Programs & Examples On #Value objects

Python: OSError: [Errno 2] No such file or directory: ''

Use os.path.abspath():


sys.argv[0] in your case is just a script name, no directory, so os.path.dirname() returns an empty string.

os.path.abspath() turns that into a proper absolute path with directory name.

Apache POI error loading XSSFWorkbook class

commons-collections4-x.x.jar definitely solve this problem but Apache has removed the Interface ListValuedMap from commons-Collections4-4.0.jar so use updated version 4.1 it has the required classes and Interfaces.

Refer here if you want to read Excel (2003 or 2007+) using java code.

(Excel) Conditional Formatting based on Adjacent Cell Value

You need to take out the $ signs before the row numbers in the formula....and the row number used in the formula should correspond to the first row of data, so if you are applying this to the ("applies to") range $B$2:$B$5 it must be this formula


by using that "relative" version rather than your "absolute" one Excel (implicitly) adjusts the formula for each row in the range, as if you were copying the formula down

How to increase IDE memory limit in IntelliJ IDEA on Mac?

Helpful trick I thought I'd share on this old thread.

You can see how much memory is being used and adjust things accordingly using the Show memory indicator setting.

enter image description here

It shows up in the lower right of the window.

enter image description here

Installing Numpy on 64bit Windows 7 with Python 2.7.3

Try the (unofficial) binaries in this site:

You can get the newest numpy x64 with or without Intel MKL libs for Python 2.7 or Python 3.

How to change symbol for decimal point in double.ToString()?

If you have an Asp.Net web application, you can also set it in the web.config so that it is the same throughout the whole web application


getting error while updating Composer

A lot of good answers already for Ubuntu. I'm on Linux and had the same problem but none of the commands above worked for me.

With Linux and php70 I used the following command which worked great:

sudo yum install php70-mbstring -y

How to query data out of the box using Spring data JPA by both Sort and Pageable?

In my case, to use Pageable and Sorting at the same time I used like below. In this case I took all elements using pagination and sorting by id by descending order:

modelRepository.findAll(PageRequest.of(page, 10,"id").descending()))

Like above based on your requirements you can sort data with 2 columns as well.

Add rows to CSV File in powershell

Simple to me is like this:

$Time = Get-Date -Format "yyyy-MM-dd HH:mm K"
$Description = "Done on time"

"$Time,$Description"|Add-Content -Path $File # Keep no space between content variables

If you have a lot of columns, then create a variable like $NewRow like:

$Time = Get-Date -Format "yyyy-MM-dd HH:mm K"
$Description = "Done on time"
$NewRow = "$Time,$Description" # No space between variables, just use comma(,).

$NewRow | Add-Content -Path $File # Keep no space between content variables

Please note the difference between Set-Content (overwrites the existing contents) and Add-Content (appends to the existing contents) of the file.

Getting pids from ps -ef |grep keyword


ps -ef | grep "KEYWORD" | awk '{print $2}'

That command should give you the PID of the processes with KEYWORD in them. In this instance, awk is returning what is in the 2nd column from the output.

MySQL Insert query doesn't work with WHERE clause

If you are specifying a particular record no for inserting data its better to use UPDATE statement instead of INSERT statement.

This type of query you have written in the question is like a dummy query.

Your Query is :-

INSERT INTO Users( weight, desiredWeight ) VALUES ( 160, 145 ) WHERE id = 1;

Here , you are specifying the id=1 , so better you use UPDATE statement to update the existing record.It is not recommended to use WHERE clause in case of INSERT.You should use UPDATE .

Now Using Update Query :-

UPDATE Users SET weight=160,desiredWeight=145 WHERE id=1;

adding 30 minutes to datetime php/mysql

Use DATE_ADD function


Check if not nil and not empty in Rails shortcut?

There's a method that does this for you:

def show
  @city =

The present? method tests for not-nil plus has content. Empty strings, strings consisting of spaces or tabs, are considered not present.

Since this pattern is so common there's even a shortcut in ActiveRecord:

def show
  @city =

This is roughly equivalent.

As a note, testing vs nil is almost always redundant. There are only two logically false values in Ruby: nil and false. Unless it's possible for a variable to be literal false, this would be sufficient:

if (variable)
  # ...

This is preferable to the usual if (!variable.nil?) or if (variable != nil) stuff that shows up occasionally. Ruby tends to wards a more reductionist type of expression.

One reason you'd want to compare vs. nil is if you have a tri-state variable that can be true, false or nil and you need to distinguish between the last two states.

Ansible: how to get output to display

Every Ansible task when run can save its results into a variable. To do this, you have to specify which variable to save the results into. Do this with the register parameter, independently of the module used.

Once you save the results to a variable you can use it later in any of the subsequent tasks. So for example if you want to get the standard output of a specific task you can write the following:

- hosts: localhost
    - shell: ls
      register: shell_result

    - debug:
        var: shell_result.stdout_lines

Here register tells ansible to save the response of the module into the shell_result variable, and then we use the debug module to print the variable out.

An example run would look like the this:

PLAY [localhost] ***************************************************************

TASK [command] *****************************************************************
changed: [localhost]

TASK [debug] *******************************************************************
ok: [localhost] => {
    "shell_result.stdout_lines": [

Responses can contain multiple fields. stdout_lines is one of the default fields you can expect from a module's response.

Not all fields are available from all modules, for example for a module which doesn't return anything to the standard out you wouldn't expect anything in the stdout or stdout_lines values, however the msg field might be filled in this case. Also there are some modules where you might find something in a non-standard variable, for these you can try to consult the module's documentation for these non-standard return values.

Alternatively you can increase the verbosity level of ansible-playbook. You can choose between different verbosity levels: -v, -vvv and -vvvv. For example when running the playbook with verbosity (-vvv) you get this:

PLAY [localhost] ***************************************************************

TASK [command] *****************************************************************
changed: [localhost] => {
    "changed": true,
    "cmd": "ls",
    "delta": "0:00:00.007621",
    "end": "2017-02-17 23:04:41.912570",
    "invocation": {
        "module_args": {
            "_raw_params": "ls",
            "_uses_shell": true,
            "chdir": null,
            "creates": null,
            "executable": null,
            "removes": null,
            "warn": true
        "module_name": "command"
    "rc": 0,
    "start": "2017-02-17 23:04:41.904949",
    "stderr": "",
    "stdout": "play.retry\nplay.yml",
    "stdout_lines": [
    "warnings": []

As you can see this will print out the response of each of the modules, and all of the fields available. You can see that the stdout_lines is available, and its contents are what we expect.

To answer your main question about the jenkins_script module, if you check its documentation, you can see that it returns the output in the output field, so you might want to try the following:

  - jenkins_script:
      script: (...)
    register: jenkins_result

  - debug:
      var: jenkins_result.output

Setting Authorization Header of HttpClient

In the case you want to send HttpClient request with Bearer Token, this code can be a good solution:

var requestMessage = new HttpRequestMessage
    Method = HttpMethod.Post,
    Content = new StringContent(".....", Encoding.UTF8, "application/json"),
    RequestUri = new Uri(".....")

requestMessage.Headers.Authorization = new AuthenticationHeaderValue("Bearer", "Your token");

var response = await _httpClient.SendAsync(requestMessage);

How can I determine if a date is between two dates in Java?

You might want to take a look at Joda Time which is a really good API for dealing with date/time. Even though if you don't really need it for the solution to your current question it is bound to save you pain in the future.

How to abort makefile if variable not set?

Use the shell function test:

    test $(something)


$ make foo
Makefile:2: recipe for target 'foo' failed
make: *** [foo] Error 1
$ make foo something=x
test x

Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

Type in the terminal as follows:

mysql.server start

How do I delete an entity from symfony2

Symfony is smart and knows how to make the find() by itself :

public function deleteGuestAction(Guest $guest)
    if (!$guest) {
        throw $this->createNotFoundException('No guest found');

    $em = $this->getDoctrine()->getEntityManager();

    return $this->redirect($this->generateUrl('GuestBundle:Page:viewGuests.html.twig'));

To send the id in your controller, use {{ path('your_route', {'id':}) }}

How to get status code from webclient?

You should be able to use the "client.ResponseHeaders[..]" call, see this link for examples of getting stuff back from the response

Add (insert) a column between two columns in a data.frame

When you can not assume that column b comes before c you can use match to find the column number of both, min to get the lower column number and seq_len to get a sequence until this column. Then you can use this index first as a positive subset, than place the new column d and then use the sequence again as a negative subset.

i <- seq_len(min(match(c("b", "c"), colnames(x))))
data.frame(x[i], d, x[-i])
#cbind(x[i], d, x[-i]) #Alternative
#  a b  d c
#1 1 4 10 7
#2 2 5 11 8
#3 3 6 12 9

In case you know that column b comes before c you can place the new column d after b:

i <- seq_len(match("b", colnames(x)))
data.frame(x[i], d, x[-i])
#  a b  d c
#1 1 4 10 7
#2 2 5 11 8
#3 3 6 12 9


x <- data.frame(a = 1:3, b = 4:6, c = 7:9)
d <- 10:12

Reload content in modal (twitter bootstrap)

You can force Modal to refresh the popup by adding this line at the end of the hide method of the Modal plugin (If you are using bootstrap-transition.js v2.1.1, it should be at line 836)


Or with an event listener

$('#modal').on('hidden', function() {

Auto increment in phpmyadmin

@AmitKB, Your procedure is correct. Although this error

Query error: #1075 - Incorrect table definition; there can be only one auto column and it must be defined as a key

can be solved by first marking the field as key(using the key icon with label primary),unless you have other key then it may not work.

How to run an application as "run as administrator" from the command prompt?

It looks like psexec -h is the way to do this:

 -h         If the target system is Windows Vista or higher, has the process
            run with the account's elevated token, if available.

Which... doesn't seem to be listed in the online documentation in Sysinternals - PsExec.

But it works on my machine.

JavaScript - Get Portion of URL Path

If this is the current url use window.location.pathname otherwise use this regular expression:

var reg = /.+?\:\/\/.+?(\/.+?)(?:#|\?|$)/;
var pathname = reg.exec( '' )[1];

Python 3.1.1 string to hex

In Python 3, all strings are unicode. Usually, if you encode an unicode object to a string, you use .encode('TEXT_ENCODING'), since hex is not a text encoding, you should use codecs.encode() to handle arbitrary codecs. For example:

>>>> "hello".encode('hex')
LookupError: 'hex' is not a text encoding; use codecs.encode() to handle arbitrary codecs
>>>> import codecs
>>>> codecs.encode(b"hello", 'hex')

Again, since "hello" is unicode, you need to indicate it as a byte string before encoding to hexadecimal. This may be more inline with what your original approach of using the encode method.

The differences between binascii.hexlify and codecs.encode are as follow:

  • binascii.hexlify

    Hexadecimal representation of binary data.

    The return value is a bytes object.

    Type: builtin_function_or_method

  • codecs.encode

    encode(obj, [encoding[,errors]]) -> object

    Encodes obj using the codec registered for encoding. encoding defaults to the default encoding. errors may be given to set a different error handling scheme. Default is 'strict' meaning that encoding errors raise a ValueError. Other possible values are 'ignore', 'replace' and 'xmlcharrefreplace' as well as any other name registered with codecs.register_error that can handle ValueErrors.

    Type: builtin_function_or_method

In Excel, how do I extract last four letters of a ten letter string?

No need to use a macro. Supposing your first string is in A1.

=RIGHT(A1, 4)

Drag this down and you will get your four last characters.

Edit: To be sure, if you ever have sequences like 'ABC DEF' and want the last four LETTERS and not CHARACTERS you might want to use trimspaces()


Edit: As per brettdj's suggestion, you may want to check that your string is actually 4-character long or more:


What is log4j's default log file dumping path

You can see the log info in the console view of your IDE if you are not using any log4j properties to generate log file. You can define in your project so that those properties would be used to generate log file. A quick sample is listed below.

# Global logging configuration
log4j.rootLogger=DEBUG, stdout, R

# SQL Map logging configuration... MapClientDelegate=INFO


# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n


# Keep one backup file

log4j.appender.R.layout.ConversionPattern=%d %5p [%t] (%F\:%L) - %m%n

How to delete shared preferences data from App in Android

The Kotlin ktx way to clear all preferences:

val prefs: SharedPreferences = getSharedPreferences("prefsName", Context.MODE_PRIVATE)
prefs.edit(commit = true) {

Click here for all Shared preferences operations with examples

Convert string to number field

Within Crystal, you can do it by creating a formula that uses the ToNumber function. It might be a good idea to code for the possibility that the field might include non-numeric data - like so:

If NumericText ({field}) then ToNumber ({field}) else 0

Alternatively, you might find it easier to convert the field's datatype within the query used in the report.

"Non-static method cannot be referenced from a static context" error

setLoanItem() isn't a static method, it's an instance method, which means it belongs to a particular instance of that class rather than that class itself.

Essentially, you haven't specified what media object you want to call the method on, you've only specified the class name. There could be thousands of media objects and the compiler has no way of knowing what one you meant, so it generates an error accordingly.

You probably want to pass in a media object on which to call the method:

public void loanItem(Media m) {

Convert unsigned int to signed int C

@Mysticial got it. A short is usually 16-bit and will illustrate the answer:

int main()  
    unsigned int x = 65529;
    int y = (int) x;
    printf("%d\n", y);

    unsigned short z = 65529;
    short zz = (short)z;
    printf("%d\n", zz);

Press any key to continue . . .

