Programs & Examples On #Towers of hanoi

A simple puzzle involving moving discs between rods. Commonly used as a programming kata/exercise and frequently set as homework when introducing the concept of recursion.

Tower of Hanoi: Recursive Algorithm

I am trying to get recursion too.

I found a way i think,

i think of it like a chain of steps(the step isnt constant it may change depending on the previous node)

I have to figure out 2 things:

  1. previous node
  2. step kind
  3. after the step what else before call(this is the argument for the next call

example

factorial

1,2,6,24,120 ......... or

1,2*(1),3*(2*1),4*(3*2*1,5*(4*3*2*1)

step=multiple by last node

after the step what i need to get to the next node,abstract 1

ok

function =

n*f(n-1) 

its 2 steps process
from a-->to step--->b

i hoped this help,just think about 2 thniks,not how to get from node to node,but node-->step-->node

node-->step is the body of the function step-->node is the arguments of the other function

bye:) hope i helped

How to prevent sticky hover effects for buttons on touch devices

A solution that has worked for me:

html {
   -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
}

Add this code to your stylesheet.

I wanted to get rid of the grey background that appears on iOS Safari when a link is clicked. But it appears to do more. Now clicking a button (with a :hover pseudoclass!) gets opened right away! I only tested it on an iPad, I don't know if it'll work on other devices.

TypeError: unsupported operand type(s) for -: 'list' and 'list'

The operations needed to be performed, require numpy arrays either created via

np.array()

or can be converted from list to an array via

np.stack()

As in the above mentioned case, 2 lists are inputted as operands it triggers the error.

What is the keyguard in Android?

The lock screen works without keyguard i have tested it. The home button stops working and you can't get to task manager by holding the home key. I wish they didn't develop a new process when it used to be built into system ui or whatever. I don't see the need for the change and extra process

Customizing the template within a Directive

angular.module('formComponents', [])
  .directive('formInput', function() {
    return {
        restrict: 'E',
        compile: function(element, attrs) {
            var type = attrs.type || 'text';
            var required = attrs.hasOwnProperty('required') ? "required='required'" : "";
            var htmlText = '<div class="control-group">' +
                '<label class="control-label" for="' + attrs.formId + '">' + attrs.label + '</label>' +
                    '<div class="controls">' +
                    '<input type="' + type + '" class="input-xlarge" id="' + attrs.formId + '" name="' + attrs.formId + '" ' + required + '>' +
                    '</div>' +
                '</div>';
            element.replaceWith(htmlText);
        }
    };
})

jQuery not working with IE 11

For me the issue turned out to be I was using es6's right arrow functions => as opposed to function ().

Replacing => with function () resolved for me.

I had assumed it was a jQuery issue.

How can I align text in columns using Console.WriteLine?

Just to add to roya's answer. In c# 6.0 you can now use string interpolation:

Console.WriteLine($"{customer[DisplayPos],10}" +
                  $"{salesFigures[DisplayPos],10}" +
                  $"{feePayable[DisplayPos],10}" +
                  $"{seventyPercentValue,10}" +
                  $"{thirtyPercentValue,10}");

This can actually be one line without all the extra dollars, I just think it makes it a bit easier to read like this.

And you could also use a static import on System.Console, allowing you to do this:

using static System.Console;

WriteLine(/* write stuff */);

How to capture Curl output to a file?

A tad bit late, but I think the OP was looking for something like:

curl -K myfile.txt --trace-asci output.txt

Why can't I have "public static const string S = "stuff"; in my Class?

C#'s const is the exact same thing as Java's final, except it's absolutely always static. In my opinion, it's not really necessary for a const variable to be non-static, but if you need to access a const variable non-static-ly, you can do:

class MyClass
{    
    private const int myLowercase_Private_Const_Int = 0;
    public const int MyUppercase_Public_Const_Int = 0;

    /*        
      You can have the `private const int` lowercase 
      and the `public int` Uppercase:
    */
    public int MyLowercase_Private_Const_Int
    {
        get
        {
            return MyClass.myLowercase_Private_Const_Int;
        }
    }  

    /*
      Or you can have the `public const int` uppercase 
      and the `public int` slighly altered
      (i.e. an underscore preceding the name):
    */
    public int _MyUppercase_Public_Const_Int
    {
        get
        {
            return MyClass.MyUppercase_Public_Const_Int;
        }
    } 

    /*
      Or you can have the `public const int` uppercase 
      and get the `public int` with a 'Get' method:
    */
    public int Get_MyUppercase_Public_Const_Int()
    {
        return MyClass.MyUppercase_Public_Const_Int;
    }    
}

Well, now I realize this question was asked 4 years ago, but since I put around 2 hours of work, consisting of trying all sorts of different ways of answering and code formatting, into this answer, I'm still posting it. :)

But, for the record, I still feel kinda silly.

Turning a Comma Separated string into individual rows

As of Feb 2016 - see the TALLY Table Example - very likely to outperform my TVF below, from Feb 2014. Keeping original post below for posterity:


Too much repeated code for my liking in the above examples. And I dislike the performance of CTEs and XML. Also, an explicit Id so that consumers that are order specific can specify an ORDER BY clause.

CREATE FUNCTION dbo.Split
(
    @Line nvarchar(MAX),
    @SplitOn nvarchar(5) = ','
)
RETURNS @RtnValue table
(
    Id INT NOT NULL IDENTITY(1,1) PRIMARY KEY CLUSTERED,
    Data nvarchar(100) NOT NULL
)
AS
BEGIN
    IF @Line IS NULL RETURN

    DECLARE @split_on_len INT = LEN(@SplitOn)
    DECLARE @start_at INT = 1
    DECLARE @end_at INT
    DECLARE @data_len INT

    WHILE 1=1
    BEGIN
        SET @end_at = CHARINDEX(@SplitOn,@Line,@start_at)
        SET @data_len = CASE @end_at WHEN 0 THEN LEN(@Line) ELSE @end_at-@start_at END
        INSERT INTO @RtnValue (data) VALUES( SUBSTRING(@Line,@start_at,@data_len) );
        IF @end_at = 0 BREAK;
        SET @start_at = @end_at + @split_on_len
    END

    RETURN
END

Git Ignores and Maven targets

add following lines in gitignore, from all undesirable files

/target/
*/target/**
**/META-INF/
!.mvn/wrapper/maven-wrapper.jar

### STS ###
.apt_generated
.classpath
.factorypath
.project
.settings
.springBeans
.sts4-cache

### IntelliJ IDEA ###
.idea
*.iws
*.iml
*.ipr

### NetBeans ###
/nbproject/private/
/build/
/nbbuild/
/dist/
/nbdist/
/.nb-gradle/

Use Excel pivot table as data source for another Pivot Table

here is how I've done this before.

  1. put a dummy column "X" off to the right of your source pivot table.
  2. click in that cell and start your pivot table.
  3. once the dialogue box pops up you can edit the data range to include your pivot table.
  4. this may require you to Refresh the source table first and then refresh your secondary pivot table...or do refresh all twice

How to place two divs next to each other?

_x000D_
_x000D_
#wrapper {_x000D_
width: 1200;_x000D_
border: 1px solid black;_x000D_
position: relative;_x000D_
float: left;_x000D_
}_x000D_
#first {_x000D_
width: 300px;_x000D_
border: 1px solid red;_x000D_
position: relative;_x000D_
float: left;_x000D_
}_x000D_
#second {_x000D_
border: 1px solid green;_x000D_
position: relative;_x000D_
float: left;_x000D_
width: 500px;_x000D_
}
_x000D_
<div id="wrapper">_x000D_
    <div id="first">Stack Overflow is for professional and enthusiast programmers, people who write code because they love it.</div>_x000D_
    <div id="second">When you post a new question, other users will almost immediately see it and try to provide good answers. This often happens in a matter of minutes, so be sure to check back frequently when your question is still new for the best response.</div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

How to search JSON data in MySQL?

I think...

Search partial value:

SELECT id FROM table_name WHERE field_name REGEXP '"key_name":"([^"])*key_word([^"])*"';

Search exact word:

SELECT id FROM table_name WHERE field_name RLIKE '"key_name":"[[:<:]]key_word[[:>:]]"';

jquery - disable click

Use off() method after click event is triggered to disable element for the further click.

$('#clickElement').off('click');

AngularJS - Trigger when radio button is selected

There are at least 2 different methods of invoking functions on radio button selection:

1) Using ng-change directive:

<input type="radio" ng-model="value" value="foo" ng-change='newValue(value)'>

and then, in a controller:

$scope.newValue = function(value) {
     console.log(value);
}

Here is the jsFiddle: http://jsfiddle.net/ZPcSe/5/

2) Watching the model for changes. This doesn't require anything special on the input level:

<input type="radio" ng-model="value" value="foo">

but in a controller one would have:

$scope.$watch('value', function(value) {
       console.log(value);
 });

And the jsFiddle: http://jsfiddle.net/vDTRp/2/

Knowing more about your the use case would help to propose an adequate solution.

How to convert the time from AM/PM to 24 hour format in PHP?

$Hour1 = "09:00 am";
$Hour =  date("H:i", strtotime($Hour1));  

'dependencies.dependency.version' is missing error, but version is managed in parent

A couple things I think you could try:

  1. Put the literal value of the version in the child pom

    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>3.2.3.RELEASE</version>
      <scope>runtime</scope>
    </dependency>
    
  2. Clear your .m2 cache normally located C:\Users\user.m2\repository. I would say I do this pretty frequently when I'm working in maven. Especially before committing so that I can be more confident CI will run. You don't have to nuke the folder every time, sometimes just your project packages and the .cache folder are enough.

  3. Add a relativePath tag to your parent pom declaration

    <parent>
      <groupId>com.mycompany.app</groupId>
      <artifactId>my-app</artifactId>
      <version>1</version>
     <relativePath>../parent/pom.xml</relativePath>
    </parent>
    

It looks like you have 8 total errors in your poms. I would try to get some basic compilation running before adding the parent pom and properties.

In c++ what does a tilde "~" before a function name signify?

That would be the destructor(freeing up any dynamic memory)

Pass a PHP string to a JavaScript variable (and escape newlines)

<script>
var myVar = <?php echo json_encode($myVarValue); ?>;
</script>

or

<script>
var myVar = <?= json_encode($myVarValue) ?>;
</script>

Making HTML page zoom by default

Solved it as follows,

in CSS

#my{
zoom: 100%;
}

Now, it loads in 100% zoom by default. Tested it by giving 290% zoom and it loaded by that zoom percentage on default, it's upto the user if he wants to change zoom.

Though this is not the best way to do it, there is another effective solution

Check the page code of stack over flow, even they have buttons and they use un ordered lists to solve this problem.

How to use Redirect in the new react-router-dom of Reactjs

React Router v5 now allows you to simply redirect using history.push() thanks to the useHistory() hook:

import { useHistory } from "react-router"

function HomeButton() {
  let history = useHistory()

  function handleClick() {
    history.push("/home")
  }

  return (
    <button type="button" onClick={handleClick}>
      Go home
    </button>
  )
}

What is an .axd file?

from Google

An .axd file is a HTTP Handler file. There are two types of .axd files.

  1. ScriptResource.axd
  2. WebResource.axd

These are files which are generated at runtime whenever you use ScriptManager in your Web app. This is being generated only once when you deploy it on the server.

Simply put the ScriptResource.AXD contains all of the clientside javascript routines for Ajax. Just because you include a scriptmanager that loads a script file it will never appear as a ScriptResource.AXD - instead it will be merely passed as the .js file you send if you reference a external script file. If you embed it in code then it may merely appear as part of the html as a tag and code but depending if you code according to how the ToolKit handles it - may or may not appear as as a ScriptResource.axd. ScriptResource.axd is only introduced with AJAX and you will never see it elsewhere

And ofcourse it is necessary

Inherit CSS class

CSS "classes" are not OOP "classes". The inheritance works the other way around.
A DOM element can have many classes, either directly or inherited or otherwise associated, which will all be applied in order, overriding earlier defined properties:

<div class="foo bar">
.foo {
    color: blue;
    width: 200px;
}

.bar {
    color: red;
}

The div will be 200px wide and have the color red.

You override properties of DOM elements with different classes, not properties of CSS classes. CSS "classes" are rulesets, the same way ids or tags can be used as rulesets.

Note that the order in which the classes are applied depends on the precedence and specificity of the selector, which is a complex enough topic in itself.

How can I remove a key and its value from an associative array?

Use this function to remove specific arrays of keys without modifying the original array:

function array_except($array, $keys) {
  return array_diff_key($array, array_flip((array) $keys));   
} 

First param pass all array, second param set array of keys to remove.

For example:

$array = [
    'color' => 'red', 
    'age' => '130', 
    'fixed' => true
];
$output = array_except($array, ['color', 'fixed']);
// $output now contains ['age' => '130']

How do I include a Perl module that's in a different directory?

'use lib' can also take a single string value...

#!/usr/bin/perl
use lib '<relative-path>';
use <your lib>;

Maximum request length exceeded.

I had to edit the C:\Windows\System32\inetsrv\config\applicationHost.config file and add <requestLimits maxAllowedContentLength="1073741824" /> to the end of the...

<configuration>
    <system.webServer>
        <security>
            <requestFiltering>

section.

As per This Microsoft Support Article

How do I fix a compilation error for unhandled exception on call to Thread.sleep()?

Thread.sleep can throw an InterruptedException which is a checked exception. All checked exceptions must either be caught and handled or else you must declare that your method can throw it. You need to do this whether or not the exception actually will be thrown. Not declaring a checked exception that your method can throw is a compile error.

You either need to catch it:

try {
    Thread.sleep(1000);
} catch (InterruptedException e) {
    e.printStackTrace();
    // handle the exception...        
    // For example consider calling Thread.currentThread().interrupt(); here.
}

Or declare that your method can throw an InterruptedException:

public static void main(String[]args) throws InterruptedException

Related

set font size in jquery

Not saying this is better, just another way:

$("#elem")[0].style.fontSize="20px";

How to find all duplicate from a List<string>?

I'm assuming each string in your list contains several words, let me know if that's incorrect.

List<string> list = File.RealAllLines("foobar.txt").ToList();

var words = from line in list
            from word in line.Split(new[] { ' ', ';', ',', '.', ':', '(', ')' }, StringSplitOptions.RemoveEmptyEntries)
            select word;

var duplicateWords = from w in words
                     group w by w.ToLower() into g
                     where g.Count() > 1
                     select new
                     {
                         Word = g.Key,
                         Count = g.Count()
                     }

.Net HttpWebRequest.GetResponse() raises exception when http status code 400 (bad request) is returned

This solved it for me:
https://gist.github.com/beccasaurus/929007/a8f820b153a1cfdee3d06a9c0a1d7ebfced8bb77

TL;DR:
Problem:
localhost returns expected content, remote IP alters 400 content to "Bad Request"
Solution:
Adding <httpErrors existingResponse="PassThrough"></httpErrors> to web.config/configuration/system.webServer solved this for me; now all servers (local & remote) return the exact same content (generated by me) regardless of the IP address and/or HTTP code I return.

