Programs & Examples On #Xcode3.2

The June 2009 release of Xcode, Apple's integrated development environment (IDE) for its Mac OS X and iOS platforms.

Undefined symbols for architecture i386

well i found a solution to this problem for who want to work with xCode 4. All what you have to do is importing frameworks from the SimulatorSDK folder /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks

i don't know if it works when you try to test your app on a real iDevice, but i'm sure that it works on simulator.


scikit-learn random state in splitting dataset

The random_state is an integer value which implies the selection of a random combination of train and test. When you set the test_size as 1/4 the there is a set generated of permutation and combination of train and test and each combination has one state. Suppose you have a dataset---> [1,2,3,4]

Train   |  Test   | State
[1,2,3]    [4]      **0**
[1,3,4]    [2]      **1**
[4,2,3]    [1]      **2**
[2,4,1]    [3]      **3**

We need it because while param tuning of model same state will considered again and again. So that there won't be any inference with the accuracy.

But in case of Random forest there is also similar story but in a different way w.r.t the variables.

Load data from txt with pandas

If you want to load the txt file with specified column name, you can use the code below. It worked for me.

import pandas as pd    
data = pd.read_csv('file_name.txt', sep = "\t", names = ['column1_name','column2_name', 'column3_name'])

combining two data frames of different lengths

It's not clear to me at all what the OP is actually after, given the follow-up comments. It's possible they are actually looking for a way to write the data to file.

But let's assume that we're really after a way to cbind multiple data frames of differing lengths.

cbind will eventually call data.frame, whose help files says:

Objects passed to data.frame should have the same number of rows, but atomic vectors, factors and character vectors protected by I will be recycled a whole number of times if necessary (including as from R 2.9.0, elements of list arguments).

so in the OP's actual example, there shouldn't be an error, as R ought to recycle the shorter vectors to be of length 50. Indeed, when I run the following:

a <- runif(50)
b <- 1:50
c <- rep(LETTERS[1:5],length.out = 50)
dat1 <- data.frame(a,b,c)
dat2 <- data.frame(d = runif(10),e = runif(10))

I get no errors and the shorter data frame is recycled as expected. However, when I run this:

a <- runif(50)
b <- 1:50
c <- rep(LETTERS[1:5],length.out = 50)
dat1 <- data.frame(a,b,c)
dat2 <- data.frame(d = runif(9), e = runif(9))

I get the following error:

Error in data.frame(..., check.names = FALSE) : 
  arguments imply differing number of rows: 50, 9

But the wonderful thing about R is that you can make it do almost anything you want, even if you shouldn't. For example, here's a simple function that will cbind data frames of uneven length and automatically pad the shorter ones with NAs:

cbindPad <- function(...){
args <- list(...)
n <- sapply(args,nrow)
mx <- max(n)
pad <- function(x, mx){
    if (nrow(x) < mx){
        nms <- colnames(x)
        padTemp <- matrix(NA, mx - nrow(x), ncol(x))
        colnames(padTemp) <- nms
        if (ncol(x)==0) {
        } else {
rs <- lapply(args,pad,mx)

which can be used like this:

a <- runif(50)
b <- 1:50
c <- rep(LETTERS[1:5],length.out = 50)
dat1 <- data.frame(a,b,c)
dat2 <- data.frame(d = runif(10),e = runif(10))
dat3 <- data.frame(d = runif(9), e = runif(9))

I make no guarantees that this function works in all cases; it is meant as an example only.


If the primary goal is to create a csv or text file, all you need to do it alter the function to pad using "" rather than NA and then do something like this:

dat <- cbindPad(dat1,dat2,dat3)
rs <-,1,function(x){paste(as.character(x),collapse=",")}))

and then use write.table on rs.

Force file download with php using header()

Here is a snippet from me in testing... obviously passing via get to the script may not be the best... should post or just send an id and grab guid from db... anyhow.. this worked. I take the URL and convert it to a path.

// Initialize a file URL to the variable
$file = $_GET['url'];
$file = str_replace(Polepluginforrvms_Plugin::$install_url, $DOC_ROOT.'/pole-permitter/', $file );

$quoted = sprintf('"%s"', addcslashes(basename($file), '"\\'));
$size   = filesize($file);

header( "Content-type: application/octet-stream" );
header( "Content-Disposition: attachment; filename={$quoted}" );
header( "Content-length: " . $size );
header( "Pragma: no-cache" );
header( "Expires: 0" );
readfile( "{$file}" );

How to add multiple classes to a ReactJS Component?


import classNames from 'classnames';

  1. Can use multiple classes using comas seperated:

    <li className={classNames(classes.tableCellLabel, classes.tableCell)}>Total</li>
  2. Can use multiple classes using comas separated with condition:

    <li className={classNames(classes.buttonArea, !nodes.length && classes.buttonAreaHidden)}>Hello World</li> 

Using array as props to classNames will also work, but gives warning e.g.

className={[classes.tableCellLabel, classes.tableCell]}

How to get URL of current page in PHP

The other answers are correct. However, a quick note: if you're looking to grab the stuff after the ? in a URI, you should use the $_GET[] array.

How can I stop python.exe from closing immediately after I get an output?

You can't - globally, i.e. for every python program. And this is a good thing - Python is great for scripting (automating stuff), and scripts should be able to run without any user interaction at all.

However, you can always ask for input at the end of your program, effectively keeping the program alive until you press return. Use input("prompt: ") in Python 3 (or raw_input("promt: ") in Python 2). Or get used to running your programs from the command line (i.e. python, the program will exit but its output remains visible.

How can I dismiss the on screen keyboard?

To dismiss the keyboard (1.7.8+hotfix.2 and above) just call the method below:


Once the FocusScope.of(context).unfocus() method already check if there is focus before dismiss the keyboard it's not needed to check it. But in case you need it just call another context method: FocusScope.of(context).hasPrimaryFocus

Carriage Return\Line feed in Java

Don't know who looks at your file, but if you open it in wordpad instead of notepad, the linebreaks will show correct. In case you're using a special file extension, associate it with wordpad and you're done with it. Or use any other more advanced text editor.

PHP - Copy image to my server direct from URL

This SO thread will solve your problem. Solution in short:

$url = '';
$img = '/my/folder/my_image.gif';
file_put_contents($img, file_get_contents($url));

Android, getting resource ID from string?

In your res/layout/my_image_layout.xml

<LinearLayout ...>

To grab that ImageView by its @+id value, inside your java code do this:

String row = "0";
String column= "7";
String tileID = "row_" + (row) + "_col_" + (column);
ImageView image = (ImageView) activity.findViewById(activity.getResources()
                .getIdentifier(tileID, "id", activity.getPackageName()));

/*Bottom code changes that ImageView to a different image. "blank" (R.mipmap.blank) is the name of an image I have in my drawable folder. */

Repeat a task with a time delay?

Based on the above post concerning the ScheduledThreadPoolExecutor, I came up with a utility that suited my needs (wanted to fire a method every 3 seconds):

class MyActivity {
    private ScheduledThreadPoolExecutor mDialogDaemon;

    private void initDebugButtons() {
        Button btnSpawnDialogs = (Button)findViewById(;
        btnSpawnDialogs.setOnClickListener(new OnClickListener() {
            public void onClick(View view) {

    private void spawnDialogs() {
        if (mDialogDaemon != null) {
            mDialogDaemon = null;
        mDialogDaemon = new ScheduledThreadPoolExecutor(1);
        // This process will execute immediately, then execute every 3 seconds.
        mDialogDaemon.scheduleAtFixedRate(new Runnable() {
            public void run() {
                runOnUiThread(new Runnable() {
                    public void run() {
                        // Do something worthwhile
        }, 0L, 3000L, TimeUnit.MILLISECONDS);

How to install latest version of openssl Mac OS X El Capitan

this command solve my problem on github CI job and virtualbox

brew install [email protected]
cp /usr/local/opt/[email protected]/lib/pkgconfig/*.pc /usr/local/lib/pkgconfig/

A quick and easy way to join array elements with a separator (the opposite of split) in Java

Using Java 8 you can do this in a very clean way:

String.join(delimiter, elements);

This works in three ways:

1) directly specifying the elements

String joined1 = String.join(",", "a", "b", "c");

2) using arrays

String[] array = new String[] { "a", "b", "c" };
String joined2 = String.join(",", array);

3) using iterables

List<String> list = Arrays.asList(array);
String joined3 = String.join(",", list);

PHP Fatal Error Failed opening required File

Run php -f /common/configs/ to verify the validity of the PHP syntax in the file.

No MediaTypeFormatter is available to read an object of type 'String' from content with media type 'text/plain'

Try using ReadAsStringAsync() instead.

 var foo = resp.Content.ReadAsStringAsync().Result;

The reason why it ReadAsAsync<string>() doesn't work is because ReadAsAsync<> will try to use one of the default MediaTypeFormatter (i.e. JsonMediaTypeFormatter, XmlMediaTypeFormatter, ...) to read the content with content-type of text/plain. However, none of the default formatter can read the text/plain (they can only read application/json, application/xml, etc).

By using ReadAsStringAsync(), the content will be read as string regardless of the content-type.

HTML form with side by side input fields

You should put the input for the last name into the same div where you have the first name.

    <label for="username">First Name</label>
    <input id="user_first_name" name="user[first_name]" size="30" type="text" />
    <input id="user_last_name" name="user[last_name]" size="30" type="text" />

Then, in your CSS give your #user_first_name and #user_last_name height and float them both to the left. For example:

    max-width:100px; /*max-width for responsiveness*/


VS2010 How to include files in project, to copy them to build output directory automatically during build or publish

I only have the need to push files during a build, so I just added a Post-build Event Command Line entry like this:

Copy /Y "$(SolutionDir)Third Party\SomeLibrary\*" "$(TargetDir)"

You can set this by right-clicking your Project in the Solution Explorer, then Properties > Build Events

Filter element based on .data() key/value

Two things I noticed (they may be mistakes from when you wrote it down though).

  1. You missed a dot in the first example ( $('.navlink').click )
  2. For filter to work, you have to return a value ( return $(this).data("selected")==true )

How do you display code snippets in MS Word preserving format and syntax highlighting?

If you are using Android Studio, you can simply copy and paste, and the code aspect is going to be preserved and the colors as well. Simple enough!

What is the best way to test for an empty string with jquery-out-of-the-box?

Try executing this in your browser console or in a node.js repl.

var string = ' ';
string ? true : false;
//-> true

string = '';
string ? true : false;
//-> false

Therefore, a simple branching construct will suffice for the test.

if(string) {
    // string is not empty

Best practice for instantiating a new Android Fragment

The only benefit in using the newInstance() that I see are the following:

  1. You will have a single place where all the arguments used by the fragment could be bundled up and you don't have to write the code below everytime you instantiate a fragment.

    Bundle args = new Bundle();
    args.putInt("someInt", someInt);
    args.putString("someString", someString);
    // Put any other arguments
  2. Its a good way to tell other classes what arguments it expects to work faithfully(though you should be able to handle cases if no arguments are bundled in the fragment instance).

So, my take is that using a static newInstance() to instantiate a fragment is a good practice.

List all environment variables from the command line

You can use SET in cmd

To show the current variable, just SET is enough

To show certain variable such as 'PATH', use SET PATH.

For help, type set /?.

How to group subarrays by a column value?

function groupeByPHP($array,$indexUnique,$assoGroup,$keepInOne){
$retour = array();
$id = $array[0][$indexUnique];
foreach ($keepInOne as $keep){
    $retour[$id][$keep] = $array[0][$keep];
foreach ($assoGroup as $cle=>$arrayKey){
    $arrayGrouped = array();
        foreach ($array as $data){
            if($data[$indexUnique] != $id){
                $id = $data[$indexUnique];
                foreach ($keepInOne as $keep){
                    $retour[$id][$keep] = $data[$keep];
            foreach ($arrayKey as $val){
                $arrayGrouped[$val] = $data[$val];
            $retour[$id][$cle][] = $arrayGrouped;
            $retour[$id][$cle] = array_unique($retour[$id][$cle],SORT_REGULAR);
return  $retour;

Try this function


How to printf "unsigned long" in C?