A little more detail. It's all about how signed numbers are stored in memory. Do a search for twos-complement notation for more detail, but here are the basics.

So let's look at 65529 decimal. It can be represented as FFF9h in hexadecimal. We can also represent that in binary as:

11111111 11111001

When we declare short zz = 65529;, the compiler interprets 65529 as a signed value. In twos-complement notation, the top bit signifies whether a signed value is positive or negative. In this case, you can see the top bit is a 1, so it is treated as a negative number. That's why it prints out -7.

For an unsigned short, we don't care about sign since it's unsigned. So when we print it out using %d, we use all 16 bits, so it's interpreted as 65529.

Why doesn't document.addEventListener('load', function) work in a greasemonkey script?

Apparently, document.addEventListener() is unreliable, and hence, my error. Use window.addEventListener() with the same parameters, instead.

how to change a selections options based on another select option selected?

Here is my simple solution using Jquery filters.

$('#publisher').on('change', function(e) {
   let selector = $(this).val();
   $("#site > option").hide();
   $("#site > option").filter(function(){return $(this).data('pub') == selector}).show();


Nginx upstream prematurely closed connection while reading response header from upstream, for large requests

You can increase the timeout in node like so.'/slow/request', function(req, res){ req.connection.setTimeout(100000); //100 seconds ... }

Forcing to download a file using PHP

Here is a more browser-safe solution:

    $fp = @fopen($yourfile, 'rb');

    if (strstr($_SERVER['HTTP_USER_AGENT'], "MSIE"))
    header('Content-Type: "application/octet-stream"');
    header('Content-Disposition: attachment; filename="yourname.file"');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header("Content-Transfer-Encoding: binary");
    header('Pragma: public');
    header("Content-Length: ".filesize($yourfile));
    header('Content-Type: "application/octet-stream"');
    header('Content-Disposition: attachment; filename="yourname.file"');
    header("Content-Transfer-Encoding: binary");
    header('Expires: 0');
    header('Pragma: no-cache');
    header("Content-Length: ".filesize($yourfile));


How to bind 'touchstart' and 'click' events but not respond to both?

Update: Check out the jQuery Pointer Events Polyfill project which allows you to bind to "pointer" events instead of choosing between mouse & touch.

Bind to both, but make a flag so the function only fires once per 100ms or so.

var flag = false;
$thing.bind('touchstart click', function(){
  if (!flag) {
    flag = true;
    setTimeout(function(){ flag = false; }, 100);
    // do something

  return false

What is the difference between DTR/DSR and RTS/CTS flow control?

The difference between them is that they use different pins. Seriously, that's it. The reason they both exist is that RTS/CTS wasn't supposed to ever be a flow control mechanism, originally; it was for half-duplex modems to coordinate who was sending and who was receiving. RTS and CTS got misused for flow control so often that it became standard.

Using ffmpeg to encode a high quality video

A couple of things:

  • You need to set the video bitrate. I have never used minrate and maxrate so I don't know how exactly they work, but by setting the bitrate using the -b switch, I am able to get high quality video. You need to come up with a bitrate that offers a good tradeoff between compression and video quality. You may have to experiment with this because it all depends on the frame size, frame rate and the amount of motion in the content of your video. Keep in mind that DVD tends to be around 4-5 Mbit/s on average for 720x480, so I usually start from there and decide whether I need more or less and then just experiment. For example, you could add -b 5000k to the command line to get more or less DVD video bitrate.

  • You need to specify a video codec. If you don't, ffmpeg will default to MPEG-1 which is quite old and does not provide near the amount of compression as MPEG-4 or H.264. If your ffmpeg version is built with libx264 support, you can specify -vcodec libx264 as part of the command line. Otherwise -vcodec mpeg4 will also do a better job than MPEG-1, but not as well as x264.

  • There are a lot of other advanced options that will help you squeeze out the best quality at the lowest bitrates. Take a look here for some examples.

How do you clear the console screen in C?

A workaround tested on Windows(cmd.exe), Linux(Bash and zsh) and OS X(zsh):

#include <stdlib.h>

void clrscr()

How can I get color-int from color resource?

Found an easier way that works as well:


Using Composer's Autoload

There also other ways to use the composer autoload features. Ways that can be useful to load packages without namespaces or packages that come with a custom autoload function.

For example if you want to include a single file that contains an autoload function as well you can use the "files" directive as follows:

"autoload": {
    "psr-0": {
        "": "src/",
        "SymfonyStandard": "app/"
    "files": ["vendor/wordnik/wordnik-php/wordnik/Swagger.php"]

And inside the Swagger.php file we got:

function swagger_autoloader($className) {
    $currentDir = dirname(__FILE__);
    if (file_exists($currentDir . '/' . $className . '.php')) {
        include $currentDir . '/' . $className . '.php';
    } elseif (file_exists($currentDir . '/models/' . $className . '.php')) {
        include $currentDir . '/models/' . $className . '.php';

Otherwise you may want to use a classmap reference:

    "autoload": {
        "classmap": ["src/", "lib/", "Something.php"]

Note: during your tests remember to launch the composer dump-autoload command or you won't see any change!

./composer.phar dump-autoload

Happy autoloading =)

How to get the first word of a sentence in PHP?

There is a string function (strtok) which can be used to split a string into smaller strings (tokens) based on some separator(s). For the purposes of this thread, the first word (defined as anything before the first space character) of Test me more can be obtained by tokenizing the string on the space character.

$value = "Test me more";
echo strtok($value, " "); // Test

For more details and examples, see the strtok PHP manual page.

How to convert xml into array in php?

Converting an XML string ($buffer) into a simplified array ignoring attributes and grouping child-elements with the same names:

function XML2Array(SimpleXMLElement $parent)
    $array = array();

    foreach ($parent as $name => $element) {
        ($node = & $array[$name])
            && (1 === count($node) ? $node = array($node) : 1)
            && $node = & $node[];

        $node = $element->count() ? XML2Array($element) : trim($element);

    return $array;

$xml   = simplexml_load_string($buffer);
$array = XML2Array($xml);
$array = array($xml->getName() => $array);


    [aaaa] => Array
            [bbb] => Array
                    [cccc] => Array
                            [dddd] => 
                            [eeee] => 




If you also want to have the attributes, they are available via JSON encoding/decoding of SimpleXMLElement. This is often the most easy quick'n'dirty solution:

$xml   = simplexml_load_string($buffer);
$array = json_decode(json_encode((array) $xml), true);
$array = array($xml->getName() => $array);


    [aaaa] => Array
            [@attributes] => Array
                    [Version] => 1.0

            [bbb] => Array
                    [cccc] => Array
                            [dddd] => Array
                                    [@attributes] => Array
                                            [Id] => id:pass


                            [eeee] => Array
                                    [@attributes] => Array
                                            [name] => hearaman
                                            [age] => 24






Take note that all these methods only work in the namespace of the XML document.

Remove specific rows from a data frame

 X <- data.frame(Variable1=c(11,14,12,15),Variable2=c(2,3,1,4))
> X
  Variable1 Variable2
1        11         2
2        14         3
3        12         1
4        15         4
> X[X$Variable1!=11 & X$Variable1!=12, ]
  Variable1 Variable2
2        14         3
4        15         4
> X[ ! X$Variable1 %in% c(11,12), ]
  Variable1 Variable2
2        14         3
4        15         4

You can functionalize this however you like.

Extracting date from a string in Python

Using Pygrok, you can define abstracted extensions to the Regular Expression syntax.

The custom patterns can be included in your regex in the format %{PATTERN_NAME}.

You can also create a label for that pattern, by separating with a colon: %s{PATTERN_NAME:matched_string}. If the pattern matches, the value will be returned as part of the resulting dictionary (e.g. result.get('matched_string'))

For example:

from pygrok import Grok

input_string = 'monkey 2010-07-10 love banana'
date_pattern = '%{YEAR:year}-%{MONTHNUM:month}-%{MONTHDAY:day}'

grok = Grok(date_pattern)

The resulting value will be a dictionary:

{'month': '07', 'day': '10', 'year': '2010'}

If the date_pattern does not exist in the input_string, the return value will be None. By contrast, if your pattern does not have any labels, it will return an empty dictionary {}


read input separated by whitespace(s) or newline...?

Use 'q' as the the optional argument to getline.

#include <iostream>
#include <sstream>

int main() {
    std::string numbers_str;
    getline( std::cin, numbers_str, 'q' );

    int number;
    for ( std::istringstream numbers_iss( numbers_str );
          numbers_iss >> number; ) {
        std::cout << number << ' ';

Truncate number to two decimal places without rounding

My version for positive numbers:

function toFixed_norounding(n,p)
    var result = n.toFixed(p);
    return result <= n ? result: (result - Math.pow(0.1,p)).toFixed(p);

Fast, pretty, obvious. (version for positive numbers)

C# HttpClient 4.5 multipart/form-data upload

This is an example of how to post string and file stream with HTTPClient using MultipartFormDataContent. The Content-Disposition and Content-Type need to be specified for each HTTPContent:

Here's my example. Hope it helps:

private static void Upload()
    using (var client = new HttpClient())
        client.DefaultRequestHeaders.Add("User-Agent", "CBS Brightcove API Service");

        using (var content = new MultipartFormDataContent())
            var path = @"C:\B2BAssetRoot\files\596086\596086.1.mp4";

            string assetName = Path.GetFileName(path);

            var request = new HTTPBrightCoveRequest()
                    Method = "create_video",
                    Parameters = new Params()
                            CreateMultipleRenditions = "true",
                            EncodeTo = EncodeTo.Mp4.ToString().ToUpper(),
                            Token = "x8sLalfXacgn-4CzhTBm7uaCxVAPjvKqTf1oXpwLVYYoCkejZUsYtg..",
                            Video = new Video()
                                    Name = assetName,
                                    ReferenceId = Guid.NewGuid().ToString(),
                                    ShortDescription = assetName

            //Content-Disposition: form-data; name="json"
            var stringContent = new StringContent(JsonConvert.SerializeObject(request));
            stringContent.Headers.Add("Content-Disposition", "form-data; name=\"json\"");
            content.Add(stringContent, "json");

            FileStream fs = File.OpenRead(path);

            var streamContent = new StreamContent(fs);
            streamContent.Headers.Add("Content-Type", "application/octet-stream");
            //Content-Disposition: form-data; name="file"; filename="C:\B2BAssetRoot\files\596090\596090.1.mp4";
            streamContent.Headers.Add("Content-Disposition", "form-data; name=\"file\"; filename=\"" + Path.GetFileName(path) + "\"");
            content.Add(streamContent, "file", Path.GetFileName(path));

            //content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");

            Task<HttpResponseMessage> message = client.PostAsync("", content);

            var input = message.Result.Content.ReadAsStringAsync();

makefile:4: *** missing separator. Stop

On VS Code, just click the "Space: 4" on the downright corner and change it to tab when editing your Makefile.

Expand a random range from 1–5 to 1–7

The premise behind Adam Rosenfield's correct answer is:

  • x = 5^n (in his case: n=2)
  • manipulate n rand5 calls to get a number y within range [1, x]
  • z = ((int)(x / 7)) * 7
  • if y > z, try again. else return y % 7 + 1

When n equals 2, you have 4 throw-away possibilities: y = {22, 23, 24, 25}. If you use n equals 6, you only have 1 throw-away: y = {15625}.

5^6 = 15625
7 * 2232 = 15624

You call rand5 more times. However, you have a much lower chance of getting a throw-away value (or an infinite loop). If there is a way to get no possible throw-away value for y, I haven't found it yet.

python - find index position in list based of partial string

spell_list = ["Tuesday", "Wednesday", "February", "November", "Annual", "Calendar", "Solstice"]


Click through div to underlying elements

Allowing the user to click through a div to the underlying element depends on the browser. All modern browsers, including Firefox, Chrome, Safari, and Opera, understand pointer-events:none.

For IE, it depends on the background. If the background is transparent, clickthrough works without you needing to do anything. On the other hand, for something like background:white; opacity:0; filter:Alpha(opacity=0);, IE needs manual event forwarding.

See a JSFiddle test and CanIUse pointer events.

How to capture and save an image using custom camera in Android?

 showbookimage.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {

                // create intent with ACTION_IMAGE_CAPTURE action
                Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
 Here REQUEST_IMAGE is the unique integer value you can pass it any integer
                // start camera activity
                startActivityForResult(intent, TAKE_PICTURE);



then u can now give the image a file name as follows and then convert it into bitmap and later on to file

 private void createImageFile(Bitmap bitmap) throws IOException {
        // Create an image file name
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 40, bytes);
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = Environment.getExternalStoragePublicDirectory(
        File image = File.createTempFile(
                imageFileName,  /* prefix */
                ".jpg",         /* suffix */
                storageDir      /* directory */
        FileOutputStream stream = new FileOutputStream(image);
        // Save a file: path for use with ACTION_VIEW intents
        mCurrentPhotoPath = "file:" + image.getAbsolutePath();
        fileUri = image.getAbsolutePath();
    public void onActivityResult(int requestCode, int resultCode, Intent intent) {

        if (requestCode == TAKE_PICTURE && resultCode== Activity.RESULT_OK && intent != null){
            // get bundle
            Bundle extras = intent.getExtras();
            // get
            bitMap = (Bitmap) extras.get("data");
//            showbookimage.setImageBitmap(bitMap);
            try {
            } catch (IOException e) {


use picasso for images to display rather fast

Extract text from a string

The following regex extract anything between the parenthesis:

PS> $prog = [regex]::match($s,'\(([^\)]+)\)').Groups[1].Value
PS> $prog

Explanation (created with RegexBuddy)

Match the character '(' literally «\(»
Match the regular expression below and capture its match into backreference number 1 «([^\)]+)»
   Match any character that is NOT a ) character «[^\)]+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character ')' literally «\)»

Check these links:

How can I mimic the bottom sheet from the Maps app?

