--TEST-- preg_replace_callback() 2 --FILE-- 'aksfjk', 12 => 'aa bb'))); var_dump(preg_replace_callback('~\A.~', 'g', array(array('xyz')))); var_dump(preg_replace_callback('~\A.~', function($m) { return strtolower($m[0]); }, 'ABC')); ?> --EXPECTF-- array(3) { [0]=> string(12) "'a' 'b3' bcd" ["v"]=> string(6) "aksfjk" [12]=> string(9) "'aa' 'bb'" } Notice: Array to string conversion in %spreg_replace_callback2.php on line 17 array(1) { [0]=> string(7) "'A'rray" } string(3) "aBC"