How do I set the selected item in a comboBox to match my string using C#?

This should do the trick:

Combox1.SelectedIndex = Combox1.FindStringExact("test1")

Regular Expression For Duplicate Words

Since some developers are coming to this page in search of a solution which not only eliminates duplicate consecutive non-whitespace substrings, but triplicates and beyond, I'll show the adapted pattern.

Pattern: /(\b\S+)(?:\s+\1\b)+/ (Pattern Demo)
Replace: $1 (replaces the fullstring match with capture group #1)

This pattern greedily matches a "whole" non-whitespace substring, then requires one or more copies of the matched substring which may be delimited by one or more whitespace characters (space, tab, newline, etc).

Specifically:

  • \b (word boundary) characters are vital to ensure partial words are not matched.
  • The second parenthetical is a non-capturing group, because this variable width substring does not need to be captured -- only matched/absorbed.
  • the + (one or more quantifier) on the non-capturing group is more appropriate than * because * will "bother" the regex engine to capture and replace singleton occurrences -- this is wasteful pattern design.

*note if you are dealing with sentences or input strings with punctuation, then the pattern will need to be further refined.

How to put data containing double-quotes in string variable?

You can escape (this is how this principle is called) the double quotes by prefixing them with another double quote. You can put them in a string as follows:

Dim MyVar as string = "some text ""hello"" "

This will give the MyVar variable a value of some text "hello".

How to add values in a variable in Unix shell scripting?

You can do this as well. Can be faster for quick calculations:

echo $[2+2]

Get String in YYYYMMDD format from JS date object?

_x000D_
_x000D_
var someDate = new Date();_x000D_
var dateFormated = someDate.toISOString().substr(0,10);_x000D_
_x000D_
console.log(dateFormated);
_x000D_
_x000D_
_x000D_

Post parameter is always null

I'm a little late to the party, but anyone who stumbles across a NULL value passed when using a controller simply add "=" to the front of your POST request.

The controller also passed a NULL value when I used the application/json Content-Type. Note the "application/x-www-form-urlencoded" Content-Type below. The return type from the API however is "application/json".

 public static string HttpPostRequest(string url, Dictionary<string, string> postParameters)
    {
        string postData = "=";

        foreach (string key in postParameters.Keys)
        {
            postData += HttpUtility.UrlEncode(key) + "="
                  + HttpUtility.UrlEncode(postParameters[key]) + ",";
        }

        HttpWebRequest myHttpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
        myHttpWebRequest.Method = "POST";

        byte[] data = System.Text.Encoding.ASCII.GetBytes(postData);

        myHttpWebRequest.ContentType = "application/x-www-form-urlencoded";
        myHttpWebRequest.ContentLength = data.Length;

        Stream requestStream = myHttpWebRequest.GetRequestStream();
        requestStream.Write(data, 0, data.Length);
        requestStream.Close();

        HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse();

        Stream responseStream = myHttpWebResponse.GetResponseStream();

        StreamReader myStreamReader = new StreamReader(responseStream, System.Text.Encoding.Default);

        string pageContent = myStreamReader.ReadToEnd();

        myStreamReader.Close();
        responseStream.Close();

        myHttpWebResponse.Close();

        return pageContent;
    }

How to get the mysql table columns data type?

The query below returns a list of information about each field, including the MySQL field type. Here is an example:

SHOW FIELDS FROM tablename
/* returns "Field", "Type", "Null", "Key", "Default", "Extras" */

See this manual page.

How to transfer some data to another Fragment?

getArguments() is returning null because "Its doesn't get anything"

Try this code to handle this situation

if(getArguments()!=null)
{
int myInt = getArguments().getInt(key, defaultValue);
}

Why does one use dependency injection?

I think a lot of times people get confused about the difference between dependency injection and a dependency injection framework (or a container as it is often called).

Dependency injection is a very simple concept. Instead of this code:

public class A {
  private B b;

  public A() {
    this.b = new B(); // A *depends on* B
  }

  public void DoSomeStuff() {
    // Do something with B here
  }
}

public static void Main(string[] args) {
  A a = new A();
  a.DoSomeStuff();
}

you write code like this:

public class A {
  private B b;

  public A(B b) { // A now takes its dependencies as arguments
    this.b = b; // look ma, no "new"!
  }

  public void DoSomeStuff() {
    // Do something with B here
  }
}

public static void Main(string[] args) {
  B b = new B(); // B is constructed here instead
  A a = new A(b);
  a.DoSomeStuff();
}

And that's it. Seriously. This gives you a ton of advantages. Two important ones are the ability to control functionality from a central place (the Main() function) instead of spreading it throughout your program, and the ability to more easily test each class in isolation (because you can pass mocks or other faked objects into its constructor instead of a real value).

The drawback, of course, is that you now have one mega-function that knows about all the classes used by your program. That's what DI frameworks can help with. But if you're having trouble understanding why this approach is valuable, I'd recommend starting with manual dependency injection first, so you can better appreciate what the various frameworks out there can do for you.

Calculating how many days are between two dates in DB2?

Wouldn't it just be:

SELECT CURRENT_DATE - CHDLM FROM CHCART00 WHERE CHSTAT = '05';

That should return the number of days between the two dates, if I understand how date arithmetic works in DB2 correctly.

If CHDLM isn't a date you'll have to convert it to one. According to IBM the DATE() function would not be sufficient for the yyyymmdd format, but it would work if you can format like this: yyyy-mm-dd.

How do files get into the External Dependencies in Visual Studio C++?

The External Dependencies folder is populated by IntelliSense: the contents of the folder do not affect the build at all (you can in fact disable the folder in the UI).

You need to actually include the header (using a #include directive) to use it. Depending on what that header is, you may also need to add its containing folder to the "Additional Include Directories" property and you may need to add additional libraries and library folders to the linker options; you can set all of these in the project properties (right click the project, select Properties). You should compare the properties with those of the project that does build to determine what you need to add.

Why use the 'ref' keyword when passing an object?

By using the ref keyword with reference types you are effectively passing a reference to the reference. In many ways it's the same as using the out keyword but with the minor difference that there's no guarantee that the method will actually assign anything to the ref'ed parameter.

setContentView(R.layout.main); error

if you have multiple packages with different classes then it will be confusing: try this:

import package_name_from_AndroidManifest.R;

Create an Oracle function that returns a table

  CREATE OR REPLACE PACKAGE BODY TEST AS 

   FUNCTION GET_UPS(
   TIMESPAN_IN IN VARCHAR2 DEFAULT 'MONTLHY',
   STARTING_DATE_IN DATE,
   ENDING_DATE_IN DATE
   )RETURN MEASURE_TABLE IS

    T MEASURE_TABLE;

 BEGIN

    **SELECT   MEASURE_RECORD(L4_ID , L6_ID ,L8_ID ,YEAR ,
             PERIOD,VALUE )  BULK COLLECT  INTO    T
    FROM    ...**

  ;

   RETURN T;

   END GET_UPS;

END TEST;

Rename a column in MySQL

Syntax: ALTER TABLE table_name CHANGE old_column_name new_column_name datatype;

If table name is Student and column name is Name. Then, if you want to change Name to First_Name

ALTER TABLE Student CHANGE Name First_Name varchar(20);

How to show only next line after the matched one?

If that next lines never contain 'blah', you can filter them with:

grep -A1 blah logfile | grep -v blah

The use of cat logfile | ... is not needed.

How to find minimum value from vector?

#include <iostream>
int main()
{
    int v[100] = {5,14,2,4,6};
    int n = 5;
    int mic = v[0];
    for(int i = 0; i != n; ++i)
    {
        if(v[i] < mic)
        mic = v[i];
    }
    std:cout << mic << std::endl;;
}

How can I count text lines inside an DOM element? Can I?

I am convinced that it is impossible now. It was, though.

IE7’s implementation of getClientRects did exactly what I want. Open this page in IE8, try refreshing it varying window width, and see how number of lines in the first element changes accordingly. Here’s the key lines of the javascript from that page:

var rects = elementList[i].getClientRects();
var p = document.createElement('p');
p.appendChild(document.createTextNode('\'' + elementList[i].tagName + '\' element has ' + rects.length + ' line(s).'));

Unfortunately for me, Firefox always returns one client rectangle per element, and IE8 does the same now. (Martin Honnen’s page works today because IE renders it in IE compat view; press F12 in IE8 to play with different modes.)

This is sad. It looks like once again Firefox’s literal but worthless implementation of the spec won over Microsoft’s useful one. Or do I miss a situation where new getClientRects may help a developer?

java, get set methods

your panel class don't have a constructor that accepts a string

try change

RLS_strid_panel p = new RLS_strid_panel(namn1);

to

RLS_strid_panel p = new RLS_strid_panel();
p.setName1(name1);

How to print star pattern in JavaScript in a very simple manner?

It's very simple, Try this code as below:

for(var i = 1; i <= 5; i++) {

      for(var j = 1; j<= i; j++) {

        document.write("*");  

      }

      document.write("<br/>");
}

Clear the cache in JavaScript

Maybe "clearing cache" is not as easy as it should be. Instead of clearing cache on my browsers, I realized that "touching" the file will actually change the date of the source file cached on the server (Tested on Edge, Chrome and Firefox) and most browsers will automatically download the most current fresh copy of whats on your server (code, graphics any multimedia too). I suggest you just copy the most current scripts on the server and "do the touch thing" solution before your program runs, so it will change the date of all your problem files to a most current date and time, then it downloads a fresh copy to your browser:

<?php
    touch('/www/control/file1.js');
    touch('/www/control/file2.js');
    touch('/www/control/file2.js');
?>

...the rest of your program...

It took me some time to resolve this issue (as many browsers act differently to different commands, but they all check time of files and compare to your downloaded copy in your browser, if different date and time, will do the refresh), If you can't go the supposed right way, there is always another usable and better solution to it. Best Regards and happy camping.

How does "304 Not Modified" work exactly?

When the browser puts something in its cache, it also stores the Last-Modified or ETag header from the server.

The browser then sends a request with the If-Modified-Since or If-None-Match header, telling the server to send a 304 if the content still has that date or ETag.

The server needs some way of calculating a date-modified or ETag for each version of each resource; this typically comes from the filesystem or a separate database column.

What is the difference between max-device-width and max-width for mobile web?

the difference is that max-device-width is all screen's width and max-width means the space used by the browser to show the pages. But another important difference is the support of android browsers, in fact if u're going to use max-device-width this will work only in Opera, instead I'm sure that max-width will work for every kind of mobile browser (I had test it in Chrome, firefox and opera for ANDROID).

How Can I Truncate A String In jQuery?

Instead of using jQuery, use css property text-overflow:ellipsis. It will automatically truncate the string.

.truncated { display:inline-block; 
             max-width:100px; 
             overflow:hidden; 
             text-overflow:ellipsis; 
             white-space:nowrap; 
           }

How to Alter Constraint

No. We cannot alter the constraint, only thing we can do is drop and recreate it

ALTER TABLE [TABLENAME] DROP CONSTRAINT [CONSTRAINTNAME]

Foreign Key Constraint

Alter Table Table1 Add Constraint [CONSTRAINTNAME] Foreign Key (Column) References Table2 (Column) On Update Cascade On Delete Cascade

Primary Key constraint

Alter Table Table add constraint [Primary Key] Primary key(Column1,Column2,.....)

How should strace be used?

strace lists all system calls done by the process it's applied to. If you don't know what system calls mean, you won't be able to get much mileage from it.

Nevertheless, if your problem involves files or paths or environment values, running strace on the problematic program and redirecting the output to a file and then grepping that file for your path/file/env string may help you see what your program is actually attempting to do, as distinct from what you expected it to.

How to read a file byte by byte in Python and how to print a bytelist as a binary?

The code you've shown will read 8 bytes. You could use

with open(filename, 'rb') as f:
   while 1:
      byte_s = f.read(1)
      if not byte_s:
         break
      byte = byte_s[0]
      ...

How to split a delimited string in Ruby and convert it to an array?

"12345".each_char.map(&:to_i)

each_char does basically the same as split(''): It splits a string into an array of its characters.

hmmm, I just realize now that in the original question the string contains commas, so my answer is not really helpful ;-(..

How do you reverse a string in place in C or C++?

In case you are using GLib, it has two functions for that, g_strreverse() and g_utf8_strreverse()

How to undo "git commit --amend" done instead of "git commit"

  1. Checkout to temporary branch with last commit

    git branch temp HEAD@{1}

  2. Reset last commit

    git reset temp

  3. Now, you'll have all files your commit as well as previous commit. Check status of all the files.

    git status

  4. Reset your commit files from git stage.

    git reset myfile1.js (so on)

  5. Reattach this commit

    git commit -C HEAD@{1}

  6. Add and commit your files to new commit.

Counting how many times a certain char appears in a string before any other char appears

public static int GetHowManyTimeOccurenceCharInString(string text, char c)
{
    int count = 0;
    foreach(char ch in text)
    {
        if(ch.Equals(c))
        {
            count++;
        }

    }
    return count;
}

How to get the full path of the file from a file input

You cannot do so - the browser will not allow this because of security concerns. Although there are workarounds, the fact is that you shouldn't count on this working. The following Stack Overflow questions are relevant here:

In addition to these, the new HTML5 specification states that browsers will need to feed a Windows compatible fakepath into the input type="file" field, ostensibly for backward compatibility reasons.

So trying to obtain the path is worse then useless in newer browsers - you'll actually get a fake one instead.

AppStore - App status is ready for sale, but not in app store

After 48 hours of the still not being updated I removed the app from sale on Pricing and Availability.

Then I waited 1 hour.

Then I ticked All Territories Selected again.

After the app came available for download again the version number was updated.

Offline Speech Recognition In Android (JellyBean)

I successfully implemented my Speech-Service with offline capabilities by using onPartialResults when offline and onResults when online.

How many values can be represented with n bits?

There's an easier way to think about this. Start with 1 bit. This can obviously represent 2 values (0 or 1). What happens when we add a bit? We can now represent twice as many values: the values we could represent before with a 0 appended and the values we could represent before with a 1 appended.