I recently created a component called SwipeableView as subclass of UIView, written in Swift 5.1 . It support all 4 direction, has several customisation options and can animate and interpolate different attributes and items ( such as layout constraints, background/tint color, affine transform, alpha channel and view center, all of them demoed with the respective show case ). It also supports the swiping coordination with the inner scroll view if set or auto detected. Should be pretty easy and straightforward to be used ( I hope )

Link at

proof of concept:

enter image description here

Hope it helps

JavaScript validation for empty input field

<script type="text/javascript">_x000D_
  function validateForm() {_x000D_
    var a = document.forms["Form"]["answer_a"].value;_x000D_
    var b = document.forms["Form"]["answer_b"].value;_x000D_
    var c = document.forms["Form"]["answer_c"].value;_x000D_
    var d = document.forms["Form"]["answer_d"].value;_x000D_
    if (a == null || a == "", b == null || b == "", c == null || c == "", d == null || d == "") {_x000D_
      alert("Please Fill All Required Field");_x000D_
      return false;_x000D_
<form method="post" name="Form" onsubmit="return validateForm()" action="">_x000D_
  <textarea cols="30" rows="2" name="answer_a" id="a"></textarea>_x000D_
  <textarea cols="30" rows="2" name="answer_b" id="b"></textarea>_x000D_
  <textarea cols="30" rows="2" name="answer_c" id="c"></textarea>_x000D_
  <textarea cols="30" rows="2" name="answer_d" id="d"></textarea>_x000D_

start MySQL server from command line on Mac OS Lion

111028 16:57:43 [ERROR] Fatal error: Please read "Security" section of the manual to find out how to run mysqld as root!

Have you set a root password for your mysql installation? This is different to your sudo root password. Try /usr/local/mysql/bin/mysql_secure_installation

SQL Server: SELECT only the rows with MAX(DATE)

For MySql you can do something like the following:

select OrderNO, PartCode, Quantity from table a
join (select ID, MAX(DateEntered) from table group by OrderNO) b on a.ID = b.ID

How to display pandas DataFrame of floats using a format string for columns?

import pandas as pd
pd.options.display.float_format = '${:,.2f}'.format
df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],


foo  $123.46
bar  $234.57
baz  $345.68
quux $456.79

but this only works if you want every float to be formatted with a dollar sign.

Otherwise, if you want dollar formatting for some floats only, then I think you'll have to pre-modify the dataframe (converting those floats to strings):

import pandas as pd
df = pd.DataFrame([123.4567, 234.5678, 345.6789, 456.7890],
df['foo'] = df['cost']
df['cost'] = df['cost'].map('${:,.2f}'.format)


         cost       foo
foo   $123.46  123.4567
bar   $234.57  234.5678
baz   $345.68  345.6789
quux  $456.79  456.7890

How to create local notifications?

    NSMutableArray *allControllers = [[NSMutableArray alloc] initWithArray:self.navigationController.viewControllers];
    NSArray *allControllersCopy = [allControllers copy];
    if ([[allControllersCopy lastObject] isKindOfClass: [kundanViewController class]]) 
        [[NSNotificationCenter defaultCenter]postNotificationName:@"kundanViewControllerHide"object:nil userInfo:nil];
        [[NSUserDefaults standardUserDefaults] setInteger:4 forKey:@"selected"];
        [self performSegueWithIdentifier:@"kundansegue" sender:self];

[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(ApparelsViewControllerHide) name:@"ApparelsViewControllerHide" object:nil];

Random color generator

Here is another take on this problem.

My goal was to create vibrant and distinct colors. To ensure the colors are distinct I avoid using a random generator and select "evenly spaced" colors from the rainbow.

This is perfect for creating pop-out markers in Google Maps that have optimal "uniqueness" (that is, no two markers will have similar colors).

function rainbow(numOfSteps, step) {
    // This function generates vibrant, "evenly spaced" colours (i.e. no clustering). This is ideal for creating easily distinguishable vibrant markers in Google Maps and other apps.
    // Adam Cole, 2011-Sept-14
    // HSV to RBG adapted from:
    var r, g, b;
    var h = step / numOfSteps;
    var i = ~~(h * 6);
    var f = h * 6 - i;
    var q = 1 - f;
    switch(i % 6){
        case 0: r = 1; g = f; b = 0; break;
        case 1: r = q; g = 1; b = 0; break;
        case 2: r = 0; g = 1; b = f; break;
        case 3: r = 0; g = q; b = 1; break;
        case 4: r = f; g = 0; b = 1; break;
        case 5: r = 1; g = 0; b = q; break;
    var c = "#" + ("00" + (~ ~(r * 255)).toString(16)).slice(-2) + ("00" + (~ ~(g * 255)).toString(16)).slice(-2) + ("00" + (~ ~(b * 255)).toString(16)).slice(-2);
    return (c);

If you wish to see what this looks like in action see Simple JavaScript Rainbow Color Generator for Google Map Markers.

How to launch an EXE from Web page (

if the applications are C#, you can use ClickOnce deployment, which is a good option if you can't guarentee the user will have the app, however you'll have to re-build the apps with deployment options and grab some boilerplate code from each project.

You can also use Javascript.

Or you can register an application to handle a new web protocol you can define. This could also be an "app selection" protocol, so each time an app is clicked it would link to a page on your new protocol, all handling of this protocol is then passed to your "selection app" which uses arguments to find and launch an app on the clients PC.


Convert array of strings into a string in Java

Try the Arrays.toString overloaded methods.

Or else, try this below generic implementation:

public static void main(String... args) throws Exception {

    String[] array = {"ABC", "XYZ", "PQR"};

    System.out.println(new Test().join(array, ", "));

public <T> String join(T[] array, String cement) {
    StringBuilder builder = new StringBuilder();

    if(array == null || array.length == 0) {
        return null;

    for (T t : array) {

    builder.delete(builder.length() - cement.length(), builder.length());

    return builder.toString();

jQuery table sort

Another approach to sort HTML table. (based on W3.JS HTML Sort)

/* Facility Name */_x000D_
$('#bioTable th:eq(0)').addClass("control-label pointer");_x000D_
/* Phone # */_x000D_
$('#bioTable th:eq(1)').addClass("not-allowed");_x000D_
/* City */_x000D_
$('#bioTable th:eq(2)').addClass("control-label pointer");_x000D_
/* Specialty */_x000D_
$('#bioTable th:eq(3)').addClass("not-allowed");_x000D_
var collection = [{_x000D_
  "FacilityName": "MinION",_x000D_
  "Phone": "999-8888",_x000D_
  "City": "France",_x000D_
  "Specialty": "Genetic Prediction"_x000D_
}, {_x000D_
  "FacilityName": "GridION X5",_x000D_
  "Phone": "999-8812",_x000D_
  "City": "Singapore",_x000D_
  "Specialty": "DNA Assembly"_x000D_
}, {_x000D_
  "FacilityName": "PromethION",_x000D_
  "Phone": "929-8888",_x000D_
  "City": "San Francisco",_x000D_
  "Specialty": "DNA Testing"_x000D_
}, {_x000D_
  "FacilityName": "iSeq 100 System",_x000D_
  "Phone": "999-8008",_x000D_
  "City": "Christchurch",_x000D_
  "Specialty": "gDNA-mRNA sequencing"_x000D_
$tbody = $("#bioTable").append('<tbody></tbody>');_x000D_
for (var i = 0; i < collection.length; i++) {_x000D_
  $tbody = $tbody.append('<tr class="item"><td>' + collection[i]["FacilityName"] + '</td><td>' + collection[i]["Phone"] + '</td><td>' + collection[i]["City"] + '</td><td>' + collection[i]["Specialty"] + '</td></tr>');_x000D_
.control-label:after {_x000D_
  content: "*";_x000D_
  color: red;_x000D_
.pointer {_x000D_
  cursor: pointer;_x000D_
.not-allowed {_x000D_
  cursor: not-allowed;_x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<link href="" rel="stylesheet" />_x000D_
<p>Click the <strong>table headers</strong> to sort the table accordingly:</p>_x000D_
<table id="bioTable" class="w3-table-all">_x000D_
      <th onclick="w3.sortHTML('#bioTable', '.item', 'td:nth-child(1)')">Facility Name</th>_x000D_
      <th>Phone #</th>_x000D_
      <th onclick="w3.sortHTML('#bioTable', '.item', 'td:nth-child(3)')">City</th>_x000D_

How can I convert byte size into a human-readable format in Java?

private String bytesIntoHumanReadable(long bytes) {
    long kilobyte = 1024;
    long megabyte = kilobyte * 1024;
    long gigabyte = megabyte * 1024;
    long terabyte = gigabyte * 1024;

    if ((bytes >= 0) && (bytes < kilobyte)) {
        return bytes + " B";

    } else if ((bytes >= kilobyte) && (bytes < megabyte)) {
        return (bytes / kilobyte) + " KB";

    } else if ((bytes >= megabyte) && (bytes < gigabyte)) {
        return (bytes / megabyte) + " MB";

    } else if ((bytes >= gigabyte) && (bytes < terabyte)) {
        return (bytes / gigabyte) + " GB";

    } else if (bytes >= terabyte) {
        return (bytes / terabyte) + " TB";

    } else {
        return bytes + " Bytes";

Operation is not valid due to the current state of the object, when I select a dropdown list


Issue happens because Microsoft Security Update MS11-100 limits number of keys in Forms collection during HTTP POST request. To alleviate this problem you need to increase that number.

This can be done in your application Web.Config in the <appSettings> section (create the section directly under <configuration> if it doesn’t exist). Add 2 lines similar to the lines below to the section:

<add key="aspnet:MaxHttpCollectionKeys" value="2000" />
<add key="aspnet:MaxJsonDeserializerMembers" value="2000" />

The above example set the limit to 2000 keys. This will lift the limitation and the error should go away.

How do you find the first key in a dictionary?

Update: as of Python 3.7, insertion order is maintained, so you don't need an OrderedDict here. You can use the below approaches with a normal dict

Changed in version 3.7: Dictionary order is guaranteed to be insertion order. This behavior was an implementation detail of CPython from 3.6.


Python 3.6 and earlier*

If you are talking about a regular dict, then the "first key" doesn't mean anything. The keys are not ordered in any way you can depend on. If you iterate over your dict you will likely not get "banana" as the first thing you see.

If you need to keep things in order, then you have to use an OrderedDict and not just a plain dictionary.

import collections
prices  = collections.OrderedDict([
        ("banana", 4),
        ("apple", 2),
        ("orange", 1.5),
        ("pear", 3),

If you then wanted to see all the keys in order you could do so by iterating through it

for k in prices:

You could, alternatively put all of the keys into a list and then work with that

ks = list(prices)
print(ks[0]) # will print "banana"

A faster way to get the first element without creating a list would be to call next on the iterator. This doesn't generalize nicely when trying to get the nth element though

>>> next(iter(prices))

* CPython had guaranteed insertion order as an implementation detail in 3.6.

Get a UTC timestamp

As wizzard pointed out, the correct method is,

new Date().getTime();

or under Javascript 1.5, just;

From the documentation,

The value returned by the getTime method is the number of milliseconds since 1 January 1970 00:00:00 UTC.

If you wanted to make a time stamp without milliseconds you can use,

Math.floor( / 1000);

I wanted to make this an answer so the correct method is more visible.

You can compare ExpExc's and Narendra Yadala's results to the method above at, and verify with or by running date +%s on a Unix terminal.

How can I flush GPU memory using CUDA (physical reset is unavailable)

One can also use nvtop, which gives an interface very similar to htop, but showing your GPU(s) usage instead, with a nice graph. You can also kill processes directly from here.

Here is a link to its Github :

NVTOP interface

How to use variables in a command in sed?


sed "s|\$ROOT|${HOME}|"


  • Use double quotes so that the shell would expand variables.
  • Use a separator different than / since the replacement contains /
  • Escape the $ in the pattern since you don't want to expand it.

EDIT: In order to replace all occurrences of $ROOT, say

sed "s|\$ROOT|${HOME}|g"

Using a string variable as a variable name

You will be much happier using a dictionary instead:

my_data = {}
foo = "hello"
my_data[foo] = "goodbye"
assert my_data["hello"] == "goodbye"

How to resize a custom view programmatically?

I used this way to increase width of custom view Runnable() {
                            public void run() {
                                View view_instance = customDrawingView;
                                android.view.ViewGroup.LayoutParams params = view_instance
                                int newLayoutWidth = customDrawingView
                                        + customDrawingView.getWidth();
                                params.width = newLayoutWidth;
                                screenWidthBackup = params.width;

Matplotlib scatterplot; colour as a function of a third variable

Sometimes you may need to plot color precisely based on the x-value case. For example, you may have a dataframe with 3 types of variables and some data points. And you want to do following,

  • Plot points corresponding to Physical variable 'A' in RED.
  • Plot points corresponding to Physical variable 'B' in BLUE.
  • Plot points corresponding to Physical variable 'C' in GREEN.

