Programs & Examples On #Nemerle

Nemerle is a general-purpose, multi-paradigm programming language for the .Net platform.

Format an Integer using Java String Format

If you are using a third party library called apache commons-lang, the following solution can be useful:

Use StringUtils class of apache commons-lang :

int i = 5;
StringUtils.leftPad(String.valueOf(i), 3, "0"); // --> "005"

As StringUtils.leftPad() is faster than String.format()

Property 'map' does not exist on type 'Observable<Response>'

In rxjs 6 map operator usage has been changed now you need to Use it like this.

import { map } from 'rxjs/operators';
  .pipe(map(data => data * 2))

For reference

Could not create work tree dir ''.: Permission denied

Change ownership and permissions folder

sudo chown -R username.www-data /var/www

sudo chmod -R +rwx /var/www

Check if current date is between two dates Oracle SQL

TSQL: Dates- need to look for gaps in dates between Two Date

DATEDIFF(DAY,e1.enddate,e3.startdate)-1 as [Datediff]
from #temp e1 
   join #temp e3 on e1.enddate < e3.startdate          
       /* Finds the next start Time */
and e3.startdate = (select min(startdate) from #temp e5
where e5.startdate > e1.enddate)
and not exists (select *  /* Eliminates e1 rows if it is overlapped */
from #temp e5 
where e5.startdate < e1.enddate and e5.enddate > e1.enddate);

How do I check if an element is really visible with JavaScript?

As jkl pointed out, checking the element's visibility or display is not enough. You do have to check its ancestors. Selenium does this when it verifies visibility on an element.

Check out the method Selenium.prototype.isVisible in the selenium-api.js file.

Interface extends another interface but implements its methods

ad 1. It does not implement its methods.

ad 4. The purpose of one interface extending, not implementing another, is to build a more specific interface. For example, SortedMap is an interface that extends Map. A client not interested in the sorting aspect can code against Map and handle all the instances of for example TreeMap, which implements SortedMap. At the same time, another client interested in the sorted aspect can use those same instances through the SortedMap interface.

In your example you are repeating the methods from the superinterface. While legal, it's unnecessary and doesn't change anything in the end result. The compiled code will be exactly the same whether these methods are there or not. Whatever Eclipse's hover says is irrelevant to the basic truth that an interface does not implement anything.

Purpose of installing Twitter Bootstrap through npm?

Answer 1:

  • Downloading bootstrap through npm (or bower) permits you to gain some latency time. Instead of getting a remote resource, you get a local one, it's quicker, except if you use a cdn (check below answer)

  • "npm" was originally to get Node Module, but with the essort of the Javascript language (and the advent of browserify), it has a bit grown up. In fact, you can even download AngularJS on npm, that is not a server side framework. Browserify permits you to use AMD/RequireJS/CommonJS on client side so node modules can be used on client side.

Answer 2:

If you npm install bootstrap (if you dont use a particular grunt or gulp file to move to a dist folder), your bootstrap will be located in "./node_modules/bootstrap/bootstrap.min.css" if I m not wrong.

How do I POST urlencoded form data with $http without jQuery?

This worked for me. I use angular for front-end and laravel php for back-end. In my project, angular web sends json data to laravel back-end.

This is my angular controller.

var angularJsApp= angular.module('angularJsApp',[]);
angularJsApp.controller('MainCtrl', function ($scope ,$http) {

    $scope.userName ="Victoria";
    $scope.password ="password"

            method :'POST',
            data: { username :  $scope.userName , password: $scope.password},
            headers: {'Content-Type': 'application/json'}
        }).success(function (data, status, headers, config) {


This is my php back-end laravel controller.

public function httpTest(){
        if (Input::has('username')) {
            $user =Input::all();
            return  Response::json($user)->setCallback(Input::get('callback'));

This is my laravel routing


The result in browser is

status 200
data JSON_CALLBACK({"username":"Victoria","password":"password","callback":"JSON_CALLBACK"}); httpTesting.js:18 headers function (c){a||(a=sc(b));return c?a[K(c)]||null:a}

There is chrome extension called postman. You can use to test your back-end url whether it is working or not.

hopefully, my answer will help you.

Android - get children inside a View?

I'm just going to provide this answer as an alternative @IHeartAndroid's recursive algorithm for discovering all child Views in a view hierarchy. Note that at the time of this writing, the recursive solution is flawed in that it will contains duplicates in its result.

For those who have trouble wrapping their head around recursion, here's a non-recursive alternative. You get bonus points for realizing this is also a breadth-first search alternative to the depth-first approach of the recursive solution.

private List<View> getAllChildrenBFS(View v) {
    List<View> visited = new ArrayList<View>();
    List<View> unvisited = new ArrayList<View>();

    while (!unvisited.isEmpty()) {
        View child = unvisited.remove(0);
        if (!(child instanceof ViewGroup)) continue;
        ViewGroup group = (ViewGroup) child;
        final int childCount = group.getChildCount();
        for (int i=0; i<childCount; i++) unvisited.add(group.getChildAt(i));

    return visited;

A couple of quick tests (nothing formal) suggest this alternative is also faster, although that has most likely to do with the number of new ArrayList instances the other answer creates. Also, results may vary based on how vertical/horizontal the view hierarchy is.

Cross-posted from: Android | Get all children elements of a ViewGroup

Python dictionary get multiple values

If you have pandas installed you can turn it into a series with the keys as the index. So something like

import pandas as pd

s = pd.Series(my_dict)

s[['key1', 'key3', 'key2']]

header('HTTP/1.0 404 Not Found'); not doing anything

Use these codes for 404 not found.

  header('HTTP/1.0 404 Not Found');

Here 404missing.html is your Not found design page. (it can be .html or .php)

Angular: date filter adds timezone, how to output UTC?

I just used getLocaleString() function for my application. It should adapt the timeformat common to the locale, so no +0200 etc. Ofcourse, there will be less possibility for controlling the width of your string then.

var str = (new Date(1400167800)).toLocaleString();

Dynamically Dimensioning A VBA Array?

You have to use the ReDim statement to dynamically size arrays.

Public Sub Test()
    Dim NumberOfZombies As Integer
    NumberOfZombies = 20000
    Dim Zombies() As New Zombie
    ReDim Zombies(NumberOfZombies)

End Sub

This can seem strange when you already know the size of your array, but there you go!

Generate HTML table from 2D JavaScript array

See the fiddle demo to create a table from an array.

function createTable(tableData) {
  var table = document.createElement('table');
  var row = {};
  var cell = {};

  tableData.forEach(function(rowData) {
    row = table.insertRow(-1); // [-1] for last position in Safari
    rowData.forEach(function(cellData) {
      cell = row.insertCell();
      cell.textContent = cellData;

You can use it like this

var tableData = [["r1c1", "r1c2"], ["r2c1", "r2c2"], ["r3c1", "r3c2"]];

Android statusbar icons color

Setting windowLightStatusBar to true not works with Mi phones, some Meizu phones, Blackview phones, WileyFox etc. I've found such hack for Mi and Meizu devices. This is not a comprehensive solution of this perfomance problem, but maybe it would be useful to somebody.

And I think, it would be better to tell your customer that coloring status bar (for example) white - is not a good idea. instead of using different hacks it would be better to define appropriate colorPrimaryDark according to the guidelines

MySQL Workbench: "Can't connect to MySQL server on' (10061)" error

Even I had same problem, The reason was mysql service was not getting configured properly, when I installed it through 'MySQL installer'. Also it was not starting, when I tried to start the service manually.

So in my case it seemed be a Bug with the 'MySQL Installer', as editing the install path to a different one when the 'Developer default' was selected, the problem occurs.

Solution (Not exactly a solution):

  • Uninstalled the MySQL all products (completely)
  • Reinstalled, this time also I have selected 'Developer default', but didn't make any changes to the path or any thing. So the path was just 'C:\Program Files\MySQL' (the default one)
  • And just clicked Next Next...
  • Done, this time MySql was running fine.

Casting a variable using a Type variable

After not finding anything to get around "Object must implement IConvertible" exception when using Zyphrax's answer (except for implementing the interface).. I tried something a little bit unconventional and worked for my situation.

Using the Newtonsoft.Json nuget package...

var castedObject = JsonConvert.DeserializeObject(JsonConvert.SerializeObject(myObject), myType);

How to make a countdown timer in Android?

enter image description here

package com.zeustechnocrats.countdown;

import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TextView;

import java.text.SimpleDateFormat;
import java.util.Date;

public class MainActivity extends AppCompatActivity {

    private String EVENT_DATE_TIME = "2020-12-31 10:30:00";
    private String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss";
    private LinearLayout linear_layout_1, linear_layout_2;
    private TextView tv_days, tv_hour, tv_minute, tv_second;
    private Handler handler = new Handler();
    private Runnable runnable;

    protected void onCreate(Bundle savedInstanceState) {


    private void initUI() {
        linear_layout_1 = findViewById(;
        linear_layout_2 = findViewById(;
        tv_days = findViewById(;
        tv_hour = findViewById(;
        tv_minute = findViewById(;
        tv_second = findViewById(;

    private void countDownStart() {
        runnable = new Runnable() {
            public void run() {
                try {
                    handler.postDelayed(this, 1000);
                    SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);
                    Date event_date = dateFormat.parse(EVENT_DATE_TIME);
                    Date current_date = new Date();
                    if (!current_date.after(event_date)) {
                        long diff = event_date.getTime() - current_date.getTime();
                        long Days = diff / (24 * 60 * 60 * 1000);
                        long Hours = diff / (60 * 60 * 1000) % 24;
                        long Minutes = diff / (60 * 1000) % 60;
                        long Seconds = diff / 1000 % 60;
                        tv_days.setText(String.format("%02d", Days));
                        tv_hour.setText(String.format("%02d", Hours));
                        tv_minute.setText(String.format("%02d", Minutes));
                        tv_second.setText(String.format("%02d", Seconds));
                    } else {
                } catch (Exception e) {
        handler.postDelayed(runnable, 0);

    protected void onStop() {


    <LinearLayout xmlns:android=""


            android:text="Android Event Start"
            android:textStyle="normal" />



                android:textStyle="bold" />

                android:textStyle="normal" />


                android:textStyle="bold" />

                android:textStyle="normal" />


                android:textStyle="bold" />

                android:textStyle="normal" />


                android:textStyle="bold" />

                android:textStyle="normal" />

Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) for operation '='

In my own case I have the following error

Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation '='

$this->db->select("users.username as matric_no, CONCAT(users.surname, ' ', users.first_name, ' ', users.last_name) as fullname") ->join('users', 'users.username=classroom_students.matric_no', 'left') ->where('classroom_students.session_id', $session) ->where('classroom_students.level_id', $level) ->where('classroom_students.dept_id', $dept);

After weeks of google searching I noticed that the two fields I am comparing consists of different collation name. The first one i.e username is of utf8_general_ci while the second one is of utf8_unicode_ci so I went back to the structure of the second table and changed the second field (matric_no) to utf8_general_ci and it worked like a charm.

JetBrains / IntelliJ keyboard shortcut to collapse all methods

go to menu option Code > Folding to access all code folding related options and their shortcuts.

SQL: how to select a single id ("row") that meets multiple criteria from a single column

one of the approach if you want to get all user_id that satisfies all conditions is:

SELECT DISTINCT user_id FROM table WHERE ancestry IN ('England', '...', '...') GROUP BY user_id HAVING count(*) = <number of conditions that has to be satisfied> 

etc. If you need to take all user_ids that satisfies at least one condition, then you can do

SELECT DISTINCT user_id from table where ancestry IN ('England', 'France', ... , '...')

I am not aware if there is something similar to IN but that joins conditions with AND instead of OR

Current timestamp as filename in Java

No need to get too complicated, try this one liner:

String fileName = new SimpleDateFormat("yyyyMMddHHmm'.txt'").format(new Date());

Running Internet Explorer 6, Internet Explorer 7, and Internet Explorer 8 on the same machine

I've installed Virutal PC according to Donavon's tutorial but it seems that my laptop's BIOS doesn't support Hardware Virtualization, and it's required to run Virtual PC. So, make sure your equipment supports that before you go any further wirh Virtual PC.

ImportError: No module named pythoncom

If you're on windows you probably want the pywin32 library, which includes pythoncom and a whole lot of other stuff that is pretty standard.

[Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified

The Problem might be from the driver name for example instead of DRIVER={MySQL ODBC 5.3 Driver} try DRIVER={MySQL ODBC 5.3 Unicode Driver} you can see the name of the driver from administration tool

C#: calling a button event handler method without actually clicking the button

You have to pass parameter sender and e to call button event handler in .cs file


Getting started with Haskell

Some colleague of mine had good experience with Learn You a Haskell for Great Good!.

