PHP IF VARIABLE is not equal to variable code example

Example 1: 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.

Example 2: php ?:

// Example usage for: Ternary Operator
$action = $_POST['action'] ?: 'default';

// The above is identical to this if/else statement
if (empty($_POST['action'])) {
    $action = 'default';
} else {
    $action = $_POST['action'];
}