In this case, you may have to write to short function to map the x-values to corresponding color names as a list and then pass on that list to the plt.scatter command.


# Function to map the colors as a list from the input list of x variables
def pltcolor(lst):
    for l in lst:
        if l=='A':
        elif l=='B':
    return cols
# Create the colors list using the function above

plt.scatter(x=x,y=y,s=500,c=cols) #Pass on the list created by the function here

Coloring scatter plot as a function of x variable

return, return None, and no return at all?

Yes, they are all the same.

We can review the interpreted machine code to confirm that that they're all doing the exact same thing.

import dis

def f1():
  print "Hello World"
  return None

def f2():
  print "Hello World"

def f3():
  print "Hello World"

    4   0 LOAD_CONST    1 ('Hello World')
        3 PRINT_ITEM

    5   5 LOAD_CONST    0 (None)
        8 RETURN_VALUE

    9   0 LOAD_CONST    1 ('Hello World')
        3 PRINT_ITEM

    10  5 LOAD_CONST    0 (None)
        8 RETURN_VALUE

    14  0 LOAD_CONST    1 ('Hello World')
        3 PRINT_ITEM
        4 PRINT_NEWLINE            
        5 LOAD_CONST    0 (None)
        8 RETURN_VALUE      

filename.whl is not supported wheel on this platform

In my case it had to do with not having installed previously the GDAL core. For a guide on how to install the GDAL and Basemap libraries go to:

C++ cout hex values?

I understand this isn't what OP asked for, but I still think it is worth to point out how to do it with printf. I almost always prefer using it over std::cout (even with no previous C background).

printf("%.2X", a);

'2' defines the precision, 'X' or 'x' defines case.

Is there a splice method for strings?

Here's a nice little Curry which lends better readability (IMHO):

The second function's signature is identical to the Array.prototype.splice method.

function mutate(s) {
    return function splice() {
        var a = s.split('');
        Array.prototype.splice.apply(a, arguments);
        return a.join('');

mutate('101')(1, 1, '1');

I know there's already an accepted answer, but hope this is useful.

How do I make an asynchronous GET request in PHP?

This is how to make Marquis' answer work with both POST and GET requests:

  // $type must equal 'GET' or 'POST'
  function curl_request_async($url, $params, $type='POST')
      foreach ($params as $key => &$val) {
        if (is_array($val)) $val = implode(',', $val);
        $post_params[] = $key.'='.urlencode($val);
      $post_string = implode('&', $post_params);


      $fp = fsockopen($parts['host'],
          $errno, $errstr, 30);

      // Data goes in the path for a GET request
      if('GET' == $type) $parts['path'] .= '?'.$post_string;

      $out = "$type ".$parts['path']." HTTP/1.1\r\n";
      $out.= "Host: ".$parts['host']."\r\n";
      $out.= "Content-Type: application/x-www-form-urlencoded\r\n";
      $out.= "Content-Length: ".strlen($post_string)."\r\n";
      $out.= "Connection: Close\r\n\r\n";
      // Data goes in the request body for a POST request
      if ('POST' == $type && isset($post_string)) $out.= $post_string;

      fwrite($fp, $out);

Rails params explained?

As others have pointed out, params values can come from the query string of a GET request, or the form data of a POST request, but there's also a third place they can come from: The path of the URL.

As you might know, Rails uses something called routes to direct requests to their corresponding controller actions. These routes may contain segments that are extracted from the URL and put into params. For example, if you have a route like this:

match 'products/:id', ...

Then a request to a URL like will set params[:id] to 42.

Class constructor type in typescript?

Solution from typescript interfaces reference:

interface ClockConstructor {
    new (hour: number, minute: number): ClockInterface;
interface ClockInterface {

function createClock(ctor: ClockConstructor, hour: number, minute: number): ClockInterface {
    return new ctor(hour, minute);

class DigitalClock implements ClockInterface {
    constructor(h: number, m: number) { }
    tick() {
        console.log("beep beep");
class AnalogClock implements ClockInterface {
    constructor(h: number, m: number) { }
    tick() {
        console.log("tick tock");

let digital = createClock(DigitalClock, 12, 17);
let analog = createClock(AnalogClock, 7, 32);

So the previous example becomes:

interface AnimalConstructor {
    new (): Animal;

class Animal {
    constructor() {

class Penguin extends Animal {
    constructor() {

class Lion extends Animal {
    constructor() {

class Zoo {
    AnimalClass: AnimalConstructor // AnimalClass can be 'Lion' or 'Penguin'

    constructor(AnimalClass: AnimalConstructor) {
        this.AnimalClass = AnimalClass
        let Hector = new AnimalClass();

How can I save a base64-encoded image to disk?

I think you are converting the data a bit more than you need to. Once you create the buffer with the proper encoding, you just need to write the buffer to the file.

var base64Data = req.rawBody.replace(/^data:image\/png;base64,/, "");

require("fs").writeFile("out.png", base64Data, 'base64', function(err) {

new Buffer(..., 'base64') will convert the input string to a Buffer, which is just an array of bytes, by interpreting the input as a base64 encoded string. Then you can just write that byte array to the file.


As mentioned in the comments, req.rawBody is no longer a thing. If you are using express/connect then you should use the bodyParser() middleware and use req.body, and if you are doing this using standard Node then you need to aggregate the incoming data event Buffer objects and do this image data parsing in the end callback.

How to change SmartGit's licensing option after 30 days of commercial use on ubuntu?


cd ~/Library/Preferences/SmartGit/
sed -i '' '/listx/d' ./*/preferences.yml
rm */license

Windows portable path to preferences.yml:


Plot multiple columns on the same graph in R

To select columns to plot, I added 2 lines to Vincent Zoonekynd's answer:

#convert to tall/long format(from wide format)
col_plot = c("A","B")
dlong <- melt(d[,c("Xax", col_plot)], id.vars="Xax")  

#"value" and "variable" are default output column names of melt()
ggplot(dlong, aes(Xax,value, col=variable)) +
  geom_point() + 

Google "tidy data" to know more about tall(or long)/wide format.

Is it possible to run a .NET 4.5 app on XP?

I hesitate to post this answer, it is actually technically possible but it doesn't work that well in practice. The version numbers of the CLR and the core framework assemblies were not changed in 4.5. You still target v4.0.30319 of the CLR and the framework assembly version numbers are still The only thing that's distinctive about the assembly manifest when you look at it with a disassembler like ildasm.exe is the presence of a [TargetFramework] attribute that says that 4.5 is needed, that would have to be altered. Not actually that easy, it is emitted by the compiler.

The biggest difference is not that visible, Microsoft made a long-overdue change in the executable header of the assemblies. Which specifies what version of Windows the executable is compatible with. XP belongs to a previous generation of Windows, started with Windows 2000. Their major version number is 5. Vista was the start of the current generation, major version number 6.

.NET compilers have always specified the minimum version number to be 4.00, the version of Windows NT and Windows 9x. You can see this by running dumpbin.exe /headers on the assembly. Sample output looks like this:

             10B magic # (PE32)
            4.00 operating system version
            0.00 image version
            4.00 subsystem version              // <=== here!!
               0 Win32 version

What's new in .NET 4.5 is that the compilers change that subsystem version to 6.00. A change that was over-due in large part because Windows pays attention to that number, beyond just checking if it is small enough. It also turns on appcompat features since it assumes that the program was written to work on old versions of Windows. These features cause trouble, particularly the way Windows lies about the size of a window in Aero is troublesome. It stops lying about the fat borders of an Aero window when it can see that the program was designed to run on a Windows version that has Aero.

You can alter that version number and set it back to 4.00 by running Editbin.exe on your assemblies with the /subsystem option. This answer shows a sample postbuild event.

That's however about where the good news ends, a significant problem is that .NET 4.5 isn't very compatible with .NET 4.0. By far the biggest hang-up is that classes were moved from one assembly to another. Most notably, that happened for the [Extension] attribute. Previously in System.Core.dll, it got moved to Mscorlib.dll in .NET 4.5. That's a kaboom on XP if you declare your own extension methods, your program says to look in Mscorlib for the attribute, enabled by a [TypeForwardedTo] attribute in the .NET 4.5 version of the System.Core reference assembly. But it isn't there when you run your program on .NET 4.0

And of course there's nothing that helps you stop using classes and methods that are only available on .NET 4.5. When you do, your program will fail with a TypeLoadException or MissingMethodException when run on 4.0

Just target 4.0 and all of these problems disappear. Or break that logjam and stop supporting XP, a business decision that programmers cannot often make but can certainly encourage by pointing out the hassles that it is causing. There is of course a non-zero cost to having to support ancient operating systems, just the testing effort is substantial. A cost that isn't often recognized by management, Windows compatibility is legendary, unless it is pointed out to them. Forward that cost to the client and they tend to make the right decision a lot quicker :) But we can't help you with that.

How can I replace the deprecated set_magic_quotes_runtime in php?

add these code into the top of your script to solve problem

ini_set('magic_quotes_runtime', 0);

Difference between using gradlew and gradle

The difference lies in the fact that ./gradlew indicates you are using a gradle wrapper. The wrapper is generally part of a project and it facilitates installation of gradle. If you were using gradle without the wrapper you would have to manually install it - for example, on a mac brew install gradle and then invoke gradle using the gradle command. In both cases you are using gradle, but the former is more convenient and ensures version consistency across different machines.

Each Wrapper is tied to a specific version of Gradle, so when you first run one of the commands above for a given Gradle version, it will download the corresponding Gradle distribution and use it to execute the build.

Not only does this mean that you don’t have to manually install Gradle yourself, but you are also sure to use the version of Gradle that the build is designed for. This makes your historical builds more reliable

Read more here -

Also, Udacity has a neat, high level video explaining the concept of the gradle wrapper -

How do I do a case-insensitive string comparison?

def insenStringCompare(s1, s2):
    """ Method that takes two strings and returns True or False, based
        on if they are equal, regardless of case."""
        return s1.lower() == s2.lower()
    except AttributeError:
        print "Please only pass strings into this method."
        print "You passed a %s and %s" % (s1.__class__, s2.__class__)

Difference between 2 dates in SQLite

In my case, I have to calculate the difference in minutes and julianday() does not give an accurate value. Instead, I use strftime():

SELECT (strftime('%s', [UserEnd]) - strftime('%s', [UserStart])) / 60

Both dates are converted to unixtime (seconds), then subtracted to get value in seconds between the two dates. Next, divide it by 60.

How to specify table's height such that a vertical scroll bar appears?

This CSS also shows a fixed height HTML table. It sets the height of the HTML tbody to 400 pixels and the HTML tbody scrolls when the it is larger, retaining the HTML thead as a non-scrolling element.

In addition, each th cell in the heading and each td cell the body should be styled for the desired fixed width.

#the-table {
  display: block;
  background: white; /* optional */

#the-table thead {
  text-align: left; /* optional */

#the-table tbody {
  display: block;
  max-height: 400px;
  overflow-y: scroll;

How to select ALL children (in any level) from a parent in jQuery?

It seems that the original test case is wrong.

I can confirm that the selector #my_parent_element * works with unbind().

Let's take the following html as an example:

<div id="#my_parent_element">
  <div class="div1">
    <div class="div2">hello</div>
    <div class="div3">my</div>
  <div class="div4">name</div>
  <div class="div5">
    <div class="div6">is</div>
    <div class="div7">
      <div class="div8">marco</div>
      <div class="div9">(try and click on any word)!</div>
<button class="unbind">Now, click me and try again</button>

And the jquery bit:

$('.div1,.div2,.div3,.div4,.div5,.div6,.div7,.div8,.div9').click(function() {
$('button.unbind').click(function() {
  $('#my_parent_element *').unbind('click');

You can try it here:

how to delete the content of text file without deleting itself

Just print an empty string into the file:

PrintWriter writer = new PrintWriter(file);

forEach() in React JSX does not output any HTML

You need to pass an array of element to jsx. The problem is that forEach does not return anything (i.e it returns undefined). So it's better to use map because map returns an array:

class QuestionSet extends Component {
    <div className="container">
       {, i) => {     
           // Return the element. Also pass key     
           return (<Answer key={answer} answer={answer} />) 

export default QuestionSet;

How to set different colors in HTML in one statement?

Use the span tag


<span class="redText">My Name is:</span>&nbsp;<span class="blackText">Tintincute</span>

It's also a good idea to avoid inline styling. Use a custom CSS class instead.

How do I get list of all tables in a database using TSQL?

FROM sysobjects sobjects
WHERE sobjects.xtype = 'U'

Here is a list of other object types you can search for as well:

  • AF: Aggregate function (CLR)
  • C: CHECK constraint
  • D: Default or DEFAULT constraint
  • F: FOREIGN KEY constraint
  • L: Log
  • FN: Scalar function
  • FS: Assembly (CLR) scalar-function
  • FT: Assembly (CLR) table-valued function
  • IF: In-lined table-function
  • IT: Internal table
  • P: Stored procedure
  • PC: Assembly (CLR) stored-procedure
  • PK: PRIMARY KEY constraint (type is K)
  • RF: Replication filter stored procedure
  • S: System table
  • SN: Synonym
  • SQ: Service queue
  • TA: Assembly (CLR) DML trigger
  • TF: Table function
  • TR: SQL DML Trigger
  • TT: Table type
  • U: User table
  • UQ: UNIQUE constraint (type is K)
  • V: View
  • X: Extended stored procedure

How to check Spark Version

Addition to @Binary Nerd

If you are using Spark, use the following to get the Spark version:

spark-submit --version


Login to the Cloudera Manager and goto Hosts page then run inspect hosts in cluster

SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

In my case, everything was set up correctly, but my Docker infrastructure needed more RAM. I'm using Docker for Mac, where default RAM was around 1 GB, and as MySQL uses around 1.5Gb of RAM ( and probably was crashing ??? ), changing the Docker RAM utilization level to 3-4 Gb solved the issue.