Tutorial aimed at people who have experience in imperative programming languages but haven't programmed in a functional language before.

And check the answers here too

Insert variable into Header Location PHP

Try using double quotes and keeping the L in location lowercase...


or for example


No need to concatenate here to insert variables.

How to play YouTube video in my Android application?

This is the btn click event

btnvideo.setOnClickListener(new OnClickListener() {

public void onClick(View v) {

    startActivity(new Intent(Intent.ACTION_VIEW,Uri.parse("")));
    Log.i("Video", "Video Playing....");


this type it opened in another page with the youtube where u can show your video

View list of all JavaScript variables in Google Chrome Console

Open the console and then enter:

  • keys(window) to see variables
  • dir(window) to see objects

What is the different between RESTful and RESTless

Any model which don't identify resource and the action associated with is restless. restless is not any term but a slang term to represent all other services that doesn't abide with the above definition. In restful model resource is identified by URL (NOUN) and the actions(VERBS) by the predefined methods in HTTP protocols i.e. GET, POST, PUT, DELETE etc.

#1273 – Unknown collation: ‘utf8mb4_unicode_520_ci’

In my case I substitute it with utf8_general_ci with sed like this:

sed -i 's/utf8_0900_ai_ci/utf8_general_ci/g' MY_DB.sql 
sed -i 's/utf8mb4_unicode_520_ci/utf8_general_ci/g' MY_DB.sql 

After that, I can import it without any issue.

onclick on a image to navigate to another page using Javascript

I'd set up your HTML like so:

<img src="../images/bottle.jpg" alt="bottle" class="thumbnails" id="bottle" />

Then use the following code:

var images = document.getElementsByTagName("img");
for(var i = 0; i < images.length; i++) {
    var image = images[i];
    image.onclick = function(event) {
         window.location.href = + '.html';

That assigns an onclick event handler to every image on the page (this may not be what you want, you can limit it further if necessary) that changes the current page to the value of the images id attribute plus the .html extension. It's essentially the pure Javascript implementation of @JanPöschko's jQuery answer.

How do I use two submit buttons, and differentiate between which one was used to submit the form?

Give each input a name attribute. Only the clicked input's name attribute will be sent to the server.

<input type="submit" name="publish" value="Publish">
<input type="submit" name="save" value="Save">

And then

    if (isset($_POST['publish'])) {
        # Publish-button was clicked
    elseif (isset($_POST['save'])) {
        # Save-button was clicked

Edit: Changed value attributes to alt. Not sure this is the best approach for image buttons though, any particular reason you don't want to use input[type=image]?

Edit: Since this keeps getting upvotes I went ahead and changed the weird alt/value code to real submit inputs. I believe the original question asked for some sort of image buttons but there are so much better ways to achieve that nowadays instead of using input[type=image].

React.createElement: type is invalid -- expected a string

I got the exactly same error, Do this instead:

npm install react-router@next 
npm install --save history

Why is my power operator (^) not working?

First of all ^ is a Bitwise XOR operator not power operator.

You can use other things to find power of any number. You can use for loop to find power of any number

Here is a program to find x^y i.e. xy

double i, x, y, pow;

x = 2;
y = 5; 
pow = 1;
for(i=1; i<=y; i++)
    pow = pow * x;

printf("2^5 = %lf", pow);

You can also simply use pow() function to find power of any number

double power, x, y;
x = 2;
y = 5;
power = pow(x, y); /* include math.h header file */

printf("2^5 = %lf", power);

How do I parse a YAML file in Ruby?

Here is the one liner i use, from terminal, to test the content of yml file(s):

$ ruby  -r yaml -r pp  -e 'pp YAML.load_file("/Users/za/project/application.yml")'
    {"root"=>"WARN", "org"=>{"springframework"=>{"security"=>"DEBUG"}}}}}

How to get the current time in YYYY-MM-DD HH:MI:Sec.Millisecond format in Java?

The doc in Java 8 names it fraction-of-second , while in Java 6 was named millisecond. This brought me to confusion

Angular JS: What is the need of the directive’s link function when we already had directive’s controller with scope?

The controller function/object represents an abstraction model-view-controller (MVC). While there is nothing new to write about MVC, it is still the most significant advanatage of angular: split the concerns into smaller pieces. And that's it, nothing more, so if you need to react on Model changes coming from View the Controller is the right person to do that job.

The story about link function is different, it is coming from different perspective then MVC. And is really essential, once we want to cross the boundaries of a controller/model/view (template).

Let' start with the parameters which are passed into the link function:

function link(scope, element, attrs) {
  • scope is an Angular scope object.
  • element is the jqLite-wrapped element that this directive matches.
  • attrs is an object with the normalized attribute names and their corresponding values.

To put the link into the context, we should mention that all directives are going through this initialization process steps: Compile, Link. An Extract from Brad Green and Shyam Seshadri book Angular JS:

Compile phase (a sister of link, let's mention it here to get a clear picture):

In this phase, Angular walks the DOM to identify all the registered directives in the template. For each directive, it then transforms the DOM based on the directive’s rules (template, replace, transclude, and so on), and calls the compile function if it exists. The result is a compiled template function,

Link phase:

To make the view dynamic, Angular then runs a link function for each directive. The link functions typically creates listeners on the DOM or the model. These listeners keep the view and the model in sync at all times.

A nice example how to use the link could be found here: Creating Custom Directives. See the example: Creating a Directive that Manipulates the DOM, which inserts a "date-time" into page, refreshed every second.

Just a very short snippet from that rich source above, showing the real manipulation with DOM. There is hooked function to $timeout service, and also it is cleared in its destructor call to avoid memory leaks

.directive('myCurrentTime', function($timeout, dateFilter) {

 function link(scope, element, attrs) {


 // the not MVC job must be done
 function updateTime() {
   element.text(dateFilter(new Date(), format)); // here we are manipulating the DOM

 function scheduleUpdate() {
   // save the timeoutId for canceling
   timeoutId = $timeout(function() {
     updateTime(); // update DOM
     scheduleUpdate(); // schedule the next update
   }, 1000);

 element.on('$destroy', function() {


Sorting string array in C#

This code snippet is working properly enter image description here

PHP array() to javascript array()

 <script> var disabledDaysRange = $disabledDaysRange ???? Please Help;
 $(function() {
     function disableRangeOfDays(d) {

in the above assign array to javascript variable "disableDaysRange"

$disallowDates = "";
echo "[";
foreach($disabledDaysRange as $disableDates){
 $disallowDates .= "'".$disableDates."',";

echo substr(disallowDates,0,(strlen(disallowDates)-1)); // this will escape the last comma from $disallowDates
echo "];";

so your javascript var diableDateRange shoudl be 

var diableDateRange = ["2013-01-01","2013-01-02","2013-01-03"];

Stream file using ASP.NET MVC FileContentResult in a browser with a name?

Actually, the absolutely easiest way is to do the following...

byte[] content = your_byte[];

FileContentResult result = new FileContentResult(content, "application/octet-stream") 
  FileDownloadName = "your_file_name"

return result;

How do I get the position selected in a RecyclerView?

A different method - using setTag() and getTag() methods of the View class.

  1. use setTag() in the onBindViewHolder method of your adapter

    public void onBindViewHolder(myViewHolder viewHolder, int position) {

    where mCardView is defined in the myViewHolder class

    private class myViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
               public View mCardView;
               public myViewHolder(View view) {
                   mCardView = (CardView) view.findViewById(;
  2. use getTag() in your OnClickListener implementation

    public void onClick(View view) {
        int position = (int) view.getTag();           
    //display toast with position of cardview in recyclerview list upon click

see for more details

How to set ChartJS Y axis title?

For x and y axes:

     options : {
      scales: {
        yAxes: [{
          scaleLabel: {
            display: true,
            labelString: 'probability'
        xAxes: [{
          scaleLabel: {
            display: true,
            labelString: 'hola'

T-SQL: Selecting rows to delete via joins

The simpler way is:

WHERE TableA.ID = TableB.ID

Where to get this Java.exe file for a SQL Developer installation

I encountered the following message repeatedly when trying to start SQL Developer from my installation of Oracle Database 11g Enterprise: Enter the full pathname for java.exe.

No matter how many times I browsed to the correct path, I kept being presented with the exact same dialog box. This was in Windows 7, and the solution was to right-click on the SQL Developer icon and select "Run as administrator". I then used this path: C:\app\shellperson\product\11.1.0\db_1\jdk\jre\bin\java.exe

What is the easiest way to get the current day of the week in Android?

public String weekdays[] = new      DateFormatSymbols(Locale.ITALIAN).getWeekdays();
 Calendar c = Calendar.getInstance();
 Date date = new Date();
 int dayOfWeek = c.get(Calendar.DAY_OF_WEEK);

Cannot open include file: 'stdio.h' - Visual Studio Community 2017 - C++ Error

Just in case you don't want to bump Windows SDK to Windows 10 (you could be for example working on an open source project where the decision isn't yours to make), you can solve this problem in a Windows SDK 8.1 project by navigating Tools -> Get Tools and Features... -> Individual Compontents tab and installing the individual components "Windows 8.1 SDK" (under SDKs, libraries and frameworks) and "Windows Universal CRT SDK" (under Compilers, build tools and runtimes):

PHP header redirect 301 - what are the implications?

Make sure you die() after your redirection, and make sure you do your redirect AS SOON AS POSSIBLE while your script executes. It makes sure that no more database queries (if some) are not wasted for nothing. That's the one tip I can give you

For search engines, 301 is the best response code

Running npm command within Visual Studio Code

There might be a chance that you have install node.js while your visual studio code was open. Once node.js is install successfully, Simply close the VS Code and Start it again. It will work. Thank you

Jenkins returned status code 128 with github

When I got a similar status code 128 error from Jenkins:

status code 128:
stderr: fatal: Couldn't find remote ref refs/heads/jenkins

    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(
    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandWithCredentials(
    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.access$500(
    at org.jenkinsci.plugins.gitclient.CliGitAPIImpl$1.execute(
    at jenkins.plugins.git.GitSCMFileSystem$
    at jenkins.scm.api.SCMFileSystem.of(
    at jenkins.scm.api.SCMFileSystem.of(
    at org.jenkinsci.plugins.workflow.cps.CpsScmFlowDefinition.create(
    at org.jenkinsci.plugins.workflow.cps.CpsScmFlowDefinition.create(
    at hudson.model.ResourceController.execute(
Finished: FAILURE

It was because I hadn't pushed my new branch "jenkins" that had my Jenkinsfile. So the solution was to just push my changes

Is there any way to wait for AJAX response and halt execution?

When using promises they can be used in a promise chain. async=false will be deprecated so using promises is your best option.

function functABC() {
  return new Promise(function(resolve, reject) {
      url: 'myPage.php',
      data: {id: id},
      success: function(data) {
        resolve(data) // Resolve promise and go to then()
      error: function(err) {
        reject(err) // Reject the promise and go to catch()

functABC().then(function(data) {
  // Run this when your request was successful
}).catch(function(err) {
  // Run this when promise was rejected via reject()

Amazon S3 exception: "The specified key does not exist"

Well this error is actually rather straight forward.  it simply means that your file does not exist up within the S3 bucket.  Several things could be wrong:

  1. You could be trying to reference the wrong file.  Double check the path that you tried to retrieve.

  2. Whenever the file was uploaded it must have failed.  Check the logs for your S3Sync process to see if you can find any relevant output


How to find the length of an array in shell?

From Bash manual:


The length in characters of the expanded value of parameter is substituted. If parameter is ‘’ or ‘@’, the value substituted is the number of positional parameters. If parameter is an array name subscripted by ‘’ or ‘@’, the value substituted is the number of elements in the array. If parameter is an indexed array name subscripted by a negative number, that number is interpreted as relative to one greater than the maximum index of parameter, so negative indices count back from the end of the array, and an index of -1 references the last element.

Length of strings, arrays, and associative arrays

string="0123456789"                   # create a string of 10 characters
array=(0 1 2 3 4 5 6 7 8 9)           # create an indexed array of 10 elements
declare -A hash
hash=([one]=1 [two]=2 [three]=3)      # create an associative array of 3 elements
echo "string length is: ${#string}"   # length of string
echo "array length is: ${#array[@]}"  # length of array using @ as the index
echo "array length is: ${#array[*]}"  # length of array using * as the index
echo "hash length is: ${#hash[@]}"    # length of array using @ as the index
echo "hash length is: ${#hash[*]}"    # length of array using * as the index


string length is: 10
array length is: 10
array length is: 10
hash length is: 3
hash length is: 3

Dealing with $@, the argument array:

set arg1 arg2 "arg 3"
echo "number of args is: $#"
echo "number of args is: ${#@}"
echo "args_copy length is: ${#args_copy[@]}"


number of args is: 3
number of args is: 3
args_copy length is: 3

Vim and Ctags tips and tricks

You can add directories to your ctags lookup. For example, I have a ctags index built for Qt4, and have this in my .vimrc:

set tags+=/usr/local/share/ctags/qt4

How to hide html source & disable right click and text copy?

