Programs & Examples On #Osx server

OS X Server was a server operating system distributed by Apple Inc. which was architecturally identical to its desktop counterpart OS X, with additional functionality.

Socket File "/var/pgsql_socket/.s.PGSQL.5432" Missing In Mountain Lion (OS X Server)

I was able to solve by simply filling in for the PostgreSQL host address rather than leaving it blank. (Django Example)

    'default': {
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': 'database_name',
        'USER': 'database_user',
        'PASSWORD': 'pass',
        'HOST': '',
        'PORT': '',

Store query result in a variable using in PL/pgSQL

I think you're looking for SELECT INTO:

select into name from test_table where id = x;

That will pull the name from test_table where id is your function's argument and leave it in the name variable. Don't leave out the table name prefix on or you'll get complaints about an ambiguous reference.

What is the best or most commonly used JMX Console / Client

Alternatively, constructing a JMX console yourself doesn't need to be hard. Just plug in Jolokia and create a web page getting the attributes that you're interested in. Admittedly, it doesn't allow you to do trend analysis, but it does allow you to construct something that is really geared towards your purpose.

I constructed something in just a few lines:

Removing object properties with Lodash

You can use _.omit() for emitting the key from a JSON array if you have fewer objects:

_.forEach(data, (d) => {
    _.omit(d, ['keyToEmit1', 'keyToEmit2'])

If you have more objects, you can use the reverse of it which is _.pick():

_.forEach(data, (d) => {
    _.pick(d, ['keyToPick1', 'keyToPick2'])

How to set a parameter in a HttpServletRequest?

As mentioned in the previous posts, using an HttpServletReqiestWrapper is the way to go, however the missed part in those posts was that apart from overriding the method getParameter(), you should also override other parameter related methods to produce a consistent response. e.g. the value of a param added by the custom request wrapper should also be included in the parameters map returned by the method getParameterMap(). Here is an example:

   public class AddableHttpRequest extends HttpServletRequestWrapper {

    /** A map containing additional request params this wrapper adds to the wrapped request */
    private final Map<String, String> params = new HashMap<>();

     * Constructs a request object wrapping the given request.
     * @throws java.lang.IllegalArgumentException if the request is null
    AddableHttpRequest(final HttpServletRequest request) {

    public String getParameter(final String name) {
        // if we added one with the given name, return that one
        if ( params.get( name ) != null ) {
            return params.get( name );
        } else {
            // otherwise return what's in the original request
            return super.getParameter(name);


    public Map<String, String> getParameterMap() {
        // defaulf impl, should be overridden for an approprivate map of request params
        return super.getParameterMap();

    public Enumeration<String> getParameterNames() {
        // defaulf impl, should be overridden for an approprivate map of request params names
        return super.getParameterNames();

    public String[] getParameterValues(final String name) {
        // defaulf impl, should be overridden for an approprivate map of request params values
        return super.getParameterValues(name);

Javascript to export html table to Excel

For UTF 8 Conversion and Currency Symbol Export Use this:

var tableToExcel = (function() {
  var uri = 'data:application/;base64,'
    , template = '<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns=""><head><!--[if gte mso 9]><?xml version="1.0" encoding="UTF-8" standalone="yes"?><x:ExcelWorkbook><x:ExcelWorksheets><x:ExcelWorksheet><x:Name>{worksheet}</x:Name><x:WorksheetOptions><x:DisplayGridlines/></x:WorksheetOptions></x:ExcelWorksheet></x:ExcelWorksheets></x:ExcelWorkbook></xml><![endif]--></head><body><table>{table}</table></body></html>'
    , base64 = function(s) { return window.btoa(unescape(encodeURIComponent(s))) }
    , format = function(s, c) { return s.replace(/{(\w+)}/g, function(m, p) { return c[p]; }) }
  return function(table, name) {
      if (!table.nodeType) table = document.getElementById(table)
      var ctx = { worksheet: name || 'Worksheet', table: table.innerHTML }
    window.location.href = uri + base64(format(template, ctx))

fix Read timed out

Here are few pointers/suggestions for investigation

  1. I see that every time you vote, you call vote method which creates a fresh HTTP connection.
  2. This might be a problem. I would suggest to use a single HttpClient instance to post to the server. This way it wont create too many connections from the client side.
  3. At the end of everything, HttpClient needs to be shut and hence call httpclient.getConnectionManager().shutdown(); to release the resources used by the connections.

PHP MySQL Query Where x = $variable

What you are doing right now is you are adding . on the string and not concatenating. It should be,

$result = mysqli_query($con,"SELECT `note` FROM `glogin_users` WHERE email = '".$email."'");

or simply

$result = mysqli_query($con,"SELECT `note` FROM `glogin_users` WHERE email = '$email'");

How do I disable a Pylint warning?

Python syntax does permit more than one statement on a line, separated by semicolon (;). However, limiting each line to one statement makes it easier for a human to follow a program's logic when reading through it.

So, another way of solving this issue, is to understand why the lint message is there and not put more than one statement on a line.

Yes, you may find it easier to write multiple statements per line, however, Pylint is for every other reader of your code not just you.

How to create a Java / Maven project that works in Visual Studio Code?

An alternative way is to install the Maven for Java plugin and create a maven project within Visual Studio. The steps are described in the official documentation:

  1. From the Command Palette (Crtl+Shift+P), select Maven: Generate from Maven Archetype and follow the instructions, or
  2. Right-click on a folder and select Generate from Maven Archetype.

Remove multiple items from a Python list in just one statement

You can do it in one line by converting your lists to sets and using set.difference:

item_list = ['item', 5, 'foo', 3.14, True]
list_to_remove = ['item', 5, 'foo']

final_list = list(set(item_list) - set(list_to_remove))

Would give you the following output:

final_list = [3.14, True]

Note: this will remove duplicates in your input list and the elements in the output can be in any order (because sets don't preserve order). It also requires all elements in both of your lists to be hashable.

Print JSON parsed object?

The following code will display complete json data in alert box

var data= '{"employees":[' +
'{"firstName":"John","lastName":"Doe" },' +
'{"firstName":"Anna","lastName":"Smith" },' +
'{"firstName":"Peter","lastName":"Jones" }]}';

json = JSON.parse(data);

Hbase quickly count number of rows

To count the Hbase table record count on a proper YARN cluster you have to set the map reduce job queue name as well:

hbase org.apache.hadoop.hbase.mapreduce.RowCounter -Dmapreduce.job.queuename= < Your Q Name which you have SUBMIT access>

High Quality Image Scaling Library

I have some improve for Doctor Jones's answer.

It works for who wanted to how to proportional resize the image. It tested and worked for me.

The methods of class I added:

public static System.Drawing.Bitmap ResizeImage(System.Drawing.Image image, Size size)
    return ResizeImage(image, size.Width, size.Height);

public static Size GetProportionedSize(Image image, int maxWidth, int maxHeight, bool withProportion)
    if (withProportion)
        double sourceWidth = image.Width;
        double sourceHeight = image.Height;

        if (sourceWidth < maxWidth && sourceHeight < maxHeight)
            maxWidth = (int)sourceWidth;
            maxHeight = (int)sourceHeight;
            double aspect = sourceHeight / sourceWidth;

            if (sourceWidth < sourceHeight)
                maxWidth = Convert.ToInt32(Math.Round((maxHeight / aspect), 0));
                maxHeight = Convert.ToInt32(Math.Round((maxWidth * aspect), 0));

    return new Size(maxWidth, maxHeight);

and new available using according to this codes:

using (var resized = ImageUtilities.ResizeImage(image, ImageUtilities.GetProportionedSize(image, 50, 100)))
    ImageUtilities.SaveJpeg(@"C:\myimage.jpeg", resized, 90);

Sort JavaScript object by key

The other answers to this question are outdated, never matched implementation reality, and have officially become incorrect now that the ES6 / ES2015 spec has been published.

See the section on property iteration order in Exploring ES6 by Axel Rauschmayer:

All methods that iterate over property keys do so in the same order:

  1. First all Array indices, sorted numerically.
  2. Then all string keys (that are not indices), in the order in which they were created.
  3. Then all symbols, in the order in which they were created.

So yes, JavaScript objects are in fact ordered, and the order of their keys/properties can be changed.

Here’s how you can sort an object by its keys/properties, alphabetically:

const unordered = {
  'b': 'foo',
  'c': 'bar',
  'a': 'baz'

// ? '{"b":"foo","c":"bar","a":"baz"}'

const ordered = Object.keys(unordered).sort().reduce(
  (obj, key) => { 
    obj[key] = unordered[key]; 
    return obj;

// ? '{"a":"baz","b":"foo","c":"bar"}'

Use var instead of const for compatibility with ES5 engines.

Subquery returned more than 1 value.This is not permitted when the subquery follows =,!=,<,<=,>,>= or when the subquery is used as an expression

The problem is that these two queries are each returning more than one row:

select isbn from dbo.lending where (act between @fdate and @tdate) and (stat ='close')
select isbn from dbo.lending where lended_date between @fdate and @tdate

You have two choices, depending on your desired outcome. You can either replace the above queries with something that's guaranteed to return a single row (for example, by using SELECT TOP 1), OR you can switch your = to IN and return multiple rows, like this:

select * from dbo.books where isbn IN (select isbn from dbo.lending where (act between @fdate and @tdate) and (stat ='close'))

Rename specific column(s) in pandas

A much faster implementation would be to use list-comprehension if you need to rename a single column.

df.columns = ['log(gdp)' if x=='gdp' else x for x in df.columns]

If the need arises to rename multiple columns, either use conditional expressions like:

df.columns = ['log(gdp)' if x=='gdp' else 'cap_mod' if x=='cap' else x for x in df.columns]

Or, construct a mapping using a dictionary and perform the list-comprehension with it's get operation by setting default value as the old name:

col_dict = {'gdp': 'log(gdp)', 'cap': 'cap_mod'}   ## key?old name, value?new name

df.columns = [col_dict.get(x, x) for x in df.columns]


df.rename(columns={'gdp':'log(gdp)'}, inplace=True)
10000 loops, best of 3: 168 µs per loop

df.columns = ['log(gdp)' if x=='gdp' else x for x in df.columns]
10000 loops, best of 3: 58.5 µs per loop

Android: How to programmatically access the device serial number shown in the AVD manager (API Version 8)

From Android P, defining the READ_PHONE_STATE permission in AndroidManifest only, will not work. We have to actually request for the permission. Below code works for me:

@RequiresApi(api = Build.VERSION_CODES.P)
protected void onCreate(Bundle savedInstanceState) {

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_PHONE_STATE}, 101);

@RequiresApi(api = Build.VERSION_CODES.O)
protected void onResume() {
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
@RequiresApi(api = Build.VERSION_CODES.O)
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
    switch (requestCode) {
        case 101:
            if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            if (ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE) != PackageManager.PERMISSION_GRANTED) {
        } else {
            //not granted
            super.onRequestPermissionsResult(requestCode, permissions, grantResults);

Add this permissions in AndroidManifest.xml

<uses-permission android:name = "android.permission.INTERNET"/>
<uses-permission android:name = "android.permission.READ_PHONE_STATE" />

Hope this helps.

Thank You, MJ

Node.js - SyntaxError: Unexpected token import

if you can use 'babel', try to add build scripts in package.json(--presets=es2015) as below. it make to precompile import code to es2015

"build": "babel server --out-dir build --presets=es2015 && webpack"

Under what conditions is a JSESSIONID created?

Beware if your page is including other .jsp or .jspf (fragment)! If you don't set

<%@ page session="false" %>

on them as well, the parent page will end up starting a new session and setting the JSESSIONID cookie.

For .jspf pages in particular, this happens if you configured your web.xml with such a snippet:


in order to enable scriptlets inside them.

If file exists then delete the file

IF both POS_History_bim_data_*.zip and POS_History_bim_data_*.zip.trg exists in  Y:\ExternalData\RSIDest\ Folder then Delete File Y:\ExternalData\RSIDest\Target_slpos_unzip_done.dat

XMLHttpRequest cannot load file. Cross origin requests are only supported for HTTP

I was facing this error while I deployed my Web API project locally and I was calling API project only with this URL given below:


Since the error message says it is not http:// then I changed the URL and put a prefix http as given below and the error was gone.


using javascript to detect whether the url exists before display in iframe

I found this worked in my scenario.

The jqXHR.success(), jqXHR.error(), and jqXHR.complete() callback methods introduced in jQuery 1.5 are deprecated as of jQuery 1.8. To prepare your code for their eventual removal, use jqXHR.done(),, and jqXHR.always() instead.

$.get("").done(function () {
}).fail(function () {

Java String declaration

String str = new String("SOME")

always create a new object on the heap

String str="SOME" 

uses the String pool

Try this small example:

        String s1 = new String("hello");
        String s2 = "hello";
        String s3 = "hello";

        System.err.println(s1 == s2);
        System.err.println(s2 == s3);

To avoid creating unnecesary objects on the heap use the second form.

checking memory_limit in PHP

Not so exact but simpler solution:

$limit = str_replace(array('G', 'M', 'K'), array('000000000', '000000', '000'), ini_get('memory_limit'));
if($limit < 500000000) ini_set('memory_limit', '500M');                     

php, mysql - Too many connections to database error

If you are reaching the mac connection limit go to /etc/my.cnf and under the [mysqld] section add max_connections = 500

and restart MySQL.

Add a new column to existing table in a migration

I'll add on to mike3875's answer for future readers using Laravel 5.1 and onward.

