php null coalesce
// if $_POST['name'] doesn't exist $result will equal to John
$result = $_POST['name'] ?? 'John';
null Koalescenčný operátor php
// The null coalescing operator (??) is used to replace the ternary operation
// in conjunction with isset() function and returns its first operand if it
// exists and is NOT NULL; otherwise it returns its second operand.
$username = $_GET['username'] ?? 'not passed';
// Equivalent code using ternary operator
$username = isset($_GET['username']) ? $_GET['username'] : 'not passed';