PHP随机生成n位字符串

//随机生成n位字符串

function rand_str($num){

$str = "qwertyuioplkjhgfdsazxcvbnmQAZWSXEDCRFVTGBYHNUJMIKOLP1234567890";

$str_len = strlen($str)-1;

//echo $str_len;

$s='';

for ($i = 0; $i < $num; $i++) {

$s.=$str[rand(0, $str_len)];

}

echo $s;

}

rand_str(32);

?>