--TEST-- shifting strings left --FILE-- <?php $s = "123"; $s1 = "test"; $s2 = "45345some"; $s <<= 2; var_dump($s); $s1 <<= 1; var_dump($s1); $s2 <<= 3; var_dump($s2); echo "Done\n"; ?> --EXPECTF-- int(492) Warning: A non-numeric value encountered in %s on line %d int(0) Notice: A non well formed numeric value encountered in %s on line %d int(362760) Done