To make things quicker, you can use the flag "--table" like this:

php artisan make:migration add_paid_to_users --table="users"

This will add the up and down method content automatically:

 * Run the migrations.
 * @return void
public function up()
    Schema::table('users', function (Blueprint $table) {

Similarily, you can use the --create["table_name"] option when creating new migrations which will add more boilerplate to your migrations. Small point, but helpful when doing loads of them!

How do I correctly detect orientation change using Phonegap on iOS?

if (window.DeviceOrientationEvent) {
    // Listen for orientation changes
    window.addEventListener("orientationchange", orientationChangeHandler);
    function orientationChangeHandler(evt) {
        // Announce the new orientation number
        // alert(screen.orientation);
        // Find matches
        var mql = window.matchMedia("(orientation: portrait)");

        if (mql.matches)  //true

How to animate the change of image in an UIImageView?

Swift 4 This is just awesome

  self.imgViewPreview.transform = CGAffineTransform(scaleX: 0, y: 0)
          UIView.animate(withDuration: 1, delay: 0, usingSpringWithDamping: 0.3, initialSpringVelocity: 0, options: .curveEaseOut, animations: {
              self.imgViewPreview.image = newImage
              self.imgViewPreview.transform = .identity
          }, completion: nil)

Javascript callback when IFRAME is finished loading?

I have had to do this in cases where documents such as word docs and pdfs were being streamed to the iframe and found a solution that works pretty well. The key is handling the onreadystatechanged event on the iframe.

Lets say the name of your frame is "myIframe". First somewhere in your code startup (I do it inline any where after the iframe) add something like this to register the event handler:

document.getElementById('myIframe').onreadystatechange = MyIframeReadyStateChanged;

I was not able to use an onreadystatechage attribute on the iframe, I can't remember why, but the app had to work in IE 7 and Safari 3, so that may of been a factor.

Here is an example of a how to get the complete state:

function MyIframeReadyStateChanged()
    if(document.getElementById('myIframe').readyState == 'complete')
        // Do your complete stuff here.

Ideal way to cancel an executing AsyncTask

With reference to Yanchenko's answer on 29 April '10: Using a 'while(running)' approach is neat when your code under 'doInBackground' has to be executed multiple times during every execution of the AsyncTask. If your code under 'doInBackground' has to be executed only once per execution of the AsyncTask, wrapping all your code under 'doInBackground' in a 'while(running)' loop will not stop the background code (background thread) from running when the AsyncTask itself is cancelled, because the 'while(running)' condition will only be evaluated once all the code inside the while loop has been executed at least once. You should thus either (a.) break up your code under 'doInBackground' into multiple 'while(running)' blocks or (b.) perform numerous 'isCancelled' checks throughout your 'doInBackground' code, as explained under "Cancelling a task" at

For option (a.) one can thus modify Yanchenko's answer as follows:

public class MyTask extends AsyncTask<Void, Void, Void> {

private volatile boolean running = true;


protected void onCancelled() {
    running = false;

protected Void doInBackground(Void... params) {

    // does the hard work

    while (running) {
        // part 1 of the hard work

    while (running) {
        // part 2 of the hard work

    // ...

    while (running) {
        // part x of the hard work
    return null;

// ...

For option (b.) your code in 'doInBackground' will look something like this:

public class MyTask extends AsyncTask<Void, Void, Void> {


protected Void doInBackground(Void... params) {

    // part 1 of the hard work
    // ...
    if (isCancelled()) {return null;}

    // part 2 of the hard work
    // ...
    if (isCancelled()) {return null;}

    // ...

    // part x of the hard work
    // ...
    if (isCancelled()) {return null;}

// ...

Correct way to find max in an Array in Swift

In Swift 2.0, the minElement and maxElement become methods of SequenceType protocol, you should call them like:

let a = [1, 2, 3]
print(a.maxElement()) //3
print(a.minElement()) //1

Using maxElement as a function like maxElement(a) is unavailable now.

The syntax of Swift is in flux, so I can just confirm this in Xcode version7 beta6.

It may be modified in the future, so I suggest that you'd better check the doc before you use these methods.

Call Activity method from adapter

You can do it this way:

Declare interface:

public interface MyInterface{
    public void foo();

Let your Activity imlement it:

    public class MyActivity extends Activity implements MyInterface{
        public void foo(){
            //do stuff
        public onCreate(){
            //your code
            MyAdapter adapter = new MyAdapter(this); //this will work as your 
                                                     //MyInterface listener

Then pass your activity to ListAdater:

public MyAdapter extends BaseAdater{
    private MyInterface listener;

    public MyAdapter(MyInterface listener){
        this.listener = listener;

And somewhere in adapter, when you need to call that Activity method:;

How do I assert my exception message with JUnit Test annotation?

@Test (expectedExceptions = ValidationException.class, expectedExceptionsMessageRegExp = "This is not allowed")
public void testInvalidValidation() throws Exception{
     //test code

Excel Formula to SUMIF date falls in particular month

Try this instead:


It's an array formula, so you will need to enter it with the Control-Shift-Enter key combination.

Here's how the formula works.

  1. MONTH($A$2:$A$6) creates an array of numeric values of the month for the dates in A2:A6, that is,
    {1, 1, 1, 2, 2}.
  2. Then the comparison {1, 1, 1, 2, 2}= 1 produces the array {TRUE, TRUE, TRUE, FALSE, FALSE}, which comprises the condition for the IF statement.
  3. The IF statement then returns an array of values, with {430, 96, 400.. for the values of the sum ranges where the month value equals 1 and ..0,0} where the month value does not equal 1.
  4. That array {430, 96, 400, 0, 0} is then summed to get the answer you are looking for.

This is essentially equivalent to what the SUMIF and SUMIFs functions do. However, neither of those functions support the kind of calculation you tried to include in the conditional.

It's also possible to drop the IF completely. Since TRUE and FALSE can also be treated as 1 and 0, this formula--=SUM((MONTH($A$2:$A$6)=1)*$B$2:$B$6)--also works.

Heads up: This does not work in Google Spreadsheets

How to run a single test with Mocha?

You can try "it.only"

 it.only('Test one ', () => {

it('Test two ', () => {


in this the first one only will execute

NoClassDefFoundError for code in an Java library on Android

I met NoClassDefFoundError for a class that exists in my project (not a library class). The class exists but i got NoClassDefFoundError. In my case, the problem was multidex support. The problem and solution is here: Android Multidex and support libraries

You get this error for Android versions lower than 5.0.

Jquery resizing image

So much code here, but I think this is the best answer

function resize() {
            var input = $("#picture");
            var maxWidth = 300;
            var maxHeight = 300;
            var width = input.width();
            var height = input.height();
            var ratioX = (maxWidth / width);
            var ratioY = (maxHeight / height);
            var ratio = Math.min(ratioX, ratioY);

            var newWidth  = (width * ratio);
            var newHeight = (height * ratio);
            input.css("width", newWidth);
            input.css("height", newHeight);

How to clear cache in Yarn?

Also note that the cached directory is located in ~/.yarn-cache/:

yarn cache clean: cleans that directory

yarn cache list: shows the list of cached dependencies

yarn cache dir: prints out the path of your cached directory

Catch checked change event of a checkbox

In my experience, I've had to leverage the event's currentTarget:

$("#dingus").click( function (event) {
   if ($(event.currentTarget).is(':checked')) {
     //checkbox is checked

How can I check whether an array is null / empty?

You can also check whether there is any elements in the array by finding out its length, then put it into if-else statement to check whether it is null.

int[] k = new int[3];
if(k.length == 0)
//do something

Retrieve the commit log for a specific line in a file?

Here is a solution that defines a git alias, so you will be able use it like that :

git rblame -M -n -L '/REGEX/,+1' FILE

Output example :

00000000 18 (Not Committed Yet 2013-08-19 13:04:52 +0000 728) fooREGEXbar
15227b97 18 (User1 2013-07-11 18:51:26 +0000 728) fooREGEX
1748695d 23 (User2 2013-03-19 21:09:09 +0000 741) REGEXbar

You can define the alias in your .gitconfig or simply run the following command

git config alias.rblame !sh -c 'while line=$(git blame "$@" $commit 2>/dev/null); do commit=${line:0:8}^; [ 00000000^ == $commit ] && commit=$(git rev-parse HEAD); echo $line; done' dumb_param

This is an ugly one-liner, so here is a de-obfuscated equivalent bash function :

git-rblame () {
    local commit line
    while line=$(git blame "$@" $commit 2>/dev/null); do
        if [ "00000000^" == "$commit" ]; then
            commit=$(git rev-parse HEAD)
        echo $line

The pickaxe solution ( git log --pickaxe-regex -S'REGEX' ) will only give you line additions/deletions, not the other alterations of the line containing the regular expression.

A limitation of this solution is that git blame only returns the 1st REGEX match, so if multiple matches exist the recursion may "jump" to follow another line. Be sure to check the full history output to spot those "jumps" and then fix your REGEX to ignore the parasite lines.

Finally, here is an alternate version that run git show on each commit to get the full diff :

git config alias.rblameshow !sh -c 'while line=$(git blame "$@" $commit 2>/dev/null); do commit=${line:0:8}^; [ 00000000^ == $commit ] && commit=$(git rev-parse HEAD); git show $commit; done' dumb_param

The equivalent of a GOTO in python

I entirely agree that goto is poor poor coding, but no one has actually answered the question. There is in fact a goto module for Python (though it was released as an April fool joke and is not recommended to be used, it does work).

Convert pandas Series to DataFrame

Rather than create 2 temporary dfs you can just pass these as params within a dict using the DataFrame constructor:

pd.DataFrame({'email':sf.index, 'list':sf.values})

There are lots of ways to construct a df, see the docs

Can I install Python 3.x and 2.x on the same Windows computer?

I'm using 2.5, 2.6, and 3.0 from the shell with one line batch scripts of the form:

:: The @ symbol at the start turns off the prompt from displaying the command.
:: The % represents an argument, while the * means all of them.
@c:\programs\pythonX.Y\python.exe %*

Name them pythonX.Y.bat and put them somewhere in your PATH. Copy the file for the preferred minor version (i.e. the latest) to pythonX.bat. (E.g. copy python2.6.bat python2.bat.) Then you can use python2 from anywhere.

However, this doesn't help or even affect the Windows file association situation. For that you'll need a launcher program that reads the #! line, and then associate that with .py and .pyw files.

RESTful URL design for search

My advice would be this:

  Returns list of garages (think JSON array here)
  Returns specific garage
  Returns list of cars in garage
  Returns list of all cars in all garages (may not be practical of course)
  Returns list of all cars
  Returns specific car
  Returns lists of all posible colors for cars
  Returns list of cars of the specific colors (yes commas are allowed :) )


  Returns list of all red,blue, and green cars with 2 doors.
  Same idea as the above but a lil more intuitive.
  All cars that are red, blue, green and have either two or four doors.

Hopefully that gives you the idea. Essentially your Rest API should be easily discoverable and should enable you to browse through your data. Another advantage with using URLs and not query strings is that you are able to take advantage of the native caching mechanisms that exist on the web server for HTTP traffic.

Here's a link to a page describing the evils of query strings in REST:

I used Google's cache because the normal page wasn't working for me here's that link as well:

'Conda' is not recognized as internal or external command

When you install anaconda on windows now, it doesn't automatically add Python or Conda to your path.

While during the installation process you can check this box, you can also add python and/or python to your path manually (as you can see below the image)

enter image description here

If you don’t know where your conda and/or python is, you type the following commands into your anaconda prompt

where python
where conda

Next, you can add Python and Conda to your path by using the setx command in your command prompt (replace C:\Users\mgalarnyk\Anaconda2 with the results you got when running where python and where conda).

SETX PATH "%PATH%;C:\Users\mgalarnyk\Anaconda2\Scripts;C:\Users\mgalarnyk\Anaconda2"

Next close that command prompt and open a new one. Congrats you can now use conda and python


Filtering a list based on a list of booleans

You're looking for itertools.compress:

>>> from itertools import compress
>>> list_a = [1, 2, 4, 6]
>>> fil = [True, False, True, False]
>>> list(compress(list_a, fil))
[1, 4]

Timing comparisons(py3.x):

>>> list_a = [1, 2, 4, 6]
>>> fil = [True, False, True, False]
>>> %timeit list(compress(list_a, fil))
100000 loops, best of 3: 2.58 us per loop
>>> %timeit [i for (i, v) in zip(list_a, fil) if v]  #winner
100000 loops, best of 3: 1.98 us per loop

>>> list_a = [1, 2, 4, 6]*100
>>> fil = [True, False, True, False]*100
>>> %timeit list(compress(list_a, fil))              #winner
10000 loops, best of 3: 24.3 us per loop
>>> %timeit [i for (i, v) in zip(list_a, fil) if v]
10000 loops, best of 3: 82 us per loop

>>> list_a = [1, 2, 4, 6]*10000
>>> fil = [True, False, True, False]*10000
>>> %timeit list(compress(list_a, fil))              #winner
1000 loops, best of 3: 1.66 ms per loop
>>> %timeit [i for (i, v) in zip(list_a, fil) if v] 
100 loops, best of 3: 7.65 ms per loop

Don't use filter as a variable name, it is a built-in function.

JAX-RS / Jersey how to customize error handling?

Jersey throws an com.sun.jersey.api.ParamException when it fails to unmarshall the parameters so one solution is to create an ExceptionMapper that handles these types of exceptions:

public class ParamExceptionMapper implements ExceptionMapper<ParamException> {
    public Response toResponse(ParamException exception) {
        return Response.status(Status.BAD_REQUEST).entity(exception.getParameterName() + " incorrect type").build();

How to lookup JNDI resources on WebLogic?

