Programs & Examples On #Application variables

Set session variable in laravel

php artisan make:controller SessionController --plain



namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\Http\Requests;
use App\Http\Controllers\Controller;

class SessionController extends Controller {
   public function accessSessionData(Request $request) {
         echo $request->session()->get('my_name');
         echo 'No data in the session';
   public function storeSessionData(Request $request) {
      $request->session()->put('my_name','Ajay kumar');
      echo "Data has been added to session";
   public function deleteSessionData(Request $request) {
      echo "Data has been removed from session.";

And all route:


More Help: How To Set Session In Laravel?

@Resource vs @Autowired

Both of them are equally good. The advantage of using Resource is in future if you want to another DI framework other than spring, your code changes will be much simpler. Using Autowired your code is tightly coupled with springs DI.

Why "no projects found to import"?

In new updated eclipse the option "create project from existing source" is found here, File>New>Project>Android>Android Project from Existing Code. Then browse to root directory.

enter image description here

VB.NET Empty String Array

Not sure why you'd want to, but the C# way would be

string[] newArray = new string[0];

I'm guessing that VB won't be too dissimilar to this.

If you're building an empty array so you can populate it with values later, you really should consider using


and converting it to an array (if you really need it as an array) with


Converting map to struct

I adapt dave's answer, and add a recursive feature. I'm still working on a more user friendly version. For example, a number string in the map should be able to be converted to int in the struct.

package main

import (

func SetField(obj interface{}, name string, value interface{}) error {

    structValue := reflect.ValueOf(obj).Elem()
    fieldVal := structValue.FieldByName(name)

    if !fieldVal.IsValid() {
        return fmt.Errorf("No such field: %s in obj", name)

    if !fieldVal.CanSet() {
        return fmt.Errorf("Cannot set %s field value", name)

    val := reflect.ValueOf(value)

    if fieldVal.Type() != val.Type() {

        if m,ok := value.(map[string]interface{}); ok {

            // if field value is struct
            if fieldVal.Kind() == reflect.Struct {
                return FillStruct(m, fieldVal.Addr().Interface())

            // if field value is a pointer to struct
            if fieldVal.Kind()==reflect.Ptr && fieldVal.Type().Elem().Kind() == reflect.Struct {
                if fieldVal.IsNil() {
                // fmt.Printf("recursive: %v %v\n", m,fieldVal.Interface())
                return FillStruct(m, fieldVal.Interface())


        return fmt.Errorf("Provided value type didn't match obj field type")

    return nil


func FillStruct(m map[string]interface{}, s interface{}) error {
    for k, v := range m {
        err := SetField(s, k, v)
        if err != nil {
            return err
    return nil

type OtherStruct struct {
    Name string
    Age  int64

type MyStruct struct {
    Name string
    Age  int64
    OtherStruct *OtherStruct

func main() {
    myData := make(map[string]interface{})
    myData["Name"]        = "Tony"
    myData["Age"]         = int64(23)
    OtherStruct := make(map[string]interface{})
    myData["OtherStruct"] = OtherStruct
    OtherStruct["Name"]   = "roxma"
    OtherStruct["Age"]    = int64(23)

    result := &MyStruct{}
    err := FillStruct(myData,result)
    fmt.Printf("%v %v\n",result,result.OtherStruct)

force Maven to copy dependencies into target/lib

A simple and elegant solution for the case where one needs to copy the dependencies to a target directory without using any other phases of maven (I found this very useful when working with Vaadin).

Complete pom example:

<project xmlns="" xmlns:xsi=""






Then run mvn process-sources

The jar file dependencies can be found in /target/dependency

How to resume Fragment from BackStack if exists

Step 1: Implement an interface with your activity class

public class AuthenticatedMainActivity extends Activity implements FragmentManager.OnBackStackChangedListener{

    protected void onCreate(Bundle savedInstanceState) {
        FragmentManager fragmentManager = getFragmentManager();           
        fragmentManager.beginTransaction().add(,fragment, "First").addToBackStack(null).commit();

    private void switchFragment(Fragment fragment){            
      FragmentManager fragmentManager = getFragmentManager();
        .replace(, fragment).addToBackStack("Tag").commit();

    public void onBackStackChanged() {
    FragmentManager fragmentManager = getFragmentManager();

    System.out.println("@Class: SummaryUser : onBackStackChanged " 
            + fragmentManager.getBackStackEntryCount());

    int count = fragmentManager.getBackStackEntryCount();

    // when a fragment come from another the status will be zero
    if(count == 0){

        System.out.println("again loading user data");

        // reload the page if user saved the profile data


                    , "Please check your internet connection");

        }else {

  "Refreshing data..."); 


        // IMPORTANT: remove the current fragment from stack to avoid new instance

    }// end if

Step 2: When you call the another fragment add this method:

String backStateName = this.getClass().getName();

FragmentManager fragmentManager = getFragmentManager();

Fragment fragmentGraph = new GraphFragment();
Bundle bundle = new Bundle();
bundle.putString("graphTag",  view.getTag().toString());

.replace(, fragmentGraph)

Mapping list in Yaml to list of objects in Spring Boot

The reason must be somewhere else. Using only Spring Boot 1.2.2 out of the box with no configuration, it Just Works. Have a look at this repo - can you get it to break?

Are you sure the YAML file looks exactly the way you pasted? No extra whitespace, characters, special characters, mis-indentation or something of that sort? Is it possible you have another file elsewhere in the search path that is used instead of the one you're expecting?

How to get a JavaScript object's class?

I suggest using

Object.defineProperty(Object.prototype, "getClass", {
    value: function() {

var x = new DOMParser();
console.log(x.getClass()); // `DOMParser'

var y = new Error("");
console.log(y.getClass()); // `Error'

How to send string from one activity to another?

In order to insert the text from activity2 to activity1, you first need to create a visit function in activity2.

public void visitactivity1()
    Intent i = new Intent(this, activity1.class);
    i.putExtra("key", message);

After creating this function, you need to call it from your onCreate() function of activity2:


Next, go on to the activity1 Java file. In its onCreate() function, create a Bundle object, fetch the earlier message via its key through this object, and store it in a String.

    Bundle b = getIntent().getExtras();
    String message = b.getString("key", ""); // the blank String in the second parameter is the default value of this variable. In case the value from previous activity fails to be obtained, the app won't crash: instead, it'll go with the default value of an empty string

Now put this element in a TextView or EditText, or whichever layout element you prefer using the setText() function.

How can you undo the last git add?

You can use git reset. This will 'unstage' all the files you've added after your last commit.

If you want to unstage only some files, use git reset -- <file 1> <file 2> <file n>.

Also it's possible to unstage some of the changes in files by using git reset -p.

pass post data with window.location.href

Short answer: no. window.location.href is not capable of passing POST data.

Somewhat more satisfying answer: You can use this function to clone all your form data and submit it.

var submitMe = document.createElement("form");
submitMe.action = "YOUR_URL_HERE"; // Remember to change me
submitMe.method = "post";
submitMe.enctype = "multipart/form-data";
var nameJoiner = "_";
// ^ The string used to join form name and input name
//   so that you can differentiate between forms when
//   processing the data server-side.
submitMe.importFields = function(form){
    for(k in form.elements){
        if(input = form.elements[k]){
                var output = input.cloneNode(true);
       = + nameJoiner +;
  • Do submitMe.importFields(form_element); for each of the three forms you want to submit.
  • This function will add each form's name to the names of its child inputs (If you have an <input name="email"> in <form name="login">, the submitted name will be login_name.
  • You can change the nameJoiner variable to something other than _ so it doesn't conflict with your input naming scheme.
  • Once you've imported all the necessary forms, do submitMe.submit();

getting the reason why websockets closed with close code 1006

I've got the error while using Chrome as client and golang gorilla websocket as server under nginx proxy

And sending just some "ping" message from server to client every x second resolved problem

Decoding UTF-8 strings in Python

It's an encoding error - so if it's a unicode string, this ought to fix it:


If it's a plain string, you'll need an extra step:


Both of these will give you a unicode string.

By the way - to discover how a piece of text like this has been mangled due to encoding issues, you can use chardet:

>>> import chardet
>>> chardet.detect(u"And the Hip’s coming, too")
{'confidence': 0.5, 'encoding': 'windows-1252'}

How to clear Flutter's Build cache?

I tried flutter clean and that didn't work for me. Then I went to wipe the emulator's data and voila, the cached issue was gone. If you have Android Studio you can launch the AVD Manager by following this Create and Manage virtual machine. Otherwise you can wipe the emulator's data using the emulator.exe command line that's included in the android SDK. Simply follow this instructions here Start the emulator from the command line.

How to pass a single object[] to a params object[]

You need to encapsulate it into another object[] array, like this:

Foo(new Object[] { new object[]{ (object)"1", (object)"2" }});

What is CDATA in HTML?

CDATA is Obsolete.

Note that CDATA sections should not be used within HTML; they only work in XML.

So do not use it in HTML 5.

Screenshot from MDN

CSS to line break before/after a particular `inline-block` item

You are not interested in a lot of "solutions" to your problem. I do not think there really is a good way to do what you want to do. Anything you insert using :after and content has exactly the same syntactic and semantic validity it would have done if you had just written it in there yourself.

The tools CSS provide work. You should just float the lis and then clear: left when you want to start a new line, as you have mentioned:

See an example:

Selecting empty text input using jQuery

Building on @James Wiseman's answer, I am using this:

    blank: function(el){
        return $(el).val().match(/^\s*$/);

This will catch inputs which contain only whitespace in addition to those which are 'truly' empty.


printf format specifiers for uint32_t and size_t


#include <inttypes.h>

printf("i [ %zu ] k [ %"PRIu32" ]\n", i, k);

The z represents an integer of length same as size_t, and the PRIu32 macro, defined in the C99 header inttypes.h, represents an unsigned 32-bit integer.

Best way to get application folder path

this one System.IO.Path.GetDirectory(Application.ExecutablePath) changed to System.IO.Path.GetDirectoryName(Application.ExecutablePath)

C++/CLI Converting from System::String^ to std::string

This worked for me:

#include <stdlib.h>
#include <string.h>
#include <msclr\marshal_cppstd.h>
using namespace msclr::interop;
System::String^ clrString = (TextoDeBoton);
std::string stdString = marshal_as<std::string>(clrString); //String^ to std
//System::String^ myString = marshal_as<System::String^>(MyBasicStirng); //std to String^
prueba.CopyInfo(stdString); //MyMethod
//Where: String^ = TextoDeBoton;
//and stdString is a "normal" string;

Tried to Load Angular More Than Once

Another case is with Webpack which concating angular into the bundle.js, beside the angular that is loaded from index.html <script> tag.

this was because we used explicit importing of angular in many files:

define(['angular', ...], function(angular, ...){

so, webpack decided to bundle it too. cleaning all of those into:

define([...], function(...){

was fixing Tried to Load Angular More Than Once for once and all.

Access props inside quotes in React JSX

Here is the Best Option for Dynamic className or Props , just do some concatenation like we do in Javascript.

        "badge " +
        (this.props.value ? "badge-primary " : "badge-danger ") +
        " m-4"

How to format date with hours, minutes and seconds when using jQuery UI Datepicker?

I added this code

<input class="form-control input-small hasDatepicker" id="datepicker6" name="expire_date" type="text" value="2018-03-17 00:00:00">

<script src="/assets/js/datepicker/bootstrap-datepicker.js"></script>
        $(document).ready(function() {
                isRTL: true,
                dateFormat: "yy/mm/dd 23:59:59",
                changeMonth: true,
                changeYear: true


Regular Expression for password validation

Update to Justin answer above. if you want to use it using Data Annotation in MVC you can do as follow

[RegularExpression(@"^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[^\da-zA-Z]).{8,15}$", ErrorMessage = "Password must be between 6 and 20 characters and contain one uppercase letter, one lowercase letter, one digit and one special character.")]

Dark color scheme for Eclipse

Some people posted options for Linux and Mac, and the Windows (free) equivalent is, if you can deal with it globally:

Set Windows desktop appearance theme window background color. You can keep current/desired theme, just modify the background color of windows. By default, it is set to white. I change it to a shade of grey. I tried dark grey and black before, but then you have to change text font colors globally, and all that's painful.

But a simple shade of grey as background does the trick globally, works with any color text font as long as the shade of grey is not too dark.

It's not the best solution for all editors/IDEs, as I prefer black, but it's the next best free & global workaround on Windows.

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

You can access column name specifically like this too if you don't want to loop through all columns:


How to get a vCard (.vcf file) into Android contacts from website

This can be used to download the file to your SD card Tested with Android version 2.3.3 and 4.0.3

======= php =========================

     // this php file (example saved as name is vCardDL.php) is placed in my html subdirectory
     header('Content-Type: application/octet-stream');
     // the above line is needed or else the .vcf file will be downloaded as a .htm file
     header('Content-disposition: attachment; filename="xxxxxxxxxx.vcf"');
     //header('Content-type: application/vcf'); remove this so android doesn't complain that it does not have a valid application
     //The above is the parth to where the file is located - if in same directory as the php, then just the file name

======= html ========================

<FONT COLOR="#CC0033"><a href="vCardDL.php">Download vCARD</A></FONT>

How to display raw html code in PRE or something like it but without escaping it

If you have jQuery enabled you can use an escapeXml function and not have to worry about escaping arrows or special characters.

