots on the matplotlib site helpful for figuring out legends and axes labels.

How to write oracle insert script with one field as CLOB?

Keep in mind that SQL strings can not be larger than 4000 bytes, while Pl/SQL can have strings as large as 32767 bytes. see below for an example of inserting a large string via an anonymous block which I believe will do everything you need it to do.

note I changed the varchar2(32000) to CLOB

set serveroutput ON 
CREATE TABLE testclob 
     id NUMBER, 
     c  CLOB, 
     d  VARCHAR2(4000) 

    reallybigtextstring CLOB := '123'; 
    i                   INT; 
    WHILE Length(reallybigtextstring) <= 60000 LOOP 
        reallybigtextstring := reallybigtextstring 
                               || '000000000000000000000000000000000'; 
    END LOOP; 

    INSERT INTO testclob 
    VALUES     (0, 

    dbms_output.Put_line('I have finished inputting your clob: ' 
                         || Length(reallybigtextstring)); 

FROM   testclob; 

 "I have finished inputting your clob: 60030"

Google Maps API 3 - Custom marker color for default (dot) marker

Combine a symbol-based marker whose path draws the outline, with a '?' character for the center. You can substitute the dot with other text ('A', 'B', etc.) as desired.

This function returns options for a marker with the a given text (if any), text color, and fill color. It uses the text color for the outline.

function createSymbolMarkerOptions(text, textColor, fillColor) {
    return {
        icon: {
            path: 'M 0,0 C -2,-20 -10,-22 -10,-30 A 10,10 0 1,1 10,-30 C 10,-22 2,-20 0,0 z',
            fillColor: fillColor,
            fillOpacity: 1,
            strokeColor: textColor,
            strokeWeight: 1.8,
            labelOrigin: { x: 0, y: -30 }
        label: {
            text: text || '?',
            color: textColor

Java Class.cast() vs. cast operator

Generally the cast operator is preferred to the Class#cast method as it's more concise and can be analyzed by the compiler to spit out blatant issues with the code.

Class#cast takes responsibility for type checking at run-time rather than during compilation.

There are certainly use-cases for Class#cast, particularly when it comes to reflective operations.

Since lambda's came to java I personally like using Class#cast with the collections/stream API if I'm working with abstract types, for example.

Dog findMyDog(String name, Breed breed) {
                      .filter(dog -> dog.getName().equalsIgnoreCase(name))
                      .filter(dog -> dog.getBreed() == breed)

How do AX, AH, AL map onto EAX?

No -- AL is the 8 least significant bits of AX. AX is the 16 least significant bits of EAX.

Perhaps it's easiest to deal with if we start with 04030201h in eax. In this case, AX will contain 0201h, AH wil contain 02h and AL will contain 01h.

Session state can only be used when enableSessionState is set to true either in a configuration

I realise there is an accepted answer, but this may help people. I found I had a similar problem with a ASP.NET site using NET 3.5 framework when running it in Visual Studio 2012 using IIS Express 8. I'd tried all of the above solutions and none worked - in the end running the solution in the in-built VS 2012 webserver worked. Not sure why, but I suspect it was a link between 3.5 framework and IIS 8.

Open a selected file (image, pdf, ...) programmatically from my Android Application?

To Open a File in Android Programatically,you can use this code :- We use File Provider for internal file access .You can also see details about File Provider here in this linkfileprovidr1,file provider2,file provider3. Create a File Provider and defined in Manifest File .




Define file_path in resources file.

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="">
        path="Android/data/" />

    <external-files-path name="vivalinkComProp" path="Android/data/"/>
        path="." />
        path="." />
        path="." />
        path="." />
        path="." />


Define Intent For View

String directory_path = Environment.getExternalStorageDirectory().getPath() + "/MyFile/";
String targetPdf = directory_path + fileName + ".pdf";
File filePath = new File(targetPdf);

Intent intentShareFile = new Intent(Intent.ACTION_VIEW);
File fileWithinMyDir = new File(targetPdf);
Uri bmpUri = FileProvider.getUriForFile(activity, "", filePath);
if (fileWithinMyDir.exists()) {
    startActivity(Intent.createChooser(intentShareFile, "Open File Using..."));


You can use different way to create a file provider in android . Hope this will help you.

Save and load MemoryStream to/from a file

The stream should really by disposed of even if there's an exception (quite likely on file I/O) - using clauses are my favourite approach for this, so for writing your MemoryStream, you can use:

using (FileStream file = new FileStream("file.bin", FileMode.Create, FileAccess.Write)) {

And for reading it back:

using (FileStream file = new FileStream("file.bin", FileMode.Open, FileAccess.Read)) {
    byte[] bytes = new byte[file.Length];
    file.Read(bytes, 0, (int)file.Length);
    ms.Write(bytes, 0, (int)file.Length);

If the files are large, then it's worth noting that the reading operation will use twice as much memory as the total file size. One solution to that is to create the MemoryStream from the byte array - the following code assumes you won't then write to that stream.

MemoryStream ms = new MemoryStream(bytes, writable: false);

My research (below) shows that the internal buffer is the same byte array as you pass it, so it should save memory.

byte[] testData = new byte[] { 104, 105, 121, 97 };
var ms = new MemoryStream(testData, 0, 4, false, true);
Assert.AreSame(testData, ms.GetBuffer());

rbind error: "names do not match previous names"

easy enough to use the unname() function:

data.frame <- unname(data.frame)

How to add a new line in textarea element?

just use <br>

blablablabla <br> kakakakakak <br> fafafafafaf 


Setting a max height on a table

Use divs with max height and min height around the content that needs to scroll.


td div{

Getting the source of a specific image element with jQuery

If you do not specifically need the alt text of an image, then you can just target the class/id of the image.

     enter code here

I know it’s not quite answering the question, though I’d spent ages trying to figure this out and this question gave me the solution :). In my case I needed to hide any image tags with a specific src.

$('img.propImg').each(function(){ //for each loop that gets all the images. 
        if($(this).attr('src') == "img/{{images}}") { // if the src matches this
        $(this).css("display", "none") // hide the image.

How to enable named/bind/DNS full logging?

Run command rndc querylog on or add querylog yes; to options{}; section in named.conf to activate that channel.

Also make sure you’re checking correct directory if your bind is chrooted.

How to make Git "forget" about a file that was tracked but is now in .gitignore?

Do the following steps serially,you will be fine.

1.remove the mistakenly added files from the directory/storage. You can use "rm -r"(for linux) command or delete them by browsing the directories. Or move them to another location on your PC.[You maybe need to close the IDE if running for moving/removing]

2.add the files / directories to gitignore file now and save it. remove them from git cache by using these commands (if there are more than one directory, remove them one by one by repeatedly issuing this command)

git rm -r --cached path-to-those-files do a commit and push, use these commands. This will remove those files from git remote and make git stop tracking those files.

git add .
git commit -m "removed unnecessary files from git"
git push origin

What does "collect2: error: ld returned 1 exit status" mean?

Try running task manager to determine if your program is still running.

If it is running then stop it and run it again. the [Error] ld returned 1 exit status will not come back

Best ways to teach a beginner to program?

I've had to work with several beginner (never wrote a line of code) programmers, and I'll be doing an after school workshop with high school students this fall. This is the closest thing I've got to documentation. It's still a work in progress, but I hope it helps.

1) FizzBuzz. Start with command line programs. You can write some fun games, or tools, very quickly, and you learn all of the language features very quickly without having to learn the GUI tools first. These early apps should be simple enough that you won't need to use any real debugging tools to make them work.

If nothing else things like FizzBuzz are good projects. Your first few apps should not have to deal with DBs, file system, configuration, ect. These are concepts which just confuse most people, and when you're just learning the syntax and basic framework features you really don't need more complexity.

Some projects:

  • Hello World!
  • Take the year of my birth, and calculate my age (just (now - then) no month corrections). (simple math, input, output)
  • Ask for a direction(Up, down, left, right), then tell the user their fate (fall in a hole, find a cake, ect). (Boolean logic)
  • FizzBuzz, but count once every second. (Loops, timers, and more logic)
  • Depending on their age some really like an app which calls the users a random insult at some interval. (Loops, arrays, timers, and random if you make the interval random)

2) Simple Project Once they have a good grasp of language features, you can start a project(simple, fun games work good.). You should try to have the first project be able to be completed within 6-12 hours. Don't spend time to architect it early. Let them design it even if it sucks. If it falls apart, talk about what happened and why it failed, then pick another topic and start again.

This is where you start introducing the debugging capabilities of your tools. Even if you can see the problem by reading the code you should teach them how to use the tools, and then show them how you could see it. That serves the dual purpose of teaching the debugging tools and teaching how to ID errors without tools.

Once, or if, the project gets functional you can use it to introduce refactoring tools. Its good if you can then expand the project with some simple features which you never planned for. This usually means refactoring and significant debugging, since very few people write even half decent code their first time.

Some projects:

  • Hangman game
  • Experimenting with robotics(Vex and Mindstorms are options)

3) Real Project Start a real project which may take some time. Use proper source control, and make a point to have a schedule. Run this project like a real project, if nothing else its good experience having to deal with the tools.

Obviously you need to adjust this for each person. The most important thing I've found is to make even the first simple apps apply to what the person is interested in.

Some projects:

  • Tetris
  • Text file based blog engine
  • More advanced robotics work

Regular expression that matches valid IPv6 addresses

A simple regex that will match, but I wouldn't recommend for validation of any sort is this:


Note this matches compression anywhere in the address, though it won't match the loopback address ::1. I find this a reasonable compromise in order to keep the regex simple.

I successfully use this in iTerm2 smart selection rules to quad-click IPv6 addresses.

