What does "===" mean?

Question

I've noticed someone using the PHP operator === which I can't make sense out of. I've tried it with a function, and it corresponds in crazy ways.

What is the definition of this operator? I can't even find it in the declaration of PHP operators.

Solution 1

$a === $b     (Identical)      

TRUE if $a is equal to $b, and they are of the same type. (introduced in PHP 4)

PHP Docs

Solution 2

http://www.php.net/ternary

$a == $b Equal TRUE if $a is equal to $b, except for (True == -1) which is still True.

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

> "5" == 5;
True
> "5" === 5;
False

Solution 3

In PHP you may compare two values using the == operator or === operator. The difference is this:

PHP is a dynamic, interpreted language that is not strict on data types. It means that the language itself will try to convert data types, whenever needed.

echo 4 + "2"; // output is 6

The output is integer value 6, because + is the numerical addition operator in PHP, so if you provide operands with other data types to it, PHP will first convert them to their appropriate type ("2" will be converted to 2) and then perform the operation.

If you use == as the comparison operator with two operands that might be in different data types, PHP will convert the second operand type, to the first's. So:

4 == "4" // true

PHP converts "4" to 4, and then compares the values. In this case, the result will be true.

If you use === as the comparison operator, PHP will not try to convert any data types. So if the operands' types are different, then they are NOT identical.

4 === "4" // false

Solution 4

You can read here, short summary:

$a == $b Equal TRUE if $a is equal to $b after type juggling.

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

Solution 5

$x == $y is TRUE if the value of the $x and $y are same:

$x = 1; //int type
$y = "1"; //string type
if ($x == $y) {
    // This will execute
}

$x === $y TRUE if the value of the $x and $y are same and type of $x and $y are same:

$x = 1; //int type
$y = "1"; //string type
if ($x === $y) {
    // This will not execute
}

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