What does !== comparison operator in PHP mean?

 

I saw 

if($output !== false){
}

It's an exclamation mark with two equals signs.

It almost works like not equal. Does it has any extra significance?

They are the strict equality operators ( ===, !==) , the two operands must have the same type and value in order the result to be true.

For example: 

var_dump(0 == "0"); //  true
var_dump("1" == "01"); //  true
var_dump("1" == true); //  true

var_dump(0 === "0"); //  false
var_dump("1" === "01"); //  false
var_dump("1" === true); //  false

More information:

  • PHP Comparison Operators

    • PHP's === Operator enables you to compare or test variables for both equality and type.

    So !== is (not ===)

    !== checks the type of the variable as well as the value. So for example, 

    $a = 1;
$b = '1';
if ($a != $b) echo 'hello';
if ($a !== $b) echo 'world';

    will output just 'world', as $a is an integer and $b is a string.

    You should check out the manual page on PHP operators, it's got some good explanations.

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