    <!-- all your code --> 

favicon not working in IE

If you tried everything above and it still doesn’t work in IE, check your IIS settings if you are using a Windows Server. Make sure that the HTTP Headers > “Enable content expiration” setting, IS NOT SET to “Expire immediately”

Google Maps: How to create a custom InfoWindow?

You can use code below to remove style default inforwindow. After you can use HTML code for inforwindow:

var inforwindow = "<div style="border-radius: 50%"><img src='URL'></div>"; // show inforwindow image circle
marker.addListener('click', function() {
    $('.gm-style-iw').next().css({'height': '0px'}); //remove arrow bottom inforwindow
    $('.gm-style-iw').prev().html(''); //remove style default inforwindows

"Eliminate render-blocking CSS in above-the-fold content"

I too have struggled with this new pagespeed metric.

Although I have found no practical way to get my score back up to %100 there are a few things I have found helpful.

Combining all css into one file helped a lot. All my sites are back up to %95 - %98.

The only other thing I could think of was to inline all the necessary css (which appears to be most of it - at least for my pages) on the first page to get the sweet high score. Although it may help your speed score this will probably make your page load slower though.

How to change font in ipython notebook

In addition to the suggestion by Konrad here, I'd like to suggest jupyter themes, which seems to have more options, such as line-height, font size, cell width etc.

Command line usage:

jt  [-h] [-l] [-t THEME] [-f MONOFONT] [-fs MONOSIZE] [-nf NBFONT]
[-m MARGINS] [-cursw CURSORWIDTH] [-cursc CURSORCOLOR] [-vim]
[-cellw CELLWIDTH] [-lineh LINEHEIGHT] [-altp] [-P] [-T] [-N]
[-r] [-dfonts]

Oracle Date TO_CHAR('Month DD, YYYY') has extra spaces in it

try this:-

select to_char(to_date('01/10/2017','dd/mm/yyyy'),'fmMonth fmDD,YYYY') from dual;

select to_char(sysdate,'fmMonth fmDD,YYYY') from dual;

Issue with Task Scheduler launching a task

My task was set to Run only when user is logged on and it was failing for me even while I was logged in and starting it manually. The user was set to me already. No password changes, etc.

I solved it by clicking "Change user" and selecting myself again.

I suspect it may have been caused by AD changing the user SID or something to that extent. Perhaps IT was doing some user management in AD, who knows.

Execute another jar in a Java program

Hope this helps:

public class JarExecutor {

private BufferedReader error;
private BufferedReader op;
private int exitVal;

public void executeJar(String jarFilePath, List<String> args) throws JarExecutorException {
    // Create run arguments for the

    final List<String> actualArgs = new ArrayList<String>();
    actualArgs.add(0, "java");
    actualArgs.add(1, "-jar");
    actualArgs.add(2, jarFilePath);
    try {
        final Runtime re = Runtime.getRuntime();
        //final Process command = re.exec(cmdString, args.toArray(new String[0]));
        final Process command = re.exec(actualArgs.toArray(new String[0]));
        this.error = new BufferedReader(new InputStreamReader(command.getErrorStream()));
        this.op = new BufferedReader(new InputStreamReader(command.getInputStream()));
        // Wait for the application to Finish
        this.exitVal = command.exitValue();
        if (this.exitVal != 0) {
            throw new IOException("Failed to execure jar, " + this.getExecutionLog());

    } catch (final IOException | InterruptedException e) {
        throw new JarExecutorException(e);

public String getExecutionLog() {
    String error = "";
    String line;
    try {
        while((line = this.error.readLine()) != null) {
            error = error + "\n" + line;
    } catch (final IOException e) {
    String output = "";
    try {
        while((line = this.op.readLine()) != null) {
            output = output + "\n" + line;
    } catch (final IOException e) {
    try {
    } catch (final IOException e) {
    return "exitVal: " + this.exitVal + ", error: " + error + ", output: " + output;

SQL Not Like Statement not working

If WPP.COMMENT contains NULL, the condition will not match.

This query:


will return nothing.

On a NULL column, both LIKE and NOT LIKE against any search string will return NULL.

Could you please post relevant values of a row which in your opinion should be returned but it isn't?

jQuery validation plugin: accept only alphabetical characters?

Just a small addition to Nick's answer (which works great !) :

If you want to allow spaces in between letters, for example , you may restrict to enter only letters in full name, but it should allow space as well - just list the space as below with a comma. And in the same way if you need to allow any other specific character:

jQuery.validator.addMethod("lettersonly", function(value, element) 
return this.optional(element) || /^[a-z," "]+$/i.test(value);
}, "Letters and spaces only please");       

How to merge two files line by line in Bash

You can use paste:

paste file1.txt file2.txt > fileresults.txt

How to use not contains() in xpath?

Should be xpath with not contains() method, //production[not(contains(category,'business'))]

Click outside menu to close in jquery

Use the ':visible' selector. Where .menuitem is the to-hide element(s) ...


Or if you already have the .menuitem element(s) in a var ...

var menitems = $('.menuitem');

How to loop through an array containing objects and access their properties

Looping through an array of objects is a pretty fundamental functionality. This is what works for me.

var person = [];_x000D_
person[0] = {_x000D_
  firstName: "John",_x000D_
  lastName: "Doe",_x000D_
  age: 60_x000D_
var i, item;_x000D_
for (i = 0; i < person.length; i++) {_x000D_
  for (item in person[i]) {_x000D_
    document.write(item + ": " + person[i][item] + "<br>");_x000D_

How do I make an HTTP request in Swift?

In Swift 4.1 and Xcode 9.4.1.

JSON POST approach example. To check internet connection add Reachability.h & .m files from

func yourFunctionName {
    //Check internet connection
    let networkReachability = Reachability.forInternetConnection()
    let networkStatus:Int = (networkReachability?.currentReachabilityStatus())!.rawValue
    if networkStatus == NotReachable.rawValue {
        let msg = SharedClass.sharedInstance.noNetMsg//Message
        //Call alert from shared class
        SharedClass.sharedInstance.alert(view: self, title: "", message: msg)
    } else {
        //Call spinner from shared class
        SharedClass.sharedInstance.activityIndicator(view: self.view)//Play spinner

        let parameters = "Your parameters here"
        var request = URLRequest(url: URL(string: url)!)

        request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
        request.httpMethod = "POST"

        print("URL : \(request)")

        request.httpBody = .utf8)

        let task = URLSession.shared.dataTask(with: request) { data, response, error in guard let data = data, error == nil else { // check for fundamental networking error
            //Stop spinner
            SharedClass.sharedInstance.stopActivityIndicator() //Stop spinner
            //Print error in alert
            SharedClass.sharedInstance.alert(view: self, title: "", message: "\(String(describing: error!.localizedDescription))")

            SharedClass.sharedInstance.stopActivityIndicator() //Stop spinner

            if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 { // check for http errors
                print("statusCode should be 200, but is \(httpStatus.statusCode)")
                print("response = \(String(describing: response))")

            do {
                let response = try JSONSerialization.jsonObject(with: data, options: []) as? [String: AnyObject]
                //Your code here                    
            } catch let error as NSError {




If you have interest to use this function in SharedClass

//My shared class
import UIKit
class SharedClass: NSObject {

static let sharedInstance = SharedClass()

func postRequestFunction(apiName: String , parameters: String, onCompletion: @escaping (_ success: Bool, _ error: Error?, _ result: [String: Any]?)->()) {

    var URL =  "your URL here/index.php/***?"

    URL = URL.replacingOccurrences(of: "***", with: apiName)

    var request = URLRequest(url: URL(string: URL)!)
    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
    request.httpMethod = "POST"
    print("shared URL : \(request)")
    request.httpBody = .utf8)

    var returnRes:[String:Any] = [:]
    let task = URLSession.shared.dataTask(with: request) { data, response, error in

        if let error = error {
            onCompletion(false, error, nil)
        } else {
            guard let data = data else {
                onCompletion(false, error, nil)

            if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode == 200 {
                do {
                   returnRes = try JSONSerialization.jsonObject(with: data, options: []) as! [String : Any]
                    onCompletion(true, nil, returnRes)

                } catch let error as NSError {
                   onCompletion(false, error, nil)
            } else {
                onCompletion(false, error, nil)

private override init() {


And finally call this function like this....

SharedClass.sharedInstance.postRequestFunction(apiName: "Your API name", parameters: parameters) { (success, error, result) in
    if success {
        //Your code here
    } else {
        print(error?.localizedDescription ?? "")

How to auto-remove trailing whitespace in Eclipse?

You can map a key in Eclipse to manually remove trailing whitespaces in the whole file, but only on request instead of automatically at save. (Preference/Keys and then map a set of keys to File/Remove Trailing Whitespace) This can be useful if you want to sanitize all new files, but keep legacy code untouched.

Another strategy is to activate visual display of whitespace, so at least you'll know when you're adding some trailing whitespace. As far as I know, there's no way to display only trailing whitespace though, but I'll be glad to be proved wrong.

Link to add to Google calendar

For the next person Googling this topic, I've written a small NPM package to make it simple to generate Google Calendar URLs. It includes TypeScript type definitions, for those who need that. Hope it helps!

How do I remove newlines from a text file?

You can edit the file in vim:

$ vim inputfile

How to close the current fragment by using Button like the back button?

You can try this logic because it is worked for me.

frag_profile profile_fragment = new frag_profile();

boolean flag = false;
public void profile_Frag(){
    if (flag == false) {
        FragmentManager manager = getFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        transaction.setCustomAnimations(R.anim.transition_anim0, R.anim.transition_anim1);
        transaction.replace(, profile_fragment, "FirstFragment");
        flag = true;


public void onBackPressed() {
    if (flag == true) {
        FragmentManager manager = getFragmentManager();
        FragmentTransaction transaction = manager.beginTransaction();
        flag = false;
    else super.onBackPressed();

Similarity String Comparison in Java

There are indeed a lot of string similarity measures out there:

  • Levenshtein edit distance;
  • Damerau-Levenshtein distance;
  • Jaro-Winkler similarity;
  • Longest Common Subsequence edit distance;
  • Q-Gram (Ukkonen);
  • n-Gram distance (Kondrak);
  • Jaccard index;
  • Sorensen-Dice coefficient;
  • Cosine similarity;
  • ...

You can find explanation and java implementation of these here:

How can I pad an int with leading zeros when using cout << operator?

With the following,

#include <iomanip>
#include <iostream>

int main()
    std::cout << std::setfill('0') << std::setw(5) << 25;

the output will be


setfill is set to the space character (' ') by default. setw sets the width of the field to be printed, and that's it.

If you are interested in knowing how the to format output streams in general, I wrote an answer for another question, hope it is useful: Formatting C++ Console Output.

Finding median of list in Python

You can try the quickselect algorithm if faster average-case running times are needed. Quickselect has average (and best) case performance O(n), although it can end up O(n²) on a bad day.

Here's an implementation with a randomly chosen pivot:

import random

def select_nth(n, items):
    pivot = random.choice(items)

    lesser = [item for item in items if item < pivot]
    if len(lesser) > n:
        return select_nth(n, lesser)
    n -= len(lesser)

    numequal = items.count(pivot)
    if numequal > n:
        return pivot
    n -= numequal

    greater = [item for item in items if item > pivot]
    return select_nth(n, greater)

You can trivially turn this into a method to find medians:

def median(items):
    if len(items) % 2:
        return select_nth(len(items)//2, items)

        left  = select_nth((len(items)-1) // 2, items)
        right = select_nth((len(items)+1) // 2, items)

        return (left + right) / 2

This is very unoptimised, but it's not likely that even an optimised version will outperform Tim Sort (CPython's built-in sort) because that's really fast. I've tried before and I lost.

How to reload page the page with pagination in Angular 2?

This should technically be achievable using window.location.reload():


<button (click)="refresh()">Refresh</button>


refresh(): void {


Here is a basic StackBlitz example showing the refresh in action. Notice the URL on "/hello" path is retained when window.location.reload() is executed.

Event listener for when element becomes visible?

Javascript events deal with User Interaction, if your code is organised enough you should be able to call the initialising function in the same place where the visibility changes (i.e. you shouldn't change on many places, instead, call a function/method that does this and anything else you might want).

How can I use a local image as the base image with a dockerfile?

Verified: it works well in Docker 1.7.0.

Don't specify --pull=true when running the docker build command

From this thread on reference locally-built image using FROM at dockerfile:

If you want use the local image as the base image, pass without the option --pull=true
--pull=true will always attempt to pull a newer version of the image.

How to use Javascript to read local text file and read line by line?

Without jQuery:

document.getElementById('file').onchange = function(){

  var file = this.files[0];

  var reader = new FileReader();
  reader.onload = function(progressEvent){
    // Entire file

    // By lines
    var lines = this.result.split('\n');
    for(var line = 0; line < lines.length; line++){


<input type="file" name="file" id="file">

Remember to put your javascript code after the file field is rendered.

Using 24 hour time in bootstrap timepicker

  showInputs: false,
  showMeridian: false //24hr mode 

Blue and Purple Default links, how to remove?

<a href="https://www." style="color: inherit;"target="_blank">

For CSS inline style, this worked best for me.

