Programs & Examples On #Staging

Staging is the process of deploying to an intermediate, usually internal, repository so that deployed artifacts can be tested and later promoted to higher levels so that they can finally be release to public repositories

git add only modified changes and ignore untracked files

git commit -a -m "message"

-a : Includes all currently changed/deleted files in this commit. Keep in mind, however, that untracked (new) files are not included.

-m : Sets the commit's message

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

For newer versions of Git there is git restore --staged <file>.

When I do a git status with Git version it is also recommended for unstaging:

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)

(This post shows, that in earlier versions git reset HEAD was recommended at this point)

I can highly recommend this post explaining the differences between git revert, git restore and git reset and also additional parameters for git restore.

How to use JavaScript regex over multiple lines?


This one was beyond helpful for me, especially for matching multiple things that include new lines, every single other answer ended up just grouping all of the matches together.

Explain why constructor inject is better than other options

Constructor injection is used when the class cannot function without the dependent class.

Property injection is used when the class can function without the dependent class.

As a concrete example, consider a ServiceRepository which depends on IService to do its work. Since ServiceRepository cannot function usefully without IService, it makes sense to have it injected via the constructor.

The same ServiceRepository class may use a Logger to do tracing. The ILogger can be injected via Property injection.

Other common examples of Property injection are ICache (another aspect in AOP terminology) or IBaseProperty (a property in the base class).

How to prevent form from submitting multiple times from client side?

Use unobtrusive javascript to disable the submit event on the form after it has already been submitted. Here is an example using jQuery.

EDIT: Fixed issue with submitting a form without clicking the submit button. Thanks, ichiban.

$("body").on("submit", "form", function() {
    $(this).submit(function() {
        return false;
    return true;

Oracle SQL: Use sequence in insert with Select Statement

I tested and the script run ok!

    WHERE YEAR = '2010' AND MONTH = '12'

you can read this article to understand more!

Writing binary number system in C code

Standard C doesn't define binary constants. There's a GNU (I believe) extension though (among popular compilers, clang adapts it as well): the 0b prefix:

int foo = 0b1010;

If you want to stick with standard C, then there's an option: you can combine a macro and a function to create an almost readable "binary constant" feature:

#define B(x) S_to_binary_(#x)

static inline unsigned long long S_to_binary_(const char *s)
        unsigned long long i = 0;
        while (*s) {
                i <<= 1;
                i += *s++ - '0';
        return i;

And then you can use it like this:

int foo = B(1010);

If you turn on heavy compiler optimizations, the compiler will most likely eliminate the function call completely (constant folding) or will at least inline it, so this won't even be a performance issue.


The following code:

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>

#define B(x) S_to_binary_(#x)

static inline unsigned long long S_to_binary_(const char *s)
    unsigned long long i = 0;
    while (*s) {
        i <<= 1;
        i += *s++ - '0';
    return i;

int main()
    int foo = B(001100101);

    printf("%d\n", foo);

    return 0;

has been compiled using clang -o baz.S baz.c -Wall -O3 -S, and it produced the following assembly:

    .section    __TEXT,__text,regular,pure_instructions
    .globl  _main
    .align  4, 0x90
_main:                                  ## @main
## BB#0:
    pushq   %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register %rbp
    leaq    L_.str1(%rip), %rdi
    movl    $101, %esi               ## <= This line!
    xorb    %al, %al
    callq   _printf
    xorl    %eax, %eax
    popq    %rbp

    .section    __TEXT,__cstring,cstring_literals
L_.str1:                                ## @.str1
    .asciz   "%d\n"


So clang completely eliminated the call to the function, and replaced its return value with 101. Neat, huh?

Preloading CSS Images

The only way is to Base64 encode the image and place it inside the HTML code so that it doesn't need to contact the server to download the image.

This will encode an image from url so you can copy the image file code and insert it in your page like so...

body {

Select All distinct values in a column using LINQ

Interestingly enough I tried both of these in LinqPad and the variant using group from Dmitry Gribkov by appears to be quicker. (also the final distinct is not required as the result is already distinct.

My (somewhat simple) code was:

public class Pair 
    public int id {get;set;}
    public string Arb {get;set;}

void Main()

    var theList = new List<Pair>();
    var randomiser = new Random();
    for (int count = 1; count < 10000; count++)
        theList.Add(new Pair 
            id = randomiser.Next(1, 50),
            Arb = "not used"

    var timer = new Stopwatch();
    var distinct = theList.GroupBy(c => => p.First().id);

    var otherDistinct = theList.Select(p =>;

String, StringBuffer, and StringBuilder

Note that if you are using Java 5 or newer, you should use StringBuilder instead of StringBuffer. From the API documentation:

As of release JDK 5, this class has been supplemented with an equivalent class designed for use by a single thread, StringBuilder. The StringBuilder class should generally be used in preference to this one, as it supports all of the same operations but it is faster, as it performs no synchronization.

In practice, you will almost never use this from multiple threads at the same time, so the synchronization that StringBuffer does is almost always unnecessary overhead.

How do I return a proper success/error message for JQuery .ajax() using PHP?

Server side:

if (mysql_query($query)) {
    // ...
else {

Client side:

error: function() {
    alert("There was an error. Try again please!");
success: function(){
    alert("Thank you for subscribing!");

How to configure "Shorten command line" method for whole project in IntelliJ

Inside your .idea folder, change workspace.xml file


<property name="dynamic.classpath" value="true" />


  <component name="PropertiesComponent">


 <component name="PropertiesComponent">
    <property name="project.structure.last.edited" value="Project" />
    <property name="project.structure.proportion" value="0.0" />
    <property name="project.structure.side.proportion" value="0.0" />
    <property name="settings.editor.selected.configurable" value="preferences.pluginManager" />
    <property name="dynamic.classpath" value="true" />

If you don't see one, feel free to add it yourself

 <component name="PropertiesComponent">
    <property name="dynamic.classpath" value="true" />

Simple C example of doing an HTTP POST and consuming the response

Handle added.
Added Host header.
Added linux / windows support, tested (XP,WIN7).
WARNING: ERROR : "segmentation fault" if no host,path or port as argument.

#include <stdio.h> /* printf, sprintf */
#include <stdlib.h> /* exit, atoi, malloc, free */
#include <unistd.h> /* read, write, close */
#include <string.h> /* memcpy, memset */
#ifdef __linux__ 
    #include <sys/socket.h> /* socket, connect */
    #include <netdb.h> /* struct hostent, gethostbyname */
    #include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
#elif _WIN32
    #include <winsock2.h>
    #include <ws2tcpip.h>
    #include <windows.h>
    #pragma comment(lib,"ws2_32.lib") //Winsock Library



void error(const char *msg) { perror(msg); exit(0); }

int main(int argc,char *argv[])

    int i;
    struct hostent *server;
    struct sockaddr_in serv_addr;
    int bytes, sent, received, total, message_size;
    char *message, response[4096];
    int portno = atoi(argv[2])>0?atoi(argv[2]):80;
    char *host = strlen(argv[1])>0?argv[1]:"localhost";
    char *path = strlen(argv[4])>0?argv[4]:"/";
    if (argc < 5) { puts("Parameters: <host> <port> <method> <path> [<data> [<headers>]]"); exit(0); }
    /* How big is the message? */
                printf("Process 1\n");
        message_size+=strlen("%s %s%s%s HTTP/1.0\r\nHost: %s\r\n");        /* method         */
        message_size+=strlen(argv[3]);                         /* path           */
        message_size+=strlen(path);                         /* headers        */
            message_size+=strlen(argv[5]);                     /* query string   */
        for(i=6;i<argc;i++)                                    /* headers        */
        message_size+=strlen("\r\n");                          /* blank line     */
                printf("Process 2\n");
        message_size+=strlen("%s %s HTTP/1.0\r\nHost: %s\r\n");
        message_size+=strlen(argv[3]);                         /* method         */
        message_size+=strlen(path);                            /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            message_size+=strlen("Content-Length: %d\r\n")+10; /* content length */
        message_size+=strlen("\r\n");                          /* blank line     */
            message_size+=strlen(argv[5]);                     /* body           */
    /* allocate space for the message */

    /* fill in the parameters */
            sprintf(message,"%s %s%s%s HTTP/1.0\r\nHost: %s\r\n",
                strlen(argv[3])>0?argv[3]:"GET",               /* method         */
                path,                                          /* path           */
                strlen(argv[5])>0?"?":"",                      /* ?              */
                strlen(argv[5])>0?argv[5]:"",host);            /* query string   */
            sprintf(message,"%s %s HTTP/1.0\r\nHost: %s\r\n",
                strlen(argv[3])>0?argv[3]:"GET",               /* method         */
                path,host);                                    /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
        strcat(message,"\r\n");                                /* blank line     */
        sprintf(message,"%s %s HTTP/1.0\r\nHost: %s\r\n",
            strlen(argv[3])>0?argv[3]:"POST",                  /* method         */
            path,host);                                        /* path           */
        for(i=6;i<argc;i++)                                    /* headers        */
            sprintf(message+strlen(message),"Content-Length: %d\r\n",(int)strlen(argv[5]));
        strcat(message,"\r\n");                                /* blank line     */
            strcat(message,argv[5]);                           /* body           */
    /* What are we going to send? */
        /* lookup the ip address */

    total = strlen(message);
    /* create the socket */
    #ifdef _WIN32

printf("\nInitialising Winsock...");
if (WSAStartup(MAKEWORD(2,2),&wsa) != 0)
    printf("Failed. Error Code : %d",WSAGetLastError());
    return 1;


//Create a socket
if((s = socket(AF_INET , SOCK_STREAM , 0 )) == INVALID_SOCKET)
    printf("Could not create socket : %d" , WSAGetLastError());

printf("Socket created.\n");

server = gethostbyname(host);
serv_addr.sin_addr.s_addr = inet_addr(server->h_addr);
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(portno);
//Connect to remote server
if (connect(s , (struct sockaddr *)&serv_addr , sizeof(serv_addr)) < 0)
    printf("connect failed with error code : %d" , WSAGetLastError());
    return 1;

if( send(s , message , strlen(message) , 0) < 0)
    printf("Send failed with error code : %d" , WSAGetLastError());
    return 1;
puts("Data Send\n");

//Receive a reply from the server
if((received = recv(s , response , 2000 , 0)) == SOCKET_ERROR)
    printf("recv failed with error code : %d" , WSAGetLastError());

puts("Reply received\n");

//Add a NULL terminating character to make it a proper string before printing
response[received] = '\0';

    #ifdef __linux__ 
    int sockfd;
    server = gethostbyname(host);
    if (server == NULL) error("ERROR, no such host");
        sockfd = socket(AF_INET, SOCK_STREAM, 0);
        if (sockfd < 0) error("ERROR opening socket");
        /* fill in the structure */
        serv_addr.sin_family = AF_INET;
        serv_addr.sin_port = htons(portno);
                /* connect the socket */
        if (connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(serv_addr)) < 0)
            error("ERROR connecting");
                /* send the request */

    sent = 0;
    do {
        bytes = write(sockfd,message+sent,total-sent);
        if (bytes < 0)
            error("ERROR writing message to socket");
        if (bytes == 0)
    } while (sent < total);
    /* receive the response */
    memset(response, 0, sizeof(response));
    total = sizeof(response)-1;
    received = 0;
    printf("Response: \n");
    do {
       printf("%s", response);
       memset(response, 0, sizeof(response));
       bytes = recv(sockfd, response, 1024, 0);
        if (bytes < 0)
           printf("ERROR reading response from socket");
       if (bytes == 0)
    } while (1);

    if (received == total)
        error("ERROR storing complete response from socket");

    /* close the socket */


    return 0;

create table in postgreSQL

First the bigint(20) not null auto_increment will not work, simply use bigserial primary key. Then datetime is timestamp in PostgreSQL. All in all:

CREATE TABLE article (
    article_id bigserial primary key,
    article_name varchar(20) NOT NULL,
    article_desc text NOT NULL,
    date_added timestamp default NULL

Eloquent get only one column as an array

I came across this question and thought I would clarify that the lists() method of a eloquent builder object was depreciated in Laravel 5.2 and replaced with pluck().

// <= Laravel 5.1
Word_relation::where('word_one', $word_id)->lists('word_one')->toArray();
// >= Laravel 5.2
Word_relation::where('word_one', $word_id)->pluck('word_one')->toArray();

These methods can also be called on a Collection for example

// <= Laravel 5.1
  $collection = Word_relation::where('word_one', $word_id)->get();
  $array = $collection->lists('word_one');

// >= Laravel 5.2
  $collection = Word_relation::where('word_one', $word_id)->get();
  $array = $collection->pluck('word_one');

Display special characters when using print statement

Use repr:

a = "Hello\tWorld\nHello World"
# 'Hello\tWorld\nHello World'

Note you do not get \s for a space. I hope that was a typo...?

But if you really do want \s for spaces, you could do this:

print(repr(a).replace(' ',r'\s'))

How can I introduce multiple conditions in LIKE operator?

Oracle 10g has functions that allow the use of POSIX-compliant regular expressions in SQL:


See the Oracle Database SQL Reference for syntax details on this functions.

Take a look at Regular expressions in Perl with examples.

Code :

    select * from tbl where regexp_like(col, '^(ABC|XYZ|PQR)');

Removing duplicate rows from table in Oracle

From Ask Tom

delete from t
 where rowid IN ( select rid
                    from (select rowid rid, 
                                 row_number() over (partition by 
                         companyid, agentid, class , status, terminationdate
                                   order by rowid) rn
                            from t)
                   where rn <> 1);

(fixed the missing parenthesis)

Format a JavaScript string using placeholders and an object of substitutions?

How about using ES6 template literals?

var a = "cat";
var b = "fat";
console.log(`my ${a} is ${b}`); //notice back-ticked string

More about template literals...

What is the difference between an expression and a statement in Python?

Though this isn't related to Python:

An expression evaluates to a value. A statement does something.