So the the number of values we can represent with n bits is just 2^n (2 to the power n)

Change output format for MySQL command line results to CSV

I wound up writing my own command-line tool to take care of this. It's similar to cut, except it knows what to do with quoted fields, etc. This tool, paired with @Jimothy's answer, allows me to get a headerless CSV from a remote MySQL server I have no filesystem access to onto my local machine with this command:

$ mysql -N -e "select people, places from things" | csvm -i '\t' -o ','
Bill,"Raleigh, NC"

csvmaster on github

Using Selenium Web Driver to retrieve value of a HTML input

As was mentioned before, you could do something like that

public String getVal(WebElement webElement) {
    JavascriptExecutor e = (JavascriptExecutor) driver;
    return (String) e.executeScript(String.format("return $('#%s').val();", webElement.getAttribute("id")));
}

But as you can see, your element must have an id attribute, and also, jquery on your page.

Adding a public key to ~/.ssh/authorized_keys does not log me in automatically

Issue these on the command line:

chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys

After you do this, make sure your directory is like this:

drwx------ 2 lab lab 4.0K Mar 13 08:33 .
drwx------ 8 lab lab 4.0K Mar 13 08:07 ..
-rw------- 1 lab lab  436 Mar 13 08:33 authorized_keys
-rw------- 1 lab lab 1.7K Mar 13 07:35 id_rsa
-rw-r--r-- 1 lab lab  413 Mar 13 07:35 id_rsa.pub

How to set width of a p:column in a p:dataTable in PrimeFaces 3.0?

I don't know what browser you're using, but according to w3schools.com, nth-child and nth-last-child do now work on MSIE 8. I don't know about 9. http://www.w3schools.com/cssref/pr_border-style.asp will give you more info.

Set padding for UITextField with UITextBorderStyleNone

I found it far easier to use a non-editable UITextView and set the contentOffset

uiTextView.contentOffset = CGPointMake(8, 7);

Breaking up long strings on multiple lines in Ruby without stripping newlines

I had this problem when I try to write a very long url, the following works.

image_url = %w(
    http://minio.127.0.0.1.xip.io:9000/
    bucket29/docs/b7cfab0e-0119-452c-b262-1b78e3fccf38/
    28ed3774-b234-4de2-9a11-7d657707f79c?
    X-Amz-Algorithm=AWS4-HMAC-SHA256&
    X-Amz-Credential=ABABABABABABABABA
    %2Fus-east-1%2Fs3%2Faws4_request&
    X-Amz-Date=20170702T000940Z&
    X-Amz-Expires=3600&X-Amz-SignedHeaders=host&
    X-Amz-Signature=ABABABABABABABABABABAB
    ABABABABABABABABABABABABABABABABABABA
).join

Note, there must not be any newlines, white spaces when the url string is formed. If you want newlines, then use HEREDOC.

Here you have indentation for readability, ease of modification, without the fiddly quotes and backslashes on every line. The cost of joining the strings should be negligible.

How to perform a sum of an int[] array

int sum = 0;
for(int i = 0; i < A.length; i++){
  sum += A[i];
}

How can I easily add storage to a VirtualBox machine with XP installed?

For Windows users there's an additional user friendly option: CloneVDI Tool by mpack. It's a GUI front-end to VBoxManage that makes things a little easier to work with.

http://forums.virtualbox.org/viewtopic.php?f=6&t=22422

As Alexander M. mentioned, you'll still have to use GParted, Partition Magic or a similar partition editor to grow your partition to the newly allocated physical drive. To do this just download the GParted iso, mount it as a bootable drive in the VirtualBox and boot from it.

http://gparted.sourceforge.net/download.php

TypeError: not all arguments converted during string formatting python

For me, This error was caused when I was attempting to pass in a tuple into the string format method.

I found the solution from this question/answer

Copying and pasting the correct answer from the link (NOT MY WORK):

>>> thetuple = (1, 2, 3)
>>> print "this is a tuple: %s" % (thetuple,)
this is a tuple: (1, 2, 3)

Making a singleton tuple with the tuple of interest as the only item, i.e. the (thetuple,) part, is the key bit here.

What is the difference between lower bound and tight bound?

If you have something that's O(f(n)) that means there's are k, g(n) such that f(n)k g(n).

If you have something that's Ω(f(n)) that means there's are k, g(n) such that f(n)k g(n).

And if you have a something with O(f(n)) and Ω(f(n)), then it's Θ(f(n).

The Wikipedia article is decent, if a little dense.

How to kill a process running on particular port in Linux?

sudo apt-get install psmisc (or sudo yum install psmisc)
sudo fuser 80/tcp

Result: 80/tcp: 1858 1867 1868 1869 1871

Kill process one by one

kill -9 1858

Drop a temporary table if it exists

What you asked for is:

IF OBJECT_ID('tempdb..##CLIENTS_KEYWORD') IS NOT NULL
    BEGIN
       DROP TABLE ##CLIENTS_KEYWORD

       CREATE TABLE ##CLIENTS_KEYWORD(client_id int)

    END
ELSE
   CREATE TABLE ##CLIENTS_KEYWORD(client_id int) 

IF OBJECT_ID('tempdb..##TEMP_CLIENTS_KEYWORD') IS NOT NULL
    BEGIN
       DROP TABLE ##TEMP_CLIENTS_KEYWORD

       CREATE TABLE ##TEMP_CLIENTS_KEYWORD(client_id int)

    END
ELSE
   CREATE TABLE ##TEMP_CLIENTS_KEYWORD(client_id int) 

Since you're always going to create the table, regardless of whether the table is deleted or not; a slightly optimised solution is:

IF OBJECT_ID('tempdb..##CLIENTS_KEYWORD') IS NOT NULL
   DROP TABLE ##CLIENTS_KEYWORD

CREATE TABLE ##CLIENTS_KEYWORD(client_id int) 

IF OBJECT_ID('tempdb..##TEMP_CLIENTS_KEYWORD') IS NOT NULL
   DROP TABLE ##TEMP_CLIENTS_KEYWORD

CREATE TABLE ##TEMP_CLIENTS_KEYWORD(client_id int) 

How to use npm with ASP.NET Core

I give you two answers. npm combined with other tools is powerful but requires some work to setup. If you just want to download some libraries, you might want to use Library Manager instead (released in Visual Studio 15.8).

NPM (Advanced)

First add package.json in the root of you project. Add the following content:

{
  "version": "1.0.0",
  "name": "asp.net",
  "private": true,
  "devDependencies": {
    "gulp": "3.9.1",
    "del": "3.0.0"
  },
  "dependencies": {
    "jquery": "3.3.1",
    "jquery-validation": "1.17.0",
    "jquery-validation-unobtrusive": "3.2.10",
    "bootstrap": "3.3.7"
  }
}

This will make NPM download Bootstrap, JQuery and other libraries that is used in a new asp.net core project to a folder named node_modules. Next step is to copy the files to an appropriate place. To do this we will use gulp, which also was downloaded by NPM. Then add a new file in the root of you project named gulpfile.js. Add the following content:

/// <binding AfterBuild='default' Clean='clean' />
/*
This file is the main entry point for defining Gulp tasks and using Gulp plugins.
Click here to learn more. http://go.microsoft.com/fwlink/?LinkId=518007
*/

var gulp = require('gulp');
var del = require('del');

var nodeRoot = './node_modules/';
var targetPath = './wwwroot/lib/';

gulp.task('clean', function () {
    return del([targetPath + '/**/*']);
});

gulp.task('default', function () {
    gulp.src(nodeRoot + "bootstrap/dist/js/*").pipe(gulp.dest(targetPath + "/bootstrap/dist/js"));
    gulp.src(nodeRoot + "bootstrap/dist/css/*").pipe(gulp.dest(targetPath + "/bootstrap/dist/css"));
    gulp.src(nodeRoot + "bootstrap/dist/fonts/*").pipe(gulp.dest(targetPath + "/bootstrap/dist/fonts"));

    gulp.src(nodeRoot + "jquery/dist/jquery.js").pipe(gulp.dest(targetPath + "/jquery/dist"));
    gulp.src(nodeRoot + "jquery/dist/jquery.min.js").pipe(gulp.dest(targetPath + "/jquery/dist"));
    gulp.src(nodeRoot + "jquery/dist/jquery.min.map").pipe(gulp.dest(targetPath + "/jquery/dist"));

    gulp.src(nodeRoot + "jquery-validation/dist/*.js").pipe(gulp.dest(targetPath + "/jquery-validation/dist"));

    gulp.src(nodeRoot + "jquery-validation-unobtrusive/dist/*.js").pipe(gulp.dest(targetPath + "/jquery-validation-unobtrusive"));
});

This file contains a JavaScript code that is executed when the project is build and cleaned. It’s will copy all necessary files to lib2 (not lib – you can easily change this). I have used the same structure as in a new project, but it’s easy to change files to a different location. If you move the files, make sure you also update _Layout.cshtml. Note that all files in the lib2-directory will be removed when the project is cleaned.

If you right click on gulpfile.js, you can select Task Runner Explorer. From here you can run gulp manually to copy or clean files.

Gulp could also be useful for other tasks like minify JavaScript and CSS-files:

https://docs.microsoft.com/en-us/aspnet/core/client-side/using-gulp?view=aspnetcore-2.1

Library Manager (Simple)

Right click on you project and select Manage client side-libraries. The file libman.json is now open. In this file you specify which library and files to use and where they should be stored locally. Really simple! The following file copies the default libraries that is used when creating a new ASP.NET Core 2.1 project:

{
  "version": "1.0",
  "defaultProvider": "cdnjs",
  "libraries": [
    {
      "library": "[email protected]",
      "files": [ "jquery.js", "jquery.min.map", "jquery.min.js" ],
      "destination": "wwwroot/lib/jquery/dist/"
    },
    {
      "library": "[email protected]",
      "files": [ "additional-methods.js", "additional-methods.min.js", "jquery.validate.js", "jquery.validate.min.js" ],
      "destination": "wwwroot/lib/jquery-validation/dist/"
    },
    {
      "library": "[email protected]",
      "files": [ "jquery.validate.unobtrusive.js", "jquery.validate.unobtrusive.min.js" ],
      "destination": "wwwroot/lib/jquery-validation-unobtrusive/"
    },
    {
      "library": "[email protected]",
      "files": [
        "css/bootstrap.css",
        "css/bootstrap.css.map",
        "css/bootstrap.min.css",
        "css/bootstrap.min.css.map",
        "css/bootstrap-theme.css",
        "css/bootstrap-theme.css.map",
        "css/bootstrap-theme.min.css",
        "css/bootstrap-theme.min.css.map",
        "fonts/glyphicons-halflings-regular.eot",
        "fonts/glyphicons-halflings-regular.svg",
        "fonts/glyphicons-halflings-regular.ttf",
        "fonts/glyphicons-halflings-regular.woff",
        "fonts/glyphicons-halflings-regular.woff2",
        "js/bootstrap.js",
        "js/bootstrap.min.js",
        "js/npm.js"
      ],
      "destination": "wwwroot/lib/bootstrap/dist"
    },
    {
      "library": "[email protected]",
      "files": [ "list.js", "list.min.js" ],
      "destination": "wwwroot/lib/listjs"
    }
  ]
}

If you move the files, make sure you also update _Layout.cshtml.

ImportError: No module named sqlalchemy

try this:

from flask.ext.sqlalchemy import SQLAlchemy

NSURLErrorDomain error codes description

IN SWIFT 3. Here are the NSURLErrorDomain error codes description in a Swift 3 enum: (copied from answer above and converted what i can).

enum NSURLError: Int {
    case unknown = -1
    case cancelled = -999
    case badURL = -1000
    case timedOut = -1001
    case unsupportedURL = -1002
    case cannotFindHost = -1003
    case cannotConnectToHost = -1004
    case connectionLost = -1005
    case lookupFailed = -1006
    case HTTPTooManyRedirects = -1007
    case resourceUnavailable = -1008
    case notConnectedToInternet = -1009
    case redirectToNonExistentLocation = -1010
    case badServerResponse = -1011
    case userCancelledAuthentication = -1012
    case userAuthenticationRequired = -1013
    case zeroByteResource = -1014
    case cannotDecodeRawData = -1015
    case cannotDecodeContentData = -1016
    case cannotParseResponse = -1017
    //case NSURLErrorAppTransportSecurityRequiresSecureConnection NS_ENUM_AVAILABLE(10_11, 9_0) = -1022
    case fileDoesNotExist = -1100
    case fileIsDirectory = -1101
    case noPermissionsToReadFile = -1102
    //case NSURLErrorDataLengthExceedsMaximum NS_ENUM_AVAILABLE(10_5, 2_0) =   -1103

    // SSL errors
    case secureConnectionFailed = -1200
    case serverCertificateHasBadDate = -1201
    case serverCertificateUntrusted = -1202
    case serverCertificateHasUnknownRoot = -1203
    case serverCertificateNotYetValid = -1204
    case clientCertificateRejected = -1205
    case clientCertificateRequired = -1206
    case cannotLoadFromNetwork = -2000

    // Download and file I/O errors
    case cannotCreateFile = -3000
    case cannotOpenFile = -3001
    case cannotCloseFile = -3002
    case cannotWriteToFile = -3003
    case cannotRemoveFile = -3004
    case cannotMoveFile = -3005
    case downloadDecodingFailedMidStream = -3006
    case downloadDecodingFailedToComplete = -3007

    /*
     case NSURLErrorInternationalRoamingOff NS_ENUM_AVAILABLE(10_7, 3_0) =         -1018
     case NSURLErrorCallIsActive NS_ENUM_AVAILABLE(10_7, 3_0) =                    -1019
     case NSURLErrorDataNotAllowed NS_ENUM_AVAILABLE(10_7, 3_0) =                  -1020
     case NSURLErrorRequestBodyStreamExhausted NS_ENUM_AVAILABLE(10_7, 3_0) =      -1021

     case NSURLErrorBackgroundSessionRequiresSharedContainer NS_ENUM_AVAILABLE(10_10, 8_0) = -995
     case NSURLErrorBackgroundSessionInUseByAnotherProcess NS_ENUM_AVAILABLE(10_10, 8_0) = -996
     case NSURLErrorBackgroundSessionWasDisconnected NS_ENUM_AVAILABLE(10_10, 8_0)= -997
     */
}

Direct link to URLError.Code in the Swift github repository, which contains the up to date list of error codes being used (github link).

How to store NULL values in datetime fields in MySQL?

It depends on how you declare your table. NULL would not be allowed in:

create table MyTable (col1 datetime NOT NULL);

But it would be allowed in:

create table MyTable (col1 datetime NULL);

The second is the default, so someone must've actively decided that the column should not be nullable.

Python how to exit main function

use sys module

import sys
sys.exit()

Intellij JAVA_HOME variable

The problem is your "Project SDK" is none! Add a "Project SDK" by clicking "New ..." and choose the path of JDK. And then it should be OK.