How to store an array into mysql?

Consider normalizing the table structure into a comments, and a separate votes table.

Table "comments":


Table "votes":

vote (downvote/upvote)

this would allow an unlimited number of votes without having to deal with the limits of a database field.

Also, you may have future needs for operations like "show all votes a user has cast", removing specific votes or limiting the maximum number of votes per day. These operations are dead easy and fast to implement with a normalized structure, and horribly slow and complex in a serialized array.

Enabling CORS in Cloud Functions for Firebase

One additional piece of info, just for the sake of those googling this after some time: If you are using firebase hosting, you can also set up rewrites, so that for example a url like (firebase_hosting_host)/api/myfunction redirects to the (firebase_cloudfunctions_host)/doStuff function. That way, since the redirection is transparent and server-side, you don't have to deal with cors.

You can set that up with a rewrites section in firebase.json:

"rewrites": [
        { "source": "/api/myFunction", "function": "doStuff" }

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)

React JSX: selecting "selected" on selected <select> option

With React 16.8. We can do this with hooks like the following example

Codesandbox link

import React, { useState } from "react";
import "./styles.css";

export default function App() {
  const options = [
    "Monty Python and the Holy Grail",
    "Monty Python's Life of Brian",
    "Monty Python's The Meaning of Life"
  const filmsByTati = [
      id: 1,
      title: "Jour de fête",
      releasedYear: 1949
      id: 2,
      title: "Play time",
      releasedYear: 1967
      id: 3,
      releasedYear: 1958,
      title: "Mon Oncle"
  const [selectedOption, setSelectedOption] = useState(options[0]);
  const [selectedTatiFilm, setSelectedTatiFilm] = useState(filmsByTati[0]);
  return (
    <div className="App">
      <h1>Select Example</h1>
        onChange={(e) => setSelectedOption(}
        { => (
          <option key={option} value={option}>
      <span>Selected option: {selectedOption}</span>

        onChange={(e) =>
            filmsByTati.find(film => ( ==
        { => (
          <option key={} value={}>
      <span>Selected option: {selectedTatiFilm.title}</span>

How to remove \xa0 from string in Python?

I end up here while googling for the problem with not printable character. I use MySQL UTF-8 general_ci and deal with polish language. For problematic strings I have to procced as follows:

text=text.replace('\xc2\xa0', ' ')

It is just fast workaround and you probablly should try something with right encoding setup.

How to format LocalDate to string?

There is a built-in way to format LocalDate in Joda library

import org.joda.time.LocalDate;

LocalDate localDate =;
String dateFormat = "MM/dd/yyyy";

In case you don't have it already - add this to the build.gradle:

implementation 'joda-time:joda-time:2.9.5'

Happy coding! :)

How can I check if a MySQL table exists with PHP?

The cleanest way to achieve this in PHP is to simply use DESCRIBE statement.

if ( mysql_query( "DESCRIBE `my_table`" ) ) {
    // my_table exists

I'm not sure why others are posting complicated queries for a such a straight forward problem.


Using PDO

// assuming you have already setup $pdo
$sh = $pdo->prepare( "DESCRIBE `my_table`");
if ( $sh->execute() ) {
    // my_table exists
} else {
    // my_table does not exist    

Understanding the Linux oom-killer's logs

Memory management in Linux is a bit tricky to understand, and I can't say I fully understand it yet, but I'll try to share a little bit of my experience and knowledge.

Short answer to your question: Yes there are other stuff included than whats in the list.

What's being shown in your list is applications run in userspace. The kernel uses memory for itself and modules, on top of that it also has a lower limit of free memory that you can't go under. When you've reached that level it will try to free up resources, and when it can't do that anymore, you end up with an OOM problem.

From the last line of your list you can read that the kernel reports a total-vm usage of: 1498536kB (1,5GB), where the total-vm includes both your physical RAM and swap space. You stated you don't have any swap but the kernel seems to think otherwise since your swap space is reported to be full (Total swap = 524284kB, Free swap = 0kB) and it reports a total vmem size of 1,5GB.

Another thing that can complicate things further is memory fragmentation. You can hit the OOM killer when the kernel tries to allocate lets say 4096kB of continous memory, but there are no free ones availible.

Now that alone probably won't help you solve the actual problem. I don't know if it's normal for your program to require that amount of memory, but I would recommend to try a static code analyzer like cppcheck to check for memory leaks or file descriptor leaks. You could also try to run it through Valgrind to get a bit more information out about memory usage.

How do I sort a vector of pairs based on the second element of the pair?

You can use boost like this:

std::sort(a.begin(), a.end(), 
          boost::bind(&std::pair<int, int>::second, _1) <
          boost::bind(&std::pair<int, int>::second, _2));

I don't know a standard way to do this equally short and concise, but you can grab boost::bind it's all consisting of headers.

invalid byte sequence for encoding "UTF8"

I ran into this problem under Windows while working exclusively with psql (no graphical tools). To fix this problem, permanently change the default encoding of psql (client) to match the default encoding of the PostgreSQL server. Run the following command in CMD or Powershell:


Close and reopen you command prompt/Powershell for the change to take effect.

Change the encoding of the backup file from Unicode to UTF8 by opening it with Notepad and going to File -> Save As. Change the Encoding dropdown from Unicode to UTF8. (Also change the Save as type from Text Documents (.txt) to All Files in order to avoid adding the .txt extension to your backup file's name). You should now be able to restore your backup.

How to find all the tables in MySQL with specific column names in them?

More simply done in one line of SQL:

SELECT * FROM information_schema.columns WHERE column_name = 'column_name';

Combine a list of data frames into one data frame by row

The only thing that the solutions with data.table are missing is the identifier column to know from which dataframe in the list the data is coming from.

Something like this:

df_id <- data.table::rbindlist(listOfDataFrames, idcol = TRUE)

The idcol parameter adds a column (.id) identifying the origin of the dataframe contained in the list. The result would look to something like this:

.id a         b           c
1   u   -0.05315128 -1.31975849 
1   b   -1.00404849 1.15257952  
1   y   1.17478229  -0.91043925 
1   q   -1.65488899 0.05846295  
1   c   -1.43730524 0.95245909  
1   b   0.56434313  0.93813197  

Any free WPF themes?

I bought a theme from The themes ship with source code so you can tweak them. They also offer a free theme (source code included).

Create a file if it doesn't exist

Well, first of all, in Python there is no ! operator, that'd be not. But open would not fail silently either - it would throw an exception. And the blocks need to be indented properly - Python uses whitespace to indicate block containment.

Thus we get:

fn = input('Enter file name: ')
    file = open(fn, 'r')
except IOError:
    file = open(fn, 'w')

Basic calculator in Java

Remove the semi-colons from your if statements, otherwise the code that follows will be free standing and will always execute:

if (operation == "+");

Also use .equals for Strings, == compares Object references:

 if (operation.equals("+")) {

Android device chooser - My device seems offline

Tried a lot of the solutions without success and then I

  1. Clicked "Revoke USB debugging authorizations
  2. Unchecked "USB debugging"
  3. Checked "USB debugging"

How to Specify "Vary: Accept-Encoding" header in .htaccess

Many hours spent to clarify what was that. Please, read this post to get the advanced .HTACCESS codes and learn what they do.

You can use:

Header append Vary "Accept-Encoding"
Header set Vary "Accept-Encoding"

How do I drop a MongoDB database from the command line?

You don't need heredocs or eval, mongo itself can act as an interpreter.

#!/usr/bin/env mongo
var db = new Mongo().getDB("someDatabase");

Make the file executable and run it.

How to override trait function and call it from the overridden function?

Your last one was almost there:

trait A {
    function calc($v) {
        return $v+1;

class MyClass {
    use A {
        calc as protected traitcalc;

    function calc($v) {
        return $this->traitcalc($v);

The trait is not a class. You can't access its members directly. It's basically just automated copy and paste...

How do I get the height and width of the Android Navigation Bar programmatically?

I resolved this issue for all devices(including Nexus 5, Samsung Galaxy Nexus 6 edge+, Samsung S10, Samsung Note II etc.). I think this will help you to handle device dependant issues.

Here I am adding two types of codes,

Java Code(for Native Android):

import android.content.Context;
import android.content.res.Resources;
import android.os.Build;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.ViewConfiguration;
import android.view.WindowManager;

public class DeviceSpec {

    private int resourceID = -1;
    private Display display = null;
    private DisplayMetrics displayMetrics = null;
    private DisplayMetrics realDisplayMetrics = null;
    private Resources resources = null;
    private WindowManager windowManager = null;

    public double GetNavigationBarHeight(Context context) {
        try {
            windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
            display = windowManager.getDefaultDisplay();
            displayMetrics = new DisplayMetrics();
                realDisplayMetrics = new DisplayMetrics();
                if(displayMetrics.heightPixels != realDisplayMetrics.heightPixels) {
                    resources = context.getResources();
                    return GetNavigationBarSize(context);
            else {
                resources = context.getResources();
                resourceID = resources.getIdentifier("config_showNavigationBar", "bool", "android");
                if (resourceID > 0 && resources.getBoolean(resourceID))
                    return GetNavigationBarSize(context);
        catch (Exception e){
        return 0;

    private double GetNavigationBarSize(Context context) {
        resourceID = resources.getIdentifier("navigation_bar_height", "dimen", "android");
        if (resourceID > 0 && ViewConfiguration.get(context).hasPermanentMenuKey())
           return (resources.getDimensionPixelSize(resourceID) / displayMetrics.density);
        return 0;

And C# code(for Xamarin Forms/Android)

int resourceId = -1;
        IWindowManager windowManager = null;
        Display defaultDisplay = null;
        DisplayMetrics displayMatrics = null;
        DisplayMetrics realMatrics = null;
        Resources resources = null;

        public double NavigationBarHeight
                    windowManager = Forms.Context.GetSystemService(Context.WindowService).JavaCast<IWindowManager>();
                    defaultDisplay = windowManager.DefaultDisplay;
                    displayMatrics = new DisplayMetrics();
                    if (Build.VERSION.SdkInt >= BuildVersionCodes.JellyBeanMr2)
                        realMatrics = new DisplayMetrics();
                        if (displayMatrics.HeightPixels != realMatrics.HeightPixels)
                            resources = Forms.Context.Resources;
                            return GetHeightOfNivigationBar();
                    else {
                        resources = Forms.Context.Resources;
                        resourceId = resources.GetIdentifier("config_showNavigationBar", "bool", "android");
                        if (resourceId > 0 && resources.GetBoolean(resourceId))
                            return GetHeightOfNivigationBar();
                catch (Exception e) { }
                return 0;

        private double GetHeightOfNivigationBar()
            resourceId = resources.GetIdentifier("navigation_bar_height", "dimen", "android");
            if (!ViewConfiguration.Get(Forms.Context).HasPermanentMenuKey && resourceId > 0)
                return resources.GetDimensionPixelSize(resourceId) / displayMatrics.Density;
            return 0;

Does Java have a path joining method?

One way is to get system properties that give you the path separator for the operating system, this tutorial explains how. You can then use a standard string join using the file.separator.

Already defined in .obj - no double inclusions

This is one of the method to overcome this issue.

  • Just put the prototype in the header files and include the header files in the .cpp files as shown below.


#include <boost/asio.hpp>

class SocketClient // Or whatever the name is... {

// ...

    bool read(int, char*); // Or whatever the name is...

//  ... };



bool SocketClient::read(int, char*)
    // Implementation  goes here...


#include <iostream>
#include <string>
#include <sstream>
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
#include "client.h"
//              ^^ Notice this!


int main()

Select current date by default in ASP.Net Calendar control

I too had the same problem in VWD 2010 and, by chance, I had two controls. One was available in code behind and one wasn't accessible. I thought that the order of statements in the controls was causing the issue. I put 'runat' before 'SelectedDate' and that seemed to fix it. When I put 'runat' after 'SelectedDate' it still worked! Unfortunately, I now don't know why it didn't work and haven't got the original that didn't work.

These now all work:-

<asp:Calendar ID="calDateFrom" SelectedDate="08/02/2011" SelectionMode="Day" runat="server"></asp:Calendar>
<asp:Calendar runat="server" SelectionMode="Day" SelectedDate="08/15/2011 12:00:00 AM" ID="Calendar1" VisibleDate="08/03/2011 12:00:00 AM"></asp:Calendar>
<asp:Calendar SelectionMode="Day" SelectedDate="08/31/2011 12:00:00 AM" runat="server" ID="calDateTo"></asp:Calendar>

How to run jenkins as a different user

If you really want to run Jenkins as you, I suggest you check out my An alternative, easy way to run Jenkins on Mac.


Download it from

Updates were rejected because the tip of your current branch is behind its remote counterpart

The command I used with Azure DevOps when I encountered the message "updates were rejected because the tip of your current branch is behind" was/is this command:

git pull origin master

(or can start with a new folder and do a Clone) ..

This answer doesn't address the question posed, specifically, Keif has answered this above, but it does answer the question's title/heading text and this will be a common question for Azure DevOps users.

I noted comment: "You'd always want to make sure that you do a pull before pushing" in answer from Keif above !

I have also used Git Gui tool in addition to Git command line tool.

(I wasn't sure how to do the equivalent of the command line command "git pull origin master" within Git Gui so I'm back to command line to do this).