The following website has both right click and view source disabled.

They fooled you. Just scroll down in view-source.

Furthermore, employing such tactics marks you as unprofessional. Don’t do it.

How to call function of one php file from another php file and pass parameters to it?

you can write the function in a separate file (say common-functions.php) and include it wherever needed.

function getEmployeeFullName($employeeId) {
// Write code to return full name based on $employeeId

You can include common-functions.php in another file as below.

echo 'Name of first employee is ' . getEmployeeFullName(1);

You can include any number of files to another file. But including comes with a little performance cost. Therefore include only the files which are really required.

Java List.add() UnsupportedOperationException

instead of using add() we can use addall()

{ seeAlso.addall(groupDn); }

add adds a single item, while addAll adds each item from the collection one by one. In the end, both methods return true if the collection has been modified. In case of ArrayList this is trivial, because the collection is always modified, but other collections, such as Set, may return false if items being added are already there.

ImportError: no module named win32api

According to pywin32 github you must run

    pip install pywin32

and after that, you must run

    python Scripts/ -install

I know I'm reviving an old thread, but I just had this problem and this was the only way to solve it.

How can I give an imageview click effect like a button on Android?

As for now, we should develop Material Design practice. In this case you could add a ripple effect on an ImageView.

Changing column names of a data frame

This may be helpful:

  #renames columns of a dataframe
  for(i in 1:length(names(df))){
      names(df)[i]= changelist[[names(df)[i]]]

# Specify new dataframe

How to strip HTML tags from a string in SQL Server?

Try this. It's a modified version of the one posted by RedFilter ... this SQL removes all tags except BR, B, and P with any accompanying attributes:

 DECLARE @TempStr varchar(255)

 SET @Start = CHARINDEX('<',@HTMLText)
 SET @Length = (@End - @Start) + 1

 WHILE @Start > 0 AND @End > 0 AND @Length > 0
   IF (UPPER(SUBSTRING(@HTMLText, @Start, 3)) <> '<BR') AND (UPPER(SUBSTRING(@HTMLText, @Start, 2)) <> '<P') AND (UPPER(SUBSTRING(@HTMLText, @Start, 2)) <> '<B') AND (UPPER(SUBSTRING(@HTMLText, @Start, 3)) <> '</B')
      SET @HTMLText = STUFF(@HTMLText,@Start,@Length,'')
   SET @Start = CHARINDEX('<',@HTMLText, @End)
   SET @End = CHARINDEX('>',@HTMLText,CHARINDEX('<',@HTMLText, @Start))
   SET @Length = (@End - @Start) - 1


What is the difference between MacVim and regular Vim?

unfortunately, with "mvim -v", ALT plus arrow windows still does not work. I have not found any way to enable it :-(

How to randomly select rows in SQL?

There is a nice Microsoft SQL Server 2005 specific solution here. Deals with the problem where you are working with a large result set (not the question I know).

Selecting Rows Randomly from a Large Table

jQuery animate margin top

MarginTop should be marginTop.

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]);


Getting ORA-01031: insufficient privileges while querying a table instead of ORA-00942: table or view does not exist

ORA-01031: insufficient privileges Solution: Go to Your System User. then Write This Code:

SQL> grant dba to UserName; //Put This username which user show this error message.

Grant succeeded.

Why do I have to "git push --set-upstream origin <branch>"?

My understanding is that "-u" or "--set-upstream" allows you to specify the upstream (remote) repository for the branch you're on, so that next time you run "git push", you don't even have to specify the remote repository.

Push and set upstream (remote) repository as origin:

$ git push -u origin

Next time you push, you don't have to specify the remote repository:

$ git push

How to convert ZonedDateTime to Date?

For a docker application like beehuang commented you should set your timezone.

Alternatively you can use withZoneSameLocal. For example:

2014-07-01T00:00+02:00[GMT+02:00] is converted by


to Tue Jul 01 00:00:00 CEST 2014 and by


to Mon Jun 30 22:00:00 UTC 2014

How to download image using requests

This is the first response that comes up for google searches on how to download a binary file with requests. In case you need to download an arbitrary file with requests, you can use:

import requests
url = ''
open('GoogleNews-vectors-negative300.bin.gz', 'wb').write(requests.get(url, allow_redirects=True).content)

Programmatically check Play Store for app updates

confirmed only that method work now:

newVersion = Jsoup.connect("" + AcMainPage.this.getPackageName() + "&hl=it")
                        .userAgent("Mozilla/5.0 (Windows; U; WindowsNT 5.1; en-US; rv1.8.1.6) Gecko/20070725 Firefox/")
                        .select(".hAyfc .htlgb")

What does -save-dev mean in npm install grunt --save-dev

--save-dev: Package will appear in your devDependencies.

According to the npm install docs.

If someone is planning on downloading and using your module in their program, then they probably don't want or need to download and build the external test or documentation framework that you use.

In other words, when you run npm install, your project's devDependencies will be installed, but the devDependencies for any packages that your app depends on will not be installed; further, other apps having your app as a dependency need not install your devDependencies. Such modules should only be needed when developing the app (eg grunt, mocha etc).

According to the package.json docs

Edit: Attempt at visualising what npm install does:

  • yourproject
    • dependency installed
      • dependency installed
        • dependency installed
        • devDependency NOT installed
      • devDependency NOT installed
    • devDependency installed
      • dependency installed
      • devDependency NOT installed

Access properties file programmatically with Spring?

This post also explatis howto access properties:

You can access properties loaded by spring property-placeholder over such spring bean:

public class PropertiesAccessor {

    private final AbstractBeanFactory beanFactory;

    private final Map<String,String> cache = new ConcurrentHashMap<>();

    protected PropertiesAccessor(AbstractBeanFactory beanFactory) {
        this.beanFactory = beanFactory;

    public  String getProperty(String key) {
            return cache.get(key);

        String foundProp = null;
        try {
            foundProp = beanFactory.resolveEmbeddedValue("${" + key.trim() + "}");
        } catch (IllegalArgumentException ex) {
           // ok - property was not found

        return foundProp;

using jquery $.ajax to call a PHP function

Use $.ajax to call a server context (or URL, or whatever) to invoke a particular 'action'. What you want is something like:

$.ajax({ url: '/my/site',
         data: {action: 'test'},
         type: 'post',
         success: function(output) {

On the server side, the action POST parameter should be read and the corresponding value should point to the method to invoke, e.g.:

if(isset($_POST['action']) && !empty($_POST['action'])) {
    $action = $_POST['action'];
    switch($action) {
        case 'test' : test();break;
        case 'blah' : blah();break;
        // ...etc...

I believe that's a simple incarnation of the Command pattern.

Install IPA with iTunes 11

In iTunes 11 you can go to the view menu, and "Show Sidebar", this will give you the sidebar, that you can drag 'n drop to.

You'll drag 'n drop to the open area that will be near the bottom of the sidebar (I'm typically doing this with both an IPA and a provisioning profile). After you do that, there will be an apps menu that appears in the sidebar with your app in it. Click on that, and you'll see your application in the main view. You can then drag your application from there to your device. Below, please find a video (it's private, so you'll need the URL) that outlines the steps visually:

How to replace a character by a newline in Vim

Here's the trick:

First, set your Vi(m) session to allow pattern matching with special characters (i.e.: newline). It's probably worth putting this line in your .vimrc or .exrc file:

:set magic

Next, do:


To get the ^M character, type Ctrl + V and hit Enter. Under Windows, do Ctrl + Q, Enter. The only way I can remember these is by remembering how little sense they make:

A: What would be the worst control-character to use to represent a newline?

B: Either q (because it usually means "Quit") or v because it would be so easy to type Ctrl + C by mistake and kill the editor.

A: Make it so.

CSS selectors ul li a {...} vs ul > li > a {...}

1) for example HTML code:

        <a href="#">firstlink</a>
        <span><a href="#">second link&lt;/a>

and css rules:

1) ul li a {color:red;} 
2) ul > li > a {color:blue;}

">" - symbol mean that that will be searching only child selector (parentTag > childTag)

so first css rule will apply to all links (first and second) and second rule will apply anly to first link

2) As for efficiency - I think second will be more fast - as in case with JavaScript selectors. This rule read from right to left, this mean that when rule will parse by browser, it get all links on page: - in first case it will find all parent elements for each link on page and filter all links where exist parent tags "ul" and "li" - in second case it will check only parent node of link if it is "li" tag then -> check if parent tag of "li" is "ul"

some thing like this. Hope I describe all properly for you

Get selected option text with JavaScript

There are two solutions, as far as I know.

both that just need using vanilla javascript

1 selectedOptions

live demo

const log = console.log;_x000D_
const areaSelect = document.querySelector(`[id="area"]`);_x000D_
areaSelect.addEventListener(`change`, (e) => {_x000D_
  // log(``,;_x000D_
  const select =;_x000D_
  const value = select.value;_x000D_
  const desc = select.selectedOptions[0].text;_x000D_
  log(`option desc`, desc);_x000D_
<div class="select-box clearfix">_x000D_
  <label for="area">Area</label>_x000D_
  <select id="area">_x000D_
    <option value="101">A1</option>_x000D_
    <option value="102">B2</option>_x000D_
    <option value="103">C3</option>_x000D_

2 options

live demo

const log = console.log;_x000D_
const areaSelect = document.querySelector(`[id="area"]`);_x000D_
areaSelect.addEventListener(`change`, (e) => {_x000D_
  // log(``,;_x000D_
  const select =;_x000D_
  const value = select.value;_x000D_
  const desc = select.options[select.selectedIndex].text;_x000D_
  log(`option desc`, desc);_x000D_
<div class="select-box clearfix">_x000D_
  <label for="area">Area</label>_x000D_
  <select id="area">_x000D_
    <option value="101">A1</option>_x000D_
    <option value="102">B2</option>_x000D_
    <option value="103">C3</option>_x000D_

Apache default VirtualHost

I will say what worked for me, the others answers above didn't help to my case at all. I hope it can help someone.

Actually, I'm using Virtual host configuration (sites-available / sites-enabled) on EC2 Linux AMI with Apache/2.4.39 (Amazon). So, I have 1 ec2 instance to serve many sites (domains).

Considering that you already have Virtual Host installed and working. In my folder /etc/httpd/sites-available, I have some files with domain names (suffix .conf), for example: Create a new file like that.

sudo nano /etc/httpd/sites-available/

<VirtualHost *:80>
    DocumentRoot /var/www/html/domain

For each file.conf in sites-available, I create a symbolic link:

sudo ln -s /etc/httpd/sites-available/ /etc/httpd/sites-enabled/

This is the default configuration, so, if access directly by IP of Server, you will be redirect to DocumentRoot of the first file (.conf) in sites-available folder, sorted by filename.

To have a default DocumentRoot folder when access by IP, you have to create a file named 0a.conf, then apache will serve this site because this new file will be the first in sites-available folder.

You must create a symbolic link:

sudo ln -s /etc/httpd/sites-available/0a.conf /etc/httpd/sites-enabled/0a.conf

To check serving order, use it:

sudo apachectl -S

Now, restart apache, and check out it.

Be happy =)

How can I get all element values from Request.Form without specifying exactly which one with .GetValues("ElementIdName")

Here is a way to do it without adding an ID to the form elements.

<form method="post">
    <select name="List">
        <option value="1">Test1</option>
        <option value="2">Test2</option>
    <select name="List">
        <option value="3">Test3</option>
        <option value="4">Test4</option>

public ActionResult OrderProcessor()
    string[] ids = Request.Form.GetValues("List");

Then ids will contain all the selected option values from the select lists. Also, you could go down the Model Binder route like so:

public class OrderModel
    public string[] List { get; set; }

public ActionResult OrderProcessor(OrderModel model)
    string[] ids = model.List;

Hope this helps.

Loading state button in Bootstrap 3

You need to detect the click from js side, your HTML remaining same. Note: this method is deprecated since v3.5.5 and removed in v4.