You should be able to simply do this:

Context context = new InitialContext();
dataSource = (javax.sql.DataSource) context.lookup("jdbc/myDataSource");

If you are looking it up from a remote destination you need to use the WL initial context factory like this:

Hashtable<String, String> h = new Hashtable<String, String>(7);
h.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory");
h.put(Context.PROVIDER_URL, pURL); //For example "t3://"
h.put(Context.SECURITY_PRINCIPAL, pUsername);
h.put(Context.SECURITY_CREDENTIALS, pPassword);

InitialContext context = new InitialContext(h);
dataSource = (javax.sql.DataSource) context.lookup("jdbc/myDataSource");


Convert np.array of type float64 to type uint8 scaling values

Considering that you are using OpenCV, the best way to convert between data types is to use normalize function.

img_n = cv2.normalize(src=img, dst=None, alpha=0, beta=255, norm_type=cv2.NORM_MINMAX, dtype=cv2.CV_8U)

However, if you don't want to use OpenCV, you can do this in numpy

def convert(img, target_type_min, target_type_max, target_type):
    imin = img.min()
    imax = img.max()

    a = (target_type_max - target_type_min) / (imax - imin)
    b = target_type_max - a * imax
    new_img = (a * img + b).astype(target_type)
    return new_img

And then use it like this

imgu8 = convert(img16u, 0, 255, np.uint8)

This is based on the answer that I found on crossvalidated board in comments under this solution

ModuleNotFoundError: What does it mean __main__ is not a package?

Remove the dot and import absolute_import in the beginning of your file

from __future__ import absolute_import

from p_02_paying_debt_off_in_a_year import compute_balance_after

How do you create a Spring MVC project in Eclipse?

This is the easiest way :

step 1) install Spring Tool Suite (STS) for eclipse (version 3.7.0RELEASE or above) To do this you can go to Help >> eclipse market place , then type Spring Tool suite in search box.

step 2) now go to file >> new >> spring project as shown in the image below enter image description here

step 3)now choose the template as "spring MVC Project" and give a name to your project on the top as shown below ( I named it 'SpringProject') enter image description here

step 4)now give a base package name like this enter image description here

and that is . The project will be created in a few minutes and Now you can right click on it and run on server.

How to set python variables to true or false?

you have to use capital True and False not true and false

Index (zero based) must be greater than or equal to zero

using System;

namespace ConsoleApp1
    class Program
        static void Main()
            Console.WriteLine("Enter Your FirstName ");
            String FirstName = Console.ReadLine();

            Console.WriteLine("Enter Your LastName ");
            String LastName = Console.ReadLine();

            Console.WriteLine("Hello {0}, {1} ", FirstName, LastName);



System.Net.WebException: The operation has timed out

I'm not sure about your first code sample where you use WebClient.UploadValues, it's not really enough to go on, could you paste more of your surrounding code? Regarding your WebRequest code, there are two things at play here:

  1. You're only requesting the headers of the response**, you never read the body of the response by opening and reading (to its end) the ResponseStream. Because of this, the WebRequest client helpfully leaves the connection open, expecting you to request the body at any moment. Until you either read the response body to completion (which will automatically close the stream for you), clean up and close the stream (or the WebRequest instance) or wait for the GC to do its thing, your connection will remain open.

  2. You have a default maximum amount of active connections to the same host of 2. This means you use up your first two connections and then never dispose of them so your client isn't given the chance to complete the next request before it reaches its timeout (which is milliseconds, btw, so you've set it to 0.2 seconds - the default should be fine).

If you don't want the body of the response (or you've just uploaded or POSTed something and aren't expecting a response), simply close the stream, or the client, which will close the stream for you.

The easiest way to fix this is to make sure you use using blocks on disposable objects:

for (int i = 0; i < ops1; i++)
    Uri myUri = new Uri(site);
    WebRequest myWebRequest = WebRequest.Create(myUri);
    //myWebRequest.Timeout = 200;
    using (WebResponse myWebResponse = myWebRequest.GetResponse())
        // Do what you want with myWebResponse.Headers.
    } // Your response will be disposed of here

Another solution is to allow 200 concurrent connections to the same host. However, unless you're planning to multi-thread this operation so you'd need multiple, concurrent connections, this won't really help you:

 ServicePointManager.DefaultConnectionLimit = 200;

When you're getting timeouts within code, the best thing to do is try to recreate that timeout outside of your code. If you can't, the problem probably lies with your code. I usually use cURL for that, or just a web browser if it's a simple GET request.

** In reality, you're actually requesting the first chunk of data from the response, which contains the HTTP headers, and also the start of the body. This is why it's possible to read HTTP header info (such as Content-Encoding, Set-Cookie etc) before reading from the output stream. As you read the stream, further data is retrieved from the server. WebRequest's connection to the server is kept open until you reach the end of this stream (effectively closing it as it's not seekable), manually close it yourself or it is disposed of. There's more about this here.

How to create nested directories using Mkdir in Golang?

If the issue is to create all the necessary parent directories, you could consider using os.MkDirAll()

MkdirAll creates a directory named path, along with any necessary parents, and returns nil, or else returns an error.

The path_test.go is a good illustration on how to use it:

func TestMkdirAll(t *testing.T) {
    tmpDir := TempDir()
    path := tmpDir + "/_TestMkdirAll_/dir/./dir2"
    err := MkdirAll(path, 0777)
    if err != nil {
    t.Fatalf("MkdirAll %q: %s", path, err)
    defer RemoveAll(tmpDir + "/_TestMkdirAll_")

(Make sure to specify a sensible permission value, as mentioned in this answer)

Adding a newline into a string in C#

Based on your replies to everyone else, something like this is what you're looking for.

string file = @"C:\file.txt";
string strToProcess = "fkdfdsfdflkdkfk@dfsdfjk72388389@kdkfkdfkkl@jkdjkfjd@jjjk@";
string[] lines = strToProcess.Split(new char[] { '@' }, StringSplitOptions.RemoveEmptyEntries);

using (StreamWriter writer = new StreamWriter(file))
    foreach (string line in lines)
        writer.WriteLine(line + "@");

How to add local .jar file dependency to build.gradle file?

A simple way to do this is

compile fileTree(include: ['*.jar'], dir: 'libs')

it will compile all the .jar files in your libs directory in App.

Find all tables containing column with specified name - MS SQL Server

I used this for the same purpose and it worked:

  where TABLE_CATALOG= 'theDatabase'
  and COLUMN_NAME like 'theCol%'

Cleanest way to build an SQL string in Java

I have been working on a Java servlet application that needs to construct very dynamic SQL statements for adhoc reporting purposes. The basic function of the app is to feed a bunch of named HTTP request parameters into a pre-coded query, and generate a nicely formatted table of output. I used Spring MVC and the dependency injection framework to store all of my SQL queries in XML files and load them into the reporting application, along with the table formatting information. Eventually, the reporting requirements became more complicated than the capabilities of the existing parameter mapping frameworks and I had to write my own. It was an interesting exercise in development and produced a framework for parameter mapping much more robust than anything else I could find.

The new parameter mappings looked as such:

select as "App", 
       ${optional(" app.owner as "Owner", "):showOwner} as "Server", sum(act.trans_ct) as "Trans"
  from activity_records act, servers sv, applications app
 where act.server_id =
   and act.app_id =
   and = ${integer(0,50):serverId}
   and in ${integerList(50):appId}
 group by, ${optional(" app.owner, "):showOwner}
 order by,

The beauty of the resulting framework was that it could process HTTP request parameters directly into the query with proper type checking and limit checking. No extra mappings required for input validation. In the example query above, the parameter named serverId would be checked to make sure it could cast to an integer and was in the range of 0-50. The parameter appId would be processed as an array of integers, with a length limit of 50. If the field showOwner is present and set to "true", the bits of SQL in the quotes will be added to the generated query for the optional field mappings. field Several more parameter type mappings are available including optional segments of SQL with further parameter mappings. It allows for as complex of a query mapping as the developer can come up with. It even has controls in the report configuration to determine whether a given query will have the final mappings via a PreparedStatement or simply ran as a pre-built query.

For the sample Http request values:

showOwner: true
serverId: 20
appId: 1,2,3,5,7,11,13

It would produce the following SQL:

select as "App", 
       app.owner as "Owner", as "Server", sum(act.trans_ct) as "Trans"
  from activity_records act, servers sv, applications app
 where act.server_id =
   and act.app_id =
   and = 20
   and in (1,2,3,5,7,11,13)
 group by,  app.owner,
 order by,

I really think that Spring or Hibernate or one of those frameworks should offer a more robust mapping mechanism that verifies types, allows for complex data types like arrays and other such features. I wrote my engine for only my purposes, it isn't quite read for general release. It only works with Oracle queries at the moment and all of the code belongs to a big corporation. Someday I may take my ideas and build a new open source framework, but I'm hoping one of the existing big players will take up the challenge.

How do I get a reference to the app delegate in Swift?

Here's an extension for UIApplicationDelegate that avoids hardcoding the AppDelegate class name:

extension UIApplicationDelegate {

    static var shared: Self {    
        return UIApplication.shared.delegate! as! Self

// use like this:
let appDelegate = MyAppDelegate.shared // will be of type MyAppDelegate

ng-mouseover and leave to toggle item using mouse in angularjs

I would simply make the assignment happen in the ng-mouseover and ng-mouseleave; no need to bother js file :)

<ul ng-repeat="task in tasks">
    <li ng-mouseover="hoverEdit = true" ng-mouseleave="hoverEdit = false">{{}}</li>
    <span ng-show="hoverEdit"><a>Edit</a></span>

How to compare DateTime in C#?

Microsoft has also implemented the operators '<' and '>'. So you use these to compare two dates.

if (date1 < DateTime.Now)
   Console.WriteLine("Less than the current time!");

Notification Icon with the new Firebase Cloud Messaging system

Unfortunately this was a limitation of Firebase Notifications in SDK 9.0.0-9.6.1. When the app is in the background the launcher icon is use from the manifest (with the requisite Android tinting) for messages sent from the console.

With SDK 9.8.0 however, you can override the default! In your AndroidManifest.xml you can set the following fields to customise the icon and color:

        android:resource="@drawable/notification_icon" />
<meta-data android:name=""
        android:resource="@color/google_blue" />

Note that if the app is in the foreground (or a data message is sent) you can completely use your own logic to customise the display. You can also always customise the icon if sending the message from the HTTP/XMPP APIs.

Image resizing client-side with JavaScript before upload to the server

Here's a gist which does this:

(an es6 version, and a .js version which can be included in a script tag)

You can use it as follows:

<input type="file" id="select">
<img id="preview">
document.getElementById('select').onchange = function(evt) {
    ImageTools.resize(this.files[0], {
        width: 320, // maximum width
        height: 240 // maximum height
    }, function(blob, didItResize) {
        // didItResize will be true if it managed to resize it, otherwise false (and will return the original file as 'blob')
        document.getElementById('preview').src = window.URL.createObjectURL(blob);
        // you can also now upload this blob using an XHR.

It includes a bunch of support detection and polyfills to make sure it works on as many browsers as I could manage.

(it also ignores gif images - in case they're animated)

Java Generics With a Class & an Interface - Together

Actually, you can do what you want. If you want to provide multiple interfaces or a class plus interfaces, you have to have your wildcard look something like this:

<T extends ClassA & InterfaceB>

See the Generics Tutorial at, specifically the Bounded Type Parameters section, at the bottom of the page. You can actually list more than one interface if you wish, using & InterfaceName for each one that you need.

This can get arbitrarily complicated. To demonstrate, see the JavaDoc declaration of Collections#max, which (wrapped onto two lines) is:

public static <T extends Object & Comparable<? super T>> T
                                           max(Collection<? extends T> coll)

why so complicated? As said in the Java Generics FAQ: To preserve binary compatibility.

It looks like this doesn't work for variable declaration, but it does work when putting a generic boundary on a class. Thus, to do what you want, you may have to jump through a few hoops. But you can do it. You can do something like this, putting a generic boundary on your class and then:

class classB { }
interface interfaceC { }

public class MyClass<T extends classB & interfaceC> {
    Class<T> variable;

to get variable that has the restriction that you want. For more information and examples, check out page 3 of Generics in Java 5.0. Note, in <T extends B & C>, the class name must come first, and interfaces follow. And of course you can only list a single class.

Does Notepad++ show all hidden characters?

Double check your text with the Hex Editor Plug-in. In your case there may have been some control characters which have crept into your text. Usually you'll look at the white-space, and it will say 32 32 32 32, or for Unicode 32 00 32 00 32 00 32 00. You may find the problem this way, providing there isn't masses of code.

Download the Hex Plugin from here;

Download image from the site in .NET/C#

The best practice to download an image from Server or from Website and store it locally.

WebClient client=new Webclient();
client.DownloadFile("WebSite URL","C:\\....image.jpg");

How do I use Maven through a proxy?

I also had this problem, and I solved it by editing the settings.xml file in my .m2 folder. My settings.xml is like this now:


Java resource as file

Try this:

ClassLoader.getResourceAsStream ("some/pkg/");

There are more methods available, e.g. see here:

How to center an iframe horizontally?

Add display:block; to your iframe css.

div, iframe {
    width: 100px;
    height: 50px;
    margin: 0 auto;
    background-color: #777;

iframe {
    display: block;
<iframe src="data:,iframe"></iframe>

How to convert latitude or longitude to meters?

One nautical mile (1852 meters) is defined as one arcminute of longitude at the equator. However, you need to define a map projection (see also UTM) in which you are working for the conversion to really make sense.

How do I pass an object from one activity to another on Android?

Your object can also implement the Parcelable interface. Then you can use the Bundle.putParcelable() method and pass your object between activities within intent.