>>> x + 2         # an expression
>>> x = 1         # a statement 
>>> y = x + 1     # a statement
>>> print y       # a statement (in 2.x)

Using the "animated circle" in an ImageView while loading stuff

You can do this by using the following xml


With this style

<style name="GenericProgressBackground" parent="android:Theme">
    <item name="android:layout_width">fill_parent</item>    
    <item name="android:layout_height">fill_parent</item>
    <item name="android:background">#DD111111</item>    
    <item name="android:gravity">center</item>  
<style name="GenericProgressIndicator" parent="@android:style/Widget.ProgressBar.Small">
    <item name="android:layout_width">wrap_content</item>
    <item name="android:layout_height">wrap_content</item>
    <item name="android:indeterminate">true</item> 

To use this, you must hide your UI elements by setting the visibility value to GONE and whenever the data is loaded, call setVisibility(View.VISIBLE) on all your views to restore them. Don't forget to call findViewById( to hide the loading animation.

If you dont have a loading event/function but just want the loading panel to disappear after x seconds use a Handle to trigger the hiding/showing.

Plot different DataFrames in the same figure

Although Chang's answer explains how to plot multiple times on the same figure, in this case you might be better off in this case using a groupby and unstacking:

(Assuming you have this in dataframe, with datetime index already)

In [1]: df
2010-01-01      1  
2010-02-01      1  
2009-01-01      1  

# create additional month and year columns for convenience
df['Month'] = map(lambda x: x.month, df.index)
df['Year'] = map(lambda x: x.year, df.index)    

In [5]: df.groupby(['Month','Year']).mean().unstack()
Year    2009  2010
1          1     1
2        NaN     1

Now it's easy to plot (each year as a separate line):


Why do we use Base64?

It is more that the media validates the string encoding, so we want to ensure that the data is acceptable by a handling application (and doesn't contain a binary sequence representing EOL for example)

Imagine you want to send binary data in an email with encoding UTF-8 -- The email may not display correctly if the stream of ones and zeros creates a sequence which isn't valid Unicode in UTF-8 encoding.

The same type of thing happens in URLs when we want to encode characters not valid for a URL in the URL itself: my friend ->

This is because we want to send a space over a system that will think the space is smelly.

All we are doing is ensuring there is a 1-to-1 mapping between a known good, acceptable and non-detrimental sequence of bits to another literal sequence of bits, and that the handling application doesn't distinguish the encoding.

In your example, man may be valid ASCII in first form; but often you may want to transmit values that are random binary (ie sending an image in an email):

MIME-Version: 1.0
Content-Description: "Base64 encode of a.gif"
Content-Type: image/gif; name="a.gif"
Content-Transfer-Encoding: Base64
Content-Disposition: attachment; filename="a.gif"

Here we see that a GIF image is encoded in base64 as a chunk of an email. The email client reads the headers and decodes it. Because of the encoding, we can be sure the GIF doesn't contain anything that may be interpreted as protocol and we avoid inserting data that SMTP or POP may find significant.

How to get a reference to an iframe's window object inside iframe's onload handler created from parent window

You're declaring everything in the parent page. So the references to window and document are to the parent page's. If you want to do stuff to the iframe's, use iframe || iframe.contentWindow to access its window, and iframe.contentDocument || iframe.contentWindow.document to access its document.

There's a word for what's happening, possibly "lexical scope": What is lexical scope?

The only context of a scope is this. And in your example, the owner of the method is doc, which is the iframe's document. Other than that, anything that's accessed in this function that uses known objects are the parent's (if not declared in the function). It would be a different story if the function were declared in a different place, but it's declared in the parent page.

This is how I would write it:

(function () {
  var dom, win, doc, where, iframe;

  iframe = document.createElement('iframe');
  iframe.src = "javascript:false";

  where = document.getElementsByTagName('script')[0];
  where.parentNode.insertBefore(iframe, where);

  win = iframe.contentWindow || iframe;
  doc = iframe.contentDocument || iframe.contentWindow.document;;
  doc._l = (function (w, d) {
    return function () {
      w.vanishing_global = new Date().getTime();

      var js = d.createElement("script");
      js.src = 'test-vanishing-global.js?' + w.vanishing_global; = "foobar";
      d.foobar = "foobar:" + Math.random();
      d.foobar = "barfoo:" + Math.random();
  })(win, doc);
  doc.write('<body onload="document._l();"></body>');

The aliasing of win and doc as w and d aren't necessary, it just might make it less confusing because of the misunderstanding of scopes. This way, they are parameters and you have to reference them to access the iframe's stuff. If you want to access the parent's, you still use window and document.

I'm not sure what the implications are of adding methods to a document (doc in this case), but it might make more sense to set the _l method on win. That way, things can be run without a prefix...such as <body onload="_l();"></body>

SQL SELECT from multiple tables

SELECT, p.cid, p.pname, c1.name1, c2.name2
FROM product AS p
    LEFT JOIN customer1 AS c1
        ON p.cid = c1.cid
    LEFT JOIN customer2 AS c2
        ON p.cid = c2.cid

Entity Framework Migrations renaming tables and columns

If you don't like writing/changing the required code in the Migration class manually, you can follow a two-step approach which automatically make the RenameColumn code which is required:

Step One Use the ColumnAttribute to introduce the new column name and then add-migration (e.g. Add-Migration ColumnChanged)

public class ReportPages
    [Column("Section_Id")]                 //Section_Id
    public int Group_Id{get;set}

Step-Two change the property name and again apply to same migration (e.g. Add-Migration ColumnChanged -force) in the Package Manager Console

public class ReportPages
    [Column("Section_Id")]                 //Section_Id
    public int Section_Id{get;set}

If you look at the Migration class you can see the automatically code generated is RenameColumn.

Which characters need to be escaped in HTML?

The exact answer depends on the context. In general, these characters must not be present (HTML 5.2 §

Text nodes and attribute values must consist of Unicode characters, must not contain U+0000 characters, must not contain permanently undefined Unicode characters (noncharacters), and must not contain control characters other than space characters. This specification includes extra constraints on the exact value of Text nodes and attribute values depending on their precise context.

For elements in HTML, the constraints of the Text content model also depends on the kind of element. For instance, an "<" inside a textarea element does not need to be escaped in HTML because textarea is an escapable raw text element.

These restrictions are scattered across the specification. E.g., attribute values (§ must not contain an ambiguous ampersand and be either (i) empty, (ii) within single quotes (and thus must not contain U+0027 APOSTROPHE character '), (iii) within double quotes (must not contain U+0022 QUOTATION MARK character "), or (iv) unquoted — with the following restrictions:

... must not contain any literal space characters, any U+0022 QUOTATION MARK characters ("), U+0027 APOSTROPHE characters ('), U+003D EQUALS SIGN characters (=), U+003C LESS-THAN SIGN characters (<), U+003E GREATER-THAN SIGN characters (>), or U+0060 GRAVE ACCENT characters (`), and must not be the empty string.

How do I convert a datetime to date?

You use the method:

Obviously, the expression above can (and should IMHO :) be written as:

correct way to define class variables in Python

I think this sample explains the difference between the styles:

#!/usr/bin/env python

class MyClass:
    element1 = "Hello"

    def __init__(self):
        self.element2 = "World"

obj = MyClass()

print dir(MyClass)
print "--"
print dir(obj)
print "--"
print obj.element1 
print obj.element2
print MyClass.element1 + " " + MyClass.element2
['__doc__', '__init__', '__module__', 'element1']
['__doc__', '__init__', '__module__', 'element1', 'element2']
Hello World
Traceback (most recent call last):
  File "./", line 17, in <module>
    print MyClass.element2
AttributeError: class MyClass has no attribute 'element2'

element1 is bound to the class, element2 is bound to an instance of the class.

How to normalize a vector in MATLAB efficiently? Any related built-in function?

Fastest by far (time is in comparison to Jacobs):

clc; clear all;
V = rand(1024*1024*32,1);
N = 10;
for i=1:N, 
    d = 1/sqrt(V(1)*V(1)+V(2)*V(2)+V(3)*V(3)); 
    V1 = V*d;
toc % 1.5s

Fixing broken UTF-8 encoding

In my case, I found out by using "mb_convert_encoding" that the previous encoding was iso-8859-1 (which is latin1) then I fixed my problem by using an sql query :

UPDATE myDB.myTable SET myColumn = CAST(CAST(CONVERT(myColumn USING latin1) AS binary) AS CHAR)

However, it is stated in the mysql documentations that conversion may be lossy if the column contains characters that are not in both character sets.

How do you calculate log base 2 in Java for integers?

let's add:

int[] fastLogs;

private void populateFastLogs(int length) {
    fastLogs = new int[length + 1];
    int counter = 0;
    int log = 0;
    int num = 1;
    fastLogs[0] = 0;
    for (int i = 1; i < fastLogs.length; i++) {
        fastLogs[i] = log;
        if (counter == num) {
            num *= 2;
            counter = 0;


How to manually install an artifact in Maven 2?

You need to indicate the groupId, the artifactId and the version for your artifact:

mvn install:install-file \
  -DgroupId=javax.transaction \
  -DartifactId=jta \
  -Dpackaging=jar \
  -Dversion=1.0.1B \
  -Dfile=jta-1.0.1B.jar \

No suitable driver found for 'jdbc:mysql://localhost:3306/mysql

In this particular case (assuming that the Class#forName() didn't throw an exception; your code is namely continuing with running instead of throwing the exception), this SQLException means that Driver#acceptsURL() has returned false for any of the loaded drivers.

And indeed, your JDBC URL is wrong:

String url = "'jdbc:mysql://localhost:3306/mysql";

Remove the singlequote:

String url = "jdbc:mysql://localhost:3306/mysql";

See also:

Determine Whether Integer Is Between Two Other Integers?

Define the range between the numbers:

r = range(1,10)

Then use it:

if num in r:
    print("All right!")

Bulk create model objects in django

Use bulk_create() method. It's standard in Django now.


    Entry(headline="Django 1.0 Released"),
    Entry(headline="Django 1.1 Announced"),
    Entry(headline="Breaking: Django is awesome")

Getting Exception(org.apache.poi.openxml4j.exception - no content type [M1.13]) when reading xlsx file using Apache POI?

I get the same exception for .xls file, but after I open the file and save it as xlsx file , the below code works:

 try(InputStream is =file.getInputStream()){
      XSSFWorkbook workbook = new XSSFWorkbook(is);

How do I get column names to print in this C# program?

Code for Find the Column Name same as using the Like in sql.

foreach (DataGridViewColumn column in GrdMarkBook.Columns)  
                      //GrdMarkBook is Data Grid name
    string HeaderName = column.HeaderText.ToString();

    //  This line Used for find any Column Have Name With Exam

    if (column.HeaderText.ToString().ToUpper().Contains("EXAM"))
        int CoumnNo = column.Index;

Not able to change TextField Border Color

That is not changing due to the default theme set to the screen.

So just change them for the widget you are drawing by wrapping your TextField with new ThemeData()

child: new Theme(
          data: new ThemeData(
            primaryColor: Colors.redAccent,
          child: new TextField(
            decoration: new InputDecoration(
                border: new OutlineInputBorder(
                    borderSide: new BorderSide(color: Colors.teal)),
                hintText: 'Tell us about yourself',
                helperText: 'Keep it short, this is just a demo.',
                labelText: 'Life story',
                prefixIcon: const Icon(
                prefixText: ' ',
                suffixText: 'USD',
                suffixStyle: const TextStyle(color:,

enter image description here

fatal: Not a valid object name: 'master'

Git creates a master branch once you've done your first commit. There's nothing to have a branch for if there's no code in the repository.

Check if table exists in SQL Server

IF OBJECT_ID('mytablename') IS NOT NULL 

How to make parent wait for all child processes to finish?

POSIX defines a function: wait(NULL);. It's the shorthand for waitpid(-1, NULL, 0);, which will suspends the execution of the calling process until any one child process exits. Here, 1st argument of waitpid indicates wait for any child process to end.

In your case, have the parent call it from within your else branch.

How to define an enum with string value?

We can't define enumeration as string type. The approved types for an enum are byte, sbyte, short, ushort, int, uint, long, or ulong.

If you need more details on enumeration please follow below link,that link will help you to understand enumeration. Enumeration


Convert json data to a html table

I have rewritten your code in vanilla-js, using DOM methods to prevent html injection.


var _table_ = document.createElement('table'),_x000D_
  _tr_ = document.createElement('tr'),_x000D_
  _th_ = document.createElement('th'),_x000D_
  _td_ = document.createElement('td');_x000D_
// Builds the HTML Table out of myList json data from Ivy restful service._x000D_
function buildHtmlTable(arr) {_x000D_
  var table = _table_.cloneNode(false),_x000D_
    columns = addAllColumnHeaders(arr, table);_x000D_
  for (var i = 0, maxi = arr.length; i < maxi; ++i) {_x000D_
    var tr = _tr_.cloneNode(false);_x000D_
    for (var j = 0, maxj = columns.length; j < maxj; ++j) {_x000D_
      var td = _td_.cloneNode(false);_x000D_
      cellValue = arr[i][columns[j]];_x000D_
      td.appendChild(document.createTextNode(arr[i][columns[j]] || ''));_x000D_
  return table;_x000D_
// Adds a header row to the table and returns the set of columns._x000D_
// Need to do union of keys from all records as some records may not contain_x000D_
// all records_x000D_
function addAllColumnHeaders(arr, table) {_x000D_
  var columnSet = [],_x000D_
    tr = _tr_.cloneNode(false);_x000D_
  for (var i = 0, l = arr.length; i < l; i++) {_x000D_
    for (var key in arr[i]) {_x000D_
      if (arr[i].hasOwnProperty(key) && columnSet.indexOf(key) === -1) {_x000D_
        var th = _th_.cloneNode(false);_x000D_
  return columnSet;_x000D_
    "name": "abc",_x000D_
    "age": 50_x000D_
    "age": "25",_x000D_
    "hobby": "swimming"_x000D_
    "name": "xyz",_x000D_
    "hobby": "programming"_x000D_

Why can't I define a default constructor for a struct in .NET?

