Programs & Examples On #Dynamic scope

Dynamic scoping is a method of variable scoping where variables are bound based upon the call stack, instead of where they are defined.

How can I access an internal class from an external assembly?

Without access to the type (and no "InternalsVisibleTo" etc) you would have to use reflection. But a better question would be: should you be accessing this data? It isn't part of the public type contract... it sounds to me like it is intended to be treated as an opaque object (for their purposes, not yours).

You've described it as a public instance field; to get this via reflection:

object obj = ...
string value = (string)obj.GetType().GetField("test").GetValue(obj);

If it is actually a property (not a field):

string value = (string)obj.GetType().GetProperty("test").GetValue(obj,null);

If it is non-public, you'll need to use the BindingFlags overload of GetField/GetProperty.

Important aside: be careful with reflection like this; the implementation could change in the next version (breaking your code), or it could be obfuscated (breaking your code), or you might not have enough "trust" (breaking your code). Are you spotting the pattern?

Understanding React-Redux and mapStateToProps()

You got the first part right:

Yes mapStateToProps has the Store state as an argument/param (provided by react-redux::connect) and its used to link the component with certain part of the store state.

By linking I mean the object returned by mapStateToProps will be provided at construction time as props and any subsequent change will be available through componentWillReceiveProps.

If you know the Observer design pattern it's exactly that or small variation of it.

An example would help make things clearer:

import React, {
} from 'react-native';

class ItemsContainer extends Component {
    constructor(props) {

        this.state = {
            items: props.items, //provided by connect@mapStateToProps
            filteredItems: this.filterItems(props.items, props.filters),

    componentWillReceiveProps(nextProps) {
            filteredItems: this.filterItems(this.state.items, nextProps.filters),

    filterItems = (items, filters) => { /* return filtered list */ }

    render() {
        return (
                // display the filtered items

module.exports = connect(
    (state) => ({
        items: state.App.Items.List,
        filters: state.App.Items.Filters,
        //the State.App & state.App.Items.List/Filters are reducers used as an example.
    // mapDispatchToProps,  that's another subject

There can be another react component called itemsFilters that handle the display and persisting the filter state into Redux Store state, the Demo component is "listening" or "subscribed" to Redux Store state filters so whenever filters store state changes (with the help of filtersComponent) react-redux detect that there was a change and notify or "publish" all the listening/subscribed components by sending the changes to their componentWillReceiveProps which in this example will trigger a refilter of the items and refresh the display due to the fact that react state has changed.

Let me know if the example is confusing or not clear enough to provide a better explanation.

As for: This means that the state as consumed by your target component can have a wildly different structure from the state as it is stored on your store.

I didn't get the question, but just know that the react state (this.setState) is totally different from the Redux Store state!

The react state is used to handle the redraw and behavior of the react component. The react state is contained to the component exclusively.

The Redux Store state is a combination of Redux reducers states, each is responsible of managing a small portion app logic. Those reducers attributes can be accessed with the help of react-redux::connect@mapStateToProps by any component! Which make the Redux store state accessible app wide while component state is exclusive to itself.

Read only file system on Android

Sometimes you get the error because the destination location in phone are not exist. For example, some android phone external storage location is /storage/emulated/legacy instead of /storage/emulated/0.

Excel Date to String conversion

In Excel 2010, marg's answer only worked for some of the data I had in my spreadsheet (it was imported). The following solution worked on all data.

Sub change()
    toText Selection
End Sub

Sub toText(target As range)
Dim cell As range
Dim txt As String
    For Each cell In target
        txt = cell.text
        cell.NumberFormat = "@"
        cell.Value2 = txt
    Next cell
End Sub

Detecting input change in jQuery?

There are jQuery events like keyup and keypress which you can use with input HTML Elements. You could additionally use the blur() event.

Replace substring with another substring C++

using std::string;

string string_replace( string src, string const& target, string const& repl)
    // handle error situations/trivial cases

    if (target.length() == 0) {
        // searching for a match to the empty string will result in 
        //  an infinite loop
        //  it might make sense to throw an exception for this case
        return src;

    if (src.length() == 0) {
        return src;  // nothing to match against

    size_t idx = 0;

    for (;;) {
        idx = src.find( target, idx);
        if (idx == string::npos)  break;

        src.replace( idx, target.length(), repl);
        idx += repl.length();

    return src;

Since it's not a member of the string class, it doesn't allow quite as nice a syntax as in your example, but the following will do the equivalent:

test = string_replace( string_replace( test, "abc", "hij"), "def", "klm")

Android - styling seek bar

With the Material Component Library version 1.2.0 you can use the new Slider component.


You can override the default color using something like:

  <style name="slider_red">
    <item name="colorPrimary">#......</item>

enter image description here

Otherwise you can use these attribute in the layout to define a color or a color selector:


or you can use a custom style:

 <style name="customSlider" parent="Widget.MaterialComponents.Slider">
    <item name="activeTrackColor">@color/....</item>
    <item name="inactiveTrackColor">@color/....</item>
    <item name="thumbColor">@color/....</item>

How to implement the Softmax function in Python

This also works with np.reshape.

   def softmax( scores):
        Compute softmax scores given the raw output from the model

        :param scores: raw scores from the model (N, num_classes)
            prob: softmax probabilities (N, num_classes)
        prob = None

        exponential = np.exp(
            scores - np.max(scores, axis=1).reshape(-1, 1)
        )  # subract the largest number
        prob = exponential / exponential.sum(axis=1).reshape(-1, 1)


        return prob

Limit to 2 decimal places with a simple pipe

Simple solution

{{ orderTotal | number : '1.2-2'}}

//output like this

// public orderTotal = 220.45892221

//   {{ orderTotal | number : '1.2-2'}} 

// final Output
//  220.45

In jQuery how can I set "top,left" properties of an element with position values relative to the parent and not the document?

I found that if the value passed is a string type, it must be followed by 'px' (i.e. 90px), where if the value is an integer, it will append the px automatically. the width and height properties are more forgiving (either type works).

var x = "90";
var y = "120"
$(selector).css( { left: x, top: y } )        //doesn't work
$(selector).css( { left: x + "px", top: y + "px" } )        //does work

x = 90;
y = 120;
$(selector).css( { left: x, top: y } )        //does work

getCurrentPosition() and watchPosition() are deprecated on insecure origins

You could use the API for this (it's my service). It's free for up to 1,000 req/day (with or without SSL support). It gives you coordinates, name and more. Here's an example:

  "ip": "",
  "hostname": "No Hostname",
  "city": "Oakland",
  "region": "California",
  "country": "US",
  "loc": "37.7350,-122.2088",
  "org": "AS21928 T-Mobile USA, Inc.",
  "postal": "94621"

Here's an example which constructs a coords object with the API response that matches what you get from getCurrentPosition():

$.getJSON('', function(response) { 
    var loc = response.loc.split(',');
    var coords = {
        latitude: loc[0],
        longitude: loc[1]

And here's a detailed example that shows how you can use it as a fallback for getCurrentPosition():

function do_something(coords) {
    // Do something with the coords here

navigator.geolocation.getCurrentPosition(function(position) { 
    function(failure) {
        $.getJSON('', function(response) { 
        var loc = response.loc.split(',');
        var coords = {
            latitude: loc[0],
            longitude: loc[1]

See for more details.

CSS - make div's inherit a height

As already mentioned this can't be done with floats, they can't inherit heights, they're unaware of their siblings so for example the side two floats don't know the height of the centre content, so they can't inherit from anything.

Usually inherited height has to come from either an element which has an explicit height or if height: 100%; has been passed down through the display tree to it.. The only thing I'm aware of that passes on height which hasn't come from top of the "tree" is an absolutely positioned element - so you could for example absolutely position all the top right bottom left sides and corners (you know the height and width of the corners anyway) And as you seem to know the widths (of left/right borders) and heights of top/bottom) borders, and the widths of the top/bottom centers, are easy at 100% - the only thing that needs calculating is the height of the right/left sides if the content grows -

This you can do, even without using all four positioning co-ordinates which IE6 /7 doesn't support

I've put up an example based on what you gave, it does rely on a fixed width (your frame), but I think it could work with a flexible width too? the uses of this could be cool for those fancy image borders we can't get support for until multiple background images or image borders become fully available.. who knows, I was playing, so just sticking it out there!

proof of concept example is here

Why "net use * /delete" does not work but waits for confirmation in my PowerShell script?

Try this:

net use * /delete /y

The /y key makes it select Yes in prompt silently

How to get the current time in Python

You can use time.strftime():

>>> from time import gmtime, strftime
>>> strftime("%Y-%m-%d %H:%M:%S", gmtime())
'2009-01-05 22:14:39'

How can I declare dynamic String array in Java

The Array.newInstance(Class<?> componentType, int length) method is to be used to create an array with dynamically length.

Multi-dimensional arrays can be created similarly with the Array.newInstance(Class<?> componentType, int... dimensions) method.

Flask at first run: Do not use the development server in a production environment

When running the python file, you would normally do this

This will display these messages.

To avoid these messsages. Inside the CLI (Command Line Interface), run these commands.

export FLASK_ENV=development
export FLASK_DEBUG=0
flask run

This should work perfectlly. :) :)

How to split page into 4 equal parts?

Similar to other posts, but with an important distinction to make this work inside a div. The simpler answers aren't very copy-paste-able because they directly modify div or draw over the entire page.

The key here is that the containing div dividedbox has relative positioning, allowing it to sit nicely in your document with the other elements, while the quarters within have absolute positioning, giving you vertical/horizontal control inside the containing div.

As a bonus, text is responsively centered in the quarters.


  <meta charset="utf-8">
  <title>Box model</title>
  <link rel="stylesheet" href="style.css">

  <h1 id="title">Title Bar</h1>
  <div id="dividedbox">
    <div class="quarter" id="NW">
    <div class="quarter" id="NE">
    <div class="quarter" id="SE">
    <div class="quarter" id="SW">



html, body { height:95%;} /* Important to make sure your divs have room to grow in the document */
#title { background: lightgreen}
#dividedbox { position: relative; width:100%; height:95%}   /* for div growth */
.quarter {position: absolute; width:50%; height:50%;  /* gives quarters their size */
  display: flex; justify-content: center; align-items: center;} /* centers text */
#NW { top:0;    left:0;     background:orange;     }
#NE { top:0;    left:50%;   background:lightblue;  }
#SW { top:50%;  left:0;     background:green;      }
#SE { top:50%;  left:50%;   background:red;        }

How do I tell if a variable has a numeric value in Perl?

rexep not perfect... this is:

use Try::Tiny;

sub is_numeric {
  my ($x) = @_;
  my $numeric = 1;
  try {
    use warnings FATAL => qw/numeric/;
    0 + $x;
  catch {
    $numeric = 0;
  return $numeric;

Can I use Twitter Bootstrap and jQuery UI at the same time?

Yes you can use both. js bootstrap from twitter is a collection of jquery plugins. There shohuldn't be any conflict with jQuery UI.

Regarding bandwidth overload, it really depends on how you handle the requests to load all of your js files. if you really dont want to make multiple requests to the server to request for each file, just append them together and minimize. Or you probably can get rid of some js bootstrap plugins you dont need. it is very modular.

Java Regex to Validate Full Name allow only Spaces and Letters

check this out.

String name validation only accept alphabets and spaces
public static boolean validateLetters(String txt) {

    String regx = "^[a-zA-Z\\s]+$";
    Pattern pattern = Pattern.compile(regx,Pattern.CASE_INSENSITIVE);
    Matcher matcher = pattern.matcher(txt);
    return matcher.find();


How to create my json string by using C#?

To convert any object or object list into JSON, we have to use the function JsonConvert.SerializeObject.