The Photostream application uses this approach and may be used as a reference.

How can I create a keystore?

If you don't want to or can't use Android Studio, you can use the create-android-keystore NPM tool:

$ create-android-keystore quick

Which results in a newly generated keystore in the current directory.

More info:

read file from assets

If you use other any class other than Activity, you might want to do like,

BufferedReader bufferedReader = new BufferedReader(new InputStreamReader( YourApplication.getInstance().getAssets().open("text.txt"), "UTF-8"));

Compilation error: stray ‘\302’ in program etc

With me this error ocurred when I copied and pasted a code in text format to my editor (gedit). The code was in a text document (.odt) and I copied it and pasted it into gedit. If you did the same, you have manually rewrite the code.

Find character position and update file name

The string is a .NET string so you can use .NET methods. In your case:

$index = "The string".IndexOf(" ")

will return 3, which is the first occurrence of space in the string. For more information see:

For your need try something like:

$s.SubString($s.IndexOf("_") + 1, $s.LastIndexOf(".") - $s.IndexOf("_") - 1)

Or you could use regexps:

if ($s -Match '(_)(.*)(\.)[^.]*$') {  $matches[2] }

(has to be adjusted depending on exactly what you need).

How do I get the path of the assembly the code is in?

It's as simple as this:

var dir = AppDomain.CurrentDomain.BaseDirectory;

Apply CSS Style to child elements

This code "div.test th, td, caption {padding:40px 100px 40px 50px;}" applies a rule to all th elements which are contained by a div element with a class named test, in addition to all td elements and all caption elements.

It is not the same as "all td, th and caption elements which are contained by a div element with a class of test". To accomplish that you need to change your selectors:

'>' isn't fully supported by some older browsers (I'm looking at you, Internet Explorer).

div.test th,
div.test td,
div.test caption {
    padding: 40px 100px 40px 50px;

How can I create tests in Android Studio?

I would suggest to use file.

  1. Add a src/androidTest/java directory for the tests (Like Chris starts to explain)

  2. Open file and specify there:

    android {
        compileSdkVersion rootProject.compileSdkVersion
        buildToolsVersion rootProject.buildToolsVersion
        sourceSets {
            androidTest {
                java.srcDirs = ['androidTest/java']
  3. Press "Sync Project with Gradle file" (at the top panel). You should see now a folder "java" (inside "androidTest") is a green color.

  4. Now You are able to create there any test files and execute they.

How do I list one filename per output line in Linux?

Easy, as long as your filenames don't include newlines:

find . -maxdepth 1

If you're piping this into another command, you should probably prefer to separate your filenames by null bytes, rather than newlines, since null bytes cannot occur in a filename (but newlines may):

find . -maxdepth 1 -print0

Printing that on a terminal will probably display as one line, because null bytes are not normally printed. Some programs may need a specific option to handle null-delimited input, such as sort's -z. Your own script similarly would need to account for this.

Bash mkdir and subfolders

To create multiple sub-folders

mkdir -p parentfolder/{subfolder1,subfolder2,subfolder3}

java: How can I do dynamic casting of a variable from one type to another?

I recently felt like I had to do this too, but then found another way which possibly makes my code look neater, and uses better OOP.

I have many sibling classes that each implement a certain method doSomething(). In order to access that method, I would have to have an instance of that class first, but I created a superclass for all my sibling classes and now I can access the method from the superclass.

Below I show two ways alternative ways to "dynamic casting".

// Method 1.
mFragment = getFragmentManager().findFragmentByTag(MyHelper.getName(mUnitNum));
switch (mUnitNum) {
case 0:
    ((MyFragment0) mFragment).sortNames(sortOptionNum);
case 1:
    ((MyFragment1) mFragment).sortNames(sortOptionNum);
case 2:
    ((MyFragment2) mFragment).sortNames(sortOptionNum);

and my currently used method,

// Method 2.
mSuperFragment = (MySuperFragment) getFragmentManager().findFragmentByTag(MyHelper.getName(mUnitNum));

jquery/javascript convert date string to date

If you only need it once, it's overkill to load a plugin.

For a date "dd/mm/yyyy", this works for me:

new Date(, 10),, 5)-1,, 2));

Just invert month and day for mm/dd/yyyy, the syntax is new Date(y,m,d)

Java how to replace 2 or more spaces with single space in string and delete leading and trailing spaces

Try this one.

Sample Code

String str = " hello     there   ";
System.out.println(str.replaceAll("( +)"," ").trim());


hello there

First it will replace all the spaces with single space. Than we have to supposed to do trim String because Starting of the String and End of the String it will replace the all space with single space if String has spaces at Starting of the String and End of the String So we need to trim them. Than you get your desired String.

Differences between Microsoft .NET 4.0 full Framework and Client Profile

Cameron MacFarland nailed it.

I'd like to add that the .NET 4.0 client profile will be included in Windows Update and future Windows releases. Expect most computers to have the client profile, not the full profile. Do not underestimate that fact if you're doing business-to-consumer (B2C) sales.

Builder Pattern in Effective Java

As many already stated here you need to make the class static. Just small addition - if you want, there is a bit different way without static one.

Consider this. Implementing a builder by declaring something like withProperty(value) type setters inside the class and make them return a reference to itself. In this approach, you have a single and an elegant class which is a thread safe and concise.

Consider this:

public class DataObject {

    private String first;
    private String second;
    private String third;

    public String getFirst(){
       return first; 

    public void setFirst(String first){
       this.first = first; 


    public DataObject withFirst(String first){
       this.first = first;
       return this; 

    public DataObject withSecond(String second){
       this.second = second;
       return this; 

    public DataObject withThird(String third){
       this.third = third;
       return this; 

DataObject dataObject = new DataObject()
     .withFirst("first data")
     .withSecond("second data")
     .withThird("third data");

Check it out for more Java Builder examples.

How to tell which commit a tag points to in Git?

So I have a load of release folders, where those folders may be checked out from one of a few different repos, and may be dev, qa or master branches or may be production releases, checked out from a tag, and the tag may be annotated or not. I have a script that will look at the target folder and get be back an answer in the form -. The problem is different versions of git return different status' for a tag checkout.

So I found git show-ref --tags worked initially, except for the annotated tags. However adding -d added a separate entry to the list of tags, one for the tag, the other for the annotation (the annotation commit was identified as ^{} which I stripped out with sed).

So this is the core of my script, for anyone that wants it:-

REPO=`git --git-dir=${TARGET} remote show origin -n | \
         grep "Fetch URL:" | \
         sed -E "s/^.*\/(.*)$/\1/" | \
         sed "s/.git$//"`

TAG=`git --git-dir=${TARGET} show-ref -d --tags | \
         grep \`git --git-dir=${TARGET} show --quiet --format=format:%H HEAD\` | \
         cut -d\  -f2 | \
         cut -d/ -f3 | \
         sed "s/\^{}$//"`

if [ "${TAG}" == "" ] ; then 
  BRANCH=`git --git-dir=${TARGET} show-ref --heads | \
         grep \`git --git-dir=${TARGET} show --quiet --format=format:%H HEAD\` | \
         cut -d\  -f2 | \
         cut -d/ -f3`

DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss") is returning AM time instead of PM time?

Use HH for 24 hour hours format:

DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")

Or the tt format specifier for the AM/PM part:

DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss tt")

Take a look at the custom Date and Time format strings documentation.

PHP Change Array Keys

I did this for an array of objects. Its basically creating new keys in the same array and unsetting the old keys.

public function transform($key, $results)
    foreach($results as $k=>$result)
        if( property_exists($result, $key) )
            $results[$result->$key] = $result;

    return $results;

How to calculate percentage with a SQL statement

This one is working well in MS SQL. It transforms varchar to the result of two-decimal-places-limited float.

Select field1, cast(Try_convert(float,(Count(field2)* 100) / 
Try_convert(float, (Select Count(*) From table1))) as decimal(10,2)) as new_field_name 
From table1 
Group By field1, field2;

JQuery: detect change in input field

Use jquery change event

Description: Bind an event handler to the "change" JavaScript event, or trigger that event on an element.

An example

$("input[type='text']").change( function() {
  // your code

The advantage that .change has over .keypress , .focus , .blur is that .change event will fire only when input has changed

Insert all data of a datagridview to database at once

You have a syntax error Please try the following syntax as given below:

string StrQuery="INSERT INTO tableName VALUES ('" + dataGridView1.Rows[i].Cells[0].Value + "',' " + dataGridView1.Rows[i].Cells[1].Value + "', '" + dataGridView1.Rows[i].Cells[2].Value + "', '" + dataGridView1.Rows[i].Cells[3].Value + "',' " + dataGridView1.Rows[i].Cells[4].Value + "')";

ReactJS call parent method

To do this you pass a callback as a property down to the child from the parent.

For example:

var Parent = React.createClass({

    getInitialState: function() {
        return {
            value: 'foo'

    changeHandler: function(value) {
            value: value

    render: function() {
        return (
                <Child value={this.state.value} onChange={this.changeHandler} />

var Child = React.createClass({
    propTypes: {
        value:      React.PropTypes.string,
        onChange:   React.PropTypes.func
    getDefaultProps: function() {
        return {
            value: ''
    changeHandler: function(e) {
        if (typeof this.props.onChange === 'function') {
    render: function() {
        return (
            <input type="text" value={this.props.value} onChange={this.changeHandler} />

In the above example, Parent calls Child with a property of value and onChange. The Child in return binds an onChange handler to a standard <input /> element and passes the value up to the Parent's callback if it's defined.

As a result the Parent's changeHandler method is called with the first argument being the string value from the <input /> field in the Child. The result is that the Parent's state can be updated with that value, causing the parent's <span /> element to update with the new value as you type it in the Child's input field.

Scheduling recurring task in Android


As mentioned on the javadocs you are better off using a ScheduledThreadPoolExecutor.


Use this class when your use case requires multiple worker threads and the sleep interval is small. How small ? Well, I'd say about 15 minutes. The AlarmManager starts schedule intervals at this time and it seems to suggest that for smaller sleep intervals this class can be used. I do not have data to back the last statement. It is a hunch.


Your service can be closed any time by the VM. Do not use services for recurring tasks. A recurring task can start a service, which is another matter entirely.

BroadcastReciever with AlarmManager

For longer sleep intervals (>15 minutes), this is the way to go. AlarmManager already has constants ( AlarmManager.INTERVAL_DAY ) suggesting that it can trigger tasks several days after it has initially been scheduled. It can also wake up the CPU to run your code.

You should use one of those solutions based on your timing and worker thread needs.

UnicodeEncodeError: 'charmap' codec can't encode characters

For those still getting this error, adding encode("utf-8") to soup will also fix this.

soup = BeautifulSoup(html_doc, 'html.parser').encode("utf-8")

Move the most recent commit(s) to a new branch with Git

If you just need to move all your unpushed commits to a new branch, then you just need to,

  1. create a new branch from the current one :git branch new-branch-name

  2. push your new branch: git push origin new-branch-name

  3. revert your old(current) branch to the last pushed/stable state: git reset --hard origin/old-branch-name

Some people also have other upstreams rather than origin, they should use appropriate upstream

Ajax - 500 Internal Server Error

I think your return string data is very long. so the JSON format has been corrupted. You should change the max size for JSON data in this way :

Open the Web.Config file and paste these lines into the configuration section

      <jsonSerialization maxJsonLength="50000000"/>

Apache VirtualHost and localhost

I am running Ubuntu 16.04 (Xenial Xerus). This is what worked for me:

  1. Open up a terminal and cd to /etc/apache2/sites-available. There you will find a file called 000-default.conf.
  2. Copy that file: cp 000-default.conf example.local.conf
  3. Open that new file (I use Nano; use what you are comfortable with).
  4. You will see a lot of commented lines, which you can delete.
  5. Change <VirtualHost *:80> to <VirtualHost example.local:80>
  6. Change the document root to reflect the location of your files.
  7. Add the following line: ServerName example.local And if you need to, add this line: ServerAlias www.example.local
  8. Save the file and restart Apache: service Apache2 restart

Open a browser and navigate to example.local. You should see your website.

Excel formula to get ranking position

You can use the RANK function in Excel without necessarily sorting the data. Type =RANK(C2,$C$2:$C$7). Excel will find the relative position of the data in C2 and display the answer. Copy the formula through to C7 by dragging the small node at the right end of the cell cursor.

Finding all possible permutations of a given string in python

Here is another approach different from what @Adriano and @illerucis posted. This has a better runtime, you can check that yourself by measuring the time:

def removeCharFromStr(str, index):
    endIndex = index if index == len(str) else index + 1
    return str[:index] + str[endIndex:]

# 'ab' -> a + 'b', b + 'a'
# 'abc' ->  a + bc, b + ac, c + ab
#           a + cb, b + ca, c + ba
def perm(str):
    if len(str) <= 1:
        return {str}
    permSet = set()
    for i, c in enumerate(str):
        newStr = removeCharFromStr(str, i)
        retSet = perm(newStr)
        for elem in retSet:
            permSet.add(c + elem)
    return permSet

For an arbitrary string "dadffddxcf" it took 1.1336 sec for the permutation library, 9.125 sec for this implementation and 16.357 secs for @Adriano's and @illerucis' version. Of course you can still optimize it.

How do I enable EF migrations for multiple contexts to separate databases?