A diagram that shows various git commands for various actions that you might want to undertake is this one:

enter image description here

How do I concatenate const/literal strings in C?

It is undefined behaviour to attempt to modify string literals, which is what something like:

strcat ("Hello, ", name);

will attempt to do. It will try to tack on the name string to the end of the string literal "Hello, ", which is not well defined.

Try something this. It achieves what you appear to be trying to do:

char message[1000];
strcpy (message, "TEXT ");
strcat (message, var);

This creates a buffer area that is allowed to be modified and then copies both the string literal and other text to it. Just be careful with buffer overflows. If you control the input data (or check it before-hand), it's fine to use fixed length buffers like I have.

Otherwise, you should use mitigation strategies such as allocating enough memory from the heap to ensure you can handle it. In other words, something like:

const static char TEXT[] = "TEXT ";

// Make *sure* you have enough space.

char *message = malloc (sizeof(TEXT) + strlen(var) + 1);
if (message == NULL)
strcpy (message, TEXT);
strcat (message, var);

// Need to free message at some point after you're done with it.

SqlBulkCopy - The given value of type String from the data source cannot be converted to type money of the specified target column

Check The data you are writing to Server. May be data has delimiter which is not used.



your delimiter is '|' but data has a delimiter ';'. So for this you are getting the error.

FFT in a single C-file

This file works properly as it is: just copy and paste in your computer. Surfing on the web I have found this easy implementation on wikipedia page here. The page is in italian, so I re-wrote the code with some translations. Here there are almost the same informations but in english. ENJOY!

#include <iostream>
#include <complex>
#define MAX 200

using namespace std;

#define M_PI 3.1415926535897932384

int log2(int N)    /*function to calculate the log2(.) of int numbers*/
  int k = N, i = 0;
  while(k) {
    k >>= 1;
  return i - 1;

int check(int n)    //checking if the number of element is a power of 2
  return n > 0 && (n & (n - 1)) == 0;

int reverse(int N, int n)    //calculating revers number
  int j, p = 0;
  for(j = 1; j <= log2(N); j++) {
    if(n & (1 << (log2(N) - j)))
      p |= 1 << (j - 1);
  return p;

void ordina(complex<double>* f1, int N) //using the reverse order in the array
  complex<double> f2[MAX];
  for(int i = 0; i < N; i++)
    f2[i] = f1[reverse(N, i)];
  for(int j = 0; j < N; j++)
    f1[j] = f2[j];

void transform(complex<double>* f, int N) //
  ordina(f, N);    //first: reverse order
  complex<double> *W;
  W = (complex<double> *)malloc(N / 2 * sizeof(complex<double>));
  W[1] = polar(1., -2. * M_PI / N);
  W[0] = 1;
  for(int i = 2; i < N / 2; i++)
    W[i] = pow(W[1], i);
  int n = 1;
  int a = N / 2;
  for(int j = 0; j < log2(N); j++) {
    for(int i = 0; i < N; i++) {
      if(!(i & n)) {
        complex<double> temp = f[i];
        complex<double> Temp = W[(i * a) % (n * a)] * f[i + n];
        f[i] = temp + Temp;
        f[i + n] = temp - Temp;
    n *= 2;
    a = a / 2;

void FFT(complex<double>* f, int N, double d)
  transform(f, N);
  for(int i = 0; i < N; i++)
    f[i] *= d; //multiplying by step

int main()
  int n;
  do {
    cout << "specify array dimension (MUST be power of 2)" << endl;
    cin >> n;
  } while(!check(n));
  double d;
  cout << "specify sampling step" << endl; //just write 1 in order to have the same results of matlab fft(.)
  cin >> d;
  complex<double> vec[MAX];
  cout << "specify the array" << endl;
  for(int i = 0; i < n; i++) {
    cout << "specify element number: " << i << endl;
    cin >> vec[i];
  FFT(vec, n, d);
  cout << "...printing the FFT of the array specified" << endl;
  for(int j = 0; j < n; j++)
    cout << vec[j] << endl;
  return 0;

C++ string to double conversion

The problem is that C++ is a statically-typed language, meaning that if something is declared as a string, it's a string, and if something is declared as a double, it's a double. Unlike other languages like JavaScript or PHP, there is no way to automatically convert from a string to a numeric value because the conversion might not be well-defined. For example, if you try converting the string "Hi there!" to a double, there's no meaningful conversion. Sure, you could just set the double to 0.0 or NaN, but this would almost certainly be masking the fact that there's a problem in the code.

To fix this, don't buffer the file contents into a string. Instead, just read directly into the double:

double lol;
openfile >> lol;

This reads the value directly as a real number, and if an error occurs will cause the stream's .fail() method to return true. For example:

double lol;
openfile >> lol;

if ( {
    cout << "Couldn't read a double from the file." << endl;

Adding minutes to date time in PHP

I don't know why the approach set as solution didn't work for me. So I'm posting here what worked for me in hope it can help anybody:

$startTime = date("Y-m-d H:i:s");

//display the starting time
echo '> '.$startTime . "<br>";

//adding 2 minutes
$convertedTime = date('Y-m-d H:i:s', strtotime('+2 minutes', strtotime($startTime)));

//display the converted time
echo '> '.$convertedTime;

Iterator over HashMap in Java

You should really use generics and the enhanced for loop for this:

Map<Integer, String> hm = new HashMap<>();
hm.put(0, "zero");
hm.put(1, "one");

for (Integer key : hm.keySet()) {

Or the entrySet() version:

Map<Integer, String> hm = new HashMap<>();
hm.put(0, "zero");
hm.put(1, "one");

for (Map.Entry<Integer, String> e : hm.entrySet()) {

Is it possible to wait until all javascript files are loaded before executing javascript code?

You can use .getScript() and run your code after it loads:

 $.getScript("my_lovely_script.js", function(){

    alert("Script loaded and executed.");
    // here you can use anything you defined in the loaded script


You can see a better explanation here: How do I include a JavaScript file in another JavaScript file?

Best way to import Observable from rxjs

Rxjs v 6.*

It got simplified with newer version of rxjs .

1) Operators

import {map} from 'rxjs/operators';

2) Others

import {Observable,of, from } from 'rxjs';

Instead of chaining we need to pipe . For example

Old syntax :

New Syntax:

source.pipe(map(), switchMap()).subscribe()

Note: Some operators have a name change due to name collisions with JavaScript reserved words! These include:

do -> tap,

catch -> catchError

switch -> switchAll

finally -> finalize

Rxjs v 5.*

I am writing this answer partly to help myself as I keep checking docs everytime I need to import an operator . Let me know if something can be done better way.

1) import { Rx } from 'rxjs/Rx';

This imports the entire library. Then you don't need to worry about loading each operator . But you need to append Rx. I hope tree-shaking will optimize and pick only needed funcionts( need to verify ) As mentioned in comments , tree-shaking can not help. So this is not optimized way.

public cache = new Rx.BehaviorSubject('');

Or you can import individual operators .

This will Optimize your app to use only those files :

2) import { _______ } from 'rxjs/_________';

This syntax usually used for main Object like Rx itself or Observable etc.,

Keywords which can be imported with this syntax

 Observable, Observer, BehaviorSubject, Subject, ReplaySubject

3) import 'rxjs/add/observable/__________';

Update for Angular 5

With Angular 5, which uses rxjs 5.5.2+

import { empty } from 'rxjs/observable/empty';
import { concat} from 'rxjs/observable/concat';

These are usually accompanied with Observable directly. For example


Other such keywords which can be imported using this syntax:

concat, defer, empty, forkJoin, from, fromPromise, if, interval, merge, of, 
range, throw, timer, using, zip

4) import 'rxjs/add/operator/_________';

Update for Angular 5

With Angular 5, which uses rxjs 5.5.2+

import { filter } from 'rxjs/operators/filter';
import { map } from 'rxjs/operators/map';

These usually come in the stream after the Observable is created. Like flatMap in this code snippet:

          .flatMap(arr => Observable.from(arr));

Other such keywords using this syntax:

audit, buffer, catch, combineAll, combineLatest, concat, count, debounce, delay, 
distinct, do, every, expand, filter, finally, find , first, groupBy,
ignoreElements, isEmpty, last, let, map, max, merge, mergeMap, min, pluck, 
publish, race, reduce, repeat, scan, skip, startWith, switch, switchMap, take, 
takeUntil, throttle, timeout, toArray, toPromise, withLatestFrom, zip

FlatMap: flatMap is alias to mergeMap so we need to import mergeMap to use flatMap.

Note for /add imports :

We only need to import once in whole project. So its advised to do it at a single place. If they are included in multiple files, and one of them is deleted, the build will fail for wrong reasons.

How to POST JSON request using Apache HttpClient?

As mentioned in the excellent answer by janoside, you need to construct the JSON string and set it as a StringEntity.

To construct the JSON string, you can use any library or method you are comfortable with. Jackson library is one easy example:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;

ObjectMapper mapper = new ObjectMapper();
ObjectNode node = mapper.createObjectNode();
node.put("name", "value"); // repeat as needed
String JSON_STRING = node.toString();
postMethod.setEntity(new StringEntity(JSON_STRING, ContentType.APPLICATION_JSON));

ORA-01017 Invalid Username/Password when connecting to 11g database from 9i client

You may connect to Oracle database using sqlplus:

sqlplus "/as sysdba"

Then create new users and assign privileges.

grant all privileges to dac;

How can I check Drupal log files?

We can use drush command also to check logs drush watchdog-show it will show recent 10 messages.

or if we want to continue showing logs with more information we can user

drush watchdog-show --tail --full.

Import and insert sql.gz file into database with putty

For an oneliner, on linux or cygwin, you need to do public key authentication on the host, otherwise ssh will be asking for password.

gunzip -c numbers.sql.gz | ssh user@host mysql --user=user_name --password=your_password db_name

Or do port forwarding and connect to the remote mysql using a "local" connection:

ssh -L some_port:host:local_mysql_port user@host

then do the mysql connection on your local machine to localhost:some_port.

The port forwarding will work from putty too, with the similar -L option or you can configure it from the settings panel, somewhere down on the tree.

jQuery/Javascript function to clear all the fields of a form

    <form id="form" method="post" action="action.php">
      <input type="text" class="removeLater" name="name" /> Username<br/>
      <input type="text" class="removeLater" name="pass" /> Password<br/>
      <input type="text" class="removeLater" name="pass2" /> Password again<br/>
         //do anything you want
         //& remove values


element with the max height from a set of elements

If you were interested in sorting entirely in standard JavaScript, or without using forEach():

var panels = document.querySelectorAll("div.panel");

// You'll need to slice the node_list before using .map()
var heights = (panel) {
    // return an array to hold the item and its value
    return [panel, panel.offsetHeight];

// Returns a sorted array
var sortedHeights = heights.sort(function(a, b) { return a[1] > b[1]});

Should I Dispose() DataSet and DataTable?

No need to Dispose() because DataSet inherit MarshalByValueComponent class and MarshalByValueComponent implement IDisposable Interface

Utility of HTTP header "Content-Type: application/force-download" for mobile?

To download a file please use the following code ... Store the File name with location in $file variable. It supports all mime type

$file = "location of file to download"
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.basename($file));
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header('Content-Length: ' . filesize($file));

To know about Mime types please refer to this link:

Can an AJAX response set a cookie?

For the record, be advised that all of the above is (still) true only if the AJAX call is made on the same domain. If you're looking into setting cookies on another domain using AJAX, you're opening a totally different can of worms. Reading cross-domain cookies does work, however (or at least the server serves them; whether your client's UA allows your code to access them is, again, a different topic; as of 2014 they do).

Very Long If Statement in Python

According to PEP8, long lines should be placed in parentheses. When using parentheses, the lines can be broken up without using backslashes. You should also try to put the line break after boolean operators.

Further to this, if you're using a code style check such as pycodestyle, the next logical line needs to have different indentation to your code block.

For example:

if (abcdefghijklmnopqrstuvwxyz > some_other_long_identifier and
        here_is_another_long_identifier != and_finally_another_long_name):
    # ... your code here ...

How do I tell what type of value is in a Perl variable?


Perl provides the ref() function so that you can check the reference type before dereferencing a reference...

By using the ref() function you can protect program code that dereferences variables from producing errors when the wrong type of reference is used...

The type cannot be resolved. It is indirectly referenced from required .class files

Using the latest 7.x Tomcat (currently 7.0.69) solved the problem for me.

We did also try a workaround in a old eclipse bug, maybe that did it's part to solve the problem, too?


  • Window->Preferences->Java->Installed JREs
  • Uncheck selected JRE
  • Click OK (this step may be optional?)
  • Check JRE again

PHP - Modify current object in foreach loop

Surely using array_map and if using a container implementing ArrayAccess to derive objects is just a smarter, semantic way to go about this?

Array map semantics are similar across most languages and implementations that I've seen. It's designed to return a modified array based upon input array element (high level ignoring language compile/runtime type preference); a loop is meant to perform more logic.

For retrieving objects by ID / PK, depending upon if you are using SQL or not (it seems suggested), I'd use a filter to ensure I get an array of valid PK's, then implode with comma and place into an SQL IN() clause to return the result-set. It makes one call instead of several via SQL, optimising a bit of the call->wait cycle. Most importantly my code would read well to someone from any language with a degree of competence and we don't run into mutability problems.