Howto: Clean a mysql InnoDB storage engine?

The InnoDB engine does not store deleted data. As you insert and delete rows, unused space is left allocated within the InnoDB storage files. Over time, the overall space will not decrease, but over time the 'deleted and freed' space will be automatically reused by the DB server.

You can further tune and manage the space used by the engine through an manual re-org of the tables. To do this, dump the data in the affected tables using mysqldump, drop the tables, restart the mysql service, and then recreate the tables from the dump files.

Split string with string as delimiter

I recently discovered an interesting trick that allows to "Split String With String As Delimiter", so I couldn't resist the temptation to post it here as a new answer. Note that "obviously the question wasn't accurate. Firstly, both string1 and string2 can contain spaces. Secondly, both string1 and string2 can contain ampersands ('&')". This method correctly works with the new specifications (posted as a comment below Stephan's answer).

@echo off

set "str=string1&with spaces by string2&with spaces.txt"

set "string1=%str: by =" & set "string2=%"
set "string2=%string2:.txt=%"

echo "%string1%"
echo "%string2%"

For further details on the split method, see this post.

How to detect installed version of MS-Office?

Despite the fact that this question has been answered long time ago, I found some interesting facts to add that are related to the answers above.

As Dirk mentioned, there seems to be a weird fashion of version control from MS, starting from Office 365 / 2019. You cannot distinguish among the three(2016, 2019, O365), by seeing at the executable paths anymore. And just like he reputed himself, looking at the builds of the executable, as a mean of telling which is what, isn't quite effective either.

After some researching, I found a feasible solution. The solution lies under the registry subkey Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Licensing\LicensingNext.

So, my logic follows below:

Case 1: If the computer has the MSOffice 2016 installed, there is no subkeys under Licensing.

Case 2: if the computer has MSOffice 2019 installed, there is the name of the value (which is one of the Office Product ID). (e.g. Standard2019Volume)

Case 3: if the computer has Office365 installed, there is a value called o365bussinessretail(which is also a product ID) along with some other values.

The possible productIds are provided here.

To distinguish the three, I just opened the key and see if fails. If the open fails, its Office 2016. Then I enumerate LicensingNext and try to see if any name has a prefix o365, if it finds it then its O365. If it does not, then its Office 2019.

Frankly speaking, I did not have enough time to test the logic under varying environment. So please, note that.

Hope this will help whoever's interest.

Bootstrap 3 Slide in Menu / Navbar on Mobile

Bootstrap 4

Create a responsive navbar sidebar "drawer" in Bootstrap 4?
Bootstrap horizontal menu collapse to sidemenu

Bootstrap 3

I think what you're looking for is generally known as an "off-canvas" layout. Here is the standard off-canvas example from the official Bootstrap docs:

The "official" example uses a right-side sidebar the toggle off and on separately from the top navbar menu. I also found these off-canvas variations that slide in from the left and may be closer to what you're looking for..

Html/PHP - Form - Input as array

in addition: for those who have a empty POST variable, don't use this:


rather use this (as it is already here in this example):


iTunes Connect Screenshots Sizes for all iOS (iPhone/iPad/Apple Watch) devices

In Xcode 9, in addition to setting the Window Scale to 100% (?1) it is now necessary to also uncheck Optimize Rendering for Window Scale in the debug menu in order to get a screenshot of the proper resolution.

To take a screenshot of the proper size for use on the app store:

1.) Run app in simulator
2.) Set scale (?1)
3.) Uncheck Optimize Rendering for Window Scalein debug menu
4.) Take a Screenshot with ?S

enter image description here

How to use ConfigurationManager

Go to tools >> nuget >> console and type:

Install-Package System.Configuration.ConfigurationManager 

If you want a specific version:

Install-Package System.Configuration.ConfigurationManager -Version 4.5.0

Your ConfigurationManager dll will now be imported and the code will begin to work.

HTML/Javascript change div content

Assuming you're not using jQuery or some other library that makes this sort of thing easier for you, you can just use the element's innerHTML property.

document.getElementById("content").innerHTML = "whatever";

How do I concatenate two strings in C?

Concatenate Strings

Concatenating any two strings in C can be done in atleast 3 ways :-

1) By copying string 2 to the end of string 1

#include <stdio.h>
#include <string.h>
#define MAX 100
int main()
  char str1[MAX],str2[MAX];
  int i,j=0;
  printf("Input string 1: ");
  printf("\nInput string 2: ");
  for(i=strlen(str1);str2[j]!='\0';i++)  //Copying string 2 to the end of string 1
  printf("\nConcatenated string: ");
  return 0;

2) By copying string 1 and string 2 to string 3

#include <stdio.h>
#include <string.h>
#define MAX 100
int main()
  char str1[MAX],str2[MAX],str3[MAX];
  int i,j=0,count=0;
  printf("Input string 1: ");
  printf("\nInput string 2: ");
  for(i=0;str1[i]!='\0';i++)          //Copying string 1 to string 3
  for(i=count;str2[j]!='\0';i++)     //Copying string 2 to the end of string 3
  printf("\nConcatenated string : ");
  return 0;

3) By using strcat() function

#include <stdio.h>
#include <string.h>
#define MAX 100
int main()
  char str1[MAX],str2[MAX];
  printf("Input string 1: ");
  printf("\nInput string 2: ");
  strcat(str1,str2);                    //strcat() function
  printf("\nConcatenated string : ");
  return 0;

When I run `npm install`, it returns with `ERR! code EINTEGRITY` (npm 5.3.0)

Easy and fast fix for me was to npm install the specific package on which it said the sha is wrong. Say your package is called awesome-package.

My solution was:

npm i awesome-package

This updated my sha within the package-lock.json.

When to use Spring Security`s antMatcher()?

You need antMatcher for multiple HttpSecurity, see Spring Security Reference:

5.7 Multiple HttpSecurity

We can configure multiple HttpSecurity instances just as we can have multiple <http> blocks. The key is to extend the WebSecurityConfigurationAdapter multiple times. For example, the following is an example of having a different configuration for URL’s that start with /api/.

public class MultiHttpSecurityConfig {
  public void configureGlobal(AuthenticationManagerBuilder auth) { 1
              .withUser("admin").password("password").roles("USER", "ADMIN");

  @Order(1)                                                        2
  public static class ApiWebSecurityConfigurationAdapter extends WebSecurityConfigurerAdapter {
      protected void configure(HttpSecurity http) throws Exception {
              .antMatcher("/api/**")                               3

  @Configuration                                                   4
  public static class FormLoginWebSecurityConfigurerAdapter extends WebSecurityConfigurerAdapter {

      protected void configure(HttpSecurity http) throws Exception {

1 Configure Authentication as normal

2 Create an instance of WebSecurityConfigurerAdapter that contains @Order to specify which WebSecurityConfigurerAdapter should be considered first.

3 The http.antMatcher states that this HttpSecurity will only be applicable to URLs that start with /api/

4 Create another instance of WebSecurityConfigurerAdapter. If the URL does not start with /api/ this configuration will be used. This configuration is considered after ApiWebSecurityConfigurationAdapter since it has an @Order value after 1 (no @Order defaults to last).

In your case you need no antMatcher, because you have only one configuration. Your modified code:

        .somethingElse() // for /high_level_url_A/**
        .somethingElse() // for /high_level_url_B/**

number_format() with MySQL

You can use

SELECT round(123.4566,2)  -> 123.46

How can you use php in a javascript function

you use script in php..


        $num = 1;
        echo $num;

    echo '<input type="button"
           value="Click to increment"
           onclick="Inc()" />
        function Inc()
            $num = 2;
            echo $num;

        echo '}

android: changing option menu items programmatically

To disable certain items:

MenuItem item = menu.findItem(;

Is there a good jQuery Drag-and-drop file upload plugin?

If you're looking for one that doesn't rely on Flash then dropzonejs is a good shout. It supports multiple files and drag and drop.

How to get hostname from IP (Linux)?

In order to use nslookup, host or gethostbyname() then the target's name will need to be registered with DNS or statically defined in the hosts file on the machine running your program. Yes, you could connect to the target with SSH or some other application and query it directly, but for a generic solution you'll need some sort of DNS entry for it.

How can I get CMake to find my alternative Boost installation?

There is a generic method to give CMake directions about where to find libraries.

When looking for a library, CMake looks first in the following variables:


If you declare your Boost files in one of the environment variables, CMake will find it. Example:

export CMAKE_LIBRARY_PATH="/stuff/lib.boost.1.52/lib:$CMAKE_LIBRARY_PATH"
export CMAKE_INCLUDE_PATH="/stuff/lib.boost.1.52/include:$CMAKE_INCLUDE_PATH"

If it's too cumbersome, you can also use a nice installing tool I wrote that will do everything for you: C++ version manager

Difference between signed / unsigned char

Representation is the same, the meaning is different. e.g, 0xFF, it both represented as "FF". When it is treated as "char", it is negative number -1; but it is 255 as unsigned. When it comes to bit shifting, it is a big difference since the sign bit is not shifted. e.g, if you shift 255 right 1 bit, it will get 127; shifting "-1" right will be no effect.

Convert Python ElementTree to string

Non-Latin Answer Extension

Extension to @Stevoisiak's answer and dealing with non-Latin characters. Only one way will display the non-Latin characters to you. The one method is different on both Python 3 and Python 2.


xml = ElementTree.fromstring('<Person Name="???" />')
xml = ElementTree.Element("Person", Name="???")  # Read Note about Python 2

NOTE: In Python 2, when calling the toString(...) code, assigning xml with ElementTree.Element("Person", Name="???")will raise an error...

UnicodeDecodeError: 'ascii' codec can't decode byte 0xed in position 0: ordinal not in range(128)


# Python 3 (???): b'<Person Name="&#53356;&#47532;&#49828;" />'
# Python 3 (John): b'<Person Name="John" />'

# Python 2 (???): <Person Name="&#53356;&#47532;&#49828;" />
# Python 2 (John): <Person Name="John" />

ElementTree.tostring(xml, encoding='unicode')
# Python 3 (???): <Person Name="???" />             <-------- Python 3
# Python 3 (John): <Person Name="John" />

# Python 2 (???): LookupError: unknown encoding: unicode
# Python 2 (John): LookupError: unknown encoding: unicode

ElementTree.tostring(xml, encoding='utf-8')
# Python 3 (???): b'<Person Name="\xed\x81\xac\xeb\xa6\xac\xec\x8a\xa4" />'
# Python 3 (John): b'<Person Name="John" />'

# Python 2 (???): <Person Name="???" />             <-------- Python 2
# Python 2 (John): <Person Name="John" />

# Python 3 (???): <Person Name="&#53356;&#47532;&#49828;" />
# Python 3 (John): <Person Name="John" />

# Python 2 (???): <Person Name="&#53356;&#47532;&#49828;" />
# Python 2 (John): <Person Name="John" />

How do you see recent SVN log entries?

In case anybody is looking at this old question, a handy command to see the changes since your last update:

svn log -r $(svn info | grep Revision | cut -f 2 -d ' '):HEAD -v

LE (thanks Gary for the comment)
same thing, but much shorter and more logical:

svn log -r BASE:HEAD -v

In Python, how to check if a string only contains certain characters?

Simpler approach? A little more Pythonic?

>>> ok = "0123456789abcdef"
>>> all(c in ok for c in "123456abc")
>>> all(c in ok for c in "hello world")

It certainly isn't the most efficient, but it's sure readable.

Why can't I see the "Report Data" window when creating reports?

Hi I faced the same issue in VS2008, I tried based on the post 8 (Thanks to the "Tricky part" section in that)

The (Ctrl+Alt+D) combo did not work there in VS2008, but after opening the Report file(rdlc) I browsed on the View menu and found out that View->Toolbars->Data Design is the solution for that.

Upon opening that we get around 4 icons of which the "Show Data Sources" section brings the "Website Data Sources" section which fetches all Entities, Typed DataSets etc.

The keybord shortcut is (Shift+Alt+D).

The twisty part here is the "Data Sources" section available with the Server Explorer toolbar doesnt bring up any stuff but the "Website Data Sources" brings all the needed., can somebody explain that to me.

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

For horizontal only, you can trick the box-shadow using overflow on its parent div:

<div class="parent">
  <div class="box-shadow">content</div>

  box-shadow: box-shadow: 0 5px 5px 0 #000;

Can multiple different HTML elements have the same ID if they're different elements?

Can multiple elements have the same ID?

Yes - whether they are the same tag or not, browsers will render the page even if multiple elements have the same ID.

Is it Valid HTML?

No. This is still true as of the HTML 5.1 spec. However, the spec also says getElementById must return the first element with the given ID, making the behavior not undefined in the case of an invalid document.

What are the consequences of this type of invalid HTML?