  • %lu for unsigned long
  • %llu for unsigned long long

MySQL order by before group by

Just to recap, the standard solution uses an uncorrelated subquery and looks like this:

  FROM my_table x
  JOIN (SELECT grouping_criteria,MAX(ranking_criterion) max_n FROM my_table GROUP BY grouping_criteria) y
    ON y.grouping_criteria = x.grouping_criteria
   AND y.max_n = x.ranking_criterion;

If you're using an ancient version of MySQL, or a fairly small data set, then you can use the following method:

  FROM my_table x
  JOIN my_table y
    ON y.joining_criteria = x.joining_criteria
   AND y.ranking_criteria < x.ranking_criteria
 WHERE y.some_non_null_column IS NULL;  

Modify SVG fill color when being served as Background-Image

You can use CSS masks, With the 'mask' property, you create a mask that is applied to an element.

.icon {
    background-color: red;
    -webkit-mask-image: url(icon.svg);
    mask-image: url(icon.svg);

For more see this great article:

How to add fixed button to the bottom right of page

This will be helpful for the right bottom rounded button


      <a class="fixedButton" href>
         <div class="roundedFixedBtn"><i class="fa fa-phone"></i></div>


            position: fixed;
            bottom: 0px;
            right: 0px; 
            padding: 20px;
          height: 60px;
          line-height: 80px;  
          width: 60px;  
          font-size: 2em;
          font-weight: bold;
          border-radius: 50%;
          background-color: #4CAF50;
          color: white;
          text-align: center;
          cursor: pointer;

Here is jsfiddle link

Python Pip install Error: Unable to find vcvarsall.bat. Tried all solutions

After doing a lot of things, I upgraded pip, setuptools and virtualenv.

  1. python -m pip install -U pip
  2. pip install -U setuptools
  3. pip install -U virtualenv

I did steps 1, 2 in my virtual environment as well as globally. Next, I installed the package through pip and it worked.

Replace first occurrence of pattern in a string

public string ReplaceFirst(string text, string search, string replace)
  int pos = text.IndexOf(search);
  if (pos < 0)
    return text;
  return text.Substring(0, pos) + replace + text.Substring(pos + search.Length);

here is an Extension Method that could also work as well per VoidKing request

public static class StringExtensionMethods
    public static string ReplaceFirst(this string text, string search, string replace)
      int pos = text.IndexOf(search);
      if (pos < 0)
        return text;
      return text.Substring(0, pos) + replace + text.Substring(pos + search.Length);

bitwise XOR of hex numbers in python

here's a better function

def strxor(a, b):     # xor two strings of different lengths
    if len(a) > len(b):
        return "".join([chr(ord(x) ^ ord(y)) for (x, y) in zip(a[:len(b)], b)])
        return "".join([chr(ord(x) ^ ord(y)) for (x, y) in zip(a, b[:len(a)])])

C# looping through an array

Just increment i by 3 in each step:

  Debug.Assert((theData.Length % 3) == 0);  // 'theData' will always be divisible by 3

  for (int i = 0; i < theData.Length; i += 3)
       //grab 3 items at a time and do db insert, 
       // continue until all items are gone..
       string item1 = theData[i+0];
       string item2 = theData[i+1];
       string item3 = theData[i+2];
       // use the items

To answer some comments, it is a given that theData.Length is a multiple of 3 so there is no need to check for theData.Length-2 as an upperbound. That would only mask errors in the preconditions.

import android packages cannot be resolved

What all the others said.

Specifically, I recommend you go to Project > Properties > Java Build Path > Libraries and make sure you have exactly one copy of android.jar referenced. (Sometimes you can get two if you're importing a project.) And that its path is correct.

Sometimes you can get the system to resolve this for you by clicking a different target SDK in Project > Properties > Android, then restoring your original selection.

paint() and repaint() in Java

It's not necessary to call repaint unless you need to render something specific onto a component. "Something specific" meaning anything that isn't provided internally by the windowing toolkit you're using.

PHP php_network_getaddresses: getaddrinfo failed: No such host is known

IMO it's the different way to resolve a name from the OS and PHP.


echo gethostbyname("");


var_export (dns_get_record ( "") );


var_export (dns_get_record ( "" ,  DNS_ALL , $dns ));

You should found some DNS/resolver error.

How do you display a Toast from a background thread on Android?

Sometimes, you have to send message from another Thread to UI thread. This type of scenario occurs when you can't execute Network/IO operations on UI thread.

Below example handles that scenario.

  1. You have UI Thread
  2. You have to start IO operation and hence you can't run Runnable on UI thread. So post your Runnable to handler on HandlerThread
  3. Get the result from Runnable and send it back to UI thread and show a Toast message.


  1. Create a HandlerThread and start it
  2. Create a Handler with Looper from HandlerThread:requestHandler
  3. Create a Handler with Looper from Main Thread: responseHandler and override handleMessage method
  4. post a Runnable task on requestHandler
  5. Inside Runnable task, call sendMessage on responseHandler
  6. This sendMessage result invocation of handleMessage in responseHandler.
  7. Get attributes from the Message and process it, update UI

Sample code:

    /* Handler thread */

    HandlerThread handlerThread = new HandlerThread("HandlerThread");
    Handler requestHandler = new Handler(handlerThread.getLooper());

    final Handler responseHandler = new Handler(Looper.getMainLooper()) {
        public void handleMessage(Message msg) {
            //txtView.setText((String) msg.obj);
                    "Runnable on HandlerThread is completed and got result:"+(String)msg.obj,

    for ( int i=0; i<5; i++) {
        Runnable myRunnable = new Runnable() {
            public void run() {
                try {

                    /* Add your business logic here and construct the 
                       Messgae which should be handled in UI thread. For 
                       example sake, just sending a simple Text here*/

                    String text = "" + (++rId);
                    Message msg = new Message();

                    msg.obj = text.toString();

                } catch (Exception err) {

Useful articles:



Print array elements on separate lines in Bash?

You could use a Bash C Style For Loop to do what you want.

my_array=(one two three)

for ((i=0; i < ${#my_array[@]}; i++ )); do echo "${my_array[$i]}"; done

CSS: background-color only inside the margin

I needed something similar, and came up with using the :before (or :after) pseudoclasses:

#mydiv {
   background-color: #fbb;
   margin-top: 100px;
   position: relative;
#mydiv:before {
   content: "";
   background-color: #bfb;
   top: -100px;
   height: 100px;
   width: 100%;
   position: absolute;


Retrieve data from a ReadableStream object?

I dislike the chaining thens. The second then does not have access to status. As stated before 'response.json()' returns a promise. Returning the then result of 'response.json()' in a acts similar to a second then. It has the added bonus of being in scope of the response.

return fetch(url, params).then(response => {
    return response.json().then(body => {
        if (response.status === 200) {
            return body
        } else {
            throw body

php/mySQL on XAMPP: password for phpMyAdmin and mysql_connect different?

if you open localhost/phpmyadmin you will find a tab called "User accounts". There you can define all your users that can access the mysql database, set their rights and even limit from where they can connect.

Page redirect with successful Ajax request

I posted the exact situation on a different thread. Re-post.

Excuse me, This is not an answer to the question posted above.

But brings an interesting topic --- WHEN to use AJAX and when NOT to use AJAX. In this case it's good not to use AJAX.

Let's take a simple example of login and password. If the login and/or password does not match it WOULD be nice to use AJAX to report back a simple message saying "Login Incorrect". But if the login and password IS correct, why would I have to callback an AJAX function to redirect to the user page?

In a case like, this I think it would be just nice to use a simple Form SUBMIT. And if the login fails, redirect to Relogin.php which looks same as the Login.php with a GET message in the url like Relogin.php?error=InvalidLogin... something like that...

Just my 2 cents. :)

How do I change tab size in Vim?

:set tabstop=4
:set shiftwidth=4
:set expandtab

This will insert four spaces instead of a tab character. Spaces are a bit more “stable”, meaning that text indented with spaces will show up the same in the browser and any other application.

How to change the date format from MM/DD/YYYY to YYYY-MM-DD in PL/SQL?

To convert a DATE column to another format, just use TO_CHAR() with the desired format, then convert it back to a DATE type:

SELECT TO_DATE(TO_CHAR(date_column, 'DD-MM-YYYY'), 'DD-MM-YYYY') from my_table

How to save and extract session data in codeigniter

initialize the Session class in the constructor of controller using


for example :

 function __construct()

Read a file line by line with VB.NET

Replaced the reader declaration with this one and now it works!

Dim reader As New StreamReader(filetoimport.Text, Encoding.Default)

Encoding.Default represents the ANSI code page that is set under Windows Control Panel.

Difference between $(document.body) and $('body')

They refer to the same element, the difference is that when you say document.body you are passing the element directly to jQuery. Alternatively, when you pass the string 'body', the jQuery selector engine has to interpret the string to figure out what element(s) it refers to.

In practice either will get the job done.

If you are interested, there is more information in the documentation for the jQuery function.

cancelling a handler.postdelayed process

I do this to post a delayed runnable:

myHandler.postDelayed(myRunnable, SPLASH_DISPLAY_LENGTH); 

And this to remove it: myHandler.removeCallbacks(myRunnable);

What is the 'new' keyword in JavaScript?

In addition to Daniel Howard's answer, here is what new does (or at least seems to do):

function New(func) {
    var res = {};
    if (func.prototype !== null) {
        res.__proto__ = func.prototype;
    var ret = func.apply(res,, 1));
    if ((typeof ret === "object" || typeof ret === "function") && ret !== null) {
        return ret;
    return res;


var obj = New(A, 1, 2);

is equivalent to

var obj = new A(1, 2);

Merge 2 DataTables and store in a new one

dtAll = dtOne.Copy();

The parameter TRUE preserve the changes.

For more details refer to MSDN.

batch script - run command on each file in directory

Actually this is pretty easy since Windows Vista. Microsoft added the command FORFILES

in your case

forfiles /p c:\directory /m *.xls /c "cmd /c ssconvert @file @fname.xlsx"

the only weird thing with this command is that forfiles automatically adds double quotes around @file and @fname. but it should work anyway

I got error "The DELETE statement conflicted with the REFERENCE constraint"

To DELETE, without changing the references, you should first delete or otherwise alter (in a manner suitable for your purposes) all relevant rows in other tables.

To TRUNCATE you must remove the references. TRUNCATE is a DDL statement (comparable to CREATE and DROP) not a DML statement (like INSERT and DELETE) and doesn't cause triggers, whether explicit or those associated with references and other constraints, to be fired. Because of this, the database could be put into an inconsistent state if TRUNCATE was allowed on tables with references. This was a rule when TRUNCATE was an extension to the standard used by some systems, and is mandated by the the standard, now that it has been added.

How to switch to other branch in Source Tree to commit the code?

Hi I'm also relatively new but I can give you basic help.

  1. To switch to another branch use "Checkout". Just click on your branch and then on the button "checkout" at the top.

UPDATE 12.01.2016:

The bold line is the current branch.

You can also just double click a branch to use checkout.

  1. Your first answer I think depends on the repository you use (like github or bitbucket). Maybe the "Show hosted repository"-Button can help you (Left panel, bottom, right button = database with cog)

And here some helpful links:

Easy Git Guide

Git-flow - Git branching model

Tips on branching with sourcetree

How to extract file name from path?

I can't believe how overcomplicated some of these answers are... (no offence!)

Here's a single-line function that will get the job done:

**Extract Filename from <code>x:\path\filename</code>:**

Function getFName(pf)As String:getFName=Mid(pf,InStrRev(pf,"\")+1):End Function

**Extract Path from <code>x:\path\filename</code>:**

Function getPath(pf)As String:getPath=Left(pf,InStrRev(pf,"\")):End Function



Transferring files over SSH

No, you still need to scp [from] [to] whichever way you're copying

The difference is, you need to scp -p server:serverpath localpath

How do I create a chart with multiple series using different X values for each series?

You need to use the Scatter chart type instead of Line. That will allow you to define separate X values for each series.

Get first element from a dictionary

Dictionary does not define order of items. If you just need an item use Keys or Values properties of dictionary to pick one.

How to make VS Code to treat other file extensions as certain language?