Here's my solution to the no default constructor dilemma. I know this is a late solution, but I think it's worth noting this is a solution.

public struct Point2D {
    public static Point2D NULL = new Point2D(-1,-1);
    private int[] Data;

    public int X {
        get {
            return this.Data[ 0 ];
        set {
            try {
                this.Data[ 0 ] = value;
            } catch( Exception ) {
                this.Data = new int[ 2 ];
            } finally {
                this.Data[ 0 ] = value;

    public int Z {
        get {
            return this.Data[ 1 ];
        set {
            try {
                this.Data[ 1 ] = value;
            } catch( Exception ) {
                this.Data = new int[ 2 ];
            } finally {
                this.Data[ 1 ] = value;

    public Point2D( int x , int z ) {
        this.Data = new int[ 2 ] { x , z };

    public static Point2D operator +( Point2D A , Point2D B ) {
        return new Point2D( A.X + B.X , A.Z + B.Z );

    public static Point2D operator -( Point2D A , Point2D B ) {
        return new Point2D( A.X - B.X , A.Z - B.Z );

    public static Point2D operator *( Point2D A , int B ) {
        return new Point2D( B * A.X , B * A.Z );

    public static Point2D operator *( int A , Point2D B ) {
        return new Point2D( A * B.Z , A * B.Z );

    public override string ToString() {
        return string.Format( "({0},{1})" , this.X , this.Z );

ignoring the fact I have a static struct called null, (Note: This is for all positive quadrant only), using get;set; in C#, you can have a try/catch/finally, for dealing with the errors where a particular data type is not initialized by the default constructor Point2D(). I guess this is elusive as a solution to some people on this answer. Thats mostly why i'm adding mine. Using the getter and setter functionality in C# will allow you to bypass this default constructor non-sense and put a try catch around what you dont have initialized. For me this works fine, for someone else you might want to add some if statements. So, In the case where you would want a Numerator/Denominator setup, this code might help. I'd just like to reiterate that this solution does not look nice, probably works even worse from an efficiency standpoint, but, for someone coming from an older version of C#, using array data types gives you this functionality. If you just want something that works, try this:

public struct Rational {
    private long[] Data;

    public long Numerator {
        get {
            try {
                return this.Data[ 0 ];
            } catch( Exception ) {
                this.Data = new long[ 2 ] { 0 , 1 };
                return this.Data[ 0 ];
        set {
            try {
                this.Data[ 0 ] = value;
            } catch( Exception ) {
                this.Data = new long[ 2 ] { 0 , 1 };
                this.Data[ 0 ] = value;

    public long Denominator {
        get {
            try {
                return this.Data[ 1 ];
            } catch( Exception ) {
                this.Data = new long[ 2 ] { 0 , 1 };
                return this.Data[ 1 ];
        set {
            try {
                this.Data[ 1 ] = value;
            } catch( Exception ) {
                this.Data = new long[ 2 ] { 0 , 1 };
                this.Data[ 1 ] = value;

    public Rational( long num , long denom ) {
        this.Data = new long[ 2 ] { num , denom };
        /* Todo: Find GCD etc. */

    public Rational( long num ) {
        this.Data = new long[ 2 ] { num , 1 };
        this.Numerator = num;
        this.Denominator = 1;

C# : Passing a Generic Object

You'll have to provide more information about the generic type T. In your current PrintGeneric method, T might as well be a string, which does not have a var member.

You may want to change var to a property rather than a field

public interface ITest
    string var { get; }

And add a constraint where T: ITest to the PrintGeneric method.

Is there a function to copy an array in C/C++?

I like the answer of Ed S., but this only works for fixed size arrays and not when the arrays are defined as pointers.

So, the C++ solution where the arrays are defined as pointers:

const int bufferSize = 10;
char* origArray, newArray;
std::copy(origArray, origArray + bufferSize, newArray);

Note: No need to deduct buffersize with 1:

  1. Copies all elements in the range [first, last) starting from first and proceeding to last - 1


Javascript validation: Block special characters

A few of the options are deprecated as of today. So watch out for those.

If you try <input onkeypress="blockSpecialCharacters(event)" />, an IDE like WebStorm will slash out event and tell you:

Deprecated symbol used, consults docs for better alternative

Then when you get to the JavaScript, console.log(e.keyCode) will also give keyCode and say:

Deprecated symbol used, consults docs for better alternative

Anyways I did it using jQuery.

<script src=""></script>

<input id="theInput" />

    function blockSpecialCharacters(e) {
            let key = e.key;
            let keyCharCode = key.charCodeAt(0);

            // 0-9
            if(keyCharCode >= 48 && keyCharCode <= 57) {
                return key;
            // A-Z
            if(keyCharCode >= 65 && keyCharCode <= 90) {
                return key;
            // a-z
            if(keyCharCode >= 97 && keyCharCode <= 122) {
                return key;

            return false;

    $('#theInput').keypress(function(e) {

Switch statement fall-through...should it be allowed?

Fall-through is really a handy thing, depending on what you're doing. Consider this neat and understandable way to arrange options:

switch ($someoption) {
  case 'a':
  case 'b':
  case 'c':
    // Do something

  case 'd':
  case 'e':
    // Do something else

Imagine doing this with if/else. It would be a mess.

TypeError: 'float' object is not subscriptable

PriceList[0] is a float. PriceList[0][1] is trying to access the first element of a float. Instead, do

PriceList[0] = PriceList[1] = ...code omitted... = PriceList[6] = PizzaChange


PriceList[0:7] = [PizzaChange]*7

Validate phone number using javascript

function validatePhone(inputtxt) {_x000D_
  var phoneno = /^\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/;_x000D_
  return phoneno.test(inputtxt)_x000D_

Where is the Java SDK folder in my computer? Ubuntu 12.04

I found the solution to this with path name: /usr/lib/jvm/java-8-oracle

I'm on mint 18.1

Convert HashBytes to VarChar

Use master.dbo.fn_varbintohexsubstring(0, HashBytes('SHA1', @input), 1, 0) instead of master.dbo.fn_varbintohexstr and then substringing the result.

In fact fn_varbintohexstr calls fn_varbintohexsubstring internally. The first argument of fn_varbintohexsubstring tells it to add 0xF as the prefix or not. fn_varbintohexstr calls fn_varbintohexsubstring with 1 as the first argument internaly.

Because you don't need 0xF, call fn_varbintohexsubstring directly.

c - warning: implicit declaration of function ‘printf’

You need to include the appropriate header

#include <stdio.h>

If you're not sure which header a standard function is defined in, the function's man page will state this.

Receiving JSON data back from HTTP request

Building on @Panagiotis Kanavos' answer, here's a working method as example which will also return the response as an object instead of a string:

using System.Text;
using System.Net.Http;
using System.Threading.Tasks;
using Newtonsoft.Json; // Nuget Package

public static async Task<object> PostCallAPI(string url, object jsonObject)
        using (HttpClient client = new HttpClient())
            var content = new StringContent(jsonObject.ToString(), Encoding.UTF8, "application/json");
            var response = await client.PostAsync(url, content);
            if (response != null)
                var jsonString = await response.Content.ReadAsStringAsync();
                return JsonConvert.DeserializeObject<object>(jsonString);
    catch (Exception ex)
    return null;

Keep in mind that this is only an example and that you'd probably would like to use HttpClient as a shared instance instead of using it in a using-clause.

mysql Foreign key constraint is incorrectly formed error

mysql error texts doesn't help so much, in my case, the column had "not null" constraint, so the "on delete set null" was not allowed

Python - Check If Word Is In A String

This small function compares all search words in given text. If all search words are found in text, returns length of search, or False otherwise.

Also supports unicode string search.

def find_words(text, search):
    """Find exact words"""
    dText   = text.split()
    dSearch = search.split()

    found_word = 0

    for text_word in dText:
        for search_word in dSearch:
            if search_word == text_word:
                found_word += 1

    if found_word == len(dSearch):
        return lenSearch
        return False


find_words('çelik güray ankara', 'güray ankara')

Change Tomcat Server's timeout in Eclipse

SOLVED: That's it!!!! For me was compiling with JDK6 but running Tomcat with JDK7, WST uses the system properties and not the eclipse settings. I also configure the same JDK Version in eclipse and in System (check it with java -version in cmd line)

Details: I try to configure eclipse like describe here, but it didn´t solve the problem, then I notice in eclipse´s error log that tomcat was started with jre 1.7. in spite of my configurations.

I also try, in cmd line, 'java -version' and obtained '1.7' instead of expected '1.6'.

I also decide to configure java 1.6 (like in eclipse) in system panel but it didn´t solve the problem. I also desinstall jre 1.7 restart eclipse AND IT SUCCESS!.. It was a very usefull clue, thank you.

What is the best open XML parser for C++?

try this one:
it's easier and faster than RapidXML or PUGXML.
TinyXML is the worst of the "simple parser".

Split long commands in multiple lines through Windows batch file

You can break up long lines with the caret ^ as long as you remember that the caret and the newline following it are completely removed. So, if there should be a space where you're breaking the line, include a space. (More on that below.)


copy file1.txt file2.txt

would be written as:

copy file1.txt^

Git Remote: Error: fatal: protocol error: bad line length character: Unab

You can redirect any output from .bashrc to stderr:

# inside .bashrc
echo 'some error/warning/remind message' 1>&2

git will ignore this symbols

Error: "Could Not Find Installable ISAM"

Try putting single quotes around the data source:

Provider=Microsoft.Jet.OLEDB.4.0;Data Source='D:\ptdb\Program Tracking Database.mdb';

The problem tends to be white space which does have meaning to the parser.

If you had other attributes (e.g., Extended Properties), their values may also have to be enclosed in single quotes:

Provider=Microsoft.Jet.OLEDB.4.0;Data Source='D:\ptdb\Program Tracking Database.mdb'; Extended Properties='Excel 8.0;HDR=YES;IMEX=1;';

You could equally well use double quotes; however, you'll probably have to escape them, and I find that more of a Pain In The Algorithm than using singles.

Why an inline "background-image" style doesn't work in Chrome 10 and Internet Explorer 8?

u must specify the width and height also

 <section class="bg-solid-light slideContainer strut-slide-0" style="background-image: url(; background-repeat: no-repeat;width: 100%;height: 100%;" >

How to add google-services.json in Android?

  1. Download the "google-service.json" file from Firebase
  2. Go to this address in windows explorer "C:\Users\Your-Username\AndroidStudioProjects" You will see a list of your Android Studio projects
  3. Open a desired project, navigate to "app" folder and paste the .json file
  4. Go to Android Studio and click on "Sync with file system", located in dropdown menu (File>Sync with file system)
  5. Now sync with Gradle and everything should be fine

PHPmailer sending HTML CODE

do like this-paste your html code inside your separate html file using GET method.

    $mail->WordWrap = 70;                                 
    $mail->addAttachment= $_GET['addattachment']; $mail->AltBody   
    =$_GET['AltBody'];  $mail->Subject = $_GET['subject']; $mail->Body = $_GET['body'];

Check if one date is between two dates

Simplified way of doing this based on the accepted answer.

In my case I needed to check if current date (Today) is pithing the range of two other dates so used newDate() instead of hardcoded values but you can get the point how you can use hardcoded dates.

var currentDate = new Date().toJSON().slice(0,10);
var from = new Date('2020/01/01');
var to   = new Date('2020/01/31');
var check = new Date(currentDate);

console.log(check > from && check < to);

HTML input field hint

I have the same problem, and I have add this code to my application and its work fine for me.

step -1 : added the jquery.placeholder.js plugin

step -2 :write the below code in your area.

$(function () {
       $('input, textarea').placeholder();

And now I can see placeholders on the input boxes!

get Context in non-Activity class

If your class is non-activity class, and creating an instance of it from the activiy, you can pass an instance of context via constructor of the later as follows:

class YourNonActivityClass{

// variable to hold context
private Context context;

//save the context recievied via constructor in a local variable

public YourNonActivityClass(Context context){


You can create instance of this class from the activity as follows:

new YourNonActivityClass(this);

Unable to cast object of type 'System.DBNull' to type 'System.String`

This is the generic method that I use to convert any object that might be a DBNull.Value:

public static T ConvertDBNull<T>(object value, Func<object, T> conversionFunction)
    return conversionFunction(value == DBNull.Value ? null : value);


var result = command.ExecuteScalar();

return result.ConvertDBNull(Convert.ToInt32);


return command

how to add css class to html generic control div?

Alternative approach if you want to add a class to an existing list of classes of an element:

element.Attributes["class"] += " myCssClass";

Why use Ruby's attr_accessor, attr_reader and attr_writer?

You may use the different accessors to communicate your intent to someone reading your code, and make it easier to write classes which will work correctly no matter how their public API is called.

class Person
  attr_accessor :age

Here, I can see that I may both read and write the age.

class Person
  attr_reader :age

Here, I can see that I may only read the age. Imagine that it is set by the constructor of this class and after that remains constant. If there were a mutator (writer) for age and the class were written assuming that age, once set, does not change, then a bug could result from code calling that mutator.

But what is happening behind the scenes?

If you write:

attr_writer :age

That gets translated into:

def age=(value)
  @age = value

If you write:

attr_reader :age

That gets translated into:

def age

If you write:

attr_accessor :age

That gets translated into:

def age=(value)
  @age = value

def age

Knowing that, here's another way to think about it: If you did not have the attr_... helpers, and had to write the accessors yourself, would you write any more accessors than your class needed? For example, if age only needed to be read, would you also write a method allowing it to be written?

How to set bot's status

Bumping this all the way from 2018, sorry not sorry. But the newer users questioning how to do this need to know that game does not work anymore for this task.

    game: {
        name: 'with depression',
        type: "STREAMING",
        url: ""

does not work anymore. You will now need to do this:

    status: 'online',
    activity: {
        name: 'with depression',
        type: 'STREAMING',
        url: ''

This is referenced here as "game" is not a valid property of setPresence anymore. Read the PresenceData Documentation for more information about this.