I just bumped into the same problem and I used the following solution (all from Package Manager Console)

PM> Enable-Migrations -MigrationsDirectory "Migrations\ContextA" -ContextTypeName MyProject.Models.ContextA
PM> Enable-Migrations -MigrationsDirectory "Migrations\ContextB" -ContextTypeName MyProject.Models.ContextB

This will create 2 separate folders in the Migrations folder. Each will contain the generated Configuration.cs file. Unfortunately you still have to rename those Configuration.cs files otherwise there will be complaints about having two of them. I renamed my files to ConfigA.cs and ConfigB.cs

EDIT: (courtesy Kevin McPheat) Remember when renaming the Configuration.cs files, also rename the class names and constructors /EDIT

With this structure you can simply do

PM> Add-Migration -ConfigurationTypeName ConfigA
PM> Add-Migration -ConfigurationTypeName ConfigB

Which will create the code files for the migration inside the folder next to the config files (this is nice to keep those files together)

PM> Update-Database -ConfigurationTypeName ConfigA
PM> Update-Database -ConfigurationTypeName ConfigB

And last but not least those two commands will apply the correct migrations to their corrseponding databases.

EDIT 08 Feb, 2016: I have done a little testing with EF7 version 7.0.0-rc1-16348

I could not get the -o|--outputDir option to work. It kept on giving Microsoft.Dnx.Runtime.Common.Commandline.CommandParsingException: Unrecognized command or argument

However it looks like the first time an migration is added it is added into the Migrations folder, and a subsequent migration for another context is automatically put into a subdolder of migrations.

The original names ContextA seems to violate some naming conventions so I now use ContextAContext and ContextBContext. Using these names you could use the following commands: (note that my dnx still works from the package manager console and I do not like to open a separate CMD window to do migrations)

PM> dnx ef migrations add Initial -c "ContextAContext"
PM> dnx ef migrations add Initial -c "ContextBContext"

This will create a model snapshot and a initial migration in the Migrations folder for ContextAContext. It will create a folder named ContextB containing these files for ContextBContext

I manually added a ContextA folder and moved the migration files from ContextAContext into that folder. Then I renamed the namespace inside those files (snapshot file, initial migration and note that there is a third file under the initial migration file ... designer.cs). I had to add .ContextA to the namespace, and from there the framework handles it automatically again.

Using the following commands would create a new migration for each context

PM>  dnx ef migrations add Update1 -c "ContextAContext"
PM>  dnx ef migrations add Update1 -c "ContextBContext"

and the generated files are put in the correct folders.

Python: Remove division decimal

When a number as a decimal it is usually a float in Python.

If you want to remove the decimal and keep it an integer (int). You can call the int() method on it like so...

>>> int(2.0)

However, int rounds down so...

>>> int(2.9)

If you want to round to the nearest integer you can use round:

>>> round(2.9)
>>> round(2.4)

And then call int() on that:

>>> int(round(2.9))
>>> int(round(2.4))

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

Try this:

public partial class Service : ServiceBase
    private Timer timer;
    public Service()

    protected override void OnStart(string[] args)

    private void SetTimer()
        if (timer == null)
            timer = new Timer();
            timer.AutoReset = true;
            timer.Interval = 60000 * Convert.ToDouble(ConfigurationManager.AppSettings["IntervalMinutes"]);
            timer.Elapsed += new ElapsedEventHandler(timer_Elapsed);

    private void timer_Elapsed(object source, System.Timers.ElapsedEventArgs e)
        //Do some thing logic here

    protected override void OnStop()
        // disposed all service objects

Send file using POST from a Python script

Looks like python requests does not handle extremely large multi-part files.

The documentation recommends you look into requests-toolbelt.

Here's the pertinent page from their documentation.

Using multiple property files (via PropertyPlaceholderConfigurer) in multiple projects/modules

You can have multiple <context:property-placeholder /> elements instead of explicitly declaring multiple PropertiesPlaceholderConfigurer beans.

Python Dictionary Comprehension

I really like the @mgilson comment, since if you have a two iterables, one that corresponds to the keys and the other the values, you can also do the following.

keys = ['a', 'b', 'c']
values = [1, 2, 3]
d = dict(zip(keys, values))


d = {'a': 1, 'b': 2, 'c': 3}

How to search a specific value in all tables (PostgreSQL)?

to search every column of every table for a particular value

This does not define how to match exactly.
Nor does it define what to return exactly.


  • Find any row with any column containing the given value in its text representation - as opposed to equaling the given value.
  • Return the table name (regclass) and the tuple ID (ctid), because that's simplest.

Here is a dead simple, fast and slightly dirty way:

CREATE OR REPLACE FUNCTION search_whole_db(_like_pattern text)
  RETURNS TABLE(_tbl regclass, _ctid tid) AS
   FOR _tbl IN
      SELECT c.oid::regclass
      FROM   pg_class c
      JOIN   pg_namespace n ON n.oid = relnamespace
      WHERE  c.relkind = 'r'                           -- only tables
      AND    n.nspname !~ '^(pg_|information_schema)'  -- exclude system schemas
      ORDER BY n.nspname, c.relname
         'SELECT $1, ctid FROM %s t WHERE t::text ~~ %L'
       , _tbl, '%' || _like_pattern || '%')
      USING _tbl;
$func$  LANGUAGE plpgsql;


SELECT * FROM search_whole_db('mypattern');

Provide the search pattern without enclosing %.

Why slightly dirty?

If separators and decorators for the row in text representation can be part of the search pattern, there can be false positives:

  • column separator: , by default
  • whole row is enclosed in parentheses:()
  • some values are enclosed in double quotes "
  • \ may be added as escape char

And the text representation of some columns may depend on local settings - but that ambiguity is inherent to the question, not to my solution.

Each qualifying row is returned once only, even when it matches multiple times (as opposed to other answers here).

This searches the whole DB except for system catalogs. Will typically take a long time to finish. You might want to restrict to certain schemas / tables (or even columns) like demonstrated in other answers. Or add notices and a progress indicator, also demonstrated in another answer.

The regclass object identifier type is represented as table name, schema-qualified where necessary to disambiguate according to the current search_path:

What is the ctid?

You might want to escape characters with special meaning in the search pattern. See:

Update only specific fields in a models.Model

Usually, the correct way of updating certain fields in one or more model instances is to use the update() method on the respective queryset. Then you do something like this:

affected_surveys = Survey.objects.filter(
    # restrict your queryset by whatever fits you
    # ...

This way, you don't need to call save() on your model anymore because it gets saved automatically. Also, the update() method returns the number of survey instances that were affected by your update.

Two arrays in foreach loop

I solved a problem like yours by this way:

foreach(array_keys($idarr) as $i) {
 echo "Student ID: ".$idarr[$i]."<br />";
 echo "Present: ".$presentarr[$i]."<br />";
 echo "Reason: ".$reasonarr[$i]."<br />";
 echo "Mark: ".$markarr[$i]."<br />";

batch script - read line by line

For those with spaces in the path, you are going to want something like this: n.b. It expands out to an absolute path, rather than relative, so if your running directory path has spaces in, these count too.

set SOURCE=path\with spaces\to\my.log
FOR /F "usebackq delims=" %%A IN ("%SOURCE%") DO (
    ECHO %%A

To explain:

(path\with spaces\to\my.log)

Will not parse, because spaces. If it becomes:

("path\with spaces\to\my.log")

It will be handled as a string rather than a file path.

"usebackq delims=" 

See docs will allow the path to be used as a path (thanks to Stephan).

Google Maps API v3: Can I setZoom after fitBounds?

Edit: See Matt Diamond's comment below.

Got it! Try this:

var listener = google.maps.event.addListener(map, "idle", function() { 
  if (map.getZoom() > 16) map.setZoom(16); 

Modify to your needs.

Kotlin - How to correctly concatenate a String

There are various way to concatenate strings in kotlin Example -

a = "Hello" , b= "World"
  1. Using + operator a+b

  2. Using plus() operator

Note - + is internally converted to .plus() method only

In above 2 methods, a new string object is created as strings are immutable. if we want to modify the existing string, we can use StringBuilder

StringBuilder str = StringBuilder("Hello").append("World")

Delete last commit in bitbucket

As others have said, usually you want to use hg backout or git revert. However, sometimes you really want to get rid of a commit.

First, you'll want to go to your repository's settings. Click on the Strip commits link.

Strip commits link in bitbucket settings

Enter the changeset ID for the changeset you want to destroy, and click Preview strip. That will let you see what kind of damage you're about to do before you do it. Then just click Confirm and your commit is no longer history. Make sure you tell all your collaborators what you've done, so they don't accidentally push the offending commit back.

git - Server host key not cached

I suspect that your GIT_SSH environment variable is set to %ProgramFiles(x86)%\putty\plink.exe. For some reason, PLink does not use the .ssh/known_hosts file in your user directory to store the remote hosts keys.

If this is actually your case, and it might be so on purpose if you want to use pageant, you need to use PLink to connect to the host first.

"$GIT_SSH" user@hostname

You should get a similar message

The server's host key is not cached in the registry. You
have no guarantee that the server is the computer you
think it is.
The server's rsa2 key fingerprint is:
ssh-rsa 2048 86:7b:1b:12:85:35:8a:b7:98:b6:d2:97:5e:96:58:1d
If you trust this host, enter "y" to add the key to
PuTTY's cache and carry on connecting.
If you want to carry on connecting just once, without
adding the key to the cache, enter "n".
If you do not trust this host, press Return to abandon the
Store key in cache? (y/n)

Once you have answered y to the question and successfully connected to the remote host, you should be all set. Go ahead and try your push again.

Python 3 string.join() equivalent?

There are method join for string objects:


Git - how delete file from remote repository

Use commands :

git rm /path to file name /

followed by

git commit -m "Your Comment"

git push

your files will get deleted from the repository

Proper MIME media type for PDF files

From Wikipedia Media type,

A media type is composed of a type, a subtype, and optional parameters. As an example, an HTML file might be designated text/html; charset=UTF-8.

Media type consists of top-level type name and sub-type name, which is further structured into so-called "trees".

top-level type name / subtype name [ ; parameters ]

top-level type name / [ tree. ] subtype name [ +suffix ] [ ; parameters ]

All media types should be registered using the IANA registration procedures. Currently the following trees are created: standard, vendor, personal or vanity, unregistered x.


Media types in the standards tree do not use any tree facet (prefix).

type / media type name [+suffix]

Examples: "application/xhtml+xml", "image/png"


Vendor tree is used for media types associated with publicly available products. It uses vnd. facet.

type / vnd. media type name [+suffix] - used in the case of well-known producer

type / vnd. producer's name followed by media type name [+suffix] - producer's name must be approved by IANA

type / vnd. producer's name followed by product's name [+suffix] - producer's name must be approved by IANA

Personal or Vanity tree:

Personal or Vanity tree includes media types created experimentally or as part of products that are not distributed commercially. It uses prs. facet.

type / prs. media type name [+suffix]

Unregistered x. tree:

The "x." tree may be used for media types intended exclusively for use in private, local environments and only with the active agreement of the parties exchanging them. Types in this tree cannot be registered.

According to the previous version of RFC 6838 - obsoleted RFC 2048 (published in November 1996) it should rarely, if ever, be necessary to use unregistered experimental types, and as such use of both "x-" and "x." forms is discouraged. Previous versions of that RFC - RFC 1590 and RFC 1521 stated that the use of "x-" notation for the sub-type name may be used for unregistered and private sub-types, but this recommendation was obsoleted in November 1996.

type / x. media type name [+suffix]

So its clear that the standard type MIME type application/pdf is the appropriate one to use while you should avoid using the obsolete and unregistered x- media type as stated in RFC 2048 and RFC 6838.

Rounding up to next power of 2

For IEEE floats you'd be able to do something like this.

int next_power_of_two(float a_F){
    int f = *(int*)&a_F;
    int b = f << 9 != 0; // If we're a power of two this is 0, otherwise this is 1

    f >>= 23; // remove factional part of floating point number
    f -= 127; // subtract 127 (the bias) from the exponent

    // adds one to the exponent if were not a power of two, 
    // then raises our new exponent to the power of two again.
    return (1 << (f + b)); 

If you need an integer solution and you're able to use inline assembly, BSR will give you the log2 of an integer on the x86. It counts how many right bits are set, which is exactly equal to the log2 of that number. Other processors have similar instructions (often), such as CLZ and depending on your compiler there might be an intrinsic available to do the work for you.

$(window).height() vs $(document).height

AFAIK $(window).height(); returns the height of your window and $(document).height(); returns the height of your document

Expected block end YAML error

The line starting ALREADYEXISTS uses as the closing quote, it should be using '. The open quote on the next line (where the error is reported) is seen as the closing quote, and this mix up is causing the error.

iOS - UIImageView - how to handle UIImage image orientation

You can completely avoid manually doing the transforms and scaling yourself, as suggested by an0 in this answer here:

- (UIImage *)normalizedImage {
    if (self.imageOrientation == UIImageOrientationUp) return self; 

    UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
    [self drawInRect:(CGRect){0, 0, self.size}];
    UIImage *normalizedImage = UIGraphicsGetImageFromCurrentImageContext();
    return normalizedImage;

The documentation for the UIImage methods size and drawInRect explicitly states that they take into account orientation.

How to search in an array with preg_match?

$haystack = array (
   'say hello',
   'hello stackoverflow',
   'hello world',
   'foo bar bas'

$matches  = preg_grep('/hello/i', $haystack);



    [1] => say hello
    [2] => hello stackoverflow
    [3] => hello world

How to Convert datetime value to yyyymmddhhmmss in SQL server?

also this works too

SELECT replace(replace(replace(convert(varchar, getdate(), 120),':',''),'-',''),' ','')

"SSL certificate verify failed" using pip to install packages

One note on the above answers: it is no longer sufficient to add just to the trusted-hosts in the case where you are behind an HTTPS-intercepting proxy (we have zScaler).