$("button").click(function() {
    var $btn = $(this);
    // simulating a timeout
    setTimeout(function () {
    }, 1000);

Also, don't forget to load jQuery and Bootstrap js (based on jQuery) file in your page.


Official Documentation

Firebase onMessageReceived not called when app in background

This is working as intended, notification messages are delivered to your onMessageReceived callback only when your app is in the foreground. If your app is in the background or closed then a notification message is shown in the notification center, and any data from that message is passed to the intent that is launched as a result of the user tapping on the notification.

You can specify a click_action to indicate the intent that should be launched when the notification is tapped by the user. The main activity is used if no click_action is specified.

When the intent is launched you can use the


to retrieve a Set that would include any data sent along with the notification message.

For more on notification message see docs.

postgreSQL - psql \i : how to execute script in a given path

i did try this and its working in windows machine to run a sql file on a specific schema.

psql -h localhost -p 5432 -U username -d databasename -v schema=schemaname < e:\Table.sql

Simple URL GET/POST function in Python

import urllib

def fetch_thing(url, params, method):
    params = urllib.urlencode(params)
    if method=='POST':
        f = urllib.urlopen(url, params)
        f = urllib.urlopen(url+'?'+params)
    return (, f.code)

content, response_code = fetch_thing(
                              {'spam': 1, 'eggs': 2, 'bacon': 0}, 


Some of these answers are old. Today I would use the requests module like the answer by robaple.

Matplotlib discrete colorbar

To set a values above or below the range of the colormap, you'll want to use the set_over and set_under methods of the colormap. If you want to flag a particular value, mask it (i.e. create a masked array), and use the set_bad method. (Have a look at the documentation for the base colormap class: )

It sounds like you want something like this:

import matplotlib.pyplot as plt
import numpy as np

# Generate some data
x, y, z = np.random.random((3, 30))
z = z * 20 + 0.1

# Set some values in z to 0...
z[:5] = 0

cmap = plt.get_cmap('jet', 20)

fig, ax = plt.subplots()
cax = ax.scatter(x, y, c=z, s=100, cmap=cmap, vmin=0.1, vmax=z.max())
fig.colorbar(cax, extend='min')

enter image description here

ios simulator: how to close an app

Command + shift +h Press H 2 times

Note :- Press H 2 times

A message body writer for Java type, class myPackage.B, and MIME media type, application/octet-stream, was not found

Adding reference to:


As long as adding clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, true); on client creation solved the issue for me:

ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, true);
Client client = Client.create(clientConfig);

Get an image extension from an uploaded file in Laravel

Do something like this:


    $path = Storage::putFileAs(
            '/', $video, $filename

Hide options in a select list using jQuery


Then, in your css make sure you have


Insert if not exists Oracle

   tmp NUMBER(3,1);
  SELECT COUNT(content_id) INTO tmp FROM contents WHERE (condition);
  if tmp != 0 then
    INSERT INTO contents VALUES (...);
    INSERT INTO contents VALUES (...);
  end if;

I used the code above. It is long, but, simple and worked for me. Similar, to Micheal's code.

Named parameters in JDBC

Vanilla JDBC only supports named parameters in a CallableStatement (e.g. setString("name", name)), and even then, I suspect the underlying stored procedure implementation has to support it.

An example of how to use named parameters:

//uss Sybase ASE sysobjects table...adjust for your RDBMS
stmt = conn.prepareCall("create procedure p1 (@id int = null, @name varchar(255) = null) as begin "
        + "if @id is not null "
        + "select * from sysobjects where id = @id "
        + "else if @name is not null "
        + "select * from sysobjects where name = @name "
        + " end");

//call the proc using one of the 2 optional params
stmt = conn.prepareCall("{call p1 ?}");
stmt.setInt("@id", 10);
ResultSet rs = stmt.executeQuery();
while (

//use the other optional param
stmt = conn.prepareCall("{call p1 ?}");
stmt.setString("@name", "sysprocedures");
rs = stmt.executeQuery();
while (

How to copy only a single worksheet to another workbook using vba

The much longer example below combines some of the useful snippets above:

  • You can specify any number of sheets you want to copy across
  • You can copy entire sheets, i.e. like dragging the tab across, or you can copy over the contents of cells as values-only but preserving formatting.

It could still do with a lot of work to make it better (better error-handling, general cleaning up), but it hopefully provides a good start.

Note that not all formatting is carried across because the new sheet uses its own theme's fonts and colours. I can't work out how to copy those across when pasting as values only.

 Option Explicit

Sub copyDataToNewFile()
    Application.ScreenUpdating = False

    ' Allow different ways of copying data:
    ' sheet = copy the entire sheet
    ' valuesWithFormatting = create a new sheet with the same name as the
    '                        original, copy values from the cells only, then
    '                        apply original formatting. Formatting is only as
    '                        good as the Paste Special > Formats command - theme
    '                        colours and fonts are not preserved.
    Dim copyMethod As String
    copyMethod = "valuesWithFormatting"

    Dim newFilename As String           ' Name (+optionally path) of new file
    Dim themeTempFilePath As String     ' To temporarily save the source file's theme

    Dim sourceWorkbook As Workbook      ' This file
    Set sourceWorkbook = ThisWorkbook

    Dim newWorkbook As Workbook         ' New file

    Dim sht As Worksheet                ' To iterate through sheets later on.
    Dim sheetFriendlyName As String     ' To store friendly sheet name
    Dim sheetCount As Long              ' To avoid having to count multiple times

    ' Sheets to copy over, using internal code names as more reliable.
    Dim colSheetObjectsToCopy As New Collection
    colSheetObjectsToCopy.Add Sheet1
    colSheetObjectsToCopy.Add Sheet2

    ' Get filename of new file from user.
        newFilename = InputBox("Please Specify the name of your new workbook." & vbCr & vbCr & "Either enter a full path or just a filename, in which case the file will be saved in the same location (" & sourceWorkbook.Path & "). Don't use the name of a workbook that is already open, otherwise this script will break.", "New Copy")
        If newFilename = "" Then MsgBox "You must enter something.", vbExclamation, "Filename needed"
    Loop Until newFilename > ""

    ' If they didn't supply a path, assume same location as the source workbook.
    ' Not perfect - simply assumes a path has been supplied if a path separator
    ' exists somewhere. Could still be a badly-formed path. And, no check is done
    ' to see if the path actually exists.
    If InStr(1, newFilename, Application.PathSeparator, vbTextCompare) = 0 Then
        newFilename = sourceWorkbook.Path & Application.PathSeparator & newFilename
    End If

    ' Create a new workbook and save as the user requested.
    ' NB This fails if the filename is the same as a workbook that's
    ' already open - it should check for this.
    Set newWorkbook = Application.Workbooks.Add(xlWBATWorksheet)
    newWorkbook.SaveAs Filename:=newFilename, _

    ' Theme fonts and colours don't get copied over with most paste-special operations.
    ' This saves the theme of the source workbook and then loads it into the new workbook.
    ' BUG: Doesn't work!
    'themeTempFilePath = Environ("temp") & Application.PathSeparator & sourceWorkbook.Name & " - Theme.xml"
    'sourceWorkbook.Theme.ThemeFontScheme.Save themeTempFilePath
    'sourceWorkbook.Theme.ThemeColorScheme.Save themeTempFilePath
    'newWorkbook.Theme.ThemeFontScheme.Load themeTempFilePath
    'newWorkbook.Theme.ThemeColorScheme.Load themeTempFilePath
    'On Error Resume Next
    'Kill themeTempFilePath  ' kill = delete in VBA-speak
    'On Error GoTo 0

    ' getWorksheetNameFromObject returns null if the worksheet object doens't
    ' exist
    For Each sht In colSheetObjectsToCopy
        sheetFriendlyName = getWorksheetNameFromObject(sourceWorkbook, sht)
        Application.StatusBar = "VBL Copying " & sheetFriendlyName
        If Not IsNull(sheetFriendlyName) Then
            Select Case copyMethod
                Case "sheet"
                    sourceWorkbook.Sheets(sheetFriendlyName).Copy _
                Case "valuesWithFormatting"
                    newWorkbook.Sheets.Add After:=newWorkbook.Sheets(newWorkbook.Sheets.count), _
                    sheetCount = newWorkbook.Sheets.count
                    newWorkbook.Sheets(sheetCount).Name = sheetFriendlyName
                    ' Copy all cells in current source sheet to the clipboard. Could copy straight
                    ' to the new workbook by specifying the Destination parameter but in this case
                    ' we want to do a paste special as values only and the Copy method doens't allow that.
                    sourceWorkbook.Sheets(sheetFriendlyName).Cells.Copy ' Destination:=newWorkbook.Sheets(newWorkbook.Sheets.Count).[A1]
                    newWorkbook.Sheets(sheetCount).[A1].PasteSpecial Paste:=xlValues
                    newWorkbook.Sheets(sheetCount).[A1].PasteSpecial Paste:=xlFormats
                    newWorkbook.Sheets(sheetCount).Tab.Color = sourceWorkbook.Sheets(sheetFriendlyName).Tab.Color
                    Application.CutCopyMode = False
            End Select
        End If
    Next sht

    Application.StatusBar = False
    Application.ScreenUpdating = True

Android charting libraries

You can use MPAndroidChart.

It's native, free, easy to use, fast and reliable.

Core features, benefits:

  • LineChart, BarChart (vertical, horizontal, stacked, grouped), PieChart, ScatterChart, CandleStickChart (for financial data), RadarChart (spider web chart), BubbleChart
  • Combined Charts (e.g. lines and bars in one)
  • Scaling on both axes (with touch-gesture, axes separately or pinch-zoom)
  • Dragging / Panning (with touch-gesture)
  • Separate (dual) y-axes
  • Highlighting values (with customizeable popup-views)
  • Save chart to SD-Card (as image)
  • Predefined color templates
  • Legends (generated automatically, customizeable)
  • Customizeable Axes (both x- and y-axis)
  • Animations (build up animations, on both x- and y-axis)
  • Limit lines (providing additional information, maximums, ...)
  • Listeners for touch, gesture & selection callbacks
  • Fully customizeable (paints, typefaces, legends, colors, background, dashed lines, ...)
  • mobile database support via MPAndroidChart-Realm library
  • Smooth rendering for up to 10.000 data points in Line- and BarChart
  • Lightweight (method count ~1.4K)
  • Available as .jar file (only 500kb in size)
  • Available as gradle dependency and via maven
  • Good documentation
  • Example Project (code for demo-application)
  • Google-PlayStore Demo Application
  • Widely used, great support on both GitHub and stackoverflow - mpandroidchart
  • Also available for iOS: Charts (API works the same way)
  • Also available for Xamarin: MPAndroidChart.Xamarin


Disclaimer: I am the developer of this library.

Create a simple 10 second countdown

JavaScript has built in to it a function called setInterval, which takes two arguments - a function, callback and an integer, timeout. When called, setInterval will call the function you give it every timeout milliseconds.

For example, if you wanted to make an alert window every 500 milliseconds, you could do something like this.

function makeAlert(){ 
    alert("Popup window!");

setInterval(makeAlert, 500);

However, you don't have to name your function or declare it separately. Instead, you could define your function inline, like this.

setInterval(function(){ alert("Popup window!"); }, 500);

Once setInterval is called, it will run until you call clearInterval on the return value. This means that the previous example would just run infinitely. We can put all of this information together to make a progress bar that will update every second and after 10 seconds, stop updating.

var timeleft = 10;_x000D_
var downloadTimer = setInterval(function(){_x000D_
  if(timeleft <= 0){_x000D_
  document.getElementById("progressBar").value = 10 - timeleft;_x000D_
  timeleft -= 1;_x000D_
}, 1000);
<progress value="0" max="10" id="progressBar"></progress>

Alternatively, this will create a text countdown.

var timeleft = 10;_x000D_
var downloadTimer = setInterval(function(){_x000D_
  if(timeleft <= 0){_x000D_
    document.getElementById("countdown").innerHTML = "Finished";_x000D_
  } else {_x000D_
    document.getElementById("countdown").innerHTML = timeleft + " seconds remaining";_x000D_
  timeleft -= 1;_x000D_
}, 1000);
<div id="countdown"></div>

Java stack overflow error - how to increase the stack size in Eclipse?

When using JBOSS Server, double click on the server:

enter image description here

Go to "Open Launch Configuration"

enter image description here

Then change min and max memory sizes (like 1G, 1m):

enter image description here

C++ equivalent of StringBuffer/StringBuilder?

The C++ way would be to use std::stringstream or just plain string concatenations. C++ strings are mutable so the performance considerations of concatenation are less of a concern.

with regards to formatting, you can do all the same formatting on a stream, but in a different way, similar to cout. or you can use a strongly typed functor which encapsulates this and provides a String.Format like interface e.g. boost::format

Test if element is present using Selenium WebDriver?