The below code demonstrates the use of JSON in an ASP.NET environment:

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using Newtonsoft.Json;
using System.Collections.Generic;

namespace JSONFromCS
    public partial class _Default : System.Web.UI.Page
        protected void Page_Load(object sender, EventArgs e1)
            List<Employee> eList = new List<Employee>();
            Employee e = new Employee();
            e.Name = "Minal";
            e.Age = 24;


            e = new Employee();
            e.Name = "Santosh";
            e.Age = 24;


            string ans = JsonConvert.SerializeObject(eList, Formatting.Indented);

            string script = "var employeeList = {\"Employee\": " + ans+"};";
            script += "for(i = 0;i<employeeList.Employee.length;i++)";
            script += "{";
            script += "alert ('Name : ='+employeeList.Employee[i].Name+' 
            Age : = '+employeeList.Employee[i].Age);";
            script += "}";

            ClientScriptManager cs = Page.ClientScript;
            cs.RegisterStartupScript(Page.GetType(), "JSON", script, true);
    public class Employee
        public string Name;
        public int Age;

After running this program, you will get two alerts

In the above example, we have created a list of Employee object and passed it to function "JsonConvert.SerializeObject". This function (JSON library) will convert the object list into JSON format. The actual format of JSON can be viewed in the below code snippet:

{ "Maths" : [ {"Name"     : "Minal",        // First element
                             "Marks"     : 84,
                             "age"       : 23 },
                             "Name"      : "Santosh",    // Second element
                             "Marks"     : 91,
                             "age"       : 24 }
              "Science" :  [ 
                             "Name"      : "Sahoo",     // First Element
                             "Marks"     : 74,
                             "age"       : 27 }, 
                             "Name"      : "Santosh",    // Second Element
                             "Marks"     : 78,
                             "age"       : 41 }


  • {} - acts as 'containers'

  • [] - holds arrays

  • : - Names and values are separated by a colon

  • , - Array elements are separated by commas

This code is meant for intermediate programmers, who want to use C# 2.0 to create JSON and use in ASPX pages.

You can create JSON from JavaScript end, but what would you do to convert the list of object into equivalent JSON string from C#. That's why I have written this article.

In C# 3.5, there is an inbuilt class used to create JSON named JavaScriptSerializer.

The following code demonstrates how to use that class to convert into JSON in C#3.5.

JavaScriptSerializer serializer = new JavaScriptSerializer()
return serializer.Serialize(YOURLIST);   

So, try to create a List of arrays with Questions and then serialize this list into JSON

GET parameters in the URL with CodeIgniter

Do this below. Worked for me. I took values from a select box and another textbox. Then on button click I took the entire data in Javascript function and redirected using javascript.

//Search Form
$(document).ready (function($){
    $("#searchbtn").click(function showAlert(e){
        var cat = $('#category').val();
        var srch = $('#srch').val();

            alert("Search is empty :(");
            var url = baseurl+'categories/search/'+cat+'/'+srch;            

The above code worked for me.

Excel VBA - select multiple columns not in sequential order

Range("A:B,D:E,G:H").Select can help

Edit note: I just saw you have used different column sequence, I have updated my answer

Rubymine: How to make Git ignore .idea files created by Rubymine

Try git rm -r --cached .idea in your terminal. It disables the change tracking.

PHP date() format when inserting into datetime in MySQL

Here's an alternative solution: if you have the date in PHP as a timestamp, bypass handling it with PHP and let the DB take care of transforming it by using the FROM_UNIXTIME function.

mysql> insert into a_table values(FROM_UNIXTIME(1231634282));
Query OK, 1 row affected (0.00 sec)

mysql> select * from a_table;

| a_date              |
| 2009-01-10 18:38:02 |

Where is Ubuntu storing installed programs?

If you installed the package with the Ubuntu package manager (apt, synaptic, dpkg or similar), you can get information about the installed package with

dpkg -L <package_name>

Get Return Value from Stored procedure in

If you want to to know how to return a value from stored procedure to Visual Basic.NET. Please read this tutorial: How to return a value from stored procedure

I used the following stored procedure to return the value.

CREATE PROCEDURE usp_get_count





Date Difference in php on days?

Below code will give the output for number of days, by taking out the difference between two dates..

$str = "Jul 02 2013";
$str = strtotime(date("M d Y ")) - (strtotime($str));
echo floor($str/3600/24);

Aligning text and image on UIButton with imageEdgeInsets and titleEdgeInsets

The swift 4.2 version of solution would be the following:

let spacing: CGFloat = 10 // the amount of spacing to appear between image and title
self.button?.imageEdgeInsets = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: spacing)
self.button?.titleEdgeInsets = UIEdgeInsets(top: 0, left: spacing, bottom: 0, right: 0)

Output an Image in PHP

(Expanding on the accepted answer...)

I needed to:

  1. log views of a jpg image and an animated gif, and,
  2. ensure that the images are never cached (so every view is logged), and,
  3. also retain the original file extensions.

I accomplished this by creating a "secondary" .htaccess file in the sub-folder where the images are located.
The file contains only one line:

AddHandler application/x-httpd-lsphp .jpg .jpeg .gif

In the same folder, I placed the two 'original' image files (we'll call them orig.jpg and orig.gif), as well as two variations of the [simplified] script below (saved as myimage.jpg and myimage.gif)...

  error_reporting(0); //hide errors (displaying one would break the image)

  //get user IP and the pseudo-image's URL
  if(isset($_SERVER['REMOTE_ADDR'])) {$ip =$_SERVER['REMOTE_ADDR'];}else{$ip= '(unknown)';}
  if(isset($_SERVER['REQUEST_URI'])) {$url=$_SERVER['REQUEST_URI'];}else{$url='(unknown)';}

  //log the visit
  require_once('connect.php');            //file with db connection info
  $conn = new mysqli($servername, $username, $password, $dbname);
  if (!$conn->connect_error) {         //if connected then save mySQL record
   $conn->query("INSERT INTO imageclicks (image, ip) VALUES ('$url', '$ip');");
     $conn->close();  //(datetime is auto-added to table with default of 'now')

  //display the image
  $imgfile='orig.jpg';                             // or 'orig.gif'
  header('Content-Type: image/jpeg');              // or 'image/gif'
  header('Content-Length: '.filesize($imgfile));
  header('Cache-Control: no-cache');

The images render (or animate) normally and can be called in any of the normal ways for images (like an <img> tag), and will save a record of the visiting IP, while invisible to the user.

How to remove all click event handlers using jQuery?


What is the difference between mocking and spying when using Mockito?

[Test double types]

Mock vs Spy

Mock is a bare double object. This object has the same methods signatures but realisation is empty and return default value - 0 and null

Spy is a cloned double object. New object is cloned based on a real object but you have a possibility to mock it

class A {
    String foo1() {
        return "RealString_1";

    String foo2() {
        return "RealString_2";

    void foo3() { foo4(); }

    void foo4() { }
public void testMockA() {
    A mockA = Mockito.mock(A.class);

    String result1 = mockA.foo1();
    String result2 = mockA.foo2();

    assertEquals("MockedString", result1);
    assertEquals(null, result2);

    //Case 2

    verify(mockA, never()).foo4();

public void testSpyA() {
    A spyA = Mockito.spy(new A());


    String result1 = spyA.foo1();
    String result2 = spyA.foo2();

    assertEquals("MockedString", result1);
    assertEquals("RealString_2", result2);

    //Case 2


How to rename a table column in Oracle 10g

alter table table_name rename column oldColumn to newColumn;

Getting only response header from HTTP POST using curl

For long response bodies (and various other similar situations), the solution I use is always to pipe to less, so

curl -i | less


curl -s -D - | less

will do the job.

Debugging Stored Procedure in SQL Server 2008

MSDN has provided easy way to debug the stored procedure. Please check this link-
How to: Debug Stored Procedures

How to get form values in Symfony2 controller

If you're using Symfony 2 security management, you don't need to get posted values, you only need to manage form template (see documentation).

If you aren't using Symfony 2 security management, I advise you strongly to use it. If you don't want to or if you can't, can you give us the LoginType's sources ?

Getting value of HTML Checkbox from onclick/onchange events

The short answer:

Use the click event, which won't fire until after the value has been updated, and fires when you want it to:

<label><input type='checkbox' onclick='handleClick(this);'>Checkbox</label>

function handleClick(cb) {
  display("Clicked, new value = " + cb.checked);

Live example | Source

The longer answer:

The change event handler isn't called until the checked state has been updated (live example | source), but because (as Tim Büthe points out in the comments) IE doesn't fire the change event until the checkbox loses focus, you don't get the notification proactively. Worse, with IE if you click a label for the checkbox (rather than the checkbox itself) to update it, you can get the impression that you're getting the old value (try it with IE here by clicking the label: live example | source). This is because if the checkbox has focus, clicking the label takes the focus away from it, firing the change event with the old value, and then the click happens setting the new value and setting focus back on the checkbox. Very confusing.

But you can avoid all of that unpleasantness if you use click instead.

I've used DOM0 handlers (onxyz attributes) because that's what you asked about, but for the record, I would generally recommend hooking up handlers in code (DOM2's addEventListener, or attachEvent in older versions of IE) rather than using onxyz attributes. That lets you attach multiple handlers to the same element and lets you avoid making all of your handlers global functions.

An earlier version of this answer used this code for handleClick:

function handleClick(cb) {
  setTimeout(function() {
    display("Clicked, new value = " + cb.checked);
  }, 0);

The goal seemed to be to allow the click to complete before looking at the value. As far as I'm aware, there's no reason to do that, and I have no idea why I did. The value is changed before the click handler is called. In fact, the spec is quite clear about that. The version without setTimeout works perfectly well in every browser I've tried (even IE6). I can only assume I was thinking about some other platform where the change isn't done until after the event. In any case, no reason to do that with HTML checkboxes.

How do I `jsonify` a list in Flask?

josonify works..but if you intend to just pass an array without the 'results' key, you can use json library from python. The following conversion works for me..

 import json

 def test_json():
 list = [
        {'a': 1, 'b': 2},
        {'a': 5, 'b': 10}
 return json.dumps(list))

AngularJS is rendering <br> as text not as a newline

I could be wrong because I've never used Angular, but I believe you are probably using ng-bind, which will create just a TextNode.

You will want to use ng-bind-html instead.

Update: It looks like you'll need to use ng-bind-html-unsafe='q.category'

Here's a demo:

assembly to compare two numbers

The basic technique (on most modern systems) is to subtract the two numbers and then to check the sign bit of the result, i.e. see if the result is greater than/equal to/less than zero. In the assembly code instead of getting the result directly (into a register), you normally just branch depending on the state:

; Compare r1 and r2
    CMP $r1, $r2
    JLT lessthan
    ; print "r1 >= r2" somehow
    JMP l1
    ; print "r1 < r2" somehow

npm install -g less does not work: EACCES: permission denied

Another option is to download and install a new version using an installer.

sqlalchemy filter multiple columns

A generic piece of code that will work for multiple columns. This can also be used if there is a need to conditionally implement search functionality in the application.

search_key = "abc"
search_args = [col.ilike('%%%s%%' % search_key) for col in ['col1', 'col2', 'col3']]
query = Query(table).filter(or_(*search_args))

Note: the %% are important to skip % formatting the query.

How do I use variables in Oracle SQL Developer?

Simple answer NO.

However you can achieve something similar by running the following version using bind variables:

SELECT * FROM Employees WHERE EmployeeID = :EmpIDVar 

Once you run the query above in SQL Developer you will be prompted to enter value for the bind variable EmployeeID.