OS specific instructions in CMAKE: How to?

Use

if (WIN32)
    #do something
endif (WIN32)

or

if (UNIX)
    #do something
endif (UNIX)

or

if (MSVC)
    #do something
endif (MSVC)

or similar

see CMake Useful Variables and CMake Checking Platform

What is the difference between "screen" and "only screen" in media queries?

To style for many smartphones with smaller screens, you could write:

@media screen and (max-width:480px) { … } 

To block older browsers from seeing an iPhone or Android phone style sheet, you could write:

@media only screen and (max-width: 480px;) { … } 

Read this article for more http://webdesign.about.com/od/css3/a/css3-media-queries.htm

Import Maven dependencies in IntelliJ IDEA

What helped me:

Navigage: Settings | Build, Execution, Deployment | Maven

Specify "Maven home directory" - the place you installed the maven

Difference between object and class in Scala

In scala, there is no static concept. So scala creates a singleton object to provide entry point for your program execution. If you don't create singleton object, your code will compile successfully but will not produce any output. Methods declared inside Singleton Object are accessible globally. A singleton object can extend classes and traits.

Scala Singleton Object Example

object Singleton{  
    def main(args:Array[String]){  
        SingletonObject.hello()         // No need to create object.  
    }  
}  


object SingletonObject{  
    def hello(){  
        println("Hello, This is Singleton Object")  
    }  
}  

Output:

Hello, This is Singleton Object

In scala, when you have a class with same name as singleton object, it is called companion class and the singleton object is called companion object.

The companion class and its companion object both must be defined in the same source file.

Scala Companion Object Example

class ComapanionClass{  
    def hello(){  
        println("Hello, this is Companion Class.")  
    }  
}  
object CompanoinObject{  
    def main(args:Array[String]){  
        new ComapanionClass().hello()  
        println("And this is Companion Object.")  
    }  
}  

Output:

Hello, this is Companion Class.
And this is Companion Object.

In scala, a class can contain:

1. Data member

2. Member method

3. Constructor Block

4. Nested class

5. Super class information etc.

You must initialize all instance variables in the class. There is no default scope. If you don't specify access scope, it is public. There must be an object in which main method is defined. It provides starting point for your program. Here, we have created an example of class.

Scala Sample Example of Class

class Student{  
    var id:Int = 0;                         // All fields must be initialized  
    var name:String = null;  
}  
object MainObject{  
    def main(args:Array[String]){  
        var s = new Student()               // Creating an object  
        println(s.id+" "+s.name);  
    }  
} 

I am sorry, I am too late but I hope it will help you.

How to query as GROUP BY in django?

Django does not support free group by queries. I learned it in the very bad way. ORM is not designed to support stuff like what you want to do, without using custom SQL. You are limited to:

  • RAW sql (i.e. MyModel.objects.raw())
  • cr.execute sentences (and a hand-made parsing of the result).
  • .annotate() (the group by sentences are performed in the child model for .annotate(), in examples like aggregating lines_count=Count('lines'))).

Over a queryset qs you can call qs.query.group_by = ['field1', 'field2', ...] but it is risky if you don't know what query are you editing and have no guarantee that it will work and not break internals of the QuerySet object. Besides, it is an internal (undocumented) API you should not access directly without risking the code not being anymore compatible with future Django versions.

How do I disable text selection with CSS or JavaScript?

<div 
 style="-moz-user-select: none; -webkit-user-select: none; -ms-user-select:none; user-select:none;-o-user-select:none;" 
 unselectable="on"
 onselectstart="return false;" 
 onmousedown="return false;">
    Blabla
</div>

Python: "Indentation Error: unindent does not match any outer indentation level"

I am using gedit basic version that comes with Ubuntu 11.10. I had the same error. This is mainly caused when you mix spaces with tabs.

A good way to differentiate as to which lines have problem would be to go to: 1. edit 2. preferences 3. editor 4. check "automatic indentation" 5. increase the indentation to 12 or some big number

after doing the fifth step you will be able to see the lines of your code that are relly causing problem (these are the lines that have a mix of space and tab)

Make the entire code convention as just TAB or just SPACE (this has to be done manually line by line)

Hope this helps...

How to create cron job using PHP?

First open your SSH server with username and password and change to the default root user(User with all permissions) then follow the steps below,

  1. enter the command crontab -l now you will see the list of all cronjobs.
  2. enter crontab -e a file with all cron jobs will be opened.
  3. Edit the file with your cronjob schedule as min hr dayofmonth month dayofweek pathtocronjobfile and save the file.
  4. Now you will see a response crontab: installing new crontab now again check the list of cronjobs your cron job will be listed there.

How to round a floating point number up to a certain decimal place?

Just for the record. You could do it this way:

def roundno(no):
    return int(no//1 + ((no%1)/0.5)//1)

There, no need for includes/imports

Output single character in C

The easiest way to output a single character is to simply use the putchar function. After all, that's it's sole purpose and it cannot do anything else. It cannot be simpler than that.

Clear input fields on form submit

Still using empty strings you can use:

document.getElementById("name").value = '';
document.getElementById("review").value = '';

replace anchor text with jquery

$('#link1').text("Replacement text");

The .text() method drops the text you pass it into the element content. Unlike using .html(), .text() implicitly ignores any embedded HTML markup, so if you need to embed some inline <span>, <i>, or whatever other similar elements, use .html() instead.

Getting a better understanding of callback functions in JavaScript

There are 3 main possibilities to execute a function:

var callback = function(x, y) {
    // "this" may be different depending how you call the function
    alert(this);
};
  1. callback(argument_1, argument_2);
  2. callback.call(some_object, argument_1, argument_2);
  3. callback.apply(some_object, [argument_1, argument_2]);

The method you choose depends whether:

  1. You have the arguments stored in an Array or as distinct variables.
  2. You want to call that function in the context of some object. In this case, using the "this" keyword in that callback would reference the object passed as argument in call() or apply(). If you don't want to pass the object context, use null or undefined. In the latter case the global object would be used for "this".

Docs for Function.call, Function.apply

HTML 5 Geo Location Prompt in Chrome

For an easy workaround, just copy the HTML file to some cloud share, such as Dropbox, and use the shared link in your browser. Easy.

Check input value length

<input type='text' minlength=3 /><br />

if browser supports html5,

it will automatical be validate attributes(minlength) in tag

but Safari(iOS) doesn't working

Get class name of object as string in Swift

Swift 5.1 :-

You can also use generic function for get class name of object as string

struct GenericFunctions {
 static func className<T>(_ name: T) -> String {
        return "\(name)"
    }

}

Call this function by using following:-

let name = GenericFunctions.className(ViewController.self)

Happy Coding :)

jQuery click / toggle between two functions

I don't think you should implement the toggle method since there is a reason why it was removed from jQuery 1.9.

Consider using toggleClass instead that is fully supported by jQuery:

function a(){...}
function b(){...}   

Let's say for example that your event trigger is onclick, so:

First option:

$('#test').on('click', function (event) {

    $(this).toggleClass('toggled');

    if ($(this).hasClass('toggled')) {
        a();
    } else{
        b();
    }
}

You can also send the handler functions as parameters:

Second option:

$('#test').on('click',{handler1: a, handler2: b}, function (event) {

    $(this).toggleClass('toggled');

    if ($(this).hasClass('toggled')) {
        event.data.handler1();
    } else{
        event.data.handler2();
    }
}

How to check "hasRole" in Java Code with Spring Security?

Strangely enough, I don't think there is a standard solution to this problem, as the spring-security access control is expression based, not java-based. you might check the source code for DefaultMethodSecurityExpressionHandler to see if you can re-use something they are doing there

Validation failed for one or more entities. See 'EntityValidationErrors' property for more details

This works for me.

var modelState = ModelState.Values;
if (!ModelState.IsValid)
{
    return RedirectToAction("Index", "Home", model);
}

Put a breakpoint on if statement. Then you can check modelState in debug windows. On every value you can see if there is an error and even the error message. That's it. When you don't need it anymore, just delete or comment the line.

I hope this will help.

If asked, I can provide detailed screenshot in the debug window.

PHP - auto refreshing page

Try out this as well. Your page will refresh every 10sec

<html>
 <head>

  <meta http-equiv="refresh" content="10; url="<?php echo $_SERVER['PHP_SELF']; ?>">
 </head>
 <body>

 </body>
</html>

Simple dynamic breadcrumb

Also made a little script using RDFa (you can also use microdata or other formats) Check it out on google This script also keeps in mind your site structure.

function breadcrumbs($text = 'You are here: ', $sep = ' &raquo; ', $home = 'Home') {
//Use RDFa breadcrumb, can also be used for microformats etc.
$bc     =   '<div xmlns:v="http://rdf.data-vocabulary.org/#" id="crums">'.$text;
//Get the website:
$site   =   'http://'.$_SERVER['HTTP_HOST'];
//Get all vars en skip the empty ones
$crumbs =   array_filter( explode("/",$_SERVER["REQUEST_URI"]) );
//Create the home breadcrumb
$bc    .=   '<span typeof="v:Breadcrumb"><a href="'.$site.'" rel="v:url" property="v:title">'.$home.'</a>'.$sep.'</span>'; 
//Count all not empty breadcrumbs
$nm     =   count($crumbs);
$i      =   1;
//Loop the crumbs
foreach($crumbs as $crumb){
    //Make the link look nice
    $link    =  ucfirst( str_replace( array(".php","-","_"), array(""," "," ") ,$crumb) );
    //Loose the last seperator
    $sep     =  $i==$nm?'':$sep;
    //Add crumbs to the root
    $site   .=  '/'.$crumb;
    //Make the next crumb
    $bc     .=  '<span typeof="v:Breadcrumb"><a href="'.$site.'" rel="v:url" property="v:title">'.$link.'</a>'.$sep.'</span>';
    $i++;
}
$bc .=  '</div>';
//Return the result
return $bc;}

Copy map values to vector in STL

We should use the transform function from STL algorithm, the last parameter of transform function could be a function object, function pointer or a lambda function that convert item of map to item of vector. This case map have items have type pair that need to convert to item that has int type for vector. Here is my solution that I use lambda function:

#include <algorithm> // for std::transform
#include <iterator>  // for back_inserted

// Map of pair <int, string> need to convert to vector of string
std::map<int, std::string> mapExp = { {1, "first"}, {2, "second"}, {3, "third"}, {4,"fourth"} };

// vector of string to store the value type of map
std::vector<std::string> vValue;

// Convert function
std::transform(mapExp.begin(), mapExp.end(), std::back_inserter(vValue),
       [](const std::pair<int, string> &mapItem)
       {
         return mapItem.second;
       });

What is the meaning of "this" in Java?

this can be used inside some method or constructor.

It returns the reference to the current object.

What is an efficient way to implement a singleton pattern in Java?

I still think after Java 1.5, enum is the best available singleton implementation available as it also ensures that, even in the multi threaded environments, only one instance is created.

public enum Singleton {
    INSTANCE;
}

And you are done!

unix - count of columns in file

If you have python installed you could try:

python -c 'import sys;f=open(sys.argv[1]);print len(f.readline().split("|"))' \
    stores.dat

How do you add UI inside cells in a google spreadsheet using app script?

The apps UI only works for panels.

The best you can do is to draw a button yourself and put that into your spreadsheet. Than you can add a macro to it.

Go into "Insert > Drawing...", Draw a button and add it to the spreadsheet. Than click it and click "assign Macro...", then insert the name of the function you wish to execute there. The function must be defined in a script in the spreadsheet.

Alternatively you can also draw the button somewhere else and insert it as an image.

More info: https://developers.google.com/apps-script/guides/menus

enter image description here enter image description here enter image description here

Create a OpenSSL certificate on Windows

You can download a native OpenSSL for Windows, or you can always use Cygwin.

How to format an inline code in Confluence?

I found formatting with colors a bit trickier as Confluence (5.6.3) is very fussy about spaces around the {{monospace}} blocks.

Creating Colored Monospace with Wiki Markup

As rendered by Confluence

HTML - how can I show tooltip ONLY when ellipsis is activated

You could possibly surround the span with another span, then simply test if the width of the original/inner span is greater than that of the new/outer span. Note that I say possibly -- it is roughly based on my situation where I had a span inside of a td so I don't actually know that if it will work with a span inside of a span.

Here though is my code for others who may find themselves in a position similar to mine; I'm copying/pasting it without modification even though it is in an Angular context, I don't think that detracts from the readability and the essential concept. I coded it as a service method because I needed to apply it in more than one place. The selector I've been passing in has been a class selector that will match multiple instances.

CaseService.applyTooltip = function(selector) {
    angular.element(selector).on('mouseenter', function(){
        var td = $(this)
        var span = td.find('span');

        if (!span.attr('tooltip-computed')) {
            //compute just once
            span.attr('tooltip-computed','1');

            if (span.width() > td.width()){
                span.attr('data-toggle','tooltip');
                span.attr('data-placement','right');
                span.attr('title', span.html());
            }
        }
    });
}

VBA: Conditional - Is Nothing

In my sample code, I was setting my object to nothing, and I couldn't get the "not" part of the if statement to work with the object. I tried if My_Object is not nothing and also if not My_Object is nothing. It may be just a syntax thing I can't figure out but I didn't have time to mess around, so I did a little workaround like this:

if My_Object is Nothing Then
    'do nothing
Else
    'Do something
End if

What are 'get' and 'set' in Swift?

The getting and setting of variables within classes refers to either retrieving ("getting") or altering ("setting") their contents.

Consider a variable members of a class family. Naturally, this variable would need to be an integer, since a family can never consist of two point something people.

So you would probably go ahead by defining the members variable like this:

class family {
   var members:Int
}

This, however, will give people using this class the possibility to set the number of family members to something like 0 or 1. And since there is no such thing as a family of 1 or 0, this is quite unfortunate.

This is where the getters and setters come in. This way you can decide for yourself how variables can be altered and what values they can receive, as well as deciding what content they return.

Returning to our family class, let's make sure nobody can set the members value to anything less than 2:

class family {
  var _members:Int = 2
  var members:Int {
   get {
     return _members
   }
   set (newVal) {
     if newVal >= 2 {
       _members = newVal
     } else {
       println('error: cannot have family with less than 2 members')
     }
   }
  }
}

Now we can access the members variable as before, by typing instanceOfFamily.members, and thanks to the setter function, we can also set it's value as before, by typing, for example: instanceOfFamily.members = 3. What has changed, however, is the fact that we cannot set this variable to anything smaller than 2 anymore.