Most (if not all) browsers have selected and still do select the first element with a given ID, when calling getElementById. Most libraries that find elements by ID inherit this behavior. Most (if not all) browsers also apply styles assigned by id-selectors (e.g. #myid) to all elements with the specified ID. If this is what you expect and intend, then there are no unintended consequences. If you expect/intend something else (e.g. for all elements with that ID to be returned, or for the style to apply to only one element) then your expectations will not be met and any feature relying on those expectations will fail.

Some javascript libraries do have expectations that are not met when multiple elements have the same ID (see wootscootinboogie's comment about d3.js)


It's best to stick to the standards, but if you know your code works as expected in your current environments, and these IDs are used in a predictable/maintainable way, then there are only 2 practical reasons not to do this:

  1. To avoid the chance that you are wrong, and one of the libraries you use actually does malfunction when multiple elements have the same ID.
  2. To maintain forward-compatibility of your website/application with libraries or services (or developers!) you may encounter in the future, that do malfunction when multiple elements have the same ID - which is a reasonable possibility since this is not, technically, valid HTML.

The power is yours!

Keystore change passwords

KeyStore Explorer is an open source GUI replacement for the Java command-line utilities keytool and jarsigner. KeyStore Explorer presents their functionality, and more, via an intuitive graphical user interface.

  1. Open an existing KeyStore
  2. Tools -> Set KeyStore password

How to make a 3D scatter plot in Python?

Use the following code it worked for me:

# Create the figure
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

# Generate the values
x_vals = X_iso[:, 0:1]
y_vals = X_iso[:, 1:2]
z_vals = X_iso[:, 2:3]

# Plot the values
ax.scatter(x_vals, y_vals, z_vals, c = 'b', marker='o')

while X_iso is my 3-D array and for X_vals, Y_vals, Z_vals I copied/used 1 column/axis from that array and assigned to those variables/arrays respectively.

What is the newline character in the C language: \r or \n?

It's \n. When you're reading or writing text mode files, or to stdin/stdout etc, you must use \n, and C will handle the translation for you. When you're dealing with binary files, by definition you are on your own.

How can I show a message box with two buttons?

Cannot be done. MsgBox buttons can only have specific values.
You'll have to roll your own form for this.

To create a MsgBox with two options (Yes/No):

MsgBox("Some Text", vbYesNo)


I haven't done anything with rank, but I discovered this today with row_number().

select item, name, sold, row_number() over(partition by item order by sold) as row from table_name

This will result in some repeating row numbers since in my case each name holds all items. Each item will be ordered by how many were sold.

|glasses |store1|  30 | 1  |
|glasses |store2|  35 | 2  |
|glasses |store3|  40 | 3  |
|shoes   |store2|  10 | 1  |
|shoes   |store1|  20 | 2  |
|shoes   |store3|  22 | 3  |

android layout with visibility GONE

Done by having it like that:

view = inflater.inflate(R.layout.entry_detail, container, false);
TextView tp1= (TextView) view.findViewById(;
LinearLayout layone= (LinearLayout) view.findViewById(;

How can I create directories recursively?

os.makedirs is what you need. For chmod or chown you'll have to use os.walk and use it on every file/dir yourself.

How to apply !important using .css()?

Another easy method to solve this issue adding the style attribute:

$('.selector').attr('style', 'width:500px !important');

Comparing boxed Long values 127 and 128


Java caches boxed Integer instances from -128 to 127. Since you are using == to compare objects references instead of values, only cached objects will match. Either work with long unboxed primitive values or use .equals() to compare your Long objects.

Long (pun intended) version

Why there is problem in comparing Long variable with value greater than 127? If the data type of above variable is primitive (long) then code work for all values.

Java caches Integer objects instances from the range -128 to 127. That said:

  • If you set to N Long variables the value 127 (cached), the same object instance will be pointed by all references. (N variables, 1 instance)
  • If you set to N Long variables the value 128 (not cached), you will have an object instance pointed by every reference. (N variables, N instances)

That's why this:

Long val1 = 127L;
Long val2 = 127L;

System.out.println(val1 == val2);

Long val3 = 128L;
Long val4 = 128L;

System.out.println(val3 == val4);

Outputs this:


For the 127L value, since both references (val1 and val2) point to the same object instance in memory (cached), it returns true.

On the other hand, for the 128 value, since there is no instance for it cached in memory, a new one is created for any new assignments for boxed values, resulting in two different instances (pointed by val3 and val4) and returning false on the comparison between them.

That happens solely because you are comparing two Long object references, not long primitive values, with the == operator. If it wasn't for this Cache mechanism, these comparisons would always fail, so the real problem here is comparing boxed values with == operator.

Changing these variables to primitive long types will prevent this from happening, but in case you need to keep your code using Long objects, you can safely make these comparisons with the following approaches:

System.out.println(val3.equals(val4));                     // true
System.out.println(val3.longValue() == val4.longValue());  // true
System.out.println((long)val3 == (long)val4);              // true

(Proper null checking is necessary, even for castings)

IMO, it's always a good idea to stick with .equals() methods when dealing with Object comparisons.

Reference links:

How to use Python's pip to download and keep the zipped files for a package?

Use pip download <package1 package2 package n> to download all the packages including dependencies

Use pip install --no-index --find-links . <package1 package2 package n> to install all the packages including dependencies. It gets all the files from CWD. It will not download anything

select certain columns of a data table

The question I would ask is, why are you including the extra columns in your DataTable if they aren't required?

Maybe you should modify your SQL select statement so that it is looking at the specific criteria you are looking for as you are populating your DataTable.

You could also use LINQ to query your DataTable as Enumerable and create a List Object that represents only certain columns.

Other than that, hide the DataGridView Columns that you don't require.

Windows 8.1 gets Error 720 on connect VPN

First I would like to thank Rose who was willing to help us, but your answer could solve the problem on a computer, but in others there was what was done could not always connect gets error 720. After much searching and contact the Microsoft support we can solve. In Device Manager, on the View menu, select to show hidden devices. Made it look for a remote Miniport IP or network monitor that is with warning of problems with the driver icon. In its properties in the details tab check the Key property of the driver. Look for this key in Regedit on Local Machine, make a backup of that key and delete it. Restart your windows. Reopen your device manager and select the miniport that had deleted the record. Activate the option to update the driver and look for the option driver on the computer manually and then use the option to locate the driver from the list available on the computer on the next screen uncheck show compatible hardware. Then you must select the Microsoft Vendor and the driver WAN Miniport the type that is changing, IP or IPV6 L2TP Network Monitor. After upgrading restart the computer.

I know it's a bit laborious but that was the only way that worked on all computers.

PHP Session timeout

<script type="text/javascript">

In the header of every page has been working for me during site tests(the site is not yet in production). The HTML page it falls to ends the session and just informs the user of the need to log in again. This seems an easier way than playing with PHP logic. I'd love some comments on the idea. Any traps I havent seen in it ?

Extract first and last row of a dataframe in pandas

The accepted answer duplicates the first row if the frame only contains a single row. If that's a concern

df[0::len(df)-1 if len(df) > 1 else 1]

works even for single row-dataframes.

Example: For the following dataframe this will not create a duplicate:

df = pd.DataFrame({'a': [1], 'b':['a']})
df2 = df[0::len(df)-1 if len(df) > 1  else 1]

print df2

   a  b
0  1  a

whereas this does:

df3 = df.iloc[[0, -1]]

print df3 

   a  b
0  1  a
0  1  a

because the single row is the first AND last row at the same time.

How can I increment a char?

For me i made the fallowing as a test.


def test(string_1):
   i = 0
   p = ""
   x = len(string_1)
   while i < x:
    y = (string_1)[i]
    s = chr(ord(y) + 1)



PHP Pass by reference in foreach

I got here just by accident and the OP's question got my attention. Unfortunately I do not understand any of the explanations from the top. Seems to me like everybody knows it, gets it, accetps it, just cannot explain.

Luckily, a pure sentence from PHP documentation on foreach makes this completely clear:

Warning: Reference of a $value and the last array element remain even after the foreach loop. It is recommended to destroy it by unset().

jquery <a> tag click event

All the hidden fields in your fieldset are using the same id, so jquery is only returning the first one. One way to fix this is to create a counter variable and concatenate it to each hidden field id.

How to replace url parameter with javascript/jquery?

Editing a Parameter The set method of the URLSearchParams object sets the new value of the parameter.

After setting the new value you can get the new query string with the toString() method. This query string can be set as the new value of the search property of the URL object.

The final new url can then be retrieved with the toString() method of the URL object.

var query_string =;

var search_params = new URLSearchParams(query_string); 

// new value of "id" is set to "101"
search_params.set('id', '101');

// change the search property of the main url = search_params.toString();

// the new url string
var new_url = url.toString();

// output :

Source -

Pass table as parameter into sql server UDF

To obtain the column count on a table, use this:

select count(id) from syscolumns where id = object_id('tablename')

and to pass a table to a function, try XML as show here:

create function dbo.ReadXml (@xmlMatrix xml)
returns table
( select
t.value('./@Salary', 'integer') as Salary,
t.value('./@Age', 'integer') as Age
from @xmlMatrix.nodes('//row') x(t)

declare @source table
( Salary integer,
age tinyint
insert into @source
select 10000, 25 union all
select 15000, 27 union all
select 12000, 18 union all
select 15000, 36 union all
select 16000, 57 union all
select 17000, 44 union all
select 18000, 32 union all
select 19000, 56 union all
select 25000, 34 union all
select 7500, 29
--select * from @source

declare @functionArgument xml

select @functionArgument =
( select
Salary as [row/@Salary],
Age as [row/@Age]
from @source
for xml path('')
--select @functionArgument as [@functionArgument]

select * from readXml(@functionArgument)

/* -------- Sample Output: --------
Salary Age
----------- -----------
10000 25
15000 27
12000 18
15000 36
16000 57
17000 44
18000 32
19000 56
25000 34
7500 29

Select n random rows from SQL Server table

Selecting Rows Randomly from a Large Table on MSDN has a simple, well-articulated solution that addresses the large-scale performance concerns.

  SELECT * FROM Table1
  RAND()) as int)) % 100) < 10

How to implement OnFragmentInteractionListener

Answers posted here did not help, but the following link did:

Define an Interface

public class HeadlinesFragment extends ListFragment {
    OnHeadlineSelectedListener mCallback;

    // Container Activity must implement this interface
    public interface OnHeadlineSelectedListener {
        public void onArticleSelected(int position);

    public void onAttach(Activity activity) {

        // This makes sure that the container activity has implemented
        // the callback interface. If not, it throws an exception
        try {
            mCallback = (OnHeadlineSelectedListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement OnHeadlineSelectedListener");


For example, the following method in the fragment is called when the user clicks on a list item. The fragment uses the callback interface to deliver the event to the parent activity.

public void onListItemClick(ListView l, View v, int position, long id) {
    // Send the event to the host activity

Implement the Interface

For example, the following activity implements the interface from the above example.

public static class MainActivity extends Activity
        implements HeadlinesFragment.OnHeadlineSelectedListener{

    public void onArticleSelected(int position) {
        // The user selected the headline of an article from the HeadlinesFragment
        // Do something here to display that article

Update for API 23: 8/31/2015

Overrided method onAttach(Activity activity) is now deprecated in, code should be upgraded to onAttach(Context context)

public void onAttach(Context context) {

public void onStart() {
    try {
        mListener = (OnFragmentInteractionListener) getActivity();
    } catch (ClassCastException e) {
        throw new ClassCastException(getActivity().toString()
                + " must implement OnFragmentInteractionListener");

jQuery append() - return appended elements

// wrap it in jQuery, now it's a collection
var $elements = $(someHTML);

// append to the DOM

// do stuff, using the initial reference
$elements.effects("highlight", {}, 2000);

How to rename a table column in Oracle 10g

suppose supply_master is a table, and

SQL>desc supply_master;


SQL>alter table Supply_master rename column ADDRESS1 TO ADDR;
Table altered

SQL> desc Supply_master;
 ADDR   ///////////this has been renamed........//////////////                

How can strip whitespaces in PHP's variable?

A simple way to remove spaces from the whole string is to use the explode function and print the whole string using a for loop.

 $text = $_POST['string'];
            $a=explode(" ", $text);
            for($i=0;$i<$count; $i++){

                echo $a[$i];

mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in

That query is failing and returning false.

Put this after mysqli_query() to see what's going on.

if (!$check1_res) {
    printf("Error: %s\n", mysqli_error($con));

For more information:

JSON.stringify doesn't work with normal Javascript array

Nice explanation and example above. I found this (JSON.stringify() array bizarreness with Prototype.js) to complete the answer. Some sites implements its own toJSON with JSONFilters, so delete it.

if(window.Prototype) {
    delete Object.prototype.toJSON;
    delete Array.prototype.toJSON;
    delete Hash.prototype.toJSON;
    delete String.prototype.toJSON;

it works fine and the output of the test:




Authentication issue when debugging in VS2013 - iis express

VS 2015 changes this. It added a .vs folder to my web project and the applicationhost.config was in there. I made the changes suggested (window authentication = true, anon=false) and it started delivering a username instead of a blank.

How to drop all tables from a database with one SQL query?

If you want to use only one SQL query to delete all tables you can use this:

EXEC sp_MSforeachtable @command1 = "DROP TABLE ?"

This is a hidden Stored Procedure in sql server, and will be executed for each table in the database you're connected.

Note: You may need to execute the query a few times to delete all tables due to dependencies.

Note2: To avoid the first note, before running the query, first check if there foreign keys relations to any table. If there are then just disable foreign key constraint by running the query bellow:


How to delete a workspace in Perforce (using p4v)?