Switch between python 2.7 and python 3.5 on Mac OS X

I already had python3 installed(via miniconda3) and needed to install python2 alongside in that case brew install python won't install python2, so you would need brew install python@2 .

Now alias python2 refers to python2.x from /usr/bin/python

and alias python3 refers to python3.x from /Users/ishandutta2007/miniconda3/bin/python

and alias python refers to python3 by default.

Now to use python as alias for python2, I added the following to .bashrc file

alias python='/usr/bin/python'.

To go back to python3 as default just remove this line when required.

Background thread with QThread in PyQt

I created a little example that shows 3 different and simple ways of dealing with threads. I hope it will help you find the right approach to your problem.

import sys
import time

from PyQt5.QtCore import (QCoreApplication, QObject, QRunnable, QThread,
                          QThreadPool, pyqtSignal)

# Subclassing QThread
class AThread(QThread):

    def run(self):
        count = 0
        while count < 5:
            print("A Increasing")
            count += 1

# Subclassing QObject and using moveToThread
class SomeObject(QObject):

    finished = pyqtSignal()

    def long_running(self):
        count = 0
        while count < 5:
            print("B Increasing")
            count += 1

# Using a QRunnable
# Note that a QRunnable isn't a subclass of QObject and therefore does
# not provide signals and slots.
class Runnable(QRunnable):

    def run(self):
        count = 0
        app = QCoreApplication.instance()
        while count < 5:
            print("C Increasing")
            count += 1

def using_q_thread():
    app = QCoreApplication([])
    thread = AThread()

def using_move_to_thread():
    app = QCoreApplication([])
    objThread = QThread()
    obj = SomeObject()

def using_q_runnable():
    app = QCoreApplication([])
    runnable = Runnable()

if __name__ == "__main__":

Recommended way of making React component/div draggable

I've updated solution to React 16 / ES6 with enhancements like touch handling and snapping to a grid which is what I need for a game. Snapping to a grid alleviates the performance issues.

import React from 'react';
import ReactDOM from 'react-dom';
import PropTypes from 'prop-types';

class Draggable extends React.Component {
    constructor(props) {
        this.state = {
            relX: 0,
            relY: 0,
            x: props.x,
            y: props.y
        this.gridX = props.gridX || 1;
        this.gridY = props.gridY || 1;
        this.onMouseDown = this.onMouseDown.bind(this);
        this.onMouseMove = this.onMouseMove.bind(this);
        this.onMouseUp = this.onMouseUp.bind(this);
        this.onTouchStart = this.onTouchStart.bind(this);
        this.onTouchMove = this.onTouchMove.bind(this);
        this.onTouchEnd = this.onTouchEnd.bind(this);

    static propTypes = {
        onMove: PropTypes.func,
        onStop: PropTypes.func,
        x: PropTypes.number.isRequired,
        y: PropTypes.number.isRequired,
        gridX: PropTypes.number,
        gridY: PropTypes.number

    onStart(e) {
        const ref = ReactDOM.findDOMNode(this.handle);
        const body = document.body;
        const box = ref.getBoundingClientRect();
            relX: e.pageX - (box.left + body.scrollLeft - body.clientLeft),
            relY: e.pageY - ( + body.scrollTop - body.clientTop)

    onMove(e) {
        const x = Math.trunc((e.pageX - this.state.relX) / this.gridX) * this.gridX;
        const y = Math.trunc((e.pageY - this.state.relY) / this.gridY) * this.gridY;
        if (x !== this.state.x || y !== this.state.y) {
            this.props.onMove && this.props.onMove(this.state.x, this.state.y);

    onMouseDown(e) {
        if (e.button !== 0) return;
        document.addEventListener('mousemove', this.onMouseMove);
        document.addEventListener('mouseup', this.onMouseUp);

    onMouseUp(e) {
        document.removeEventListener('mousemove', this.onMouseMove);
        document.removeEventListener('mouseup', this.onMouseUp);
        this.props.onStop && this.props.onStop(this.state.x, this.state.y);

    onMouseMove(e) {

    onTouchStart(e) {
        document.addEventListener('touchmove', this.onTouchMove, {passive: false});
        document.addEventListener('touchend', this.onTouchEnd, {passive: false});

    onTouchMove(e) {

    onTouchEnd(e) {
        document.removeEventListener('touchmove', this.onTouchMove);
        document.removeEventListener('touchend', this.onTouchEnd);
        this.props.onStop && this.props.onStop(this.state.x, this.state.y);

    render() {
        return <div
                position: 'absolute',
                left: this.state.x,
                top: this.state.y,
                touchAction: 'none'
            ref={(div) => { this.handle = div; }}

export default Draggable;

Jenkins: Cannot define variable in pipeline stage

You are using a Declarative Pipeline which requires a script-step to execute Groovy code. This is a huge difference compared to the Scripted Pipeline where this is not necessary.

The official documentation says the following:

The script step takes a block of Scripted Pipeline and executes that in the Declarative Pipeline.

pipeline {
   agent none
   stages {
       stage("first") {
           script {
               def foo = "foo" 
               sh "echo ${foo}"

com.sun.jdi.InvocationException occurred invoking method

In my case it was due to the object reference getting stale. I was automating my application using selenium webdriver, so i type something into a text box and then it navigates to another page, so while i come back on the previous page , that object gets stale. So this was causing the exception, I handled it by again initialising the elements - PageFactory.initElements(driver, Test.class;

Error : Program type already present:$Behavior


implementation ''

Don't use like

implementation ''

It may give you an error and don't use an older version than this.

or event don't do like this

implementation ''
implementation '' 

etc... numbers of libraries and then

implementation ''

the same library but it has a different version, it can give you an error.

"Could not get any response" response when using postman with subdomain

Postman for Linux Version 6.7.1 - Ubuntu 18.04 - linux 4.15.0-43-generic / x64

I had the same problem and by chance I replaced http://localhost with and everything worked.

My etc/hosts had the proper entries for localhost and https://localhost requests always worked as expected.

I have no clue why changing localhost for http with solved the issue.

Is it a good idea to index datetime field in mysql?

Here author performed tests showed that integer unix timestamp is better than DateTime. Note, he used MySql. But I feel no matter what DB engine you use comparing integers are slightly faster than comparing dates so int index is better than DateTime index. Take T1 - time of comparing 2 dates, T2 - time of comparing 2 integers. Search on indexed field takes approximately O(log(rows)) time because index based on some balanced tree - it may be different for different DB engines but anyway Log(rows) is common estimation. (if you not use bitmask or r-tree based index). So difference is (T2-T1)*Log(rows) - may play role if you perform your query oftenly.

how to access parent window object using jquery?

Here is a more literal answer (parent window as opposed to opener) to the original question that can be used within an iframe, assuming the domain name in the iframe matches that of the parent window:


How to get a list of installed android applications and pick one to run

Clean solution that filter successfuly out system apps

The idea behind this solution is that the main activity of every system app does not have a custom activity icon. This method gives me an excellent result:

 public static Set<PackageInfo> getInstalledApps(Context ctx) {
    final PackageManager packageManager = ctx.getPackageManager();

    final List<PackageInfo> allInstalledPackages = packageManager.getInstalledPackages(PackageManager.GET_META_DATA);
    final Set<PackageInfo> filteredPackages = new HashSet();

    Drawable defaultActivityIcon = packageManager.getDefaultActivityIcon();

    for(PackageInfo each : allInstalledPackages) {
        if(ctx.getPackageName().equals(each.packageName)) {
            continue;  // skip own app

        try {
            // add only apps with application icon
            Intent intentOfStartActivity = packageManager.getLaunchIntentForPackage(each.packageName);
            if(intentOfStartActivity == null)

            Drawable applicationIcon = packageManager.getActivityIcon(intentOfStartActivity);
            if(applicationIcon != null && !defaultActivityIcon.equals(applicationIcon)) {
        } catch (PackageManager.NameNotFoundException e) {
            Log.i("MyTag", "Unknown package name " + each.packageName);

    return filteredPackages;

Rotate axis text in python matplotlib

import pylab as pl
pl.xticks(rotation = 90)

How to move all HTML element children to another parent using JavaScript?

If you not use - in id's names then you can do this

#newParent { color: red }
<div id="oldParent">_x000D_
    Hello World_x000D_
<div id="newParent"></div>

Python: how to capture image from webcam on click using OpenCV

Here is a simple program that displays the camera feed in a cv2.namedWindow and will take a snapshot when you hit SPACE. It will also quit if you hit ESC.

import cv2

cam = cv2.VideoCapture(0)


img_counter = 0

while True:
    ret, frame =
    if not ret:
        print("failed to grab frame")
    cv2.imshow("test", frame)

    k = cv2.waitKey(1)
    if k%256 == 27:
        # ESC pressed
        print("Escape hit, closing...")
    elif k%256 == 32:
        # SPACE pressed
        img_name = "opencv_frame_{}.png".format(img_counter)
        cv2.imwrite(img_name, frame)
        print("{} written!".format(img_name))
        img_counter += 1



I think this should answer your question for the most part. If there is any line of it that you don't understand let me know and I'll add comments.

If you need to grab multiple images per press of the SPACE key, you will need an inner loop or perhaps just make a function that grabs a certain number of images.

Note that the key events are from the cv2.namedWindow so it has to have focus.

Find indices of elements equal to zero in a NumPy array

I would do it the following way:

>>> x = np.array([[1,0,0], [0,2,0], [1,1,0]])
>>> x
array([[1, 0, 0],
       [0, 2, 0],
       [1, 1, 0]])
>>> np.nonzero(x)
(array([0, 1, 2, 2]), array([0, 1, 0, 1]))

# if you want it in coordinates
>>> x[np.nonzero(x)]
array([1, 2, 1, 1])
>>> np.transpose(np.nonzero(x))
array([[0, 0],
       [1, 1],
       [2, 0],
       [2, 1])

Fetch: reject promise and catch the error if status is not OK?

For me, fny answers really got it all. since fetch is not throwing error, we need to throw/handle the error ourselves. Posting my solution with async/await. I think it's more strait forward and readable

Solution 1: Not throwing an error, handle the error ourselves

  async _fetch(request) {
    const fetchResult = await fetch(request); //Making the req
    const result = await fetchResult.json(); // parsing the response

    if (fetchResult.ok) {
      return result; // return success object

    const responseError = {
      type: 'Error',
      message: result.message || 'Something went wrong',
      data: || '',
      code: result.code || '',

    const error = new Error(); = responseError;

    return (error);

Here if we getting an error, we are building an error object, plain JS object and returning it, the con is that we need to handle it outside. How to use:

  const userSaved = await apiCall(data); // calling fetch
  if (userSaved instanceof Error) {
    debug.log('Failed saving user', userSaved); // handle error

  debug.log('Success saving user', userSaved); // handle success

Solution 2: Throwing an error, using try/catch

async _fetch(request) {
    const fetchResult = await fetch(request);
    const result = await fetchResult.json();

    if (fetchResult.ok) {
      return result;

    const responseError = {
      type: 'Error',
      message: result.message || 'Something went wrong',
      data: || '',
      code: result.code || '',

    let error = new Error();
    error = { ...error, ...responseError };
    throw (error);

Here we are throwing and error that we created, since Error ctor approve only string, Im creating the plain Error js object, and the use will be:

  try {
    const userSaved = await apiCall(data); // calling fetch
    debug.log('Success saving user', userSaved); // handle success
  } catch (e) {
    debug.log('Failed saving user', userSaved); // handle error

Solution 3: Using customer error

  async _fetch(request) {
    const fetchResult = await fetch(request);
    const result = await fetchResult.json();

    if (fetchResult.ok) {
      return result;

    throw new ClassError(result.message,, result.code);


class ClassError extends Error {

  constructor(message = 'Something went wrong', data = '', code = '') {
    this.message = message; = data;
    this.code = code;


Hope it helped.

Convert a string to a double - is this possible?

For arbitrary precision mathematics PHP offers the Binary Calculator which supports numbers of any size and precision, represented as strings.

$s = '1234.13';
$double = bcadd($s,'0',2);

PHP: bcadd

How do you give iframe 100% height

The problem with iframes not getting 100% height is not because they're unwieldy. The problem is that for them to get 100% height they need their parents to have 100% height. If one of the iframe's parents is not 100% tall the iframe won't be able to go beyond that parent's height.

So the best possible solution would be:

html, body, iframe { height: 100%; }

…given the iframe is directly under body. If the iframe has a parent between itself and the body, the iframe will still get the height of its parent. One must explicitly set the height of every parent to 100% as well (if that's what one wants).

Tested in:

Chrome 30, Firefox 24, Safari 6.0.5, Opera 16, IE 7, 8, 9 and 10

PS: I don't mean to be picky but the solution marked as correct doesn't work on Firefox 24 at the time of this writing, but worked on Chrome 30. Haven't tested on other browsers though. I came across the error on Firefox because the page I was testing had very little content... It could be it's my meager markup or the CSS reset altering the output, but if I experienced this error I guess the accepted answer doesn't work in every situation.

Update 2021

@Zeni suggested this in 2015:

iframe { height: 100vh }

...and indeed it does the trick!

Careful with positioning as it can potentially break the effect. Test thoroughly, you might not need positioning depending of what you're trying to achieve.

How to change UIButton image in Swift

Swift 5 and ensures the image scales to the size of the button but stays within the buttons bounds.

yourButton.clipsToBounds = true
yourButton.contentMode = .scaleAspectFill

// Use setBackgroundImage or setImage
yourButton.setBackgroundImage(UIImage(named: "yourImage"), for: .normal)

Trying to get property of non-object - CodeIgniter

To access the elements in the array, use array notation: $product['prodname']

$product->prodname is object notation, which can only be used to access object attributes and methods.

How to test if string exists in file with Bash?

If I understood your question correctly, this should do what you need.

  1. you can specifiy the directory you would like to add through $check variable
  2. if the directory is already in the list, the output is "dir already listed"
  3. if the directory is not yet in the list, it is appended to my_list.txt

In one line: check="/tmp/newdirectory"; [[ -n $(grep "^$check\$" my_list.txt) ]] && echo "dir already listed" || echo "$check" >> my_list.txt

initialize a vector to zeros C++/C++11

You don't need initialization lists for that:

std::vector<int> vector1(length, 0);
std::vector<double> vector2(length, 0.0);

Object passed as parameter to another class, by value or reference?

"Objects" are NEVER passed in C# -- "objects" are not values in the language. The only types in the language are primitive types, struct types, etc. and reference types. No "object types".

The types Object, MyClass, etc. are reference types. Their values are "references" -- pointers to objects. Objects can only be manipulated through references -- when you do new on them, you get a reference, the . operator operates on a reference; etc. There is no way to get a variable whose value "is" an object, because there are no object types.

All types, including reference types, can be passed by value or by reference. A parameter is passed by reference if it has a keyword like ref or out. The SetObject method's obj parameter (which is of a reference type) does not have such a keyword, so it is passed by value -- the reference is passed by value.

VBScript to send email without running Outlook

You can send email without Outlook in VBScript using the CDO.Message object. You will need to know the address of your SMTP server to use this:

Set MyEmail=CreateObject("CDO.Message")

MyEmail.From="[email protected]"
MyEmail.To="[email protected]"
MyEmail.TextBody="Testing one two three."

MyEmail.Configuration.Fields.Item ("")=2

'SMTP Server
MyEmail.Configuration.Fields.Item ("")=""

'SMTP Port
MyEmail.Configuration.Fields.Item ("")=25 


set MyEmail=nothing

If your SMTP server requires a username and password then paste these lines in above the MyEmail.Configuration.Fields.Update line:

'SMTP Auth (For Windows Auth set this to 2)
MyEmail.Configuration.Fields.Item ("")=1
MyEmail.Configuration.Fields.Item ("")="username" 
MyEmail.Configuration.Fields.Item ("")="password"

More information on using CDO to send email with VBScript can be found on the link below:

Your project contains error(s), please fix it before running it

Is there a way to ignore existing errors in project. Something similar what eclipse allows in case of java projects.

In my case the errors exist in jni directory. The errors are shown even though ndk-buid succeeds. So all i want to do is to ignore the errors reported by eclipse.

If the errors are indeed errors then i should get unresolved symbols during ndk-build.

I have ensured standard android includes are there in include path.

Also my project is of type android/c/c++.

I have two builders associated with the project 1. statndard android builder 2. custom ndk builder that ive explicitly created.

List of IP Space used by Facebook

The list from 2020-05-23 is:

The method to fetch this list is already documented on Facebook's Developer site, you can make a whois call to see all IPs assigned to Facebook:

whois -h -- '-i origin AS32934' | grep ^route

Get human readable version of file size?

This feature if available in Boltons which is a very handy library to have for most projects.

>>> bytes2human(128991)
>>> bytes2human(100001221)
>>> bytes2human(0, 2)

Only read selected columns

To read a specific set of columns from a dataset you, there are several other options:

1) With freadfrom the data.table-package:

You can specify the desired columns with the select parameter from fread from the data.table package. You can specify the columns with a vector of column names or column numbers.

For the example dataset:

dat <- fread("data.txt", select = c("Year","Jan","Feb","Mar","Apr","May","Jun"))
dat <- fread("data.txt", select = c(1:7))

Alternatively, you can use the drop parameter to indicate which columns should not be read:

dat <- fread("data.txt", drop = c("Jul","Aug","Sep","Oct","Nov","Dec"))
dat <- fread("data.txt", drop = c(8:13))

All result in:

> data
  Year Jan Feb Mar Apr May Jun
1 2009 -41 -27 -25 -31 -31 -39
2 2010 -41 -27 -25 -31 -31 -39
3 2011 -21 -27  -2  -6 -10 -32

UPDATE: When you don't want fread to return a data.table, use the data.table = FALSE-parameter, e.g.: fread("data.txt", select = c(1:7), data.table = FALSE)

2) With read.csv.sql from the sqldf-package:

Another alternative is the read.csv.sql function from the sqldf package:

dat <- read.csv.sql("data.txt",
                    sql = "select Year,Jan,Feb,Mar,Apr,May,Jun from file",
                    sep = "\t")

3) With the read_*-functions from the readr-package:

dat <- read_table("data.txt",
                  col_types = cols_only(Year = 'i', Jan = 'i', Feb = 'i', Mar = 'i',
                                        Apr = 'i', May = 'i', Jun = 'i'))
dat <- read_table("data.txt",
                  col_types = list(Jul = col_skip(), Aug = col_skip(), Sep = col_skip(),
                                   Oct = col_skip(), Nov = col_skip(), Dec = col_skip()))
dat <- read_table("data.txt", col_types = 'iiiiiii______')

From the documentation an explanation for the used characters with col_types:

each character represents one column: c = character, i = integer, n = number, d = double, l = logical, D = date, T = date time, t = time, ? = guess, or _/- to skip the column

Converting String to Int using try/except in Python

It is important to be specific about what exception you're trying to catch when using a try/except block.

string = "abcd"
    string_int = int(string)
except ValueError:
    # Handle the exception
    print('Please enter an integer')

Try/Excepts are powerful because if something can fail in a number of different ways, you can specify how you want the program to react in each fail case.

CSS @font-face not working with Firefox, but working with Chrome and IE


Firefox comes with a very strict "file uri origin" (file:///) policy by default: to have it to behave just as other browsers, go to about:config, filter by fileuri and toggle the following preference:


Set it to false and you should be able to load local font resources across different path levels.


As per my comment below, and you are experiencing this problem after deploying your site, you could try to add an additional header to see if your problem configures itself as a cross domain issue: it shouldn't, since you are specifying relative paths, but i would give it a try anyway: in your .htaccess file, specify you want to send an additional header for each .ttf/.otf/.eot file being requested:

<FilesMatch "\.(ttf|otf|eot)$">
    <IfModule mod_headers.c>
        Header set Access-Control-Allow-Origin "*"

Frankly, I wouldn't expect it to make any difference, but it's so simple it's worth trying: else try to use base64 encoding for your font typeface, ugly but it may works too.

A nice recap is available here

get the margin size of an element with jquery

The CSS tag 'margin' is actually a shorthand for the four separate margin values, top/left/bottom/right. Use css('marginTop'), etc. - note they will have 'px' on the end if you have specified them that way.

Use parseInt() around the result to turn it in to the number value.

NB. As noted by Omaty, the order of the shorthand 'margin' tag is: top right bottom left - the above list was not written in a way intended to be the list order, just a list of that specified in the tag.

OpenCV Python rotate image by X degrees around specific point

Here's an example for rotating about an arbitrary point (x,y) using only openCV

def rotate_about_point(x, y, degree, image):
    rot_mtx = cv.getRotationMatrix2D((x, y), angle, 1)
    abs_cos = abs(rot_mtx[0, 0])
    abs_sin = abs(rot_mtx[0, 1])
    rot_wdt = int(frm_hgt * abs_sin + frm_wdt * abs_cos)
    rot_hgt = int(frm_hgt * abs_cos + frm_wdt * abs_sin)
    rot_mtx += np.asarray([[0, 0, -lftmost_x],
                           [0, 0, -topmost_y]])
    rot_img = cv.warpAffine(image, rot_mtx, (rot_wdt, rot_hgt),
    return rot_img

Is it possible to declare a public variable in vba and assign a default value?

You can define the variable in General Declarations and then initialise it in the first event that fires in your environment.

Alternatively, you could create yourself a class with the relevant properties and initialise them in the Initialise method

Passing an integer by reference in Python

class Obj:
  def __init__(self,a):
    self.value = a
  def sum(self, a):
    self.value += a
a = Obj(1)
b = a
print(a.value, b.value)// 2 2

Using "like" wildcard in prepared statement

We can use the CONCAT SQL function.

PreparedStatement pstmt = con.prepareStatement(
      "SELECT * FROM analysis WHERE notes like CONCAT( '%',?,'%')";
pstmt.setString(1, notes);
ResultSet rs = pstmt.executeQuery();

This works perfectly for my case.

How do I remove a single file from the staging area (undo git add)?

If you make changes to many tracked files but only want to stage a few of them, doing a

git add .

isn't always favorable (or recommended)- as it stages all the tracked files (some cases where you want to keep changes only to yourself and don't want to stage them to the remote repository).

nor is it ideal doing a bunch of

git add path/to/file1 path/to/file2

if you have a lot of nested directories (which is the case in most projects) - gets annoying

That's when Git GUI is helpful (probably only time I use it). Just open Git GUI, it shows staged and unstaged file sections. Select the files from the staged section that you want to unstage and press

Ctrl+U (for windows)

to unstage them.

Deleting elements from std::set while iterating

If you run your program through valgrind, you'll see a bunch of read errors. In other words, yes, the iterators are being invalidated, but you're getting lucky in your example (or really unlucky, as you're not seeing the negative effects of undefined behavior). One solution to this is to create a temporary iterator, increment the temp, delete the target iterator, then set the target to the temp. For example, re-write your loop as follows:

std::set<int>::iterator it = numbers.begin();                               
std::set<int>::iterator tmp;                                                

// iterate through the set and erase all even numbers                       
for ( ; it != numbers.end(); )                                              
    int n = *it;                                                            
    if (n % 2 == 0)                                                         
        tmp = it;                                                           
        it = tmp;                                                           

How to get the filename without the extension from a path in Python?

But even when I import os, I am not able to call it path.basename. Is it possible to call it as directly as basename?

import os, and then use os.path.basename

importing os doesn't mean you can use without referring to os.

Jupyter Notebook not saving: '_xsrf' argument missing from post

The only solution worked for me was:

  1. I opened a new tab in chrome
  2. I pasted : http://localhost:8888/?token=......
  3. then I went to my original notebook and I was able to save it

A cron job for rails: best practices?

Both will work fine. I usually use script/runner.

Here's an example:

0 6 * * * cd /var/www/apps/your_app/current; ./script/runner --environment production 'EmailSubscription.send_email_subscriptions' >> /var/www/apps/your_app/shared/log/send_email_subscriptions.log 2>&1

You can also write a pure-Ruby script to do this if you load the right config files to connect to your database.

One thing to keep in mind if memory is precious is that script/runner (or a Rake task that depends on 'environment') will load the entire Rails environment. If you only need to insert some records into the database, this will use memory you don't really have to. If you write your own script, you can avoid this. I haven't actually needed to do this yet, but I am considering it.

How do you use the "WITH" clause in MySQL?

That feature is called a common table expression

You won't be able to do the exact thing in mySQL, the easiest thing would to probably make a view that mirrors that CTE and just select from the view. You can do it with subqueries, but that will perform really poorly. If you run into any CTEs that do recursion, I don't know how you'd be able to recreate that without using stored procedures.

EDIT: As I said in my comment, that example you posted has no need for a CTE, so you must have simplified it for the question since it can be just written as

SELECT article.*, userinfo.*, category.* FROM question
     INNER JOIN userinfo ON userinfo.user_userid=article.article_ownerid
     INNER JOIN category ON article.article_categoryid=category.catid
     WHERE article.article_isdeleted = 0
 ORDER BY article_date DESC Limit 1, 3

Go doing a GET request and building the Querystring

Using NewRequest just to create an URL is an overkill. Use the net/url package:

package main

import (

func main() {
    base, err := url.Parse("")
    if err != nil {

    // Path params
    base.Path += "this will get automatically encoded"

    // Query params
    params := url.Values{}
    params.Add("q", "this will get encoded as well")
    base.RawQuery = params.Encode() 

    fmt.Printf("Encoded URL is %q\n", base.String())


Solution for "Fatal error: Maximum function nesting level of '100' reached, aborting!" in PHP

I had the same problem and I resolved it like this:

  • Open MySQL my.ini file
  • In [mysqld] section, add the following line: innodb_force_recovery = 1
  • Save the file and try starting MySQL
  • Remove that line which you just added and Save

Read input numbers separated by spaces

int main() {
int sum = 0;
cout << "enter number" << endl;
int i = 0;
while (true) {
    cin >> i;
    sum += i;
    //cout << i << endl;
    if (cin.peek() == '\n') {

cout << "result: " << sum << endl;
return 0;

I think this code works, you may enter any int numbers and spaces, it will calculate the sum of input ints

Android, Java: HTTP POST Request

I used the following code to send HTTP POST from my android client app to C# desktop app on my server:

// Create a new HttpClient and Post Header
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("");

try {
    // Add your data
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
    nameValuePairs.add(new BasicNameValuePair("id", "12345"));
    nameValuePairs.add(new BasicNameValuePair("stringdata", "AndDev is Cool!"));
    httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

    // Execute HTTP Post Request
    HttpResponse response = httpclient.execute(httppost);

} catch (ClientProtocolException e) {
    // TODO Auto-generated catch block
} catch (IOException e) {
    // TODO Auto-generated catch block

I worked on reading the request from a C# app on my server (something like a web server little application). I managed to read request posted data using the following code:

server = new HttpListener();

HttpListenerContext context = server.GetContext();
HttpListenerContext context = obj as HttpListenerContext;
HttpListenerRequest request = context.Request;

StreamReader sr = new StreamReader(request.InputStream);
string str = sr.ReadToEnd();

What is the difference between String and StringBuffer in Java?

By printing the hashcode of the String/StringBuffer object after any append operation also prove, String object is getting recreated internally every time with new values rather than using the same String object.

public class MutableImmutable {

 * @param args
public static void main(String[] args) {
    System.out.println("String is immutable");
    String s = "test";
    for (int i = 0; i < 10; i++) {
        s += "tre";

    System.out.println("String Buffer is mutable");

    StringBuffer strBuf = new StringBuffer("test");
    for (int i = 0; i < 10; i++) {



Output: It prints object value along with its hashcode

    String is immutable
    String Buffer is mutable

Add object to ArrayList at specified index


The problem here is java creates an empty list when you called new ArrayList and 

while trying to add an element at specified position you got IndexOutOfBound , so the list should have some elements at their position.

Please try following

  Add an element to specified index of Java ArrayList Example
  This Java Example shows how to add an element at specified index of java
  ArrayList object using add method.

import java.util.ArrayList;

public class AddElementToSpecifiedIndexArrayListExample {

  public static void main(String[] args) {
    //create an ArrayList object
    ArrayList arrayList = new ArrayList();

    //Add elements to Arraylist

      To add an element at the specified index of ArrayList use
      void add(int index, Object obj) method.
      This method inserts the specified element at the specified index in the
    arrayList.add(1,"INSERTED ELEMENT");

      Please note that add method DOES NOT overwrites the element previously
      at the specified index in the list. It shifts the elements to right side
      and increasing the list size by 1.

    System.out.println("ArrayList contains...");
    //display elements of ArrayList
    for(int index=0; index < arrayList.size(); index++)


Output would be
ArrayList contains...


How to mock static methods in c# using MOQ framework?

Another option to transform the static method into a static Func or Action. For instance.

Original code:

    class Math
        public static int Add(int x, int y)
            return x + y;

You want to "mock" the Add method, but you can't. Change the above code to this:

        public static Func<int, int, int> Add = (x, y) =>
            return x + y;

Existing client code doesn't have to change (maybe recompile), but source stays the same.

Now, from the unit-test, to change the behavior of the method, just reassign an in-line function to it:

    public static void MyTest()
        Math.Add = (x, y) =>
            return 11;

Put whatever logic you want in the method, or just return some hard-coded value, depending on what you're trying to do.

This may not necessarily be something you can do each time, but in practice, I found this technique works just fine.

[edit] I suggest that you add the following Cleanup code to your Unit Test class:

    public void Cleanup()
        typeof(Math).TypeInitializer.Invoke(null, null);

Add a separate line for each static class. What this does is, after the unit test is done running, it resets all the static fields back to their original value. That way other unit tests in the same project will start out with the correct defaults as opposed your mocked version.

Resource interpreted as stylesheet but transferred with MIME type text/html (seems not related with web server)

I have the same exact problem and after a few minutes fooling around I deciphered that I missed to add the file extension to my header. so I changed the following line :

<link uic-remove rel="stylesheet" href="css/bahblahblah">


<link uic-remove rel="stylesheet" href="css/bahblahblah.css"> 

Retrieve last 100 lines logs

"tail" is command to display the last part of a file, using proper available switches helps us to get more specific output. the most used switch for me is -n and -f


tail [-F | -f | -r] [-q] [-b number | -c number | -n number] [file ...]


-n number : The location is number lines.

-f : The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the input. The -f option is ignored if the standard input is a pipe, but not if it is a FIFO.

Retrieve last 100 lines logs

To get last static 100 lines  
     tail -n 100 <file path>

To get real time last 100 lines
     tail -f -n 100 <file path>

strcpy() error in Visual studio 2012

For my problem, I removed the #include <glui.h> statement and it ran without a problem.

How can I render HTML from another file in a React component?

You could do it if template is a react component.


var React = require('react');

var Template = React.createClass({
    render: function(){
        return (<div>Mi HTML</div>);

module.exports = Template;


var React = require('react');
var ReactDOM = require('react-dom');
var injectTapEventPlugin = require("react-tap-event-plugin");
var Template = require('./Template');

//Needed for React Developer Tools
window.React = React;

//Needed for onTouchTap
//Can go away when react 1.0 release
//Check this repo:

var MainComponent = React.createClass({
    render: function() {

// Render the main app react component into the app div.
// For more details see:
  <MainComponent />,

And if you are using Material-UI, for compatibility use Material-UI Components, no normal inputs.

How to include !important in jquery

It is also possible to add more important properties:

inputObj.attr('style', 'color:black !important; background-color:#428bca !important;');

Write a number with two decimal places SQL Server

Use Str() Function. It takes three arguments(the number, the number total characters to display, and the number of decimal places to display

  Select Str(12345.6789, 12, 3)

displays: ' 12345.679' ( 3 spaces, 5 digits 12345, a decimal point, and three decimal digits (679). - it rounds if it has to truncate, (unless the integer part is too large for the total size, in which case asterisks are displayed instead.)

for a Total of 12 characters, with 3 to the right of decimal point.

Google Maps JavaScript API RefererNotAllowedMapError

For deeper nested pages

If you have a project in a folder for example or nested pages you can enter this in*/*

The important part being /*/*/* depending how far you need to go

It seems that the * will not match / or get into deeper paths..

This will give your full domain access, well unless you have deeper nesting than that..

BigDecimal equals() versus compareTo()

I believe that the correct answer would be to make the two numbers (BigDecimals), have the same scale, then we can decide about their equality. For example, are these two numbers equal?

1.00001 and 1.00002

Well, it depends on the scale. On the scale 5 (5 decimal points), no they are not the same. but on smaller decimal precisions (scale 4 and lower) they are considered equal. So I suggest make the scale of the two numbers equal and then compare them.

Android Support Design TabLayout: Gravity Center and Mode Scrollable

Very simple example and it always works.

 * Setup stretch and scrollable TabLayout.
 * The TabLayout initial parameters in layout must be:
 * android:layout_width="wrap_content"
 * app:tabMaxWidth="0dp"
 * app:tabGravity="fill"
 * app:tabMode="fixed"
 * @param context   your Context
 * @param tabLayout your TabLayout
public static void setupStretchTabLayout(Context context, TabLayout tabLayout) { -> {

        ViewGroup.LayoutParams params = tabLayout.getLayoutParams();
        if (params.width == ViewGroup.LayoutParams.MATCH_PARENT) { // is already set up for stretch

        int deviceWidth = context.getResources()

        if (tabLayout.getWidth() < deviceWidth) {
            params.width = ViewGroup.LayoutParams.MATCH_PARENT;
        } else {
            params.width = ViewGroup.LayoutParams.WRAP_CONTENT;



How can I show an element that has display: none in a CSS rule?

try setting the display to block in your javascript instead of a blank value.

How can I replace every occurrence of a String in a file with PowerShell?

I found a little known but amazingly cool way to do it from Payette's Windows Powershell in Action. You can reference files like variables, similar to $env:path, but you need to add the curly braces.

${c:file.txt} = ${c:file.txt} -replace 'oldvalue','newvalue'

Stop a youtube video with jquery?

for those who are looking javascript solution

let iframeDiv = document.getElementById('demoVideo');
                        let video = iframeDiv.src;
                        iframeDiv.src = "";
                        iframeDiv.src = video;

It perfectly worked for me just put id='demoVideo' in your iframe tag and you are good to go :)

Keras, how do I predict after I trained a model?

You must use the same Tokenizer you used to build your model!

Else this will give different vector to each word.

Then, I am using:

phrase = "not good"
tokens = myTokenizer.texts_to_matrix([phrase])


Getting ssh to execute a command in the background on target machine

I think this is what you need: At first you need to install sshpass on your machine. then you can write your own script:

while read pass port user ip; do
sshpass -p$pass ssh -p $port $user@$ip <<ENDSSH1
done <<____HERE
    PASS    PORT    USER    IP
      .      .       .       .
      .      .       .       .
      .      .       .       .
    PASS    PORT    USER    IP    

How to access site running apache server over lan without internet connection

Open httpd.conf of Apache server (backup first) Look for the the following : Listen

Change the line to

Listen *:80

Still in httpd.conf, look for the following (or similar):

<Directory />
    Options FollowSymLinks
    AllowOverride None
    Order deny,allow
    Allow from all
    Deny from all

Change this block to :

<Directory />
    Options FollowSymLinks
    AllowOverride None
    Order deny,allow
    Allow from all
    #Deny from all

Save httpd.conf and restart apache

Open port 80 of the server such that everyone can access your server.

Open Control Panel >> System and Security >> Windows Firewall then click on “Advance Setting” and then select “Inbound Rules” from the left panel and then click on “Add Rule…”. Select “PORT” as an option from the list and then in the next screen select “TCP” protocol and enter port number “80” under “Specific local port” then click on the ”Next” button and select “Allow the Connection” and then give the general name and description to this port and click Done.

Restart WAMP and access your machine in LAN or WAN.

Python: "TypeError: __str__ returned non-string" but still prints to output?

Method __str__ should return string, not print.

def __str__(self):
    return 'Memo={0}, Tag={1}'.format(self.memo, self.tags)

How to secure database passwords in PHP?

Your choices are kind of limited as as you say you need the password to access the database. One general approach is to store the username and password in a seperate configuration file rather than the main script. Then be sure to store that outside the main web tree. That was if there is a web configuration problem that leaves your php files being simply displayed as text rather than being executed you haven't exposed the password.

Other than that you are on the right lines with minimal access for the account being used. Add to that

  • Don't use the combination of username/password for anything else
  • Configure the database server to only accept connections from the web host for that user (localhost is even better if the DB is on the same machine) That way even if the credentials are exposed they are no use to anyone unless they have other access to the machine.
  • Obfuscate the password (even ROT13 will do) it won't put up much defense if some does get access to the file, but at least it will prevent casual viewing of it.


Interesting 'takes exactly 1 argument (2 given)' Python error

Yes, when you invoke e.extractAll(foo), Python munges that into extractAll(e, foo).


the special thing about methods is that the object is passed as the first argument of the function. In our example, the call x.f() is exactly equivalent to MyClass.f(x). In general, calling a method with a list of n arguments is equivalent to calling the corresponding function with an argument list that is created by inserting the method’s object before the first argument.

Emphasis added.

Adb over wireless without usb cable at all for not rooted phones

type in Windows cmd.exe

    cd %userprofile%\.android
    copy adb_keys

copy the file adb_keys to your phone folder /data/misc/adb. Reboot the phone. RSA Key is now authorized.

from: How to solve ADB device unauthorized in Android ADB host device?

now follow the instructions for adb connect, or use any app for preparing. i prefer ADB over WIFI Widget from Mehdy Bohlool, it works without root.

from: How can I connect to Android with ADB over TCP?

How to dynamic new Anonymous Class?

Anonymous types are just regular types that are implicitly declared. They have little to do with dynamic.

Now, if you were to use an ExpandoObject and reference it through a dynamic variable, you could add or remove fields on the fly.


Sure you can: just cast it to IDictionary<string, object>. Then you can use the indexer.

You use the same casting technique to iterate over the fields:

dynamic employee = new ExpandoObject();
employee.Name = "John Smith";
employee.Age = 33;

foreach (var property in (IDictionary<string, object>)employee)
    Console.WriteLine(property.Key + ": " + property.Value);
// This code example produces the following output:
// Name: John Smith
// Age: 33

The above code and more can be found by clicking on that link.

how to convert .java file to a .class file

As the others stated : it's by compiling. You can use the javac command, but I'f you're new at java, I suggest you use a software for compiling your code (and IDE) such as Eclipse and it will do the job for you.

How to drop rows of Pandas DataFrame whose value in a certain column is NaN

This question is already resolved, but...

...also consider the solution suggested by Wouter in his original comment. The ability to handle missing data, including dropna(), is built into pandas explicitly. Aside from potentially improved performance over doing it manually, these functions also come with a variety of options which may be useful.

In [24]: df = pd.DataFrame(np.random.randn(10,3))

In [25]: df.iloc[::2,0] = np.nan; df.iloc[::4,1] = np.nan; df.iloc[::3,2] = np.nan;

In [26]: df
          0         1         2
0       NaN       NaN       NaN
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
3  0.672201  0.964789       NaN
4       NaN       NaN  0.050742
5 -1.250970  0.030561 -2.678622
6       NaN  1.036043       NaN
7  0.049896 -0.308003  0.823295
8       NaN       NaN  0.637482
9 -0.310130  0.078891       NaN

In [27]: df.dropna()     #drop all rows that have any NaN values
          0         1         2
1  2.677677 -1.466923 -0.750366
5 -1.250970  0.030561 -2.678622
7  0.049896 -0.308003  0.823295

In [28]: df.dropna(how='all')     #drop only if ALL columns are NaN
          0         1         2
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
3  0.672201  0.964789       NaN
4       NaN       NaN  0.050742
5 -1.250970  0.030561 -2.678622
6       NaN  1.036043       NaN
7  0.049896 -0.308003  0.823295
8       NaN       NaN  0.637482
9 -0.310130  0.078891       NaN

In [29]: df.dropna(thresh=2)   #Drop row if it does not have at least two values that are **not** NaN
          0         1         2
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
3  0.672201  0.964789       NaN
5 -1.250970  0.030561 -2.678622
7  0.049896 -0.308003  0.823295
9 -0.310130  0.078891       NaN

In [30]: df.dropna(subset=[1])   #Drop only if NaN in specific column (as asked in the question)
          0         1         2
1  2.677677 -1.466923 -0.750366
2       NaN  0.798002 -0.906038
3  0.672201  0.964789       NaN
5 -1.250970  0.030561 -2.678622
6       NaN  1.036043       NaN
7  0.049896 -0.308003  0.823295
9 -0.310130  0.078891       NaN

There are also other options (See docs at, including dropping columns instead of rows.

Pretty handy!

Encapsulation vs Abstraction?

Abstraction is the concept of describing something in simpler terms, i.e abstracting away the details, in order to focus on what is important (This is also seen in abstract art, for example, where the artist focuses on the building blocks of images, such as colour or shapes). The same idea translates to OOP by using an inheritance hierarchy, where more abstract concepts are at the top and more concrete ideas, at the bottom, build upon their abstractions. At its most abstract level there is no implementation details at all and perhaps very few commonalities, which are added as the abstraction decreases.

As an example, at the top might be an interface with a single method, then the next level, provides several abstract classes, which may or may not fill in some of the details about the top level, but branches by adding their own abstract methods, then for each of these abstract classes are concrete classes providing implementations of all the remaining methods.

Encapsulation is a technique. It may or may not be for aiding in abstraction, but it is certainly about information hiding and/or organisation. It demands data and functions be grouped in some way - of course good OOP practice demands that they should be grouped by abstraction. However, there are other uses which just aid in maintainability etc.

Fatal error: Call to undefined function sqlsrv_connect()

i have same this because in httpd.conf in apache PHPIniDir D:/wamp/bin/php/php5.5.12 that was incorrect

Normalizing images in OpenCV

The other answers normalize an image based on the entire image. But if your image has a predominant color (such as black), it will mask out the features that you're trying to enhance since it will not be as pronounced. To get around this limitation, we can normalize the image based on a subsection region of interest (ROI). Essentially we will normalize based on the section of the image that we want to enhance instead of equally treating each pixel with the same weight. Take for instance this earth image:

Input image -> Normalization based on entire image

If we want to enhance the clouds by normalizing based on the entire image, the result will not be very sharp and will be over saturated due to the black background. The features to enhance are lost. So to obtain a better result we can crop a ROI, normalize based on the ROI, and then apply the normalization back onto the original image. Say we crop the ROI highlighted in green:

This gives us this ROI

The idea is to calculate the mean and standard deviation of the ROI and then clip the frame based on the lower and upper range. In addition, we could use an offset to dynamically adjust the clip intensity. From here we normalize the original image to this new range. Here's the result:

Before -> After


import cv2
import numpy as np

# Load image as grayscale and crop ROI
image = cv2.imread('1.png', 0)
x, y, w, h = 364, 633, 791, 273
ROI = image[y:y+h, x:x+w]

# Calculate mean and STD
mean, STD  = cv2.meanStdDev(ROI)

# Clip frame to lower and upper STD
offset = 0.2
clipped = np.clip(image, mean - offset*STD, mean + offset*STD).astype(np.uint8)

# Normalize to range
result = cv2.normalize(clipped, clipped, 0, 255, norm_type=cv2.NORM_MINMAX)

cv2.imshow('image', image)
cv2.imshow('ROI', ROI)
cv2.imshow('result', result)

The difference between normalizing based on the entire image vs a specific section of the ROI can be visualized by applying a heatmap to the result. Notice the difference on how the clouds are defined.

Input image -> heatmap

Normalized on entire image -> heatmap

Normalized on ROI -> heatmap

Heatmap code

import matplotlib.pyplot as plt
import numpy as np
import cv2

image = cv2.imread('result.png', 0)
colormap = plt.get_cmap('inferno')
heatmap = (colormap(image) * 2**16).astype(np.uint16)[:,:,:3]
heatmap = cv2.cvtColor(heatmap, cv2.COLOR_RGB2BGR)

cv2.imshow('image', image)
cv2.imshow('heatmap', heatmap)

Note: The ROI bounding box coordinates were obtained using how to get ROI Bounding Box Coordinates without Guess & Check and heatmap code was from how to convert a grayscale image to heatmap image with Python OpenCV

How to insert multiple rows from array using CodeIgniter framework?

Although it is too late to answer this question. Here are my answer on the same.

If you are using CodeIgniter then you can use inbuilt methods defined in query_builder class.


Generates an insert string based on the data you supply, and runs the query. You can either pass an array or an object to the function. Here is an example using an array:

$data = array(
            'title' => 'My title',
            'name' => 'My Name',
            'date' => 'My date'
            'title' => 'Another title',
            'name' => 'Another Name',
            'date' => 'Another date'

$this->db->insert_batch('mytable', $data);
// Produces: INSERT INTO mytable (title, name, date) VALUES ('My title', 'My name', 'My date'),  ('Another title', 'Another name', 'Another date')

The first parameter will contain the table name, the second is an associative array of values.

You can find more details about query_builder here

How can I use a DLL file from Python?

For ease of use, ctypes is the way to go.

The following example of ctypes is from actual code I've written (in Python 2.5). This has been, by far, the easiest way I've found for doing what you ask.

import ctypes

# Load DLL into memory.

hllDll = ctypes.WinDLL ("c:\\PComm\\ehlapi32.dll")

# Set up prototype and parameters for the desired function call.

hllApiProto = ctypes.WINFUNCTYPE (
    ctypes.c_int,      # Return type.
    ctypes.c_void_p,   # Parameters 1 ...
    ctypes.c_void_p)   # ... thru 4.
hllApiParams = (1, "p1", 0), (1, "p2", 0), (1, "p3",0), (1, "p4",0),

# Actually map the call ("HLLAPI(...)") to a Python name.

hllApi = hllApiProto (("HLLAPI", hllDll), hllApiParams)

# This is how you can actually call the DLL function.
# Set up the variables and call the Python name with them.

p1 = ctypes.c_int (1)
p2 = ctypes.c_char_p (sessionVar)
p3 = ctypes.c_int (1)
p4 = ctypes.c_int (0)
hllApi (ctypes.byref (p1), p2, ctypes.byref (p3), ctypes.byref (p4))

The ctypes stuff has all the C-type data types (int, char, short, void*, and so on) and can pass by value or reference. It can also return specific data types although my example doesn't do that (the HLL API returns values by modifying a variable passed by reference).

In terms of the specific example shown above, IBM's EHLLAPI is a fairly consistent interface.

All calls pass four void pointers (EHLLAPI sends the return code back through the fourth parameter, a pointer to an int so, while I specify int as the return type, I can safely ignore it) as per IBM's documentation here. In other words, the C variant of the function would be:

int hllApi (void *p1, void *p2, void *p3, void *p4)

This makes for a single, simple ctypes function able to do anything the EHLLAPI library provides, but it's likely that other libraries will need a separate ctypes function set up per library function.

The return value from WINFUNCTYPE is a function prototype but you still have to set up more parameter information (over and above the types). Each tuple in hllApiParams has a parameter "direction" (1 = input, 2 = output and so on), a parameter name and a default value - see the ctypes doco for details

Once you have the prototype and parameter information, you can create a Python "callable" hllApi with which to call the function. You simply create the needed variable (p1 through p4 in my case) and call the function with them.

Auto increment in MongoDB to store sequence of Unique User ID

The best way I found to make this to my purpose was to increment from the max value you have in the field and for that, I used the following syntax:

maxObj = db.CollectionName.aggregate([
    $group : { _id: '$item', maxValue: { $max: '$fieldName' } } 
fieldNextValue = maxObj.maxValue + 1;

$fieldName is the name of your field, but without the $ sign.

CollectionName is the name of your collection.

The reason I am not using count() is that the produced value could meet an existing value.

The creation of an enforcing unique index could make it safer:

db.CollectionName.createIndex( { "fieldName": 1 }, { unique: true } )

Using Service to run background and create notification

The question is relatively old, but I hope this post still might be relevant for others.

TL;DR: use AlarmManager to schedule a task, use IntentService, see the sample code here;

What this test-application(and instruction) is about:

Simple helloworld app, which sends you notification every 2 hours. Clicking on notification - opens secondary Activity in the app; deleting notification tracks.

When should you use it:

Once you need to run some task on a scheduled basis. My own case: once a day, I want to fetch new content from server, compose a notification based on the content I got and show it to user.

What to do:

  1. First, let's create 2 activities: MainActivity, which starts notification-service and NotificationActivity, which will be started by clicking notification:


    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android=""
            android:text="Start Sending Notifications Every 2 Hours!" />

    public class MainActivity extends AppCompatActivity {
        protected void onCreate(Bundle savedInstanceState) {
        public void onSendNotificationsButtonClick(View view) {

    and NotificationActivity is any random activity you can come up with. NB! Don't forget to add both activities into AndroidManifest.

  2. Then let's create WakefulBroadcastReceiver broadcast receiver, I called NotificationEventReceiver in code above.

    Here, we'll set up AlarmManager to fire PendingIntent every 2 hours (or with any other frequency), and specify the handled actions for this intent in onReceive() method. In our case - wakefully start IntentService, which we'll specify in the later steps. This IntentService would generate notifications for us.

    Also, this receiver would contain some helper-methods like creating PendintIntents, which we'll use later

    NB1! As I'm using WakefulBroadcastReceiver, I need to add extra-permission into my manifest: <uses-permission android:name="android.permission.WAKE_LOCK" />

    NB2! I use it wakeful version of broadcast receiver, as I want to ensure, that the device does not go back to sleep during my IntentService's operation. In the hello-world it's not that important (we have no long-running operation in our service, but imagine, if you have to fetch some relatively huge files from server during this operation). Read more about Device Awake here.

    public class NotificationEventReceiver extends WakefulBroadcastReceiver {
        private static final int NOTIFICATIONS_INTERVAL_IN_HOURS = 2;
        public static void setupAlarm(Context context) {
            AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
            PendingIntent alarmIntent = getStartPendingIntent(context);
                    getTriggerAt(new Date()),
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            Intent serviceIntent = null;
            if (ACTION_START_NOTIFICATION_SERVICE.equals(action)) {
                Log.i(getClass().getSimpleName(), "onReceive from alarm, starting notification service");
                serviceIntent = NotificationIntentService.createIntentStartNotificationService(context);
            } else if (ACTION_DELETE_NOTIFICATION.equals(action)) {
                Log.i(getClass().getSimpleName(), "onReceive delete notification action, starting notification service to handle delete");
                serviceIntent = NotificationIntentService.createIntentDeleteNotification(context);
            if (serviceIntent != null) {
                startWakefulService(context, serviceIntent);
        private static long getTriggerAt(Date now) {
            Calendar calendar = Calendar.getInstance();
            //calendar.add(Calendar.HOUR, NOTIFICATIONS_INTERVAL_IN_HOURS);
            return calendar.getTimeInMillis();
        private static PendingIntent getStartPendingIntent(Context context) {
            Intent intent = new Intent(context, NotificationEventReceiver.class);
            return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        public static PendingIntent getDeleteIntent(Context context) {
            Intent intent = new Intent(context, NotificationEventReceiver.class);
            return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
  3. Now let's create an IntentService to actually create notifications.

    There, we specify onHandleIntent() which is responses on NotificationEventReceiver's intent we passed in startWakefulService method.

    If it's Delete action - we can log it to our analytics, for example. If it's Start notification intent - then by using NotificationCompat.Builder we're composing new notification and showing it by NotificationManager.notify. While composing notification, we are also setting pending intents for click and remove actions. Fairly Easy.

    public class NotificationIntentService extends IntentService {
        private static final int NOTIFICATION_ID = 1;
        private static final String ACTION_START = "ACTION_START";
        private static final String ACTION_DELETE = "ACTION_DELETE";
        public NotificationIntentService() {
        public static Intent createIntentStartNotificationService(Context context) {
            Intent intent = new Intent(context, NotificationIntentService.class);
            return intent;
        public static Intent createIntentDeleteNotification(Context context) {
            Intent intent = new Intent(context, NotificationIntentService.class);
            return intent;
        protected void onHandleIntent(Intent intent) {
            Log.d(getClass().getSimpleName(), "onHandleIntent, started handling a notification event");
            try {
                String action = intent.getAction();
                if (ACTION_START.equals(action)) {
                if (ACTION_DELETE.equals(action)) {
            } finally {
        private void processDeleteNotification(Intent intent) {
            // Log something?
        private void processStartNotification() {
            // Do something. For example, fetch fresh data from backend to create a rich notification?
            final NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
            builder.setContentTitle("Scheduled Notification")
                    .setContentText("This notification has been triggered by Notification Service")
            PendingIntent pendingIntent = PendingIntent.getActivity(this,
                    new Intent(this, NotificationActivity.class),
            final NotificationManager manager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
  4. Almost done. Now I also add broadcast receiver for BOOT_COMPLETED, TIMEZONE_CHANGED, and TIME_SET events to re-setup my AlarmManager, once device has been rebooted or timezone has changed (For example, user flown from USA to Europe and you don't want notification to pop up in the middle of the night, but was sticky to the local time :-) ).

    public final class NotificationServiceStarterReceiver extends BroadcastReceiver {
        public void onReceive(Context context, Intent intent) {
  5. We need to also register all our services, broadcast receivers in AndroidManifest:

    <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android=""
        <uses-permission android:name="android.permission.INTERNET" />
        <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
        <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
        <uses-permission android:name="android.permission.WAKE_LOCK" />
            <activity android:name=".MainActivity">
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                android:exported="false" />
            <receiver android:name=".broadcast_receivers.NotificationEventReceiver" />
            <receiver android:name=".broadcast_receivers.NotificationServiceStarterReceiver">
                    <action android:name="android.intent.action.BOOT_COMPLETED" />
                    <action android:name="android.intent.action.TIMEZONE_CHANGED" />
                    <action android:name="android.intent.action.TIME_SET" />

That's it!

The source code for this project you can find here. I hope, you will find this post helpful.

How to print multiple variable lines in Java

Or try this one:

System.out.println("First Name: " + firstname + " Last Name: "+ lastname +".");

Good luck!

how to add values to an array of objects dynamically in javascript?

You have to instantiate the object first. The simplest way is:

var lab =["1","2","3"];
var val = [42,55,51,22];
var data = [];
for(var i=0; i<4; i++)  {
    data.push({label: lab[i], value: val[i]});

Or an other, less concise way, but closer to your original code:

for(var i=0; i<4; i++)  {
   data[i] = {};              // creates a new object
   data[i].label = lab[i];
   data[i].value = val[i];    

array() will not create a new array (unless you defined that function). Either Array() or new Array() or just [].

I recommend to read the MDN JavaScript Guide.

Multiple scenarios @RequestMapping produces JSON/XML together with Accept or ResponseEntity

I've preferred using the params filter for parameter-centric content-type.. I believe that should work in conjunction with the produces attribute.

public ResponseEntity<Person> getPerson(@PathVariable Integer id){
    Person person = personMapRepository.findPerson(id);
    return ResponseEntity.ok(person);
public ResponseEntity<Person> getPersonXML(@PathVariable Integer id){
    return GetPerson(id); // delegate

Java stack overflow error - how to increase the stack size in Eclipse?

You need to have a launch configuration inside Eclipse in order to adjust the JVM parameters.

After running your program with either F11 or Ctrl-F11, open the launch configurations in Run -> Run Configurations... and open your program under "Java Applications". Select the Arguments pane, where you will find "VM arguments".

This is where -Xss1024k goes.

If you want the launch configuration to be a file in your workspace (so you can right click and run it), select the Common pane, and check the Save as -> Shared File checkbox and browse to the location you want the launch file. I usually have them in a separate folder, as we check them into CVS.

How do I use itertools.groupby()?

Sorting and groupby

from itertools import groupby

val = [{'name': 'satyajit', 'address': 'btm', 'pin': 560076}, 
       {'name': 'Mukul', 'address': 'Silk board', 'pin': 560078},
       {'name': 'Preetam', 'address': 'btm', 'pin': 560076}]

for pin, list_data in groupby(sorted(val, key=lambda k: k['pin']),lambda x: x['pin']):
...     print pin
...     for rec in list_data:
...             print rec

{'name': 'satyajit', 'pin': 560076, 'address': 'btm'}
{'name': 'Preetam', 'pin': 560076, 'address': 'btm'}
{'name': 'Mukul', 'pin': 560078, 'address': 'Silk board'}

How to solve static declaration follows non-static declaration in GCC C code?

I have had this issue in a case where the static function was called before it was declared. Moving the function declaration to anywhere above the call solved my problem.

Change output format for MySQL command line results to CSV

If you are using mysql client you can set up the resultFormat per session e.g.

mysql -h localhost -u root --resutl-format=json


mysql -h localhost -u root --vertical

Check out the full list of arguments here.

django MultiValueDictKeyError error, how do I deal with it

First check if the request object have the 'is_private' key parameter. Most of the case's this MultiValueDictKeyError occurred for missing key in the dictionary-like request object. Because dictionary is an unordered key, value pair “associative memories” or “associative arrays”

In another word. request.GET or request.POST is a dictionary-like object containing all request parameters. This is specific to Django.

The method get() returns a value for the given key if key is in the dictionary. If key is not available then returns default value None.

You can handle this error by putting :

is_private = request.POST.get('is_private', False);

Decompile an APK, modify it and then recompile it

I know this question has been answered and I am not trying to give better answer here. I'll just share my experience in this topic.

Once I lost my code and I had the apk file only. I decompiled it using the tool below and it made my day.

These tools MUST be used in such situation, otherwise, it is unethical and even sometimes it is illegal, (stealing somebody else's effort). So please use it wisely.

Those are my favorite tools for doing that:

and to get the apk from google play you can google it or check out those sites:

On the date of posting this answer I tested all the links and it worked perfect for me.

NOTE: Apk Decompiling is not effective in case of proguarded code. Because Proguard shrink and obfuscates the code and rename classes to nonsense names which make it fairly hard to understand the code.


Basic tutorial of Using Proguard:

Google MAP API v3: Center & Zoom on displayed markers

Try this works...

$(function() {
        var myOptions = {
            zoom: 10,
            center: latlng,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        var map = new google.maps.Map(document.getElementById("map_canvas"),myOptions);
        var latlng_pos=[];
        var j=0;
            latlng_pos[j]=new google.maps.LatLng($(this).find(".latitude").val(),$(this).find(".longitude").val());
            var marker = new google.maps.Marker({
                position: new google.maps.LatLng($(this).find(".latitude").val(),$(this).find(".longitude").val()),
                // position: new google.maps.LatLng(-35.397, 150.640),
                map: map
        // map: an instance of google.maps.Map object
        // latlng: an array of google.maps.LatLng objects
        var latlngbounds = new google.maps.LatLngBounds( );
        for ( var i = 0; i < latlng_pos.length; i++ ) {
            latlngbounds.extend( latlng_pos[ i ] );
        map.fitBounds( latlngbounds );


Select tableview row programmatically

Use this category to select a table row and execute a given segue after a delay.
Call this within your viewDidAppear method:

[tableViewController delayedSelection:withSegueIdentifier:]

@implementation UITableViewController (TLUtils)

-(void)delayedSelection:(NSIndexPath *)idxPath withSegueIdentifier:(NSString *)segueID {
    if (!idxPath) idxPath = [NSIndexPath indexPathForRow:0 inSection:0];                                                                                                                                                                 
    [self performSelector:@selector(selectIndexPath:) withObject:@{@"NSIndexPath": idxPath, @"UIStoryboardSegue": segueID } afterDelay:0];                                                                                               

-(void)selectIndexPath:(NSDictionary *)args {
    NSIndexPath *idxPath = args[@"NSIndexPath"];                                                                                                                                                                                         
    [self.tableView selectRowAtIndexPath:idxPath animated:NO scrollPosition:UITableViewScrollPositionMiddle];                                                                                                                            

    if ([self.tableView.delegate respondsToSelector:@selector(tableView:didSelectRowAtIndexPath:)])
        [self.tableView.delegate tableView:self.tableView didSelectRowAtIndexPath:idxPath];                                                                                                                                              

    [self performSegueWithIdentifier:args[@"UIStoryboardSegue"] sender:self];                                                                                                                                                            


How do I translate an ISO 8601 datetime string into a Python datetime object?

Both ways:

Epoch to ISO time:

isoTime = time.strftime('%Y-%m-%dT%H:%M:%SZ', time.gmtime(epochTime))

ISO time to Epoch:

epochTime = time.mktime(time.strptime(isoTime, '%Y-%m-%dT%H:%M:%SZ'))

JQuery: detect change in input field

Use $.on() to bind your chosen event to the input, don't use the shortcuts like $.keydown() etc because as of jQuery 1.7 $.on() is the preferred method to attach event handlers (see here: and

$.keydown() is just a shortcut to $.bind('keydown'), and $.bind() is what $.on() replaces (among others).

To answer your question, as far as I'm aware, unless you need to fire an event on keydown specifically, the change event should do the trick for you.

$('element').on('change', function(){

To respond to the below comment, the javascript change event is documented here:

And here is a working example of the change event working on an input element, using jQuery:

Java foreach loop: for (Integer i : list) { ... }

Another way, you can use a pass-through object to capture the last value and then do something with it:

List<Integer> list = new ArrayList<Integer>();
Integer lastValue = null;
for (Integer i : list) {
    // do stuff
    lastValue = i;
// do stuff with last value

Android emulator not able to access the internet

go to your adapter setting and change the dns to which is google's and it will work,it worked for me

How do I write a compareTo method which compares objects?

if (s.compareTo(t) > 0) will compare string s to string t and return the int value you want.

    public int Compare(Object obj) // creating a method to compare {   
        Student s = (Student) obj; //creating a student object

        // compare last names
        return  this.lastName.compareTo(s.getLastName());    

Now just test for a positive negative return from the method as you would have normally.


'cl' is not recognized as an internal or external command,

I think cl isn't in your path. You need to add it there. The recommended way to do this is to launch a developer command prompt.

Quoting the article Setting the Path and Environment Variables for Command-Line Builds:

To open a Developer Command Prompt window

  1. With the Windows 8 Start screen showing, type Visual Studio Tools. Notice that the search results change as you type; when Visual Studio Tools appears, choose it.

    On earlier versions of Windows, choose Start, and then in the search box, type Visual Studio Tools. When Visual Studio Tools appears in the search results, choose it.

  2. In the Visual Studio Tools folder, open the Developer Command Prompt for your version of Visual Studio. (To run as administrator, open the shortcut menu for the Developer Command Prompt and choose Run as Administrator.)

As the article notes, there are several different shortcuts for setting up different toolsets - you need to pick the suitable one.

If you already have a plain Command Prompt window open, you can run the batch file vcvarsall.bat with the appropriate argument to set up the environment variables. Quoting the same article:

To run vcvarsall.bat

  1. At the command prompt, change to the Visual C++ installation directory. (The location depends on the system and the Visual Studio installation, but a typical location is C:\Program Files (x86)\Microsoft Visual Studio version\VC.) For example, enter:

    cd "\Program Files (x86)\Microsoft Visual Studio 12.0\VC"
  2. To configure this Command Prompt window for 32-bit x86 command-line builds, at the command prompt, enter:

    vcvarsall x86

From the article, the possible arguments are the following:

  • x86 (x86 32-bit native)
  • x86_amd64 (x64 on x86 cross)
  • x86_arm (ARM on x86 cross)
  • amd64 (x64 64-bit native)
  • amd64_x86 (x86 on x64 cross)
  • amd64_arm (ARM on x64 cross)

Setting up Gradle for api 26 (Android)

allprojects {
    repositories {
        maven {
            url ""

android {
    compileSdkVersion 26
    buildToolsVersion "26.0.1"
    defaultConfig {
        applicationId "com.keshav.retroft2arrayinsidearrayexamplekeshav"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner ""
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), ''
 compile ''
    compile ''
    compile ''

How can I add a class attribute to an HTML element generated by MVC's HTML Helpers?

Current best practice in CSS development is to create more general selectors with modifiers that can be applied as widely as possible throughout the web site. I would try to avoid defining separate styles for individual page elements.

If the purpose of the CSS class on the <form/> element is to control the style of elements within the form, you could add the class attribute the existing <fieldset/> element which encapsulates any form by default in web pages generated by ASP.NET MVC. A CSS class on the form is rarely necessary.

What does 'corrupted double-linked list' mean

This might be caused due to different reasons, some user have mentioned other possibilities and I add my case:

I got this error when using multi-threading (both std::pthread and std::thread) and the error occurred because I forgot to lock a variable which multi threads may change at the same time. this error comes randomly in some runs but not all because ... you know accident between to threads is random.

That variable in my case was a global std::vector which I tried to push_back() something into it in a function called by threads.. and then I used a std::mutex and never got this error again.

may help some

What is the difference between CHARACTER VARYING and VARCHAR in PostgreSQL?

The PostgreSQL documentation on Character Types is a good reference for this. They are two different names for the same type.

Split long commands in multiple lines through Windows batch file

(This is basically a rewrite of Wayne's answer but with the confusion around the caret cleared up. So I've posted it as a CW. I'm not shy about editing answers, but completely rewriting them seems inappropriate.)

You can break up long lines with the caret (^), just remember that the caret and the newline that follows it are removed entirely from the command, so if you put it where a space would be required (such as between parameters), be sure to include the space as well (either before the ^, or at the beginning of the next line — that latter choice may help make it clearer it's a continuation).

Examples: (all tested on Windows XP and Windows 7)

xcopy file1.txt file2.txt

can be written as:



xcopy ^
file1.txt ^

or even

opy ^
file1.txt ^

(That last works because there are no spaces betwen the xc and the ^, and no spaces at the beginning of the next line. So when you remove the ^ and the newline, you get...xcopy.)

For readability and sanity, it's probably best breaking only between parameters (be sure to include the space).

Be sure that the ^ is not the last thing in a batch file, as there appears to be a major issue with that.

Reading int values from SqlDataReader

you can use


to read an 32 bit int from the data reader.

If you know the type of your data I think its better to read using the Get* methods which are strongly typed rather than just reading an object and casting.

Have you considered using


rather than accessing by position. This makes your code less brittle and will not break if you change the query to add new columns before the existing ones. If you are going to do this in a loop, cache the ordinal first.

Python RuntimeWarning: overflow encountered in long scalars

An easy way to overcome this problem is to use 64 bit type

list = numpy.array(list, dtype=numpy.float64)