This works for me.

enter image description here

"files.associations": {"*.bitesize": "yaml"}

Extract month and year from a zoo::yearmon object

Having had a similar problem with data from 1800 to now, this worked for me:

lct <- Sys.getlocale("LC_TIME"); 
data2$date<- as.Date(data2$date, format = "%Y %m %d") # and it works

How to check if a file exists in Go?

The first thing to consider is that it is rare that you would only want to check whether or not a file exists. In most situations, you're trying to do something with the file if it exists. In Go, any time you try to perform some operation on a file that doesn't exist, the result should be a specific error (os.ErrNotExist) and the best thing to do is check whether the return err value (e.g. when calling a function like os.OpenFile(...)) is os.ErrNotExist.

The recommended way to do this used to be:

file, err := os.OpenFile(...)
if os.IsNotExist(err) {
    // handle the case where the file doesn't exist

However, since the addition of errors.Is in Go 1.13 (released in late 2019), the new recommendation is to use errors.Is:

file, err := os.OpenFile(...)
if errors.Is(err, os.ErrNotExist) {
    // handle the case where the file doesn't exist

It's usually best to avoid using os.Stat to check for the existence of a file before you attempt to do something with it, because it will always be possible for the file to be renamed, deleted, etc. in the window of time before you do something with it.

However, if you're OK with this caveat and you really, truly just want to check whether a file exists without then proceeding to do something useful with it (as a contrived example, let's say that you're writing a pointless CLI tool that tells you whether or not a file exists and then exits ¯\_(?)_/¯), then the recommended way to do it would be:

if _, err := os.Stat(filename); errors.Is(err, os.ErrNotExist) {
    // file does not exist
} else {
    // file exists

How to specify different Debug/Release output directories in QMake .pro file

The correct way to do this is the following (thanks QT Support Team):

CONFIG(debug, debug|release) {
    DESTDIR = build/debug
CONFIG(release, debug|release) {
    DESTDIR = build/release


More info here:

Repeat table headers in print mode

Some browsers repeat the thead element on each page, as they are supposed to. Others need some help: Add this to your CSS:

thead {display: table-header-group;}
tfoot {display: table-header-group;}

Opera 7.5 and IE 5 won't repeat headers no matter what you try.


How can I connect to a Tor hidden service using cURL in PHP?

Try to add this:

curl_setopt($ch, CURLOPT_HEADER, 1); 
curl_setopt($ch, CURLOPT_HTTPPROXYTUNNEL, 1); 

Android ADB device offline, can't issue commands

It's just because your computer doesn't have the right driver. To fix that:

  1. Download and extract Android SDK

  2. Go to Device Manager (Right Click on Computer --> Properties --> Device Manager

  3. On the right pane expand portable devices to find your device

  4. Right click on your device name and click Update Driver Software

  5. Browse my computer for driver software

  6. Browse to your Android SDK folder on step 1.

  7. Next and you're done

How do you add a Dictionary of items into another Dictionary


I prefer to combine/unite immutable dictionaries with + operator so I implemented it like:

// Swift 2
func + <K,V> (left: Dictionary<K,V>, right: Dictionary<K,V>?) -> Dictionary<K,V> {
    guard let right = right else { return left }
    return left.reduce(right) {
        var new = $0 as [K:V]
        new.updateValue($1.1, forKey: $1.0)
        return new

let moreAttributes: [String:AnyObject] = ["Function":"authenticate"]
let attributes: [String:AnyObject] = ["File":"Auth.swift"]

attributes + moreAttributes + nil //["Function": "authenticate", "File": "Auth.swift"]    
attributes + moreAttributes //["Function": "authenticate", "File": "Auth.swift"]
attributes + nil //["File": "Auth.swift"]


// Swift 2
func += <K,V> (inout left: Dictionary<K,V>, right: Dictionary<K,V>?) {
    guard let right = right else { return }
    right.forEach { key, value in
        left.updateValue(value, forKey: key)

let moreAttributes: [String:AnyObject] = ["Function":"authenticate"]
var attributes: [String:AnyObject] = ["File":"Auth.swift"]

attributes += nil //["File": "Auth.swift"]
attributes += moreAttributes //["File": "Auth.swift", "Function": "authenticate"]

Start and stop a timer PHP

As alternative, php has a built-in timer controller: new EvTimer().

It can be used to make a task scheduler, with proper handling of special cases.

This is not only the Time, but a time transport layer, a chronometer, a lap counter, just as a stopwatch but with php callbacks ;)

EvTimer watchers are simple relative timers that generate an event after a given time, and optionally repeating in regular intervals after that.

The timers are based on real time, that is, if one registers an event that times out after an hour and resets the system clock to January last year, it will still time out after(roughly) one hour.

The callback is guaranteed to be invoked only after its timeout has passed (...). If multiple timers become ready during the same loop iteration then the ones with earlier time-out values are invoked before ones of the same priority with later time-out values.

The timer itself will do a best-effort at avoiding drift, that is, if a timer is configured to trigger every 10 seconds, then it will normally trigger at exactly 10 second intervals. If, however, the script cannot keep up with the timer because it takes longer than those 10 seconds to do) the timer will not fire more than once per event loop iteration.

The first two parameters allows to controls the time delay before execution, and the number of iterations.

The third parameter is a callback function, called at each iteration.


    Configures the timer to trigger after after seconds.


    If repeat is 0.0 , then it will automatically be stopped once the timeout is reached.
    If it is positive, then the timer will automatically be configured to trigger again every repeat seconds later, until stopped manually.

$w2 = new EvTimer(2, 1, function ($w) {
    echo "is called every second, is launched after 2 seconds\n";
    echo "iteration = ", Ev::iteration(), PHP_EOL;

    // Stop the watcher after 5 iterations
    Ev::iteration() == 5 and $w->stop();
    // Stop the watcher if further calls cause more than 10 iterations
    Ev::iteration() >= 10 and $w->stop();

We can of course easily create this with basic looping and some tempo with sleep(), usleep(), or hrtime(), but new EvTimer() allows cleans and organized multiples calls, while handling special cases like overlapping.

How to add a TextView to a LinearLayout dynamically in Android?

TextView rowTextView = (TextView)getLayoutInflater().inflate(R.layout.yourTextView, null);

This is how I'm using this:

 private List<Tag> tags = new ArrayList<>();

        Gson gson = new Gson();
        Type listType = new TypeToken<List<Tag>>() {
        tags = gson.fromJson(tour.getTagsJSONArray(), listType);

if (flowLayout != null) {
        if(!tags.isEmpty()) {
            Log.e(TAG, "setTags: "+ flowLayout.getChildCount() );
            for (Tag tag : tags) {
                FlowLayout.LayoutParams lparams = new FlowLayout.LayoutParams(FlowLayout.LayoutParams.WRAP_CONTENT, FlowLayout.LayoutParams.WRAP_CONTENT);
                lparams.setMargins(PixelUtil.dpToPx(this, 0), PixelUtil.dpToPx(this, 5), PixelUtil.dpToPx(this, 10), PixelUtil.dpToPx(this, 5));// llp.setMargins(left, top, right, bottom);
                TextView rowTextView = (TextView) getLayoutInflater().inflate(R.layout.tag, null);
        Log.e(TAG, "setTags: after "+ flowLayout.getChildCount() );

And this is my custom TextView named tag:

<?xml version="1.0" encoding="utf-8"?><TextView xmlns:android=""

this is my tag_shape:

<shape xmlns:android=""
<solid android:color="#f2f2f2" />
<corners android:radius="15dp" />


enter image description here

In other place I'm adding textviews with language names from dialog with listview:

enter image description here

enter image description here

Landscape printing from HTML

It's not enough just to rotate the page content. Here is a right CSS which work in the most browsers (Chrome, Firefox, IE9+).

First set body margin to 0, because otherwise page margins will be larger than those you set in the print dialog. Also set background color to visualize pages.

body {
  margin: 0;
  background: #CCCCCC;

margin, border and background are required to visualize pages.

padding must be set to the required print margin. In the print dialog you must set the same margins (10mm in this example).

div.portrait, div.landscape {
  margin: 10px auto;
  padding: 10mm;
  border: solid 1px black;
  overflow: hidden;
  page-break-after: always;
  background: white;

The size of A4 page is 210mm x 297mm. You need to subtract print margins from the size. And set the size of page's content:

div.portrait {
  width: 190mm;
  height: 276mm;
div.landscape {
  width: 276mm;
  height: 190mm;

I use 276mm instead of 277mm, because different browsers scale pages a little bit differently. So some of them will print 277mm-height content on two pages. The second page will be empty. It's more safe to use 276mm.

We don't need any margin, border, padding, background on the printed page, so remove them:

@media print {
  body {
    background: none;
    -ms-zoom: 1.665;
  div.portrait, div.landscape {
    margin: 0;
    padding: 0;
    border: none;
    background: none;
  div.landscape {
    transform: rotate(270deg) translate(-276mm, 0);
    transform-origin: 0 0;

Note that the origin of transformation is 0 0! Also the content of landscape pages must be moved 276mm down!

Also if you have a mix of portrait and lanscape pages IE will zoom out the pages. We fix it by setting -ms-zoom to 1.665. If you'll set it to 1.6666 or something like this the right border of the page content may be cropped sometimes.

If you need IE8- or other old browsers support you can use -webkit-transform, -moz-transform, filter:progid:DXImageTransform.Microsoft.BasicImage(rotation=3). But for modern enough browsers it's not required.

Here is a test page:

    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
      ...Copy all styles here...
    <div class="portrait">A portrait page</div>
    <div class="landscape">A landscape page</div>

How to install libusb in Ubuntu

This should work:

# apt-get install libusb-1.0-0-dev

Unable to start Genymotion Virtual Device - Virtualbox Host Only Ethernet Adapter Failed to start

Just download and install the latest version of Virtual box, run it then run the emulator and viola, it will be up and running. This one worked for me.

Python convert tuple to string

Easiest way would be to use join like this:

>>> myTuple = ['h','e','l','l','o']
>>> ''.join(myTuple)

This works because your delimiter is essentially nothing, not even a blank space: ''.

using stored procedure in entity framework

Simple. Just instantiate your entity, set it to an object and pass it to your view in your controller.

enter image description here


VehicleInfoEntities db = new VehicleInfoEntities();

Stored Procedure



you can add any parameters in your stored procedure inside the brackets ()



public class HomeController : Controller
    VehicleInfoEntities db = new VehicleInfoEntities();

    public ActionResult Index()
        var makes = db.prcGetMakes(null);

        return View(makes);

Saving lists to txt file

@Jon's answer is great and will get you where you need to go. So why is your code printing out what it is. The answer: You're not writing out the contents of your list, but the String representation of your list itself, by an implicit call to Lists.verbList.ToString(). Object.ToString() defines the default behavior you're seeing here.

Update multiple tables in SQL Server using INNER JOIN

You can't update more that one table in a single statement, however the error message you get is because of the aliases, you could try this :


update A
from table1 A inner join table2 B
and A.ORG_ID = @ORG_ID

update B
from table2 B inner join table1 A
    on B.ORG_ID = A.ORG_ID
    and A.ORG_ID = @ORG_ID


Converting a String array into an int Array in java

This is because your string does not strictly contain the integers in string format. It has alphanumeric chars in it.

How to convert a selection to lowercase or uppercase in Sublime Text

For Windows OS

For Uppercase CTRL + K + U

For Lowercase CTRL + K + L

How to obtain values of request variables using Python and Flask

Adding more to Jason's more generalized way of retrieving the POST data or GET data

from flask_restful import reqparse

def parse_arg_from_requests(arg, **kwargs):
    parse = reqparse.RequestParser()
    parse.add_argument(arg, **kwargs)
    args = parse.parse_args()
    return args[arg]

form_field_value = parse_arg_from_requests('FormFieldValue')

How can I split a JavaScript string by white space or comma?

you can use regex in order to catch any length of white space, and this would be like:

var text = "hoi how     are          you";
var arr = text.split(/\s+/);

console.log(arr) // will result : ["hoi", "how", "are", "you"]

console.log(arr[2]) // will result : "are" 

Plugin with id '' not found

Had the same problem.

Fixed by adding the dependency

classpath ''

to the root build.gradle.

source command not found in sh shell

source is a bash built-in command so to execute source command, you can log in as Root.

sudo -s source ./

COLLATION 'utf8_general_ci' is not valid for CHARACTER SET 'latin1'

In my case I created a database and gave the collation 'utf8_general_ci' but the required collation was 'latin1'. After changing my collation type to latin1_bin the error was gone.