  1. Ctrl + 5

view workspace in p4v

  1. Delete the relevant workspace

enter image description here

ngFor with index as value in attribute

I think its already been answered before, but just a correction if you are populating an unordered list, the *ngFor will come in the element which you want to repeat. So it should be insdide <li>. Also, Angular2 now uses let to declare a variable.

    <li *ngFor="let item of items; let i = index" []="i">     

How do I get the serial key for Visual Studio Express?

I have an improvement on the answer @DewiMorgan gave for VS 2008 express. I have since confirmed it also works on VS 2005 express.
It lets you run the software without it EVER requiring registration, and also makes it so you don't have to manually delete the key every 30 days. It does this by preventing the key from ever being written.

(Deleting the correct key can also let you avoid registering VS 2015 "Community Edition," but using permissions to prevent the key being written will make the IDE crash, so I haven't found a great solution for it yet.)

The directions assume Visual C# Express 2008, but this works on all the other visual studio express apps I can find.

  1. Open regedit, head to HKEY_CURRENT_USER\Software\Microsoft\VCSExpress\9.0\Registration.
  2. Delete the value Params. picture of me deleting the value 'Params' in the registry.
  3. Right click on the key 'Registration' in the tree, and click permissions.
  4. Click Advanced...
  5. Go to the permissions tab, and uncheck the box labeled Inherit from parent the permission entries that apply to child objects. Include these with entries explicitly defined here. me unchecking the box
  6. In the dialog that opens, click copy.
    the security dialog that pops up
    Note that in Windows 7 (and 8/8.1, I think), it appears the copy button was renamed to add, as in add inherited permissions as explicit permissions.

    In Windows 10, it appears things changed again. @ravuya says that you might have to manually re-create some of the permissions, as the registry editor no longer offers this exact functionality directly. I don't use Windows very much anymore, so I'll defer to them:

    On Win10, there is a button called "Disable Inheritance" that does the same thing as the checkbox mentioned in step 5. It is necessary to create new permissions just for Registration, instead of inheriting those permissions from an upstream registry key.

  7. Hit OK in the 'Advanced' window.
  8. Back in the first permissions window, click your user, and uncheck Full Control. Me unchecking 'full control'

  9. Do the same thing for the Administrators group. Me unchecking 'full control' for the Administrators group

  10. Hit OK or Apply. Congratulations, you will never again be plagued by the registration nag, and just like WinRAR, your trial will never expire.

You may have to do the same thing for other (non-Visual C#) programs, like Visual Basic express or Visual C++ express.

It has been reported by @IronManMark20 in the comments that simply deleting the registry key works and that Visual Studio does not attempt to re-create the key. I am not sure if I believe this because when I installed VS on a clean windows installation, the key was not created until I ran VS at least once. But for what it's worth, that may be an option as well.

String Array object in Java

Currently you can't access the arrays named name and country, because they are member variables of your Athelete class.

Based on what it looks like you're trying to do, this will not work.

These arrays belong in your main class.

Node.js fs.readdir recursive directory search

If you want to use an npm package, wrench is pretty good.

var wrench = require("wrench");

var files = wrench.readdirSyncRecursive("directory");

wrench.readdirRecursive("directory", function (error, files) {
    // live your dreams

EDIT (2018):
Anyone reading through in recent time: The author deprecated this package in 2015:

wrench.js is deprecated, and hasn't been updated in quite some time. I heavily recommend using fs-extra to do any extra filesystem operations.

How to set portrait and landscape media queries in css?

It can also be as simple as this.

@media (orientation: landscape) {


How should the ViewModel close the form?

Here's what I initially did, which does work, however it seems rather long-winded and ugly (global static anything is never good)

1: App.xaml.cs

public partial class App : Application
    // create a new global custom WPF Command
    public static readonly RoutedUICommand LoggedIn = new RoutedUICommand();

2: LoginForm.xaml

// bind the global command to a local eventhandler
<CommandBinding Command="client:App.LoggedIn" Executed="OnLoggedIn" />

3: LoginForm.xaml.cs

// implement the local eventhandler in codebehind
private void OnLoggedIn( object sender, ExecutedRoutedEventArgs e )
    DialogResult = true;

4: LoginFormViewModel.cs

// fire the global command from the viewmodel
private void OnRemoteServerReturnedSuccess()
    App.LoggedIn.Execute(this, null);

I later on then removed all this code, and just had the LoginFormViewModel call the Close method on it's view. It ended up being much nicer and easier to follow. IMHO the point of patterns is to give people an easier way to understand what your app is doing, and in this case, MVVM was making it far harder to understand than if I hadn't used it, and was now an anti-pattern.

SQL grouping by all the columns

The DISTINCT Keyword

I believe what you are trying to do is:


If you group by all columns, you are just requesting that duplicate data be removed.

For example a table with the following data:

 id |     value      
  1 | foo
  2 | bar
  1 | foo
  3 | something else

If you perform the following query which is essentially the same as SELECT * FROM MyFooTable GROUP BY * if you are assuming * means all columns:

SELECT * FROM MyFooTable GROUP BY id, value;

 id |     value      
  1 | foo
  3 | something else
  2 | bar

It removes all duplicate values, which essentially makes it semantically identical to using the DISTINCT keyword with the exception of the ordering of results. For example:


 id |     value      
  1 | foo
  2 | bar
  3 | something else

JSF(Primefaces) ajax update of several elements by ID's

If the to-be-updated component is not inside the same NamingContainer component (ui:repeat, h:form, h:dataTable, etc), then you need to specify the "absolute" client ID. Prefix with : (the default NamingContainer separator character) to start from root.

<p:ajax process="@this" update="count :subTotal"/>

To be sure, check the client ID of the subTotal component in the generated HTML for the actual value. If it's inside for example a h:form as well, then it's prefixed with its client ID as well and you would need to fix it accordingly.

<p:ajax process="@this" update="count :formId:subTotal"/>

Space separation of IDs is more recommended as <f:ajax> doesn't support comma separation and starters would otherwise get confused.

Add 2 hours to current time in MySQL?

FROM courses 

See Date and Time Functions for other date/time manipulation.

How do I set the background color of Excel cells using VBA?

You can use either:

ActiveCell.Interior.ColorIndex = 28


ActiveCell.Interior.Color = RGB(255,0,0)

Deleting a file in VBA

Here's a tip: are you re-using the file name, or planning to do something that requires the deletion immediately?


You can get VBA to fire the command DEL "C:\TEMP\scratchpad.txt" /F from the command prompt asynchronously using VBA.Shell:

Shell "DEL " & chr(34) & strPath & chr(34) & " /F ", vbHide

Note the double-quotes (ASCII character 34) around the filename: I'm assuming that you've got a network path, or a long file name containing spaces.

If it's a big file, or it's on a slow network connection, fire-and-forget is the way to go. Of course, you never get to see if this worked or not; but you resume your VBA immediately, and there are times when this is better than waiting for the network.

Initializing IEnumerable<string> In C#

You cannot instantiate an interface - you must provide a concrete implementation of IEnumerable.

hidden field in php

Yes, you can access it through GET and POST (trying this simple task would have made you aware of that).

Yes, there are other ways, one of the other "preferred" ways is using sessions. When you would want to use hidden over session is kind of touchy, but any GET / POST data is easily manipulated by the end user. A session is a bit more secure given it is saved to a file on the server and it is much harder for the end user to manipulate without access through the program.

Drop shadow for PNG image in CSS

Maybe you are in search of this.

img { png-shadow: 5px 5px 5px #222; }

What is meant by immutable?

An immutable object is the one you cannot modify after you create it. A typical example are string literals.

A D programming language, which becomes increasingly popular, has a notion of "immutability" through "invariant" keyword. Check this Dr.Dobb's article about it - . It explains the problem perfectly.

Cannot use mkdir in home directory: permission denied (Linux Lubuntu)

As @kirbyfan64sos notes in a comment, /home is NOT your home directory (a.k.a. home folder):

The fact that /home is an absolute, literal path that has no user-specific component provides a clue.

While /home happens to be the parent directory of all user-specific home directories on Linux-based systems, you shouldn't even rely on that, given that this differs across platforms: for instance, the equivalent directory on macOS is /Users.

What all Unix platforms DO have in common are the following ways to navigate to / refer to your home directory:

  • Using cd with NO argument changes to your home dir., i.e., makes your home dir. the working directory.
    • e.g.: cd # changes to home dir; e.g., '/home/jdoe'
  • Unquoted ~ by itself / unquoted ~/ at the start of a path string represents your home dir. / a path starting at your home dir.; this is referred to as tilde expansion (see man bash)
    • e.g.: echo ~ # outputs, e.g., '/home/jdoe'
  • $HOME - as part of either unquoted or preferably a double-quoted string - refers to your home dir. HOME is a predefined, user-specific environment variable:
    • e.g.: cd "$HOME/tmp" # changes to your personal folder for temp. files

Thus, to create the desired folder, you could use:

mkdir "$HOME/bin"  # same as: mkdir ~/bin

Note that most locations outside your home dir. require superuser (root user) privileges in order to create files or directories - that's why you ran into the Permission denied error.

Converting HTML to XML

I did found a way to convert (even bad) html into well formed XML. I started to base this on the DOM loadHTML function. However during time several issues occurred and I optimized and added patches to correct side effects.

  function tryToXml($dom,$content) {
    if(!$content) return false;

    // xml well formed content can be loaded as xml node tree
    $fragment = $dom->createDocumentFragment();
    // wonderfull appendXML to add an XML string directly into the node tree!

    // aappendxml will fail on a xml declaration so manually skip this when occurred
    if( substr( $content,0, 5) == '<?xml' ) {
      $content = substr($content,strpos($content,'>')+1);
      if( strpos($content,'<') ) {
        $content = substr($content,strpos($content,'<'));

    // if appendXML is not working then use below htmlToXml() for nasty html correction
    if(!@$fragment->appendXML( $content )) {
      return $this->htmlToXml($dom,$content);

    return $fragment;

  // convert content into xml
  // dom is only needed to prepare the xml which will be returned
  function htmlToXml($dom, $content, $needEncoding=false, $bodyOnly=true) {

    // no xml when html is empty
    if(!$content) return false;

    // real content and possibly it needs encoding
    if( $needEncoding ) {
      // no need to convert character encoding as loadHTML will respect the content-type (only)
      $content =  '<meta http-equiv="Content-Type" content="text/html;charset='.$this->encoding.'">' . $content;

    // return a dom from the content
    $domInject = new DOMDocument("1.0", "UTF-8");
    $domInject->preserveWhiteSpace = false;
    $domInject->formatOutput = true;

    // html type
    try {
      @$domInject->loadHTML( $content );
    } catch(Exception $e){
      // do nothing and continue as it's normal that warnings will occur on nasty HTML content
        // to check encoding: echo $dom->encoding
        $this->reworkDom( $domInject );

    if( $bodyOnly ) {
      $fragment = $dom->createDocumentFragment();

      // retrieve nodes within /html/body
      foreach( $domInject->documentElement->childNodes as $elementLevel1 ) {
       if( $elementLevel1->nodeName == 'body' and $elementLevel1->nodeType == XML_ELEMENT_NODE ) {
         foreach( $elementLevel1->childNodes as $elementInject ) {
           $fragment->insertBefore( $dom->importNode($elementInject, true) );
    } else {
      $fragment = $dom->importNode($domInject->documentElement, true);

    return $fragment;

    protected function reworkDom( $node, $level = 0 ) {

        // start with the first child node to iterate
        $nodeChild = $node->firstChild;

        while ( $nodeChild )  {
            $nodeNextChild = $nodeChild->nextSibling;

            switch ( $nodeChild->nodeType ) {
                case XML_ELEMENT_NODE:
                    // iterate through children element nodes
                    $this->reworkDom( $nodeChild, $level + 1);
                case XML_TEXT_NODE:
                case XML_CDATA_SECTION_NODE:
                    // do nothing with text, cdata
                case XML_COMMENT_NODE:
                    // ensure comments to remove - sign also follows the w3c guideline
                    $nodeChild->nodeValue = str_replace("-","_",$nodeChild->nodeValue);
                case XML_DOCUMENT_TYPE_NODE:  // 10: needs to be removed
                case XML_PI_NODE: // 7: remove PI
                    $node->removeChild( $nodeChild );
                    $nodeChild = null; // make null to test later
                case XML_DOCUMENT_NODE:
                    // should not appear as it's always the root, just to be complete
                    // however generate exception!
                case XML_HTML_DOCUMENT_NODE:
                    // should not appear as it's always the root, just to be complete
                    // however generate exception!
                    throw new exception("Engine: reworkDom type not declared [".$nodeChild->nodeType. "]");
            $nodeChild = $nodeNextChild;
        } ;

Now this also allows to add more html pieces into one XML which I needed to use myself. In general it can be used like this:

    $dom=new DOMDocument('1.0', 'UTF-8');

$n=$dom->appendChild($dom->createElement('info')); // make a root element

if( $valueXml=tryToXml($dom,$c) ) {
    echo '<pre/>'. htmlentities($dom->saveXml($n)). '</pre>';

In this example '<p>test<font>two</p>' will nicely be outputed in well formed XML as '<info><p>test<font>two</font></p></info>'. The info root tag is added as it will also allow to convert '<p>one</p><p>two</p>' which is not XML as it has not one root element. However if you html does for sure have one root element then the extra root <info> tag can be skipped.

