NULL COALESCING OPERATOR
The null coalescing operator (??) has been added as syntactic sugar for the common case of needing to use a ternary in conjunction with isset(). It returns its first operand if it exists and is not
NULL; otherwise it returns its second operand.
// Coalescing can be chained: this will return the first
// Fetches the value of $_GET['user'] and returns 'nobody'
// if it does not exist.
$username = $_GET['user'] ?? 'nobody';// This is equivalent to:
$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';
// defined value out of $_GET[‘user’], $_POST[‘user’], and
$username = $_GET[‘user’] ?? $_POST[‘user’] ?? ‘nobody’;