Run multiple python scripts concurrently

I do this in node.js (on Windows 10) by opening 2 separate cmd instances and running each program in each instance.

This has the advantage that writing to the console is easily visible for each script.

I see that in python can do the same: 2 shells.

You can run multiple instances of IDLE/Python shell at the same time. So open IDLE and run the server code and then open up IDLE again, which will start a separate instance and then run your client code.

MVC - Set selected value of SelectList

Use LINQ and add the condition on the "selected" as a question mark condition.

    var listSiteId = (from site in db.GetSiteId().ToList()
                                      select new SelectListItem
                                          Value = site.SITEID,
                                          Text = site.NAME,
                                          Selected = (dimension.DISPLAYVALUE == site.SITEID) ? true : false,
                    ViewBag.SiteId = listSiteId;

Converting String array to java.util.List

List<String> strings = Arrays.asList(new String[]{"one", "two", "three"});

This is a list view of the array, the list is partly unmodifiable, you can't add or delete elements. But the time complexity is O(1).

If you want a modifiable a List:

List<String> strings = 
     new ArrayList<String>(Arrays.asList(new String[]{"one", "two", "three"}));

This will copy all elements from the source array into a new list (complexity: O(n))

How to refer to Excel objects in Access VBA?

Inside a module

Option Explicit
dim objExcelApp as Excel.Application
dim wb as Excel.Workbook

sub Initialize()
   set objExcelApp = new Excel.Application
end sub

sub ProcessDataWorkbook()
    dim ws as Worksheet
    set wb = objExcelApp.Workbooks.Open("path to my workbook")
    set ws = wb.Sheets(1)

    ws.Cells(1,1).Value = "Hello"
    ws.Cells(1,2).Value = "World"

    'Close the workbook
    set wb = Nothing
end sub

sub Release()
   set objExcelApp = Nothing
end sub

AngularJs: Reload page

<a title="Pending Employee Approvals" href="" ng-click="viewPendingApprovals(1)">
                    <i class="fa fa-user" aria-hidden="true"></i>
                    <span class="button_badge">{{pendingEmployeeApprovalCount}}</span>

and in the controller

 $scope.viewPendingApprovals = function(type) {
                if (window.location.hash.substring(window.location.hash.lastIndexOf('/') + 1, window.location.hash.length) == type) {
                } else {
                    $state.go("home.pendingApproval", { id: sessionStorage.typeToLoad });

and in the route file

.state('home.pendingApproval', {
        url: '/pendingApproval/:id',
        templateUrl: 'app/components/approvals/pendingApprovalList.html',
        controller: 'pendingApprovalListController'

So, If the id passed in the url is same as what is coming from the function called by clicking the anchor, then simply reload, else folow the requested route.

Please help me improve this answer, if this is helps. Any, suggestions are welcome.

CASE WHEN statement for ORDER BY clause

Another simple example from here..

SELECT * FROM dbo.Employee
 CASE WHEN Gender='Male' THEN EmployeeName END Desc,
 CASE WHEN Gender='Female' THEN Country END ASC

R for loop skip to next iteration ifelse

for(n in 1:5) {
  if(n==3) next # skip 3rd iteration and go to next iteration

What is the idiomatic Go equivalent of C's ternary operator?

One-liners, though shunned by the creators, have their place.

This one solves the lazy evaluation problem by letting you, optionally, pass functions to be evaluated if necessary:

func FullTernary(e bool, a, b interface{}) interface{} {
    if e {
        if reflect.TypeOf(a).Kind() == reflect.Func {
            return a.(func() interface{})()
        return a
    if reflect.TypeOf(b).Kind() == reflect.Func {
        return b.(func() interface{})()
    return b

func demo() {
    a := "hello"
    b := func() interface{} { return a + " world" }
    c := func() interface{} { return func() string { return "bye" } }
    fmt.Println(FullTernary(true, a, b).(string)) // cast shown, but not required
    fmt.Println(FullTernary(false, a, b))
    fmt.Println(FullTernary(true, b, a))
    fmt.Println(FullTernary(false, b, a))
    fmt.Println(FullTernary(true, c, nil).(func() string)())


hello world
hello world
  • Functions passed in must return an interface{} to satisfy the internal cast operation.
  • Depending on the context, you might choose to cast the output to a specific type.
  • If you wanted to return a function from this, you would need to wrap it as shown with c.

The standalone solution here is also nice, but could be less clear for some uses.

How to check if a String is numeric in Java

With Apache Commons Lang 3.5 and above: NumberUtils.isCreatable or StringUtils.isNumeric.

With Apache Commons Lang 3.4 and below: NumberUtils.isNumber or StringUtils.isNumeric.

You can also use StringUtils.isNumericSpace which returns true for empty strings and ignores internal spaces in the string. Another way is to use NumberUtils.isParsable which basically checks the number is parsable according to Java. (The linked javadocs contain detailed examples for each method.)

Calculating Time Difference

time.monotonic() (basically your computer's uptime in seconds) is guarranteed to not misbehave when your computer's clock is adjusted (such as when transitioning to/from daylight saving time).

>>> import time
>>> time.monotonic()
>>> a = time.monotonic()
>>> time.sleep(1)
>>> b = time.monotonic()
>>> print(b-a)

Android file chooser

I used AndExplorer for this purpose and my solution is popup a dialog and then redirect on the market to install the misssing application:

My startCreation is trying to call external file/directory picker. If it is missing call show installResultMessage function.

private void startCreation(){
    Intent intent = new Intent();
    Uri startDir = Uri.fromFile(new File("/sdcard"));

    intent.putExtra("browser_filter_extension_whitelist", "*.csv");
    intent.putExtra("explorer_title", getText(R.string.andex_file_selection_title));
    intent.putExtra("browser_list_fontscale", "120%");
    intent.putExtra("browser_list_layout", "2");

         ApplicationInfo info = getPackageManager()
                                 .getApplicationInfo("lysesoft.andexplorer", 0 );

            startActivityForResult(intent, PICK_REQUEST_CODE);
    } catch( PackageManager.NameNotFoundException e ){
    } catch (Exception e) {
        Log.w(TAG, e.getMessage());

This methos is just pick up a dialog and if user wants install the external application from market

private void showInstallResultMessage(int msg_id) {
    AlertDialog dialog = new AlertDialog.Builder(this).create();
            new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {
            new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {
                    Intent intent = new Intent(Intent.ACTION_VIEW);

Is there a Google Chrome-only CSS hack?

Only Chrome CSS hack:

@media all and (-webkit-min-device-pixel-ratio:0) and (min-resolution: .001dpcm) {
    #selector {
        background: red;

How to change href attribute using JavaScript after opening the link in a new window?

Is there any downside of leveraging mousedown listener to modify the href attribute with a new URL location and then let the browser figures out where it should redirect to?

It's working fine so far for me. Would like to know what the limitations are with this approach?

// Simple code snippet to demonstrate the said approach
const a = document.createElement('a');
a.textContent = 'test link';
a.href = '/haha'; = '_blank';
a.rel = 'noopener';

a.onmousedown = () => {
  a.href = '/lol';


Rounding float in Ruby

Pass an argument to round containing the number of decimal places to round to

>> 2.3465.round
=> 2
>> 2.3465.round(2)
=> 2.35
>> 2.3465.round(3)
=> 2.347

How might I schedule a C# Windows Service to perform a task daily?

Check out Quartz.NET. You can use it within a Windows service. It allows you to run a job based on a configured schedule, and it even supports a simple "cron job" syntax. I've had a lot of success with it.

Here's a quick example of its usage:

// Instantiate the Quartz.NET scheduler
var schedulerFactory = new StdSchedulerFactory();
var scheduler = schedulerFactory.GetScheduler();

// Instantiate the JobDetail object passing in the type of your
// custom job class. Your class merely needs to implement a simple
// interface with a single method called "Execute".
var job = new JobDetail("job1", "group1", typeof(MyJobClass));

// Instantiate a trigger using the basic cron syntax.
// This tells it to run at 1AM every Monday - Friday.
var trigger = new CronTrigger(
    "trigger1", "group1", "job1", "group1", "0 0 1 ? * MON-FRI");

// Add the job to the scheduler
scheduler.AddJob(job, true);

Add/delete row from a table

I would try formatting your table correctly first off like so:

I cannot help but thinking that formatting the table could at the very least not do any harm.


Check if DataRow exists by column name in c#?

if (row.Columns.Contains("US_OTHERFRIEND"))

How to detect string which contains only spaces?

The fastest solution would be using the regex prototype function test() and looking for any character that is not a space, tab, or line break \S :

if (!/\S/.test(str)) {
  // Didn't find something other than a space which means it's empty

In case you have a super long string, it can make a significant difference as it will stop processing as soon as it finds a non-space character.

ActiveModel::ForbiddenAttributesError when creating new user

Alternatively you can use the Protected Attributes gem, however this defeats the purpose of requiring strong params. However if you're upgrading an older app, Protected Attributes does provide an easy pathway to upgrade until such time that you can refactor the attr_accessible to strong params.

how to use concatenate a fixed string and a variable in Python

I know this is a little old but I wanted to add an updated answer with f-strings which were introduced in Python version 3.6:

msg['Subject'] = f'Auto Hella Restart Report {sys.argv[1]}'

Java parsing XML document gives "Content not allowed in prolog." error

Please check the xml file whether it has any junk character like this ?.If exists,please use the following syntax to remove that.

String XString = writer.toString();
XString = XString.replaceAll("[^\\x20-\\x7e]", "");

What are the most widely used C++ vector/matrix math/linear algebra libraries, and their cost and benefit tradeoffs?

Okay, I think I know what you're looking for. It appears that GGT is a pretty good solution, as Reed Copsey suggested.

Personally, we rolled our own little library, because we deal with rational points a lot - lots of rational NURBS and Beziers.

It turns out that most 3D graphics libraries do computations with projective points that have no basis in projective math, because that's what gets you the answer you want. We ended up using Grassmann points, which have a solid theoretical underpinning and decreased the number of point types. Grassmann points are basically the same computations people are using now, with the benefit of a robust theory. Most importantly, it makes things clearer in our minds, so we have fewer bugs. Ron Goldman wrote a paper on Grassmann points in computer graphics called "On the Algebraic and Geometric Foundations of Computer Graphics".

Not directly related to your question, but an interesting read.

Flask example with POST

Before actually answering your question:

Parameters in a URL (e.g. key=listOfUsers/user1) are GET parameters and you shouldn't be using them for POST requests. A quick explanation of the difference between GET and POST can be found here.

In your case, to make use of REST principles, you should probably have:


Then, on each URL, you can define the behaviour of different HTTP methods (GET, POST, PUT, DELETE). For example, on /users/<user_id>, you want the following:

GET /users/<user_id> - return the information for <user_id>
POST /users/<user_id> - modify/update the information for <user_id> by providing the data
PUT - I will omit this for now as it is similar enough to `POST` at this level of depth
DELETE /users/<user_id> - delete user with ID <user_id> 

So, in your example, you want do a POST to /users/user_1 with the POST data being "John". Then the XPath expression or whatever other way you want to access your data should be hidden from the user and not tightly couple to the URL. This way, if you decide to change the way you store and access data, instead of all your URL's changing, you will simply have to change the code on the server-side.

Now, the answer to your question: Below is a basic semi-pseudocode of how you can achieve what I mentioned above:

from flask import Flask
from flask import request

app = Flask(__name__)

@app.route('/users/<user_id>', methods = ['GET', 'POST', 'DELETE'])
def user(user_id):
    if request.method == 'GET':
        """return the information for <user_id>"""
    if request.method == 'POST':
        """modify/update the information for <user_id>"""
        # you can use <user_id>, which is a str but could
        # changed to be int or whatever you want, along
        # with your lxml knowledge to make the required
        # changes
        data = request.form # a multidict containing POST data
    if request.method == 'DELETE':
        """delete user with ID <user_id>"""
        # POST Error 405 Method Not Allowed

There are a lot of other things to consider like the POST request content-type but I think what I've said so far should be a reasonable starting point. I know I haven't directly answered the exact question you were asking but I hope this helps you. I will make some edits/additions later as well.

Thanks and I hope this is helpful. Please do let me know if I have gotten something wrong.

Get combobox value in Java swing

If the string is empty, comboBox.getSelectedItem().toString() will give a NullPointerException. So better to typecast by (String).

How to import existing Git repository into another?

See Basic example in this article and consider such mapping on repositories:

  • A <-> YYY,
  • B <-> XXX

After all activity described in this chapter (after merging), remove branch B-master:

$ git branch -d B-master

Then, push changes.

It works for me.

Example of SOAP request authenticated with WS-UsernameToken

The Hash Password Support and Token Assertion Parameters in Metro 1.2 explains very nicely what a UsernameToken with Digest Password looks like:

Digest Password Support

The WSS 1.1 Username Token Profile allows digest passwords to be sent in a wsse:UsernameToken of a SOAP message. Two more optional elements are included in the wsse:UsernameToken in this case: wsse:Nonce and wsse:Created. A nonce is a random value that the sender creates to include in each UsernameToken that it sends. A creation time is added to combine nonces to a "freshness" time period. The Password Digest in this case is calculated as:

Password_Digest = Base64 ( SHA-1 ( nonce + created + password ) )

This is how a UsernameToken with Digest Password looks like:

<wsse:UsernameToken wsu:Id="uuid_faf0159a-6b13-4139-a6da-cb7b4100c10c">
   <wsse:Password Type="">6S3P2EWNP3lQf+9VC3emNoT57oQ=</wsse:Password>
   <wsse:Nonce EncodingType="">YF6j8V/CAqi+1nRsGLRbuZhi</wsse:Nonce>

How do I find the location of my Python site-packages directory?