I found that this works for Java:

WebDriverWait waiter = new WebDriverWait(driver, 5000);
waiter.until( ExpectedConditions.presenceOfElementLocated(by) );

Start an activity from a fragment

You should use getActivity() to launch activities from fragments

Intent intent = new Intent(getActivity(), mFragmentFavorite.class);

Also, you should be naming classes with caps: MFragmentActivity instead of mFragmentActivity.

How to use in jQuery :not and hasClass() to get a specific element without a class

Use the not function instead:

var lastOpenSite = $(this).siblings().not('.closedTab');

hasClass only tests whether an element has a class, not will remove elements from the selected set matching the provided selector.

Center text output from Graphics.DrawString()

You can use an instance of the StringFormat object passed into the DrawString method to center the text.

See Graphics.DrawString Method and StringFormat Class.

How to update all MySQL table rows at the same time?

The default null value for a field is "not null". So you must set it to "null" before you can set that field value for any record to null. Then you can:

UPDATE `myTable` SET `myField` = null

Is there more to an interface than having the correct methods

What makes interfaces useful is not the fact that "you can change your mind and use a different implementation later and only have to change the one place where the object is created". That's a non-issue.

The real point is already in the name: they define an interface that anyone at all can implement to use all code that operates on that interface. The best example is java.util.Collections which provides all kinds of useful methods that operate exclusively on interfaces, such as sort() or reverse() for List. The point here is that this code can now be used to sort or reverse any class that implements the List interfaces - not just ArrayList and LinkedList, but also classes that you write yourself, which may be implemented in a way the people who wrote java.util.Collections never imagined.

In the same way, you can write code that operates on well-known interfaces, or interfaces you define, and other people can use your code without having to ask you to support their classes.

Another common use of interfaces is for Callbacks. For example, java.swing.table.TableCellRenderer, which allows you to influence how a Swing table displays the data in a certain column. You implement that interface, pass an instance to the JTable, and at some point during the rendering of the table, your code will get called to do its stuff.

How do I protect javascript files?

I think the only way is to put required data on the server and allow only logged-in user to access the data as required (you can also make some calculations server side). This wont protect your javascript code but make it unoperatable without the server side code

Is it safe to use Project Lombok?

I read some opinions about the Lombok and actually I'm using it in some projects.

Well, in the first contact with Lombok I had a bad impression. After some weeks, I started to like it. But after some months I figure out a lot of tiny problems using it. So, my final impression about Lombok is not so positive.

My reasons to think in this way:

  • IDE plugin dependency. The IDE support for Lombok is through plugins. Even working good in most part of the time, you are always a hostage from this plugins to be maintained in the future releases of the IDEs and even the language version (Java 10+ will accelerate the development of the language). For example, I tried to update from Intellij IDEA 2017.3 to 2018.1 and I couldn't do that because there was some problem on the actual lombok plugin version and I needed to wait the plugin be updated... This also is a problem if you would like to use a more alternative IDE that don't have any Lombok plugin support.
  • 'Find usages' problem.. Using Lombok you don't see the generated getter, setter, constructor, builder methods and etc. So, if you are planning to find out where these methods are being used in your project by your IDE, you can't do this only looking for the class that owns this hidden methods.
  • So easy that the developers don't care to break the encapsulation. I know that it's not really a problem from Lombok. But I saw a bigger tendency from the developers to not control anymore what methods needs to be visible or not. So, many times they are just copying and pasting @Getter @Setter @Builder @AllArgsConstructor @NoArgsConstructor annotations block without thinking what methods the class really need to be exposed.
  • Builder Obssession ©. I invented this name (get off, Martin Fowler). Jokes apart, a Builder is so easy to create that even when a class have only two parameters the developers prefer to use @Builder instead of constructor or a static constructor method. Sometimes they even try to create a Builder inside the lombok Builder, creating weird situations like MyClass.builder().name("Name").build().create().
  • Barriers when refactoring. If you are using, for example, a @AllArgsConstructor and need to add one more parameter on the constructor, the IDE can't help you to add this extra parameter in all places (mostly, tests) that are instantiating the class.
  • Mixing Lombok with concrete methods. You can't use Lombok in all scenarios to create a getter/setter/etc. So, you will see these two approaches mixed in your code. You get used to this after some time, but feels like a hack on the language.

Like another answer said, if you are angry about the Java verbosity and use Lombok to deal with it, try Kotlin.

How do I setup the dotenv file in Node.js?

If you use "firebase-functions" to host your sever-side-rendered application, you should be aware of this one:

error: Error: ENOENT: no such file or directory, open 'C:\Codes\url_shortener\functions\.env'

Means you have to store the .env file in the functions folder as well.

Found this one by:


javac: invalid target release: 1.8

Your javac is not pointing to correct java.

Check where your javac is pointing using following command -

update-alternatives --config javac

If it is not pointed to the javac you want to compile with, point it to "/JAVA8_HOME/bin/javac", or which ever java you want to compile with.

How to name variables on the fly?

Don't make data frames. Keep the list, name its elements but do not attach it.

The biggest reason for this is that if you make variables on the go, almost always you will later on have to iterate through each one of them to perform something useful. There you will again be forced to iterate through each one of the names that you have created on the fly.

It is far easier to name the elements of the list and iterate through the names.

As far as attach is concerned, its really bad programming practice in R and can lead to a lot of trouble if you are not careful.

How to change the background color on a input checkbox with css?

I always use pseudo elements :before and :after for changing the appearance of checkboxes and radio buttons. it's works like a charm.

Refer this link for more info



  1. Hide the default checkbox using css rules like visibility:hidden or opacity:0 or position:absolute;left:-9999px etc.
  2. Create a fake checkbox using :before element and pass either an empty or a non-breaking space '\00a0';
  3. When the checkbox is in :checked state, pass the unicode content: "\2713", which is a checkmark;
  4. Add :focus style to make the checkbox accessible.
  5. Done

Here is how I did it.

.box {_x000D_
  background: #666666;_x000D_
  color: #ffffff;_x000D_
  width: 250px;_x000D_
  padding: 10px;_x000D_
  margin: 1em auto;_x000D_
p {_x000D_
  margin: 1.5em 0;_x000D_
  padding: 0;_x000D_
input[type="checkbox"] {_x000D_
  visibility: hidden;_x000D_
label {_x000D_
  cursor: pointer;_x000D_
input[type="checkbox"] + label:before {_x000D_
  border: 1px solid #333;_x000D_
  content: "\00a0";_x000D_
  display: inline-block;_x000D_
  font: 16px/1em sans-serif;_x000D_
  height: 16px;_x000D_
  margin: 0 .25em 0 0;_x000D_
  padding: 0;_x000D_
  vertical-align: top;_x000D_
  width: 16px;_x000D_
input[type="checkbox"]:checked + label:before {_x000D_
  background: #fff;_x000D_
  color: #333;_x000D_
  content: "\2713";_x000D_
  text-align: center;_x000D_
input[type="checkbox"]:checked + label:after {_x000D_
  font-weight: bold;_x000D_
input[type="checkbox"]:focus + label::before {_x000D_
    outline: rgb(59, 153, 252) auto 5px;_x000D_
<div class="content">_x000D_
  <div class="box">_x000D_
      <input type="checkbox" id="c1" name="cb">_x000D_
      <label for="c1">Option 01</label>_x000D_
      <input type="checkbox" id="c2" name="cb">_x000D_
      <label for="c2">Option 02</label>_x000D_
      <input type="checkbox" id="c3" name="cb">_x000D_
      <label for="c3">Option 03</label>_x000D_

Much more stylish using :before and :after

  font-family: sans-serif;  _x000D_
.container {_x000D_
    margin-top: 50px;_x000D_
    margin-left: 20px;_x000D_
    margin-right: 20px;_x000D_
.checkbox {_x000D_
    width: 100%;_x000D_
    margin: 15px auto;_x000D_
    position: relative;_x000D_
    display: block;_x000D_
.checkbox input[type="checkbox"] {_x000D_
    width: auto;_x000D_
    opacity: 0.00000001;_x000D_
    position: absolute;_x000D_
    left: 0;_x000D_
    margin-left: -20px;_x000D_
.checkbox label {_x000D_
    position: relative;_x000D_
.checkbox label:before {_x000D_
    content: '';_x000D_
    position: absolute;_x000D_
    left: 0;_x000D_
    top: 0;_x000D_
    margin: 4px;_x000D_
    width: 22px;_x000D_
    height: 22px;_x000D_
    transition: transform 0.28s ease;_x000D_
    border-radius: 3px;_x000D_
    border: 2px solid #7bbe72;_x000D_
.checkbox label:after {_x000D_
  content: '';_x000D_
    display: block;_x000D_
    width: 10px;_x000D_
    height: 5px;_x000D_
    border-bottom: 2px solid #7bbe72;_x000D_
    border-left: 2px solid #7bbe72;_x000D_
    -webkit-transform: rotate(-45deg) scale(0);_x000D_
    transform: rotate(-45deg) scale(0);_x000D_
    transition: transform ease 0.25s;_x000D_
    will-change: transform;_x000D_
    position: absolute;_x000D_
    top: 12px;_x000D_
    left: 10px;_x000D_
.checkbox input[type="checkbox"]:checked ~ label::before {_x000D_
    color: #7bbe72;_x000D_
.checkbox input[type="checkbox"]:checked ~ label::after {_x000D_
    -webkit-transform: rotate(-45deg) scale(1);_x000D_
    transform: rotate(-45deg) scale(1);_x000D_
.checkbox label {_x000D_
    min-height: 34px;_x000D_
    display: block;_x000D_
    padding-left: 40px;_x000D_
    margin-bottom: 0;_x000D_
    font-weight: normal;_x000D_
    cursor: pointer;_x000D_
    vertical-align: sub;_x000D_
.checkbox label span {_x000D_
    position: absolute;_x000D_
    top: 50%;_x000D_
    -webkit-transform: translateY(-50%);_x000D_
    transform: translateY(-50%);_x000D_
.checkbox input[type="checkbox"]:focus + label::before {_x000D_
    outline: 0;_x000D_
<div class="container"> _x000D_
  <div class="checkbox">_x000D_
     <input type="checkbox" id="checkbox" name="" value="">_x000D_
     <label for="checkbox"><span>Checkbox</span></label>_x000D_
  <div class="checkbox">_x000D_
     <input type="checkbox" id="checkbox2" name="" value="">_x000D_
     <label for="checkbox2"><span>Checkbox</span></label>_x000D_

Get all files that have been modified in git branch

git diff --name-only master...branch-name

to which we want to compare.

Binding an Image in WPF MVVM

If you have a process that already generates and returns an Image type, you can alter the bind and not have to modify any additional image creation code.

Refer to the ".Source" of the image in the binding statement.


<Image Name="imgOpenClose" Source="{Binding ImageOpenClose.Source}"/>

View Model Field

private Image _imageOpenClose;
public Image ImageOpenClose
        return _imageOpenClose;
        _imageOpenClose = value;

Getting time elapsed in Objective-C

You should not rely on [NSDate date] for timing purposes since it can over- or under-report the elapsed time. There are even cases where your computer will seemingly time-travel since the elapsed time will be negative! (E.g. if the clock moved backwards during timing.)

According to Aria Haghighi in the "Advanced iOS Gesture Recognition" lecture of the Winter 2013 Stanford iOS course (34:00), you should use CACurrentMediaTime() if you need an accurate time interval.


#import <QuartzCore/QuartzCore.h>
CFTimeInterval startTime = CACurrentMediaTime();
// perform some action
CFTimeInterval elapsedTime = CACurrentMediaTime() - startTime;


let startTime = CACurrentMediaTime()
// perform some action
let elapsedTime = CACurrentMediaTime() - startTime

The reason is that [NSDate date] syncs on the server, so it could lead to "time-sync hiccups" which can lead to very difficult-to-track bugs. CACurrentMediaTime(), on the other hand, is a device time that doesn't change with these network syncs.

You will need to add the QuartzCore framework to your target's settings.

SQLAlchemy: how to filter date field?

if you want to get the whole period:

    from sqlalchemy import and_, func

    query = DBSession.query(User).filter(and_( >= '1985-01-17'),\
                                     <= '1988-01-17'))

That means range: 1985-01-17 00:00 - 1988-01-17 23:59

form serialize javascript (no framework)

HTMLElement.prototype.serialize = function(){
    var obj = {};
    var elements = this.querySelectorAll( "input, select, textarea" );
    for( var i = 0; i < elements.length; ++i ) {
        var element = elements[i];
        var name =;
        var value = element.value;

        if( name ) {
            obj[ name ] = value;
    return JSON.stringify( obj );

To use like this:

var dataToSend = document.querySelector("form").serialize();

I hope I have helped.