I currently have the following in my pip.ini:

trusted-host =

Running pip -v install pkg will give you some hints as to which hosts might need to be added.

Print in new line, java

\n creates a new line in Java. Don't use spaces before or after \n.

Example: printing It creates\na new line outputs

It creates
a new line.

sqlalchemy IS NOT NULL select

In case anyone else is wondering, you can use is_ to generate foo IS NULL:

>>> from sqlalchemy.sql import column
>>> print column('foo').is_(None)
>>> print column('foo').isnot(None)

How can I determine the URL that a local Git repository was originally cloned from?

If you want only the remote URL, or if your are not connected to a network that can reach the remote repo:

git config --get remote.origin.url

If you require full output and you are on a network that can reach the remote repo where the origin resides :

git remote show origin

When using git clone (from GitHub, or any source repository for that matter) the default name for the source of the clone is "origin". Using git remote show will display the information about this remote name. The first few lines should show:

C:\Users\jaredpar\VsVim> git remote show origin
* remote origin
  Fetch URL: [email protected]:jaredpar/VsVim.git
  Push  URL: [email protected]:jaredpar/VsVim.git
  HEAD branch: master
  Remote branches:

If you want to use the value in the script, you would use the first command listed in this answer.

Make a Bash alias that takes a parameter?

Bash alias absolutely does accept parameters. I just added an alias to create a new react app which accepts the app name as a parameter. Here's my process:

Open the bash_profile for editing in nano

nano /.bash_profile

Add your aliases, one per line:

alias gita='git add .'
alias gitc='git commit -m "$@"'
alias gitpom='git push origin master'
alias creact='npx create-react-app "$@"'

note: the "$@" accepts parameters passed in like "creact my-new-app"

Save and exit nano editor

ctrl+o to to write (hit enter); ctrl+x to exit

Tell terminal to use the new aliases in .bash_profile

source /.bash_profile

That's it! You can now use your new aliases

How to solve java.lang.NoClassDefFoundError?

I get NoClassFoundError when classes loaded by the runtime class loader cannot access classes already loaded by the java rootloader. Because the different class loaders are in different security domains (according to java) the jvm won't allow classes already loaded by the rootloader to be resolved in the runtime loader address space.

Run your program with 'java -javaagent:tracer.jar [YOUR java ARGS]'

It produces output showing the loaded class, and the loader env that loaded the class. It's very helpful tracing why a class cannot be resolved.

// From:

import java.lang.instrument.*;

// Premain-Class: ClassLoadTracer

// jar -cvfm tracer.jar ClassLoaderTracer.class

// java -javaagent:tracer.jar  [...]

public class ClassLoadTracer 
    public static void premain(String agentArgs, Instrumentation inst) 
        final out = System.out;
        inst.addTransformer(new ClassFileTransformer() {
            public byte[] transform(ClassLoader loader, String className, Class classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {

                String pd = (null == protectionDomain) ? "null" : protectionDomain.getCodeSource().toString();
                out.println(className + " loaded by " + loader + " at " + new java.util.Date() + " in " + pd);

                // dump stack trace of the thread loading class 

                // we just want the original .class bytes to be loaded!
                // we are not instrumenting it...
                return null;

Finding and removing non ascii characters from an Oracle Varchar2

I had a similar issue and blogged about it here. I started with the regular expression for alpha numerics, then added in the few basic punctuation characters I liked:

select dump(a,1016), a, b
 (select regexp_replace(COLUMN,'[[:alnum:]/''%()> -.:=;[]','') a,
         COLUMN b
  from TABLE)
where a is not null
order by a;

I used dump with the 1016 variant to give out the hex characters I wanted to replace which I could then user in a utl_raw.cast_to_varchar2.

How to sort a collection by date in MongoDB?

Sorting by date doesn't require anything special. Just sort by the desired date field of the collection.

Updated for the 1.4.28 node.js native driver, you can sort ascending on datefield using any of the following ways:

collection.find().sort({datefield: 1}).toArray(function(err, docs) {...});
collection.find().sort('datefield', 1).toArray(function(err, docs) {...});
collection.find().sort([['datefield', 1]]).toArray(function(err, docs) {...});
collection.find({}, {sort: {datefield: 1}}).toArray(function(err, docs) {...});
collection.find({}, {sort: [['datefield', 1]]}).toArray(function(err, docs) {...});

'asc' or 'ascending' can also be used in place of the 1.

To sort descending, use 'desc', 'descending', or -1 in place of the 1.

Python json.loads shows ValueError: Extra data

One-liner for your problem:

data = [json.loads(line) for line in open('tweets.json', 'r')]

Difference between const reference and normal parameter

The difference is more prominent when you are passing a big struct/class.

struct MyData {
    int a,b,c,d,e,f,g,h;
    long array[1234];
void DoWork(MyData md);
void DoWork(const MyData& md);

when you use use 'normal' parameter, you pass the parameter by value and hence creating a copy of the parameter you pass. if you are using const reference, you pass it by reference and the original data is not copied.

in both cases, the original data cannot be modified from inside the function.

In certain cases, the original data might be able to get modified as pointed out by Charles Bailey in his answer.

How do I print a list of "Build Settings" in Xcode project?

Although @dunedin15's fantastic answer has served me well on a number of occasions, it can give inaccurate results for some edge-cases, such as when debugging build settings of a static lib for an Archive build.

As an alternative, a Run Script Build Phase can be easily added to any target to “Log Build Settings” when it's built:

Target's Build Phases section w/ added Log Build Settings script phase

To add, (with the target in question selected) under the Build Phases tab-section click the little ? button a dozen-or-so pixels up-left-ward from the Target Dependencies section, and set the shell to /bin/bash and the command to export.  You'll also probably want to drag the phase upwards so that it happens just after Target Dependencies and before Copy Headers or Compile Sources.  Renaming the phase from “Run Script” to “Log Build Settings” isn't a bad idea.

The result is this incredibly helpful listing of current environment variables used for building:

Build Log output w/ export command's results

Can I change the color of Font Awesome's icon color?

It might a little bit tricky to change the color of font-awesome icons. The simpler method is to add your own class name inside the font-awesome defined classes like this:


And target your custom_defined__class_name in your CSS to change the color to whatever you like.

Specifying trust store information in spring boot

I had the same problem with Spring Boot, Spring Cloud (microservices) and a self-signed SSL certificate. Keystore worked out of the box from application properties, and Truststore didn't.

I ended up keeping both keystore and trustore configuration in, and adding a separate configuration bean for configuring truststore properties with the System.

public class SSLConfig {
    private Environment env;

    private void configureSSL() {
      //set to TLSv1.1 or TLSv1.2
      System.setProperty("https.protocols", "TLSv1.1");

      //load the '' and
      //'' from
      System.setProperty("", env.getProperty("")); 

How can I get the current PowerShell executing file?

A short demonstration of @gregmac's (excellent and detailed) answer, which essentially recommends $PSCommandPath as the only reliable command to return the currently running script where Powershell 3.0 and above is used.

Here I show returning either the full path or just the file name.


$PSCommandPath  # Full Path 
Split-Path -Path $PSCommandPath -Leaf  # File Name only

function main () {
  'Within a function:'
  Split-Path -Path $PSCommandPath -Leaf



PS> .\Test.ps1

Within a function:

Running a single test from unittest.TestCase via the command line

TL;DR: This would very likely work:

python mypkg/tests/ MyCase.testItIsHot

The explanation:

  • The convenient way

      python mypkg/tests/ MyCase.testItIsHot

    would work, but its unspoken assumption is you already have this conventional code snippet inside (typically at the end of) your test file.

    if __name__ == "__main__":
  • The inconvenient way

      python -m unittest mypkg.tests.test_module.TestClass.test_method

    would always work, without requiring you to have that if __name__ == "__main__": unittest.main() code snippet in your test source file.

So why is the second method considered inconvenient? Because it would be a pain in the <insert one of your body parts here> to type that long, dot-delimited path by hand. While in the first method, the mypkg/tests/ part can be auto-completed, either by a modern shell, or by your editor.

DATEDIFF function in Oracle

In Oracle, you can simply subtract two dates and get the difference in days. Also note that unlike SQL Server or MySQL, in Oracle you cannot perform a select statement without a from clause. One way around this is to use the builtin dummy table, dual:

SELECT TO_DATE('2000-01-02', 'YYYY-MM-DD') -  
       TO_DATE('2000-01-01', 'YYYY-MM-DD') AS DateDiff
FROM   dual

nvm keeps "forgetting" node in new terminal session

Alias to node itself to avoid updating the default alias along with node version updates later on.

nvm alias default node

Iterate through Nested JavaScript Objects

Here is a concise breadth-first iterative solution, which I prefer to recursion:

const findCar = function(car) {
    const carSearch = [cars];

      while(carSearch.length) {
          let item = carSearch.shift();
          if (item.label === car) return true;

      return false;

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

$(document.body) is using the global reference document to get a reference to the body, whereas $('body') is a selector in which jQuery will get the reference to the <body> element on the document.

No major difference that I can see, not any noticeable performance gain from one to the other.

Make multiple-select to adjust its height to fit options without scroll bar

Using the size attribute is the most practical solution, however there are quirks when it is applied to select elements with only two or three options.

  • Setting the size attribute value to "0" or "1" will mostly render a default select element (dropdown).
  • Setting the size attribute to a value greater than "1" will mostly render a selection list with a height capable of displaying at least four items. This also applies to lists with only two or three items, leading to unintended white-space.

Simple JavaScript can be used to set the size attribute to the correct value automatically, e.g. see this fiddle.

$(function() {
    $("#autoheight").attr("size", parseInt($("#autoheight option").length)); 

As mentioned above, this solution does not solve the issue when there are only two or three options.

twig: IF with multiple conditions

If I recall correctly Twig doesn't support || and && operators, but requires or and and to be used respectively. I'd also use parentheses to denote the two statements more clearly although this isn't technically a requirement.

{%if ( fields | length > 0 ) or ( trans_fields | length > 0 ) %}


Expressions can be used in {% blocks %} and ${ expressions }.

Operator    Description
==          Does the left expression equal the right expression?
+           Convert both arguments into a number and add them.
-           Convert both arguments into a number and substract them.
*           Convert both arguments into a number and multiply them.
/           Convert both arguments into a number and divide them.
%           Convert both arguments into a number and calculate the rest of the integer division.
~           Convert both arguments into a string and concatenate them.
or          True if the left or the right expression is true.
and         True if the left and the right expression is true.
not         Negate the expression.

For more complex operations, it may be best to wrap individual expressions in parentheses to avoid confusion:

{% if (foo and bar) or (fizz and (foo + bar == 3)) %}

How do I link object files in C? Fails with "Undefined symbols for architecture x86_64"

The existing answers already cover the "how", but I just wanted to elaborate on the "what" and "why" for others who might be wondering.

What a compiler (gcc) does: The term "compile" is a bit of an overloaded term because it is used at a high-level to mean "convert source code to a program", but more technically means to "convert source code to object code". A compiler like gcc actually performs two related, but arguably distinct functions to turn your source code into a program: compiling (as in the latter definition of turning source to object code) and linking (the process of combining the necessary object code files together into one complete executable).

The original error that you saw is technically a "linking error", and is thrown by "ld", the linker. Unlike (strict) compile-time errors, there is no reference to source code lines, as the linker is already in object space.

By default, when gcc is given source code as input, it attempts to compile each and then link them all together. As noted in the other responses, it's possible to use flags to instruct gcc to just compile first, then use the object files later to link in a separate step. This two-step process may seem unnecessary (and probably is for very small programs) but it is very important when managing a very large program, where compiling the entire project each time you make a small change would waste a considerable amount of time.

What can lead to "IOError: [Errno 9] Bad file descriptor" during os.system()?

You can get this error if you use wrong mode when opening the file. For example:

    with open(output, 'wb') as output_file:

In that code, I want to read the file, but I use mode wb instead of r or r+

Check if input is integer type in C

There are several problems with using scanf with the %d conversion specifier to do this:

  1. If the input string starts with a valid integer (such as "12abc"), then the "12" will be read from the input stream and converted and assigned to num, and scanf will return 1, so you'll indicate success when you (probably) shouldn't;

  2. If the input string doesn't start with a digit, then scanf will not read any characters from the input stream, num will not be changed, and the return value will be 0;

  3. You don't specify if you need to handle non-decimal formats, but this won't work if you have to handle integer values in octal or hexadecimal formats (0x1a). The %i conversion specifier handles decimal, octal, and hexadecimal formats, but you still have the first two problems.

First of all, you'll need to read the input as a string (preferably using fgets). If you aren't allowed to use atoi, you probably aren't allowed to use strtol either. So you'll need to examine each character in the string. The safe way to check for digit values is to use the isdigit library function (there are also the isodigit and isxdigit functions for checking octal and hexadecimal digits, respectively), such as

while (*input && isdigit(*input))

(if you're not even allowed to use isdigit, isodigit, or isxdigit, then slap your teacher/professor for making the assignment harder than it really needs to be).

If you need to be able to handle octal or hex formats, then it gets a little more complicated. The C convention is for octal formats to have a leading 0 digit and for hex formats to have a leading 0x. So, if the first non-whitespace character is a 0, you have to check the next character before you can know which non-decimal format to use.