Git merge without auto commit

I prefer this way so I don't need to remember any rare parameters.

git merge branch_name

It will then say your branch is ahead by "#" commits, you can now pop these commits off and put them into the working changes with the following:

git reset @~#

For example if after the merge it is 1 commit ahead, use:

git reset @~1

Note: On Windows, quotes are needed. (As Josh noted in comments) eg:

git reset "@~1"

Merging multiple PDFs using iTextSharp in

Code For Merging PDF's in Itextsharp

 public static void Merge(List<String> InFiles, String OutFile)

        using (FileStream stream = new FileStream(OutFile, FileMode.Create))
        using (Document doc = new Document())
        using (PdfCopy pdf = new PdfCopy(doc, stream))

            PdfReader reader = null;
            PdfImportedPage page = null;

            //fixed typo
            InFiles.ForEach(file =>
                reader = new PdfReader(file);

                for (int i = 0; i < reader.NumberOfPages; i++)
                    page = pdf.GetImportedPage(reader, i + 1);


Reliable way to convert a file to a byte[]

Not to repeat what everyone already have said but keep the following cheat sheet handly for File manipulations:

  1. System.IO.File.ReadAllBytes(filename);
  2. File.Exists(filename)
  3. Path.Combine(folderName, resOfThePath);
  4. Path.GetFullPath(path); // converts a relative path to absolute one
  5. Path.GetExtension(path);

Java Replacing multiple different substring in a string at once (or in the most efficient way)

If you are going to be changing a String many times, then it is usually more efficient to use a StringBuilder (but measure your performance to find out):

String str = "The rain in Spain falls mainly on the plain";
StringBuilder sb = new StringBuilder(str);
// do your replacing in sb - although you'll find this trickier than simply using String
String newStr = sb.toString();

Every time you do a replace on a String, a new String object is created, because Strings are immutable. StringBuilder is mutable, that is, it can be changed as much as you want.

HTML table with 100% width, with vertical scroll inside tbody

In following solution, table occupies 100% of the parent container, no absolute sizes required. It's pure CSS, flex layout is used.

Here is how it looks: enter image description here

Possible disadvantages:

  • vertical scrollbar is always visible, regardless of whether it's required;
  • table layout is fixed - columns do not resize according to the content width (you still can set whatever column width you want explicitly);
  • there is one absolute size - the width of the scrollbar, which is about 0.9em for the browsers I was able to check.

HTML (shortened):

<div class="table-container">

CSS, with some decorations omitted for clarity:

.table-container {
    height: 10em;
table {
    display: flex;
    flex-flow: column;
    height: 100%;
    width: 100%;
table thead {
    /* head takes the height it requires, 
    and it's not scaled when table is resized */
    flex: 0 0 auto;
    width: calc(100% - 0.9em);
table tbody {
    /* body takes all the remaining available space */
    flex: 1 1 auto;
    display: block;
    overflow-y: scroll;
table tbody tr {
    width: 100%;
table thead, table tbody tr {
    display: table;
    table-layout: fixed;

full code on jsfiddle

Same code in LESS so you can mix it in:

.table-scrollable() {
  @scrollbar-width: 0.9em;
  display: flex;
  flex-flow: column;

  tbody tr {
    display: table;
    table-layout: fixed;

  thead {
    flex: 0 0 auto;
    width: ~"calc(100% - @{scrollbar-width})";

  tbody {
    display: block;
    flex: 1 1 auto;
    overflow-y: scroll;

    tr {
      width: 100%;

How to style a div to have a background color for the entire width of the content, and not just for the width of the display?

The inline-block display style seems to do what you want. Note that the <nobr> tag is deprecated, and should not be used. Non-breaking white space is doable in CSS. Here's how I would alter your example style rules:

div { display: inline-block; white-space: nowrap; }
.success { background-color: #ccffcc; }

Alter your stylesheet, remove the <nobr> tags from your source, and give it a try. Note that display: inline-block does not work in every browser, though it tends to only be problematic in older browsers (newer versions should support it to some degree). My personal opinion is to ignore coding for broken browsers. If your code is standards compliant, it should work in all of the major, modern browsers. Anyone still using IE6 (or earlier) deserves the pain. :-)

How to pass command line argument to gnuplot?

Yet another way is this:

You have a gnuplot script named

#!/usr/bin/gnuplot -p
# This code is in the file ''
EPATH = $0


Now you can call the gnuplot script by this convoluted peace of syntax:

echo "call \"\" \"'.'\" \"'data.dat'\"" | gnuplot 

Converting a POSTMAN request to Curl

enter image description here

You can see the button "Code" in the attached screenshot, press it and you can get your code in many different languages including PHP cURL

enter image description here

Javac is not found

Start off by opening a cmd.exe session, changing directory to the "program files" directory that has the javac.exe executable and running .\javac.exe.

If that doesn't work, reinstall java. If that works, odds are you will find (in doing that task) that you've installed a 64 bit javac.exe, or a slightly different release number of javac.exe, or in a different drive, etc. and selecting the right entry in your path will become child's play.

Only use the semicolon between directories in the PATH environment variable, and remember that in some systems, you need to log out and log back in before the new environment variable is accessible to all environments.

Disabling Controls in Bootstrap

No, Bootstrap does not introduce special considerations for disabling a drop-down.

<select id="xxx" name="xxx" class="input-medium" disabled>


<select id="xxx" name="xxx" class="input-medium" disabled="disabled">

will work. I prefer to give attributes values (as in the second form; in XHTML, attributes must have a value), but the HTML spec says:

The presence of a boolean attribute on an element represents the true value, and the absence of the attribute represents the false value.


The key differences between read-only and disabled:*

The Disabled attribute

  • Values for disabled form elements are not passed to the processor method. The W3C calls this a successful element.(This works similar to form check boxes that are not checked.)
  • Some browsers may override or provide default styling for disabled form elements. (Gray out or emboss text) Internet Explorer 5.5 is particularly nasty about this.
  • Disabled form elements do not receive focus.
  • Disabled form elements are skipped in tabbing navigation.

The Read Only Attribute

  • Not all form elements have a readonly attribute. Most notable, the <SELECT>, <OPTION>, and <BUTTON> elements do not have readonly attributes (although thy both have disabled attributes)
  • Browsers provide no default overridden visual feedback that the form element is read only
  • Form elements with the readonly attribute set will get passed to the form processor.
  • Read only form elements can receive the focus
  • Read only form elements are included in tabbed navigation.

*-blatant plagiarism from

How can I use regex to get all the characters after a specific character, e.g. comma (",")

Another idea is to do myVar.split(',')[1];

For simple case, not using a regexp is a good idea...

Matplotlib-Animation "No MovieWriters Available"

If you are using Ubuntu 14.04 ffmpeg is not available. You can install it by using the instructions directly from

In short you will have to:

sudo add-apt-repository ppa:mc3man/trusty-media
sudo apt-get update
sudo apt-get install ffmpeg gstreamer0.10-ffmpeg

If this does not work maybe try using sudo apt-get dist-upgrade but this may broke things in your system.

Convert HTML to PDF in .NET

Try this PDF Duo .Net converting component for converting HTML to PDF from ASP.NET application without using additional dlls.

You can pass the HTML string or file, or stream to generate the PDF. Use the code below (Example C#):

string file_html = @"K:\hdoc.html";   
string file_pdf = @"K:\new.pdf";   
    DuoDimension.HtmlToPdf conv = new DuoDimension.HtmlToPdf();   
    textBox4.Text = "C# Example: Converting succeeded";   

Info + C#/VB examples you can find at:

How to create a function in SQL Server

I can give a small hack, you can use T-SQL function. Try this:

FROM dbo.YourTable .....

Your password does not satisfy the current policy requirements

didn't work for me on ubuntu fresh install of mysqld, had to add this: to /etc/mysql/mysql.conf.d/mysqld.cnf or the server wouldn't start (guess the plugin didn't load at the right time when I simply added it without the plugin-load-add directive)

spark submit add multiple jars in classpath

You can use * for import all jars into a folder when adding in conf/spark-defaults.conf .

spark.driver.extraClassPath /fullpath/*
spark.executor.extraClassPath /fullpath/*

Does Internet Explorer 8 support HTML 5?

IE8 beta 2 supports two APIs from HTML5: cross-document messaging and non-SQL storage.

IE8 beta 2 doesn’t implement the HTML5 parsing algorithm or the new elements (no <canvas> or <video> support).

There are also bug fixes that align IE8 better with HTML5.

How can I access each element of a pair in a pair list?

I don't think that you'll like it but I made a pair port for python :) using it is some how similar to c++

pair = Pair
pair.make_pair(value1, value2)


pair = Pair(value1, value2)

here's the source code pair_stl_for_python

What is the difference between "#!/usr/bin/env bash" and "#!/usr/bin/bash"?

Instead of explicitly defining the path to the interpreter as in /usr/bin/bash/, by using the env command, the interpreter is searched for and launched from wherever it is first found. This has both upsides and downsides

How do you rotate a two dimensional array?

It is not possible to do it quicker than O(n^2) for in place rotation, for the reason that if we want to rotate the matrix, we have to touch all the n^2 element at least once, no matter what algorithm you are implementing.

how to prevent css inherit

Using the wildcard * selector in CSS to override inheritance for all attributes of an element (by setting these back to their initial state).

An example of its use:

li * {
   display: initial;

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

for (int j = dataGridView1.Rows.Count; j > 0 ; j--)
    if (dataGridView1.Rows[j-1].Selected)

Xcopy Command excluding files and folders

Just give full path to exclusion file: eg..

-- no - - - - -xcopy c:\t1 c:\t2 /EXCLUDE:list-of-excluded-files.txt

correct - - - xcopy c:\t1 c:\t2 /EXCLUDE:C:\list-of-excluded-files.txt

In this example the file would be located " C:\list-of-excluded-files.txt "


correct - - - xcopy c:\t1 c:\t2 /EXCLUDE:C:\mybatch\list-of-excluded-files.txt

In this example the file would be located " C:\mybatch\list-of-excluded-files.txt "

Full path fixes syntax error.

How can I mock requests and the response?

Try using the responses library. Here is an example from their documentation:

import responses
import requests

def test_simple():
    responses.add(responses.GET, '',
                  json={'error': 'not found'}, status=404)

    resp = requests.get('')

    assert resp.json() == {"error": "not found"}

    assert len(responses.calls) == 1
    assert responses.calls[0].request.url == ''
    assert responses.calls[0].response.text == '{"error": "not found"}'

It provides quite a nice convenience over setting up all the mocking yourself.

There's also HTTPretty:

It's not specific to requests library, more powerful in some ways though I found it doesn't lend itself so well to inspecting the requests that it intercepted, which responses does quite easily

There's also httmock.

How to verify a method is called two times with mockito verify()

build gradle:

testImplementation "com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0"


interface MyCallback {
  fun someMethod(value: String)

class MyTestableManager(private val callback: MyCallback){
  fun perform(){


import com.nhaarman.mockitokotlin2.times
import com.nhaarman.mockitokotlin2.verify
import com.nhaarman.mockitokotlin2.mock
val callback: MyCallback = mock()
val manager = MyTestableManager(callback)

val captor: KArgumentCaptor<String> = com.nhaarman.mockitokotlin2.argumentCaptor<String>()

verify(callback, times(3)).someMethod(captor.capture())

assertTrue(captor.allValues[0] == "first")
assertTrue(captor.allValues[1] == "second")
assertTrue(captor.allValues[2] == "third")

How to declare a global variable in React?

Can keep global variables in webpack i.e. in webpack.config.js

externals: {
  'config': JSON.stringify(GLOBAL_VARIABLE: "global var value")

In js module can read like

var config = require('config')

Hope this will help.

Peak-finding algorithm for Python/SciPy

The function scipy.signal.find_peaks, as its name suggests, is useful for this. But it's important to understand well its parameters width, threshold, distance and above all prominence to get a good peak extraction.

According to my tests and the documentation, the concept of prominence is "the useful concept" to keep the good peaks, and discard the noisy peaks.