$arr = [0,1,2,3,4];
$arr2 = array_map(function($value) { return is_int($value) ? $value*2 : $value; }, $arr);



$arr = [0,1,2,3,4];
foreach($arr as $i => $item) {
    $arr[$i] = is_int($item) ? $item * 2 : $item;

If you know what you are doing will never have mutability problems (bearing in mind if you intend upon overwriting $arr you could always $arr = array_map and be explicit.

Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.9.4 or earlier

You can only use - on the numeric entries, so you can use decreasing and negate the ones you want in increasing order:

      x y v
 [1,] c 1 7
 [2,] c 3 8
 [3,] c 6 9
 [4,] b 1 1
 [5,] b 3 2
 [6,] b 6 3
 [7,] a 1 4
 [8,] a 3 5
 [9,] a 6 6

How to detect window.print() finish

Implementing window.onbeforeprint and window.onafterprint

The window.close() call after the window.print() is not working in Chrome v 78.0.3904.70

To approach this I'm using Adam's answer with a simple modification:

     function print() {
    (function () {
       let afterPrintCounter = !! ? 0 : 1;
       let beforePrintCounter = !! ? 0 : 1;
       var beforePrint = function () {
          if (beforePrintCounter === 2) {
             console.log('Functionality to run before printing.');
       var afterPrint = function () {
          if (afterPrintCounter === 2) {
             console.log('Functionality to run after printing.');
       if (window.matchMedia) {
          var mediaQueryList = window.matchMedia('print');
          mediaQueryList.addListener(function (mql) {
             if (mql.matches) {
             } else {
       window.onbeforeprint = beforePrint;
       window.onafterprint = afterPrint;
    //window.print(); //To print the page when it is loaded

I'm calling it in here:

<body onload="print();">

This works for me. Note that I use a counter for both functions, so that I can handle this event in different browsers (fires twice in Chrome, and one time in Mozilla). For detecting the browser you can refer to this answer

How can I use external JARs in an Android project?

For Eclipse

A good way to add external JARs to your Android project or any Java project is:

  1. Create a folder called libs in your project's root folder
  2. Copy your JAR files to the libs folder
  3. Now right click on the Jar file and then select Build Path > Add to Build Path, which will create a folder called 'Referenced Libraries' within your project

    By doing this, you will not lose your libraries that are being referenced on your hard drive whenever you transfer your project to another computer.

For Android Studio

  1. If you are in Android View in project explorer, change it to Project view as below

Missing Image

  1. Right click the desired module where you would like to add the external library, then select New > Directroy and name it as 'libs'
  2. Now copy the blah_blah.jar into the 'libs' folder
  3. Right click the blah_blah.jar, Then select 'Add as Library..'. This will automatically add and entry in build.gradle as compile files('libs/blah_blah.jar') and sync the gradle. And you are done

Please Note : If you are using 3rd party libraries then it is better to use transitive dependencies where Gradle script automatically downloads the JAR and the dependency JAR when gradle script run.

Ex : compile ''

Read more about Gradle Dependency Mangement

How to create a signed APK file using Cordova command line interface?

First Check your version code and version name if you are updating your app. And make sure you have a previous keystore.

If you are updating app then follow step 1,3,4.

Step 1:

Goto your cordova project for generate our release build:

D:\projects\Phonegap\Example> cordova build --release android

Then, we can find our unsigned APK file in platforms/android/ant-build. In our example, the file was

if u used ant-build



if u used gradle-build


Step 2:

Key Generation:


keytool -genkey -v -keystore <keystoreName>.keystore -alias <Keystore AliasName> -keyalg <Key algorithm> -keysize <Key size> -validity <Key Validity in Days>

if keytool command not recognize do this step

Check that the directory the keytool executable is in is on your path. (For example, on my Windows 7 machine, it's in C:\Program Files (x86)\Java\jre6\bin.)


keytool -genkey -v -keystore NAME-mobileapps.keystore -alias NAMEmobileapps -keyalg RSA -keysize 2048 -validity 10000

keystore password? : xxxxxxx
What is your first and last name? :  xxxxxx
What is the name of your organizational unit? :  xxxxxxxx
What is the name of your organization? :  xxxxxxxxx
What is the name of your City or Locality? :  xxxxxxx
What is the name of your State or Province? :  xxxxx
What is the two-letter country code for this unit? :  xxx

Then the Key store has been generated with name as NAME-mobileapps.keystore

Step 3:

Place the generated keystore in D:\projects\Phonegap\Example\platforms\android\ant-build

To sign the unsigned APK, run the jarsigner tool which is also included in the JDK:


jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore <keystorename <Unsigned APK file> <Keystore Alias name>

If it doesn't reconize do these steps

(1) Right click on "This PC" > right-click Properties > Advanced system settings > Environment Variables > select PATH then EDIT.

(2) Add your jdk bin folder path to environment variables, it should look like this:

"C:\Program Files\Java\jdk1.8.0_40\bin".


D:\projects\Phonegap\Example\platforms\android\ant-build> jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore NAME-mobileapps.keystore Example-release-unsigned.apk xxxxxmobileapps

Enter KeyPhrase as 'xxxxxxxx'

This signs the apk in place.

Step 4:

Finally, we need to run the zip align tool to optimize the APK:

if zipalign not recognize then

(1) goto your android sdk path and find zipalign it is usually in android-sdk\build-tools\23.0.3

(2) Copy zipalign file paste into your generate release apk folder usually in below path


D:\projects\Phonegap\Example\platforms\android\ant-build> zipalign -v 4 Example-release-unsigned.apk Example.apk 


D:\projects\Phonegap\Example\platforms\android\ant-build> C:\Phonegap\adt-bundle-windows-x86_64-20140624\sdk\build-tools\android-4.4W\zipalign -v 4 Example-release-unsigned.apk Example.apk

Now we have our final release binary called example.apk and we can release this on the Google Play Store.

C++ Remove new line from multiline string

You should use the erase-remove idiom, looking for '\n'. This will work for any standard sequence container; not just string.

Set inputType for an EditText Programmatically?

Try adding this to the EditText/TextView tag in your layout


Edit: I just re-read your post, perhaps you need to do this after construction. I don't see why your snippet wouldn't work. :connection timed out: connect?

Exception :

This means your request didn't getting response from server in stipulated time. And their are some reasons for this exception:

  • Too many requests overloading the server
  • Request packet loss because of wrong network configuration or line overload
  • Sometimes firewall consume request packet before sever getting
  • Also depends on thread connection pool configuration and current status of connection pool
  • Response packet lost during transition

Why does LayoutInflater ignore the layout_width and layout_height layout parameters I've specified?

I've investigated this issue, referring to the LayoutInflater docs and setting up a small sample demonstration project. The following tutorials shows how to dynamically populate a layout using LayoutInflater.

Before we get started see what LayoutInflater.inflate() parameters look like:

  • resource: ID for an XML layout resource to load (e.g., R.layout.main_page)
  • root: Optional view to be the parent of the generated hierarchy (if attachToRoot is true), or else simply an object that provides a set of LayoutParams values for root of the returned hierarchy (if attachToRoot is false.)
  • attachToRoot: Whether the inflated hierarchy should be attached to the root parameter? If false, root is only used to create the correct subclass of LayoutParams for the root view in the XML.

  • Returns: The root View of the inflated hierarchy. If root was supplied and attachToRoot is true, this is root; otherwise it is the root of the inflated XML file.

Now for the sample layout and code.

Main layout (main.xml):

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

Added into this container is a separate TextView, visible as small red square if layout parameters are successfully applied from XML (red.xml):

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

Now LayoutInflater is used with several variations of call parameters

public class InflaterTest extends Activity {

    private View view;

    public void onCreate(Bundle savedInstanceState) {

      ViewGroup parent = (ViewGroup) findViewById(;

      // result: layout_height=wrap_content layout_width=match_parent
      view = LayoutInflater.from(this).inflate(, null);

      // result: layout_height=100 layout_width=100
      view = LayoutInflater.from(this).inflate(, null);
      parent.addView(view, 100, 100);

      // result: layout_height=25dp layout_width=25dp
      // view=textView due to attachRoot=false
      view = LayoutInflater.from(this).inflate(, parent, false);

      // result: layout_height=25dp layout_width=25dp 
      // parent.addView not necessary as this is already done by attachRoot=true
      // view=root due to parent supplied as hierarchy root and attachRoot=true
      view = LayoutInflater.from(this).inflate(, parent, true);

The actual results of the parameter variations are documented in the code.

SYNOPSIS: Calling LayoutInflater without specifying root leads to inflate call ignoring the layout parameters from the XML. Calling inflate with root not equal null and attachRoot=true does load the layout parameters, but returns the root object again, which prevents further layout changes to the loaded object (unless you can find it using findViewById()). The calling convention you most likely would like to use is therefore this one:

loadedView = LayoutInflater.from(context)
                .inflate(R.layout.layout_to_load, parent, false);

To help with layout issues, the Layout Inspector is highly recommended.

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

To calculate log base 2 of n, following expression can be used:

double res = log10(n)/log10(2);

How to unbind a listener that is calling event.preventDefault() (using jQuery)?

In my case:


$('#some_link').unbind('click'); worked as the only method to restore the default action.

As seen over here:

How to run a script at a certain time on Linux?

Cron is good for something that will run periodically, like every Saturday at 4am. There's also anacron, which works around power shutdowns, sleeps, and whatnot. As well as at.

But for a one-off solution, that doesn't require root or anything, you can just use date to compute the seconds-since-epoch of the target time as well as the present time, then use expr to find the difference, and sleep that many seconds.

100% width table overflowing div container

Try adding to td:

display: -webkit-box; // to make td as block
word-break: break-word; // to make content justify

overflowed tds will align with new row.

How do I show multiple recaptchas on a single page?

To add a bit to raphadko's answer: since you have multiple captchas (on one page), you can't use the (universal) g-recaptcha-response POST parameter (because it holds only one captcha's response). Instead, you should use grecaptcha.getResponse(opt_widget_id) call for each captcha. Here's my code (provided each captcha is inside its form):


<form ... />

<div id="RecaptchaField1"></div>

<div class="field">
  <input type="hidden" name="grecaptcha" id="grecaptcha" />



<script src="" async defer></script>


var CaptchaCallback = function(){
    var widgetId;

    $('[id^=RecaptchaField]').each(function(index, el) {

         widgetId = grecaptcha.render(, {'sitekey' : 'your_site_key'});

         $(el).closest("form").submit(function( event ) {

            this.grecaptcha.value = "{\"" + index + "\" => \"" + grecaptcha.getResponse(widgetId) + "\"}"


Notice that I apply the event delegation (see refresh DOM after append element ) to all the dynamically modified elements. This binds every individual captha's response to its form submit event.

postgresql: INSERT INTO ... (SELECT * ...)

This notation (first seen here) looks useful too:

insert into postagem (
) select
  idcatolico ,

Selecting rows where remainder (modulo) is 1 after division by 2?

At least some versions of SQL (Oracle, Informix, DB2, ISO Standard) support:

WHERE MOD(value, 2) = 1

MySQL supports '%' as the modulus operator:

WHERE value % 2 = 1

Set angular scope variable in markup

ngInit can help to initialize variables.

<div ng-app='app'>
    <div ng-controller="MyController" ng-init="myVar='test'">

jsfiddle example

IOException: read failed, socket might closed - Bluetooth on Android 4.3

well, i had the same problem with my code, and it's because since android 4.2 bluetooth stack has changed. so my code was running fine on devices with android < 4.2 , on the other devices i was getting the famous exception "read failed, socket might closed or timeout, read ret: -1"

The problem is with the socket.mPort parameter. When you create your socket using socket = device.createRfcommSocketToServiceRecord(SERIAL_UUID); , the mPort gets integer value "-1", and this value seems doesn't work for android >=4.2 , so you need to set it to "1". The bad news is that createRfcommSocketToServiceRecord only accepts UUID as parameter and not mPort so we have to use other aproach. The answer posted by @matthes also worked for me, but i simplified it: socket =(BluetoothSocket) device.getClass().getMethod("createRfcommSocket", new Class[] {int.class}).invoke(device,1);. We need to use both socket attribs , the second one as a fallback.

So the code is (for connecting to a SPP on an ELM327 device):

BluetoothAdapter btAdapter = BluetoothAdapter.getDefaultAdapter();

    if (btAdapter.isEnabled()) {
        SharedPreferences prefs_btdev = getSharedPreferences("btdev", 0);
        String btdevaddr=prefs_btdev.getString("btdevaddr","?");

        if (btdevaddr != "?")
            BluetoothDevice device = btAdapter.getRemoteDevice(btdevaddr);

            UUID SERIAL_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb"); // bluetooth serial port service
            //UUID SERIAL_UUID = device.getUuids()[0].getUuid(); //if you don't know the UUID of the bluetooth device service, you can get it like this from android cache

            BluetoothSocket socket = null;

            try {
                socket = device.createRfcommSocketToServiceRecord(SERIAL_UUID);
            } catch (Exception e) {Log.e("","Error creating socket");}

            try {
            } catch (IOException e) {
                try {
                    Log.e("","trying fallback...");

                    socket =(BluetoothSocket) device.getClass().getMethod("createRfcommSocket", new Class[] {int.class}).invoke(device,1);

             catch (Exception e2) {
                 Log.e("", "Couldn't establish Bluetooth connection!");
            Log.e("","BT device not selected");

How to check if a variable is both null and /or undefined in JavaScript

You can wrap it in your own function:

function isNullAndUndef(variable) {

    return (variable !== null && variable !== undefined);

Beginner Python Practice?

