PHP/Functions/call user func

mixed call_user_func ( function callback [, mixed param1 [, mixed ...]] ) calls an existing PHP function

   <source lang="html4strict">

<?

   $func = "str_replace";
   $output_single = call_user_func($func, "monkeys", "giraffes", "Hundreds and
   thousands of monkeys\n");

?>

 </source>