Online PHP editor | output for A58l0

<?php // $_GET['myvar'] isn't set... echo ($_GET['myvar'] ?? '') == 'hello' ? "hello!\n" : "goodbye!\n"; // $_GET['myvar'] is set but != 'hello' $_GET['myvar'] = 'farewell'; echo ($_GET['myvar'] ?? '') == 'hello' ? "hello!\n" : "goodbye!\n"; // $_GET['myvar'] is set and == 'hello' $_GET['myvar'] = 'hello'; echo ($_GET['myvar'] ?? '') == 'hello' ? "hello!\n" : "goodbye!\n";