I always find it easier to learn a language in a specific problem domain. You might try looking at Django and doing the tutorial. This will give you a very light-weight intro to both Python and to a web framework (a very well-documented one) that is 100% Python.

Then do something in your field(s) of expertise -- graph generation, or whatever -- and tie that into a working framework to see if you got it right. My universe tends to be computational linguistics and there are a number of Python-based toolkits to help get you started. E.g. Natural Language Toolkit.

Just a thought.

Filter dict to contain only certain keys?

You can do that with project function from my funcy library:

from funcy import project
small_dict = project(big_dict, keys)

Also take a look at select_keys.

Find if a String is present in an array

Use Arrays.asList() to wrap the array in a List<String>, which does have a contains() method:


Trying to get the average of a count resultset

You just can put your query as a subquery:

SELECT avg(count)
    SELECT COUNT (*) AS Count
      FROM Table T
     WHERE T.Update_time =
               (SELECT MAX (B.Update_time )
                  FROM Table B
                 WHERE (B.Id = T.Id))
    GROUP BY T.Grouping
    ) as counts

Edit: I think this should be the same:

SELECT count(*) / count(distinct T.Grouping)
  FROM Table T
 WHERE T.Update_time =
           (SELECT MAX (B.Update_time)
              FROM Table B
             WHERE (B.Id = T.Id))

How to select a single column with Entity Framework?

I'm a complete noob on Entity but this is how I would do it in theory...

var name = yourDbContext.MyTable.Find(1).Name;

If It's A Primary Key.

-- OR --

var name = yourDbContext.MyTable.SingleOrDefault(mytable => mytable.UserId == 1).Name;

-- OR --

For whole Column:

var names = yourDbContext.MyTable
.Where(mytable => mytable.UserId == 1)
.Select(column => column.Name); //You can '.ToList();' this....

But "oh Geez Rick, What do I know..."

Creating a timer in python

mins = minutes + 1

should be

minutes = minutes + 1


minutes = 0

needs to be outside of the while loop.

Oracle select most recent date record

select *
from (select
  staff_id, site_id, pay_level, date, 
  rank() over (partition by staff_id order by date desc) r
  from owner.table
  where end_enrollment_date is null
where r = 1

How can I generate a list or array of sequential integers in Java?

This one might works for you....

void List<Integer> makeSequence(int begin, int end) {

  AtomicInteger ai=new AtomicInteger(begin);
  List<Integer> ret = new ArrayList(end-begin+1);

  while ( end-->begin) {


  return ret;  

Python Script to convert Image into Byte array

Use bytearray:

with open("img.png", "rb") as image:
  f =
  b = bytearray(f)
  print b[0]

You can also have a look at struct which can do many conversions of that kind.

Fixed page header overlaps in-page anchors

You can do this with jQuery:

var offset = $('.target').offset();
var scrollto = - 50; // fixed_top_bar_height = 50px
$('html, body').animate({scrollTop:scrollto}, 0);

I don't have "Dynamic Web Project" option in Eclipse new Project wizard

Maybe Eclipse WTP plugin has been accidently removed. Have you tried re-installing WTP using this location ? If I were you I would have reinstall Eclipse from strach or even better try Spring ToolSuite which integrates with Google Plugin for Eclipse seamlessly (usign Extenstions tab on STS Dashboard)

How to put img inline with text

Please make use of the code below to display images inline:

<img style='vertical-align:middle;' src='somefolder/icon.gif'>
<div style='vertical-align:middle; display:inline;'>
Your text here

Convert UTC Epoch to local date

The Easiest Way

If you have the unix epoch in milliseconds, in my case - 1601209912824

  1. convert it into a Date Object as so
const dateObject = new Date(milliseconds)
const humanDateFormat = dateObject.toString() 

output -

Sun Sep 27 2020 18:01:52 GMT+0530 (India Standard Time)
  1. if you want the date in UTC -
const dateObject = new Date(milliseconds)
const humanDateFormat = dateObject.toUTCString() 
  1. Now you can format it as you please.

How to use Console.WriteLine in ASP.NET (C#) during debug?

Make sure you start your application in Debug mode (F5), not without debugging (Ctrl+F5) and then select "Show output from: Debug" in the Output panel in Visual Studio.

CSS div 100% height

CSS Flexbox was designed to simplify creating these types of layouts.

html {
  height: 100%;

body {
  height: 100%;
  display: flex;

.Content {
  flex-grow: 1;

.Sidebar {
  width: 290px;
  flex-shrink: 0;
<div class="Content" style="background:#bed">Content</div>
<div class="Sidebar" style="background:#8cc">Sidebar</div>

What is the perfect counterpart in Python for "while not EOF"

In addition to @dawg's great answer, the equivalent solution using walrus operator (Python >= 3.8):

with open(filename, 'rb') as f:
    while buf :=

How do I count a JavaScript object's attributes?

There's no easy answer, because Object — which every object in JavaScript derives from — includes many attributes automatically, and the exact set of attributes you get depends on the particular interpreter and what code has executed before yours. So, you somehow have to separate the ones you defined from those you got "for free."

Here's one way:

var foo = {"key1": "value1", "key2": "value2", "key3": "value3"};
Object.prototype.foobie = 'bletch'; // add property to foo that won't be counted

var count = 0;
for (var k in foo) {
    if (foo.hasOwnProperty(k)) {
alert("Found " + count + " properties specific to foo");

The second line shows how other code can add properties to all Object derivatives. If you remove the hasOwnProperty() check inside the loop, the property count will go up to at least 4. On a page with other JavaScript besides this code, it could be higher than 4, if that other code also modifies the Object prototype.

detect key press in python?

As OP mention about raw_input - that means he want cli solution. Linux: curses is what you want (windows PDCurses). Curses, is an graphical API for cli software, you can achieve more than just detect key events.

This code will detect keys until new line is pressed.

import curses
import os

def main(win):
    win.addstr("Detected key:")
    while 1:          
           key = win.getkey()         
           win.addstr("Detected key:")
           if key == os.linesep:
        except Exception as e:
           # No input   


How do I upgrade the Python installation in Windows 10?

Just install python newest version's installer it will automatically detect your python version and will say upgrade python and starts upgrading

when exactly are we supposed to use "public static final String"?

Usually for defining constants, that you reuse at many places making it single point for change, used within single class or shared across packages. Making a variable final avoid accidental changes.

While, Do While, For loops in Assembly Language (emu8086)


For-loop in C:

for(int x = 0; x<=3; x++)
    //Do something!

The same loop in 8086 assembler:

        xor cx,cx   ; cx-register is the counter, set to 0
loop1   nop         ; Whatever you wanna do goes here, should not change cx
        inc cx      ; Increment
        cmp cx,3    ; Compare cx to the limit
        jle loop1   ; Loop while less or equal

That is the loop if you need to access your index (cx). If you just wanna to something 0-3=4 times but you do not need the index, this would be easier:

        mov cx,4    ; 4 iterations
loop1   nop         ; Whatever you wanna do goes here, should not change cx
        loop loop1  ; loop instruction decrements cx and jumps to label if not 0

If you just want to perform a very simple instruction a constant amount of times, you could also use an assembler-directive which will just hardcore that instruction

times 4 nop


Do-while-loop in C:

int x=1;
    //Do something!

The same loop in assembler:

        mov ax,1
loop1   nop         ; Whatever you wanna do goes here
        cmp ax,1    ; Check wether cx is 1
        je loop1    ; And loop if equal


While-loop in C:

    //Do something

The same loop in assembler:

        jmp loop1   ; Jump to condition first
cloop1  nop         ; Execute the content of the loop
loop1   cmp ax,1    ; Check the condition
        je cloop1   ; Jump to content of the loop if met

For the for-loops you should take the cx-register because it is pretty much standard. For the other loop conditions you can take a register of your liking. Of course replace the no-operation instruction with all the instructions you wanna perform in the loop.

T-test in Pandas

I simplify the code a little bit.

from scipy.stats import ttest_ind
ttest_ind(*my_data.groupby('Category')['value'].apply(lambda x:list(x)))

Node.js - use of module.exports as a constructor

The example code is:

in main

square(width,function (data)

using the following may works

exports.square = function(width,callback)
     var aa = new Object();
     callback(aa.squareVal = width * width);    

Up, Down, Left and Right arrow keys do not trigger KeyDown event

In order to capture keystrokes in a Forms control, you must derive a new class that is based on the class of the control that you want, and you override the ProcessCmdKey().

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    //handle your keys here

Example :

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
    //capture up arrow key
    if (keyData == Keys.Up )
        MessageBox.Show("You pressed Up arrow key");
        return true;

    return base.ProcessCmdKey(ref msg, keyData);

Full source...Arrow keys in C#


Checking if a variable exists in javascript

if (variable) can be used if variable is guaranteed to be an object, or if false, 0, etc. are considered "default" values (hence equivalent to undefined or null).

typeof variable == 'undefined' can be used in cases where a specified null has a distinct meaning to an uninitialised variable or property. This check will not throw and error is variable is not declared.

How to use NULL or empty string in SQL

by this function:

ALTER FUNCTION [dbo].[isnull](@input nvarchar(50),@ret int = 0)

    return (case when @input='' then @ret when @input is null then @ret else @input end)


and use this:


why windows 7 task scheduler task fails with error 2147942667

This can happen for more than one reason. In my case this happened due to a permissions issue. The user that the task was running as didn't have permission to write to the logs directory so it failed with this error.

Calling virtual functions inside constructors

As has been pointed out, the objects are created base-down upon construction. When the base object is being constructed, the derived object does not exist yet, so a virtual function override cannot work.

However, this can be solved with polymorphic getters that use static polymorphism instead of virtual functions if your getters return constants, or otherwise can be expressed in a static member function, This example uses CRTP (

template<typename DerivedClass>
class Base
    inline Base() :

    inline int fooSq() {
        return foo * foo;

    const int foo;

class A : public Base<A>
    inline static int getFoo() { return 1; }

class B : public Base<B>
    inline static int getFoo() { return 2; }

class C : public Base<C>
    inline static int getFoo() { return 3; }

int main()
    A a;
    B b;
    C c;

    std::cout << a.fooSq() << ", " << b.fooSq() << ", " << c.fooSq() << std::endl;

    return 0;

With the use of static polymorphism, the base class knows which class' getter to call as the information is provided at compile-time.

Difference between int32, int, int32_t, int8 and int8_t

Between int32 and int32_t, (and likewise between int8 and int8_t) the difference is pretty simple: the C standard defines int8_t and int32_t, but does not define anything named int8 or int32 -- the latter (if they exist at all) is probably from some other header or library (most likely predates the addition of int8_t and int32_t in C99).

Plain int is quite a bit different from the others. Where int8_t and int32_t each have a specified size, int can be any size >= 16 bits. At different times, both 16 bits and 32 bits have been reasonably common (and for a 64-bit implementation, it should probably be 64 bits).

On the other hand, int is guaranteed to be present in every implementation of C, where int8_t and int32_t are not. It's probably open to question whether this matters to you though. If you use C on small embedded systems and/or older compilers, it may be a problem. If you use it primarily with a modern compiler on desktop/server machines, it probably won't be.

Oops -- missed the part about char. You'd use int8_t instead of char if (and only if) you want an integer type guaranteed to be exactly 8 bits in size. If you want to store characters, you probably want to use char instead. Its size can vary (in terms of number of bits) but it's guaranteed to be exactly one byte. One slight oddity though: there's no guarantee about whether a plain char is signed or unsigned (and many compilers can make it either one, depending on a compile-time flag). If you need to ensure its being either signed or unsigned, you need to specify that explicitly.

Output data with no column headings using PowerShell

add the parameter -expandproperty after the select-object, it will return only data without header.

How to get a list of images on docker registry v2

If some on get this far.

Taking what others have already said above. Here is a one-liner that puts the answer into a text file formatted, json.

curl "http://mydocker.registry.domain/v2/_catalog?n=2000" | jq . - > /tmp/registry.lst

This looks like

  "repositories": [

You might need to change the `?n=xxxx' to match how many containers you have.

Next is a way to automatically remove old and unused containers.

How can I define fieldset border color?

If you don't want 3D border use:

border:#f00 1px solid;

How do I add a new column to a Spark DataFrame (using PySpark)?

