<html> <body> <div> <?php function tagWrap( $tag, $txt, $func="" ) { if ( function_exists( $func ) ) $txt = $func( $txt ); return "<$tag>$txt</$tag>\n"; } function subscript( $txt ) { return "<sub>$txt</sub>"; } print tagWrap('b', 'bold'); print tagWrap('i', 'i', "subscript"); ?> </div> </body> </html>