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

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

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

Once you've done that, you then put:

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

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

How do I read any request header in PHP

I was using CodeIgniter and used the code below to get it. May be useful for someone in future.


Is it possible to specify the schema when connecting to postgres with JDBC?

I don't believe there is a way to specify the schema in the connection string. It appears you have to execute

set search_path to 'schema'

after the connection is made to specify the schema.

How to pass variable number of arguments to printf/sprintf

You are looking for variadic functions. printf() and sprintf() are variadic functions - they can accept a variable number of arguments.

This entails basically these steps:

  1. The first parameter must give some indication of the number of parameters that follow. So in printf(), the "format" parameter gives this indication - if you have 5 format specifiers, then it will look for 5 more arguments (for a total of 6 arguments.) The first argument could be an integer (eg "myfunction(3, a, b, c)" where "3" signifies "3 arguments)

  2. Then loop through and retrieve each successive argument, using the va_start() etc. functions.

There are plenty of tutorials on how to do this - good luck!

Protractor : How to wait for page complete after click a button?

With Protractor, you can use the following approach

var EC = protractor.ExpectedConditions;
// Wait for new page url to contain newPageName
browser.wait(EC.urlContains('newPageName'), 10000);

So your code will look something like,


var EC = protractor.ExpectedConditions;
// Wait for new page url to contain efg
ptor.wait(EC.urlContains('efg'), 10000);

expect(ptor.getCurrentUrl()).toEqual(url + 'abc#/efg');

Note: This may not mean that new page has finished loading and DOM is ready. The subsequent 'expect()' statement will ensure Protractor waits for DOM to be available for test.

Reference: Protractor ExpectedConditions

Selenium: WebDriverException:Chrome failed to start: crashed as google-chrome is no longer running so ChromeDriver is assuming that Chrome has crashed

I encountered the exact problem running on docker container (in build environment). After ssh into the container, I tried running the test manually and still encountered

(unknown error: DevToolsActivePort file doesn't exist)
     (The process started from chrome location /usr/bin/google-chrome-stable is 
      no longer running, so ChromeDriver is assuming that Chrome has crashed.)

When I tried running chrome locally /usr/bin/google-chrome-stable, error message

Running as root without --no-sandbox is not supported

I checked my ChromeOptions and it was missing --no-sandbox, which is why it couldn't spawn chrome.

capabilities =
  chromeOptions: { args: %w(headless --no-sandbox disable-gpu window-size=1920,1080) }

Mixed mode assembly is built against version ‘v2.0.50727' of the runtime

For me this was thrown when running unit tests under MSTest (VS2015). Had to add

<startup useLegacyV2RuntimeActivationPolicy="true">


C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\CommonExtensions\Microsoft\TestWindow\TE.ProcessHost.Managed.exe.config

Mixed-Mode Assembly MSTest Failing in VS2015

How exactly does __attribute__((constructor)) work?

Here is a "concrete" (and possibly useful) example of how, why, and when to use these handy, yet unsightly constructs...

Xcode uses a "global" "user default" to decide which XCTestObserver class spews it's heart out to the beleaguered console.

In this example... when I implicitly load this psuedo-library, let's call it... libdemure.a, via a flag in my test target á la..

OTHER_LDFLAGS = -ldemure

I want to..

  1. At load (ie. when XCTest loads my test bundle), override the "default" XCTest "observer" class... (via the constructor function) PS: As far as I can tell.. anything done here could be done with equivalent effect inside my class' + (void) load { ... } method.

  2. run my tests.... in this case, with less inane verbosity in the logs (implementation upon request)

  3. Return the "global" XCTestObserver class to it's pristine state.. so as not to foul up other XCTest runs which haven't gotten on the bandwagon (aka. linked to libdemure.a). I guess this historically was done in dealloc.. but I'm not about to start messing with that old hag.


#define USER_DEFS NSUserDefaults.standardUserDefaults

@interface      DemureTestObserver : XCTestObserver @end
@implementation DemureTestObserver

__attribute__((constructor)) static void hijack_observer() {

/*! here I totally hijack the default logging, but you CAN
    use multiple observers, just CSV them, 
    i.e. "@"DemureTestObserverm,XCTestLog"
  [USER_DEFS setObject:@"DemureTestObserver" 
  [USER_DEFS synchronize];

__attribute__((destructor)) static void reset_observer()  {

  // Clean up, and it's as if we had never been here.
  [USER_DEFS setObject:@"XCTestLog" 
  [USER_DEFS synchronize];


Without the linker flag... (Fashion-police swarm Cupertino demanding retribution, yet Apple's default prevails, as is desired, here)

enter image description here

WITH the -ldemure.a linker flag... (Comprehensible results, gasp... "thanks constructor/destructor"... Crowd cheers) enter image description here

pretty-print JSON using JavaScript

This is nice: from mafintosh

const jsonMarkup = require('json-markup')
const html = jsonMarkup({hello:'world'})
document.querySelector('#myElem').innerHTML = html


<link ref="stylesheet" href="style.css">
<div id="myElem></div>

Example stylesheet can be found here

Find which commit is currently checked out in Git

Use git show, which also shows you the commit message, and defaults to the current commit when given no arguments.

How do I make a Windows batch script completely silent?

Just add a >NUL at the end of the lines producing the messages.

For example,

COPY %scriptDirectory%test.bat %scriptDirectory%test2.bat >NUL

Remove NA values from a vector

Trying ?max, you'll see that it actually has a na.rm = argument, set by default to FALSE. (That's the common default for many other R functions, including sum(), mean(), etc.)

Setting na.rm=TRUE does just what you're asking for:

d <- c(1, 100, NA, 10)
max(d, na.rm=TRUE)

If you do want to remove all of the NAs, use this idiom instead:

d <- d[!]

A final note: Other functions (e.g. table(), lm(), and sort()) have NA-related arguments that use different names (and offer different options). So if NA's cause you problems in a function call, it's worth checking for a built-in solution among the function's arguments. I've found there's usually one already there.

What do pty and tty mean?

A tty is a terminal (it stands for teletype - the original terminals used a line printer for output and a keyboard for input!). A terminal is a basically just a user interface device that uses text for input and output.

A pty is a pseudo-terminal - it's a software implementation that appears to the attached program like a terminal, but instead of communicating directly with a "real" terminal, it transfers the input and output to another program.

For example, when you ssh in to a machine and run ls, the ls command is sending its output to a pseudo-terminal, the other side of which is attached to the SSH daemon.

Visual Studio "Could not copy" .... during build

@Geoff's ( answer is good, but it throws error code 1 on recompile.

Here is what worked for me (2>nul 1>nul on the end + exit 0):

(if exist "$(TargetDir)*old.pdb" del "$(TargetDir)*old.pdb") & (if exist "$(TargetDir)*.pdb" ren "$(TargetDir)*.pdb" *.old.pdb) 2>nul 1>nul
(if exist "$(TargetDir)*old.dll" del "$(TargetDir)*old.dll") & (if exist "$(TargetDir)*.dll" ren "$(TargetDir)*.dll" *.old.dll) 2>nul 1>nul
exit 0

Cannot run Eclipse; JVM terminated. Exit code=13

I just had the same issue, and spend about an hour trying to solve the problem. In the end it was a '#' character in the path.

So I renamed "C:\# IDE\eclipse 3.7\" to "C:\+ IDE\eclipse 3.7\" and that solved the problem.

Java converting int to hex and back again

As Integer.toHexString(byte/integer) is not working when you are trying to convert signed bytes like UTF-16 decoded characters you have to use:

Integer.toString(byte/integer, 16);


String.format("%02X", byte/integer);

reverse you can use

Integer.parseInt(hexString, 16);

Convert string to buffer Node

You can do:

var buf = Buffer.from(bufStr, 'utf8');

But this is a bit silly, so another suggestion would be to copy the minimal amount of code out of the called function to allow yourself access to the original buffer. This might be quite easy or fairly difficult depending on the details of that library.

How do I use regular expressions in bash scripts?

It was changed between 3.1 and 3.2:

This is a terse description of the new features added to bash-3.2 since the release of bash-3.1.

Quoting the string argument to the [[ command's =~ operator now forces string matching, as with the other pattern-matching operators.

So use it without the quotes thus:

if [[ $i =~ 200[78] ]] ; then
    echo "OK"
    echo "not OK"

How to split a string content into an array of strings in PowerShell?

[string[]]$recipients = $address.Split('; ',[System.StringSplitOptions]::RemoveEmptyEntries)

Search an Oracle database for tables with specific column names?

Here is one that we have saved off to findcol.sql so we can run it easily from within SQLPlus

set verify off
clear break
accept colnam prompt 'Enter Column Name (or part of): '
set wrap off
select distinct table_name, 
                data_type || ' (' || 
                decode(data_type,'LONG',null,'LONG RAW',null,
                             ), data_length
                      ) || ')' data_type
  from all_tab_columns
 where column_name like ('%' || upper('&colnam') || '%');
set verify on

System.Data.OracleClient requires Oracle client software version 8.1.7

When we first moved over to Vista with Oracle 10g, we experienced this issue when we installed the Oracle client on our Vista boxes, even when we were running with admin privileges during install.

Oracle brought out a new version of the 10g client ( that was Vista compatible.

I do believe that this was after 11g was released, so it is possible that there is a 'Vista compatible' version for 11g also.

Get class name of object as string in Swift

You can extend NSObjectProtocol in Swift 4 like this :

import Foundation

extension NSObjectProtocol {

    var className: String {
        return String(describing: Self.self)

This will make calculated variable className available to ALL classes. Using this inside a print() in CalendarViewController will print "CalendarViewController" in console.

How to create virtual column using MySQL SELECT?

SELECT only retrieves data from the database, it does not change the table itself.

If you write


"b" is just an alias name in the query. It does not create an extra column. Your result in the example would only contain one column named "b". But the column in the table would stay "a". "b" is just another name.

I don't really understand what you mean with "so I can use it with each item later on". Do you mean later in the select statement or later in your application. Perhaps you could provide some example code.

PHP str_replace replace spaces with underscores

I'll suggest that you use this as it will check for both single and multiple occurrence of white space (as suggested by Lucas Green).

$journalName = preg_replace('/\s+/', '_', $journalName);

instead of:

$journalName = str_replace(' ', '_', $journalName);

copy from one database to another using oracle sql developer - connection failed

The copy command is a SQL*Plus command (not a SQL Developer command). If you have your tnsname entries setup for SID1 and SID2 (e.g. try a tnsping), you should be able to execute your command.

Another assumption is that table1 has the same columns as the message_table (and the columns have only the following data types: CHAR, DATE, LONG, NUMBER or VARCHAR2). Also, with an insert command, you would need to be concerned about primary keys (e.g. that you are not inserting duplicate records).

I tried a variation of your command as follows in SQL*Plus (with no errors):

copy from scott/tiger@db1 to scott/tiger@db2 create new_emp using select * from emp;

After I executed the above statement, I also truncate the new_emp table and executed this command:

copy from scott/tiger@db1 to scott/tiger@db2 insert new_emp using select * from emp;

With SQL Developer, you could do the following to perform a similar approach to copying objects:

  1. On the tool bar, select Tools>Database copy.

  2. Identify source and destination connections with the copy options you would like. enter image description here

  3. For object type, select table(s). enter image description here

  4. Specify the specific table(s) (e.g. table1). enter image description here

The copy command approach is old and its features are not being updated with the release of new data types. There are a number of more current approaches to this like Oracle's data pump (even for tables).

Change the default base url for axios

Putting my two cents here. I wanted to do the same without hardcoding the URL for my specific request. So i came up with this solution.

To append 'api' to my baseURL, I have my default baseURL set as,

axios.defaults.baseURL = '/api/';

Then in my specific request, after explicitly setting the method and url, i set the baseURL to '/'

    baseURL: '/',
   .then(response => {
   .catch(error => {

I am not able launch JNLP applications using "Java Web Start"?

Same solution worked as suggested by hpereira The issue was due to JRE version was 32 bit and not 64 Bit Check with java -version to see if your Java is 64 bit

C:\>java -version
java version "1.8.0_192"
Java(TM) SE Runtime Environment (build 1.8.0_192-b12)
Java HotSpot(TM) **64-Bit Server** VM (build 25.192-b12, mixed mode)

Javascript Print iframe contents only

an alternate option, which may or may not be suitable, but cleaner if it is:

If you always want to just print the iframe from the page, you can have a separate "@media print{}" stylesheet that hides everything besides the iframe. Then you can just print the page normally.