What is (topographic) prominence? It is "the minimum height necessary to descend to get from the summit to any higher terrain", as it can be seen here:

enter image description here

The idea is:

The higher the prominence, the more "important" the peak is.


enter image description here

I used a (noisy) frequency-varying sinusoid on purpose because it shows many difficulties. We can see that the width parameter is not very useful here because if you set a minimum width too high, then it won't be able to track very close peaks in the high frequency part. If you set width too low, you would have many unwanted peaks in the left part of the signal. Same problem with distance. threshold only compares with the direct neighbours, which is not useful here. prominence is the one that gives the best solution. Note that you can combine many of these parameters!


import numpy as np
import matplotlib.pyplot as plt 
from scipy.signal import find_peaks

x = np.sin(2*np.pi*(2**np.linspace(2,10,1000))*np.arange(1000)/48000) + np.random.normal(0, 1, 1000) * 0.15
peaks, _ = find_peaks(x, distance=20)
peaks2, _ = find_peaks(x, prominence=1)      # BEST!
peaks3, _ = find_peaks(x, width=20)
peaks4, _ = find_peaks(x, threshold=0.4)     # Required vertical distance to its direct neighbouring samples, pretty useless
plt.subplot(2, 2, 1)
plt.plot(peaks, x[peaks], "xr"); plt.plot(x); plt.legend(['distance'])
plt.subplot(2, 2, 2)
plt.plot(peaks2, x[peaks2], "ob"); plt.plot(x); plt.legend(['prominence'])
plt.subplot(2, 2, 3)
plt.plot(peaks3, x[peaks3], "vg"); plt.plot(x); plt.legend(['width'])
plt.subplot(2, 2, 4)
plt.plot(peaks4, x[peaks4], "xk"); plt.plot(x); plt.legend(['threshold'])

How to load Spring Application Context

package com.dataload;

    public class insertCSV 
        public static void main(String args[])
            ApplicationContext context =
        new ClassPathXmlApplicationContext("applicationcontext.xml");

            // retrieve configured instance
            JobLauncher launcher = context.getBean("laucher", JobLauncher.class);
            Job job = context.getBean("job", Job.class);
            JobParameters jobParameters = context.getBean("jobParameters", JobParameters.class);

How to outline text in HTML / CSS

With HTML5's support for svg, you don't need to rely on shadow hacks.

<svg  width="100%" viewBox="0 0 600 100">_x000D_
<text x=0 y=20 font-size=12pt fill=white stroke=black stroke-width=0.75>_x000D_
    This text exposes its vector representation, _x000D_
    making it easy to style shape-wise without hacks. _x000D_
    HTML5 supports it, so no browser issues. Only downside _x000D_
    is that svg has its own quirks and learning curve _x000D_
    (c.f. bounding box issue/no typesetting by default)_x000D_

Resize image proportionally with CSS?

    object-fit: scale-down;

works for me. It scales down larger images to fit in the box, but leaves smaller images their original size.

split string in two on given index and return both parts

function splitText(value, index) {
  if (value.length < index) {return value;} 
  return [value.substring(0, index)].concat(splitText(value.substring(index), index));
console.log(splitText('this is a testing peace of text',10));
// ["this is a ", "testing pe", "ace of tex", "t"] 

For those who want to split a text into array using the index.

How to reset or change the passphrase for a GitHub SSH key?

In short there's no way to recover the passphrase for a pair of SSH keys. Why? Because it was intended this way in the first place for security reasons. The answers the other people gave you are all correct ways to CHANGE the password of your keys, not to recover them. So if you've forgotten your passphrase, the best you can do is create a new pair of SSH keys. Here's how to generate SSH keys and add it to your GitHub account.

Dynamically updating plot in matplotlib

Here is a way which allows to remove points after a certain number of points plotted:

import matplotlib.pyplot as plt
# generate axes object
ax = plt.axes()

# set limits

for i in range(10):        
     # add something to axes    
     ax.scatter([i], [i]) 
     ax.plot([i], [i+1], 'rx')

     # draw the plot
     plt.pause(0.01) #is necessary for the plot to update for some reason

     # start removing points if you don't want all shown
     if i>2:

How to randomize two ArrayLists in the same fashion?

The simplest approach is to encapsulate the two values together into a type which has both the image and the file. Then build an ArrayList of that and shuffle it.

That improves encapsulation as well, giving you the property that you'll always have the same number of files as images automatically.

An alternative if you really don't like that idea would be to write the shuffle code yourself (there are plenty of examples of a modified Fisher-Yates shuffle in Java, including several on Stack Overflow I suspect) and just operate on both lists at the same time. But I'd strongly recommend going with the "improve encapsulation" approach.

How should I pass multiple parameters to an ASP.Net Web API GET?

I just had to implement a RESTfull api where I need to pass parameters. I did this by passing the parameters in the query string in the same style as described by Mark's first example "api/controller?start=date1&end=date2"

In the controller I used a tip from URL split in C#?

// uri: /api/courses
public IEnumerable<Course> Get()
    NameValueCollection nvc = HttpUtility.ParseQueryString(Request.RequestUri.Query);
    var system = nvc["System"];
    // BL comes here
    return _courses;

In my case I was calling the WebApi via Ajax looking like:

        url: '/api/DbMetaData',
        type: 'GET',
        data: { system : 'My System',
                searchString: '123' },
        dataType: 'json',
        success: function (data) {
                  $.each(data, function (index, v) {
                  alert(index + ': ' +;
         statusCode: {
                  404: function () {

I hope this helps...

MySQL Error 1215: Cannot add foreign key constraint

This is a subtle version of what has already been said, but in my instance, I had 2 databases (foo and bar). I created foo first and I didn't realize it referenced a foreign key in bar.baz (which wasn't created yet). When I tried to create bar.baz (without any foreign keys), I kept getting this error. After looking around for a while I found the foreign key in foo.

So, long story short, If you get this error, you may have a pre-existing foreign key to the table being created.

Checking if a file is a directory or just a file

Use the S_ISDIRmacro:

int isDirectory(const char *path) {
   struct stat statbuf;
   if (stat(path, &statbuf) != 0)
       return 0;
   return S_ISDIR(statbuf.st_mode);

How to format a QString?

You can use QString.arg like this

QString my_formatted_string = QString("%1/%2-%3.txt").arg("~", "Tom", "Jane");
// You get "~/Tom-Jane.txt"

This method is preferred over sprintf because:

Changing the position of the string without having to change the ordering of substitution, e.g.

// To get "~/Jane-Tom.txt"
QString my_formatted_string = QString("%1/%3-%2.txt").arg("~", "Tom", "Jane");

Or, changing the type of the arguments doesn't require changing the format string, e.g.

// To get "~/Tom-1.txt"
QString my_formatted_string = QString("%1/%2-%3.txt").arg("~", "Tom", QString::number(1));

As you can see, the change is minimal. Of course, you generally do not need to care about the type that is passed into QString::arg() since most types are correctly overloaded.

One drawback though: QString::arg() doesn't handle std::string. You will need to call: QString::fromStdString() on your std::string to make it into a QString before passing it to QString::arg(). Try to separate the classes that use QString from the classes that use std::string. Or if you can, switch to QString altogether.

UPDATE: Examples are updated thanks to Frank Osterfeld.

UPDATE: Examples are updated thanks to alexisdm.

How can I set multiple CSS styles in JavaScript?

This is old thread, so I figured for anyone looking for a modern answer, I would suggest using Object.keys();

var myDiv = document.getElementById("myDiv");
var css = {
    "font-size": "14px",
    "color": "#447",
    "font-family": "Arial",
    "text-decoration": "underline"

function applyInlineStyles(obj) {
    var result = "";
    Object.keys(obj).forEach(function (prop) {
        result += prop + ": " + obj[prop] + "; ";
    return result;
} = applyInlineStyles(css);

Need a query that returns every field that contains a specified letter

where somefield like '%a%' or somefield like '%b%'

Is it possible to get a list of files under a directory of a website? How?

Yes, you can, but you need a few tools first. You need to know a little about basic coding, FTP clients, port scanners and brute force tools, if it has a .htaccess file.

If not just try tgp.linkurl.htm or html, ie default.html, www/home/siteurl/web/, or wap /index/ default /includes/ main/ files/ images/ pics/ vids/, could be possible file locations on the server, so try all of them so www/home/siteurl/web/includes/.htaccess or default.html. You'll hit a file after a few tries then work off that. Yahoo has a site file viewer too: you can try to scan sites file indexes.

Alternatively, try brutus aet, trin00, trinity.x, or whiteshark airtool to crack the site's FTP login (but it's illegal and I do not condone that).

How to get current date in 'YYYY-MM-DD' format in ASP.NET?

Might be worthwhile using the CultureInfo to apply DateTime formatting throughout the website. Insteado f running around formatting whever you have to.

CultureInfo.CurrentUICulture.DateTimeFormat.SetAllDateTimePatterns( ...


CultureInfo.CurrentUICulture.DateTimeFormat.ShortDatePattern = "yyyy-MM-dd"; 

Code should go somewhere in your Global.asax file

protected void Application_Start(){ ...

htaccess <Directory> deny from all

You cannot use the Directory directive in .htaccess. However if you create a .htaccess file in the /system directory and place the following in it, you will get the same result

#place this in /system/.htaccess as you had before
deny from all

Can a table have two foreign keys?

userName VARCHAR(100) NOT NULL,
password VARCHAR(255) NOT NULL,
email VARCHAR(255) NOT NULL,
Favorite VARCHAR(255) NOT NULL,
PRIMARY KEY (user_id)


    PRIMARY KEY (EventID),
    EventName VARCHAR(100) NOT NULL,
    EventLocation VARCHAR(100) NOT NULL,
    EventPriceRange VARCHAR(100) NOT NULL,
    EventDate Date NOT NULL,
    EventTime Time NOT NULL,
    EventDescription VARCHAR(255) NOT NULL,
    EventCategory VARCHAR(255) NOT NULL,
    EventImage  LONGBLOB NOT NULL,     
    FOREIGN KEY (EventID) REFERENCES User(user_id)

Python: pandas merge multiple dataframes

Look at this pandas three-way joining multiple dataframes on columns

filenames = ['fn1', 'fn2', 'fn3', 'fn4',....]
dfs = [pd.read_csv(filename, index_col=index_col) for filename in filenames)]

How to attach source or JavaDoc in eclipse for any jar file e.g. JavaFX?

Alternatively you can also,

1) Navigate to that method by Ctrl+Click on the method. The new tab/window will opened with text "Source not found" and button "Attach Source.." in it
2) Click the button "Attach Source.."
3) New window pops up. Click the button "External Folder"
4) Locate the JavaFX javadoc folder. If you are on Windows with default installation settings, then the folder path is C:\Program Files\Oracle\JavaFX 2.0 SDK\docs

How to decode encrypted wordpress admin password?

just edit wp_user table with your phpmyadmin, and choose MD5 on Function field then input your new password, save it (go button). enter image description here

How to set css style to button?

You can assign a class to your ASP.NET Button and then apply the desired style to it.

<asp:Button class="mybtn" Text="Button" runat="server"></asp:Button>


   border:1px solid Red;
   //some more styles

How to get current instance name from T-SQL

How about this:

EXECUTE xp_regread @rootkey='HKEY_LOCAL_MACHINE',
                   @key='SOFTWARE\Microsoft\Microsoft SQL Server\Instance Names\SQl',

This will get the instance name as well. null means default instance:


cor shows only NA or 1 for correlations - Why?

The 1s are because everything is perfectly correlated with itself, and the NAs are because there are NAs in your variables.

You will have to specify how you want R to compute the correlation when there are missing values, because the default is to only compute a coefficient with complete information.

You can change this behavior with the use argument to cor, see ?cor for details.

How do I run a node.js app as a background service?

use nssm the best solution for windows, just download nssm, open cmd to nssm directory and type

nssm install <service name> <node path> <app.js path> 

eg: nssm install myservice "C:\Program Files\nodejs" "C:\myapp\app.js" 

this will install a new windows service which will be listed at services.msc from there you can start or stop the service, this service will auto start and you can configure to restart if it fails.