How to check a Long for null in java

Of course Primitive types cannot be null. But in Java 8 you can use Objects.isNull(longValue) to check. Ex. If(Objects.isNull(longValue))

Write bytes to file

This example reads 6 bytes into a byte array and writes it to another byte array. It does an XOR operation with the bytes so that the result written to the file is the same as the original starting values. The file is always 6 bytes in size, since it writes at position 0.

using System;
using System.IO;

namespace ConsoleApplication1
    class Program
        static void Main()
        byte[] b1 = { 1, 2, 4, 8, 16, 32 };
        byte[] b2 = new byte[6];
        byte[] b3 = new byte[6];
        byte[] b4 = new byte[6];

        FileStream f1;
        f1 = new FileStream("test.txt", FileMode.Create, FileAccess.Write);

        // write the byte array into a new file
        f1.Write(b1, 0, 6);

        // read the byte array
        f1 = new FileStream("test.txt", FileMode.Open, FileAccess.Read);

        f1.Read(b2, 0, 6);

        // make changes to the byte array
        for (int i = 1; i < b2.Length; i++)
            b2[i] = (byte)(b2[i] ^ (byte)10); //xor 10

        f1 = new FileStream("test.txt", FileMode.Open, FileAccess.Write);
        // write the new byte array into the file
        f1.Write(b2, 0, 6);

        f1 = new FileStream("test.txt", FileMode.Open, FileAccess.Read);

        // read the byte array
        f1.Read(b3, 0, 6);

        // make changes to the byte array
        for (int i = 1; i < b3.Length; i++)
            b4[i] = (byte)(b3[i] ^ (byte)10); //xor 10

        f1 = new FileStream("test.txt", FileMode.Open, FileAccess.Write);

        // b4 will have the same values as b1
        f1.Write(b4, 0, 6);

npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for [email protected]

It's a warning, not an error. It occurs because fsevents is an optional dependency, used only when project is run on macOS environment (the package provides 'Native Access to Mac OS-X FSEvents').

And since you're running your project on Windows, fsevents is skipped as irrelevant.

There is a PR to fix this behaviour here:

SQL Server: How to use UNION with two queries that BOTH have a WHERE clause?

The answer is misleading because it attempts to fix a problem that is not a problem. You actually CAN have a WHERE CLAUSE in each segment of a UNION. You cannot have an ORDER BY except in the last segment. Therefore, this should work...

select top 2 t1.ID, t1.ReceivedDate
from Table t1
where t1.Type = 'TYPE_1'
-----remove this-- order by ReceivedDate desc
select top 2 t2.ID,  t2.ReceivedDate --- add second column
  from Table t2
 where t2.Type = 'TYPE_2'
order by ReceivedDate desc

Rails find_or_create_by more than one attribute?

In Rails 4 you could do:

GroupMember.find_or_create_by(member_id: 4, group_id: 7)

And use where is different:

GroupMember.where(member_id: 4, group_id: 7).first_or_create

This will call create on GroupMember.where(member_id: 4, group_id: 7):

GroupMember.where(member_id: 4, group_id: 7).create

On the contrary, the find_or_create_by(member_id: 4, group_id: 7) will call create on GroupMember:

GroupMember.create(member_id: 4, group_id: 7)

Please see this relevant commit on rails/rails.

What is the correct wget command syntax for HTTPS with username and password?

I have found that wget does not properly authenticate with some servers, perhaps because it is only HTTP 1.0 compliant. In such cases, curl (which is HTTP 1.1 compliant) usually does the trick:

curl -o <filename-to-save-as> -u <username>:<password> <url>

Setting POST variable without using form

You can do it using jQuery. Example:

<script src=""></script>

        url : "next.php",
        type: "POST",
        data : "name=Denniss",
        success: function(data)
            //data - response from server

How to get only filenames within a directory using c#?

You could use the DirectoryInfo and FileInfo classes.

//GetFiles on DirectoryInfo returns a FileInfo object.
var pdfFiles = new DirectoryInfo("C:\\Documents").GetFiles("*.pdf");

//FileInfo has a Name property that only contains the filename part.
var firstPdfFilename = pdfFiles[0].Name;

How to clone a Date object?

Use the Date object's getTime() method, which returns the number of milliseconds since 1 January 1970 00:00:00 UTC (epoch time):

var date = new Date();
var copiedDate = new Date(date.getTime());

In Safari 4, you can also write:

var date = new Date();
var copiedDate = new Date(date);

...but I'm not sure whether this works in other browsers. (It seems to work in IE8).

Git fails when pushing commit to github

Looks like a server issue (i.e. a "GitHub" issue).
If you look at this thread, it can happen when the git-http-backend gets a corrupted heap.(and since they just put in place a smart http support...)
But whatever the actual cause is, it may also be related with recent sporadic disruption in one of the GitHub fileserver.

Do you still see this error message? Because if you do:

  • check your local Git version (and upgrade to the latest one)
  • report this as a GitHub bug.

Note: the Smart HTTP Support is a big deal for those of us behind an authenticated-based enterprise firewall proxy!

From now on, if you clone a repository over the http:// url and you are using a Git client version 1.6.6 or greater, Git will automatically use the newer, better transport mechanism.
Even more amazing, however, is that you can now push over that protocol and clone private repositories as well. If you access a private repository, or you are a collaborator and want push access, you can put your username in the URL and Git will prompt you for the password when you try to access it.

Older clients will also fall back to the older, less efficient way, so nothing should break - just newer clients should work better.

So again, make sure to upgrade your Git client first.

Input type for HTML form for integer

If you're using HTML5, you should use the input type number. If you are using xhtml or html 4, input type should be text.

how to stop a for loop

Use break and continue to do this. Breaking nested loops can be done in Python using the following:

for a in range(...):
   for b in range(..):
      if some condition:
         # break the inner loop
      # will be called if the previous loop did not end with a `break` 
   # but here we end up right after breaking the inner loop, so we can
   # simply break the outer loop as well

Another way is to wrap everything in a function and use return to escape from the loop.

How to change value of a request parameter in laravel

If you need to update a property in the request, I recommend you to use the replace method from Request class used by Laravel

$request->replace(['property to update' => $newValue]);

How to enable C++11/C++0x support in Eclipse CDT?

When using a cross compiler, I often get advanced custom build systems meticulously crafted by colleagues. I use "Makefile Project with Existing code" so most of the other answers are not applicable.

At the start of the project, I have to specify that I'm using a cross compiler in the wizard for "Makefile Project with Existing Code". The annoying thing is that in the last 10 or so years, the cross compiler button on that wizard doesn't prompt for where the cross compiler is. So in a step that fixes the C++ problem and the cross compiler problem, I have to go to the providers tab as mentioned by answers like @ravwojdyla above, but the provider I have to select is the cross-compiler provider. Then in the command box I put the full path to the compiler and I add -std=gnu++11 for the C++ standard I want to have support for. This works out as well as can be expected.

You can do this to an existing project. The only thing you might need to do is rerun the indexer.

I have never had to add the experimental flag or override __cplusplus's definition. The only thing is, if I have a substantial amount of modern C code, I have nowhere to put the C-specific standard option.

And for when things are going really poorly, getting a parser log, using that command in the Indexer submenu, can be very informative.

libxml install error using pip

If you have installed the libxml2 and libxslt, maybe you need to create a symbolic link between libxml2 and libxslt path to python2.6 include path. Also you can try to add INCLUDE environment argument. Because the gcc command only search this path: -I/usr/include/python2.6.

MVC Razor Hidden input and passing values

First of all ASP.NET MVC does not work the same way WebForms does. You don't have the whole runat="server" thing. MVC does not offer the abstraction layer that WebForms offered. Probabaly you should try to understand what controllers and actions are and then you should look at model binding. Any beginner level tutorial about MVC shows how you can pass data between the client and the server.

Index inside map() function

You will be able to get the current iteration's index for the map method through its 2nd parameter.


const list = [ 'h', 'e', 'l', 'l', 'o'];, index) => {
  console.log("The current iteration is: " + index);
  console.log("The current element is: " + currElement);
  return currElement; //equivalent to list[index]


The current iteration is: 0 <br>The current element is: h

The current iteration is: 1 <br>The current element is: e

The current iteration is: 2 <br>The current element is: l

The current iteration is: 3 <br>The current element is: l 

The current iteration is: 4 <br>The current element is: o

See also:


callback - Function that produces an element of the new Array, taking three arguments:

1) currentValue
The current element being processed in the array.

2) index
The index of the current element being processed in the array.

3) array
The array map was called upon.

Which programming language for cloud computing?

Of the languages you mention Java, PHP, Python, Ruby, Perl are certainly more platform independent than C/C++ (and ASP.NET).

Lots of platform-specific differences also come from what libraries are available for a given platform.

In practice however, I think you will always develop on the same or at least very similar platform (operating system flavour) as the system where your code will run, i.e. the cloud will not take source code and compile it for you before running it.

Personally I would go for Java or Python (probably also Ruby) as they have a vast number of libraries available for all kinds of tasks and are very platform independent.

Serving static web resources in Spring Boot & Spring Security application

This may be an answer (for spring boot 2) and a question at the same time. It seems that in spring boot 2 combined with spring security everything (means every route/antmatcher) is protected by default if you use an individual security mechanism extended from


If you don´t use an individual security mechanism, everything is as it was?

In older spring boot versions (1.5 and below) as Andy Wilkinson states in his above answer places like public/** or static/** are permitted by default.

So to sum this question/answer up - if you are using spring boot 2 with spring security and have an individual security mechanism you have to exclusivley permit access to static contents placed on any route. Like so:

public class SpringSecurityConfiguration extends WebSecurityConfigurerAdapter {

private final ThdAuthenticationProvider thdAuthenticationProvider;

private final ThdAuthenticationDetails thdAuthenticationDetails;

 * Overloaded constructor.
 * Builds up the needed dependencies.
 * @param thdAuthenticationProvider a given authentication provider
 * @param thdAuthenticationDetails  given authentication details
public SpringSecurityConfiguration(@NonNull ThdAuthenticationProvider thdAuthenticationProvider,
                                   @NonNull ThdAuthenticationDetails thdAuthenticationDetails) {
    this.thdAuthenticationProvider = thdAuthenticationProvider;
    this.thdAuthenticationDetails = thdAuthenticationDetails;

 * Creates the AuthenticationManager with the given values.
 * @param auth the AuthenticationManagerBuilder
public void configureGlobal(AuthenticationManagerBuilder auth) {


 * Configures the http Security.
 * @param http HttpSecurity
 * @throws Exception a given exception
protected void configure(HttpSecurity http) throws Exception {


            .defaultSuccessUrl("/bundle/index", true)
            .accessDeniedHandler(new CustomAccessDeniedHandler());


Please mind this line of code, which is new:


If you use spring boot 1.5 and below you don´t need to permit these locations (static/public/webjars etc.) explicitly.

Here is the official note, what has changed in the new security framework as to old versions of itself:

Security changes in Spring Boot 2.0 M4

I hope this helps someone. Thank you! Have a nice day!

SQL Server: What is the difference between CROSS JOIN and FULL OUTER JOIN?

One thing that might not always be obvious to some is that a cross join with an empty table (or result set) results in empty table (M x N; hence M x 0 = 0)

A full outer join will always have rows unless both M and N are 0.

What is the difference between JOIN and UNION?


A join is used for displaying columns with the same or different names from different tables. The output displayed will have all the columns shown individually. That is, the columns will be aligned next to each other.


The UNION set operator is used for combining data from two tables which have columns with the same datatype. When a UNION is performed the data from both tables will be collected in a single column having the same datatype.

For example:

See the two tables shown below:

Table t1
Articleno article price manufacturer_id
1 hammer 3 $ 1
2 screwdriver 5 $ 2

Table t2
manufacturer_id manufacturer
1 ABC Gmbh

Now for performing a JOIN type the query is shown below.

SELECT articleno, article, manufacturer
FROM t1 JOIN t2 ON (t1.manufacturer_id =

articelno article manufacturer
1 hammer ABC GmbH
2 screwdriver DEF Co KG

That is a join.

UNION means that you have to tables or resultset with the same amount and type of columns and you add this to tables/resultsets together. Look at this example:

Table year2006
Articleno article price manufacturer_id
1 hammer 3 $ 1
2 screwdriver 5 $ 2

Table year2007
Articleno article price manufacturer_id
1 hammer 6 $ 3
2 screwdriver 7 $ 4

SELECT articleno, article, price, manufactruer_id
FROM year2006
SELECT articleno, article, price, manufacturer_id
FROM year2007

articleno article price manufacturer_id
1 hammer 3 $ 1
2 screwdriver 5 $ 2
1 hammer 6 $ 3
2 screwdriver 7 $ 4

Create Map in Java

I use such kind of a Map population thanks to Java 9. In my honest opinion, this approach provides more readability to the code.

  public static void main(String[] args) {
    Map<Integer, Point2D.Double> map = Map.of(
        1, new Point2D.Double(1, 1),
        2, new Point2D.Double(2, 2),
        3, new Point2D.Double(3, 3),
        4, new Point2D.Double(4, 4));

How to get system time in Java without creating a new Date

Use System.currentTimeMillis() or System.nanoTime().