How can I handle the warning of file_get_contents() function in PHP?

The best thing would be to set your own error and exception handlers which will do something usefull like logging it in a file or emailing critical ones.

How to use aria-expanded="true" to change a css property

If you were open to using JQuery, you could modify the background color for any link that has the property aria-expanded set to true by doing the following...

$("a[aria-expanded='true']").css("background-color", "#42DCA3");

Depending on how specific you want to be regarding which links this applies to, you may have to slightly modify your selector.

Setting "checked" for a checkbox with jQuery

You can do this if you have the id to check it

document.getElementById('ElementId').checked = false

And this to uncheck

document.getElementById('ElementId').checked = true

Python math module


import math

at beginning. and then use:

math.sqrt(num)  # or any other function you deem neccessary

javax.servlet.ServletException cannot be resolved to a type in spring web app


worked for me.

Using a different font with twitter bootstrap

First of all you have to include your font in your website (or your CSS, to be more specific) using an appropriate @font-face rule.
From here on there are multiple ways to proceed. One thing I would not do is to edit the bootstrap.css directly - since once you get a newer version your changes will be lost. You do however have the possibility to customize your bootstrap files (there's a customize page on their website). Just enter the name of your font with all the fallback names into the corresponding typography textbox. Of course you will have to do this whenever you get a new or updated version of your bootstrap files.
Another chance you have is to overwrite the bootstrap rules within a different stylesheet. If you do this you just have to use selectors that are as specific as (or more specific than) the bootstrap selectors.
Side note: If you care about browser support a single EOT version of your font might not be sufficient. See for a support table.

Refused to load the script because it violates the following Content Security Policy directive

The probable reason why you get this error is likely because you've added the /build folder to your .gitignore file or generally haven't checked it into Git.

So when you Git push Heroku master, the build folder you're referencing don't get pushed to Heroku. And that's why it shows this error.

That's the reason it works properly locally, but not when you deployed to Heroku.

Handling Dialogs in WPF with MVVM

I've written a fairly comprehensive article about this very topic and also developed a pop-in library for MVVM Dialogs. Strict adherence to MVVM is not only possible but very clean when implemented properly, and it can be easily extended to third-party libraries that don't adhere to it themselves:

Insert multiple rows into single column

I believe this should work for inserting multiple rows:

('Hello'), ('World'),...

Android Firebase, simply get one child object's data

You don't directly read a value. You can set it with .setValue(), but there is no .getValue() on the reference object.

You have to use a listener. If you just want to read the value once, you use ref.addListenerForSingleValueEvent().


Firebase ref = new Firebase("YOUR-URL-HERE/PATH/TO/YOUR/STUFF");
ref.addListenerForSingleValueEvent(new ValueEventListener() {
   public void onDataChange(DataSnapshot dataSnapshot) {
       String value = (String) dataSnapshot.getValue();

       // do your stuff here with value


   public void onCancelled(FirebaseError firebaseError) {



Spark: Add column to dataframe conditionally

Try withColumn with the function when as follows:

val sqlContext = new SQLContext(sc)
import sqlContext.implicits._ // for `toDF` and $""
import org.apache.spark.sql.functions._ // for `when`

val df = sc.parallelize(Seq((4, "blah", 2), (2, "", 3), (56, "foo", 3), (100, null, 5)))
    .toDF("A", "B", "C")

val newDf = df.withColumn("D", when($"B".isNull or $"B" === "", 0).otherwise(1)) shows

|  A|   B|  C|  D|
|  4|blah|  2|  1|
|  2|    |  3|  0|
| 56| foo|  3|  1|
|100|null|  5|  0|

I added the (100, null, 5) row for testing the isNull case.

I tried this code with Spark 1.6.0 but as commented in the code of when, it works on the versions after 1.4.0.

How can I write text on a HTML5 canvas element?

var canvas = document.getElementById("my-canvas");_x000D_
var context = canvas.getContext("2d");_x000D_
context.fillStyle = "blue";_x000D_
context.font = "bold 16px Arial";_x000D_
context.fillText("Zibri", (canvas.width / 2) - 17, (canvas.height / 2) + 8);
#my-canvas {_x000D_
  background: #FF0;_x000D_
<canvas id="my-canvas" width="200" height="120"></canvas>

Foreach loop in java for a custom object list

for(Room room : rooms) {
  //room contains an element of rooms

Reinitialize Slick js after successful ajax call

The best way is you should destroy the slick slider after reinitializing it.

function slickCarousel() {
    infinite: true,
    slidesToShow: 3,
    slidesToScroll: 1
function destroyCarousel() {
  if ($('.skills_section').hasClass('slick-initialized')) {

  type: 'get',
  url: '/public/index',
  dataType: 'script',
  data: data_send,
  success: function() {

Download file inside WebView

Try using download manager, which can help you download everything you want and save you time.

Check those to options:

Option 1 ->

 mWebView.setDownloadListener(new DownloadListener() {
        public void onDownloadStart(String url, String userAgent,
                String contentDisposition, String mimetype,
                long contentLength) {
 Request request = new Request(
                    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "download"); 
                    DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);


Option 2 ->

if(mWebview.getUrl().contains(".mp3") {
 Request request = new Request(
                request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "download"); 
// You can change the name of the downloads, by changing "download" to everything you want, such as the mWebview title...
                DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);


What does the ELIFECYCLE Node.js error mean?

When running Webpack build I was getting similar error because node doesn't understand async await keywords on older versions. I added webpack babel-plugin-transform-async-to-generator and it was solved. This replaces them with promises.

Intermediate language used in scalac?

maybe this will help you out:

or this page:‎

How do I restrict an input to only accept numbers?

I know this is old, but I've created a directive for this purpose in case anyone is looking for an easy solution. Very simple to use.

You can check it out here.

Proper way to make HTML nested list?

Option 2

<li>Choice A</li>
<li>Choice B
    <li>Sub 1</li>
    <li>Sub 2</li>

Nesting Lists - UL

How to change letter spacing in a Textview?

More space:


Less space:


Get next / previous element using JavaScript?

use the nextSibling and previousSibling properties:

<div id="foo1"></div>
<div id="foo2"></div>
<div id="foo3"></div>

document.getElementById('foo2').nextSibling; // #foo3
document.getElementById('foo2').previousSibling; // #foo1

However in some browsers (I forget which) you also need to check for whitespace and comment nodes:

var div = document.getElementById('foo2');
var nextSibling = div.nextSibling;
while(nextSibling && nextSibling.nodeType != 1) {
    nextSibling = nextSibling.nextSibling

Libraries like jQuery handle all these cross-browser checks for you out of the box.

How to display an error message in an ASP.NET Web Application

The errors in ASP.Net are saved on the Server.GetLastError property,

Or i would put a label on the page for displaying the error.

    do something
catch (YourException ex)
    errorLabel.Text = ex.Message;
    errorLabel.Visible = true;

Removing input background colour for Chrome autocomplete?

If you want to keep the autocomplete functionality intact you can use a bit of jQuery to remove Chrome's styling. I wrote a short post about it here:

if (navigator.userAgent.toLowerCase().indexOf("chrome") >= 0) {
        var text = $(this).val();
        var name = $(this).attr('name');
        $('input[name=' + name + ']').val(text);

How to iterate object in JavaScript?

Something like that:

var dictionary = {"data":[{"id":"0","name":"ABC"},{"id":"1", "name":"DEF"}], "images": [{"id":"0","name":"PQR"},{"id":"1","name":"xyz"}]};

for (item in dictionary) {
  for (subItem in dictionary[item]) {

Iterating over Typescript Map


for (let [key, value] of map) {
    console.log(key, value);


for (let entry of Array.from(map.entries())) {
    let key = entry[0];
    let value = entry[1];

Getting a count of objects in a queryset in django

To get the number of votes for a specific item, you would use:

vote_count = Item.objects.filter(votes__contest=contestA).count()

If you wanted a break down of the distribution of votes in a particular contest, I would do something like the following:

contest = Contest.objects.get(pk=contest_id)
votes   = contest.votes_set.select_related()

vote_counts = {}

for vote in votes:
  if not vote_counts.has_key(
    vote_counts[] = {
      'item': vote.item,
      'count': 0

  vote_counts[]['count'] += 1

This will create dictionary that maps items to number of votes. Not the only way to do this, but it's pretty light on database hits, so will run pretty quickly.

I'm trying to use python in powershell

Just eliminate the word "User". It will work.

Postman Chrome: What is the difference between form-data, x-www-form-urlencoded and raw


Note. Please consult RFC2388 for additional information about file uploads, including backwards compatibility issues, the relationship between "multipart/form-data" and other content types, performance issues, etc.

Please consult the appendix for information about security issues for forms.

The content type "application/x-www-form-urlencoded" is inefficient for sending large quantities of binary data or text containing non-ASCII characters. The content type "multipart/form-data" should be used for submitting forms that contain files, non-ASCII data, and binary data.

The content type "multipart/form-data" follows the rules of all multipart MIME data streams as outlined in RFC2045. The definition of "multipart/form-data" is available at the [IANA] registry.

A "multipart/form-data" message contains a series of parts, each representing a successful control. The parts are sent to the processing agent in the same order the corresponding controls appear in the document stream. Part boundaries should not occur in any of the data; how this is done lies outside the scope of this specification.

As with all multipart MIME types, each part has an optional "Content-Type" header that defaults to "text/plain". User agents should supply the "Content-Type" header, accompanied by a "charset" parameter.


This is the default content type. Forms submitted with this content type must be encoded as follows:

Control names and values are escaped. Space characters are replaced by +', and then reserved characters are escaped as described in [RFC1738], section 2.2: Non-alphanumeric characters are replaced by%HH', a percent sign and two hexadecimal digits representing the ASCII code of the character. Line breaks are represented as "CR LF" pairs (i.e., %0D%0A'). The control names/values are listed in the order they appear in the document. The name is separated from the value by=' and name/value pairs are separated from each other by `&'.

application/x-www-form-urlencoded the body of the HTTP message sent to the server is essentially one giant query string -- name/value pairs are separated by the ampersand (&), and names are separated from values by the equals symbol (=). An example of this would be:


The content type "application/x-www-form-urlencoded" is inefficient for sending large quantities of binary data or text containing non-ASCII characters. The content type "multipart/form-data" should be used for submitting forms that contain files, non-ASCII data, and binary data.

Ternary operation in CoffeeScript

a = if true then 5 else 10
a = if false then 5 else 10 

See documentation.

Pad a string with leading zeros so it's 3 characters long in SQL Server 2008

Wrote this because I had requirements for up to a specific length (9). Pads the left with the @pattern ONLY when the input needs padding. Should always return length defined in @pattern.

declare @charInput as char(50) = 'input'

--always handle NULL :)
set @charInput = isnull(@charInput,'')

declare @actualLength as int = len(@charInput)

declare @pattern as char(50) = '123456789'
declare @prefLength as int = len(@pattern)

if @prefLength > @actualLength
    select Left(Left(@pattern, @prefLength-@actualLength) + @charInput, @prefLength)
    select @charInput

Returns 1234input

jQuery append text inside of an existing paragraph tag

I have just discovered a way to append text and its working fine at least.

 var text = 'Put any text here';

You can change text according to your need.

Hope this helps.

How can I get the current time in C#?

DateTime.Now.ToString("HH:mm:ss tt");

this gives it to you as a string.

PKIX path building failed: unable to find valid certification path to requested target

I've run into this a few times and it was due to a certificate chain being incomplete. If you are using the standard java trust store, it may not have a certificate that is needed to complete the certificate chain which is required to validate the certificate of the SSL site you are connecting to.

I ran into this problem with some DigiCert certificates and had to manually add the intermediary cert myself.

Get name of object or class

All we need:

  1. Wrap a constant in a function (where the name of the function equals the name of the object we want to get)
  2. Use arrow functions inside the object

function App(){ // name of my constant is App_x000D_
  return {_x000D_
  a: {_x000D_
    b: {_x000D_
      c: ()=>{ // very important here, use arrow function _x000D_
const obj = new App(); // usage_x000D_
obj.a.b.c(); // App_x000D_
// usage with react props etc, _x000D_
// For instance, we want to pass this callback to some component_x000D_
const myComponent = {};_x000D_
myComponent.customProps = obj.a.b.c;_x000D_
myComponent.customProps(); // App

#1214 - The used table type doesn't support FULLTEXT indexes

*************Resolved - #1214 - The used table type doesn't support FULLTEXT indexes***************

Its Very Simple to resolve this issue. People are answering here in very difficult words which are not easily understandable by the people who are not technical.