How can I start InternetExplorerDriver using Selenium WebDriver

1---Enable protected mode for all zones You need to enable protected mode for all zones from Internet Options -> Security tab. To enable protected mode for all zones

Open Internet Explorer browser.
Go to menu Tools -> Internet Options.
Click on Security tab.
Select Internet from "Select a zone to view or change security settings" and Select(check) check box "Enable Protected Mode" from In the "Security level for this zone" block .
Apply same thing for all other 3 zones -> Local Internet, Trusted Sites and Restricted Sites

This setting will resolve error related to "Protected Mode settings are not the same for all zones.

2-- Set IE browser's zoom level 100%

Open Internet Explorer browser.
Go to menu View -> Zoom -> Select 100%

WAMP/XAMPP is responding very slow over localhost

I had this problem too.

I added the entries suggested above but it failed to work.

It was due to the fact Spybot Search and Destroy had added 15,000 lines of immunized site (ie prevents you from visiting them) to my hosts file.

My hosts file was 433k - I removed those lines and my page load speed improved immensely.

How to take a first character from the string

"ABCDEFG".First returns "A"

Dim s as string

s = "Rajan"

s = "Sajan"

How to open a PDF file in an <iframe>?

This is the code to link an HTTP(S) accessible PDF from an <iframe>:

<iframe src=""
   width="800" height="600">


EDIT: and you can use Javascript, from the <a> tag (onclick event) to set iFrame' SRC attribute at run-time...

EDIT 2: Apparently, it is a bug (but there are workarounds):

PDF files do not open in Internet Explorer with Adobe Reader 10.0 - users get an empty gray screen. How can I fix this for my users?

How do you enable mod_rewrite on any OS?

In order to use mod_rewrite you can type the following command in the terminal:

 $ su

 $ passwd **********

 # a2enmod rewrite

Restart apache2 after

 # service apache2 restart

 # /etc/init.d/apache2 restart


 # service apache2 restart

npm ERR! registry error parsing json - While trying to install Cordova for Ionic Framework in Windows 8

I had the same issue and the following fixed my issue:

  1. Set the registry: npm config set registry ""
  2. Removed the entry in hosts file (using Windows 7) => C:\Windows\System32\drivers\etc\hosts

Setting a system environment variable from a Windows batch file?

Simple example for how to set JAVA_HOME with setx.exe in command line:

setx JAVA_HOME "C:\Program Files (x86)\Java\jdk1.7.0_04"

This will set environment variable "JAVA_HOME" for current user. If you want to set a variable for all users, you have to use option "-m". Here is an example:

setx -m JAVA_HOME "C:\Program Files (x86)\Java\jdk1.7.0_04"

Note: you have to execute this command as Administrator.

Note: Make sure to run the command setx from an command-line Admin window

Get item in the list in Scala?

Please use parenthesis () to access the list elements list_name(index)

How can I center text (horizontally and vertically) inside a div block?


.center {
    display: grid;
    justify-items: center;
    align-items: center;

.center {_x000D_
    display: grid;_x000D_
    justify-items: center;_x000D_
    align-items: center;_x000D_
.box {_x000D_
    width: 200px;_x000D_
    height: 100px;_x000D_
    background: red;_x000D_
<div class="box center">My text</div>

How do I perform a Perl substitution on a string while keeping the original?

The statement:

(my $newstring = $oldstring) =~ s/foo/bar/g;

Which is equivalent to:

my $newstring = $oldstring;
$newstring =~ s/foo/bar/g;

Alternatively, as of Perl 5.13.2 you can use /r to do a non destructive substitution:

use 5.013;
my $newstring = $oldstring =~ s/foo/bar/gr;

How to grep for two words existing on the same line?

git grep

Here is the syntax using git grep combining multiple patterns using Boolean expressions:

git grep -e pattern1 --and -e pattern2 --and -e pattern3

The above command will print lines matching all the patterns at once.

If the files aren't under version control, add --no-index param.

Search files in the current directory that is not managed by Git.

Check man git-grep for help.

See also:

What does "ulimit -s unlimited" do?

ulimit -s unlimited lets the stack grow unlimited.

This may prevent your program from crashing if you write programs by recursion, especially if your programs are not tail recursive (compilers can "optimize" those), and the depth of recursion is large.

Python Threading String Arguments

from threading import Thread
from time import sleep
def run(name):
    for x in range(10):
        print("helo "+name)
def run1():
    for x in range(10):

How to cache data in a MVC application

You can also try and use the caching built into ASP MVC:

Add the following attribute to the controller method you'd like to cache:


In this case the ActionResult of this will be cached for 10 seconds.

More on this here

How to set Internet options for Android emulator?

By default, you should be able to toggle the Internet access to your emulator with F8 (on Windows) and Fn + F8 (on Mac OS X) - I think F8 also works for Linux, but I'm not 100% sure.

With this shortcut, you get the ACTION_BACKGROUND_DATA_SETTING_CHANGED dispatched.

Hope that helps.

Difference between StringBuilder and StringBuffer

  • StringBuffer is thread-safe but StringBuilder is not thread safe.
  • StringBuilder is faster than StringBuffer.
  • StringBuffer is synchronized whereas StringBuilder is not synchronized.

Angular Directive refresh on parameter change

Link function only gets called once, so it would not directly do what you are expecting. You need to use angular $watch to watch a model variable.

This watch needs to be setup in the link function.

If you use isolated scope for directive then the scope would be

scope :{typeId:'@' }

In your link function then you add a watch like

link: function(scope, element, attrs) {
    scope.$watch("typeId",function(newValue,oldValue) {
        //This gets called when data changes.

If you are not using isolated scope use watch on some_prop

Convert Iterable to Stream using Java 8 JDK

I've created this class:

public class Streams {
     * Converts Iterable to stream
    public static <T> Stream<T>  streamOf(final Iterable<T> iterable) {
        return toStream(iterable, false);

     * Converts Iterable to parallel stream
    public static <T> Stream<T> parallelStreamOf(final Iterable<T> iterable) {
        return toStream(iterable, true);

    private static <T> Stream<T> toStream(final Iterable<T> iterable, final boolean isParallel) {
        return, isParallel);

I think it's perfectly readable because you don't have to think about spliterators and booleans (isParallel).

How to read lines of a file in Ruby

Don't forget that if you are concerned about reading in a file that might have huge lines that could swamp your RAM during runtime, you can always read the file piece-meal. See "Why slurping a file is bad".'file_path', 'rb') do |io|
  while chunk = * 1024) do
    something_with_the chunk
    # like stream it across a network
    # or write it to another file:
    # other_io.write chunk

Apply style to parent if it has child with css

It's not possible with CSS3. There is a proposed CSS4 selector, $, to do just that, which could look like this (Selecting the li element):

ul $li ul.sub { ... }

See the list of CSS4 Selectors here.

As an alternative, with jQuery, a one-liner you could make use of would be this:

$('ul li:has(ul.sub)').addClass('has_sub');

You could then go ahead and style the li.has_sub in your CSS.

How to disable gradle 'offline mode' in android studio?

Edit. As noted in the comments, this is no longer working with the latest Android Studio releases.

The latest Android studio seems to only reference to "Offline mode" via the keymap, but toggling this does not seem to change anything anymore.

In Android Studio open the settings and search for offline it will find the Gradle category which contains Offline work. You can disable it there.

Gradle Offline work

React: why child component doesn't update when prop changes

I had the same problem. This is my solution, I'm not sure that is the good practice, tell me if not:

state = {
  value: this.props.value

componentDidUpdate(prevProps) {
  if(prevProps.value !== this.props.value) {
    this.setState({value: this.props.value});

UPD: Now you can do the same thing using React Hooks: (only if component is a function)

const [value, setValue] = useState(propName);
// This will launch only if propName value has chaged.
useEffect(() => { setValue(propName) }, [propName]);

Declaring variable workbook / Worksheet vba

I had the same issue. I used Worksheet instead of Worksheets and it was resolved. Not sure what the difference is between them.

How to create a XML object from String in Java?

If you can create a string xml you can easily transform it to the xml document object e.g. -

String xmlString = "<?xml version=\"1.0\" encoding=\"utf-8\"?><a><b></b><c></c></a>";  

DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();  
DocumentBuilder builder;  
try {  
    builder = factory.newDocumentBuilder();  
    Document document = builder.parse(new InputSource(new StringReader(xmlString)));  
} catch (Exception e) {  

You can use the document object and xml parsing libraries or xpath to get back the ip address.

nginx showing blank PHP pages

If you getting a blank screen, that may be because of 2 reasons:

  1. Browser blocking the Frames from being displayed. In some browsers the frames are considered as unsafe. To overcome this you can launch the frameless version of phpPgAdmin by


  2. You have enabled a security feature in Nginx for X-Frame-Options try disabling it.

Extracting substrings in Go

8 years later I stumbled upon this gem, and yet I don't believe OP's original question was really answered:

so I came up with the following code to trim the newline character

While the bufio.Reader type supports a ReadLine() method which both removes \r\n and \n it is meant as a low-level function which is awkward to use because repeated checks are necessary.

IMO an idiomatic way to remove whitespace is to use Golang's strings library:

input, _ = src.ReadString('\n')

// more specific to the problem of trailing newlines
actual = strings.TrimRight(input, "\r\n")

// or if you don't mind to trim leading and trailing whitespaces 
actual := strings.TrimSpace(input)

See this example in action in the Golang playground:

How to specify an element after which to wrap in css flexbox?

There is part of the spec that sure sounds like this... right in the "flex layout algorithm" and "main sizing" sections:

Otherwise, starting from the first uncollected item, collect consecutive items one by one until the first time that the next collected item would not fit into the flex container’s inner main size, or until a forced break is encountered. If the very first uncollected item wouldn’t fit, collect just it into the line. A break is forced wherever the CSS2.1 page-break-before/page-break-after [CSS21] or the CSS3 break-before/break-after [CSS3-BREAK] properties specify a fragmentation break.


It sure sounds like (aside from the fact that page-breaks ought to be for printing), when laying out a potentially multi-line flex layout (which I take from another portion of the spec is one without flex-wrap: nowrap) a page-break-after: always or break-after: always should cause a break, or wrap to the next line.

.flex-container {
  display: flex;
  flex-flow: row wrap;

.child {
  flex-grow: 1;

.child.break-here {
  page-break-after: always;
  break-after: always;

However, I have tried this and it hasn't been implemented that way in...

  • Safari (up to 7)
  • Chrome (up to 43 dev)
  • Opera (up to 28 dev & 12.16)
  • IE (up to 11)

It does work the way it sounds (to me, at least) like in:

  • Firefox (28+)

Sample at

I didn't find any other requests in the bug tracker, so I reported it at

But the topic took to the mailing list and, regardless of how it sounds, that's not what apparently they meant to imply, except I guess for pagination. So there's no way to wrap before or after a particular box in flex layout without nesting successive flex layouts inside flex children or fiddling with specific widths (e.g. flex-basis: 100%).

This is deeply annoying, of course, since working with the Firefox implementation confirms my suspicion that the functionality is incredibly useful. Aside from the improved vertical alignment, the lack obviates a good deal of the utility of flex layout in numerous scenarios. Having to add additional wrapping tags with nested flex layouts to control the point at which a row wraps increases the complexity of both the HTML and CSS and, sadly, frequently renders order useless. Similarly, forcing the width of an item to 100% reduces the "responsive" potential of the flex layout or requires a lot of highly specific queries or count selectors (e.g. the techniques that may accomplish the general result you need that are mentioned in the other answers).

At least floats had clear. Something may get added at some point or another for this, one hopes.

LINQ orderby on date field in descending order

I was trying to also sort by a DateTime field descending and this seems to do the trick:

var ud = (from d in env 
     orderby -d.ReportDate.Ticks                 
     select  d.ReportDate.ToString("yyyy-MMM") ).Distinct(); 

static linking only some libraries

There is also -l:libstatic1.a (minus l colon) variant of -l option in gcc which can be used to link static library (Thanks to Is it documented? Not in the official documentation of gcc (which is not exact for shared libs too):

-l library 

Search the library named library when linking. (The second alternative with the library as a separate argument is only for POSIX compliance and is not recommended.) ... The only difference between using an -l option and specifying a file name is that -l surrounds library with ‘lib’ and ‘.a’ and searches several directories.