The basic outline is

  1. If the first non-whitespace character is not a '-', '+', '0', or non-zero decimal digit, then this is not a valid integer string;
  2. If the first non-whitespace character is '-', then this is a negative value, otherwise we assume a positive value;
  3. If the first character is '+', then this is a positive value;
  4. If the first non-whitespace and non-sign character is a non-zero decimal digit, then the input is in decimal format, and you will use isdigit to check the remaining characters;
  5. If the first non-whitespace and non-sign character is a '0', then the input is in either octal or hexadecimal format;
  6. If the first non-whitespace and non-sign character was a '0' and the next character is a digit from '0' to '7', then the input is in octal format, and you will use isodigit to check the remaining characters;
  7. If the first non-whitespace and non-sign character was a 0 and the second character is x or X, then the input is in hexadecimal format and you will use isxdigit to check the remaining characters;
  8. If any of the remaining characters do not satisfy the check function specified above, then this is not a valid integer string.

PHP - get base64 img string decode and save as jpg (resulting empty image )

AFAIK, You have to use image function imagecreatefromstring, imagejpeg to create the images.

$imageData = base64_decode($imageData);
$source = imagecreatefromstring($imageData);
$rotate = imagerotate($source, $angle, 0); // if want to rotate the image
$imageSave = imagejpeg($rotate,$imageName,100);

Hope this will help.


$imageDataEncoded = base64_encode(file_get_contents('sample.png'));
$imageData = base64_decode($imageDataEncoded);
$source = imagecreatefromstring($imageData);
$angle = 90;
$rotate = imagerotate($source, $angle, 0); // if want to rotate the image
$imageName = "hello1.png";
$imageSave = imagejpeg($rotate,$imageName,100);

So Following is the php part of your program .. NOTE the change with comment Change is here

    $uploadedPhotos = array('photo_1','photo_2','photo_3','photo_4');
     foreach ($uploadedPhotos as $file) {
         $imageData = base64_decode($this->input->post($file)); // <-- **Change is here for variable name only**
         $photo = imagecreatefromstring($imageData); // <-- **Change is here**

        /* Set name of the photo for show in the form */
        /*set time of the upload*/
         $datetime_upload = $this->session->userdata('uploading_on_datetime',true);

        /* create temp dir with time and user id */
        $new_dir = 'temp/user_'.$this->session->userdata('user_id',true).'_on_'.$datetime_upload.'/';
        /* move uploaded file with new name */
        // @file_put_contents( $new_dir.$file.'.jpg',imagejpeg($photo));
        imagejpeg($photo,$new_dir.$file.'.jpg',100); // <-- **Change is here**


Creating a list of objects in Python

To fill a list with seperate instances of a class, you can use a for loop in the declaration of the list. The * multiply will link each copy to the same instance.

instancelist = [ MyClass() for i in range(29)]

and then access the instances through the index of the list.

instancelist[5].attr1 = 'whamma'

How can I convert a dictionary into a list of tuples?

By keys() and values() methods of dictionary and zip.

zip will return a list of tuples which acts like an ordered dictionary.


>>> d = { 'a': 1, 'b': 2, 'c': 3 }
>>> zip(d.keys(), d.values())
[('a', 1), ('c', 3), ('b', 2)]
>>> zip(d.values(), d.keys())
[(1, 'a'), (3, 'c'), (2, 'b')]

Difference between declaring variables before or in loop?

It's an interesting question. From my experience there is an ultimate question to consider when you debate this matter for a code:

Is there any reason why the variable would need to be global?

It makes sense to only declare the variable once, globally, as opposed to many times locally, because it is better for organizing the code and requires less lines of code. However, if it only needs to be declared locally within one method, I would initialize it in that method so it is clear that the variable is exclusively relevant to that method. Be careful not to call this variable outside the method in which it is initialized if you choose the latter option--your code won't know what you're talking about and will report an error.

Also, as a side note, don't duplicate local variable names between different methods even if their purposes are near-identical; it just gets confusing.

Remove URL parameters without refreshing page

None of these solutions really worked for me, here is a IE11-compatible function that can also remove multiple parameters:

* Removes URL parameters
* @param removeParams - param array
function removeURLParameters(removeParams) {
  const deleteRegex = new RegExp(removeParams.join('=|') + '=')

  const params ='&')
  let search = []
  for (let i = 0; i < params.length; i++) if (deleteRegex.test(params[i]) === false) search.push(params[i])

  window.history.replaceState({}, document.title, location.pathname + (search.length ? '?' + search.join('&') : '') + location.hash)

removeURLParameters(['param1', 'param2'])

Javascript Cookie with no expiration date

YOU JUST CAN'T. There's no exact code to use for setting a forever cookie but an old trick will do, like current time + 10 years.

Just a note that any dates beyond January 2038 will doomed you for the cookies (32-bit int) will be deleted instantly. Wish for a miracle that that will be fixed in the near future. For 64-bit int, years around 2110 will be safe. As time goes by, software and hardware will change and may never adapt to older ones (the things we have now) so prepare the now for the future.

See Year 2038 problem

How to secure RESTful web services?

If choosing between OAuth versions, go with OAuth 2.0.

OAuth bearer tokens should only be used with a secure transport.

OAuth bearer tokens are only as secure or insecure as the transport that encrypts the conversation. HTTPS takes care of protecting against replay attacks, so it isn't necessary for the bearer token to also guard against replay.

While it is true that if someone intercepts your bearer token they can impersonate you when calling the API, there are plenty of ways to mitigate that risk. If you give your tokens a long expiration period and expect your clients to store the tokens locally, you have a greater risk of tokens being intercepted and misused than if you give your tokens a short expiration, require clients to acquire new tokens for every session, and advise clients not to persist tokens.

If you need to secure payloads that pass through multiple participants, then you need something more than HTTPS/SSL, since HTTPS/SSL only encrypts one link of the graph. This is not a fault of OAuth.

Bearer tokens are easy to for clients to obtain, easy for clients to use for API calls and are widely used (with HTTPS) to secure public facing APIs from Google, Facebook, and many other services.

What are the differences between LDAP and Active Directory?

Active Directory isn't just an implementation of LDAP by Microsoft, that is only a small part of what AD is. Active Directory is (in an overly simplified way) a service that provides LDAP based authentication with Kerberos based Authorization.

Of course their LDAP and Kerberos implementations in AD are not exactly 100% interoperable with other LDAP/Kerberos implementations...

How to convert an Array to a Set in Java

There has been a lot of great answers already, but most of them won't work with array of primitives (like int[], long[], char[], byte[], etc.)

In Java 8 and above, you can box the array with:

Integer[] boxedArr =[]::new);

Then convert to set using stream:


Reading data from DataGridView in C#

 private void HighLightGridRows()
     for (int i = 0; i < dtgvAppSettings.Rows.Count; i++)
         String key = dtgvAppSettings.Rows[i].Cells["Key"].Value.ToString();
         if (key.ToLower().Contains("applicationpath") == true)
             dtgvAppSettings.Rows[i].DefaultCellStyle.BackColor = Color.Yellow;

Is there a performance difference between i++ and ++i in C?

I have been reading through most of the answers here and many of the comments, and I didn't see any reference to the one instance that I could think of where i++ is more efficient than ++i (and perhaps surprisingly --i was more efficient than i--). That is for C compilers for the DEC PDP-11!

The PDP-11 had assembly instructions for pre-decrement of a register and post-increment, but not the other way around. The instructions allowed any "general-purpose" register to be used as a stack pointer. So if you used something like *(i++) it could be compiled into a single assembly instruction, while *(++i) could not.

This is obviously a very esoteric example, but it does provide the exception where post-increment is more efficient(or I should say was, since there isn't much demand for PDP-11 C code these days).

How to include js file in another js file?

It is not possible directly. You may as well write some preprocessor which can handle that.

If I understand it correctly then below are the things that can be helpful to achieve that:

  • Use a pre-processor which will run through your JS files for example looking for patterns like "@import somefile.js" and replace them with the content of the actual file. Nicholas Zakas(Yahoo) wrote one such library in Java which you can use (

  • If you are using Ruby on Rails then you can give Jammit asset packaging a try, it uses assets.yml configuration file where you can define your packages which can contain multiple files and then refer them in your actual webpage by the package name.

  • Try using a module loader like RequireJS or a script loader like LabJs with the ability to control the loading sequence as well as taking advantage of parallel downloading.

JavaScript currently does not provide a "native" way of including a JavaScript file into another like CSS ( @import ), but all the above mentioned tools/ways can be helpful to achieve the DRY principle you mentioned. I can understand that it may not feel intuitive if you are from a Server-side background but this is the way things are. For front-end developers this problem is typically a "deployment and packaging issue".

Hope it helps.

How can I reload .emacs after changing it?

You can use the command load-file (M-x load-file, then press return twice to accept the default filename, which is the current file being edited).

You can also just move the point to the end of any sexp and press C-xC-e to execute just that sexp. Usually it's not necessary to reload the whole file if you're just changing a line or two.

Purge or recreate a Ruby on Rails database

From the command line run

rake db:migrate:reset

How to match, but not capture, part of a regex?

The only way not to capture something is using look-around assertions:


Because even with non-capturing groups (?:…) the whole regular expression captures their matched contents. But this regular expression matches only apple or banana if it’s preceded by 123- and followed by -456, or it matches the empty string if it’s preceded by 123- and followed by 456.

|Lookaround  |    Name      |        What it Does                       |
|(?=foo)     |   Lookahead  | Asserts that what immediately FOLLOWS the |
|            |              |  current position in the string is foo    |
|(?<=foo)    |   Lookbehind | Asserts that what immediately PRECEDES the|
|            |              |  current position in the string is foo    |
|(?!foo)     |   Negative   | Asserts that what immediately FOLLOWS the |
|            |   Lookahead  |  current position in the string is NOT foo|
|(?<!foo)    |   Negative   | Asserts that what immediately PRECEDES the|
|            |   Lookbehind |  current position in the string is NOT foo|

How to use the ProGuard in Android Studio?

NB.: Now instead of

runProguard false

you'll need to use

minifyEnabled false

JavaScript: Passing parameters to a callback function

Use curried function as in this simple example.

const BTN = document.querySelector('button')_x000D_
const RES = document.querySelector('p')_x000D_
const changeText = newText => () => {_x000D_
  RES.textContent = newText_x000D_
BTN.addEventListener('click', changeText('Clicked!'))
<p>Not clicked<p>

Change one value based on another value in pandas

df['FirstName']=df['ID'].apply(lambda x: 'Matt' if x==103 else '')
df['LastName']=df['ID'].apply(lambda x: 'Jones' if x==103 else '')

Test if registry value exists

This works for me:

Function Test-RegistryValue 
    param($regkey, $name)
    $exists = Get-ItemProperty "$regkey\$name" -ErrorAction SilentlyContinue
    Write-Host "Test-RegistryValue: $exists"
    if (($exists -eq $null) -or ($exists.Length -eq 0))
        return $false
        return $true

Jboss server error : Failed to start service jboss.deployment.unit."jbpm-console.war"

I had a similar issue, my error was:

Caused by: java.lang.ClassNotFoundException:org.glassfish.jersey.servlet.ServletContainer from [Module "deployment.RESTful_Services_CRUD.war:main" from Service Module Loader]

I use jboss and glassfish so I changed the web.xml to the following:


Instead of:


Hope this work for you.

Adding space/padding to a UILabel

Similar to other answers, but with a func class to setup the padding dinamically:

class UILabelExtendedView: UILabel
    var topInset: CGFloat = 4.0
    var bottomInset: CGFloat = 4.0
    var leftInset: CGFloat = 8.0
    var rightInset: CGFloat = 8.0

    override func drawText(in rect: CGRect)
        let insets: UIEdgeInsets = UIEdgeInsets(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
        super.drawText(in: UIEdgeInsetsInsetRect(rect, insets))

    override public var intrinsicContentSize: CGSize
        var contentSize = super.intrinsicContentSize
        contentSize.height += topInset + bottomInset
        contentSize.width += leftInset + rightInset
        return contentSize

    func setPadding(top: CGFloat, left: CGFloat, bottom: CGFloat, right: CGFloat){
        self.topInset = top
        self.bottomInset = bottom
        self.leftInset = left
        self.rightInset = right
        let insets: UIEdgeInsets = UIEdgeInsets(top: top, left: left, bottom: bottom, right: right)
        super.drawText(in: UIEdgeInsetsInsetRect(self.frame, insets))

pthread function from a class

The above answers are good, but in my case, 1st approach that converts the function to be a static didn't work. I was trying to convert exiting code to move into thread function but that code had lots to references to non-static class members already. The second solution of encapsulating into C++ object works, but has 3-level wrappers to run a thread.

I had an alternate solution that uses existing C++ construct - 'friend' function, and it worked perfect for my case. An example of how I used 'friend' (will use the above same example for names showing how it can be converted into a compact form using friend)

    class MyThreadClass
       MyThreadClass() {/* empty */}
       virtual ~MyThreadClass() {/* empty */}

       bool Init()
          return (pthread_create(&_thread, NULL, &ThreadEntryFunc, this) == 0);

       /** Will not return until the internal thread has exited. */
       void WaitForThreadToExit()
          (void) pthread_join(_thread, NULL);

       //our friend function that runs the thread task
       friend void* ThreadEntryFunc(void *);

       pthread_t _thread;

    //friend is defined outside of class and without any qualifiers
    void* ThreadEntryFunc(void *obj_param) {
    MyThreadClass *thr  = ((MyThreadClass *)obj_param); 

    //access all the members using thr->

    return NULL;

Ofcourse, we can use boost::thread and avoid all these, but I was trying to modify the C++ code to not use boost (the code was linking against boost just for this purpose)

How to set focus on a view when a layout is created and displayed?

Set these lines to OnResume as well and make sure if focusableInTouch is set to true while you initialize your controls



Can I set a breakpoint on 'memory access' in GDB?

What you're looking for is called a watchpoint.