With this I'm getting real nice XML out of unstructured and even corrupted HTML!

I hope it's a bit clear and might contribute to other people to use it.

Parsing query strings on Android

public static Map<String, List<String>> getUrlParameters(String url)
        throws UnsupportedEncodingException {
    Map<String, List<String>> params = new HashMap<String, List<String>>();
    String[] urlParts = url.split("\\?");
    if (urlParts.length > 1) {
        String query = urlParts[1];
        for (String param : query.split("&")) {
            String pair[] = param.split("=", 2);
            String key = URLDecoder.decode(pair[0], "UTF-8");
            String value = "";
            if (pair.length > 1) {
                value = URLDecoder.decode(pair[1], "UTF-8");
            List<String> values = params.get(key);
            if (values == null) {
                values = new ArrayList<String>();
                params.put(key, values);
    return params;

How to auto adjust table td width from the content

Remove all widths set using CSS and set white-space to nowrap like so:

.content-loader tr td {
    white-space: nowrap;

I would also remove the fixed width from the container (or add overflow-x: scroll to the container) if you want the fields to display in their entirety without it looking odd...

See more here:

How to change font size on part of the page in LaTeX?

The use of the package \usepackage{fancyvrb} allows the definition of the fontsize argument inside Verbatim:

print "Hello, World"

The fontsize that you can specify are the common


Question mark and colon in statement. What does it mean?

It means if "OperationURL[1]" evaluates to "GET" then return "GetRequestSignature()" else return "". I'm guessing "GetRequestSignature()" here returns a string. The syntax CONDITION ? A : B basically stands for an if-else where A is returned when CONDITION is true and B is returned when CONDITION is false.

Sqlite or MySql? How to decide?

The sqlite team published an article explaining when to use sqlite that is great read. Basically, you want to avoid using sqlite when you have a lot of write concurrency or need to scale to terabytes of data. In many other cases, sqlite is a surprisingly good alternative to a "traditional" database such as MySQL.

Write and read a list from file

As long as your file has consistent formatting (i.e. line-breaks), this is easy with just basic file IO and string operations:

with open('my_file.txt', 'rU') as in_file:
    data ='\n')

That will store your data file as a list of items, one per line. To then put it into a file, you would do the opposite:

with open('new_file.txt', 'w') as out_file:
    out_file.write('\n'.join(data)) # This will create a string with all of the items in data separated by new-line characters

Hopefully that fits what you're looking for.

What are the file limits in Git (number and size)?

I found this trying to store a massive number of files(350k+) in a repo. Yes, store. Laughs.

$ time git add . 
git add . 333.67s user 244.26s system 14% cpu 1:06:48.63 total

The following extracts from the Bitbucket documentation are quite interesting.

When you work with a DVCS repository cloning, pushing, you are working with the entire repository and all of its history. In practice, once your repository gets larger than 500MB, you might start seeing issues.

... 94% of Bitbucket customers have repositories that are under 500MB. Both the Linux Kernel and Android are under 900MB.

The recommended solution on that page is to split your project into smaller chunks.

AngularJs $ does not send data

If using Angular >= 1.4, here's the cleanest solution using the serializer provided by Angular:

  .config(function ($httpProvider, $httpParamSerializerJQLikeProvider){
    $['Content-Type'] = 'application/x-www-form-urlencoded; charset=utf-8';

And then you can simply do this anywhere in your app:

  method: 'POST',
  url: '/requesturl',
  data: {
    param1: 'value1',
    param2: 'value2'

And it will correctly serialize the data as param1=value1&param2=value2 and send it to /requesturl with the application/x-www-form-urlencoded; charset=utf-8 Content-Type header as it's normally expected with POST requests on endpoints.


During my research I found that the answer to this problem comes in many different flavors; some are very convoluted and depend on custom functions, some depend on jQuery and and some are incomplete in suggesting that you only need to set the header.

If you just set the Content-Type header, the end point will see the POST data, but it won't be in the standard format because unless you provide a string as your data, or manually serialize your data object, it will all be serialized as JSON by default and may be incorrectly interpreted at the endpoint.

e.g. if the correct serializer was not set in the above example, it would be seen in the endpoint as:


And that can lead to unexpected parsing, e.g. ASP.NET treats it as a null parameter name, with {"param1":"value1","param2":"value2"} as value; or Fiddler interprets it the other way, with {"param1":"value1","param2":"value2"} as the parameter name, and null as the value.

How to run Linux commands in Java?

Runtime run = Runtime.getRuntime();  
//The best possible I found is to construct a command which you want to execute  
//as a string and use that in exec. If the batch file takes command line arguments  
//the command can be constructed a array of strings and pass the array as input to  
//the exec method. The command can also be passed externally as input to the method.  

Process p = null;  
String cmd = "ls";  
try {  
    p = run.exec(cmd);  


catch (IOException e) {  


Removing trailing newline character from fgets() input

The function below is a part of string processing library I am maintaining on Github. It removes and unwanted characters from a string, exactly what you want

int zstring_search_chr(const char *token,char s){
    if (!token || s=='\0')
        return 0;

    for (;*token; token++)
        if (*token == s)
            return 1;

    return 0;

char *zstring_remove_chr(char *str,const char *bad) {
    char *src = str , *dst = str;
            *dst++ = *src++;  /* assign first, then incement */

        return str;

An example usage could be

Example Usage
      char s[]="this is a trial string to test the function.";
      char const *d=" .";

  Example Output

You may want to check other available functions, or even contribute to the project :)

Rails: How does the respond_to block work?

From what I know, respond_to is a method attached to the ActionController, so you can use it in every single controller, because all of them inherits from the ActionController. Here is the Rails respond_to method:

def respond_to(&block)
  responder =

You are passing it a block, like I show here:

respond_to <<**BEGINNING OF THE BLOCK**>> do |format|
  format.xml  { render :xml => @whatever }
end <<**END OF THE BLOCK**>>

The |format| part is the argument that the block is expecting, so inside the respond_to method we can use that. How?

Well, if you notice we pass the block with a prefixed & in the respond_to method, and we do that to treat that block as a Proc. Since the argument has the ".xml", ".html" we can use that as methods to be called.

What we basically do in the respond_to class is call methods ".html, .xml, .json" to an instance of a Responder class.

Random strings in Python

This function generates random string consisting of upper,lowercase letters, digits, pass the length seperator, no_of_blocks to specify your string format

eg: len_sep = 4, no_of_blocks = 4 will generate the following pattern,


Where, length seperator will add "-" after 4 characters


no of blocks will generate the following patten of characters as string


if a single random string is needed, just keep the no_of_blocks variable to be equal to 1 and len_sep to specify the length of the random string.

eg: len_sep = 10, no_of_blocks = 1, will generate the following pattern ie. random string of length 10,


import random as r

def generate_random_string(len_sep, no_of_blocks):
    random_string = ''
    random_str_seq = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    for i in range(0,len_sep*no_of_blocks):
        if i % len_sep == 0 and i != 0:
            random_string += '-'
        random_string += str(random_str_seq[r.randint(0, len(random_str_seq) - 1)])
    return random_string

C99 stdint.h header and MS Visual Studio

Just define them yourself.

#ifdef _MSC_VER

typedef __int32 int32_t;
typedef unsigned __int32 uint32_t;
typedef __int64 int64_t;
typedef unsigned __int64 uint64_t;

#include <stdint.h>

Get public/external IP address?

Fast way to get External ip without any connection Actualy no need any Http connection for that

first you must add NATUPNPLib.dll on Referance And select it from referances and check from properties window Embed Interop Type to False

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using NATUPNPLib; // Add this dll from referance and chande Embed Interop Interop to false from properties panel on visual studio
using System.Net;

namespace Client
        //This is code for get external ip
        private void NAT_TRAVERSAL_ACT()
            UPnPNATClass uPnP = new UPnPNATClass();
            IStaticPortMappingCollection map = uPnP.StaticPortMappingCollection;

            foreach (IStaticPortMapping item in map)
                    Debug.Print(item.ExternalIPAddress); //This line will give you external ip as string

Cannot find JavaScriptSerializer in .Net 4.0

I'm using Visual Studio 2015 and finally ran across this post.

Yes in order to use

JavaScriptSerializer json = new JavaScriptSerializer();

You must right click on references and under Assemblies --> Framework choose


Then add in your reference

using System.Web.Script.Serialization;

Display JSON as HTML

Could use JSON2HTML to transform it to nicely formatted HTML list .. may be a little more powerful than you really need though

Python xml ElementTree from a string source?

You can parse the text as a string, which creates an Element, and create an ElementTree using that Element.

import xml.etree.ElementTree as ET
tree = ET.ElementTree(ET.fromstring(xmlstring))

I just came across this issue and the documentation, while complete, is not very straightforward on the difference in usage between the parse() and fromstring() methods.

Solving "DLL load failed: %1 is not a valid Win32 application." for Pygame

Had this issue on Python 2.7.9, solved by updating to Python 2.7.10 (unreleased when this question was asked and answered).

CSS disable hover effect

Do this Html and the CSS is in the head tag. Just make a new class and in the css use this code snippet:


<!DOCTYPE html>
<html lang="en">
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
      .buttonDisabled {
        pointer-events: none;
    <button class="buttonDisabled">Not-a-button</button>

Why can't I have abstract static methods in C#?

We actually override static methods (in delphi), it's a bit ugly, but it works just fine for our needs.

We use it so the classes can have a list of their available objects without the class instance, for example, we have a method that looks like this:

class function AvailableObjects: string; override;
  Result := 'Object1, Object2';

It's ugly but necessary, this way we can instantiate just what is needed, instead of having all the classes instantianted just to search for the available objects.

This was a simple example, but the application itself is a client-server application which has all the classes available in just one server, and multiple different clients which might not need everything the server has and will never need an object instance.

So this is much easier to maintain than having one different server application for each client.

Hope the example was clear.

How to pass multiple parameters in thread in VB

Dim evaluator As New Thread(Sub() Me.testthread(goodList, 1))
With evaluator
.IsBackground = True ' not necessary...
End With

What is a simple command line program or script to backup SQL server databases?

I found this on a Microsoft Support page

It works great! And since it came from Microsoft, I feel like it's pretty legit.

Basically there are two steps.

  1. Create a stored procedure in your master db. See msft link or if it's broken try here:
  2. Schedule the backup from your task scheduler. You might want to put into a .bat or .cmd file first and then schedule that file.

    sqlcmd -S YOUR_SERVER_NAME\SQLEXPRESS -E -Q "EXEC sp_BackupDatabases @backupLocation='C:\SQL_Backup\', @backupType='F'"  1>c:\SQL_Backup\backup.log            

Obviously replace YOUR_SERVER_NAME with your computer name or optionally try .\SQLEXPRESS and make sure the backup folder exists. In this case it's trying to put it into c:\SQL_Backup

.NET code to send ZPL to Zebra printers

Figured since this is still showing up high in search results for C# and ZPL I should mention SharpZebra. It's only EPL2, but I've submitted an update that adds ZPL support along with printing via sockets, the Windows Spool Service and direct USB.

Convert a SQL query result table to an HTML table for email

JustinStolle's answer in a different way. A few notes:

  • The print statement may truncate the string to 4000 characters, but my test string for example was 9520 characters in length.
  • The [tr/th] indicates hierarchy, e.g., <tr><th>...</th></tr>.
  • The [@name] adds fields as XML attributes.
  • MS SQL XML concatenates fields of the same name, so null in between fields prevents that.

declare @body nvarchar(max)

select @body = cast((
    select N'2' [@cellpadding], N'2' [@cellspacing], N'1' [@border],
           N'Database Table' [tr/th], null [tr/td],
           N'Entity Count' [tr/th], null [tr/td],
           N'Total Rows' [tr/th], null,
           (select  object_name( object_id ) [td], null,
                    count( distinct name ) [td], null,
                    count( * )  [td], null
             from sys.columns
             group by object_name( object_id )
             for xml path('tr'), type)
        for xml path('table'), type
        ) as nvarchar(max))

print @body  -- only shows up to 4000 characters depending

BAT file to map to network drive without running as admin

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

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

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

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

for more details, refer New-PSDrive - Microsoft Docs

How to change the font color of a disabled TextBox?

Just handle Enable changed and set it to the color you need

private void TextBoxName_EnabledChanged(System.Object sender, System.EventArgs e)
    ((TextBox)sender).ForeColor = Color.Black;

Printing out a linked list using toString

A very simple solution is to override the toString() method in the Node. Then, you can call print by passing LinkedList's head. You don't need to implement any kind of loop.


public class LinkedListNode {

    public String toString() {
        return String.format("Node(%d, next = %s)", data, next);

public class LinkedList {

    public static void main(String[] args) {

        LinkedList l = new LinkedList();


Enable IIS7 gzip

Another easy way to test without installing anything, neither is it dependent on IIS version. Paste your url to this link - SEO Checkup

test gzip

To add to web.config:

What is the difference between ndarray and array in numpy?

I think with np.array() you can only create C like though you mention the order, when you check using np.isfortran() it says false. but with np.ndarrray() when you specify the order it creates based on the order provided.

Converting a year from 4 digit to 2 digit and back again in C#

I've seen some systems decide that the cutoff is 75; 75+ is 19xx and below is 20xx.

How to throw RuntimeException ("cannot find symbol")

throw new RuntimeException(msg); // notice the "new" keyword