An additional note to the get_python_lib function mentioned already: on some platforms different directories are used for platform specific modules (eg: modules that require compilation). If you pass plat_specific=True to the function you get the site packages for platform specific packages.

JQuery, Spring MVC @RequestBody and JSON - making it work together

In case you are willing to use Curl for the calls with JSON 2 and Spring 3.2.0 in hand checkout the FAQ here. As AnnotationMethodHandlerAdapter is deprecated and replaced by RequestMappingHandlerAdapter.

What is the meaning of single and double underscore before an object name?

__foo__: this is just a convention, a way for the Python system to use names that won't conflict with user names.

_foo: this is just a convention, a way for the programmer to indicate that the variable is private (whatever that means in Python).

__foo: this has real meaning: the interpreter replaces this name with _classname__foo as a way to ensure that the name will not overlap with a similar name in another class.

No other form of underscores have meaning in the Python world.

There's no difference between class, variable, global, etc in these conventions.

What is the Angular equivalent to an AngularJS $watch?

Here is another approach using getter and setter functions for the model.

  selector: 'input-language',
  template: `
export class InputLanguageComponent {

  set query(value) {
    this._query = value;
    console.log('query set to :', value)

  get query() {
    return this._query;

Using group by and having clause

Having: It applies filter conditions to each group of rows. Where: It applies a filter of individual rows.

Could not instantiate mail function. Why this error occurring

I had the same error. The Reply-to was causing the problem. I removed it.

$email->AddReplyTo( $admin_email, $admin_name ); 

Android: How to open a specific folder via Intent and show its content in a file browser?

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(uri, DocumentsContract.Document.MIME_TYPE_DIR);

Will open files app home screen enter image description here

Get current date in Swift 3?

You can do it in this way with Swift 3.0:

let date = Date()
let calendar = Calendar.current
let components = calendar.dateComponents([.year, .month, .day], from: date)

let year =  components.year
let month = components.month
let day =


Returning pointer from a function

To my knowledge the use of the keyword new, does relatively the same thing as malloc(sizeof identifier). The code below demonstrates how to use the keyword new.

    void main(void){
        int* test;
        test = tester();
    int* tester(void){
        int *retMe;
        retMe = new int;//<----Here retMe is getting malloc for integer type
        *retMe = 12;<---- Initializes retMe... Note * dereferences retMe 
    return retMe;

wget ssl alert handshake failure

I was having this problem on Ubuntu 12.04.3 LTS (well beyond EOL, I know...) and got around it with:

sudo apt-get update && sudo apt-get install ca-certificates

How to reset all checkboxes using jQuery or pure JS?

<!DOCTYPE html>
<html lang="en">
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="">
  <script src=""></script>
  <script src=""></script>

<div class="container check">
<button class="btn">click</button>
  <input type="checkbox" name="vehicle" value="Bike">I have a bike<br>
<input type="checkbox" name="vehicle" value="Car">I have a car<br>
<input type="checkbox" name="vehicle" value="Bike">I have a bike<br>
<input type="checkbox" name="vehicle" value="Car">I have a car<br>
$('.btn').click(function() {

        this.checked = false; 

JavaScript: Upload file

Unless you're trying to upload the file using ajax, just submit the form to /upload/image.

<form enctype="multipart/form-data" action="/upload/image" method="post">
    <input id="image-file" type="file" />

If you do want to upload the image in the background (e.g. without submitting the whole form), you can use ajax:

How to pass macro definition from "make" command line arguments (-D) to C source code?

Call make this way

make CFLAGS=-Dvar=42

because you do want to override your Makefile's CFLAGS, and not just the environment (which has a lower priority with regard to Makefile variables).

Str_replace for multiple items

For example, if you want to replace search1 with replace1 and search2 with replace2 then following code will work:

print str_replace(
    array("replace1", "replace2"),
    "search1 search2"

// Output: replace1 replace2

jQuery Set Cursor Position in Text Area

Small modification to the code I found in bitbucket

Code is now able to select/highlight with start/end points if given 2 positions. Tested and works fine in FF/Chrome/IE9/Opera.

$('#field').caret(1, 9);

The code is listed below, only a few lines changed:

(function($) {
  $.fn.caret = function(pos) {
    var target = this[0];
    if (arguments.length == 0) { //get
      if (target.selectionStart) { //DOM
        var pos = target.selectionStart;
        return pos > 0 ? pos : 0;
      else if (target.createTextRange) { //IE
        var range = document.selection.createRange();
        if (range == null)
            return '0';
        var re = target.createTextRange();
        var rc = re.duplicate();
        rc.setEndPoint('EndToStart', re);
        return rc.text.length;
      else return 0;

    var pos_start = pos;
    var pos_end = pos;

    if (arguments.length > 1) {
        pos_end = arguments[1];

    if (target.setSelectionRange) //DOM
      target.setSelectionRange(pos_start, pos_end);
    else if (target.createTextRange) { //IE
      var range = target.createTextRange();
      range.moveEnd('character', pos_end);
      range.moveStart('character', pos_start);;

Importing PNG files into Numpy?

Using just scipy, glob and having PIL installed (pip install pillow) you can use scipy's imread method:

from scipy import misc
import glob

for image_path in glob.glob("/home/adam/*.png"):
    image = misc.imread(image_path)
    print image.shape
    print image.dtype


According to the doc, scipy.misc.imread is deprecated starting SciPy 1.0.0, and will be removed in 1.2.0. Consider using imageio.imread instead. See the answer by Charles.

includes() not working in all browsers

In my case i found better to use "".

var str = "Some very very very long string";
var n ="very");

In case it would be helpful for someone.

Capturing count from an SQL query

You'll get converting errors with:

cmd.CommandText = "SELECT COUNT(*) FROM table_name";
Int32 count = (Int32) cmd.ExecuteScalar();

Use instead:

string stm = "SELECT COUNT(*) FROM table_name WHERE id="+id+";";
MySqlCommand cmd = new MySqlCommand(stm, conn);
Int32 count = Convert.ToInt32(cmd.ExecuteScalar());
if(count > 0){
    found = true; 
} else {
    found = false; 

find path of current folder - cmd

Use This Code

@echo off
:: Get the current directory

for /f "tokens=* delims=/" %%A in ('cd') do set CURRENT_DIR=%%A


(echo this To confirm this code works fine)

Convert InputStream to JSONObject

InputStream inputStreamObject = PositionKeeperRequestTest.class.getResourceAsStream(jsonFileName);
JSONObject jsonObject = new JSONObject(IOUtils.toString(inputStreamObject));

Send HTML in email via PHP

Use PHPMailer,

To send HTML mail you have to set $mail->isHTML() only, and you can set your body with HTML tags

Here is a well written tutorial :

this.getClass().getClassLoader().getResource("...") and NullPointerException

I had the same issue with the following conditions:

  • The resource files are in the same package as the java source files, in the java source folder (src/test/java).
  • I build the project with maven on the command line and the build failed on the tests with the NullPointerException.
  • The command line build did not copy the resource files to the test-classes folder, which explained the build failure.
  • When going to eclipse after the command line build and rerun the tests in eclipse I also got the NullPointerException in eclipse.
  • When I cleaned the project (deleted the content of the target folder) and rebuild the project in Eclipse the test did run correctly. This explains why it runs when you start with a clean project.

I fixed this by placing the resource files in the resources folder in test: src/test/resources using the same package structure as the source class.

BTW I used getClass().getResource(...)

What is a LAMP stack?

For anyone still looking into this in order to learn specifically what a stack is, the term "stack" is referring to a "solution stack." A solution stack is simply a complete set of software to address a given problem, usually by combining to provide the platform or infrastructure necessary. This term is the parent of both "server stack" and "web stack." Accordingly, a LAMP stack is a specific and complete set of software specifically aimed at serving dynamic content over the web.

Some extra reading:

Where can I find documentation on formatting a date in JavaScript?

The Short Answer

There is no “universal” documentation that javascript caters to; every browser that has javascript is really an implementation. However, there is a standard that most modern browsers tend to follow, and that’s the EMCAScript standard; the ECMAScript standard strings would take, minimally, a modified implementation of the ISO 8601 definition.

In addition to this, there is a second standard set forward by the IETF that browsers tend to follow as well, which is the definition for timestamps made in the RFC 2822. Actual documentation can be found in the references list at the bottom.

From this you can expect basic functionality, but what “ought” to be is not inherently what “is”. I’m going to go a little in depth with this procedurally though, as it appears only three people actually answered the question (Scott, goofballLogic, and peller namely) which, to me, suggests most people are unaware of what actually happens when you create a Date object.

The Long Answer

Where is the documentation which lists the format specifiers supported by the Date() object?

To answer the question, or typically even look for the answer to this question, you need to know that javascript is not a novel language; it’s actually an implementation of ECMAScript, and follows the ECMAScript standards (but note, javascript also actually pre-dated those standards; EMCAScript standards are built off the early implementation of LiveScript/JavaScript). The current ECMAScript standard is 5.1 (2011); at the time that the question was originally asked (June ’09), the standard was 3 (4 was abandoned), but 5 was released shortly after the post at the end of 2009. This should outline one problem; what standard a javascript implementation may follow, may not reflect what is actually in place, because a) it’s an implementation of a given standard, b) not all implementations of a standard are puritan, and c) functionality is not released in synchronization with a new standard as d) an implementation is a constant work in progress

Essentially, when dealing with javascript, you’re dealing with a derivative (javascript specific to the browser) of an implementation (javascript itself). Google’s V8, for example, implements ECMAScript 5.0, but Internet Explorer’s JScript doesn’t attempt to conform to any ECMAScript standard, yet Internet Explorer 9 does conform to ECMAScript 5.0.

When a single argument is passed to new Date(), it casts this function prototype:

new Date(value)

When two or more arguments are passed to new Date(), it casts this function prototype:

new Date (year, month [, date [, hours [, minutes [, seconds [, ms ] ] ] ] ] )

Both of those functions should look familiar, but this does not immediately answer your question and what quantifies as an acceptable “date format” requires further explanation. When you pass a string to new Date(), it will call the prototype (note that I'm using the word prototype loosely; the versions may be individual functions, or it may be part of a conditional statement in a single function) for new Date(value) with your string as the argument for the “value” parameter. This function will first check whether it is a number or a string. The documentation for this function can be found here:

From this, we can deduce that to get the string formatting allowed for new Date(value), we have to look at the method Date.parse(string). The documentation for this method can be found here:

And we can further infer that dates are expected to be in a modified ISO 8601 Extended Format, as specified here:

However, we can recognize from experience that javascript’s Date object accepts other formats (enforced by the existence of this question in the first place), and this is okay because ECMAScript allows for implementation specific formats. However, that still doesn’t answer the question of what documentation is available on the available formats, nor what formats are actually allowed. We’re going to look at Google’s javascript implementation, V8; please note I’m not suggesting this is the “best” javascript engine (how can one define “best” or even “good”) and one cannot assume that the formats allowed in V8 represent all formats available today, but I think it’s fair to assume they do follow modern expectations.

Google’s V8, date.js, DateConstructor

Looking at the DateConstructor function, we can deduce we need to find the DateParse function; however, note that “year” is not the actual year and is only a reference to the “year” parameter.

Google’s V8, date.js, DateParse

This calls %DateParseString, which is actually a run-time function reference for a C++ function. It refers to the following code:

Google’s V8,, %DateParseString

The function call we’re concerned with in this function is for DateParser::Parse(); ignore the logic surrounding those function calls, these are just checks to conform to the encoding type (ASCII and UC16). DateParser::Parse is defined here:

Google's V8, dateparser-inl.h, DateParser::Parse

This is the function that actually defines what formats it accepts. Essentially, it checks for the EMCAScript 5.0 ISO 8601 standard and if it is not standards compliant, then it will attempt to build the date based on legacy formats. A few key points based on the comments:

  1. Words before the first number that are unknown to the parser are ignored.
  2. Parenthesized text are ignored.
  3. Unsigned numbers followed by “:” are interpreted as a “time component”.
  4. Unsigned numbers followed by “.” are interpreted as a “time component”, and must be followed by milliseconds.
  5. Signed numbers followed by the hour or hour minute (e.g. +5:15 or +0515) are interpreted as the timezone.
  6. When declaring the hour and minute, you can use either “hh:mm” or “hhmm”.
  7. Words that indicate a time zone are interpreted as a time zone.
  8. All other numbers are interpreted as “date components”.
  9. All words that start with the first three digits of a month are interpreted as the month.
  10. You can define minutes and hours together in either of the two formats: “hh:mm” or “hhmm”.
  11. Symbols like “+”, “-“ and unmatched “)” are not allowed after a number has been processed.
  12. Items that match multiple formats (e.g. 1970-01-01) are processed as a standard compliant EMCAScript 5.0 ISO 8601 string.

So this should be enough to give you a basic idea of what to expect when it comes to passing a string into a Date object. You can further expand upon this by looking at the following specification that Mozilla points to on the Mozilla Developer Network (compliant to the IETF RFC 2822 timestamps):

The Microsoft Developer Network additionally mentions an additional standard for the Date object: ECMA-402, the ECMAScript Internationalization API Specification, which is complementary to the ECMAScript 5.1 standard (and future ones). That can be found here:

In any case, this should aid in highlighting that there is no "documentation" that universally represents all implementations of javascript, but there is still enough documentation available to make reasonable sense of what strings are acceptable for a Date object. Quite the loaded question when you think about it, yes? :P



What's the best way to detect a 'touch screen' device using JavaScript?

When a mouse is attached, it can be assumed with fairly high hitrate (I would say practially 100%) that the user moves the mouse at least a tiny distance after page is ready - without any clicking. The mechanism below detects this. If detected, I consider this as a sign of missing touch support or, if supported, of minor importance when a mouse is in use. Touch-device is assumed if not detected.

EDIT This approach may not fit all purposes. It can be used to control functionality that is activated based on user interaction on the loaded page, for instance an image viewer. The code below will also leave the mousemove event bound on devices without mouse as it stands out now. Other approaches may be better.

