Online PHP editor | refs for KNM3k

<?php function foo(&$str) { $str = 'xyz'; return $str; } $o = "abc"; // No errors foo($o); call_user_func('foo', $o); call_user_func('foo', [$o]); $a[] = "abc"; $a[] = "abc"; $a[] = "abc"; // Warning: Parameter 1 to foo() expected to be a reference, value given in call_user_func('foo', array_slice($a, 0, 1)); var_dump($a);