<?php

    //转小写

    function lowercase($a){

        $b = str_split($a, 1);

        $r = '';

        foreach($b as $v){

            $v = ord($v);

            if($v >= 65 && $v<= 90){

                $v += 32;

            }

            $r .= chr($v);

        }

        return $r;

    }

    //转大写

    function capital($a){

        $b = str_split($a, 1);

        $r = '';

        foreach($b as $v){

            $v = ord($v);

            if($v >= 97 && $v<= 122){

                $v -= 32;

            }

            $r .= chr($v);

        }

        return $r;

    }

?>