Re: reverse string without strrev();

On Thu, 2008-02-28 at 16:26 +0000, Robin Vickery wrote: > On 28/02/2008, Robert Cummings <robert@interjinn.com> wrote: > > > > There's always a tradeoff between speed and memory. Here's the low > > memory version: > > > > <?php > > > > $str = '1234567'; > > str_reverse_in_place( $str ); > > echo 'Reversed: '.$str."\n"; > > > > function str_reverse_in_place( &$str ) > > { > > $a = 0; > > $z = strlen( $str ) - 1; > > > > while( $a < $z ) > > { > > $t = $str[$a]; > > $str[$a] = $str[$z]; > > $str[$z] = $t; > > > > ++$a; > > --$z; > > } > > } > > > > ?> > > > every byte counts :-) > > function str_reverse_in_place( &$str ) > { > $a = -1; > $z = strlen($str); > > while( ++$a < --$z ) > { > $str[$a] = $str[$a] ^ $str[$z]; > $str[$z] = $str[$a] ^ $str[$z]; > $str[$a] = $str[$a] ^ $str[$z]; > } > } > Nicely done. Cheers, Rob. -- .------------------------------------------------------------. | InterJinn Application Framework - http://www.interjinn.com | :------------------------------------------------------------: | An application and templating framework for PHP. Boasting | | a powerful, scalable system for accessing system services | | such as forms, properties, sessions, and caches. InterJinn | | also provides an extremely flexible architecture for | | creating re-usable components quickly and easily. | `------------------------------------------------------------'