The binutils ld doc describes it. The -lname option will do search for then for libname.a adding lib prefix and .so (if enabled at the moment) or .a suffix. But -l:name option will only search exactly for the name specified:

-l namespec

Add the archive or object file specified by namespec to the list of files to link. This option may be used any number of times. If namespec is of the form :filename, ld will search the library path for a file called filename, otherwise it will search the library path for a file called libnamespec.a.

On systems which support shared libraries, ld may also search for files other than libnamespec.a. Specifically, on ELF and SunOS systems, ld will search a directory for a library called before searching for one called libnamespec.a. (By convention, a .so extension indicates a shared library.) Note that this behavior does not apply to :filename, which always specifies a file called filename.

The linker will search an archive only once, at the location where it is specified on the command line. If the archive defines a symbol which was undefined in some object which appeared before the archive on the command line, the linker will include the appropriate file(s) from the archive. However, an undefined symbol in an object appearing later on the command line will not cause the linker to search the archive again.

See the -( option for a way to force the linker to search archives multiple times.

You may list the same archive multiple times on the command line.

This type of archive searching is standard for Unix linkers. However, if you are using ld on AIX, note that it is different from the behaviour of the AIX linker.

The variant -l:namespec is documented since 2.18 version of binutils (2007):

C++ catching all exceptions

it is not possible (in C++) to catch all exceptions in a portable manner. This is because some exceptions are not exceptions in a C++ context. This includes things like division by zero errors and others. It is possible to hack about and thus get the ability to throw exceptions when these errors happen, but it's not easy to do and certainly not easy to get right in a portable manner.

If you want to catch all STL exceptions, you can do

try { ... } catch( const std::exception &e) { ... }

Which will allow you do use e.what(), which will return a const char*, which can tell you more about the exception itself. This is the construct that resembles the Java construct, you asked about, the most.

This will not help you if someone is stupid enough to throw an exception that does not inherit from std::exception.

Check for special characters in string

var specialChars = "<>@!#$%^&*()_+[]{}?:;|'\"\\,./~`-=";_x000D_
var checkForSpecialChar = function(string){_x000D_
 for(i = 0; i < specialChars.length;i++){_x000D_
   if(string.indexOf(specialChars[i]) > -1){_x000D_
       return true_x000D_
 return false;_x000D_
var str = "YourText";_x000D_
  alert("Not Valid");_x000D_
} else {_x000D_

Node update a specific package

Always you can do it manually. Those are the steps:

  • Go to the NPM package page, and search for the GitHub link.
  • Now download the latest version using GitHub download link, or by clonning. git clone github_url
  • Copy the package to your node_modules folder for e.g. node_modules/browser-sync

Now it should work for you. To be sure it will not break in the future when you do npm i, continue the upcoming two steps:

  • Check the version of the new package by reading the package.json file in it's folder.
  • Open your project package.json and set the same version for where it's appear in the dependencies part of your package.json

While it's not recommened to do it manually. Sometimes it's good to understand how things are working under the hood, to be able to fix things. I found myself doing it from time to time.

Create a Dropdown List for MVC3 using Entity Framework (.edmx Model) & Razor Views && Insert A Database Record to Multiple Tables

Don't pass db models directly to your views. You're lucky enough to be using MVC, so encapsulate using view models.

Create a view model class like this:

public class EmployeeAddViewModel
    public Employee employee { get; set; }
    public Dictionary<int, string> staffTypes { get; set; }
    // really? a 1-to-many for genders
    public Dictionary<int, string> genderTypes { get; set; }

    public EmployeeAddViewModel() { }
    public EmployeeAddViewModel(int id)
        employee = someEntityContext.Employees
            .Where(e => e.ID == id).SingleOrDefault();

        // instantiate your dictionaries

        foreach(var staffType in someEntityContext.StaffTypes)
            staffTypes.Add(staffType.ID, staffType.Type);

        // repeat similar loop for gender types


public ActionResult Add()
    return View(new EmployeeAddViewModel());

public ActionResult Add(EmployeeAddViewModel vm)
        return View("Index"); // or wherever you go after successful add

    return View(vm);

Then, finally in your view (which you can use Visual Studio to scaffold it first), change the inherited type to ShadowVenue.Models.EmployeeAddViewModel. Also, where the drop down lists go, use:

@Html.DropDownListFor(model => model.employee.staffTypeID,
    new SelectList(model.staffTypes, "ID", "Type"))

and similarly for the gender dropdown

@Html.DropDownListFor(model => model.employee.genderID,
    new SelectList(model.genderTypes, "ID", "Gender"))

Update per comments

For gender, you could also do this if you can be without the genderTypes in the above suggested view model (though, on second thought, maybe I'd generate this server side in the view model as IEnumerable). So, in place of new SelectList... below, you would use your IEnumerable.

@Html.DropDownListFor(model => model.employee.genderID,
    new SelectList(new SelectList()
        new { ID = 1, Gender = "Male" },
        new { ID = 2, Gender = "Female" }
    }, "ID", "Gender"))

Finally, another option is a Lookup table. Basically, you keep key-value pairs associated with a Lookup type. One example of a type may be gender, while another may be State, etc. I like to structure mine like this:

ID | LookupType | LookupKey | LookupValue | LookupDescription | Active
1  | Gender     | 1         | Male        | male gender       | 1
2  | State      | 50        | Hawaii      | 50th state        | 1
3  | Gender     | 2         | Female      | female gender     | 1
4  | State      | 49        | Alaska      | 49th state        | 1
5  | OrderType  | 1         | Web         | online order      | 1

I like to use these tables when a set of data doesn't change very often, but still needs to be enumerated from time to time.

Hope this helps!

Batch file to copy files from one folder to another folder

You can use esentutl to copy (mainly big) files with a progress bar:

esentutl /y "my.file" /d "another.file" /o

the progress bar looks like this:

enter image description here

How to list all methods for an object in Ruby?

If You are looking list of methods which respond by an instance (in your case @current_user). According to ruby documentation methods

Returns a list of the names of public and protected methods of obj. This will include all the methods accessible in obj's ancestors. If the optional parameter is false, it returns an array of obj's public and protected singleton methods, the array will not include methods in modules included in obj.

@current_user.methods(false) #only public and protected singleton methods and also array will not include methods in modules included in @current_user class or parent of it.

Alternatively, You can also check that a method is callable on an object or not?.


If you don't want parent class methods then just subtract the parent class methods from it.

@current_user.methods - #methods that are available to @current_user instance.

iOS 8 removed "minimal-ui" viewport property, are there other "soft fullscreen" solutions?

It IS possible, using something like the below example that I put together with the help of work from ( that didn't quite work on iOS 11:

Here's the modified code that works on iOS 11.03, please comment if it worked for you.

The key is adding some size to BODY so the browser can scroll, ex: height: calc(100% + 40px);

Full sample below & link to view in your browser (please test!)

<html lang="en">
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CodeHots iOS WebApp Minimal UI via Scroll Test</title>

        html, body {
            height: 100%;
        html {
            background-color: red;
        body {
            background-color: blue;
            /* important to allow page to scroll */
            height: calc(100% + 40px);
            margin: 0;
        div.header {
            width: 100%;
            height: 40px;
            background-color: green;
            overflow: hidden;
        div.content {
            height: 100%;
            height: calc(100% - 40px);
            width: 100%;
            background-color: purple;
            overflow: hidden;
        div.cover {
            position: absolute;
            top: 0;
            left: 0;
            z-index: 100;
            width: 100%;
            height: 100%;
            overflow: hidden;
            background-color: rgba(0, 0, 0, 0.5);
            color: #fff;
            display: none;
        @media screen and (width: 320px) {
            html {
                height: calc(100% + 72px);
            div.cover {
                display: block;
        var timeout;

        function interceptTouchMove(){
            // and disable the touchmove features 
            window.addEventListener("touchmove", (event)=>{
                if (!'scrollable')) {
                    // no more scrolling
            }, false); 

        function scrollDetect(event){
            // wait for the result to settle
            if( timeout ) clearTimeout(timeout);

            timeout = setTimeout(function() {
                console.log( 'scrolled up detected..' );
                if (window.scrollY > 35) {
                    console.log( ' .. moved up enough to go into minimal UI mode. cover off and locking touchmove!');
                    // hide the fixed scroll-cover
                    var cover = document.querySelector('div.cover');
           = 'none';

                    // push back down to designated start-point. (as it sometimes overscrolls (this is jQuery implementation I used))
                    window.scrollY = 40;

                    // and disable the touchmove features 

                    // turn off scroll checker
                    window.removeEventListener('scroll', scrollDetect );                
            }, 200);            

        // listen to scroll to know when in minimal-ui mode.
        window.addEventListener('scroll', scrollDetect, false );

    <div class="header">
        <p>header zone</p>
    <div class="content">
    <div class="cover">
        <p>scroll to soft fullscreen</p>


Full example link here:

Adding Access-Control-Allow-Origin header response in Laravel 5.3 Passport

Working Solution

Step 1: Create Cors middleware

php artisan make:middleware Cors

Step 2: Set header in Cors middleware inside handle function

return $next($request)
        ->header('Access-Control-Allow-Origin', '*')
        ->header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');

Step 3: Add Cors class in app/Http/Kernel.php

protected $routeMiddleware = [
    'cors' => \App\Http\Middleware\Cors::class,

Step 4: Replace mapApiRoutes in app/providers/routeServiceProvider.php

         ->middleware(['api', 'cors'])

Step 5: Add your routes in routes/api.php

Route::post('example', 'controllerName@functionName')->name('example');

Node.js https pem error: routines:PEM_read_bio:no start line

You are probably using the wrong certificate file, what you need to do is generate a self signed certificate which can be done as follows

openssl req -newkey rsa:2048 -new -nodes -keyout key.pem -out csr.pem
openssl x509 -req -days 365 -in csr.pem -signkey key.pem -out server.crt

then use the server.crt

   var options = {
      key: fs.readFileSync('./key.pem', 'utf8'),
      cert: fs.readFileSync('./server.crt', 'utf8')

"This SqlTransaction has completed; it is no longer usable."... configuration error?

Had the exact same problem and just could not find the right solution. Hope this helps somebody.

I have an .NET Core 3.1 WebApi with EF Core. Upon receiving multiple calls at the same time, the applications was trying to add and save changes to the database at the same time.

In my case the problem was that the table that the data would be saved in did not have a primary key set.

Somehow EF Core missed when the migration was ran from the application that the ID in the model was supposed to be a primary key.

I found the problem by opening the SQL Profiler and seeing that all transactions was successfully submitted to the database (from the application) but only one new row was created. The profiler also showed that some type of deadlock was happening but I couldn't see much more in the trace logs of the profiler. On further inspection I noticed that the primary key identifier was missing on the column "Id".

The exceptions I got from my application was:

This SqlTransaction has completed; it is no longer usable.


An exception has been raised that is likely due to a transient failure. Consider enabling transient error resiliency by adding 'EnableRetryOnFailure()' to the 'UseSqlServer' call.

Remove Server Response Header IIS7

Following up on eddiegroves' answer, depending on the version of URLScan, you may instead prefer RemoveServerHeader=1 under [options].

I'm not sure in which version of URLScan this option was added, but it has been available in version 2.5 and later.

How to create a listbox in HTML without allowing multiple selection?

Just use the size attribute:

<select name="sometext" size="5">

To clarify, adding the size attribute did not remove the multiple selection.

The single selection works because you removed the multiple="multiple" attribute.

Adding the size="5" attribute is still a good idea, it means that at least 5 lines must be displayed. See the full reference here

Font.createFont(..) set color and size (java.awt.Font)

To set the color of a font, you must first initialize the color by doing this:

Color maroon = new Color (128, 0, 0);

Once you've done that, you then put:

Font font = new Font ("Courier New", 1, 25); //Initializes the font
c.setColor (maroon); //Sets the color of the font
c.setFont (font); //Sets the font
c.drawString ("Your text here", locationX, locationY); //Outputs the string

Note: The 1 represents the type of font and this can be used to replace Font.PLAIN and the 25 represents the size of your font.