Roughly, it goes like this (sorry for jQuery, but similar in pure Javascript):

var mousedown, first, second = false;
var ticks = 10;
$(document).on('mousemove', (function(e) {
    if(UI.mousechecked) return;
    if(!first) {
        first = e.pageX;
    if(!second && ticks-- === 0) {
        second = e.pageX;
        $(document).off('mousemove'); // or bind it to somewhat else
    if(first  && second  && first !== second && !mousedown){
        // set whatever flags you want
        UI.hasmouse = true;
        UI.touch = false;
        UI.mousechecked = true;

$(document).one('mousedown', (function(e) {
    mousedown = true;
$(document).one('mouseup', (function(e) {
    mousedown = false;

ERROR 2003 (HY000): Can't connect to MySQL server on '' (111)

look at the my.cnf file, if there contain [client] section, and the port is other than real listen port (default 3306), you must connect the server with explicit parameter -P 3306, e.g.

mysql -u root -h -p -P 3306

How to draw in JPanel? (Swing/graphics Java)

When working with graphical user interfaces, you need to remember that drawing on a pane is done in the Java AWT/Swing event queue. You can't just use the Graphics object outside the paint()/paintComponent()/etc. methods.

However, you can use a technique called "Frame buffering". Basically, you need to have a BufferedImage and draw directly on it (see it's createGraphics() method; that graphics context you can keep and reuse for multiple operations on a same BufferedImage instance, no need to recreate it all the time, only when creating a new instance). Then, in your JPanel's paintComponent(), you simply need to draw the BufferedImage instance unto the JPanel. Using this technique, you can perform zoom, translation and rotation operations quite easily through affine transformations.

How to browse localhost on Android device?

You can get a public URL for your server running on a specific port on localhost.

At my work place I could access the local server by using the local IP address of my machine in the app, as most of the other answers suggest. But at home I wasn't able to do that for some reason. After trying many answers and spending many hours, I came across It is pretty straight forward. Just download it from within the folder do:

ngrok portnumber

( from command prompt in windows)

./ngrok portnumber

(from terminal in linux)

This will give you a public URL for your local server running on that port number on localhost. You can include in your app and debug it using that URL.

You can securely expose a local web server to the internet and capture all traffic for detailed inspection. You can share the URL with your colleague developer also who might be working remotely and can debug the App/Server interaction.

Hope this saves someone's time someday.

How to check for an empty struct?

Just a quick addition, because I tackled the same issue today:

With Go 1.13 it is possible to use the new isZero() method:

if reflect.ValueOf(session).IsZero() {
     // do stuff...

I didn't test this regarding performance, but I guess that this should be faster, than comparing via reflect.DeepEqual().

How many bytes is unsigned long long?

It must be at least 64 bits. Other than that it's implementation defined.

Strictly speaking, unsigned long long isn't standard in C++ until the C++0x standard. unsigned long long is a 'simple-type-specifier' for the type unsigned long long int (so they're synonyms).

The long long set of types is also in C99 and was a common extension to C++ compilers even before being standardized.

How to manually reload Google Map with JavaScript

You can refresh with this:

map.panBy(0, 0);

SQL Query - Concatenating Results into One String

@AlexanderMP's answer is correct, but you can also consider handling nulls with coalesce:

declare @CodeNameString  nvarchar(max)
set @CodeNameString = null
SELECT @CodeNameString = Coalesce(@CodeNameString + ', ', '') + cast(CodeName as varchar) from AccountCodes  
select @CodeNameString

Center/Set Zoom of Map to cover all visible Markers?

The size of array must be greater than zero. ?therwise you will have unexpected results.

function zoomeExtends(){
  var bounds = new google.maps.LatLngBounds();
  if (markers.length>0) { 
      for (var i = 0; i < markers.length; i++) {

How to trust a apt repository : Debian apt-get update error public key is not available: NO_PUBKEY <id>

I found several posts telling me to run several gpg commands, but they didn't solve the problem because of two things. First, I was missing the debian-keyring package on my system and second I was using an invalid keyserver. Try different keyservers if you're getting timeouts!

Thus, the way I fixed it was:

apt-get install debian-keyring
gpg --keyserver --recv-keys 1F41B907
gpg --armor --export 1F41B907 | apt-key add -

Then running a new "apt-get update" worked flawlessly!

Why does Google prepend while(1); to their JSON responses?

After authentication is in place, JSON hijacking protection can take a variety of forms. Google appends while(1) into their JSON data, so that if any malicious script evaluates it, the malicious script enters an infinite loop.

Reference: Web Security Testing Cookbook: Systematic Techniques to Find Problems Fast

Get Cell Value from a DataTable in C#

You can iterate DataTable like this:

private void button1_Click(object sender, EventArgs e)
    for(int i = 0; i< dt.Rows.Count;i++)
        for (int j = 0; j <dt.Columns.Count ; j++)
            object o = dt.Rows[i].ItemArray[j];
            //if you want to get the string
            //string s = o = dt.Rows[i].ItemArray[j].ToString();

Depending on the type of the data in the DataTable cell, you can cast the object to whatever you want.

Vagrant shared and synced folders

shared folders VS synced folders

Basically shared folders are renamed to synced folder from v1 to v2 (docs), under the bonnet it is still using vboxsf between host and guest (there is known performance issues if there are large numbers of files/directories).

Vagrantfile directory mounted as /vagrant in guest

Vagrant is mounting the current working directory (where Vagrantfile resides) as /vagrant in the guest, this is the default behaviour.

See docs

NOTE: By default, Vagrant will share your project directory (the directory with the Vagrantfile) to /vagrant.

You can disable this behaviour by adding cfg.vm.synced_folder ".", "/vagrant", disabled: true in your Vagrantfile.

Why synced folder is not working

Based on the output /tmp on host was NOT mounted during up time.

Use VAGRANT_INFO=debug vagrant up or VAGRANT_INFO=debug vagrant reload to start the VM for more output regarding why the synced folder is not mounted. Could be a permission issue (mode bits of /tmp on host should be drwxrwxrwt).

I did a test quick test using the following and it worked (I used opscode bento raring vagrant base box)

config.vm.synced_folder "/tmp", "/tmp/src"


$ vagrant reload
[default] Attempting graceful shutdown of VM...
[default] Setting the name of the VM...
[default] Clearing any previously set forwarded ports...
[default] Creating shared folders metadata...
[default] Clearing any previously set network interfaces...
[default] Available bridged network interfaces:
1) eth0
2) vmnet8
3) lxcbr0
4) vmnet1
What interface should the network bridge to? 1
[default] Preparing network interfaces based on configuration...
[default] Forwarding ports...
[default] -- 22 => 2222 (adapter 1)
[default] Running 'pre-boot' VM customizations...
[default] Booting VM...
[default] Waiting for VM to boot. This can take a few minutes.
[default] VM booted and ready for use!
[default] Configuring and enabling network interfaces...
[default] Mounting shared folders...
[default] -- /vagrant
[default] -- /tmp/src

Within the VM, you can see the mount info /tmp/src on /tmp/src type vboxsf (uid=900,gid=900,rw).

Access props inside quotes in React JSX

Note: In react you can put javascript expression inside curly bracket. We can use this property in this example.
Note: give one look to below example:

class LoginForm extends React.Component {

  constructor(props) {

    this.state = {i:1};

  handleClick() {
    this.setState(prevState => ({i : prevState.i + 1}));


  render() {

    return (
        <p onClick={this.handleClick.bind(this)}>Click to change image</p>
        <img src={'images/back'+ this.state.i+'.jpg'}/>


How to send control+c from a bash script?

ctrl+c and kill -INT <pid> are not exactly the same, to emulate ctrl+c we need to first understand the difference.

kill -INT <pid> will send the INT signal to a given process (found with its pid).

ctrl+c is mapped to the intr special character which when received by the terminal should send INT to the foreground process group of that terminal. You can emulate that by targetting the group of your given <pid>. It can be done by prepending a - before the signal in the kill command. Hence the command you want is:

kill -INT -<pid>

You can test it pretty easily with a script:

#!/usr/bin/env ruby

fork {
    trap(:INT) {
        puts 'signal received in child!'
    sleep 1_000

puts "run `kill -INT -#{}` in any other terminal window."


Emulating a do-while loop in Bash

Place the body of your loop after the while and before the test. The actual body of the while loop should be a no-op.

    #do other stuff
    (( current_time <= cutoff ))

Instead of the colon, you can use continue if you find that more readable. You can also insert a command that will only run between iterations (not before first or after last), such as echo "Retrying in five seconds"; sleep 5. Or print delimiters between values:

i=1; while printf '%d' "$((i++))"; (( i <= 4)); do printf ','; done; printf '\n'

I changed the test to use double parentheses since you appear to be comparing integers. Inside double square brackets, comparison operators such as <= are lexical and will give the wrong result when comparing 2 and 10, for example. Those operators don't work inside single square brackets.

Stylesheet not updating

I ran into this problem too, a lot of people seem to recommend force reloading your page, which won't fix the issue in cases such as if you're running it on a server. I believe the optimal solution in this scenario is to timestamp your css.

  1. This is how I do it in my Django template:

<link rel="stylesheet" href="{% static 'home/radioStyles.css' %}?{% now 'U' %}" type="text/css"/>

Where adding ?{% now 'U' %} to the end of your css file would fix this issue.

  1. How you would do it with just CSS (hopefully someone edits this to a cleaner version, this looks a little janky but it does work, tested it):

<link rel="stylesheet" type="text/css" href="style.css?Wednesday 2nd February 2020 12PM" />

Where ?Wednesday 2nd February 2020 12PM (current date) seems to fix the issue, I also noticed just putting the time fixes it too.

MySQL error 1449: The user specified as a definer does not exist

in my case I had a trigger on that table that I could not update data getting the same error.

MySQL error 1449: The user specified as a definer does not exist

the solution was to delete the triggers on that table and recreate them again, this fixed the issue, since the the trigger was made with another user from another server, and the user name changed on the new server after changing hosting company . that's my 2 cents

Using isKindOfClass with Swift

I would use:

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {

    super.touchesBegan(touches, withEvent: event)
    let touch : UITouch = touches.anyObject() as UITouch

    if let touchView = touch.view as? UIPickerView


Correct way to initialize HashMap and can HashMap hold different value types?

The 2nd one is using generics which came in with Java 1.5. It will reduce the number of casts in your code & can help you catch errors at compiletime instead of runtime. That said, it depends on what you are coding. A quick & dirty map to hold a few objects of various types doesn't need generics. But if the map is holding objects all descending from a type other than Object, it can be worth it.

The prior poster is incorrect about the array in a map. An array is actually an object, so it is a valid value.

Map<String,Object> map = new HashMap<String,Object>();
map.put("one",1); // autoboxed to an object
map.put("two", new int[]{1,2} ); // array of ints is an object
map.put("three","hello"); // string is an object

Also, since HashMap is an object, it can also be a value in a HashMap.

How to make bootstrap column height to 100% row height?

@Alan's answer will do what you're looking for, but this solution fails when you use the responsive capabilities of Bootstrap. In your case, you're using the xs sizes so you won't notice, but if you used anything else (e.g. col-sm, col-md, etc), you'd understand.

Another approach is to play with margins and padding. See the updated fiddle:

.left-side {
  background-color: blue;
  padding-bottom: 1000px;
  margin-bottom: -1000px;
  height: 100%;
.something {
  height: 100%;
  background-color: red;
  padding-bottom: 1000px;
  margin-bottom: -1000px;
  height: 100%;
.row {
  background-color: green;
  overflow: hidden;

JavaScript console.log causes error: "Synchronous XMLHttpRequest on the main thread is deprecated..."

In my case this was caused by the flexie script which was part of the "CDNJS Selections" app offered by Cloudflare.

According to Cloudflare "This app is being deprecated in March 2015". I turned it off and the message disappeared instantly.

You can access the apps by visiting

NB: this is a copy of my answer on this thread Synchronous XMLHttpRequest warning and <script> (I visited both when looking for a solution)

When using a Settings.settings file in .NET, where is the config actually stored?

It depends on whether the setting you have chosen is at "User" scope or "Application" scope.

User scope

User scope settings are stored in

C:\Documents and Settings\ username \Local Settings\Application Data\ ApplicationName

You can read/write them at runtime.

For Vista and Windows 7, folder is

C:\Users\ username \AppData\Local\ ApplicationName


C:\Users\ username \AppData\Roaming\ ApplicationName

Application scope

Application scope settings are saved in AppName.exe.config and they are readonly at runtime.

Vertically align text within a div

Try this:




div {
    height: 100px;

span {
    height: 100px;
    display: table-cell;
    vertical-align: middle;

How does Java import work?

Java's import statement is pure syntactical sugar. import is only evaluated at compile time to indicate to the compiler where to find the names in the code.