(gdb) watch foo: watch the value of variable foo

(gdb) watch *(int*)0x12345678: watch the value pointed by an address, casted to whatever type you want

(gdb) watch a*b + c/d: watch an arbitrarily complex expression, valid in the program's native language

Watchpoints are of three kinds:

  • watch: gdb will break when a write occurs
  • rwatch: gdb will break wnen a read occurs
  • awatch: gdb will break in both cases

You may choose the more appropriate for your needs.

For more information, check this out.

How can I do division with variables in a Linux shell?

Referencing Bash Variables Requires Parameter Expansion

The default shell on most Linux distributions is Bash. In Bash, variables must use a dollar sign prefix for parameter expansion. For example:

expr $x / $y

Of course, Bash also has arithmetic operators and a special arithmetic expansion syntax, so there's no need to invoke the expr binary as a separate process. You can let the shell do all the work like this:

x=20; y=5
echo $((x / y))

How to change folder with git bash?

Simply type cd then copy and paste the file path.

Example of changing directory:

example of changing directory

Get LatLng from Zip Code - Google Maps API

Just a hint: zip codes are not worldwide unique so this is worth to provide country ISO code in the request (

e.g looking for coordinates of polish (iso code PL) zipcode 01-210:,PL

how to obtain user country code?

if you would like to get your user country info based on IP address there are services for it, e.g you can do GET request on:

Where does Internet Explorer store saved passwords?

No guarantee, but I suspect IE uses the older Protected Storage API.

Iterating over Numpy matrix rows to apply a function each?

Here's my take if you want to try using multiprocesses to process each row of numpy array,

from multiprocessing import Pool
import numpy as np

def my_function(x):
    pass     # do something and return something

if __name__ == '__main__':    
    X = np.arange(6).reshape((3,2))
    pool = Pool(processes = 4)
    results =, map(lambda x: x, X))
    pool.join() take in a function and an iterable.
I used 'map' function to create an iterator over each rows of the array.
Maybe there's a better to create the iterable though.

What is "with (nolock)" in SQL Server?

The simplest answer is a simple question - do you need your results to be repeatable? If yes then NOLOCKS is not appropriate under any circumstances

If you don't need repeatability then nolocks may be useful, especially if you don't have control over all processes connecting to the target database.

Hive ParseException - cannot recognize input near 'end' 'string'

I was using /Date=20161003 in the folder path while doing an insert overwrite and it was failing. I changed it to /Dt=20161003 and it worked

Java 8: Lambda-Streams, Filter by Method with Exception

If you don't mind using 3rd party libraries, AOL's cyclops-react lib, disclosure::I am a contributor, has a ExceptionSoftener class that can help here.


How to exit from ForEach-Object in PowerShell

I found this question while looking for a way to have fine grained flow control to break from a specific block of code. The solution I settled on wasn't mentioned...

Using labels with the break keyword

From: about_break

A Break statement can include a label that lets you exit embedded loops. A label can specify any loop keyword, such as Foreach, For, or While, in a script.

Here's a simple example

:myLabel for($i = 1; $i -le 2; $i++) {
        Write-Host "Iteration: $i"
        break myLabel

Write-Host "After for loop"

# Results:
# Iteration: 1
# After for loop

And then a more complicated example that shows the results with nested labels and breaking each one.

:outerLabel for($outer = 1; $outer -le 2; $outer++) {

    :innerLabel for($inner = 1; $inner -le 2; $inner++) {
        Write-Host "Outer: $outer / Inner: $inner"
        #break innerLabel
        #break outerLabel

    Write-Host "After Inner Loop"

Write-Host "After Outer Loop"

# Both breaks commented out
# Outer: 1 / Inner: 1
# Outer: 1 / Inner: 2
# After Inner Loop
# Outer: 2 / Inner: 1
# Outer: 2 / Inner: 2
# After Inner Loop
# After Outer Loop

# break innerLabel Results
# Outer: 1 / Inner: 1
# After Inner Loop
# Outer: 2 / Inner: 1
# After Inner Loop
# After Outer Loop

# break outerLabel Results
# Outer: 1 / Inner: 1
# After Outer Loop

You can also adapt it to work in other situations by wrapping blocks of code in loops that will only execute once.

:myLabel do {
    1..2 | % {

        Write-Host "Iteration: $_"
        break myLabel

} while ($false)

Write-Host "After do while loop"

# Results:
# Iteration: 1
# After do while loop

Find the max of two or more columns with pandas

@DSM's answer is perfectly fine in almost any normal scenario. But if you're the type of programmer who wants to go a little deeper than the surface level, you might be interested to know that it is a little faster to call numpy functions on the underlying .to_numpy() (or .values for <0.24) array instead of directly calling the (cythonized) functions defined on the DataFrame/Series objects.

For example, you can use ndarray.max() along the first axis.

# Data borrowed from @DSM's post.
df = pd.DataFrame({"A": [1,2,3], "B": [-2, 8, 1]})
   A  B
0  1 -2
1  2  8
2  3  1

df['C'] = df[['A', 'B']].values.max(1)
# Or, assuming "A" and "B" are the only columns, 
# df['C'] = df.values.max(1) 

   A  B  C
0  1 -2  1
1  2  8  8
2  3  1  3 

If your data has NaNs, you will need numpy.nanmax:

df['C'] = np.nanmax(df.values, axis=1)

   A  B  C
0  1 -2  1
1  2  8  8
2  3  1  3 

You can also use numpy.maximum.reduce. numpy.maximum is a ufunc (Universal Function), and every ufunc has a reduce:

df['C'] = np.maximum.reduce(df['A', 'B']].values, axis=1)
# df['C'] = np.maximum.reduce(df[['A', 'B']], axis=1)
# df['C'] = np.maximum.reduce(df, axis=1)

   A  B  C
0  1 -2  1
1  2  8  8
2  3  1  3

enter image description here

np.maximum.reduce and np.max appear to be more or less the same (for most normal sized DataFrames)—and happen to be a shade faster than DataFrame.max. I imagine this difference roughly remains constant, and is due to internal overhead (indexing alignment, handling NaNs, etc).

The graph was generated using perfplot. Benchmarking code, for reference:

import pandas as pd
import perfplot

df_ = pd.DataFrame(np.random.randn(5, 1000))
    setup=lambda n: pd.concat([df_] * n, ignore_index=True),
        lambda df: df.assign(new=df.max(axis=1)),
        lambda df: df.assign(new=df.values.max(1)),
        lambda df: df.assign(new=np.nanmax(df.values, axis=1)),
        lambda df: df.assign(new=np.maximum.reduce(df.values, axis=1)),
    labels=['df.max', 'np.max', 'np.maximum.reduce', 'np.nanmax'],
    n_range=[2**k for k in range(0, 15)],
    xlabel='N (* len(df))',

Python - How do you run a .py file?

Your command should include the url parameter as stated in the script usage comments. The main function has 2 parameters, url and out (which is set to a default value) C:\python23\python "C:\PathToYourScript\" "C:\OptionalOutput\"

How to execute a .bat file from a C# windows form app?

Here is what you are looking for:

Service hangs up at WaitForExit after calling batch file

It's about a question as to why a service can't execute a file, but it shows all the code necessary to do so.

Redirecting new tab on button click.(Response.Redirect) in C#

You have to add following in header:

<script type="text/javascript">
        function fixform() {
            if (opener.document.getElementById("aspnetForm").target != "_blank") return;

            opener.document.getElementById("aspnetForm").target = "";
            opener.document.getElementById("aspnetForm").action = opener.location.href;

Then call fixform() in load your page.

How to find a Java Memory Leak

Questioner here, I have got to say getting a tool that does not take 5 minutes to answer any click makes it a lot easier to find potential memory leaks.

Since people are suggesting several tools ( I only tried visual wm since I got that in the JDK and JProbe trial ) I though I should suggest a free / open source tool built on the Eclipse platform, the Memory Analyzer (sometimes referenced as the SAP memory analyzer) available on .

What is really cool about this tool is that it indexed the heap dump when I first opened it which allowed it to show data like retained heap without waiting 5 minutes for each object (pretty much all operations were tons faster than the other tools I tried).

When you open the dump, the first screen shows you a pie chart with the biggest objects (counting retained heap) and one can quickly navigate down to the objects that are to big for comfort. It also has a Find likely leak suspects which I reccon can come in handy, but since the navigation was enough for me I did not really get into it.

Visual Studio 64 bit?

No! There is no 64-bit version of Visual Studio.

How to know it is not 64-bit: Once you download Visual Studio and click the install button, you will see that the initialization folder it selects automatically is C:\Program Files (x86)\Microsoft Visual Studio 14.0

As per my understanding, all 64-bit programs/applications goes to C:\Program Files and all 32-bit applications goes to C:\Program Files (x86) from Windows 7 onwards.

How to properly compare two Integers in Java?

== will still test object equality. It is easy to be fooled, however:

Integer a = 10;
Integer b = 10;

System.out.println(a == b); //prints true

Integer c = new Integer(10);
Integer d = new Integer(10);

System.out.println(c == d); //prints false

Your examples with inequalities will work since they are not defined on Objects. However, with the == comparison, object equality will still be checked. In this case, when you initialize the objects from a boxed primitive, the same object is used (for both a and b). This is an okay optimization since the primitive box classes are immutable.

How much should a function trust another function

My 2 cents.

This is a loaded question imho. A rule of thumb I use to is see how this function will be called. If the caller is something I have control over then , its ok to assume that it will be called with the right parameters and with proper initialization.

On the other hand if its some client I don't control then it is a good idea to do thorough error checking.

Generate Java classes from .XSD files...?

The well-known JAXB

There is a maven plugin that could do this for you at any build phase you want.

You could do this stuff in both ways: xsd <-> Java

SVG: text inside rect

This is not possible. If you want to display text inside a rect element you should put them both in a group with the text element coming after the rect element ( so it appears on top ).

<svg xmlns="">_x000D_
    <rect x="0" y="0" width="100" height="100" fill="red"></rect>_x000D_
    <text x="0" y="50" font-family="Verdana" font-size="35" fill="blue">Hello</text>_x000D_

Why have header files and .cpp files?

Well, the main reason would be for separating the interface from the implementation. The header declares "what" a class (or whatever is being implemented) will do, while the cpp file defines "how" it will perform those features.

This reduces dependencies so that code that uses the header doesn't necessarily need to know all the details of the implementation and any other classes/headers needed only for that. This will reduce compilation times and also the amount of recompilation needed when something in the implementation changes.

It's not perfect, and you would usually resort to techniques like the Pimpl Idiom to properly separate interface and implementation, but it's a good start.

How to convert a Collection to List?

List list = new ArrayList(coll);

As Erel Segal Halevi says below, if coll is already a list, you can skip step one. But that would depend on the internals of TreeBidiMap.

List list;
if (coll instanceof List)
  list = (List)coll;
  list = new ArrayList(coll);

WooCommerce: Finding the products in database

Update 2020

Products are located mainly in the following tables:

  • wp_posts table with post_type like product (or product_variation),

  • wp_postmeta table with post_id as relational index (the product ID).

  • wp_wc_product_meta_lookup table with product_id as relational index (the post ID) | Allow fast queries on specific product data (since WooCommerce 3.7)

  • wp_wc_order_product_lookuptable with product_id as relational index (the post ID) | Allow fast queries to retrieve products on orders (since WooCommerce 3.7)

Product types, categories, subcategories, tags, attributes and all other custom taxonomies are located in the following tables:

  • wp_terms

  • wp_termmeta

  • wp_term_taxonomy

  • wp_term_relationships - column object_id as relational index (the product ID)

  • wp_woocommerce_termmeta

  • wp_woocommerce_attribute_taxonomies (for product attributes only)

  • wp_wc_category_lookup (for product categories hierarchy only since WooCommerce 3.7)

Product types are handled by custom taxonomy product_type with the following default terms:

  • simple
  • grouped
  • variable
  • external

Some other product types for Subscriptions and Bookings plugins:

  • subscription
  • variable-subscription
  • booking

Since Woocommerce 3+ a new custom taxonomy named product_visibility handle:

  • The product visibility with the terms exclude-from-search and exclude-from-catalog
  • The feature products with the term featured
  • The stock status with the term outofstock
  • The rating system with terms from rated-1 to rated-5

Particular feature: Each product attribute is a custom taxonomy…


getElementById returns null?

There could be many reason why document.getElementById doesn't work

  • You have an invalid ID

    ID and NAME tokens must begin with a letter ([A-Za-z]) and may be followed by any number of letters, digits ([0-9]), hyphens ("-"), underscores ("_"), colons (":"), and periods ("."). (resource: What are valid values for the id attribute in HTML?)

  • you used some id that you already used as <meta> name in your header (e.g. copyright, author... ) it looks weird but happened to me: if your 're using IE take a look at (resource:

  • you're targeting an element inside a frame or iframe. In this case if the iframe loads a page within the same domain of the parent you should target the contentdocument before looking for the element (resource: Calling a specific id inside a frame)

  • you're simply looking to an element when the node is not effectively loaded in the DOM, or maybe it's a simple misspelling

I doubt you used same ID twice or more: in that case document.getElementById should return at least the first element

What does "yield break;" do in C#?

yield break is just a way of saying return for the last time and don't return any value


// returns 1,2,3,4,5
IEnumerable<int> CountToFive()
    yield return 1;
    yield return 2;
    yield return 3;
    yield return 4;
    yield return 5;
    yield break;
    yield return 6;
    yield return 7;
    yield return 8;
    yield return 9;

mysql: SOURCE error 2?

Passing the full path does not error, but if the folders have MySQL spaces it does not recognize the .sql file. I have MySQL 8.0.21 on OS UNIX.