Online PHP editor | output for 73sJS

<?php // $_GET['myvar'] is unset echo $_GET['myvar'] ?? '' == 'hello' ? "true\n" : "false\n"; // $_GET['myvar'] is set but != 'hello' $_GET['myvar'] = 'farewell'; echo $_GET['myvar'] ?? '' == 'hello' ? "true\n" : "false\n"; // $_GET['myvar'] is set and == 'hello' $_GET['myvar'] = 'hello'; echo $_GET['myvar'] ?? '' == 'hello' ? "true\n" : "false\n"; // $_GET['myvar'] is set but "falsey" $_GET['myvar'] = 0; echo $_GET['myvar'] ?? '' == 'hello' ? "true\n" : "false\n"; $_GET['myvar'] = ''; echo $_GET['myvar'] ?? '' == 'hello' ? "true\n" : "false\n";