How to verify a datatype mismatch? (not=== false)

Question

What's the opposite of triple equals matching in PHP?

$mail_01 = filter_var($mail_01, FILTER_VALIDATE_EMAIL);
if($mail !== false){
    echo "Email address required";
}

Is the !== usage correct? Thanks for any help.

Answer 1

Yes, !== is correct. From the manual:

$a !== $b Not identical
TRUE if $a is not equal to $b, or they are not of the same type. (introduced in PHP 4)

Answer 2

Yes, this is correct. See the PHP manual

Answer 3

Yes, that's correct. a !== b is logically equivalent to !(a === b).