You cannot add an arbitrary column to a DataFrame in Spark. New columns can be created only by using literals (other literal types are described in How to add a constant column in a Spark DataFrame?)

from pyspark.sql.functions import lit

df = sqlContext.createDataFrame(
    [(1, "a", 23.0), (3, "B", -23.0)], ("x1", "x2", "x3"))

df_with_x4 = df.withColumn("x4", lit(0))

## +---+---+-----+---+
## | x1| x2|   x3| x4|
## +---+---+-----+---+
## |  1|  a| 23.0|  0|
## |  3|  B|-23.0|  0|
## +---+---+-----+---+

transforming an existing column:

from pyspark.sql.functions import exp

df_with_x5 = df_with_x4.withColumn("x5", exp("x3"))

## +---+---+-----+---+--------------------+
## | x1| x2|   x3| x4|                  x5|
## +---+---+-----+---+--------------------+
## |  1|  a| 23.0|  0| 9.744803446248903E9|
## |  3|  B|-23.0|  0|1.026187963170189...|
## +---+---+-----+---+--------------------+

included using join:

from pyspark.sql.functions import exp

lookup = sqlContext.createDataFrame([(1, "foo"), (2, "bar")], ("k", "v"))
df_with_x6 = (df_with_x5
    .join(lookup, col("x1") == col("k"), "leftouter")
    .withColumnRenamed("v", "x6"))

## +---+---+-----+---+--------------------+----+
## | x1| x2|   x3| x4|                  x5|  x6|
## +---+---+-----+---+--------------------+----+
## |  1|  a| 23.0|  0| 9.744803446248903E9| foo|
## |  3|  B|-23.0|  0|1.026187963170189...|null|
## +---+---+-----+---+--------------------+----+

or generated with function / udf:

from pyspark.sql.functions import rand

df_with_x7 = df_with_x6.withColumn("x7", rand())

## +---+---+-----+---+--------------------+----+-------------------+
## | x1| x2|   x3| x4|                  x5|  x6|                 x7|
## +---+---+-----+---+--------------------+----+-------------------+
## |  1|  a| 23.0|  0| 9.744803446248903E9| foo|0.41930610446846617|
## |  3|  B|-23.0|  0|1.026187963170189...|null|0.37801881545497873|
## +---+---+-----+---+--------------------+----+-------------------+

Performance-wise, built-in functions (pyspark.sql.functions), which map to Catalyst expression, are usually preferred over Python user defined functions.

If you want to add content of an arbitrary RDD as a column you can

Difference between filter and filter_by in SQLAlchemy

We actually had these merged together originally, i.e. there was a "filter"-like method that accepted *args and **kwargs, where you could pass a SQL expression or keyword arguments (or both). I actually find that a lot more convenient, but people were always confused by it, since they're usually still getting over the difference between column == expression and keyword = expression. So we split them up.

'node' is not recognized as an internal or an external command, operable program or batch file while using phonegap/cordova

If you install Node using the windows installer, there is nothing you have to do. It adds path to node and npm.

You can also use Windows setx command for changing system environment variables. No reboot is required. Just logout/login. Or just open a new cmd window, if you want to see the changing there.

setx PATH "%PATH%;C:\Program Files\nodejs"

Can Android Studio be used to run standard Java projects?

Tested in Android Studio 0.8.14:
I was able to get a standard project running with minimal steps in this way:

  • In an open Android Studio project, click File > New Module.
  • Click More Modules > Java Library > Next, then fill in whatever you prefer for the names.
  • A new module will appear as a folder on the same level as your "app" folder in the Project Structure. Open it and open the new Java class file.

    You can then add your code, and choose Build > Run 'YourClassName'. Presto, your code is running with no Android device!

  • How to make button look like a link?

    The code of the accepted answer works for most cases, but to get a button that really behaves like a link you need a bit more code. It is especially tricky to get the styling of focused buttons right on Firefox (Mozilla).

    The following CSS ensures that anchors and buttons have the same CSS properties and behave the same on all common browsers:

    button {
      align-items: normal;
      background-color: rgba(0,0,0,0);
      border-color: rgb(0, 0, 238);
      border-style: none;
      box-sizing: content-box;
      color: rgb(0, 0, 238); 
      cursor: pointer;
      display: inline;
      font: inherit;
      height: auto;
      padding: 0;
      perspective-origin: 0 0;
      text-align: start;
      text-decoration: underline;
      transform-origin: 0 0;
      width: auto;
      -moz-appearance: none;
      -webkit-logical-height: 1em; /* Chrome ignores auto, so we have to use this hack to set the correct height  */
      -webkit-logical-width: auto; /* Chrome ignores auto, but here for completeness */
    /* Mozilla uses a pseudo-element to show focus on buttons, */
    /* but anchors are highlighted via the focus pseudo-class. */
    @supports (-moz-appearance:none) { /* Mozilla-only */
      button::-moz-focus-inner { /* reset any predefined properties */ 
        border: none;
        padding: 0;
      button:focus { /* add outline to focus pseudo-class */
        outline-style: dotted;
        outline-width: 1px;

    The example above only modifies button elements to improve readability, but it can easily be extended to modify input[type="button"], input[type="submit"] and input[type="reset"] elements as well. You could also use a class, if you want to make only certain buttons look like anchors.

    See this JSFiddle for a live-demo.

    Please also note that this applies the default anchor-styling to buttons (e.g. blue text-color). So if you want to change the text-color or anything else of anchors & buttons, you should do this after the CSS above.

    The original code (see snippet) in this answer was completely different and incomplete.

    /* Obsolete code! Please use the code of the updated answer. */_x000D_
    input[type="button"], input[type="button"]:focus, input[type="button"]:active,  _x000D_
    button, button:focus, button:active {_x000D_
     /* Remove all decorations to look like normal text */_x000D_
     background: none;_x000D_
     border: none;_x000D_
     display: inline;_x000D_
     font: inherit;_x000D_
     margin: 0;_x000D_
     padding: 0;_x000D_
     outline: none;_x000D_
     outline-offset: 0;_x000D_
     /* Additional styles to look like a link */_x000D_
     color: blue;_x000D_
     cursor: pointer;_x000D_
     text-decoration: underline;_x000D_
    /* Remove extra space inside buttons in Firefox */_x000D_
    button::-moz-focus-inner {_x000D_
        border: none;_x000D_
        padding: 0;_x000D_

    'Best' practice for restful POST response

    Returning the whole object on an update would not seem very relevant, but I can hardly see why returning the whole object when it is created would be a bad practice in a normal use case. This would be useful at least to get the ID easily and to get the timestamps when relevant. This is actually the default behavior got when scaffolding with Rails.

    I really do not see any advantage to returning only the ID and doing a GET request after, to get the data you could have got with your initial POST.

    Anyway as long as your API is consistent I think that you should choose the pattern that fits your needs the best. There is not any correct way of how to build a REST API, imo.

    Getting the parent div of element

    Knowing the parent of an element is useful when you are trying to position them out the "real-flow" of elements.

    Below given code will output the id of parent of element whose id is provided. Can be used for misalignment diagnosis.

    <!-- Patch of code to find parent -->
    <p id="demo">Click the button </p>
    <button onclick="parentFinder()">Find Parent</button>
    function parentFinder()
        var x=document.getElementById("demo"); 
        var y=document.getElementById("*id of Element you want to know parent of*");;
    <!-- Patch ends -->

    What is the right way to POST multipart/form-data using curl?

    I had a hard time sending a multipart HTTP PUT request with curl to a Java backend. I simply tried

    curl -X PUT URL \
       --header 'Content-Type: multipart/form-data; boundary=---------BOUNDARY' \
       --data-binary @file

    and the content of the file was

    Content-Disposition: form-data; name="name1"
    Content-Type: application/xml;version=1.0;charset=UTF-8
    Content-Disposition: form-data; name="name2"
    Content-Type: text/plain

    but I always got an error that the boundary was incorrect. After some Java backend debugging I found out that the Java implementation was adding a \r\n-- as a prefix to the boundary, so after changing my input file to

                              <-- here's the CRLF
    -------------BOUNDARY       <-- added '--' at the beginning
    -------------BOUNDARY       <-- added '--' at the beginning
    -------------BOUNDARY--     <-- added '--' at the beginning

    everything works fine!


    Add a newline (CRLF \r\n) at the beginning of the multipart boundary content and -- at the beginning of the boundaries and try again.

    Maybe you are sending a request to a Java backend that needs this changes in the boundary.

    No increment operator (++) in Ruby?

    Ruby has no pre/post increment/decrement operator. For instance, x++ or x-- will fail to parse. More importantly, ++x or --x will do nothing! In fact, they behave as multiple unary prefix operators: -x == ---x == -----x == ...... To increment a number, simply write x += 1.

    Taken from "Things That Newcomers to Ruby Should Know " (archive, mirror)

    That explains it better than I ever could.

    EDIT: and the reason from the language author himself (source):

    1. ++ and -- are NOT reserved operator in Ruby.
    2. C's increment/decrement operators are in fact hidden assignment. They affect variables, not objects. You cannot accomplish assignment via method. Ruby uses +=/-= operator instead.
    3. self cannot be a target of assignment. In addition, altering the value of integer 1 might cause severe confusion throughout the program.

    Java synchronized method lock on object, or method?

    From "The Java™ Tutorials" on synchronized methods:

    First, it is not possible for two invocations of synchronized methods on the same object to interleave. When one thread is executing a synchronized method for an object, all other threads that invoke synchronized methods for the same object block (suspend execution) until the first thread is done with the object.

    From "The Java™ Tutorials" on synchronized blocks:

    Synchronized statements are also useful for improving concurrency with fine-grained synchronization. Suppose, for example, class MsLunch has two instance fields, c1 and c2, that are never used together. All updates of these fields must be synchronized, but there's no reason to prevent an update of c1 from being interleaved with an update of c2 — and doing so reduces concurrency by creating unnecessary blocking. Instead of using synchronized methods or otherwise using the lock associated with this, we create two objects solely to provide locks.

    (Emphasis mine)

    Suppose you have 2 non-interleaving variables. So you want to access to each one from a different threads at the same time. You need to define the lock not on the object class itself, but on the class Object like below (example from the second Oracle link):

    public class MsLunch {
        private long c1 = 0;
        private long c2 = 0;
        private Object lock1 = new Object();
        private Object lock2 = new Object();
        public void inc1() {
            synchronized(lock1) {
        public void inc2() {
            synchronized(lock2) {

    ERROR 1049 (42000): Unknown database

    Its a common error which happens when we try to access a database which doesn't exist. So create the database using

    CREATE DATABASE blog_development;

    The error commonly occours when we have dropped the database using

    DROP DATABASE blog_development;

    and then try to access the database.

    Show Curl POST Request Headers? Is there a way to do this?

    You can see the information regarding the transfer by doing:

    curl_setopt($curl_exect, CURLINFO_HEADER_OUT, true);

    before the request, and

    $information = curl_getinfo($curl_exect);

    after the request


    You can also use the CURLOPT_HEADER in your curl_setopt

    curl_setopt($curl_exect, CURLOPT_HEADER, true);
    $httpcode = curl_getinfo($c, CURLINFO_HTTP_CODE);
    return $httpcode == 200;

    These are just some methods of using the headers.

    Can I make a function available in every controller in angular?

    You can also combine them I guess:

    <!doctype html>
    <html ng-app="myApp">
        <script src=""></script>
        <script src=""></script>
        <script type="text/javascript">
            var myApp = angular.module('myApp', []);
            myApp.factory('myService', function() {
                return {
                    foo: function() {
                        alert("I'm foo!");
  $rootScope, myService) {
                $rootScope.appData = myService;
            myApp.controller('MainCtrl', ['$scope', function($scope){
    <body ng-controller="MainCtrl">
        <button ng-click="">Call foo</button>

    MySQL SELECT query string matching

    Just turn the LIKE around

    SELECT * FROM customers
    WHERE 'Robert Bob Smith III, PhD.' LIKE CONCAT('%',name,'%')

    CryptographicException 'Keyset does not exist', but only through WCF

    I found some missing information that helped me get my WCF service with Message level security past the "Keyset does not exist" that I kept running into despite granting permissions to all the keys generated from the examples on the internet.

    I finally imported the private key into the trusted people store on local machine and then granted the private key the correct permissions.

    This filled in the blanks for me and finally allowed me to implement the WCF service with Message level security. I am building a WCF that must be HIPPA compliant.

    How to create exe of a console application

    For .NET Core 2.2 you can publish the application and set the target to be a self-contained executable.

    In Visual Studio right click your console application project. Select publish to folder and set the profile settings like so:

    Visual Studio Publish Menu

    You'll find your compiled code with the .exe in the publish folder.

    Aligning text and image on UIButton with imageEdgeInsets and titleEdgeInsets

    In Xcode 8.0 you can simply do it by changing insets in size inspector.

    Select the UIButton -> Attributes Inspector -> go to size inspector and modify the content, image and title insets.

    enter image description here

    And if you want to change image on right side you can simply change the semantic property to Force Right-to-left in Attribute inspector .

    enter image description here

    jQuery "blinking highlight" effect on div?

    If you are not already using the Jquery UI library and you want to mimic the effect what you can do is very simple


    you can also play around with the numbers to get a faster or slower one to fit your design better.

    This can also be a global jquery function so you can use the same effect across the site. Also note that if you put this code in a for loop you can have 1 milion pulses so therefore you are not restricted to the default 6 or how much the default is.

    EDIT: Adding this as a global jQuery function

    $.fn.Blink = function (interval = 100, iterate = 1) {
        for (i = 1; i <= iterate; i++)

    Blink any element easily from your site using the following

    $('#myElement').Blink(); // Will Blink once
    $('#myElement').Blink(500); // Will Blink once, but slowly
    $('#myElement').Blink(100, 50); // Will Blink 50 times once

    What is Gradle in Android Studio?

