php生成随机字符串

function randHash() {
    $code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $rand = $code[rand(0, 25) ] . strtoupper(dechex(date('m'))) . date('d') . substr(time() , -5) . substr(microtime() , 2, 5) . sprintf('%02d', rand(0, 99));
    for ($a = md5($rand, true) , $s = '0123456789ABCDEFGHIJKLMNOPQRSTUV', $d = '', $f = 0; $f < 8; $g = ord($a[$f]) , $d.= $s[($g ^ ord($a[$f + 8])) - $g & 0x1F], $f++);
    return $d;
}
?>