Python: Finding differences between elements of a list

>>> t
[1, 3, 6]
>>> [j-i for i, j in zip(t[:-1], t[1:])]  # or use itertools.izip in py2k
[2, 3]

How to open a second activity on click of button in android app

Button btn = (Button) findViewById(;

btn.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        Intent myIntent = new Intent(MainActivity.this, MainActivity2.class);

The answer for the complete noob from a complete noob: MainActivity is the name of the first activity. MainActivity2 is the name of the second activity. button1 is the I.D of the button in xml for MainActivity Activity.

html "data-" attribute as javascript parameter

you might use default parameters in your function and then just pass the entire dataset itself, since the dataset is already a DOMStringMap Object

<div data-uid="aaa" data-name="bbb" data-value="ccc"

const fun = ({uid:'ddd', name:'eee', value:'fff', other:'default'} = {}) { 

that way, you can deal with any data-values that got set in the html tag, or use defaults if they weren't set - that kind of thing

maybe not in this situation, but in others, it might be advantageous to put all your preferences in a single data-attribute

<div data-all='{"uid":"aaa","name":"bbb","value":"ccc"}'

there are probably more terse ways of doing that, if you already know certain things about the order of the data

<div data-all="aaa,bbb,ccc" onclick="fun(this.dataset.all.split(','))">

Regex for not empty and not whitespace

/^$|\s+/ if this matched, there's whitespace or its empty.

Owl Carousel Won't Autoplay

Owl Carousel version matters a lot, as of now (2nd Aug 2020) the version is 2.3.4 and the right options for autoplay are:

    autoplay : true,
    autoplayTimeout: 3000,//Autoplay interval timeout.
    loop:true,//Infinity loop. Duplicate last and first items to get loop illusion.
    items:1 //The number of items you want to see on the screen.

Read more Owl configurations

How to check if memcache or memcached is installed for PHP?

The best approach in this case is to use extension_loaded() or function_exists() they are equally as fast.

You can see evidence here:

Bear in mind that some PHP extensions such as APC have php.ini settings that can disable them even though the extension may be loaded. Here is an example of how to check against that also:

Hope this helps.

Add User to Role ASP.NET Identity

Are you looking for something like this:

RoleManager = new RoleManager<IdentityRole>(new RoleStore<IdentityRole>(new MyDbContext()));
var str = RoleManager.Create(new IdentityRole(roleName));

Also check User Identity

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock'

Solutions revolve around:

  • changing MySQL's permissions

    sudo chown -R _mysql:mysql /usr/local/var/mysql
  • Starting a MySQL process

    sudo mysql.server start

Just to add on a lot of great and useful answers that have been provided here and from many different posts, try specifying the host if the above commands did not resolve this issue for you, i.e

mysql -u root -p h127.0.0.1

Aligning a button to the center

margin: 50%; 

You can adjust the percentage as needed. It seems to work for me in responsive emails.

Enterprise app deployment doesn't work on iOS 7.1

The universal solution is to connect your device to Mac and to observe what's going on during installation. I got an error:

Could not load download manifest with underlying error: Error Domain=NSURLErrorDomain Code=-1202 "Cannot connect to the Store" UserInfo=0x146635d0 {NSLocalizedDescription=Cannot connect to the Store, NSLocalizedRecoverySuggestion=Would you like to connect to the server anyway?, NSLocalizedFailureReason=A secure connection could not be established. Please check your Date & Time settings., NSErrorFailingURLStringKey=, NSUnderlyingError=0x14678880 "The certificate for this server is invalid. You might be connecting to a server that is pretending to be “” which could put your confidential information at risk.", NSURLErrorFailingURLPeerTrustErrorKey=, NSErrorFailingURLKey=}

There was even the suggestion in that error to check date settings. For some reason the date was 1 January 1970. Setting correct date solved the problem.

Printing integer variable and string on same line in SQL

You may try this one,

declare @Number INT = 5                            
print 'There are ' + CONVERT(VARCHAR, @Number) + ' alias combinations did not match a record'

Encrypt Password in Configuration Files?

Try using ESAPIs Encryption methods. Its easy to configure and you can also easily change your keys.


1)encrypt 2)decrypt 3)sign 4)unsign 5)hashing 6)time based signatures and much more with just one library.

Jackson - Deserialize using generic class

Just write a static method in Util class. I am reading a Json from a file. you can give String also to readValue

public static <T> T convertJsonToPOJO(String filePath, Class<?> target) throws JsonParseException, JsonMappingException, IOException, ClassNotFoundException {
        ObjectMapper objectMapper = new ObjectMapper();
        return objectMapper.readValue(new File(filePath), objectMapper .getTypeFactory().constructCollectionType(List.class, Class.forName(target.getName())));


List<TaskBean> list =  Util.<List<TaskBean>>convertJsonToPOJO("E:/J2eeWorkspaces/az_workspace_svn/az-client-service/dir1/dir2/filename.json", TaskBean.class);

Count all duplicates of each value

You'd want the COUNT operator.


How to install npm peer dependencies automatically?

The project npm-install-peers will detect peers and install them.

As of v1.0.1 it doesn't support writing back to the package.json automatically, which would essentially solve our need here.

Please add your support to issue in flight:

CSS3 background image transition

You can use pseudo element to get the effect you want like I did in that Fiddle.


.title a {
    display: block;
    width: 340px;
    height: 338px;
    color: black;
    position: relative;
.title a:after {
    background: url( repeat;
    content: "";
    opacity: 0;
    width: inherit;
    height: inherit;
    position: absolute;
    top: 0;
    left: 0;
    transition: opacity 1s ease-in-out;
    -webkit-transition: opacity 1s ease-in-out;
    -moz-transition: opacity 1s ease-in-out;
    -o-transition: opacity 1s ease-in-out;
.title a:hover:after{   
    opacity: 1;


<div class="title">
    <a href="#">HYPERLINK</a>

Is there an advantage to use a Synchronized Method instead of a Synchronized Block?

Synchronized methods can be checked using reflection API. This can be useful for testing some contracts, such as all methods in model are synchronized.

The following snippet prints all the synchronized methods of Hashtable:

for (Method m : Hashtable.class.getMethods()) {
        if (Modifier.isSynchronized(m.getModifiers())) {

Simple CSS: Text won't center in a button

The problem is that buttons render differently across browsers. In Firefox, 24px is sufficient to cover the default padding and space allowed for your "A" character and center it. In IE and Chrome, it does not, so it defaults to the minimum value needed to cover the left padding and the text without cutting it off, but without adding any additional width to the button.

You can either increase the width, or as suggested above, alter the padding. If you take away the explicit width, it should work too.

How to drop a PostgreSQL database if there are active connections to it?

PostgreSQL 13 introduced FORCE option.


DROP DATABASE drops a database ... Also, if anyone else is connected to the target database, this command will fail unless you use the FORCE option described below.


Attempt to terminate all existing connections to the target database. It doesn't terminate if prepared transactions, active logical replication slots or subscriptions are present in the target database.


How do you generate a random double uniformly distributed between 0 and 1 from C++?

You could try the Mersenne Twister algorithm.

It has a good blend of speed and randomness, and a GPL implementation.

How to return 2 values from a Java method?

First, it would be better if Java had tuples for returning multiple values.

Second, code the simplest possible Pair class, or use an array.

But, if you do need to return a pair, consider what concept it represents (starting with its field names, then class name) - and whether it plays a larger role than you thought, and if it would help your overall design to have an explicit abstraction for it. Maybe it's a code hint...
Please Note: I'm not dogmatically saying it will help, but just to look, to see if it does... or if it does not.

Is there a null-coalescing (Elvis) operator or safe navigation operator in javascript?

Jumping in very late, there's a proposal[1] for optional chaining currently at stage 2, with a babel plugin[2] available. It's not currently in any browser I am aware of.


How to change button color with tkinter

When you do self.button = Button(...).grid(...), what gets assigned to self.button is the result of the grid() command, not a reference to the Button object created.

You need to assign your self.button variable before packing/griding it. It should look something like this:

self.button = Button(self,text="Click Me",command=self.color_change,bg="blue")
self.button.grid(row = 2, column = 2, sticky = W)

Active Directory LDAP Query by sAMAccountName and Domain

"Domain" is not a property of an LDAP object. It is more like the name of the database the object is stored in.

So you have to connect to the right database (in LDAP terms: "bind to the domain/directory server") in order to perform a search in that database.

Once you bound successfully, your query in it's current shape is all you need.

BTW: Choosing "ObjectCategory=Person" over "ObjectClass=user" was a good decision. In AD, the former is an "indexed property" with excellent performance, the latter is not indexed and a tad slower.

Indexing vectors and arrays with +:

This is another way to specify the range of the bit-vector.

x +: N, The start position of the vector is given by x and you count up from x by N.

There is also

x -: N, in this case the start position is x and you count down from x by N.

N is a constant and x is an expression that can contain iterators.

It has a couple of benefits -

  1. It makes the code more readable.

  2. You can specify an iterator when referencing bit-slices without getting a "cannot have a non-constant value" error.

How to change the icon of an Android app in Eclipse?

You can find an easy guide here

The step are 2: - Copy the icon in the correct folder/folders - Change the AndroidManifest.xml

Angular 4 img src is not found

@Annk you can make a variable in the __component.ts file

myImage : string = "";

and inside the __.component.html file you can use one of those 3 methods :

1 .

<div> <img src="{{myImage}}"> </div>

2 .

<div> <img [src]="myImage"/> </div>

3 .

<div> <img bind-src="myImage"/> </div>

Differences between git pull origin master & git pull origin/master

git pull = git fetch + git merge origin/branch

git pull and git pull origin branch only differ in that the latter will only "update" origin/branch and not all origin/* as git pull does.

git pull origin/branch will just not work because it's trying to do a git fetch origin/branch which is invalid.

Question related: git fetch + git merge origin/master vs git pull origin/master

Regular Expression: Allow letters, numbers, and spaces (with at least one letter or number)

^[ _]*[A-Z0-9][A-Z0-9 _]*$

You can optionally have some spaces or underscores up front, then you need one letter or number, and then an arbitrary number of numbers, letters, spaces or underscores after that.

Something that contains only spaces and underscores will fail the [A-Z0-9] portion.

C - The %x format specifier

%08x means that every number should be printed at least 8 characters wide with filling all missing digits with zeros, e.g. for '1' output will be 00000001

Event when window.location.href changes

There is a default onhashchange event that you can use.

Documented HERE

And can be used like this:

function locationHashChanged( e ) {
    console.log( location.hash );
    console.log( e.oldURL, e.newURL );
    if ( location.hash === "#pageX" ) {

window.onhashchange = locationHashChanged;

If the browser doesn't support oldURL and newURL you can bind it like this:

//let this snippet run before your hashChange event binding code
if( !window.HashChangeEvent )( function() {
    let lastURL = document.URL;
    window.addEventListener( "hashchange", function( event ) {
        Object.defineProperty( event, "oldURL", { enumerable: true, configurable: true, value: lastURL } );
        Object.defineProperty( event, "newURL", { enumerable: true, configurable: true, value: document.URL } );
        lastURL = document.URL;
    } );
} () );

What's the difference between ng-model and ng-bind

$scope.testingModel = "This is ModelData.If you change textbox data it will reflected here..because model is two way binding reflected in both.";_x000D_
$scope.testingBind = "This is BindData.You can't change this beacause it is binded with html..In above textBox i tried to use bind, but it is not working because it is one way binding.";            _x000D_
div input{_x000D_
width:600px;  _x000D_
<script src=""></script>_x000D_
<script src=""></script>_x000D_
<head>Diff b/w model and bind</head>_x000D_
<body data-ng-app="testApp">_x000D_
    <div data-ng-controller="testCTRL">_x000D_
        Model-Data : <input type="text" data-ng-model="testingModel">_x000D_
          <input type="text" data-ng-bind="testingBind">_x000D_
          <p ng-bind="testingBind"></p>_x000D_

Get latitude and longitude based on location name with Google Autocomplete API

The below is the code that i used. It's working perfectly.

var geo = new google.maps.Geocoder;
geo.geocode({'address':address},function(results, status){
    if (status == google.maps.GeocoderStatus.OK) {              
        var myLatLng = results[0].geometry.location;

        // Add some code to work with myLatLng              

    } else {
        alert("Geocode was not successful for the following reason: " + status);

Hope this will help.

Exposing the current state name with ui router

Use Timeout

$timeout(function () { console.log($state.current, 'this is working fine'); }, 100);

See -

Excel - programm cells to change colour based on another cell

Use conditional formatting.

You can enter a condition using any cell you like and a format to apply if the formula is true.

How to gettext() of an element in Selenium Webdriver

You need to print the result of the getText(). You're currently printing the object TxtBoxContent.

getText() will only get the inner text of an element. To get the value, you need to use getAttribute().

WebElement TxtBoxContent = driver.findElement(;
System.out.println("Printing " + TxtBoxContent.getAttribute("value"));

Loop through a date range with JavaScript

Let us assume you got the start date and end date from the UI and stored it in the scope variable in the controller.

Then declare an array which will get reset on every function call so that on the next call for the function the new data can be stored.

var dayLabel = [];

Remember to use new Date(your starting variable) because if you dont use the new date and directly assign it to variable the setDate function will change the origional variable value in each iteration`

for (var d = new Date($scope.startDate); d <= $scope.endDate; d.setDate(d.getDate() + 1)) {
                dayLabel.push(new Date(d));

How to get element value in jQuery

  <div class="inter">
      <p>Liste des Produits</p>
          <li><a href="#1">P1</a></li>
          <li><a href="#2">P2</a></li>
          <li><a href="#3">P3</a></li>

            $(".inter li").bind(
            "click", function(){

How to add buttons at top of map fragment API v2 layout

extending de Almeida's answer I am editing code little bit here. since previous code was hiding gps location icon I did following way which worked better.

 <LinearLayout xmlns:android=""


    android:padding="4dp" >

        android:textColor="@drawable/textcolor_radiobutton" />
        android:background="#aaa" />

        android:textColor="@drawable/textcolor_radiobutton" />

        android:background="#aaa" />

        android:textColor="@drawable/textcolor_radiobutton" />
        android:background="#aaa" />

        android:textColor="@drawable/textcolor_radiobutton" />

    android:scrollbars="vertical" />

Checking if a string is empty or null in Java

This way you check if the string is not null and not empty, also considering the empty spaces:

boolean isEmpty = str == null || str.trim().length() == 0;
if (isEmpty) {
    // handle the validation

How to do the Recursive SELECT query in MySQL?

If you want to be able to have a SELECT without problems of the parent id having to be lower than child id, a function could be used. It supports also multiple children (as a tree should do) and the tree can have multiple heads. It also ensure to break if a loop exists in the data.

I wanted to use dynamic SQL to be able to pass the table/columns names, but functions in MySQL don't support this.


CREATE FUNCTION `isSubElement`(pParentId INT, pId INT) RETURNS int(11)
DECLARE isChild,curId,curParent,lastParent int;
SET isChild = 0;
SET curId = pId;
SET curParent = -1;
SET lastParent = -2;

WHILE lastParent <> curParent AND curParent <> 0 AND curId <> -1 AND curParent <> pId AND isChild = 0 DO
    SET lastParent = curParent;
    SELECT ParentId from `test` where id=curId limit 1 into curParent;

    IF curParent = pParentId THEN
        SET isChild = 1;
    END IF;
    SET curId = curParent;

RETURN isChild;

Here, the table test has to be modified to the real table name and the columns (ParentId,Id) may have to be adjusted for your real names.

Usage :

SET @wantedSubTreeId = 3;
SELECT * FROM test WHERE isSubElement(@wantedSubTreeId,id) = 1 OR ID = @wantedSubTreeId;

Result :

3   7   k
5   3   d
9   3   f
1   5   a

SQL for test creation :

  `Id` int(11) NOT NULL,
  `ParentId` int(11) DEFAULT NULL,
  `Name` varchar(300) NOT NULL,

insert into test (id, parentid, name) values(3,7,'k');
insert into test (id, parentid, name) values(5,3,'d');
insert into test (id, parentid, name) values(9,3,'f');
insert into test (id, parentid, name) values(1,5,'a');
insert into test (id, parentid, name) values(6,2,'o');
insert into test (id, parentid, name) values(2,8,'c');

EDIT : Here is a fiddle to test it yourself. It forced me to change the delimiter using the predefined one, but it works.

How to set cellpadding and cellspacing in table with CSS?

The padding inside a table-divider (TD) is a padding property applied to the cell itself.


td, th {padding:0}

The spacing in-between the table-dividers is a space between cell borders of the TABLE. To make it effective, you have to specify if your table cells borders will 'collapse' or be 'separated'.


table, td, th {border-collapse:separate}
table {border-spacing:6px}

Try this : ( 27 100 results )

How to Animate Addition or Removal of Android ListView Rows

Have you considered animating a sweep to the right? You could do something like drawing a progressively larger white bar across the top of the list item, then removing it from the list. The other cells would still jerk into place, but it'd better than nothing.

How to handle the modal closing event in Twitter Bootstrap?

If you want specifically do something when click on close button exactly like you described:

<a href="#" class="btn close_link" data-dismiss="modal">Close</a>

you need to attach an event using css selector:

$(document).on('click', '[data-dismiss="modal"]', function(){what you want to do})

But if you want to do something when modal close, you can use the already wrote tips

ImportError: No module named enum

Please use --user at end of this, it is working fine for me.

pip install enum34 --user

How to return the output of stored procedure into a variable in sql server

With the Return statement from the proc, I needed to assign the temp variable and pass it to another stored procedure. The value was getting assigned fine but when passing it as a parameter, it lost the value. I had to create a temp table and set the variable from the table (SQL 2008)

From this: 
declare @anID int
exec @anID = dbo.StoredProc_Fetch @ID, @anotherID, @finalID
exec dbo.ADifferentStoredProc @anID (no value here)

To this:
declare @t table(id int) 
declare @anID int
insert into @t exec dbo.StoredProc_Fetch @ID, @anotherID, @finalID
set @anID= (select Top 1 * from @t)

'namespace' but is used like a 'type'

if the error is

Line 26:
Line 27: @foreach (Customers customer in Model) Line 28: { Line 29:

give the full name space
like @foreach (Start.Models.customer customer in Model)

AndroidStudio: Failed to sync Install build tools

I had the same issue, with Build Tools revision 24.0.0-rc4. The fix was to install the package using the command line.

~/Android/Sdk| ls -1 build-tools/
~/Android/Sdk| ./tools/android list sdk -a | grep "SDK Build-tools"
   4- Android SDK Build-tools, revision 24 rc4
   5- Android SDK Build-tools, revision 23.0.3
   6- Android SDK Build-tools, revision 23.0.2
   7- Android SDK Build-tools, revision 23.0.1
   8- Android SDK Build-tools, revision 23 (Obsolete)
~/Android/Sdk| ./tools/android update sdk -a -u -t 4
~/Android/Sdk| ls -1 build-tools/

(note that 4 in the android update sdk command above refers to the preceding list's number for the desired version, found at the beginning of the line).

The directory build-tools/24.0.0-rc4/ had been created when I installed the package from Android Studio's SDK Manager. The above method created build-tools/24.0.0-preview/.

My app-level build.gradle script uses the -rc4 version, as specified in the setup guide:

android {
    compileSdkVersion 'android-N'
    buildToolsVersion '24.0.0-rc4'

I do not understand the correlation between -rc4 and -preview or why specifying 24.0.0-rc4 picks up the -preview package, but it did fix the issue for me.

URL rewriting with PHP

You can essentially do this 2 ways:

The .htaccess route with mod_rewrite

Add a file called .htaccess in your root folder, and add something like this:

RewriteEngine on
RewriteRule ^/?Some-text-goes-here/([0-9]+)$ /picture.php?id=$1

This will tell Apache to enable mod_rewrite for this folder, and if it gets asked a URL matching the regular expression it rewrites it internally to what you want, without the end user seeing it. Easy, but inflexible, so if you need more power:

The PHP route

Put the following in your .htaccess instead: (note the leading slash)

FallbackResource /index.php

This will tell it to run your index.php for all files it cannot normally find in your site. In there you can then for example:

$path = ltrim($_SERVER['REQUEST_URI'], '/');    // Trim leading slash(es)
$elements = explode('/', $path);                // Split path on slashes
if(empty($elements[0])) {                       // No path elements means home
} else switch(array_shift($elements))             // Pop off first item and switch
    case 'Some-text-goes-here':
        ShowPicture($elements); // passes rest of parameters to internal function
    case 'more':
        header('HTTP/1.1 404 Not Found');

This is how big sites and CMS-systems do it, because it allows far more flexibility in parsing URLs, config and database dependent URLs etc. For sporadic usage the hardcoded rewrite rules in .htaccess will do fine though.

Virtual member call in a constructor

There's a difference between C++ and C# in this specific case. In C++ the object is not initialized and therefore it is unsafe to call a virutal function inside a constructor. In C# when a class object is created all its members are zero initialized. It is possible to call a virtual function in the constructor but if you'll might access members that are still zero. If you don't need to access members it is quite safe to call a virtual function in C#.

How to debug in Django, the good way?

I find Visual Studio Code is awesome for debugging Django apps. The standard python launch.json parameters run python with the debugger attached, so you can set breakpoints and step through your code as you like.

how to create a window with two buttons that will open a new window

You add your ActionListener twice to button. So correct your code for button2 to

  JButton button2 = new JButton("hello agin2");
  button2.addActionListener (new Action2());//note the button2 here instead of button

Furthermore, perform your Swing operations on the correct thread by using EventQueue.invokeLater

Searching a list of objects in Python

You should add a __eq__ and a __hash__ method to your Data class, it could check if the __dict__ attributes are equal (same properties) and then if their values are equal, too.

If you did that, you can use

test = Data()
test.n = 5

found = test in myList

The in keyword checks if test is in myList.

If you only want to a a n property in Data you could use:

class Data(object):
    __slots__ = ['n']
    def __init__(self, n):
        self.n = n
    def __eq__(self, other):
        if not isinstance(other, Data):
            return False
        if self.n != other.n:
            return False
        return True
    def __hash__(self):
        return self.n

    myList = [ Data(1), Data(2), Data(3) ]
    Data(2) in myList  #==> True
    Data(5) in myList  #==> False

Get json value from response

Use safely-turning-a-json-string-into-an-object

var jsonString = '{"id":"2231f87c-a62c-4c2c-8f5d-b76d11942301"}';

var jsonObject = (new Function("return " + jsonString))();


How to pass data to all views in Laravel 5?

You have two options:

1. Share via ?Boot function in App\Providers\AppServiceProvider:

public function boot()
  view()->share('key', 'value');

And access $key variable in any view file.

Note: Remember that you can't access current Session, Auth, Route data here. This option is good only if you want to share static data. Suppose you want to share some data based on the current user , route, or any custom session variable you won't be able to do with this.

2. Use of a helper class:

Create a helper class anywhere in your application and register it in Alias array in app.php file in config folder.

 'aliases' => [ 
  'Helper' => App\HelperClass\Helper::class,

and create Helper.php in HelperClass folder within App folder:

namespace App\HelperClass;
class Helper
    public static function Sample()
        //Your Code Here

and access it anywhere like Helper::Sample().

You will not be restricted here to use Auth, Route, Session, or any other classes.

How to change a table name using an SQL query?

rename table name :

RENAME TABLE old_tableName TO new_tableName;

for example:

RENAME TABLE company_name TO company_master;

org.springframework.web.client.HttpClientErrorException: 400 Bad Request

This is what worked for me. Issue is earlier I didn't set Content Type(header) when I used exchange method.

MultiValueMap<String, String> map = new LinkedMultiValueMap<String, String>();
map.add("param1", "123");
map.add("param2", "456");
map.add("param3", "789");
map.add("param4", "123");
map.add("param5", "456");

HttpHeaders headers = new HttpHeaders();

final HttpEntity<MultiValueMap<String, String>> entity = new HttpEntity<MultiValueMap<String, String>>(map ,
JSONObject jsonObject = null;

try {
    RestTemplate restTemplate = new RestTemplate();
    ResponseEntity<String> responseEntity =
            "https://url", HttpMethod.POST, entity,

    if (responseEntity.getStatusCode() == HttpStatus.CREATED) {
        try {
            jsonObject = new JSONObject(responseEntity.getBody());
        } catch (JSONException e) {
            throw new RuntimeException("JSONException occurred");
  } catch (final HttpClientErrorException httpClientErrorException) {
        throw new ExternalCallBadRequestException();
  } catch (HttpServerErrorException httpServerErrorException) {
        throw new ExternalCallServerErrorException(httpServerErrorException);
  } catch (Exception exception) {
        throw new ExternalCallServerErrorException(exception);

ExternalCallBadRequestException and ExternalCallServerErrorException are the custom exceptions here.

Note: Remember HttpClientErrorException is thrown when a 4xx error is received. So if the request you send is wrong either setting header or sending wrong data, you could receive this exception.

String length in bytes in JavaScript

Here is an independent and efficient method to count UTF-8 bytes of a string.

//count UTF-8 bytes of a string_x000D_
function byteLengthOf(s){_x000D_
 //assuming the String is UCS-2(aka UTF-16) encoded_x000D_
 var n=0;_x000D_
 for(var i=0,l=s.length; i<l; i++){_x000D_
  var hi=s.charCodeAt(i);_x000D_
  if(hi<0x0080){ //[0x0000, 0x007F]_x000D_
  }else if(hi<0x0800){ //[0x0080, 0x07FF]_x000D_
  }else if(hi<0xD800){ //[0x0800, 0xD7FF]_x000D_
  }else if(hi<0xDC00){ //[0xD800, 0xDBFF]_x000D_
   var lo=s.charCodeAt(++i);_x000D_
   if(i<l&&lo>=0xDC00&&lo<=0xDFFF){ //followed by [0xDC00, 0xDFFF]_x000D_
    throw new Error("UCS-2 String malformed");_x000D_
  }else if(hi<0xE000){ //[0xDC00, 0xDFFF]_x000D_
   throw new Error("UCS-2 String malformed");_x000D_
  }else{ //[0xE000, 0xFFFF]_x000D_
 return n;_x000D_
var s="\u0000\u007F\u07FF\uD7FF\uDBFF\uDFFF\uFFFF";_x000D_
console.log("expect byteLengthOf(s) to be 14, actually it is %s.",byteLengthOf(s));

Note that the method may throw error if an input string is UCS-2 malformed

How to view the SQL queries issued by JPA?

With Spring Boot simply add: to This will show the query but without the actual parameters (you will see ? instead of each parameter).

-didSelectRowAtIndexPath: not being called

Check if your viewController has following method:

- (BOOL) tableView:(UITableView *)tableView shouldHighlightRowAtIndexPath:(NSIndexPath *)indexPath {
    return NO;

if you return "NO" didSelectRow won't be called

from list of integers, get number closest to a given value

Expanding upon Gustavo Lima's answer. The same thing can be done without creating an entirely new list. The values in the list can be replaced with the differentials as the FOR loop progresses.

def f_ClosestVal(v_List, v_Number):
"""Takes an unsorted LIST of INTs and RETURNS INDEX of value closest to an INT"""
for _index, i in enumerate(v_List):
    v_List[_index] = abs(v_Number - i)
return v_List.index(min(v_List))

myList = [1, 88, 44, 4, 4, -2, 3]
v_Num = 5
print(f_ClosestVal(myList, v_Num)) ## Gives "3," the index of the first "4" in the list.

Use placeholders in yaml


  • YAML version 1.2
  • user wishes to
    • include variable placeholders in YAML
    • have placeholders replaced with computed values, upon yaml.load
    • be able to use placeholders for both YAML mapping keys and values


  • YAML does not natively support variable placeholders.
  • Anchors and Aliases almost provide the desired functionality, but these do not work as variable placeholders that can be inserted into arbitrary regions throughout the YAML text. They must be placed as separate YAML nodes.
  • There are some add-on libraries that support arbitrary variable placeholders, but they are not part of the native YAML specification.


Consider the following example YAML. It is well-formed YAML syntax, however it uses (non-standard) curly-brace placeholders with embedded expressions.

The embedded expressions do not produce the desired result in YAML, because they are not part of the native YAML specification. Nevertheless, they are used in this example only to help illustrate what is available with standard YAML and what is not.

  cust_fname:   "Homer"
  cust_lname:   "Himpson"
  cust_motto:   "I love donuts!"
  cust_email:   [email protected]

  govt_sales_taxrate: 1.15

  prch_unit_label:    "Bacon-Wrapped Fancy Glazed Donut"
  prch_unit_price:    3.00
  prch_unit_quant:    7
  prch_product_cost:  "{{prch_unit_price * prch_unit_quant}}"
  prch_total_cost:    "{{prch_product_cost * govt_sales_taxrate}}"   

  cust_fname:   "{{cust_fname}}"
  cust_lname:   "{{cust_lname}}"
  ship_city:    Houston
  ship_state:   Hexas    

  cust_email:     "{{cust_email}}"
  mail_subject:   Thanks for your DoughNutz order!
  mail_notes: |
    We want the mail_greeting to have all the expected values
    with filled-in placeholders (and not curly-braces).
  mail_greeting: |
    Greetings {{cust_fname}} {{cust_lname}}!
    We love your motto "{{cust_motto}}" and we agree with you!
    Your total purchase price is {{prch_total_cost}}


  • The substitutions marked in GREEN are readily available in standard YAML, using anchors, aliases, and merge keys.

  • The substitutions marked in YELLOW are technically available in standard YAML, but not without a custom type declaration, or some other binding mechanism.

  • The substitutions marked in RED are not available in standard YAML. Yet there are workarounds and alternatives; such as through string formatting or string template engines (such as python's str.format).

Image explaining the different types of variable substitution in YAML


A frequently-requested feature for YAML is the ability to insert arbitrary variable placeholders that support arbitrary cross-references and expressions that relate to the other content in the same (or transcluded) YAML file(s).

YAML supports anchors and aliases, but this feature does not support arbitrary placement of placeholders and expressions anywhere in the YAML text. They only work with YAML nodes.

YAML also supports custom type declarations, however these are less common, and there are security implications if you accept YAML content from potentially untrusted sources.

YAML addon libraries

There are YAML extension libraries, but these are not part of the native YAML spec.


  • Use YAML in conjunction with a template system, such as Jinja2 or Twig
  • Use a YAML extension library
  • Use sprintf or str.format style functionality from the hosting language


  • YTT YAML Templating essentially a fork of YAML with additional features that may be closer to the goal specified in the OP.
  • Jsonnet shares some similarity with YAML, but with additional features that may be closer to the goal specified in the OP.

See also

Here at SO

Outside SO

How do I ignore files in Subversion?

  1. cd ~/.subversion
  2. open config
  3. find the line like 'global-ignores'
  4. set ignore file type like this: global-ignores = *.o *.lo *.la *.al .libs *.so .so.[0-9] *.pyc *.pyo 88 *.rej ~ ## .#* .*.swp .DS_Store node_modules output

ORA-01438: value larger than specified precision allows for this column

One issue I've had, and it was horribly tricky, was that the OCI call to describe a column attributes behaves diffrently depending on Oracle versions. Describing a simple NUMBER column created without any prec or scale returns differenlty on 9i, 1Og and 11g

What's wrong with overridable method calls in constructors?

In the specific case of Wicket: This is the very reason why I asked the Wicket devs to add support for an explicit two phase component initialization process in the framework's lifecycle of constructing a component i.e.

  1. Construction - via constructor
  2. Initialization - via onInitilize (after construction when virtual methods work!)

There was quite an active debate about whether it was necessary or not (it fully is necessary IMHO) as this link demonstrates

The good news is that the excellent devs at Wicket did end up introducing two phase initialization (to make the most aweseome Java UI framework even more awesome!) so with Wicket you can do all your post construction initialization in the onInitialize method that is called by the framework automatically if you override it - at this point in the lifecycle of your component its constructor has completed its work so virtual methods work as expected.

git rebase merge conflict

Note: with Git 2.14.x/2.15 (Q3 2017), the git rebase message in case of conflicts will be clearer.

See commit 5fdacc1 (16 Jul 2017) by William Duclot (williamdclt).
(Merged by Junio C Hamano -- gitster -- in commit 076eeec, 11 Aug 2017)

rebase: make resolve message clearer for inexperienced users


When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort"


Resolve all conflicts manually, 
mark them as resolved with git add/rm <conflicted_files>
then run "git rebase --continue".

You can instead skip this commit: run "git rebase --skip".
To abort and get back to the state before "git rebase", run "git rebase --abort".')

The git UI can be improved by addressing the error messages to those they help: inexperienced and casual git users.
To this intent, it is helpful to make sure the terms used in those messages can be understood by this segment of users, and that they guide them to resolve the problem.

In particular, failure to apply a patch during a git rebase is a common problem that can be very destabilizing for the inexperienced user.
It is important to lead them toward the resolution of the conflict (which is a 3-steps process, thus complex) and reassure them that they can escape a situation they can't handle with "--abort".
This commit answer those two points by detailing the resolution process and by avoiding cryptic git linguo.

How do I return JSON without using a template in Django?

In Django 1.7 this is even easier with the built-in JsonResponse.

# import it
from django.http import JsonResponse

def my_view(request):

    # do something with the your data
    data = {}

    # just return a JsonResponse
    return JsonResponse(data)

Grant Select on a view not base table when base table is in a different database

Create view Schema1.viewName1 as (select * from plaplapla)

Schema1 has all the tables

Create view Schema2.viewName2 as (select * from schema1.viewName1)

schema2 has no tables(only views schema)

In this case you can execute (select * from viewName2) in schema2 , BUT .. If you deleted viewNmae1 from Schema1 , Then ViewName2 will not work..

Amani El Gamal [email protected]

Do you (really) write exception safe code?

EH is good, generally. But C++'s implementation is not very friendly as it's really hard to tell how good your exception catching coverage is. Java for instance makes this easy, the compiler will tend to fail if you don't handle possible exceptions .

How do I install Python 3 on an AWS EC2 instance?

Amazon Linux now supports python36.

python36-pip is not available. So need to follow a different route.

sudo yum install python36 python36-devel python36-libs python36-tools

# If you like to have pip3.6:
curl -O
sudo python3

How to write string literals in python without having to escape them?

There is no such thing. It looks like you want something like "here documents" in Perl and the shells, but Python doesn't have that.

Using raw strings or multiline strings only means that there are fewer things to worry about. If you use a raw string then you still have to work around a terminal "\" and with any string solution you'll have to worry about the closing ", ', ''' or """ if it is included in your data.

That is, there's no way to have the string

 '   ''' """  " \

properly stored in any Python string literal without internal escaping of some sort.

RequestDispatcher.forward() vs HttpServletResponse.sendRedirect()

Technically redirect should be used either if we need to transfer control to different domain or to achieve separation of task.

For example in the payment application we do the PaymentProcess first and then redirect to displayPaymentInfo. If the client refreshes the browser only the displayPaymentInfo will be done again and PaymentProcess will not be repeated. But if we use forward in this scenario, both PaymentProcess and displayPaymentInfo will be re-executed sequentially, which may result in incosistent data.

