What is the "===" operator for?

I once encountered an operator "===". But I don remember what it was.. or where do we use it .. or is t开发者_JAVA技巧here any such a kind of operator ? where is it used ??

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In PHP, JavaScript, ECMAScript, ActionScript 3.0, and a number of other similar, dynamic languages, there are two types of equality checks: == (non-strict equality) and === (strict equality). To show an example:

5 == "5"   // yep, these are equal, because "5" becomes 5 when converted to int
5 === "5"  // nope, these have a different type

Basically, whenever you use ==, you risk automatic type conversions. Using === ensures that the values are logically equal AND the types of the objects are also equal.

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In JavaScript, == does type coercion, while ===, the "strict equality" operator does not. For example:

"1" == 1; // true
"1" === 1; // false

There is also a corresponding strict inequality operator, !==.

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Its used in JavaScript, PHP and may be more (which I may not have encountered yet!), it is used to compare if both the compared things are of same object type as well as have same value.

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"===" operator is used to check the values are equal as well as same type.

Example

$a === $b    if $a is equal to $b, and they are of the same type.

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It usually tests if two objects are the same. ie. not if they have the same value(s) but if they really are the same object.

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=== is equality, at least in PHP

Here is a link that helps explain thsi

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In Ruby, triple equals is the operator (implicitly) used by the case/when construct to determine when an object "falls within" a particular case. For example, Ruby has a concept of "Range" objects; 1..10 means "all of the values between 1 and 10, inclusive." So `3 == 1..10' is false, since the 3 is a number and the 1..10 is a Range. But,

3 === 1..10 returns true, since 3 is in that range.

case/when uses this when deciding which case an arguments belongs to. So,

case a
  when (1..10)
    puts "This is a valid rating"
  else
    puts "invalid"
  end

works as expected.