You may live without any import statement when you always specify the full qualified name of classes. Like this line needs no import statement at all:

javax.swing.JButton but = new  javax.swing.JButton();

The import statement will make your code more readable like this:

import javax.swing.*;

JButton but = new JButton();

How to select top n rows from a datatable/dataview in ASP.NET

Data view is good Feature of data table . We can filter the data table as per our requirements using data view . Below Functions is After binding data table to list box data source then filter by text box control . ( this condition you can change as per your needs .Contains(txtSearch.Text.Trim()) )

Private Sub BindClients()

   okcl = 0

    sql = "Select * from Client Order By cname"        
    Dim dacli As New SqlClient.SqlDataAdapter
    Dim cmd As New SqlClient.SqlCommand()
    cmd.CommandText = sql
    cmd.CommandType = CommandType.Text
    dacli.SelectCommand = cmd
    dacli.SelectCommand.Connection = Me.sqlcn
    Dim dtcli As New DataTable
    lstboxc.DataSource = dataTableClients
    lstboxc.DisplayMember = "cname"
    lstboxc.ValueMember = "ccode"
    okcl = 1

    If dtcli.Rows.Count > 0 Then
        ccode = dtcli.Rows(0)("ccode")
        Call ClientDispData1()
    End If
End Sub

Private Sub FilterClients()        

    Dim query As EnumerableRowCollection(Of DataRow) = From dataTableClients In 
    dataTableClients.AsEnumerable() Where dataTableClients.Field(Of String) 
    ("cname").Contains(txtSearch.Text.Trim()) Order By dataTableClients.Field(Of 
    String)("cname") Select dataTableClients

    Dim dataView As DataView = query.AsDataView()
    lstboxc.DataSource = dataView
    lstboxc.DisplayMember = "cname"
    lstboxc.ValueMember = "ccode"
    okcl = 1
    If dataTableClients.Rows.Count > 0 Then
        ccode = dataTableClients.Rows(0)("ccode")
        Call ClientDispData1()
    End If
End Sub

How to delete a selected DataGridViewRow and update a connected database table?

maybe you can use temp list for delete. for ignore row index change

private void btnDelete_Click(object sender, EventArgs e)_x000D_
    List<int> wantdel = new List<int>();_x000D_
    foreach (DataGridViewRow row in dataGridView1.Rows)_x000D_
        if ((bool)row.Cells["Select"].Value == true)_x000D_
    wantdel.OrderByDescending(y => y).ToList().ForEach(x =>_x000D_
    });           _x000D_

How I can delete in VIM all text from current line to end of file?

Go to the first line from which you would like to delete, and press the keys dG

Why do we have to specify FromBody and FromUri?

The default behavior is:

  1. If the parameter is a primitive type (int, bool, double, ...), Web API tries to get the value from the URI of the HTTP request.

  2. For complex types (your own object, for example: Person), Web API tries to read the value from the body of the HTTP request.

So, if you have:

  • a primitive type in the URI, or
  • a complex type in the body

...then you don't have to add any attributes (neither [FromBody] nor [FromUri]).

But, if you have a primitive type in the body, then you have to add [FromBody] in front of your primitive type parameter in your WebAPI controller method. (Because, by default, WebAPI is looking for primitive types in the URI of the HTTP request.)

Or, if you have a complex type in your URI, then you must add [FromUri]. (Because, by default, WebAPI is looking for complex types in the body of the HTTP request by default.)

Primitive types:

public class UsersController : ApiController
    // api/users
    public HttpResponseMessage Post([FromBody]int id)

    // api/users/id
    public HttpResponseMessage Post(int id)


Complex types:

public class UsersController : ApiController
    // api/users
    public HttpResponseMessage Post(User user)


    // api/users/user
    public HttpResponseMessage Post([FromUri]User user)


This works as long as you send only one parameter in your HTTP request. When sending multiple, you need to create a custom model which has all your parameters like this:

public class MyModel
    public string MyProperty { get; set; }
    public string MyProperty2 { get; set; }

public async Task<dynamic> Search([FromBody] MyModel model)
    // model.MyProperty;
    // model.MyProperty2;

From Microsoft's documentation for parameter binding in ASP.NET Web API:

When a parameter has [FromBody], Web API uses the Content-Type header to select a formatter. In this example, the content type is "application/json" and the request body is a raw JSON string (not a JSON object). At most one parameter is allowed to read from the message body.

This should work:

public HttpResponseMessage Post([FromBody] string name) { ... }

This will not work:

// Caution: This won't work!    
public HttpResponseMessage Post([FromBody] int id, [FromBody] string name) { ... }

The reason for this rule is that the request body might be stored in a non-buffered stream that can only be read once.

Using OR in SQLAlchemy

This has been really helpful. Here is my implementation for any given table:

def sql_replace(self, tableobject, dictargs):

    #missing check of table object is valid
    primarykeys = [ for key in inspect(tableobject).primary_key]

    filterargs = []
    for primkeys in primarykeys:
        if dictargs[primkeys] is not None:
            filterargs.append(getattr(db.RT_eqmtvsdata, primkeys) == dictargs[primkeys])

    query = select([db.RT_eqmtvsdata]).where(and_(*filterargs))

    if self.r_ExecuteAndErrorChk2(query)[primarykeys[0]] is not None:
        # update
        filter = and_(*filterargs)
        query = tableobject.__table__.update().values(dictargs).where(filter)
        return self.w_ExecuteAndErrorChk2(query)

        query = tableobject.__table__.insert().values(dictargs)
        return self.w_ExecuteAndErrorChk2(query)

# example usage
inrow = {'eqmtvs_id': eqmtvsid, 'datetime': dtime, 'param_id': paramid}

self.sql_replace(tableobject=db.RT_eqmtvsdata, dictargs=inrow)

Best way to extract a subvector from a vector?

You could just use insert

vector<type> myVec { n_elements };

vector<type> newVec;

newVec.insert(newVec.begin(), myVec.begin() + X, myVec.begin() + Y);

How to get value of selected radio button?

var rates = document.getElementById('rates').value;

The rates element is a div, so it won't have a value. This is probably where the undefined is coming from.

The checked property will tell you whether the element is selected:

if (document.getElementById('r1').checked) {
  rate_value = document.getElementById('r1').value;

How can I remove an element from a list?

If you don't want to modify the list in-place (e.g. for passing the list with an element removed to a function), you can use indexing: negative indices mean "don't include this element".

x <- list("a", "b", "c", "d", "e"); # example list

x[-2];       # without 2nd element

x[-c(2, 3)]; # without 2nd and 3rd

Also, logical index vectors are useful:

x[x != "b"]; # without elements that are "b"

This works with dataframes, too:

df <- data.frame(number = 1:5, name = letters[1:5])

df[df$name != "b", ];     # rows without "b"

df[df$number %% 2 == 1, ] # rows with odd numbers only

What is the difference between a stored procedure and a view?

A view represents a virtual table. You can join multiple tables in a view and use the view to present the data as if the data were coming from a single table.

A stored procedure uses parameters to do a function... whether it is updating and inserting data, or returning single values or data sets.

Creating Views and Stored Procedures - has some information from Microsoft as to when and why to use each.

Say I have two tables:

  • tbl_user, with columns: user_id, user_name, user_pw
  • tbl_profile, with columns: profile_id, user_id, profile_description

So, if I find myself querying from those tables A LOT... instead of doing the join in EVERY piece of SQL, I would define a view like:

CREATE VIEW vw_user_profile
  SELECT A.user_id, B.profile_description
  FROM tbl_user A LEFT JOIN tbl_profile B ON A.user_id = b.user_id

Thus, if I want to query profile_description by user_id in the future, all I have to do is:

SELECT profile_description FROM vw_user_profile WHERE user_id = @ID

That code could be used in a stored procedure like:

    @ID int
    SELECT profile_description FROM vw_user_profile WHERE user_id = @ID

So, later on, I can call:

dbo.getDesc 25

and I will get the description for user_id 25, where the 25 is your parameter.

There is obviously a lot more detail, this is just the basic idea.

MySQL ON DUPLICATE KEY UPDATE for multiple rows insert in single query

You can use Replace instead of INSERT ... ON DUPLICATE KEY UPDATE.

PSEXEC, access denied errors

I just added "-?" parameter. It makes Psexec copy executable to remote machine. So it works without access errors.

iPhone App Minus App Store?

Official Developer Program

For a standard iPhone you'll need to pay the US$99/yr to be a member of the developer program. You can then use the adhoc system to install your application onto up to 100 devices. The developer program has the details but it involves adding UUIDs for each of the devices to your application package. UUIDs can be easiest retrieved using Ad Hoc Helper available from the App Store. For further details on this method, see Craig Hockenberry's Beta testing on iPhone 2.0 article

Jailbroken iPhone

For jailbroken iPhones, you can use the following method which I have personally tested using the AccelerometerGraph sample app on iPhone OS 3.0.

Create Self-Signed Certificate

First you'll need to create a self signed certificate and patch your iPhone SDK to allow the use of this certificate:

  1. Launch Keychain With no items selected, from the Keychain menu select Certificate Assistant, then Create a Certificate.

    Name: iPhone Developer
    Certificate Type: Code Signing
    Let me override defaults: Yes

  2. Click Continue

    Validity: 3650 days

  3. Click Continue

  4. Blank out the Email address field.

  5. Click Continue until complete.

    You should see "This root certificate is not trusted". This is expected.

  6. Set the iPhone SDK to allow the self-signed certificate to be used:

    sudo /usr/bin/sed -i .bak 's/XCiPhoneOSCodeSignContext/XCCodeSignContext/' /Developer/Platforms/iPhoneOS.platform/Info.plist

    If you have Xcode open, restart it for this change to take effect.

Manual Deployment over WiFi

The following steps require openssh, and uikittools to be installed first. Replace jasoniphone.local with the hostname of the target device. Be sure to set your own password on both the mobile and root users after installing SSH.

To manually compile and install your application on the phone as a system app (bypassing Apple's installation system):

  1. Project, Set Active SDK, Device and Set Active Build Configuration, Release.

  2. Compile your project normally (using Build, not Build & Go).

  3. In the build/Release-iphoneos directory you will have an app bundle. Use your preferred method to transfer this to /Applications on the device.

    scp -r root@jasoniphone:/Applications/

  4. Let SpringBoard know the new application has been installed:

    ssh [email protected] uicache

    This only has to be done when you add or remove applications. Updated applications just need to be relaunched.

To make life easier for yourself during development, you can setup SSH key authentication and add these extra steps as a custom build step in your project.

Note that if you wish to remove the application later you cannot do so via the standard SpringBoard interface and you'll need to use SSH and update the SpringBoard:

ssh [email protected] rm -r /Applications/ &&
ssh [email protected] uicache

NameError: name 'python' is not defined

It looks like you are trying to start the Python interpreter by running the command python.

However the interpreter is already started. It is interpreting python as a name of a variable, and that name is not defined.

Try this instead and you should hopefully see that your Python installation is working as expected:

print("Hello world!")

How to compare numbers in bash?

The bracket stuff (e.g., [[ $a -gt $b ]] or (( $a > $b )) ) isn't enough if you want to use float numbers as well; it would report a syntax error. If you want to compare float numbers or float number to integer, you can use (( $(bc <<< "...") )).

For example,


if (( $(bc <<<"$a > $b") )); then 
    echo "a is greater than b"
    echo "a is not greater than b"

You can include more than one comparison in the if statement. For example,


if (( $(bc <<<"$b == $c && $b < $a") )); then 
    echo "b is equal to c but less than a"
    echo "b is either not equal to c and/or not less than a"

That's helpful if you want to check if a numeric variable (integer or not) is within a numeric range.

Taking multiple inputs from user in python

You can try this.

import sys

for line in sys.stdin:
    j= int(line[0])
    e= float(line[1])
    t= str(line[2])

For details, please review,

How to execute an Oracle stored procedure via a database link

for me, this worked

exec utl_mail.send@myotherdb(
  sender => '[email protected]',recipients => '[email protected], 
  cc => null, subject => 'my subject', message => 'my message'

Excel: replace part of cell's string value

What you need to do is as follows:

  1. List item
  2. Select the entire column by clicking once on the corresponding letter or by simply selecting the cells with your mouse.
  3. Press Ctrl+H.
  4. You are now in the "Find and Replace" dialog. Write "Author" in the "Find what" text box.
  5. Write "Authoring" in the "Replace with" text box.
  6. Click the "Replace All" button.

That's it!

phpmailer - The following SMTP Error: Data not accepted

I was hitting this error with phpMailer + Amazon SES. The phpMailer error is not very descriptive:

2: message: SERVER -> CLIENT: 554 Transaction failed: Expected ';', got "\"
1: message: 
2: message: SMTP Error: data not accepted.

For me the issue was simply that I had the following as content type:

$phpmailer->ContentType = 'text/html; charset=utf-8\r\n';

But that it shouldn't have the linebreak in it:

$phpmailer->ContentType = 'text/html; charset=utf-8';

... I suspect this was legacy code from our older version. So basically, triple check every $phpmailer setting you're adding - the smallest detail counts.

jQuery selector first td of each row

try this selector -


Demo -->


$("tr td:first-child")

Demo -->

</td>foobar</td> should be <td>foobar</td>

Oracle - How to create a readonly user

It is not strictly possible in default db due to the many public executes that each user gains automatically through public.

Execute a shell function with timeout

As Douglas Leeder said you need a separate process for timeout to signal to. Workaround by exporting function to subshells and running subshell manually.

export -f echoFooBar
timeout 10s bash -c echoFooBar

MySQL add days to a date

This query stands good for fetching the values between current date and its next 3 dates

SELECT * FROM tableName

This will eventually add extra 3 days of buffer to the current date.

When to use malloc for char pointers

Use malloc() when you don't know the amount of memory needed during compile time. In case if you have read-only strings then you can use const char* str = "something"; . Note that the string is most probably be stored in a read-only memory location and you'll not be able to modify it. On the other hand if you know the string during compiler time then you can do something like: char str[10]; strcpy(str, "Something"); Here the memory is allocated from stack and you will be able to modify the str. Third case is allocating using malloc. Lets say you don'r know the length of the string during compile time. Then you can do char* str = malloc(requiredMem); strcpy(str, "Something"); free(str);

SQL not a single-group group function

Maybe you find this simpler

select * from (
    select ssn, sum(time) from downloads
    group by ssn
    order by sum(time) desc
) where rownum <= 10 --top 10 downloaders


How to load/reference a file as a File instance from the classpath

This also works, and doesn't require a /path/to/file URI conversion. If the file is on the classpath, this will find it.

File currFile = new File(getClass().getClassLoader().getResource("the_file.txt").getFile());

how to add button click event in android studio

Start your OnClickListener, but when you get to the first set up parenthesis, type new, then View, and press enter. Should look like this when you're done:

Button btn1 = (Button)findViewById(;

btn1.setOnClickListener(new View.OnClickListener() {            
    public void onClick(View v) {
//your stuff here.