Note the introduction of the _members variable, which is the actual variable to store the value that we set through the members setter function. The original members has now become a computed property, meaning that it only acts as an interface to deal with our actual variable.

dynamically set iframe src

You should also consider that in some Opera versions onload is fired several times and add some hooks:

// fixing Opera 9.26, 10.00
if (doc.readyState && doc.readyState != 'complete') {
    // Opera fires load event multiple times
    // Even when the DOM is not ready yet
    // this fix should not affect other browsers
    return;
}

// fixing Opera 9.64
if (doc.body && doc.body.innerHTML == "false") {
    // In Opera 9.64 event was fired second time
    // when body.innerHTML changed from false
    // to server response approx. after 1 sec
    return;
}

Code borrowed from Ajax Upload

Using Switch Statement to Handle Button Clicks

One way of achieving this is to make your class implement OnClickListener and then add it to your buttons like this:

Example:

//make your class implement OnClickListener
public class MyClass implements OnClickListener{

        ...

        //Create your buttons and set their onClickListener to "this"
        Button b1 = (Button) findViewById(R.id.buttonplay);   
        b1.setOnClickListener(this);

        Button b2 = (Button) findViewById(R.id.buttonstop);   
        b2.setOnClickListener(this);

        ...

        //implement the onClick method here
        public void onClick(View v) {
           // Perform action on click
          switch(v.getId()) {
            case R.id.buttonplay:
              //Play voicefile
              MediaPlayer.create(getBaseContext(), R.raw.voicefile).start();
              break;
            case R.id.buttonstop:
              //Stop MediaPlayer
              MediaPlayer.create(getBaseContext(), R.raw.voicefile).stop();
              break;
          }
       }
}

For more information see Android Developers > Handling UI Events.

div hover background-color change?

div hover background color change

Try like this:

.class_name:hover{
    background-color:#FF0000;
}

Convert Map<String,Object> to Map<String,String>

There are two ways to do this. One is very simple but unsafe:

Map<String, Object> map = new HashMap<String, Object>();
Map<String, String> newMap = new HashMap<String, String>((Map)map);  // unchecked warning

The other way has no compiler warnings and ensures type safety at runtime, which is more robust. (After all, you can't guarantee the original map contains only String values, otherwise why wouldn't it be Map<String, String> in the first place?)

Map<String, Object> map = new HashMap<String, Object>();
Map<String, String> newMap = new HashMap<String, String>();
@SuppressWarnings("unchecked") Map<String, Object> intermediate =
    (Map)Collections.checkedMap(newMap, String.class, String.class);
intermediate.putAll(map);

Angular js init ng-model from default values

As others pointed out, it is not good practice to initialize data on views. Initializing data on Controllers, however, is recommended. (see http://docs.angularjs.org/guide/controller)

So you can write

<input name="card[description]" ng-model="card.description">

and

$scope.card = { description: 'Visa-4242' };

$http.get('/getCardInfo.php', function(data) {
   $scope.card = data;
});

This way the views do not contain data, and the controller initializes the value while the real values are being loaded.

link button property to open in new tab?

try by Adding following onClientClick event.

OnClientClick="aspnetForm.target ='_blank';"

so on click it will call Javascript function an will open respective link in News tab.

<asp:LinkButton id="lbnkVidTtile1" OnClientClick="aspnetForm.target ='_blank';" runat="Server" CssClass="bodytext" Text='<%# Eval("newvideotitle") %>'  />

Windows equivalent of OS X Keychain?

If you are on windows got to control pannel -> windows Credentials

UnsupportedClassVersionError: JVMCFRE003 bad major version in WebSphere AS 7

I was getting the same error even after doing above changes and what i did is

Right click on the project->properties->java compiler->Compiler compliance level->changes it to 1.6

This change is particular for the project. This should hopefully work.

How to display an alert box from C# in ASP.NET?

You can create a global method to show message(alert) in your web form application.

public static class PageUtility
{
    public static void MessageBox(System.Web.UI.Page page,string strMsg)
    {
        //+ character added after strMsg "')"
        ScriptManager.RegisterClientScriptBlock(page, page.GetType(), "alertMessage", "alert('" + strMsg + "')", true);

    }
}

webform.aspx

protected void btnSave_Click(object sender, EventArgs e)
{
    PageUtility.MessageBox(this, "Success !");
}

Removing duplicates from a String in Java

Try this simple solution:

public String removeDuplicates(String input){
    String result = "";
    for (int i = 0; i < input.length(); i++) {
        if(!result.contains(String.valueOf(input.charAt(i)))) {
            result += String.valueOf(input.charAt(i));
        }
    }
    return result;
}

How to pass the -D System properties while testing on Eclipse?

You can add command line arguments to your run configuration. Just edit the run configuration and add -Dmyprop=value (or whatever) to the VM Arguments Box.

Integrity constraint violation: 1452 Cannot add or update a child row:

If you are adding new foreign key to an existing table and the columns are not null and not assigned default value, you will get this error,

Either you need to make it nullable or assign default value, or delete all the existing records to solve it.

jquery smooth scroll to an anchor?

Using hanoo's script I created a jQuery function:

$.fn.scrollIntoView = function(duration, easing) {
    var dest = 0;
    if (this.offset().top > $(document).height() - $(window).height()) {
        dest = $(document).height() - $(window).height();
    } else {
        dest = this.offset().top;
    }
    $('html,body').animate({
        scrollTop: dest
    }, duration, easing);
    return this;
};

usage:

$('#myelement').scrollIntoView();

Defaults for duration and easing are 400ms and "swing".

What is the best IDE to develop Android apps in?

I've been using IntelliJ IDEA for the last 12 months now as my main IDE, but I am often forced to use Eclipse as well. So when I have to work in Eclipse I start biting my nails. I will sum up my pros and cons.

Eclipse pros:
- visual editor. IDEA has one as well, but it's rather primitive. I suspect that this feature will soon be deleted as IDEA will improve its editor.
- many projects into one right pane (this is also my personal con as I like IDEA's one-project-per-pane thing)
- faster compiles Android projects. IDEA has made its compilation process faster, so I also soon expect to delete this Eclipse pro

IDEA pros:
- faster intellisense (if you like Resharper, then you know what I am talking about)
- smarter autocomplete - my friend and I decided to write the same class. I finished before him simply because IDEA faster reacts to my wishes
- incredibly smart - do not know what to do? just press Ctrl+Shift+Space and IDEA will tell you what should come there. It also recognizes naming scheme to if you're filling name object, it will first display getName method.
- will add more as I remember of them

IDEA cons:
- Still the only con is that if you open Eclipse Android project and edit any XML layout file, Eclipse will no longer be able to display edited file into its visual layout editor. This has not been fixed as of this day and it's IDEA's bug as it somehow messes the XML.

Bottom line: if you're a person who does not see advantages of ReSharper in .NET (and we all coded in .NET), then you'll probably stick to Eclipse. It's official Android IDE and you believe it's the best.
If you liked ReSharper and want to code faster, then you'll appreciate IDEA and will stick to it forever.

How to find schema name in Oracle ? when you are connected in sql session using read only user

To create a read-only user, you have to setup a different user than the one owning the tables you want to access.

If you just create the user and grant SELECT permission to the read-only user, you'll need to prepend the schema name to each table name. To avoid this, you have basically two options:

  1. Set the current schema in your session:
ALTER SESSION SET CURRENT_SCHEMA=XYZ
  1. Create synonyms for all tables:
CREATE SYNONYM READER_USER.TABLE1 FOR XYZ.TABLE1

So if you haven't been told the name of the owner schema, you basically have three options. The last one should always work:

  1. Query the current schema setting:
SELECT SYS_CONTEXT('USERENV','CURRENT_SCHEMA') FROM DUAL
  1. List your synonyms:
SELECT * FROM ALL_SYNONYMS WHERE OWNER = USER
  1. Investigate all tables (with the exception of the some well-known standard schemas):
SELECT * FROM ALL_TABLES WHERE OWNER NOT IN ('SYS', 'SYSTEM', 'CTXSYS', 'MDSYS');

Replace whole line containing a string using Sed

To replace whole line containing a specified string with the content of that line

Text file:

Row: 0 last_time_contacted=0, display_name=Mozart, _id=100, phonebook_bucket_alt=2
Row: 1 last_time_contacted=0, display_name=Bach, _id=101, phonebook_bucket_alt=2

Single string:

$ sed 's/.* display_name=\([[:alpha:]]\+\).*/\1/'
output:
100
101

Multiple strings delimited by white-space:

$ sed 's/.* display_name=\([[:alpha:]]\+\).* _id=\([[:digit:]]\+\).*/\1 \2/'
output:
Mozart 100
Bach 101

Adjust regex to meet your needs

[:alpha] and [:digit:] are Character Classes and Bracket Expressions

How to display Wordpress search results?

Basically, you need to include the Wordpress loop in your search.php template to loop through the search results and show them as part of the template.

Below is a very basic example from The WordPress Theme Search Template and Page Template over at ThemeShaper.

<?php
/**
 * The template for displaying Search Results pages.
 *
 * @package Shape
 * @since Shape 1.0
 */

get_header(); ?>

        <section id="primary" class="content-area">
            <div id="content" class="site-content" role="main">

            <?php if ( have_posts() ) : ?>

                <header class="page-header">
                    <h1 class="page-title"><?php printf( __( 'Search Results for: %s', 'shape' ), '<span>' . get_search_query() . '</span>' ); ?></h1>
                </header><!-- .page-header -->

                <?php shape_content_nav( 'nav-above' ); ?>

                <?php /* Start the Loop */ ?>
                <?php while ( have_posts() ) : the_post(); ?>

                    <?php get_template_part( 'content', 'search' ); ?>

                <?php endwhile; ?>

                <?php shape_content_nav( 'nav-below' ); ?>

            <?php else : ?>

                <?php get_template_part( 'no-results', 'search' ); ?>

            <?php endif; ?>

            </div><!-- #content .site-content -->
        </section><!-- #primary .content-area -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>

How to ping an IP address


Just an addition to what others have given, even though they work well but in some cases if internet is slow or some unknown network problem exists, some of the codes won't work (isReachable()). But this code mentioned below creates a process which acts as a command line ping (cmd ping) to windows. It works for me in all cases, tried and tested.

Code :-

public class JavaPingApp {

public static void runSystemCommand(String command) {

    try {
        Process p = Runtime.getRuntime().exec(command);
        BufferedReader inputStream = new BufferedReader(
                new InputStreamReader(p.getInputStream()));

        String s = "";
        // reading output stream of the command
        while ((s = inputStream.readLine()) != null) {
            System.out.println(s);
        }

    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) {

    String ip = "stackoverflow.com"; //Any IP Address on your network / Web
    runSystemCommand("ping " + ip);
}
}

Hope it helps, Cheers!!!

How to measure elapsed time

From Java 8 onward you can try the following:

import java.time.*;
import java.time.temporal.ChronoUnit;

Instant start_time = Instant.now();
// Your code
Instant stop_time = Instant.now();

System.out.println(Duration.between(start_time, stop_time).toMillis());

//or

System.out.println(ChronoUnit.MILLIS.between(start_time, stop_time));

Parsing date string in Go

As answered but to save typing out "2006-01-02T15:04:05.000Z" for the layout, you could use the package's constant RFC3339.

str := "2014-11-12T11:45:26.371Z"
t, err := time.Parse(time.RFC3339, str)

if err != nil {
    fmt.Println(err)
}
fmt.Println(t)

https://play.golang.org/p/Dgu2ZvHwTh

React component not re-rendering on state change

Another oh-so-easy mistake, which was the source of the problem for me: I’d written my own shouldComponentUpdate method, which didn’t check the new state change I’d added.

Mysql: Setup the format of DATETIME to 'DD-MM-YYYY HH:MM:SS' when creating a table

No you can't; datetime will be stored in default format only while creating table and then you can change the display format in you select query the way you want using the Mysql Date Time Functions

Can I set up HTML/Email Templates with ASP.NET?

DotLiquid is another option. You specify values from a class model as {{ user.name }} and then at runtime you provide the data in that class, and the template with the markup, and it will merge the values in for you. It is similar to using the Razor templating engine in many ways. It supports more complex things like loops and various function like ToUpper. The nice thing is these are "safe" so that user's who create the templates can't crash your system or write unsafe code like you would in razor: http://dotliquidmarkup.org/try-online

HTTP Ajax Request via HTTPS Page

From the javascript I tried from several ways and I could not.

You need an server side solution, for example on c# I did create an controller that call to the http, en deserialize the object, and the result is that when I call from javascript, I'm doing an request from my https://domain to my htpps://domain. Please see my c# code:

[Authorize]
public class CurrencyServicesController : Controller
{
    HttpClient client;
    //GET: CurrencyServices/Consultar?url=valores?moedas=USD&alt=json
    public async Task<dynamic> Consultar(string url)
    {
        client = new HttpClient();
        client.BaseAddress = new Uri("http://api.promasters.net.br/cotacao/v1/");
        client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
        System.Net.Http.HttpResponseMessage response = client.GetAsync(url).Result;

        var FromURL = response.Content.ReadAsStringAsync().Result;

        return JsonConvert.DeserializeObject(FromURL);
    }

And let me show to you my client side (Javascript)

<script async>
$(document).ready(function (data) {

    var TheUrl = '@Url.Action("Consultar", "CurrencyServices")?url=valores';
    $.getJSON(TheUrl)
        .done(function (data) {
            $('#DolarQuotation').html(
                '$ ' + data.valores.USD.valor.toFixed(2) + ','
            );
            $('#EuroQuotation').html(
                '€ ' + data.valores.EUR.valor.toFixed(2) + ','
            );

            $('#ARGPesoQuotation').html(
                'Ar$ ' + data.valores.ARS.valor.toFixed(2) + ''
            );

        });       

});

I wish that this help you! Greetings

How to count the number of rows in excel with data?

For greater clarity, I want to add a clear example and running

            openFileDialog1.FileName = "Select File"; 
            openFileDialog1.DefaultExt = ".xls"; 
            openFileDialog1.Filter = "Excel documents (.xls)|*.xls"; 


            DialogResult result = openFileDialog1.ShowDialog();


            if (result==DialogResult.OK)
            {

                string filename = openFileDialog1.FileName;


                Excel.Application xlApp;
                Excel.Workbook xlWorkBook;
                Excel.Worksheet xlWorkSheet;
                object misValue = System.Reflection.Missing.Value;

                xlApp = new Excel.Application();
                xlApp.Visible = false;
                xlApp.DisplayAlerts = false;



                xlWorkBook = xlApp.Workbooks.Open(filename, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);

                xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

                var numRows = xlWorkSheet.Range["A1"].Offset[xlWorkSheet.Rows.Count - 1, 0].End[Excel.XlDirection.xlUp].Row;

                MessageBox.Show("Number of max row is : "+ numRows.ToString());

                xlWorkBook.Close(true, misValue, misValue);
                xlApp.Quit();

            }

Set title background color

protected void onCreate(Bundle savedInstanceState) {        
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    View titleView = getWindow().findViewById(android.R.id.title);
    if (titleView != null) {
      ViewParent parent = titleView.getParent();
      if (parent != null && (parent instanceof View)) {
        View parentView = (View)parent;
        parentView.setBackgroundColor(Color.RED);
      }
    }

on above code you can try you can use title instead of titlebar this will affect on all activity in your application

Android studio 3.0: Unable to resolve dependency for :app@dexOptions/compileClasspath': Could not resolve project :animators

Step 1:
1.Open the Preferences, by clicking File > Settings (on Mac, Android Studio > Preferences).
2.In the left pane, click Build, Execution, Deployment >> Gradle.
3.Uncheck/disable the Offline work checkbox.
4.Click Apply or OK.

Step 2:
downgrade the gradle-wrapper.properties content which you can access this 
file directory by clicking on CTRL + SHFT +R KEY 
e.g from
    distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip

to 
    distributionUrl=https\://services.gradle.org/distributions/gradle-4.0-all.zip

or to any lower version like /gradle-3.9-all.zip or /gradle-3.8-all.zip

Android, How to read QR code in my application?

Easy QR Code Library

A simple Android Easy QR Code Library. It is very easy to use, to use this library follow these steps.

For Gradle:

Step 1. Add it in your root build.gradle at the end of repositories:

allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}

Step 2. Add the dependency:

dependencies {
        compile 'com.github.mrasif:easyqrlibrary:v1.0.0'
}

For Maven:

Step 1. Add the JitPack repository to your build file:

<repositories>
    <repository>
        <id>jitpack.io</id>
        <url>https://jitpack.io</url>
    </repository>
</repositories>

Step 2. Add the dependency:

<dependency>
    <groupId>com.github.mrasif</groupId>
    <artifactId>easyqrlibrary</artifactId>
    <version>v1.0.0</version>
</dependency>

For SBT:

Step 1. Add the JitPack repository to your build.sbt file:

resolvers += "jitpack" at "https://jitpack.io"

Step 2. Add the dependency:

libraryDependencies += "com.github.mrasif" % "easyqrlibrary" % "v1.0.0"

For Leiningen:

Step 1. Add it in your project.clj at the end of repositories:

:repositories [["jitpack" "https://jitpack.io"]]

Step 2. Add the dependency:

:dependencies [[com.github.mrasif/easyqrlibrary "v1.0.0"]]

Add this in your layout xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="20dp"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tvData"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="No QR Data"/>
    <Button
        android:id="@+id/btnQRScan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="QR Scan"/>

</LinearLayout>

Add this in your activity java files:

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    TextView tvData;
    Button btnQRScan;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvData=findViewById(R.id.tvData);
        btnQRScan=findViewById(R.id.btnQRScan);

        btnQRScan.setOnClickListener(this);
    }

    @Override
    public void onClick(View view){
        switch (view.getId()){
            case R.id.btnQRScan: {
                Intent intent=new Intent(MainActivity.this, QRScanner.class);
                startActivityForResult(intent, EasyQR.QR_SCANNER_REQUEST);
            } break;
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        switch (requestCode){
            case EasyQR.QR_SCANNER_REQUEST: {
                if (resultCode==RESULT_OK){
                    tvData.setText(data.getStringExtra(EasyQR.DATA));
                }
            } break;
        }
    }
}

For customized scanner screen just add these lines when you start the scanner Activity.

Intent intent=new Intent(MainActivity.this, QRScanner.class);
intent.putExtra(EasyQR.IS_TOOLBAR_SHOW,true);
intent.putExtra(EasyQR.TOOLBAR_DRAWABLE_ID,R.drawable.ic_audiotrack_dark);
intent.putExtra(EasyQR.TOOLBAR_TEXT,"My QR");
intent.putExtra(EasyQR.TOOLBAR_BACKGROUND_COLOR,"#0588EE");
intent.putExtra(EasyQR.TOOLBAR_TEXT_COLOR,"#FFFFFF");
intent.putExtra(EasyQR.BACKGROUND_COLOR,"#000000");
intent.putExtra(EasyQR.CAMERA_MARGIN_LEFT,50);
intent.putExtra(EasyQR.CAMERA_MARGIN_TOP,50);
intent.putExtra(EasyQR.CAMERA_MARGIN_RIGHT,50);
intent.putExtra(EasyQR.CAMERA_MARGIN_BOTTOM,50);
startActivityForResult(intent, EasyQR.QR_SCANNER_REQUEST);

You are done. Ref. Link: https://mrasif.github.io/easyqrlibrary

How to get jQuery to wait until an effect is finished?

You can as well use $.when() to wait until the promise finished:

var myEvent = function() {
    $( selector ).fadeOut( 'fast' );
};
$.when( myEvent() ).done( function() {
    console.log( 'Task finished.' );
} );

In case you're doing a request that could as well fail, then you can even go one step further:

$.when( myEvent() )
    .done( function( d ) {
        console.log( d, 'Task done.' );
    } )
    .fail( function( err ) {
        console.log( err, 'Task failed.' );
    } )
    // Runs always
    .then( function( data, textStatus, jqXHR ) {
        console.log( jqXHR.status, textStatus, 'Status 200/"OK"?' );
    } );

How to get input field value using PHP

function get_input_tags($html)
{
    $post_data = array();

    // a new dom object
    $dom = new DomDocument; 

    //load the html into the object
    $dom->loadHTML($html); 
    //discard white space
    $dom->preserveWhiteSpace = false; 

    //all input tags as a list
    $input_tags = $dom->getElementsByTagName('input'); 

    //get all rows from the table
    for ($i = 0; $i < $input_tags->length; $i++) 
    {
        if( is_object($input_tags->item($i)) )
        {
            $name = $value = '';
            $name_o = $input_tags->item($i)->attributes->getNamedItem('name');
            if(is_object($name_o))
            {
                $name = $name_o->value;

                $value_o = $input_tags->item($i)->attributes->getNamedItem('value');
                if(is_object($value_o))
                {
                    $value = $input_tags->item($i)->attributes->getNamedItem('value')->value;
                }

                $post_data[$name] = $value;
            }
        }
    }

    return $post_data; 
}

error_reporting(~E_WARNING);
$html = file_get_contents("https://accounts.google.com/ServiceLoginAuth");

print_r(get_input_tags($html));

How can I copy columns from one sheet to another with VBA in Excel?

Selecting is often unnecessary. Try this

Sub OneCell()
    Sheets("Sheet2").range("B1:B3").value = Sheets("Sheet1").range("A1:A3").value
End Sub

Visual Studio 2017 - Could not load file or assembly 'System.Runtime, Version=4.1.0.0' or one of its dependencies

I had this error occur when building an Azure Function (with a queue trigger, should it make a difference)

The issue in this case was because the AzureFunctionsVersion was set to v2 instead of v3. To update it via VS2019, unload the project then edit the csproj file. Within the PropertyGroup node, add/edit the following:

<PropertyGroup>
  <AzureFunctionsVersion>v3</AzureFunctionsVersion>
</PropertyGroup>

How to get current route in react-router 2.0.0-rc5

For any users having the same issue in 2017, I solved it the following way:

NavBar.contextTypes = {
    router: React.PropTypes.object,
    location: React.PropTypes.object
}

and use it like this:

componentDidMount () {
    console.log(this.context.location.pathname);
}

Convert hex string to int

For those of you who need to convert hexadecimal representation of a signed byte from two-character String into byte (which in Java is always signed), there is an example. Parsing a hexadecimal string never gives negative number, which is faulty, because 0xFF is -1 from some point of view (two's complement coding). The principle is to parse the incoming String as int, which is larger than byte, and then wrap around negative numbers. I'm showing only bytes, so that example is short enough.

String inputTwoCharHex="FE"; //whatever your microcontroller data is

int i=Integer.parseInt(inputTwoCharHex,16);
//negative numbers is i now look like 128...255

// shortly i>=128
if (i>=Integer.parseInt("80",16)){

    //need to wrap-around negative numbers
    //we know that FF is 255 which is -1
    //and FE is 254 which is -2 and so on
    i=-1-Integer.parseInt("FF",16)+i;
    //shortly i=-256+i;
}
byte b=(byte)i;
//b is now surely between -128 and +127

This can be edited to process longer numbers. Just add more FF's or 00's respectively. For parsing 8 hex-character signed integers, you need to use Long.parseLong, because FFFF-FFFF, which is integer -1, wouldn't fit into Integer when represented as a positive number (gives 4294967295). So you need Long to store it. After conversion to negative number and casting back to Integer, it will fit. There is no 8 character hex string, that wouldn't fit integer in the end.

File tree view in Notepad++

Tree like structure in Notepad++ without plugin

Download Notepad++ 6.8.8 & then follow step below :

Notepad++ -> View-> Project-> choose Panel 1 OR Panel 2 OR Panel 3 ->

It will create a sub part Wokspace on the left side -> Right click on Workspace & click Add Project -> Again right click on Project which is created recently -> And click on Add Files From Directory.

This is it. Enjoy

Simplest way to have a configuration file in a Windows Forms C# application

Use:

System.Configuration.ConfigurationSettings.AppSettings["MyKey"];

AppSettings has been deprecated and is now considered obsolete (link).

In addition, the appSettings section of the app.config has been replaced by the applicationSettings section.

As someone else mentioned, you should be using System.Configuration.ConfigurationManager (link) which is new for .NET 2.0.

Finding all possible permutations of a given string in python

Here's a slightly improved version of illerucis's code for returning a list of all permutations of a string s with distinct characters (not necessarily in lexicographic sort order), without using itertools:

def get_perms(s, i=0):
    """
    Returns a list of all (len(s) - i)! permutations t of s where t[:i] = s[:i].
    """
    # To avoid memory allocations for intermediate strings, use a list of chars.
    if isinstance(s, str):
        s = list(s)

    # Base Case: 0! = 1! = 1.
    # Store the only permutation as an immutable string, not a mutable list.
    if i >= len(s) - 1:
        return ["".join(s)]

    # Inductive Step: (len(s) - i)! = (len(s) - i) * (len(s) - i - 1)!
    # Swap in each suffix character to be at the beginning of the suffix.
    perms = get_perms(s, i + 1)
    for j in range(i + 1, len(s)):
        s[i], s[j] = s[j], s[i]
        perms.extend(get_perms(s, i + 1))
        s[i], s[j] = s[j], s[i]
    return perms

Java Minimum and Maximum values in Array

You just throw away Min/Max values:

  // get biggest number
  getMaxValue(array); // <- getMaxValue returns value, which is ignored
  // get smallest number
  getMinValue(array); // <- getMinValue returns value, which is ignored as well

You can do something like

  ... 
  array[i] = next;

  System.out.print("Max value = ");
  System.out.println(getMaxValue(array)); // <- Print out getMaxValue value

  System.out.print("Min value = ");
  System.out.println(getMinValue(array)); // <- Print out getMinValue value

  ...  

Debugging Spring configuration

If you use Spring Boot, you can also enable a “debug” mode by starting your application with a --debug flag.

java -jar myapp.jar --debug

You can also specify debug=true in your application.properties.

When the debug mode is enabled, a selection of core loggers (embedded container, Hibernate, and Spring Boot) are configured to output more information. Enabling the debug mode does not configure your application to log all messages with DEBUG level.

Alternatively, you can enable a “trace” mode by starting your application with a --trace flag (or trace=true in your application.properties). Doing so enables trace logging for a selection of core loggers (embedded container, Hibernate schema generation, and the whole Spring portfolio).

https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html

Using @property versus getters and setters

I feel like properties are about letting you get the overhead of writing getters and setters only when you actually need them.

Java Programming culture strongly advise to never give access to properties, and instead, go through getters and setters, and only those which are actually needed. It's a bit verbose to always write these obvious pieces of code, and notice that 70% of the time they are never replaced by some non-trivial logic.

In Python, people actually care for that kind of overhead, so that you can embrace the following practice :

  • Do not use getters and setters at first, when if they not needed
  • Use @property to implement them without changing the syntax of the rest of your code.

How to remove from a map while iterating it?

In short "How do I remove from a map while iterating it?"

  • With old map impl: You can't
  • With new map impl: almost as @KerrekSB suggested. But there are some syntax issues in what he posted.

From GCC map impl (note GXX_EXPERIMENTAL_CXX0X):

#ifdef __GXX_EXPERIMENTAL_CXX0X__
      // _GLIBCXX_RESOLVE_LIB_DEFECTS
      // DR 130. Associative erase should return an iterator.
      /**
       *  @brief Erases an element from a %map.
       *  @param  position  An iterator pointing to the element to be erased.
       *  @return An iterator pointing to the element immediately following
       *          @a position prior to the element being erased. If no such 
       *          element exists, end() is returned.
       *
       *  This function erases an element, pointed to by the given
       *  iterator, from a %map.  Note that this function only erases
       *  the element, and that if the element is itself a pointer,
       *  the pointed-to memory is not touched in any way.  Managing
       *  the pointer is the user's responsibility.
       */
      iterator
      erase(iterator __position)
      { return _M_t.erase(__position); }
#else
      /**
       *  @brief Erases an element from a %map.
       *  @param  position  An iterator pointing to the element to be erased.
       *
       *  This function erases an element, pointed to by the given
       *  iterator, from a %map.  Note that this function only erases
       *  the element, and that if the element is itself a pointer,
       *  the pointed-to memory is not touched in any way.  Managing
       *  the pointer is the user's responsibility.
       */
      void
      erase(iterator __position)
      { _M_t.erase(__position); }
#endif

Example with old and new style:

#include <iostream>
#include <map>
#include <vector>
#include <algorithm>

using namespace std;
typedef map<int, int> t_myMap;
typedef vector<t_myMap::key_type>  t_myVec;

int main() {

    cout << "main() ENTRY" << endl;

    t_myMap mi;
    mi.insert(t_myMap::value_type(1,1));
    mi.insert(t_myMap::value_type(2,1));
    mi.insert(t_myMap::value_type(3,1));
    mi.insert(t_myMap::value_type(4,1));
    mi.insert(t_myMap::value_type(5,1));
    mi.insert(t_myMap::value_type(6,1));

    cout << "Init" << endl;
    for(t_myMap::const_iterator i = mi.begin(); i != mi.end(); i++)
        cout << '\t' << i->first << '-' << i->second << endl;

    t_myVec markedForDeath;

    for (t_myMap::const_iterator it = mi.begin(); it != mi.end() ; it++)
        if (it->first > 2 && it->first < 5)
            markedForDeath.push_back(it->first);

    for(size_t i = 0; i < markedForDeath.size(); i++)
        // old erase, returns void...
        mi.erase(markedForDeath[i]);

    cout << "after old style erase of 3 & 4.." << endl;
    for(t_myMap::const_iterator i = mi.begin(); i != mi.end(); i++)
        cout << '\t' << i->first << '-' << i->second << endl;

    for (auto it = mi.begin(); it != mi.end(); ) {
        if (it->first == 5)
            // new erase() that returns iter..
            it = mi.erase(it);
        else
            ++it;
    }

    cout << "after new style erase of 5" << endl;
    // new cend/cbegin and lambda..
    for_each(mi.cbegin(), mi.cend(), [](t_myMap::const_reference it){cout << '\t' << it.first << '-' << it.second << endl;});

    return 0;
}

prints:

main() ENTRY
Init
        1-1
        2-1
        3-1
        4-1
        5-1
        6-1
after old style erase of 3 & 4..
        1-1
        2-1
        5-1
        6-1
after new style erase of 5
        1-1
        2-1
        6-1

Process returned 0 (0x0)   execution time : 0.021 s
Press any key to continue.