For other scenarios, forward is efficient to use since as it is faster than sendRedirect

Android eclipse DDMS - Can't access data/data/ on phone to pull files

Event though it's a bit too late to try to answer this I'll leave what worked for me.

Peceps's solution didn't work because the SuperUser app didn't allow "shell" to have root access. So my solution is to directly use another app like RootExplorer and browse the folders from it.

fatal: could not create work tree dir 'kivy'

For other Beginners (like myself) If you are on windows running git as admin also solves the problem.

fast way to copy formatting in excel

You could have simply used Range("x1").value(11) something like below:

Sheets("Output").Range("$A$1:$A$500").value(11) =  Sheets(sheet_).Range("$A$1:$A$500").value(11)

range has default property "Value" plus value can have 3 optional orguments 10,11,12. 11 is what you need to tansfer both value and formats. It doesn't use clipboard so it is faster.- Durgesh

In PHP, how can I add an object element to an array?

Just do:

$object = new stdClass();
$object->name = "My name";
$myArray[] = $object;

You need to create the object first (the new line) and then push it onto the end of the array (the [] line).

You can also do this:

$myArray[] = (object) ['name' => 'My name'];

However I would argue that's not as readable, even if it is more succinct.

How to make a node.js application run permanently?

First install pm2 globally

npm install -g pm2

then start

pm2 start bin/www 

How to access a property of an object (stdClass Object) member/element of an array?

To access an array member you use $array['KEY'];

To access an object member you use $obj->KEY;

To access an object member inside an array of objects:
$array[0] // Get the first object in the array
$array[0]->KEY // then access its key

You may also loop over an array of objects like so:

foreach ($arrayOfObjs as $key => $object) {
    echo $object->object_property;

Think of an array as a collection of things. It's a bag where you can store your stuff and give them a unique id (key) and access them (or take the stuff out of the bag) using that key. I want to keep things simple here, but this bag can contain other bags too :)

Update (this might help someone understand better):

An array contains 'key' and 'value' pairs. Providing a key for an array member is optional and in this case it is automatically assigned a numeric key which starts with 0 and keeps on incrementing by 1 for each additional member. We can retrieve a 'value' from the array by it's 'key'.

So we can define an array in the following ways (with respect to keys):

First method:

$colorPallete = ['red', 'blue', 'green'];

The above array will be assigned numeric keys automatically. So the key assigned to red will be 0, for blue 1 and so on.

Getting values from the above array:

$colorPallete[0]; // will output 'red'
$colorPallete[1]; // will output 'blue'
$colorPallete[2]; // will output 'green'

Second method:

$colorPallete = ['love' => 'red', 'trust' => 'blue', 'envy' => 'green']; // we expliicitely define the keys ourself.

Getting values from the above array:

$colorPallete['love']; // will output 'red'
$colorPallete['trust']; // will output 'blue'
$colorPallete['envy']; // will output 'green'

Difference between .dll and .exe?

The difference is that an EXE has an entry point, a "main" method that will run on execution.

The code within a DLL needs to be called from another application.

Is it possible to set the equivalent of a src attribute of an img tag in CSS?

No you can't set the image src attribute via CSS. The closest you can get is, as you say, background or background-image. I wouldn't recommend doing that anyway as it would be somewhat illogical.

However, there is a CSS3 solution available to you, if the browsers you're targeting are able to use it. Use content:url as described in Pacerier's answer. You can find other, cross-browser solutions in the other answers below.

Setting the default ssh key location

man ssh gives me this options would could be useful.

-i identity_file Selects a file from which the identity (private key) for RSA or DSA authentication is read. The default is ~/.ssh/identity for protocol version 1, and ~/.ssh/id_rsa and ~/.ssh/id_dsa for pro- tocol version 2. Identity files may also be specified on a per- host basis in the configuration file. It is possible to have multiple -i options (and multiple identities specified in config- uration files).

So you could create an alias in your bash config with something like

alias ssh="ssh -i /path/to/private_key"

I haven't looked into a ssh configuration file, but like the -i option this too could be aliased

-F configfile Specifies an alternative per-user configuration file. If a configuration file is given on the command line, the system-wide configuration file (/etc/ssh/ssh_config) will be ignored. The default for the per-user configuration file is ~/.ssh/config.

Python - use list as function parameters

Use an asterisk:


django: TypeError: 'tuple' object is not callable

You're missing comma (,) inbetween:

>>> ((1,2) (2,3))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object is not callable

Put comma:

>>> ((1,2), (2,3))
((1, 2), (2, 3))

Change the color of a checked menu item in a navigation drawer

Here's how you can do it in your Activity's onCreate method:

NavigationView navigationView = findViewById(;
ColorStateList csl = new ColorStateList(
    new int[][] {
        new int[] {-android.R.attr.state_checked}, // unchecked
        new int[] { android.R.attr.state_checked}  // checked
    new int[] {

Create table with jQuery - append

i prefer the most readable and extensible way using jquery.
Also, you can build fully dynamic content on the fly.
Since jquery version 1.4 you can pass attributes to elements which is,
imho, a killer feature. Also the code can be kept cleaner.


        var tablerows = new Array();

        $.each(['result1', 'result2', 'result3'], function( index, value ) {
            tablerows.push('<tr><td>' + value + '</td></tr>');

        var table =  $('<table/>', {
           html:  tablerows

        var div = $('<div/>', {
            id: 'here_table',
            html: table



Addon: passing more than one "html" tag you've to use array notation like: e.g.

var div = $('<div/>', {
            id: 'here_table',
            html: [ div1, div2, table ]

best Rgds.

Intellij JAVA_HOME variable

If you'd like to have your JAVA_HOME recognised by intellij, you can do one of these:

  • Start your intellij from terminal /Applications/IntelliJ IDEA (this will pick your bash env variables)
  • Add login env variable by executing: launchctl setenv JAVA_HOME "/Library/Java/JavaVirtualMachines/jdk1.8.0_60.jdk/Contents/Home"

To directly answer your question, you can add launchctl line in your ~/.bash_profile

As others have answered you can ignore JAVA_HOME by setting up SDK in project structure.

Python Iterate Dictionary by Index

Do this:

for i in dict.keys():

How to move Docker containers between different hosts?

You cannot move a running docker container from one host to another.

You can commit the changes in your container to an image with docker commit, move the image onto a new host, and then start a new container with docker run. This will preserve any data that your application has created inside the container.

Nb: It does not preserve data that is stored inside volumes; you need to move data volumes manually to new host.

NoClassDefFoundError for code in an Java library on Android

I have just figured out something with this error.

Just make sure that the library jar file contains the compiled R class under package and copy all the res in the v7 appcompat support "project" in your ANDROID_SDK_HOME/extras/android/support/v7/appcompat folder.

I use Netbeans with the Android plugin and this solved my issue.

AWS S3 - How to fix 'The request signature we calculated does not match the signature' error?

I don't know if anyone came to this issue while trying to test the outputted URL in browser but if you are using Postman and try to copy the generated url of AWS from the RAW tab, because of escaping backslashes you are going to get the above error.

Use the Pretty tab to copy and paste the url to see if it actually works.

I run into this issue recently and this solution solved my issue. It's for testing purposes to see if you actually retrieve the data through the url.

This answer is a reference to those who try to generate a download, temporary link from AWS or generally generate a URL from AWS to use.

RecyclerView and java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder in Samsung devices

Problem occured for me only when:

I created the Adapter with an empty list. Then I inserted items and called notifyItemRangeInserted.


I solved this by creating the Adapter only after I have the first chunk of data and initialzing it with it right away. The next chunk could then be inserted and notifyItemRangeInserted called with no problem .

Can an Option in a Select tag carry multiple values?

one option is to put multi value with comma seperated


value ="123,1234"

and in the server side separate them

Flask-SQLAlchemy how to delete all rows in a single table


Delete All Records

#for all records

Deleted Single Row

here DB is the object Flask-SQLAlchemy class. It will delete all records from it and if you want to delete specific records then try filter clause in the query. ex.

#for specific value

Delete Single Record by Object

record_obj = db.session.query(Model).filter(

Search and replace a particular string in a file using Perl

A one liner:

perl -pi.back -e 's/<PREF>/ABCD/g;' inputfile

Python: Making a beep noise

I was searching for the same but for Linux shell.

The topic brought me to an answer, -thanks-

Maybe more pythonic manner :

import os
beep = lambda x: os.system("echo -n '\a';sleep 0.2;" * x)

Notes :

  • the sleep value (here 0.2), depends on the length (seconds) of your default beep sound
  • I choosed to use os.system rather then subprocess.Popen for simplicity (it could be bad)
  • the '-n' for echo is to have no more display
  • the last ';' after sleep is necessary for the resulting text sequence (*x)
  • also tested through ssh on an X term

Converting an int to std::string

You can use this function to convert int to std::string after including <sstream>:

#include <sstream>

string IntToString (int a)
    stringstream temp;
    return temp.str();

Android Linear Layout - How to Keep Element At Bottom Of View?

You can also use


for your textview

Read a file line by line with VB.NET

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

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

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

single line comment in HTML

Let's keep it simple. Loved @digitaldreamer 's answer but it might leave the beginners confused. So, I am going to try and simplify it.

The only HTML comment is <!-- --> It can be used as a single line comment or double, it is really up to the developer.

So, an HTML comment starts with <!-- and ends with -->. It is really that simple. You should not use any other format, to avoid any compatibility issue even if the comment format is legit or not.

Parsing jQuery AJAX response

you must parse JSON string to become object

var dataObject = jQuery.parseJSON(data);

so you can call it like:

success: function (data) {
    var dataObject = jQuery.parseJSON(data);
    if (dataObject.success == 1) {
       var insertedGoalId = dataObject.inserted.goal_id;

How can I time a code segment for testing performance with Pythons timeit?

Here is an example of how to time a function using timeit:

import timeit

def time_this(n):
    return [str(i) for i in range(n)]

timeit.timeit(lambda: time_this(n=5000), number=1000)

This will return the time in seconds it took to execute the time_this() function 1000 times.

What's the difference between SoftReference and WeakReference in Java?

In Java; order from strongest to weakest, there are: Strong, Soft, Weak and Phantom

A Strong reference is a normal reference that protects the referred object from collection by GC. i.e. Never garbage collects.

A Soft reference is eligible for collection by garbage collector, but probably won't be collected until its memory is needed. i.e. garbage collects before OutOfMemoryError.

A Weak reference is a reference that does not protect a referenced object from collection by GC. i.e. garbage collects when no Strong or Soft refs.

A Phantom reference is a reference to an object is phantomly referenced after it has been finalized, but before its allocated memory has been reclaimed.


Analogy: Assume a JVM is a kingdom, Object is a king of the kingdom, and GC is an attacker of the kingdom who tries to kill the king(object).

  • When King is Strong, GC can not kill him.
  • When King is Soft, GC attacks him but King rule the kingdom with protection until resource are available.
  • When King is Weak, GC attacks him but rule the kingdom without protection.
  • When king is Phantom, GC already killed him but king is available via his soul.

CORS header 'Access-Control-Allow-Origin' missing

You have to modify your server side code, as given below

public class CorsResponseFilter implements ContainerResponseFilter {
public void filter(ContainerRequestContext requestContext,   ContainerResponseContext responseContext)
    throws IOException {
        responseContext.getHeaders().add("Access-Control-Allow-Methods", "GET, POST, DELETE, PUT");


openCV video saving in python

Try this. It's working for me (Windows 10).

import numpy as np
import cv2

cap = cv2.VideoCapture(0)

# Define the codec and create VideoWriter object
#fourcc =*'DIVX')
#out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
out = cv2.VideoWriter('output.avi', -1, 20.0, (640,480))

    ret, frame =
    if ret==True:
        frame = cv2.flip(frame,0)

        # write the flipped frame

        if cv2.waitKey(1) & 0xFF == ord('q'):

# Release everything if job is finished

How can I manually generate a .pyc file from a .py file

In Python2 you could use:

python -m compileall <pythonic-project-name>

which compiles all .py files to .pyc files in a project which contains packages as well as modules.