Flattening a shallow list in Python

If you have to flat a more complicated list with not iterable elements or with depth more than 2 you can use following function:

def flat_list(list_to_flat):
    if not isinstance(list_to_flat, list):
        yield list_to_flat
        for item in list_to_flat:
            yield from flat_list(item)

It will return a generator object which you can convert to a list with list() function. Notice that yield from syntax is available starting from python3.3, but you can use explicit iteration instead.

>>> a = [1, [2, 3], [1, [2, 3, [1, [2, 3]]]]]
>>> print(list(flat_list(a)))
[1, 2, 3, 1, 2, 3, 1, 2, 3]


You have to define a table alias for a derived table in SQL Server:

        SELECT * FROM TABLE2) x

"x" is the table alias in this example.

Specified cast is not valid.. how to resolve this

Use Convert.ToDouble(value) rather than (double)value. It takes an object and supports all of the types you asked for! :)

Also, your method is always returning a string in the code above; I'd recommend having the method indicate so, and give it a more obvious name (public string FormatLargeNumber(object value))

How are booleans formatted in Strings in Python?

You may also use the Formatter class of string

print "{0} {1}".format(True, False);
print "{0:} {1:}".format(True, False);
print "{0:d} {1:d}".format(True, False);
print "{0:f} {1:f}".format(True, False);
print "{0:e} {1:e}".format(True, False);

These are the results

True False
True False
1 0
1.000000 0.000000
1.000000e+00 0.000000e+00

Some of the %-format type specifiers (%r, %i) are not available. For details see the Format Specification Mini-Language

What are the main differences between JWT and OAuth authentication?

JWT is an open standard that defines a compact and self-contained way for securely transmitting information between parties. It is an authentication protocol where we allow encoded claims (tokens) to be transferred between two parties (client and server) and the token is issued upon the identification of a client. With each subsequent request we send the token.

Whereas OAuth2 is an authorization framework, where it has a general procedures and setups defined by the framework. JWT can be used as a mechanism inside OAuth2.

You can read more on this here

OAuth or JWT? Which one to use and why?

How to show Alert Message like "successfully Inserted" after inserting to DB using MVC3

The 'best' way to do this would be to set a property on a view object once the update is successful. You can then access this property in the view and inform the user accordingly.

Having said that it would be possible to trigger an alert from the controller code by doing something like this -

public ActionResult ActionName(PostBackData postbackdata)
    //your DB code
    return new JavascriptResult { Script = "alert('Successfully registered');" };

You can find further info in this question - How to display "Message box" using MVC3 controller

Error message "Linter pylint is not installed"

I would like to add my trials and my solution following rob3c's answer.

PS: My solution only concerns Windows users.

The problem:

I tried the following settings without success:

// settings.json
"python.linting.pylintPath": ${workspaceFolder}\\_tools\\python3\\Scripts\\pylint


"python.linting.pylintPath": ${workspaceFolder}\\_tools\\python3\\Scripts\\pylint.exe

I always had the following error message:

Linter 'pylint' is not installed. Please install it or select another linter".
Error: spawn c:\WS\myproject\_tools\python3\Scripts\pylint ENOENT

Even with a pylint file in my folder:

dir c:\WS\myproject\_tools\python3\Scripts\
05.07.2017  09:34 AM                52 pylint    # ! no pylint.exe !

As my toolchain is based on MSYS, the Pylint installed is without pylint.exe.

The content of _tools\python3\Scripts\pylint file:

from pylint import run_pylint

The solution

My workaround was to create a batch file .vscode\pylint.bat with the following contents:

%PYTHON3_EXE% _prefix\python3\Scripts\pylint %*

(%PYTHON3_EXE% is an environment variable to the Python 3 interpreter C:\Python34\python.exe)

And to configure .vscode\settings.json as follows:

// settings.json
"python.linting.pylintPath": "${workspaceFolder}\\.vscode\\pylint.bat",


Log from OUTPUT --> Python:

##########Linting Output - pylint##########

c:\WS\myproject> C:\Python34\python.exe _tools\python3\Scripts\pylint
--rcfile c:\WS\framework\pylintrc
Using config file c:\WS\myproject\pylintrc


Your code has been rated at 10.00/10

? Visual Studio Code uses the Pylint version from my toolchain!

C++ obtaining milliseconds time on Linux -- clock() doesn't seem to work properly

#include <sys/time.h>
#include <stdio.h>
#include <unistd.h>
int main()
    struct timeval start, end;

    long mtime, seconds, useconds;    

    gettimeofday(&start, NULL);
    gettimeofday(&end, NULL);

    seconds  = end.tv_sec  - start.tv_sec;
    useconds = end.tv_usec - start.tv_usec;

    mtime = ((seconds) * 1000 + useconds/1000.0) + 0.5;

    printf("Elapsed time: %ld milliseconds\n", mtime);

    return 0;

Best radio-button implementation for IOS

I've written a controller for handling the logic behind an array of radio buttons. It's open source and on GitHub, check it out!

How can I align all elements to the left in JPanel?

My favorite method to use would be the BorderLayout method. Here are the five examples with each position the component could go in. The example is for if the component were a button. We will add it to a JPanel, p. The button will be called b.

//To align it to the left
p.add(b, BorderLayout.WEST);

//To align it to the right
p.add(b, BorderLayout.EAST);

//To align it at the top
p.add(b, BorderLayout.NORTH);

//To align it to the bottom
p.add(b, BorderLayout.SOUTH);

//To align it to the center
p.add(b, BorderLayout.CENTER);

Don't forget to import it as well by typing:

import java.awt.BorderLayout;

There are also other methods in the BorderLayout class involving things like orientation, but you can do your own research on that if you curious about that. I hope this helped!

How to set image in imageview in android?

1> You can add image from layout itself:

                android:padding="2dp" />


2> Programmatically in java class:

ImageView ivYouImage= (ImageView)findViewById(;

OR for fragments:

View rowView= inflater.inflate(R.layout.your_layout, null, true);

ImageView ivYouImage= (ImageView) rowView.findViewById(;

Remove last specific character in a string c#

When you have spaces at the end. you can use beliow.

ProcessStr = ProcessStr.Replace(" ", "");
Emails     = ProcessStr.TrimEnd(';');

convert string date to java.sql.Date

worked for me too:

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
    Date parsed = null;
    try {
        parsed = sdf.parse("02/01/2014");
    } catch (ParseException e1) {
        // TODO Auto-generated catch block
    java.sql.Date data = new java.sql.Date(parsed.getTime());
    contato.setDataNascimento( data);

    // Contato DataNascimento era Calendar

    // grave nessa conexão!!! 
    ContatoDao dao = new ContatoDao("mysql");           

    // método elegante 
    System.out.println("Banco: ["+dao.getNome()+"] Gravado! Data: "+contato.getDataNascimento());

How to comment multiple lines with space or indent

One way to do it would be:

  1. Select the text, Press CTRL + K, C to comment (CTRL+E+C )
  2. Move the cursor to the first line after the delimiter // and before the Code text.
  3. Press Alt + Shift and use arrow keys to make selection. (Remember to make line selection(using down, up arrow keys), not the text selection - See Box Selection and Multi line editing)
  4. Once the selection is done, press space bar to enter a single space.

Notice the vertical blue line in the below image( that will appear once the selection is made, then you can insert any number of characters in between them)

enter image description here

I couldn't find a direct way to do that. The interesting thing is that it is mentioned in the C# Coding Conventions (C# Programming Guide) under Commenting Conventions.

Insert one space between the comment delimiter (//) and the comment text

But the default implementation of commenting in visual studio doesn't insert any space

Accessing Arrays inside Arrays In PHP

You can access the inactive tags array with (assuming $myArray contains the array)


Your question doesn't seem to go beyond accessing the contents of the inactiveTags key so I can only speculate with what your final goal is.

The first key:value pair in the inactiveTags array is

array ('195' => array(
                 'id' => 195, 
                 'tag' => 'auto')

To access the tag value, you would use

$myArray['inactiveTags'][195]['tag']; // auto

If you want to loop through each inactiveTags element, I would suggest:

foreach($myArray['inactiveTags'] as $value) {
  print $value['id'];
  print $value['tag'];

This will print all the id and tag values for each inactiveTag

Edit:: For others to see, here is a var_dump of the array provided in the question since it has not readible

  'languages' => 
      76 => 
          'id' => string '76' (length=2)
          'tag' => string 'Deutsch' (length=7)
  'targets' => 
      81 => 
          'id' => string '81' (length=2)
          'tag' => string 'Deutschland' (length=11)
  'tags' => 
      7866 => 
          'id' => string '7866' (length=4)
          'tag' => string 'automobile' (length=10)
      17800 => 
          'id' => string '17800' (length=5)
          'tag' => string 'seat leon' (length=9)
      17801 => 
          'id' => string '17801' (length=5)
          'tag' => string 'seat leon cupra' (length=15)
  'inactiveTags' => 
      195 => 
          'id' => string '195' (length=3)
          'tag' => string 'auto' (length=4)
      17804 => 
          'id' => string '17804' (length=5)
          'tag' => string 'coupès' (length=6)
      17805 => 
          'id' => string '17805' (length=5)
          'tag' => string 'fahrdynamik' (length=11)
      901 => 
          'id' => string '901' (length=3)
          'tag' => string 'fahrzeuge' (length=9)
      17802 => 
          'id' => string '17802' (length=5)
          'tag' => string 'günstige neuwagen' (length=17)
      1991 => 
          'id' => string '1991' (length=4)
          'tag' => string 'motorsport' (length=10)
      2154 => 
          'id' => string '2154' (length=4)
          'tag' => string 'neuwagen' (length=8)
      10660 => 
          'id' => string '10660' (length=5)
          'tag' => string 'seat' (length=4)
      17803 => 
          'id' => string '17803' (length=5)
          'tag' => string 'sportliche ausstrahlung' (length=23)
      74 => 
          'id' => string '74' (length=2)
          'tag' => string 'web 2.0' (length=7)
  'categories' => 
      16082 => 
          'id' => string '16082' (length=5)
          'tag' => string 'Auto & Motorrad' (length=15)
      51 => 
          'id' => string '51' (length=2)
          'tag' => string 'Blogosphäre' (length=11)
      66 => 
          'id' => string '66' (length=2)
          'tag' => string 'Neues & Trends' (length=14)
      68 => 
          'id' => string '68' (length=2)
          'tag' => string 'Privat' (length=6)

How do I send an HTML Form in an Email .. not just MAILTO

> 2020 Answer = The Easy Way using Google Apps Script (5 Mins)

We had a similar challenge to solve yesterday, and we solved it using a Google Apps Script!

Send Email From an HTML Form Without a Backend (Server) via Google!

The solution takes 5 mins to implement and I've documented with step-by-step instructions:

Brief Overview

A. Using the sample script, deploy a Google App Script

Deploy the sample script as a Google Spreadsheet APP Script: google-script-just-email.js


remember to set the TO_ADDRESS in the script to where ever you want the emails to be sent.
and copy the APP URL so you can use it in the next step when you publish the script.

B. Create your HTML Form and Set the action to the App URL

Using the sample html file: index.html create a basic form.


remember to paste your APP URL into the form action in the HTML form.

C. Test the HTML Form in your Browser

Open the HTML Form in your Browser, Input some data & submit it!

html form

Submit the form. You should see a confirmation that it was sent: form sent

Open the inbox for the email address you set (above)

email received


Everything about this is customisable, you can easily style/theme the form with your favourite CSS Library and Store the submitted data in a Google Spreadsheet for quick analysis.
The complete instructions are available on GitHub:

Returning from a void function

The first way is "more correct", what intention could there be to express? If the code ends, it ends. That's pretty clear, in my opinion.

I don't understand what could possibly be confusing and need clarification. If there's no looping construct being used, then what could possibly happen other than that the function stops executing?

I would be severly annoyed by such a pointless extra return statement at the end of a void function, since it clearly serves no purpose and just makes me feel the original programmer said "I was confused about this, and now you can be too!" which is not very nice.

How to split a string into a list?

How about this algorithm? Split text on whitespace, then trim punctuation. This carefully removes punctuation from the edge of words, without harming apostrophes inside words such as we're.

>>> text
"'Oh, you can't help that,' said the Cat: 'we're all mad here. I'm mad. You're mad.'"

>>> text.split()
["'Oh,", 'you', "can't", 'help', "that,'", 'said', 'the', 'Cat:', "'we're", 'all', 'mad', 'here.', "I'm", 'mad.', "You're", "mad.'"]

>>> import string
>>> [word.strip(string.punctuation) for word in text.split()]
['Oh', 'you', "can't", 'help', 'that', 'said', 'the', 'Cat', "we're", 'all', 'mad', 'here', "I'm", 'mad', "You're", 'mad']

Finding what methods a Python object has

import moduleName
for x in dir(moduleName):

This should work :)

Excel formula to get cell color

As commented, just in case the link I posted there broke, try this:

Add a Name(any valid name) in Excel's Name Manager under Formula tab in the Ribbon.
Then assign a formula using GET.CELL function.


63 stands for backcolor.
Let's say we name it Background so in any cell with color type:


enter image description here

Notice that Cells A2, A3 and A4 returns 3, 4, and 5 respectively which equates to the cells background color index. HTH.
BTW, here's a link on Excel's Color Index

Java using enum with switch statement

I am doing it like

public enum State
    // Retrieving, // the MediaRetriever is retrieving music //
    Stopped, // media player is stopped and not prepared to play
    Preparing, // media player is preparing...
    Playing, // playback active (media player ready!). (but the media player
                // may actually be
                // paused in this state if we don't have audio focus. But we
                // stay in this state
                // so that we know we have to resume playback once we get
                // focus back)
    Paused; // playback paused (media player ready!)

    //public final static State[] vals = State.values();//copy the values(), calling values() clones the array


public State getState()
        return mState;   

And use in Switch Statement

switch (mService.getState())
case Stopped:
case Paused:


case Preparing:
case Playing: