Take a look at &lt;a href=&quot;http://www.ecma-international.org/ecma-262/5.1/#sec-12.11&quot;&gt;ECMA 262, section 12.11&lt;/a&gt;, the second algorithm, 4.c.

&gt; _c.	If input is equal to clauseSelector as defined by the === operator, then..._

http://qfox.nl/notes/110 answers your question. (This guy knows a lot about the nitty gritty of JavaScript)

&gt; Switches in Javascript use strict type checking (===). So you never
&gt; have to worry about coercion, which prevents a few wtfjs :). If on the
&gt; other hand you were counting on coercion, tough luck because you can&#39;t
&gt; force it.

Yes, `switch` &quot;[uses] the strict comparison, `===`&quot;.

Source: [switch - JavaScript | MDN][1]


  [1]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/switch

I am just wondering, if I want to divide a by b, and am interested both in the result c and the remainder (e.g. say I have number of seconds and want to split that into minutes and seconds), what is the best way to go about it?

Would it be

    int c = (int)a / b;
    int d = a % b;

or

    int c = (int)a / b;
    int d = a - b * c;

or

    double tmp = a / b;
    int c = (int)tmp;
    int d = (int)(0.5+(tmp-c)*b);

or

maybe there is a magical function that gives one both at once?
  

C++ Best way to get integer division and remainder

How do you check if it is open or closed I was using

     if (SQLOperator.SQLCONNECTION.State.Equals(&quot;Open&quot;))

however, even the State is &#39;Open&#39; it fails on this check.


Check if SQL Connection is Open or Closed

I have a variable that can either be boolean `false`, or an integer (including 0). I want to put it in a switch statement like:

    switch(my_var){
        case 0:
             // Do something
             break;
        case 1:
             // Do something else
             break;
        case false:
             // Some other code
    }

In my tests in Google Chrome, it seems to work perfectly, but I&#39;m a little nervous to use it because I&#39;m afraid that in some browsers, if `my_var` is `false`, it might execute the first case since `0 == false`.

I&#39;m just wondering if there is anything official in JavaScript that says the switch statement will use strict comparison such that `0 !== false`, but I can&#39;t find anything myself, and I&#39;m not sure if this will work well in different JavaScript engines. Does anybody know if the comparison done by a switch statement is guaranteed to be strict?

Is it safe to assume strict comparison in a JavaScript switch statement?

I have a variable that can either be boolean <code>false</code>, or an integer (including 0). I want to put it in a switch statement like:
<pre><code class="hljs language-arduino">switch(my_var){
 case 0:
 // Do something
 break;
 case 1:
 // Do something else
 break;
 case false:
 // Some other code
}
</code></pre>
In my tests in Google Chrome, it seems to work perfectly, but I'm a little nervous to use it because I'm afraid that in some browsers, if <code>my_var</code> is <code>false</code>, it might execute the first case since <code>0 == false</code>.
I'm just wondering if there is anything official in JavaScript that says the switch statement will use strict comparison such that <code>0 !== false</code>, but I can't find anything myself, and I'm not sure if this will work well in different JavaScript engines. Does anybody know if the comparison done by a switch statement is guaranteed to be strict?

I need to get the ID of an element but the value is dynamic with only the beginning of it is the same always. 

Heres a snippet of the code.

    &lt;form class=&quot;form-poll&quot; id=&quot;poll-1225962377536&quot; action=&quot;/cs/Satellite&quot;&gt;

The ID always starts with `poll-` then the numbers are dynamic.

How can I get the ID using just JavaScript and not jQuery?

Javascript getElementById based on a partial string

Currently, most of the popular websites, like google, yahoo detect if the user connection speed is slow and then give a option to load basic version of the website instead of the high end one.

What are the methods available to detect slow internet connections?

&lt;sub&gt;P.S. I think this is achieved through javascript, so I will tag it as a javascript question? However, I am looking for answers oriented more towards PHP, if this is also server related.&lt;/sub&gt;

How to detect slow internet connections?

I&#39;m writing a simple server for Node.js and I&#39;m using my own class called `User` which looks like:
    
    function User(socket) {
        this.socket = socket;
        this.nickname = null;

        /* ... just the typical source code like functions, variables and bugs ... */

        this.write = function(object) {
            this.socket.write(JSON.stringify(object));
        }
    };

and then later in the process I&#39;m instantiating it a lot:

    var server = net.createServer(function (socket) {
        /* other bugs */
        var user = new User(socket);
        /* more bugs and bad practise */
    });

Can I move my `User` class definition to another javascript file and &quot;include&quot; it somehow?

Including JavaScript class definition from another file in Node.js

How to detect Firefox in JavaScript?&lt;br /&gt;
I want to detect all versions of Firefox.

Detect all Firefox versions in JS

In multiple browsers, the following code doesn&#39;t sort the numbers correctly:

    a = new Array();
    a.push(10);
    a.push(60);
    a.push(20);
    a.push(30);
    a.push(100);
    document.write(a.sort())

It returns `10,100,20,30,60`.

Anyone know why?

How to sort numbers correctly with Array.sort()?

I often seen the symbol `1L` (or `2L`, `3L`, etc) appear in R code.  Whats the difference between `1L` and `1`?  `1==1L` evaluates to `TRUE`.   Why is `1L` used in R code?

What&#39;s the difference between `1L` and `1`?

Suppose I&#39;m trying to write a function to return an instance of the current type. Is there a way to make `T` refer to the exact subtype (so `T` should refer to `B` in class `B`)?

    class A {
        &lt;T extends A&gt; foo();
    }
    
    class B extends A {
        @Override
        T foo();
    }

Is there a way to refer to the current type with a type variable?

Is there a better way to get the type of a variable in JS than `typeof`? It works fine when you do:

    &gt; typeof 1
    &quot;number&quot;
    &gt; typeof &quot;hello&quot;
    &quot;string&quot;

But it&#39;s useless when you try:
    
    &gt; typeof [1,2]
    &quot;object&quot;
    &gt;r = new RegExp(/./)
    /./
    &gt; typeof r
    &quot;function&quot;

I know of `instanceof`, but this requires you to know the type beforehand.    

    &gt; [1,2] instanceof Array
    true
    &gt; r instanceof RegExp
    true

Is there a better way?

Better way to get type of a Javascript variable?

Coming back to Scala after a spell writing Haskell, I&#39;ve started using the type keyword to make my class definitions a bit more readable, eg:

    type RestfulParams = Map[String, String]
    def canonicalize(params: RestfulParams): String = { ... }

The trouble I&#39;ve run into is that these type definitions need to live inside a class or object - they&#39;re not &quot;first class citizens&quot; like they are in Haskell. If I try to define a type outside of a class or object, I get a compiler `expected class or object definition`.

My problem then is how to use these types across multiple classes and objects in a package? What I&#39;ve done now seems quite ugly:

    object RestfulTypes { type RestfulParams = Map[String, String] etc }

And then in another class file:

    import utils.{RestfulTypes =&gt; RT}
    def get(resource: String, params: RT.RestfulParams): String = { ... }

Is there a nicer way of doing this - and incidentally do the Scala gurus think it&#39;s a good thing or a bad thing that types can only be defined inside classes/objects?

Scala type keyword: how best to use it across multiple classes

I just wrote a tiny method to count the number of pages for cell phone SMS. I didn&#39;t have the option to round up using `Math.ceil`, and honestly it seems to be very ugly.

Here is my code:

    public class Main {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
       String message = &quot;today we stumbled upon a huge performance leak while optimizing a raycasting algorithm. Much to our surprise, the Math.floor() method took almost half of the calculation time: 3 floor operations took the same amount of time as one trilinear interpolation. Since we could not belive that the floor-method could produce such a enourmous overhead, we wrote a small test program that reproduce&quot;;
       
       System.out.printf(&quot;COunt is %d &quot;,(int)messagePageCount(message));
       
       
       
    }

    public static double messagePageCount(String message){
        if(message.trim().isEmpty() || message.trim().length() == 0){
            return 0;
        } else{
            if(message.length() &lt;= 160){
                return 1;
            } else {
                return Math.ceil((double)message.length()/153);
            }
        }
    }

I don&#39;t really like this piece of code and I&#39;m looking for a more elegant way of doing this. With this, I&#39;m expecting 3 and not 3.0000000. Any ideas?

How to round up integer division and have int result in Java?

I&#39;ve always coded in the style of `if not value`, however, a few guides have brought to my attention that while this style works, it seems to have 2 potential problems:

1. It&#39;s not completely readable; `if value is None` is surely more understandable.
2. This can have implications later (and cause subtle bugs), since things like `[]` and `0` will evaluate to `False` as well.

I am also starting to apply this idea to other comparisons, such as:

* `if not value` vs `if value is False`
* `if not value` vs `if value is []`

And so goes the list...

The question is, how far do you go with the principle? Where to draw the line, while keeping your code safe?

Should I always use the `if value is None` style no matter what?

Python: if not val, vs if val is None

I am trying to understand the difference between these four methods. I know by default that `==` calls the method `equal?` which returns true when both operands refer to exactly the same object.

`===` by default also calls `==` which calls `equal?`... okay, so if all these three methods are not overridden, then I guess
`===`, `==` and `equal?` do exactly the same thing?

Now comes `eql?`. What does this do (by default)? Does it make a call to the operand&#39;s hash/id? 

Why does Ruby have so many equality signs? Are they supposed to differ in semantics?


What&#39;s the difference between equal?, eql?, ===, and ==?

I work with a lot of calculation code written in [tag:C++] with high-performance and low memory overhead in mind. It uses STL containers (mostly `std::vector`) a lot, and iterates over that containers almost in every single function.

The iterating code looks like this:

    for (int i = 0; i &lt; things.size(); ++i)
    {
        // ...
    }

But it produces the **signed/unsigned mismatch** warning (**C4018 in Visual Studio**).

Replacing `int` with some `unsigned` type is a problem because we frequently use `OpenMP` pragmas, and it requires the counter to be `int`.

I&#39;m about to suppress the (hundreds of) warnings, but I&#39;m afraid I&#39;ve missed some elegant solution to the problem.

**On iterators**. I think iterators are great when applied in appropriate places. The code I&#39;m working with will _never_ change random-access containers into `std::list` or something (so iterating with `int i` is already container agnostic), and will _always_ need the current index. And all the additional code you need to type (iterator itself and the index) just complicates matters and obfuscates the simplicity of the underlying code.

How do I deal with &quot;signed/unsigned mismatch&quot; warnings (C4018)?

The line of code `DateTime d = DateTime.Today;` results in `10/12/2011 12:00:00 AM`. How can I get only the date part.I need to ignore the time part when I compare two dates. 


extract the date part from DateTime in C#


    a = [1, 2, 3, 1, 2, 3]
    b = [3, 2, 1, 3, 2, 1]

a &amp; b should be considered equal, because they have exactly the same elements, only in different order.

The thing is, my actual lists will consist of objects (my class instances), not integers.


How to efficiently compare two unordered lists (not sets) in Python?

I have an array:

    $a = array(&#39;foo&#39; =&gt; &#39;fooMe&#39;);

and I do:

    print_r($a);

which prints:

    Array ( [foo] =&gt; printme )

Is there a function, so when doing:

    needed_function(&#39;    Array ( [foo] =&gt; printme )&#39;);

I will get the array `array(&#39;foo&#39; =&gt; &#39;fooMe&#39;);` back?

How create an array from the output of an array printed with print_r?

With ARC, I can no longer cast `CGColorRef` to `id`. I learned that I need to do a bridged cast. According [clang docs][1]:

&gt; A **bridged cast** is a C-style cast annotated with one of three keywords:
&gt; 
&gt; `(__bridge T) op` casts the operand to the destination type `T`. If `T`
&gt; is a retainable object pointer type, then `op` must have a
&gt; non-retainable pointer type. If `T` is a non-retainable pointer type,
&gt; then op must have a retainable object pointer type. Otherwise the cast
&gt; is ill-formed. There is no transfer of ownership, and ARC inserts no
&gt; retain operations.
&gt;
&gt; `(__bridge_retained T) op` casts the operand, which must have
&gt; retainable object pointer type, to the destination type, which must be
&gt; a non-retainable pointer type. ARC retains the value, subject to the
&gt; usual optimizations on local values, and the recipient is responsible
&gt; for balancing that +1.
&gt; 
&gt; `(__bridge_transfer T) op` casts the operand, which must have
&gt; non-retainable pointer type, to the destination type, which must be a
&gt; retainable object pointer type. ARC will release the value at the end
&gt; of the enclosing full-expression, subject to the usual optimizations
&gt; on local values.
&gt; 
&gt; These casts are required in order to transfer objects in and out of
&gt; ARC control; see the rationale in the section on conversion of
&gt; retainable object pointers.
&gt; 
&gt; Using a `__bridge_retained` or `__bridge_transfer` cast purely to convince
&gt; ARC to emit an unbalanced retain or release, respectively, is poor
&gt; form.

In what kind of situations would I use each?

For example, `CAGradientLayer` has a `colors` property which accepts an array of `CGColorRef`s. My guess is that I should use `__brige` here, but exactly why I should (or should not) is unclear.

  [1]: http://clang.llvm.org/docs/AutomaticReferenceCounting.html#bridged-casts

ARC and bridged cast

I am trying to verify whether a variable that is passed can be converted to a specific type.  I have tried the following but can&#39;t get it to compile so I assume I&#39;m going about it the wrong way (I&#39;m new to C#)

    string myType = &quot;System.Int32&quot;;
    string myValue = &quot;42&quot;;
    
    bool canBeCast = false;
    
    try
    {
      // try to convert the value to it&#39;s intended type to see if it&#39;s valid.
      var result = (Type.GetType(typeString))dataValue;
      canBeCast = true;
    }
    catch
    {
      canBeCast = false;
    }

I&#39;m basically trying to avoid a massive switch statement along the lines of

      switch(myType){
        case &quot;System.Int32&quot;:
          try
          {
            var convertedValue = Convert.ToInt32(myValue);
          }
          catch (Exception)
          {
            canBeConverted = false;
          }
          break;
        case &quot;another type&quot;:
          ...
      }

EDIT:

Ok, basically I have a db table of known input types that looks like:

    CREATE TABLE [dbo].[MetadataTypes] (
        [typeName]  VARCHAR (50)  NOT NULL,
        [dataType]  VARCHAR (50)  NOT NULL,
        [typeRegex] VARCHAR (255) NULL
    );

which may have data such as 

    &quot;StartTime&quot;,&quot;System.DateTime&quot;,null
    &quot;TicketId&quot;,&quot;System.String&quot;,&quot;$[Ff][0-9]{7}^&quot;

And the input to my function would be a KeyValuePair&lt;string,string&gt; along the lines of 

    myInput = new KeyValuePair&lt;string,string&gt;(&quot;StartTime&quot;,&quot;31/12/2010 12:00&quot;);

I need to check that the value of the KeyValuePair is of the correct datatype expected by the MetaDataType.


EDIT FOR ANSWER:

Leon got really close to the solution I finally came up with.

For reference my function now looks like this:

    public Boolean ValidateMetadata(KeyValuePair&lt;string, string&gt; dataItem)
    {

      // Look for known metadata with name match
      MetadataType type = _repository.GetMetadataTypes().SingleOrDefault(t =&gt; t.typeName == dataItem.Key);
      if (type == null) { return false; }

      // Get the data type and try to match to the passed in data item.
      Boolean isCorrectType = false;
      string typeString = type.dataType;
      string dataValue = dataItem.Value;

      try
      {
        var cValue = Convert.ChangeType(dataValue, Type.GetType(typeString));
        isCorrectType = true;
      }
      catch
      {
        isCorrectType = false;
      }

      //TODO: Validate against possible regex here....            
            
      return isCorrectType;

    }


Can I check if a variable can be cast to a specified type?

I have a dataframe such as:

    a1 = c(1, 2, 3, 4, 5)
    a2 = c(6, 7, 8, 9, 10)
    a3 = c(11, 12, 13, 14, 15)
    aframe = data.frame(a1, a2, a3)

I tried the following to convert one of the columns to a vector, but it doesn&#39;t work:

    avector &lt;- as.vector(aframe[&#39;a2&#39;])
    class(avector) 
    [1] &quot;data.frame&quot;

This is the only solution I could come up with, but I&#39;m assuming there has to be a better way to do this:

    class(aframe[&#39;a2&#39;]) 
    [1] &quot;data.frame&quot;
    avector = c()
    for(atmp in aframe[&#39;a2&#39;]) { avector &lt;- atmp }
    class(avector)
    [1] &quot;numeric&quot;

**Note:** My vocabulary above may be off, so please correct me if so.  I&#39;m still learning the world of R.  Additionally, any explanation of what&#39;s going on here is appreciated (i.e. relating to Python or some other language would help!)


Convert data.frame column to a vector?

I have a table containing latitude and longitude values stored as strings (`VARCHAR`) which I&#39;d like to convert to `FLOAT (10,6)`.

However there doesn&#39;t appear to be a straightforward way to do this using `CAST()` or `CONVERT()`.

How can I convert these columns easily? This is a one-time conversion.

How can I convert a string to a float in mysql?

I&#39;m doing an C# app where I use 

    if ((message.Contains(&quot;test&quot;)))
    {
       Console.WriteLine(&quot;yes&quot;);
    } else if ((message.Contains(&quot;test2&quot;))) {
       Console.WriteLine(&quot;yes for test2&quot;);
    }

There would be any way to change to `switch()` the `if()` statements?


Use string.Contains() with switch()

&gt; **Possible Duplicate:**  
&gt; [C# - Is there a better alternative than this to &amp;#39;switch on type&amp;#39;?](https://stackoverflow.com/questions/298976/c-sharp-is-there-a-better-alternative-than-this-to-switch-on-type)  

&lt;!-- End of automatically inserted text --&gt;

Hello suppose i get a big if/else on class type. it&#39;s there a way to do it with a switch case ?

Example :

    function test(object obj)
    {
    if(obj is WebControl)
    {
    
    }else if(obj is TextBox)
    {
    
    }
    else if(obj is ComboBox)
    {
    
    }


etc ...

I would like to create something like 

    switch(obj)
    {
    case is TextBox:
    break;
    case is ComboBox:
    break;
    
    }


}

Switch case on type c#

Is there a way to assign two different case values to the same block of code without copy and pasting? For example, below 68 and 40 should execute the same code, while 30 is not related.

    case 68:
       //Do something
    break;

    case 40:
       //Do the same thing
    break;
   
    case 30:
       //Do something different
    break;
 
Is it incorrect to think something like this should work (even though it obviously doesn&#39;t)?

    case 68 || 40:
       //Do something
    break;

    case 30:
       //Do something else
    break;

JavaScript, Typescript switch statement: way to run same code for two cases?

My code is as follows:

    public static void Output&lt;T&gt;(IEnumerable&lt;T&gt; dataSource) where T : class
    {   
        dataSourceName = (typeof(T).Name);
        switch (dataSourceName)
        {
            case (string)typeof(CustomerDetails).Name.ToString(); :
                var t = 123;
                break;
            default:
                Console.WriteLine(&quot;Test&quot;);
        }
    }

But this is not working. The case statement is giving me an error saying that a constant variable is expected. Please help guys thank you!

Switch case in C# - a constant value is expected

I am a little confused about the switch statement in R. 
Simply googling the function I get an example as follows:

A common use of switch is to branch according to the character value of one of the arguments to a function.

     &gt; centre &lt;- function(x, type) {
     + switch(type,
     +        mean = mean(x),
     +        median = median(x),
     +        trimmed = mean(x, trim = .1))
     + }
     &gt; x &lt;- rcauchy(10)
     &gt; centre(x, &quot;mean&quot;)
     [1] 0.8760325
     &gt; centre(x, &quot;median&quot;)
     [1] 0.5360891
     &gt; centre(x, &quot;trimmed&quot;)
     [1] 0.6086504

However this just seems to be the same as just having a bunch of `if` statements designated for each `type`

Is that all there is to `switch()`? Can someone give me further examples and better applications?

Content Type	Original Author	Original Content on Stackoverflow
Question	Paul	View Question on Stackoverflow
Solution 1 - Javascript	Federico Lebrón	View Answer on Stackoverflow
Solution 2 - Javascript	Halcyon	View Answer on Stackoverflow
Solution 3 - Javascript	ma11hew28	View Answer on Stackoverflow

Is it safe to assume strict comparison in a JavaScript switch statement?

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Solution 2 - Javascript

Solution 3 - Javascript

Check if SQL Connection is Open or Closed

C++ Best way to get integer division and remainder

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