In Python3 you could use:

python3 -m compileall <pythonic-project-name>

which compiles all .py files to __pycache__ folders in a project which contains packages as well as modules.

Or with browning from this post:

You can enforce the same layout of .pyc files in the folders as in Python2 by using:

python3 -m compileall -b <pythonic-project-name>

The option -b triggers the output of .pyc files to their legacy-locations (i.e. the same as in Python2).

LaTeX: Prevent line break in a span of text

Use \nolinebreak


The \nolinebreak command prevents LaTeX from breaking the current line at the point of the command. With the optional argument, number, you can convert the \nolinebreak command from a demand to a request. The number must be a number from 0 to 4. The higher the number, the more insistent the request is.


How to prevent vim from creating (and leaving) temporary files?

I have this setup in my Ubuntu .vimrc. I don't see any swap files in my project files.

set undofile
set undolevels=1000         " How many undos
set undoreload=10000        " number of lines to save for undo

set backup                        " enable backups
set swapfile                      " enable swaps
set undodir=$HOME/.vim/tmp/undo     " undo files
set backupdir=$HOME/.vim/tmp/backup " backups
set directory=$HOME/.vim/tmp/swap   " swap files

" Make those folders automatically if they don't already exist.
if !isdirectory(expand(&undodir))
    call mkdir(expand(&undodir), "p")
if !isdirectory(expand(&backupdir))
    call mkdir(expand(&backupdir), "p")
if !isdirectory(expand(&directory))
    call mkdir(expand(&directory), "p")

Adding a directory to PATH in Ubuntu

Actually I would advocate .profile if you need it to work from scripts, and in particular, scripts run by /bin/sh instead of Bash. If this is just for your own private interactive use, .bashrc is fine, though.

Function is not defined - uncaught referenceerror

The problem is that codeAddress() doesn't have enough scope to be callable from the button. You must declare it outside the callback to ready():

function codeAddress() {
    var address = document.getElementById("formatedAddress").value;
    geocoder.geocode( { 'address': address}, function(results, status) {
        if (status == google.maps.GeocoderStatus.OK) {

    // Do stuff here, including _calling_ codeAddress(), but not _defining_ it!

How do I create an Android Spinner as a popup?

If you want to show it as a full screen popup, then you don't even need an xml layout. Here's how do do it in Kotlin.

 val inputArray: Array<String> = arrayOf("Item 1","Item 2")
                val alt_bld =  AlertDialog.Builder(context);
                alt_bld.setSingleChoiceItems(inputArray, -1) { dialog, which ->
                    if(which == 0){
                        //Item 1 Selected
                    else if(which == 1){
                        //Item 2 Selected


                val alert11 = alt_bld.create()

"401 Unauthorized" on a directory

For me the Anonymous User access was fine at the server level, but varied at just one of my "virtual" folders.

Took me quite a bit of foundering about and then some help from a colleague to learn that IIS has "authentication" settings at the virtual folder level too - hopefully this helps someone else with my predicament.

How to dynamically insert a <script> tag via jQuery after page load?

A simpler way is:

$('head').append('<script type="text/javascript" src="your.js"></script>');

You can also use this form to load css.

How to properly make a http web GET request

Servers sometimes compress their responses to save on bandwidth, when this happens, you need to decompress the response before attempting to read it. Fortunately, the .NET framework can do this automatically, however, we have to turn the setting on.

Here's an example of how you could achieve that.

string html = string.Empty;
string url = @"";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.AutomaticDecompression = DecompressionMethods.GZip;

using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
using (Stream stream = response.GetResponseStream())
using (StreamReader reader = new StreamReader(stream))
    html = reader.ReadToEnd();



public string Get(string uri)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;

    using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return reader.ReadToEnd();

GET async

public async Task<string> GetAsync(string uri)
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;

    using(HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return await reader.ReadToEndAsync();

Contains the parameter method in the event you wish to use other HTTP methods such as PUT, DELETE, ETC

public string Post(string uri, string data, string contentType, string method = "POST")
    byte[] dataBytes = Encoding.UTF8.GetBytes(data);

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
    request.ContentLength = dataBytes.Length;
    request.ContentType = contentType;
    request.Method = method;

    using(Stream requestBody = request.GetRequestStream())
        requestBody.Write(dataBytes, 0, dataBytes.Length);

    using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return reader.ReadToEnd();


POST async
Contains the parameter method in the event you wish to use other HTTP methods such as PUT, DELETE, ETC

public async Task<string> PostAsync(string uri, string data, string contentType, string method = "POST")
    byte[] dataBytes = Encoding.UTF8.GetBytes(data);

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
    request.ContentLength = dataBytes.Length;
    request.ContentType = contentType;
    request.Method = method;

    using(Stream requestBody = request.GetRequestStream())
        await requestBody.WriteAsync(dataBytes, 0, dataBytes.Length);

    using(HttpWebResponse response = (HttpWebResponse)await request.GetResponseAsync())
    using(Stream stream = response.GetResponseStream())
    using(StreamReader reader = new StreamReader(stream))
        return await reader.ReadToEndAsync();

Transform char array into String

Visit to solve the problem easily.

This worked for me:

char yyy[6];

String xxx;








postgresql - sql - count of `true` values

In MySQL, you can do this as well:

SELECT count(*) AS total
     , sum(myCol) AS countTrue --yes, you can add TRUEs as TRUE=1 and FALSE=0 !!
FROM yourTable

I think that in Postgres, this works:

SELECT count(*) AS total
     , sum(myCol::int) AS countTrue --convert Boolean to Integer
FROM yourTable

or better (to avoid :: and use standard SQL syntax):

SELECT count(*) AS total
     , sum(CAST(myCol AS int)) AS countTrue --convert Boolean to Integer
FROM yourTable

Float a div in top right corner without overlapping sibling header

If you can change the order of the elements, floating will work.

section {_x000D_
  position: relative;_x000D_
  width: 50%;_x000D_
  border: 1px solid;_x000D_
h1 {_x000D_
  display: inline;_x000D_
div {_x000D_
  float: right;_x000D_
  <h1>some long long long long header, a whole line, 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6</h1>_x000D_

?By placing the div before the h1 and floating it to the right, you get the desired effect.

Lodash remove duplicates from array

You can also use unionBy for 4.0.0 and later, as follows: let uniques = _.unionBy(data, 'id')

How to merge a specific commit in Git

Let's say you want to merge commit e27af03 from branch X to master.

git checkout master
git cherry-pick e27af03
git push

PHP + curl, HTTP POST sample code?

curlPost('', [
    'username' => 'admin',
    'password' => '12345',

function curlPost($url, $data) {
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    $response = curl_exec($ch);
    $error = curl_error($ch);
    if ($error !== '') {
        throw new \Exception($error);

    return $response;

How can I add an element after another element?

First of all, input element shouldn't have a closing tag (from : End tag: forbidden ).

Second thing, you need the after(), not append() function.

Value does not fall within the expected range

I had from a totaly different reason the same notice "Value does not fall within the expected range" from the Visual studio 2008 while trying to use the: Tools -> Windows Embedded Silverlight Tools -> Update Silverlight For Windows Embedded Project.

After spending many ohurs I found out that the problem was that there wasn't a resource file and the update tool looks for the .RC file

Therefor the solution is to add to the resource folder a .RC file and than it works perfectly. I hope it will help someone out there

Disable hover effects on mobile browsers

You can trigger the mouseLeave event whenever you touch an element on touchscreen. Here is a solution for all <a> tags:

function removeHover() {
    var anchors = document.getElementsByTagName('a');
    for(i=0; i<anchors.length; i++) {
        anchors[i].addEventListener('touchstart', function(e){
        }, false);

How to get all key in JSON object (javascript)

var input = {"document":
    {"name":["Harry Potter"],"age":["18"],"gender":["Male"]},
    {"name":["hermione granger"],"age":["18"],"gender":["Female"]},

var keys = [];
for(var i = 0;i<input.document.people.length;i++)
        if(keys.indexOf(key) == -1)

What are the Android SDK build-tools, platform-tools and tools? And which version should be used?

I'll leave the discussion of the difference between Build Tools, Platform Tools, and Tools to others. From a practical standpoint, you only need to know the answer to your second question:

Which version should be used?

Answer: Use the most recent version.

For those using Android Studio with Gradle, the buildToolsVersion has to be set in the build.gradle (Module: app) file.

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"


Where do I get the most recent version number of Build Tools?

Open the Android SDK Manager.

  • In Android Studio go to Tools > Android > SDK Manager > Appearance & Behavior > System Settings > Android SDK
  • Choose the SDK Tools tab.
  • Select Android SDK Build Tools from the list
  • Check Show Package Details.

The last item will show the most recent version.

enter image description here

Make sure it is installed and then write that number as the buildToolsVersion in build.gradle (Module: app).

Can you get the column names from a SqlDataReader?

You sure can.

protected void GetColumNames_DataReader()
  System.Data.SqlClient.SqlConnection SqlCon = new System.Data.SqlClient.SqlConnection("server=localhost;database=northwind;trusted_connection=true");
  System.Data.SqlClient.SqlCommand SqlCmd = new System.Data.SqlClient.SqlCommand("SELECT * FROM Products", SqlCon);


  System.Data.SqlClient.SqlDataReader SqlReader = SqlCmd.ExecuteReader();
  System.Int32 _columncount = SqlReader.FieldCount;

  System.Web.HttpContext.Current.Response.Write("SqlDataReader Columns");
  System.Web.HttpContext.Current.Response.Write(" ");

  for ( System.Int32 iCol = 0; iCol < _columncount; iCol ++ )
    System.Web.HttpContext.Current.Response.Write("Column " + iCol.ToString() + ": ");
    System.Web.HttpContext.Current.Response.Write(SqlReader.GetName( iCol ).ToString());
    System.Web.HttpContext.Current.Response.Write(" ");


This is originally from:

Android 8.0: java.lang.IllegalStateException: Not allowed to start service Intent

i had this problem too

added this library

implementation 'androidx.localbroadcastmanager:localbroadcastmanager:1.0.0'

and reinstalled the app solved this for me

jQuery replace one class with another

You may use this simple plugin:

(function ($) {
    $.fn.replaceClass = function (pFromClass, pToClass) {
        return this.removeClass(pFromClass).addClass(pToClass);




<div class="divFoo colored"></div>


<div class="divFoo blackAndWhite"></div>

Note: you may use various space separated classes.

Hidden features of Windows batch files

TheSoftwareJedi already mentioned the for command, but I'm going to mention it again as it is very powerful.

The following outputs the current date in the format YYYYMMDD, I use this when generating directories for backups.

for /f "tokens=2-4 delims=/- " %a in ('DATE/T') do echo %c%b%a

Can scrapy be used to scrape dynamic content from websites that are using AJAX?

yes, Scrapy can scrap dynamic websites, website that are rendered through javaScript.

There are Two approaches to scrapy these kind of websites.


you can use splash to render Javascript code and then parse the rendered HTML. you can find the doc and project here Scrapy splash, git


As everyone is stating, by monitoring the network calls, yes, you can find the api call that fetch the data and mock that call in your scrapy spider might help you to get desired data.

Trusting all certificates with okHttp

Following method is deprecated

sslSocketFactory(SSLSocketFactory sslSocketFactory)

Consider updating it to

sslSocketFactory(SSLSocketFactory sslSocketFactory, X509TrustManager trustManager)

Jquery UI datepicker. Disable array of Dates

For DD-MM-YY use this code:

var array = ["03-03-2017', '03-10-2017', '03-25-2017"]

    beforeShowDay: function(date){
    var string = jQuery.datepicker.formatDate('dd-mm-yy', date);
    return [ array.indexOf(string) == -1 ]

function highlightDays(date) {
    for (var i = 0; i < dates.length; i++) {
    if (new Date(dates[i]).toString() == date.toString()) {
        return [true, 'highlight'];
return [true, ''];

How to create a link to another PHP page

You can also used like this

<a href="<?php echo 'index.php'; ?>">Index Page</a>
<a href="<?php echo 'page2.php'; ?>">Page 2</a>