Python Flask, how to set content type

from flask import Flask, render_template, make_response
app = Flask(__name__)

@app.route('/user/xml')
def user_xml():
    resp = make_response(render_template('xml/user.html', username='Ryan'))
    resp.headers['Content-type'] = 'text/xml; charset=utf-8'
    return resp

jQuery/JavaScript to replace broken images

This is JavaScript, should be cross browser compatible, and delivers without the ugly markup onerror="":

var sPathToDefaultImg = 'http://cdn.sstatic.net/stackexchange/img/logos/so/so-icon.png',
    validateImage = function( domImg ) {
        oImg = new Image();
        oImg.onerror = function() {
            domImg.src = sPathToDefaultImg;
        };
        oImg.src = domImg.src;
    },
    aImg = document.getElementsByTagName( 'IMG' ),
    i = aImg.length;

while ( i-- ) {
    validateImage( aImg[i] );
}

CODEPEN:

JavaScript alert box with timer

In short, the answer is no. Once you show an alert, confirm, or prompt the script no longer has control until the user returns control by clicking one of the buttons.

To do what you want, you will want to use DOM elements like a div and show, then hide it after a specified time. If you need to be modal (takes over the page, allowing no further action) you will have to do additional work.

You could of course use one of the many "dialog" libraries out there. One that comes to mind right away is the jQuery UI Dialog widget

How to set a cookie to expire in 1 hour in Javascript?

Code :

var now = new Date();
var time = now.getTime();
time += 3600 * 1000;
now.setTime(time);
document.cookie = 
'username=' + value + 
'; expires=' + now.toUTCString() + 
'; path=/';

Can I call jQuery's click() to follow an <a> link if I haven't bound an event handler to it with bind or click already?

Interesting, this is probably a "feature request" (ie bug) for jQuery. The jQuery click event only triggers the click action (called onClick event on the DOM) on the element if you bind a jQuery event to the element. You should go to jQuery mailing lists ( http://forum.jquery.com/ ) and report this. This might be the wanted behavior, but I don't think so.

EDIT:

I did some testing and what you said is wrong, even if you bind a function to an 'a' tag it still doesn't take you to the website specified by the href attribute. Try the following code:

<html>
<head>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>
 <script>
  $(document).ready(function() {
   /* Try to dis-comment this:
   $('#a').click(function () {
    alert('jQuery.click()');
    return true;
   });
   */
  });
  function button_onClick() {
   $('#a').click();
  }
  function a_onClick() {
   alert('a_onClick');
  }
 </script>

</head>
<body>
 <input type="button" onclick="button_onClick()">
 <br>
 <a id='a' href='http://www.google.com' onClick="a_onClick()"> aaa </a>

</body>
</html> 

It never goes to google.com unless you directly click on the link (with or without the commented code). Also notice that even if you bind the click event to the link it still doesn't go purple once you click the button. It only goes purple if you click the link directly.

I did some research and it seems that the .click is not suppose to work with 'a' tags because the browser does not suport "fake clicking" with javascript. I mean, you can't "click" an element with javascript. With 'a' tags you can trigger its onClick event but the link won't change colors (to the visited link color, the default is purple in most browsers). So it wouldn't make sense to make the $().click event work with 'a' tags since the act of going to the href attribute is not a part of the onClick event, but hardcoded in the browser.

Copying text to the clipboard using Java

This works for me and is quite simple:

Import these:

import java.awt.datatransfer.StringSelection;
import java.awt.Toolkit;
import java.awt.datatransfer.Clipboard;

And then put this snippet of code wherever you'd like to alter the clipboard:

String myString = "This text will be copied into clipboard";
StringSelection stringSelection = new StringSelection(myString);
Clipboard clipboard = Toolkit.getDefaultToolkit().getSystemClipboard();
clipboard.setContents(stringSelection, null);

Can anyone confirm that phpMyAdmin AllowNoPassword works with MySQL databases?

It works; just thought this would be helpful to someone in the future.

If you are working with MAMP, as a security measure, the $cfg['Servers'][$i]['AllowNoPassword'] = true; usually will be missing in the config.inc.php file so if you want to use phpMyAdmin without a password for root then simply add it preferably after the $cfg['Servers'][$i]['AllowDeny']['rules'] = array(); statement.

Then Restart your server just to be sure and you will be good to go.

why is plotting with Matplotlib so slow?

To start, Joe Kington's answer provides very good advice using a gui-neutral approach, and you should definitely take his advice (especially about Blitting) and put it into practice. More info on this approach, read the Matplotlib Cookbook

However, the non-GUI-neutral (GUI-biased?) approach is key to speeding up the plotting. In other words, the backend is extremely important to plot speed.

Put these two lines before you import anything else from matplotlib:

import matplotlib
matplotlib.use('GTKAgg') 

Of course, there are various options to use instead of GTKAgg, but according to the cookbook mentioned before, this was the fastest. See the link about backends for more options.

Find duplicate lines in a file and count how many time each line was duplicated?

To find duplicate counts use below command as requested by you :

sort filename | uniq -c | awk '{print $2, $1}'

How to get a jqGrid cell value when editing

I think a better solution than using getCell which as you know returns some html when in edit mode is to use jquery to access the fields directly. The problem with trying to parse like you are doing is that it will only work for input fields (not things like select), and it won't work if you have done some customizations to the input fields. The following will work with inputs and select elements and is only one line of code.

ondblClickRow: function(rowid) {
    var val = $('#' + rowid + '_MyCol').val();
}

How to set Linux environment variables with Ansible

There are multiple ways to do this and from your question it's nor clear what you need.

1. If you need environment variable to be defined PER TASK ONLY, you do this:

- hosts: dev
  tasks:
    - name: Echo my_env_var
      shell: "echo $MY_ENV_VARIABLE"
      environment:
        MY_ENV_VARIABLE: whatever_value

    - name: Echo my_env_var again
      shell: "echo $MY_ENV_VARIABLE"

Note that MY_ENV_VARIABLE is available ONLY for the first task, environment does not set it permanently on your system.

TASK: [Echo my_env_var] ******************************************************* 
changed: [192.168.111.222] => {"changed": true, "cmd": "echo $MY_ENV_VARIABLE", ... "stdout": "whatever_value"}

TASK: [Echo my_env_var again] ************************************************* 
changed: [192.168.111.222] => {"changed": true, "cmd": "echo $MY_ENV_VARIABLE", ... "stdout": ""}

Hopefully soon using environment will also be possible on play level, not only task level as above. There's currently a pull request open for this feature on Ansible's GitHub: https://github.com/ansible/ansible/pull/8651

UPDATE: It's now merged as of Jan 2, 2015.

2. If you want permanent environment variable + system wide / only for certain user

You should look into how you do it in your Linux distribution / shell, there are multiple places for that. For example in Ubuntu you define that in files like for example:

  • ~/.profile
  • /etc/environment
  • /etc/profile.d directory
  • ...

You will find Ubuntu docs about it here: https://help.ubuntu.com/community/EnvironmentVariables

After all for setting environment variable in ex. Ubuntu you can just use lineinfile module from Ansible and add desired line to certain file. Consult your OS docs to know where to add it to make it permanent.

How can I print a quotation mark in C?

you should use escape character like this:

printf("\"");

Converting binary to decimal integer output

I started working on this problem a long time ago, trying to write my own binary to decimal converter function. I don't actually know how to convert decimal to binary though! I just revisited it today and figured it out and this is what I came up with. I'm not sure if this is what you need, but here it is:

def __degree(number):
    power = 1

    while number % (10**power) != number:
        power += 1

    return power

def __getDigits(number):
    digits = []
    degree = __degree(number)

    for x in range(0, degree):
        digits.append(int(((number % (10**(degree-x))) - (number % (10**(degree-x-1)))) / (10**(degree-x-1))))
    return digits

def binaryToDecimal(number):
    list = __getDigits(number)
    decimalValue = 0
    for x in range(0, len(list)):
        if (list[x] is 1):
            decimalValue += 2**(len(list) - x - 1)
    return decimalValue

Again, I'm still learning Python just on my own, hopefully this helps. The first function determines how many digits there are, the second function actually figures out they are and returns them in a list, and the third function is the only one you actually need to call, and it calculates the decimal value. If your teacher actually wanted you to write your own converter, this works, I haven't tested it with every number, but it seems to work perfectly! I'm sure you'll all find the bugs for me! So anyway, I just called it like:

binaryNum = int(input("Enter a binary number: "))

print(binaryToDecimal(binaryNum))

This prints out the correct result. Cheers!

'module' object is not callable - calling method in another file

  • from a directory_of_modules, you can import a specific_module.py
  • this specific_module.py, can contain a Class with some_methods() or just functions()
  • from a specific_module.py, you can instantiate a Class or call functions()
  • from this Class, you can execute some_method()

Example:

#!/usr/bin/python3
from directory_of_modules import specific_module
instance = specific_module.DbConnect("username","password")
instance.login()

Excerpts from PEP 8 - Style Guide for Python Code:

Modules should have short and all-lowercase names.

Notice: Underscores can be used in the module name if it improves readability.

A Python module is simply a source file(*.py), which can expose:

  • Class: names using the "CapWords" convention.

  • Function: names in lowercase, words separated by underscores.

  • Global Variables: the conventions are about the same as those for Functions.

how to make label visible/invisible?

Change visible="false" to style="visibility:hidden" on your tags..


or better use a class to show/hide the labels..

.hidden{
   visibility:hidden;
}

then on your labels add class="hidden"

and with your script remove the class

document.getElementById("endTimeLabel").className = 'hidden'; // to hide

and

document.getElementById("endTimeLabel").className = ''; // to show

Django - Reverse for '' not found. '' is not a valid view function or pattern name

In my case, what I did was a mistake in the url tag in the respective template. So, in my url tag I had something like

{% url 'polls:details' question.id %}

while in the views, I had written something like:

def details(request, question_id): code here

So, the first thing you might wanna check is whether things are spelled as they shoould be. The next thing then you can do is as the people above have suggested.

Asyncio.gather vs asyncio.wait

A very important distinction, which is easy to miss, is the default bheavior of these two functions, when it comes to exceptions.


I'll use this example to simulate a coroutine that will raise exceptions, sometimes -

import asyncio
import random


async def a_flaky_tsk(i):
    await asyncio.sleep(i)  # bit of fuzz to simulate a real-world example

    if i % 2 == 0:
        print(i, "ok")
    else:
        print(i, "crashed!")
        raise ValueError

coros = [a_flaky_tsk(i) for i in range(10)]

await asyncio.gather(*coros) outputs -

0 ok
1 crashed!
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 20, in <module>
    asyncio.run(main())
  File "/Users/dev/.pyenv/versions/3.8.2/lib/python3.8/asyncio/runners.py", line 43, in run
    return loop.run_until_complete(main)
  File "/Users/dev/.pyenv/versions/3.8.2/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 17, in main
    await asyncio.gather(*coros)
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 12, in a_flaky_tsk
    raise ValueError
ValueError

As you can see, the coros after index 1 never got to execute.


But await asyncio.wait(coros) continues to execute tasks, even if some of them fail -

0 ok
1 crashed!
2 ok
3 crashed!
4 ok
5 crashed!
6 ok
7 crashed!
8 ok
9 crashed!
Task exception was never retrieved
future: <Task finished name='Task-10' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/xxx.py:6> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 12, in a_flaky_tsk
    raise ValueError
ValueError
Task exception was never retrieved
future: <Task finished name='Task-8' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/xxx.py:6> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 12, in a_flaky_tsk
    raise ValueError
ValueError
Task exception was never retrieved
future: <Task finished name='Task-2' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/xxx.py:6> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 12, in a_flaky_tsk
    raise ValueError
ValueError
Task exception was never retrieved
future: <Task finished name='Task-9' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/xxx.py:6> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 12, in a_flaky_tsk
    raise ValueError
ValueError
Task exception was never retrieved
future: <Task finished name='Task-3' coro=<a_flaky_tsk() done, defined at /Users/dev/PycharmProjects/trading/xxx.py:6> exception=ValueError()>
Traceback (most recent call last):
  File "/Users/dev/PycharmProjects/trading/xxx.py", line 12, in a_flaky_tsk
    raise ValueError
ValueError

Ofcourse, this behavior can be changed for both by using -

asyncio.gather(..., return_exceptions=True)

or,

asyncio.wait([...], return_when=asyncio.FIRST_EXCEPTION)


But it doesn't end here!

Notice: Task exception was never retrieved in the logs above.

asyncio.wait() won't re-raise exceptions from the child tasks until you await them individually. (The stacktrace in the logs are just messages, they cannot be caught!)

done, pending = await asyncio.wait(coros)
for tsk in done:
    try:
        await tsk
    except Exception as e:
        print("I caught:", repr(e))

Output -

0 ok
1 crashed!
2 ok
3 crashed!
4 ok
5 crashed!
6 ok
7 crashed!
8 ok
9 crashed!
I caught: ValueError()
I caught: ValueError()
I caught: ValueError()
I caught: ValueError()
I caught: ValueError()

On the other hand, to catch exceptions with asyncio.gather(), you must -

results = await asyncio.gather(*coros, return_exceptions=True)
for result_or_exc in results:
    if isinstance(result_or_exc, Exception):
        print("I caught:", repr(result_or_exc))

(Same output as before)

Understanding the main method of python

If you import the module (.py) file you are creating now from another python script it will not execute the code within

if __name__ == '__main__':
    ...

If you run the script directly from the console, it will be executed.