So i am mentioning here steps in very simple words will resolve your issue.

1.) Open your .sql file with Notepad by right clicking on file>Edit Or Simply open a Notepad file and drag and drop the file on Notepad and the file will be opened. (Note: Please don't change the extention .sql of file as its still your sql database. Also to keep a copy of your sql file to save yourself from any mishappening)

2.) Click on Notepad Menu Edit > Replace (A Window will be pop us with Find What & Replace With Fields)

3.) In Find What Field Enter ENGINE=InnoDB & In Replace With Field Enter ENGINE=MyISAM

4.) Now Click on Replace All Button

5.) Click CTRL+S or File>Save

6.) Now Upload This File and I am Sure your issue will be resolved....

'this' implicitly has type 'any' because it does not have a type annotation

For method decorator declaration with configuration "noImplicitAny": true, you can specify type of this variable explicitly depends on @tony19's answer

function logParameter(this:any, target: Object, propertyName: string) {

Eclipse jump to closing brace

Place the cursor next to an opening or closing brace and punch Ctrl + Shift + P to find the matching brace. If Eclipse can't find one you'll get a "No matching bracket found" message.

edit: as mentioned by Romaintaz below, you can also get Eclipse to auto-select all of the code between two curly braces simply by double-clicking to the immediate right of a opening brace.

Firebug like plugin for Safari browser

I work a lot with CSS panel and it's too slow in Safari Web Inspector. Apple knows about this problem and promise to fix this bug with freezes, except this thing web tools is much more powerful and convenient than firebug in mozilla, so waiting for fix.

Bootstrap table striped: How do I change the stripe background colour?

Don't customize your bootstrap CSS by directly editing bootstrap CSS file.Instead, I suggest to copy paste bootstrap CSS and save them in a different CSS folder and there you can customize or edit stylings suitable to your needs.

How to handle query parameters in angular 2

The simple way to do that in Angular 7+ is to:

Define a path in your ?-routing.module.ts

{ path: '/yourpage', component: component-name }

Import the ActivateRoute and Router module in your component and inject them in the constructor

contructor(private route: ActivateRoute, private router: Router){ ... }

Subscribe the ActivateRoute to the ngOnInit

ngOnInit() {

    this.route.queryParams.subscribe(params => {
      // {page: '2' }

Provide it to a link:

<a [routerLink]="['/yourpage']" [queryParams]="{ page: 2 }">2</a>

Scroll to bottom of div?

Sometimes the most simple is the best solution: I do not know if this will help, it helped me to scroll it were ever I wanted too. The higher the "y=" is,the more down it scrolls and of course "0" means top, so there for example "1000" could be bottom, or "2000" or "3000" and so on, depending how long your page is. This usually works in a button with onclick or onmouseover.


Best way to track onchange as-you-type in input type="text"?

Method 1: Add an event listener for input:

element.addEventListener("input", myFunction);


Method 2: Define the oninput property with JavaScript:

element.oninput = function()


Method 3: Define the oninput property with HTML:

<input type="text" oninput="myFunction();">

AngularJS resource promise

If you're looking to get promise in resource call, you should use

Regions.query().$q.then(function(){ .... })

Update : the promise syntax is changed in current versions which reads

Regions.query().$promise.then(function(){ ..... })

Those who have downvoted don't know what it was and who first added this promise to resource object. I used this feature in late 2012 - yes 2012.

Try-catch block in Jenkins pipeline script

try like this (no pun intended btw)

script {
  try {
      sh 'do your stuff'
  } catch (Exception e) {
      echo 'Exception occurred: ' + e.toString()
      sh 'Handle the exception!'

The key is to put try...catch in a script block in declarative pipeline syntax. Then it will work. This might be useful if you want to say continue pipeline execution despite failure (eg: test failed, still you need reports..)

Best way to format integer as string with leading zeros?

This is my Python function:

def add_nulls(num, cnt=2):
  cnt = cnt - len(str(num))
  nulls = '0' * cnt
  return '%s%s' % (nulls, num)

Changing the URL in react-router v4 without using Redirect or Link

React Router v4

There's a couple of things that I needed to get this working smoothly.

The doc page on auth workflow has quite a lot of what is required.

However I had three issues

  1. Where does the props.history come from?
  2. How do I pass it through to my component which isn't directly inside the Route component
  3. What if I want other props?

I ended up using:

  1. option 2 from an answer on 'Programmatically navigate using react router' - i.e. to use <Route render> which gets you props.history which can then be passed down to the children.
  2. Use the render={routeProps => <MyComponent {...props} {routeProps} />} to combine other props from this answer on 'react-router - pass props to handler component'

N.B. With the render method you have to pass through the props from the Route component explicitly. You also want to use render and not component for performance reasons (component forces a reload every time).

const App = (props) => (
        render={routeProps => <MyComponent {...props} {...routeProps}>}

const MyComponent = (props) => (
     * @link
     * N.B. I use `props.history` instead of `history`
    <button onClick={() => {
        fakeAuth.signout(() => props.history.push('/foo'))
    }}>Sign out</button>

One of the confusing things I found is that in quite a few of the React Router v4 docs they use MyComponent = ({ match }) i.e. Object destructuring, which meant initially I didn't realise that Route passes down three props, match, location and history

I think some of the other answers here are assuming that everything is done via JavaScript classes.

Here's an example, plus if you don't need to pass any props through you can just use component

class App extends React.Component {
    render () {

class MyComponent extends React.Component {
    render () {
         * @link
         * N.B. I use `props.history` instead of `history`
        <button onClick={() => {
            this.fakeAuth.signout(() => this.props.history.push('/foo'))
        }}>Sign out</button>

Invariant Violation: Objects are not valid as a React child

In my case it was because of a dynamic array which had to be injected at runtime.

I just added the null checks for object and it worked fine.


    <div> {[0]} </div>


let items = (props && && [];
    <div> {items[i]} </div>

Finding rows containing a value (or values) in any column

If you want to find the rows that have any of the values in a vector, one option is to loop the vector (lapply(v1,..)), create a logical index of (TRUE/FALSE) with (==). Use Reduce and OR (|) to reduce the list to a single logical matrix by checking the corresponding elements. Sum the rows (rowSums), double negate (!!) to get the rows with any matches.

indx1 <- !!rowSums(Reduce(`|`, lapply(v1, `==`, df)), na.rm=TRUE)

Or vectorise and get the row indices with which with arr.ind=TRUE

indx2 <- unique(which(Vectorize(function(x) x %in% v1)(df),


I didn't use @kristang's solution as it is giving me errors. Based on a 1000x500 matrix, @konvas's solution is the most efficient (so far). But, this may vary if the number of rows are increased

val <- paste0('M0', 1:1000)
df1 <-, NA), 1000*500, 
  replace=TRUE), ncol=500), stringsAsFactors=FALSE) 
v1 <- sample(val, 200, replace=FALSE)

 konvas <- function() {apply(df1, 1, function(r) any(r %in% v1))}
 akrun1 <- function() {!!rowSums(Reduce(`|`, lapply(v1, `==`, df1)),
 akrun2 <- function() {unique(which(Vectorize(function(x) x %in% 

 microbenchmark(konvas(), akrun1(), akrun2(), unit='relative', times=20L)
 #Unit: relative
 #   expr       min         lq       mean     median         uq      max   neval
 # konvas()   1.00000   1.000000   1.000000   1.000000   1.000000  1.00000    20
 # akrun1() 160.08749 147.642721 125.085200 134.491722 151.454441 52.22737    20
 # akrun2()   5.85611   5.641451   4.676836   5.330067   5.269937  2.22255    20
 # cld
 #  a 
 #  b
 #  a 

For ncol = 10, the results are slighjtly different:

expr       min        lq     mean    median        uq       max    neval
 konvas()  3.116722  3.081584  2.90660  2.983618  2.998343  2.394908    20
 akrun1() 27.587827 26.554422 22.91664 23.628950 21.892466 18.305376    20
 akrun2()  1.000000  1.000000  1.00000  1.000000  1.000000  1.000000    20


 v1 <- c('M017', 'M018')
 df <- structure(list(datetime = c("04.10.2009 01:24:51",
"04.10.2009 01:24:53", 
"04.10.2009 01:24:54", "04.10.2009 01:25:06", "04.10.2009 01:25:07", 
"04.10.2009 01:26:07", "04.10.2009 01:26:27", "04.10.2009 01:27:23", 
"04.10.2009 01:27:30", "04.10.2009 01:27:32", "04.10.2009 01:27:34"
), col1 = c("M017", "M018", "M051", "<NA>", "<NA>", "<NA>", "<NA>", 
"<NA>", "<NA>", "M017", "M051"), col2 = c("<NA>", "<NA>", "<NA>", 
"M016", "M015", "M017", "M017", "M017", "M017", "<NA>", "<NA>"
), col3 = c("<NA>", "<NA>", "<NA>", "<NA>", "<NA>", "<NA>", "<NA>", 
"<NA>", "<NA>", "<NA>", "<NA>"), col4 = c(NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA)), .Names = c("datetime", "col1", "col2", 
"col3", "col4"), class = "data.frame", row.names = c("1", "2", 
"3", "4", "5", "6", "7", "8", "9", "10", "11"))

How do I auto-resize an image to fit a 'div' container?

This solution doesn't stretch the image and fills the whole container, but it cuts some of the image.


 <div><img src="/images/image.png"></div>


div {
    width: 100%;
    height: 10em;
    overflow: hidden;

img {
    min-width: 100%;
    min-height: 100%;

Convert UTF-8 to base64 string

It's a little difficult to tell what you're trying to achieve, but assuming you're trying to get a Base64 string that when decoded is abcdef==, the following should work:

byte[] bytes = Encoding.UTF8.GetBytes("abcdef==");
string base64 = Convert.ToBase64String(bytes);

This will output: YWJjZGVmPT0= which is abcdef== encoded in Base64.


To decode a Base64 string, simply use Convert.FromBase64String(). E.g.

string base64 = "YWJjZGVmPT0=";
byte[] bytes = Convert.FromBase64String(base64);

At this point, bytes will be a byte[] (not a string). If we know that the byte array represents a string in UTF8, then it can be converted back to the string form using:

string str = Encoding.UTF8.GetString(bytes);

This will output the original input string, abcdef== in this case.

TensorFlow, "'module' object has no attribute 'placeholder'"

It may be the typo if you incorrectly wrote the placeholder word. In my case I misspelled it as placehoder and got the error like this: AttributeError: 'module' object has no attribute 'placehoder'

json Uncaught SyntaxError: Unexpected token :

I had the same problem and the solution was to encapsulate the json inside this function


.... your json ...


Python convert decimal to hex

non recursive approach to convert decimal to hex

def to_hex(dec):

    hex_str = ''
    hex_digits = ('0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F')
    rem = dec % 16

    while dec >= rem:
        remainder = dec % 16
        quotient = dec / 16
        if quotient == 0:
            hex_str += hex_digits[remainder]
            hex_str += str(remainder)
        dec = quotient

    return hex_str[::-1] # reverse the string

Creating a copy of an object in C#

The easiest way to do this is writing a copy constructor in the MyClass class.

Something like this:

namespace Example
    class MyClass
        public int val;

        public MyClass()

        public MyClass(MyClass other)
            val = other.val;

The second constructor simply accepts a parameter of his own type (the one you want to copy) and creates a new object assigned with the same value

class Program
    static void Main(string[] args)
        MyClass objectA = new MyClass();
        MyClass objectB = new MyClass(objectA);
        objectA.val = 10;
        objectB.val = 20;
        Console.WriteLine("objectA.val = {0}", objectA.val);
        Console.WriteLine("objectB.val = {0}", objectB.val);


objectA.val = 10

objectB.val = 20               

Output PowerShell variables to a text file

I usually construct custom objects in these loops, and then add these objects to an array that I can easily manipulate, sort, export to CSV, etc.:

# Construct an out-array to use for data export
$OutArray = @()

# The computer loop you already have
foreach ($server in $serverlist)
        # Construct an object
        $myobj = "" | Select "computer", "Speed", "Regcheck"

        # Fill the object
        $ = $computer
        $myobj.speed = $speed
        $myobj.regcheck = $regcheck

        # Add the object to the out-array
        $outarray += $myobj

        # Wipe the object just to be sure
        $myobj = $null

# After the loop, export the array to CSV
$outarray | export-csv "somefile.csv"

Simple pthread! C++

When compiling with G++, remember to put the -lpthread flag :)