    In Android Studio, Gradle is used for building our android application projects, hence playing the role of a build system. Before Android Studio, in Eclipse we used to compile and build the applications using command line tool which was soon taken over by GUI based steps to build and run Android Applications in eclipse using ANT. Every android application development tool has to compile resources, java source code, external libraries and combine them into a final APK.

    Gradle is a build system, which is responsible for code compilation, testing, deployment and conversion of the code into .dex files and hence running the app on the device.

    As Android Studio comes with Gradle system pre-installed, there is no need to install additional runtime softwares to build our project. Whenever you click on Run button in android studio, a gradle task automatically triggers and starts building the project and after gradle completes its task, app starts running in AVD or in the connected device.

    A build system like Gradle is not a compiler, linker etc, but it controls and supervises the operation of compilation, linking of files, running test cases, and eventually bundling the code into an apk file for your Android Application.

    There are two build.gradle files for every android studio project of which, one is for application and other is for project level(module level) build files.

    In the build process, the compiler takes the source code, resources, external libraries JAR files and AndroidManifest.xml(which contains the meta-data about the application) and convert them into .dex(Dalvik Executable files) files, which includes bytecode. That bytecode is supported by all android devices to run your app. Then APK Manager combines the .dex files and all other resources into single apk file. APK Packager signs debug or release apk using respective debug or release keystore.

    Debug apk is generally used for testing purpose or we can say that it is used at development stage only. When your app is complete with desired features and you are ready to publish your application for external use then you require a Release apk signed using a release keystore.

    Now lets shed some light on the gradle files.

    setting.gradle The setting.gradle(Gradle setting) file is used to specify all the modules used in your app.

    build.gradle (project level) The Top level (module) build.gradle file is project level build file, which defines build configurations at project level. This file applies configurations to all the modules in android application project.

    build.gradle (application level) The Application level build.gradle file is located in each module of the android project. This file includes your package name as applicationID, version name(apk version), version code, minimum and target sdk for a specific application module. When you are including external libraries(not the jar files) then you need to mention it in the app level gradle file to include them in your project as dependencies of the application.

    Note: If a certain application is developed in variations for individual modules like, Smart Phone, Tablet or TV then separate gradle files must to be created for all. You can even start your gradle system through command line tool. Following commands are used for it:

    ./gradlew build - (build project)
    ./gradlew clean build - (build project complete scratch)
    ./gradlew clean build - (run the test)
    ./gradlew wrapper - (to see all the available tasks)

    Node.js: Python not found exception due to node-sass and node-gyp

    My answer might not apply to everyone. Node version: v10.16.0 NPM: 6.9.0

    I was having a lot of trouble using node-sass and node-sass-middleware. They are interesting packages because they are widely used (millions of downloads weekly), but their githubs show a limited dependencies and coverage. I was updating an older platform I'd been working on.

    What I ended up having to do was:

    1) Manually Delete node_modules

    2) Manually Delete package-lock.json

    3) sudo npm install node-sass --unsafe-perm=true --allow-root

    4) sudo npm install node-sass-middleware --unsafe-perm=true --allow-root

    I had the following help, thanks!

    Pre-built binaries not found for [email protected] and [email protected]

    Error: EACCES: permission denied when trying to install ESLint using npm

    How to define a List bean in Spring?

    Stacker posed a great answer, I would go one step farther to make it more dynamic and use Spring 3 EL Expression.

    <bean id="listBean" class="java.util.ArrayList">

    I was trying to figure out how I could do this with the util:list but couldn't get it work due to conversion errors.

    Angularjs: input[text] ngChange fires while the value is changing

    Isn't using $scope.$watch to reflect the changes of scope variable better?

    Git undo changes in some files


    git commit FILE

    will commit just FILE. Then you can use

    git reset --hard

    to undo local changes in other files.

    There may be other ways too that I don't know about...

    edit: or, as NicDumZ said, git-checkout just the files you want to undo the changes on (the best solution depends on wether there are more files to commit or more files to undo :-)

    Accessing Objects in JSON Array (JavaScript)

    Use a loop

    for(var i = 0; i < obj.length; ++i){
       //do something with obj[i]
       for(var ind in obj[i]) {
            for(var vals in obj[i][ind]){
                console.log(vals, obj[i][ind][vals]);


    mysql data directory location

    If the software is Sequel pro the default install mysql on Mac OSX has data located here:


    Ideal way to cancel an executing AsyncTask

    If you're doing computations:

    • You have to check isCancelled() periodically.

    If you're doing a HTTP request:

    • Save the instance of your HttpGet or HttpPost somewhere (eg. a public field).
    • After calling cancel, call request.abort(). This will cause IOException be thrown inside your doInBackground.

    In my case, I had a connector class which I used in various AsyncTasks. To keep it simple, I added a new abortAllRequests method to that class and called this method directly after calling cancel.

    How can I clear the NuGet package cache using the command line?

    Clearing the cache

    With dotnet core cli

    dotnet nuget locals all --clear

    With Visual Studio 2017

    1. Go to menu Tools ? NuGet Package Manager ? Package Manager Settings.
    2. Click Clear All NuGet Cache(s):

    visual studio NuGet Package Manager General settings screenshot

    With the nuget cli

    Download and install the NuGet command line tool.

    nuget locals all -clear

    With windows command line

    del %LOCALAPPDATA%\NuGet\Cache\*.nupkg /q

    (can be used in a .bat file)

    With PowerShell

    rm $env:LOCALAPPDATA\NuGet\Cache\*.nupkg

    Or 'quiet' mode (without error messages):

    rm $env:LOCALAPPDATA\NuGet\Cache\*.nupkg 2> $null

    Cache location





    Build server

    %windir%/ServiceProfiles/[account under build service runs]\AppData\Local\NuGet\Cache



    This answer is a rollup of all the existing answers for your convenience

    How to convert text column to datetime in SQL

    In SQL Server , cast text as datetime

    select cast('5/21/2013 9:45:48' as datetime)

    Converting integer to binary in python

    Assuming you want to parse the number of digits used to represent from a variable which is not always constant, a good way will be to use numpy.binary.

    could be useful when you apply binary to power sets

    import numpy as np
    np.binary_repr(6, width=8)

    C# HttpClient 4.5 multipart/form-data upload

    Here's a complete sample that worked for me. The boundary value in the request is added automatically by .NET.

    var url = "http://localhost/api/v1/yourendpointhere";
    var filePath = @"C:\path\to\image.jpg";
    HttpClient httpClient = new HttpClient();
    MultipartFormDataContent form = new MultipartFormDataContent();
    FileStream fs = File.OpenRead(filePath);
    var streamContent = new StreamContent(fs);
    var imageContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
    imageContent.Headers.ContentType = MediaTypeHeaderValue.Parse("multipart/form-data");
    form.Add(imageContent, "image", Path.GetFileName(filePath));
    var response = httpClient.PostAsync(url, form).Result;

    Hibernate: How to set NULL query-parameter value with HQL?

    this seems to work as wel ->

    public List<SomeObject> findAllForThisSpecificThing(String thing) {
        final Query query = entityManager.createQuery(
                "from " + getDomain().getSimpleName() + " t  where t.thing = " + ((thing == null) ? " null" : " :thing"));
        if (thing != null) {
            query.setParameter("thing", thing);
        return query.getResultList();

    Btw, I'm pretty new at this, so if for any reason this isn't a good idea, let me know. Thanks.

    Java: how do I get a class literal from a generic type?

    Due to the exposed fact that Class literals doesn't have generic type information, I think you should assume that it will be impossible to get rid of all the warnings. In a way, using Class<Something> is the same as using a collection without specifying the generic type. The best I could come out with was:

    private <C extends A<C>> List<C> getList(Class<C> cls) {
        List<C> res = new ArrayList<C>();
        // "snip"... some stuff happening in here, using cls
        return res;
    public <C extends A<C>> List<A<C>> getList() {
        return getList(A.class);

    How do I set default terminal to terminator?

    In xfce (e.g. on Arch Linux) you can change the parameter TerminalEmulator:




    The next time you want to open a terminal window, xfce will ask you to choose an emulator. You can just pick /usr/bin/terminator.

    System Defaults


    User Defaults


    Bash script error [: !=: unary operator expected

    Or for what seems like rampant overkill, but is actually simplistic ... Pretty much covers all of your cases, and no empty string or unary concerns.

    In the case the first arg is '-v', then do your conditional ps -ef, else in all other cases throw the usage.

    case $1 in
      '-v') if [ "$1" = -v ]; then
             echo "`ps -ef | grep -v '\['`"
             echo "`ps -ef | grep '\[' | grep root`"
         *) echo "usage: $0 [-v]"
            exit 1;; #It is good practice to throw a code, hence allowing $? check

    If one cares not where the '-v' arg is, then simply drop the case inside a loop. The would allow walking all the args and finding '-v' anywhere (provided it exists). This means command line argument order is not important. Be forewarned, as presented, the variable arg_match is set, thus it is merely a flag. It allows for multiple occurrences of the '-v' arg. One could ignore all other occurrences of '-v' easy enough.

    usage ()
      echo "usage: $0 [-v]"
      exit 1
    unset arg_match
    for arg in $*
      case $arg in
        '-v') if [ "$arg" = -v ]; then
               echo "`ps -ef | grep -v '\['`"
               echo "`ps -ef | grep '\[' | grep root`"
              arg_match=1;; # this is set, but could increment.
           *) ;;
    if [ ! $arg_match ]

    But, allow multiple occurrences of an argument is convenient to use in situations such as:

    $ adduser -u:sam -s -f -u:bob -trace -verbose

    We care not about the order of the arguments, and even allow multiple -u arguments. Yes, it is a simple matter to also allow:

    $ adduser -u sam -s -f -u bob -trace -verbose

    Get HTML5 localStorage keys

    If the browser supports HTML5 LocalStorage it should also implement, enabling this:

    Array.apply(0, new Array(localStorage.length)).map(function (o, i) {
        return localStorage.key(i);

    stop service in android

    This code works for me: check this link
    This is my code when i stop and start service in activity

      Log.d(TAG, "onClick: starting srvice");
      startService(new Intent(this, MyService.class));
      Log.d(TAG, "onClick: stopping srvice");
      stopService(new Intent(this, MyService.class));

    And in service class:

    public void onCreate() {
        Toast.makeText(this, "My Service Created", Toast.LENGTH_LONG).show();
        Log.d(TAG, "onCreate");
        player = MediaPlayer.create(this, R.raw.braincandy);
        player.setLooping(false); // Set looping
    public void onDestroy() {
        Toast.makeText(this, "My Service Stopped", Toast.LENGTH_LONG).show();
        Log.d(TAG, "onDestroy");


    How to join a slice of strings into a single string?

    Use a slice, not an arrray. Just create it using

    reg := []string {"a","b","c"}

    An alternative would have been to convert your array to a slice when joining :


    Read the Go blog about the differences between slices and arrays.

    Pull request vs Merge request

    In my point of view, they mean the same activity but from different perspectives:

    Think about that, Alice makes some commits on repository A, which was forked from Bob's repository B.

    When Alice wants to "merge" her changes into B, she actually wants Bob to "pull" these changes from A.

    Therefore, from Alice's point of view, it is a "merge request", while Bob views it as a "pull request".

    Java: How to Indent XML Generated by Transformer

    You need to enable 'INDENT' and set the indent amount for the transformer:

    t.setOutputProperty(OutputKeys.INDENT, "yes");
    t.setOutputProperty("{}indent-amount", "2");


    Reference : How to strip whitespace-only text nodes from a DOM before serialization?

    (Many thanks to all members especially @marc-novakowski, @james-murty and @saad):

    Android: Changing Background-Color of the Activity (Main View)

    Try creating a method in your Activity something like...

    public void setActivityBackgroundColor(int color) {
        View view = this.getWindow().getDecorView();

    Then call it from your OnClickListener passing in whatever colour you want.

    Laravel 5 - redirect to HTTPS

    for laravel 5.4 use this format to get https redirect instead of .htaccess

    namespace App\Providers;
    use Illuminate\Support\Facades\URL;
    use Illuminate\Support\ServiceProvider;
    class AppServiceProvider extends ServiceProvider
        public function boot()

    How to declare and add items to an array in Python?

    In some languages like JAVA you define an array using curly braces as following but in python it has a different meaning:


    int[] myIntArray = {1,2,3};
    String[] myStringArray = {"a","b","c"};

    However, in Python, curly braces are used to define dictionaries, which needs a key:value assignment as {'a':1, 'b':2}

    To actually define an array (which is actually called list in python) you can do:


    mylist = [1,2,3]

    or other examples like:

    mylist = list()
    >>> [1,2,3]

    Angular 4 Pipe Filter

    Here is a working plunkr with a filter and sortBy pipe.

    As developer033 mentioned in a comment, you are passing in a single value to the filter pipe, when the filter pipe is expecting an array of values. I would tell the pipe to expect a single value instead of an array

    export class FilterPipe implements PipeTransform {
        transform(items: any[], term: string): any {
            // I am unsure what id is here. did you mean title?
            return items.filter(item => !== -1);

    I would agree with DeborahK that impure pipes should be avoided for performance reasons. The plunkr includes console logs where you can see how much the impure pipe is called.