Simple comparison of is_null($x) and $x === null in PHP

In PHP, both is_null($x) and $x === null can be used to determine whether the value of variable $x is "NULL", so what is the difference between them? The following article will introduce you to the is_null() and === null methods, and briefly compare these two methods. I hope it will be helpful to everyone.

is_null() function

is_null() is a built-in function in PHP for Find if a variable is NULL. Returns True if the given variable is null, False otherwise.

Note: Null is a special data type in PHP and can only have one NULL value. A variable of data type NULL represents a variable that has not yet been assigned a value. Any variable can be made null by setting its value to NULL.

Basic sentence structure:

is_null（$var）

Example:

<?php 
$array =array(false, NULL, 15, 0 ); 
for($i=0;$i<4;$i++){
var_dump(is_null($array[$i])); 
}
?>

Output:

=== null

=== null is the same comparison operator. If the value on the left side of "===" is equal to null, return true, otherwise Return false. Example: $x === null, if the value of $x is equal to NULL, return true.

Basic sentence structure:

$var === null

Example:

<?php 
$array =array(false, NULL, 15, 0 ); 
for($i=0;$i<4;$i++){
if ($array[$i] === null) {
echo "True <br>"; 
}
    else 
    echo "False <br>"; 
}
?>

Output:

Conclusion:

is_null() is a function, and === null is a comparison operator. Therefore, is_null() is slightly slower (function call overhead), but is_null() can be used as a callback. Which method to choose to determine whether the value is "null" needs to be based on actual needs.

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