php != operator
$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. $a != $b Not equal TRUE if $a is not equal to $b after type juggling. $a <> $b Not equal TRUE if $a is not equal to $b after type juggling. $a !== $b Not identical TRUE if $a is not equal to $b, or they are not of the same type. $a < $b Less than TRUE if $a is strictly less than $b. $a > $b Greater than TRUE if $a is strictly greater than $b. $a <= $b Less than or equal to TRUE if $a is less than or equal to $b. $a >= $b Greater than or equal to TRUE if $a is greater than or equal to $b. $a <=> $b Spaceship An integer less than, equal to, or greater than zero when $a is less than, equal to, or greater than $b, respectively. Available as of PHP 7.