Python does not use or require a main() function. Any code that is not protected by that guard will be executed upon execution or importing of the module.

This is expanded upon a little more at python.berkely.edu

Finding child element of parent pure javascript

You have a parent element, you want to get all child of specific attribute 1. get the parent 2. get the parent nodename by using parent.nodeName.toLowerCase() convert the nodename to lower case e.g DIV will be div 3. for further specific purpose, get an attribute of the parent e.g parent.getAttribute("id"). this will give you id of the parent 4. Then use document.QuerySelectorAll(paret.nodeName.toLowerCase()+"#"_parent.getAttribute("id")+" input " ); if you want input children of the parent node

_x000D_
_x000D_
let parent = document.querySelector("div.classnameofthediv")_x000D_
let parent_node = parent.nodeName.toLowerCase()_x000D_
let parent_clas_arr = parent.getAttribute("class").split(" ");_x000D_
let parent_clas_str = '';_x000D_
  parent_clas_arr.forEach(e=>{_x000D_
     parent_clas_str +=e+'.';_x000D_
  })_x000D_
let parent_class_name = parent_clas_str.substr(0, parent_clas_str.length-1)  //remove the last dot_x000D_
let allchild = document.querySelectorAll(parent_node+"."+parent_class_name+" input")
_x000D_
_x000D_
_x000D_

How to open a URL in a new Tab using JavaScript or jQuery?

Use window.open():

var win = window.open('http://stackoverflow.com/', '_blank');
if (win) {
    //Browser has allowed it to be opened
    win.focus();
} else {
    //Browser has blocked it
    alert('Please allow popups for this website');
}

Depending on the browsers implementation this will work

There is nothing you can do to make it open in a window rather than a tab.

Best way to detect when a user leaves a web page?

I know this question has been answered, but in case you only want something to trigger when the actual BROWSER is closed, and not just when a pageload occurs, you can use this code:

window.onbeforeunload = function (e) {
        if ((window.event.clientY < 0)) {
            //window.localStorage.clear();
            //alert("Y coords: " + window.event.clientY)
        }
};

In my example, I am clearing local storage and alerting the user with the mouses y coords, only when the browser is closed, this will be ignored on all page loads from within the program.

Comparing a variable with a string python not working when redirecting from bash script

When you read() the file, you may get a newline character '\n' in your string. Try either

if UserInput.strip() == 'List contents': 

or

if 'List contents' in UserInput: 

Also note that your second file open could also use with:

with open('/Users/.../USER_INPUT.txt', 'w+') as UserInputFile:     if UserInput.strip() == 'List contents': # or if s in f:         UserInputFile.write("ls")     else:         print "Didn't work" 

How can I change the text color with jQuery?

Place the following in your jQuery mouseover event handler:

$(this).css('color', 'red');

To set both color and size at the same time:

$(this).css({ 'color': 'red', 'font-size': '150%' });

You can set any CSS attribute using the .css() jQuery function.

Center align with table-cell

This would be easier to do with flexbox. Using flexbox will let you not to specify the height of your content and can adjust automatically on the height it contains.

DEMO

here's the gist of the demo

.container{

  display: flex;
  height: 100%;
  justify-content: center;
  align-items: center;

}

html

<div class="container">
  <div class='content'> //you can size this anyway you want
    put anything you want here,
  </div>
</div>

enter image description here

How to move columns in a MySQL table?

phpMyAdmin provides a GUI for this within the structure view of a table. Check to select the column you want to move and click the change action at the bottom of the column list. You can then change all of the column properties and you'll find the 'move column' function at the far right of the screen.

Of course this is all just building the queries in the perfectly good top answer but GUI fans might appreciate the alternative.

my phpMyAdmin version is 4.1.7

jQuery select box validation

Since you cannot set value="" within your first option, you'll need to create your own rule using the built-in addMethod() method.

jQuery:

$(document).ready(function () {

    $('#myform').validate({ // initialize the plugin
        rules: {
            year: {
                selectcheck: true
            }
        }
    });

    jQuery.validator.addMethod('selectcheck', function (value) {
        return (value != '0');
    }, "year required");

});

HTML:

<select name="year">
    <option value="0">Year</option>
    <option value="1">1955</option>
    <option value="2">1956</option>
</select>

Working Demo: http://jsfiddle.net/tPRNd/


Original Answer: (Only if you can set value="" within the first option)

To properly validate a select element with the jQuery Validate plugin simply requires that the first option contains value="". So remove the 0 from value="0" and it's fixed.

jQuery:

$(document).ready(function () {

    $('#myform').validate({ // initialize the plugin
        rules: {
            year: {
                required: true,
            }
        }
    });

});

HTML:

<select name="year">
    <option value="">Year</option>
    <option value="1">1955</option>
    <option value="2">1956</option>
</select>

Demo: http://jsfiddle.net/XGtEr/

What is the difference between MySQL, MySQLi and PDO?

mysqli is the enhanced version of mysql.

PDO extension defines a lightweight, consistent interface for accessing databases in PHP. Each database driver that implements the PDO interface can expose database-specific features as regular extension functions.

Package structure for a Java project?

There are a few existing resources you might check:

  1. Properly Package Your Java Classes
  2. Spring 2.5 Architecture
  3. Java Tutorial - Naming a Package
  4. SUN Naming Conventions

For what it's worth, my own personal guidelines that I tend to use are as follows:

  1. Start with reverse domain, e.g. "com.mycompany".
  2. Use product name, e.g. "myproduct". In some cases I tend to have common packages that do not belong to a particular product. These would end up categorized according to the functionality of these common classes, e.g. "io", "util", "ui", etc.
  3. After this it becomes more free-form. Usually I group according to project, area of functionality, deployment, etc. For example I might have "project1", "project2", "ui", "client", etc.

A couple of other points:

  1. It's quite common in projects I've worked on for package names to flow from the design documentation. Usually products are separated into areas of functionality or purpose already.
  2. Don't stress too much about pushing common functionality into higher packages right away. Wait for there to be a need across projects, products, etc., and then refactor.
  3. Watch inter-package dependencies. They're not all bad, but it can signify tight coupling between what might be separate units. There are tools that can help you keep track of this.

How to write a simple Java program that finds the greatest common divisor between two numbers?

A recursive method would be:

static int gcd(int a, int b)
{
  if(a == 0 || b == 0) return a+b; // base case
  return gcd(b,a%b);
}

Using a while loop:

static int gcd(int a, int b)
{
  while(a!=0 && b!=0) // until either one of them is 0
  {
     int c = b;
     b = a%b;
     a = c;
  }
  return a+b; // either one is 0, so return the non-zero value
}

When I'm returning a+b, I'm actually returning the non-zero number assuming one of them is 0.

Read an Excel file directly from a R script

Another solution is the xlsReadWrite package, which doesn't require additional installs but does require you download the additional shlib before you use it the first time by :

require(xlsReadWrite)
xls.getshlib()

Forgetting this can cause utter frustration. Been there and all that...

On a sidenote : You might want to consider converting to a text-based format (eg csv) and read in from there. This for a number of reasons :

  • whatever your solution (RODBC, gdata, xlsReadWrite) some strange things can happen when your data gets converted. Especially dates can be rather cumbersome. The HFWutils package has some tools to deal with EXCEL dates (per @Ben Bolker's comment).

  • if you have large sheets, reading in text files is faster than reading in from EXCEL.

  • for .xls and .xlsx files, different solutions might be necessary. EG the xlsReadWrite package currently does not support .xlsx AFAIK. gdata requires you to install additional perl libraries for .xlsx support. xlsx package can handle extensions of the same name.

How to create timer in angular2

You can simply use setInterval utility and use arrow function as callback so that this will point to the component instance.

For ex:

this.interval = setInterval( () => { 
    // call your functions like 
    this.getList();
    this.updateInfo();
});

Inside your ngOnDestroy lifecycle hook, clear the interval.

ngOnDestroy(){
    clearInterval(this.interval);
}

How do the post increment (i++) and pre increment (++i) operators work in Java?

I believe you are executing all these statements differently
executing together will result => 38 ,29

int a=5,i;
i=++a + ++a + a++;
//this means i= 6+7+7=20 and when this result is stored in i,
//then last *a* will be incremented <br>
i=a++ + ++a + ++a;
//this means i= 5+7+8=20 (this could be complicated, 
//but its working like this),<br>
a=++a + ++a + a++;
//as a is 6+7+7=20 (this is incremented like this)

Split varchar into separate columns in Oracle

With REGEXP_SUBSTR is as simple as:

SELECT REGEXP_SUBSTR(t.column_one, '[^ ]+', 1, 1) col_one,
       REGEXP_SUBSTR(t.column_one, '[^ ]+', 1, 2) col_two
FROM YOUR_TABLE t;

Check time difference in Javascript

I have done some enhancements for timer counter

//example return : 01:23:02:02
//               : 1 Day 01:23:02:02
//               : 2 Days 01:23:02:02 


function get_timeDifference(strtdatetime) {
    var datetime = new Date(strtdatetime).getTime();
    var now = new Date().getTime();

    if (isNaN(datetime)) {
        return "";
    }

    //console.log(datetime + " " + now);

    if (datetime < now) {
        var milisec_diff = now - datetime;
    } else {
        var milisec_diff = datetime - now;
    }

    var days = Math.floor(milisec_diff / 1000 / 60 / (60 * 24));

    var date_diff = new Date(milisec_diff);





    var msec = milisec_diff;
    var hh = Math.floor(msec / 1000 / 60 / 60);
    msec -= hh * 1000 * 60 * 60;
    var mm = Math.floor(msec / 1000 / 60);
    msec -= mm * 1000 * 60;
    var ss = Math.floor(msec / 1000);
    msec -= ss * 1000


    var daylabel = "";
    if (days > 0) {
        var grammar = " ";
        if (days > 1) grammar = "s " 
        var hrreset = days * 24;
        hh = hh - hrreset;
        daylabel = days + " Day" + grammar ;
    }


    //  Format Hours
    var hourtext = '00';
    hourtext = String(hh);
    if (hourtext.length == 1) { hourtext = '0' + hourtext };

    //  Format Minutes
    var mintext = '00';
    mintext = String(mm); 
    if (mintext.length == 1) { mintext = '0' + mintext };

    //  Format Seconds
    var sectext = '00';
    sectext = String(ss); 
    if (sectext.length == 1) { sectext = '0' + sectext };

    var msectext = '00';
    msectext = String(msec);
    msectext = msectext.substring(0, 1);
    if (msectext.length == 1) { msectext = '0' + msectext };

    return daylabel + hourtext + ":" + mintext + ":" + sectext + ":" + msectext;
}

Generator expressions vs. list comprehensions

Sometimes you can get away with the tee function from itertools, it returns multiple iterators for the same generator that can be used independently.

How to add 30 minutes to a JavaScript Date object?

Maybe something like this?

_x000D_
_x000D_
var d = new Date();_x000D_
var v = new Date();_x000D_
v.setMinutes(d.getMinutes()+30);_x000D_
_x000D_
console.log(v)
_x000D_
_x000D_
_x000D_

Using ListView : How to add a header view?

You simply can't use View as a Header of ListView.

Because the view which is being passed in has to be inflated.

Look at my answer at Android ListView addHeaderView() nullPointerException for predefined Views for more info.

EDIT:

Look at this tutorial Android ListView and ListActivity - Tutorial .

EDIT 2: This link is broken Android ListActivity with a header or footer

How to hide TabPage from TabControl

private System.Windows.Forms.TabControl _tabControl;
private System.Windows.Forms.TabPage _tabPage1;
private System.Windows.Forms.TabPage _tabPage2;

...
// Initialise the controls
...

// "hides" tab page 2
_tabControl.TabPages.Remove(_tabPage2);

// "shows" tab page 2
// if the tab control does not contain tabpage2
if (! _tabControl.TabPages.Contains(_tabPage2))
{
    _tabControl.TabPages.Add(_tabPage2);
}

How to create a vector of user defined size but with no predefined values?

With the constructor:

// create a vector with 20 integer elements
std::vector<int> arr(20);

for(int x = 0; x < 20; ++x)
   arr[x] = x;

Regular Expression to select everything before and up to a particular text

This matches everything up to ".txt" (without including it):

^.*(?=(\.txt))

plot data from CSV file with matplotlib

According to the docs numpy.loadtxt is

a fast reader for simply formatted files. The genfromtxt function provides more sophisticated handling of, e.g., lines with missing values.

so there are only a few options to handle more complicated files. As mentioned numpy.genfromtxt has more options. So as an example you could use

import numpy as np
data = np.genfromtxt('e:\dir1\datafile.csv', delimiter=',', skip_header=10,
                     skip_footer=10, names=['x', 'y', 'z'])

to read the data and assign names to the columns (or read a header line from the file with names=True) and than plot it with

ax1.plot(data['x'], data['y'], color='r', label='the data')

I think numpy is quite well documented now. You can easily inspect the docstrings from within ipython or by using an IDE like spider if you prefer to read them rendered as HTML.

What does set -e mean in a bash script?

I found this post while trying to figure out what the exit status was for a script that was aborted due to a set -e. The answer didn't appear obvious to me; hence this answer. Basically, set -e aborts the execution of a command (e.g. a shell script) and returns the exit status code of the command that failed (i.e. the inner script, not the outer script).

For example, suppose I have the shell script outer-test.sh:

#!/bin/sh
set -e
./inner-test.sh
exit 62;

The code for inner-test.sh is:

#!/bin/sh
exit 26;

When I run outer-script.sh from the command line, my outer script terminates with the exit code of the inner script:

$ ./outer-test.sh
$ echo $?
26

Installing specific package versions with pip

Since this appeared to be a breaking change introduced in version 10 of pip, I downgraded to a compatible version:

pip install 'pip<10' 

This command tells pip to install a version of the module lower than version 10. Do this in a virutalenv so you don't screw up your site installation of Python.

Print text in Oracle SQL Developer SQL Worksheet window

enter image description here

for simple comments:

set serveroutput on format wrapped;
begin
    DBMS_OUTPUT.put_line('simple comment');
end;
/

-- do something

begin
    DBMS_OUTPUT.put_line('second simple comment');
end;
/

you should get:

anonymous block completed
simple comment

anonymous block completed
second simple comment

if you want to print out the results of variables, here's another example:

set serveroutput on format wrapped;
declare
a_comment VARCHAR2(200) :='first comment';
begin
    DBMS_OUTPUT.put_line(a_comment);
end;

/

-- do something


declare
a_comment VARCHAR2(200) :='comment';
begin
    DBMS_OUTPUT.put_line(a_comment || 2);
end;

your output should be:

anonymous block completed
first comment

anonymous block completed
comment2