XAMPP Object not found error

Make sure the folder you have created inside htdocs are present there and you browse the right url.

for example


make sure yoursitename folder is present

Oracle PL Sql Developer cannot find my tnsnames.ora file

I had the same problema, but as described in the manual.pdf, you have to:

You are using an Oracle Instant Client but have not set all required environment variables:

  • PATH: Needs to include the Instant Client directory where oci.dll is located
  • TNS_ADMIN: Needs to point to the directory where tnsnames.ora is located.
  • NLS_LANG: Defines the language, territory, and character set for the client.


Can I use tcpdump to get HTTP requests, response header and response body?

I would recommend using Wireshark, which has a "Follow TCP Stream" option that makes it very easy to see the full requests and responses for a particular TCP connection. If you would prefer to use the command line, you can try tcpflow, a tool dedicated to capturing and reconstructing the contents of TCP streams.

Other options would be using an HTTP debugging proxy, like Charles or Fiddler as EricLaw suggests. These have the advantage of having specific support for HTTP to make it easier to deal with various sorts of encodings, and other features like saving requests to replay them or editing requests.

You could also use a tool like Firebug (Firefox), Web Inspector (Safari, Chrome, and other WebKit-based browsers), or Opera Dragonfly, all of which provide some ability to view the request and response headers and bodies (though most of them don't allow you to see the exact byte stream, but instead how the browsers parsed the requests).

And finally, you can always construct requests by hand, using something like telnet, netcat, or socat to connect to port 80 and type the request in manually, or a tool like htty to help easily construct a request and inspect the response.

Concatenating strings in C, which method is more efficient?

Here's some madness for you, I actually went and measured it. Bloody hell, imagine that. I think I got some meaningful results.

I used a dual core P4, running Windows, using mingw gcc 4.4, building with "gcc foo.c -o foo.exe -std=c99 -Wall -O2".

I tested method 1 and method 2 from the original post. Initially kept the malloc outside the benchmark loop. Method 1 was 48 times faster than method 2. Bizarrely, removing -O2 from the build command made the resulting exe 30% faster (haven't investigated why yet).

Then I added a malloc and free inside the loop. That slowed down method 1 by a factor of 4.4. Method 2 slowed down by a factor of 1.1.

So, malloc + strlen + free DO NOT dominate the profile enough to make avoiding sprintf worth while.

Here's the code I used (apart from the loops were implemented with < instead of != but that broke the HTML rendering of this post):

void a(char *first, char *second, char *both)
    for (int i = 0; i != 1000000 * 48; i++)
        strcpy(both, first);
        strcat(both, " ");
        strcat(both, second);

void b(char *first, char *second, char *both)
    for (int i = 0; i != 1000000 * 1; i++)
        sprintf(both, "%s %s", first, second);

int main(void)
    char* first= "First";
    char* second = "Second";
    char* both = (char*) malloc((strlen(first) + strlen(second) + 2) * sizeof(char));

    // Takes 3.7 sec with optimisations, 2.7 sec WITHOUT optimisations!
    a(first, second, both);

    // Takes 3.7 sec with or without optimisations
    //b(first, second, both);

    return 0;

How to enable external request in IIS Express?

This is what I did for Windows 10 with Visual Studio 2015 to enable remote access, both with http and https:

First step is to bind your application to your internal IP address. Run cmd -> ipconfig to get the address. Open the file /{project folder}/.vs/config/applicationhost.config and scroll down until you find something like this:

<site name="Project.Web" id="2">
    <application path="/">
        <virtualDirectory path="/" physicalPath="C:\Project\Project.Web" />
        <binding protocol="http" bindingInformation="*:12345:localhost" />

Add two new bindings under bindings. You can use HTTPS as well if you like:

<binding protocol="http" bindingInformation="*:12345:" />
<binding protocol="https" bindingInformation="*:44300:" />

Add the following rule to your firewall, open a new cmd prompt as admin and run the following commands:

netsh advfirewall firewall add rule name="IISExpressWeb" dir=in protocol=tcp localport=12345 profile=private remoteip=localsubnet action=allow

netsh advfirewall firewall add rule name="IISExpressWebHttps" dir=in protocol=tcp localport=44300 profile=private remoteip=localsubnet action=allow

Now start Visual Studio as Administrator. Right click the web projects project file and select Properties. Go to the Web tab, and click Create Virtual Directory. If Visual Studio is not run as Administrator this will probably fail. Now everything should work.

enter image description here

HTML display result in text (input) field?

Do you really want the result to come up in an input box? If not, consider a table with borders set to other than transparent and use

document.getElementById('sum').innerHTML = sum;

ASP.NET Core Get Json Array using IConfiguration

For the case of returning an array of complex JSON objects from configuration, I've adapted @djangojazz's answer to use anonymous types and dynamic rather than tuples.

Given a settings section of:

"TestUsers": [
  "UserName": "TestUser",
  "Email": "[email protected]",
  "Password": "P@ssw0rd!"
  "UserName": "TestUser2",
  "Email": "[email protected]",
  "Password": "P@ssw0rd!"

You can return the object array this way:

public dynamic GetTestUsers()
    var testUsers = Configuration.GetSection("TestUsers")
                    .Select(x => new {
                        UserName = x.GetValue<string>("UserName"),
                        Email = x.GetValue<string>("Email"),
                        Password = x.GetValue<string>("Password")

    return new { Data = testUsers };

Override using CSS

As per my knowledge Inline sytle comes first so css class should not work.

Use Jquery as


   $("#demoFour li").css("display","inline");

You can also try 

#demoFour li { display:inline !important;}

Column name or number of supplied values does not match table definition

This is an older post but I want to also mention that if you have something like

insert into blah
       select * from blah2

and blah and blah2 are identical keep in mind that a computed column will throw this same error...

I just realized that when the above failed and I tried

insert into blah (cola, colb, colc)
       select cola, colb, colc from blah2

In my example it was fullname field (computed from first and last, etc)

Can I stretch text using CSS?

I'll answer for horizontal stretching of text, since the vertical is the easy part - just use "transform: scaleY()"

.stretched-text {
  letter-spacing: 2px;
  display: inline-block;
  font-size: 32px;
  transform: scaleY(0.5);
  transform-origin: 0 0;
  margin-bottom: -50%;
span {
  font-size: 16px;
  vertical-align: top;
<span class="stretched-text">this is some stretched text</span>
<span>and this is some random<br />triple line <br />not stretched text</span>

letter-spacing just adds space between letters, stretches nothing, but it's kinda relative

inline-block because inline elements are too restrictive and the code below wouldn't work otherwise

Now the combination that makes the difference

font-size to get to the size we want - that way the text will really be of the length it's supposed to be and the text before and after it will appear next to it (scaleX is just for show, the browser still sees the element at its original size when positioning other elements).

scaleY to reduce the height of the text, so that it's the same as the text beside it.

transform-origin to make the text scale from the top of the line.

margin-bottom set to a negative value, so that the next line will not be far below - preferably percentage, so that we won't change the line-height property. vertical-align set to top, to prevent the text before or after from floating to other heights (since the stretched text has a real size of 32px)

-- The simple span element has a font-size, only as a reference.

The question asked for a way to prevent the boldness of the text caused by the stretch and I still haven't given one, BUT the font-weight property has more values than just normal and bold.

I know, you just can't see that, but if you search for the appropriate fonts, you can use the more values.

What exactly does numpy.exp() do?

It calculates ex for each x in your list where e is Euler's number (approximately 2.718). In other words, np.exp(range(5)) is similar to [math.e**x for x in range(5)].

sort csv by column

To sort by MULTIPLE COLUMN (Sort by column_1, and then sort by column_2)

with open('unsorted.csv',newline='') as csvfile:
    spamreader = csv.DictReader(csvfile, delimiter=";")
    sortedlist = sorted(spamreader, key=lambda row:(row['column_1'],row['column_2']), reverse=False)

with open('sorted.csv', 'w') as f:
    fieldnames = ['column_1', 'column_2', column_3]
    writer = csv.DictWriter(f, fieldnames=fieldnames)
    for row in sortedlist:

Send file using POST from a Python script

The only thing that stops you from using urlopen directly on a file object is the fact that the builtin file object lacks a len definition. A simple way is to create a subclass, which provides urlopen with the correct file. I have also modified the Content-Type header in the file below.

import os
import urllib2
class EnhancedFile(file):
    def __init__(self, *args, **keyws):
        file.__init__(self, *args, **keyws)

    def __len__(self):
        return int(os.fstat(self.fileno())[6])

theFile = EnhancedFile('a.xml', 'r')
theUrl = ""
theHeaders= {'Content-Type': 'text/xml'}

theRequest = urllib2.Request(theUrl, theFile, theHeaders)

response = urllib2.urlopen(theRequest)


for line in response:
    print line

Formatting text in a TextBlock

You need to use Inlines:

    <Run FontWeight="Bold" FontSize="14" Text="This is WPF TextBlock Example. " />
    <Run FontStyle="Italic" Foreground="Red" Text="This is red text. " />

With binding:

    <Run FontWeight="Bold" FontSize="14" Text="{Binding BoldText}" />
    <Run FontStyle="Italic" Foreground="Red" Text="{Binding ItalicText}" />

You can also bind the other properties:

    <Run FontWeight="{Binding Weight}"
         FontSize="{Binding Size}"
         Text="{Binding LineOne}" />
    <Run FontStyle="{Binding Style}"
         Foreground="Binding Colour}"
         Text="{Binding LineTwo}" />

You can bind through converters if you have bold as a boolean (say).

How to detect installed version of MS-Office?

How about HKEY_CLASSES_ROOT\Word.Application\CurVer?

Retrieving subfolders names in S3 bucket from boto3

It took me a lot of time to figure out, but finally here is a simple way to list contents of a subfolder in S3 bucket using boto3. Hope it helps

prefix = "folderone/foldertwo/"
s3 = boto3.resource('s3')
bucket = s3.Bucket(name="bucket_name_here")
FilesNotFound = True
for obj in bucket.objects.filter(Prefix=prefix):
     print('{0}:{1}'.format(, obj.key))
     FilesNotFound = False
if FilesNotFound:
     print("ALERT", "No file in {0}/{1}".format(bucket, prefix))

jquery how to get the page's current screen top position?

var top = $('html').offset().top;

should do it.

edit: this is the negative of $(document).scrollTop()

Reduce size of legend area in barplot

The cex parameter will do that for you.

a <- c(3, 2, 2, 2, 1, 2 )
barplot(a, beside = T,
        col = 1:6, space = c(0, 2))
       legend = c("a", "b", "c", "d", "e", "f"), 
       fill = 1:6, ncol = 2,
       cex = 0.75)

The plot

How to check if a variable is not null?

There is another possible scenario I have just come across.

I did an ajax call and got data back as null, in a string format. I had to check it like this:

if(value != 'null'){}

So, null was a string which read "null" rather than really being null.

EDIT: It should be understood that I'm not selling this as the way it should be done. I had a scenario where this was the only way it could be done. I'm not sure why... perhaps the guy who wrote the back-end was presenting the data incorrectly, but regardless, this is real life. It's frustrating to see this down-voted by someone who understands that it's not quite right, and then up-voted by someone it actually helps.

Getting Gradle dependencies in IntelliJ IDEA using Gradle build

In my case,I was getting error while refreshing gradle ('View'->Tool Windows->Gradle) tab and hit "refresh" and getting this error no such property gradleversion for class jetgradleplugin.

Had to install latest intellij compatible with gradle 5+

Filtering Table rows using Jquery

I chose @nrodic's answer (thanks, by the way), but it has several drawbacks:

1) If you have rows containing "cat", "dog", "mouse", "cat dog", "cat dog mouse" (each on separate row), then when you search explicitly for "cat dog mouse", you'll be displayed "cat", "dog", "mouse", "cat dog", "cat dog mouse" rows.

2) .toLowerCase() was not implemented, that is, when you enter lower case string, rows with matching upper case text will not be showed.

So I came up with a fork of @nrodic's code, where

var data = this.value; //plain text, not an array


jo.filter(function (i, v) {
    var $t = $(this);
    var stringsFromRowNodes = $t.children("td:nth-child(n)")
    var searchText = data.toLowerCase();
    if (stringsFromRowNodes.contains(searchText)) {
        return true;
    return false;
//show the rows that match.

Here goes the full code:

How to convert a byte array to Stream

In your case:

MemoryStream ms = new MemoryStream(buffer);