用户名自动生成随机数

 $str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
 $suoyin = rand(0, 52);
 $ygid = "TYHY_".substr($str,$suoyin, 1).rand(0, 9).rand(0, 9).rand(0, 9).rand(0, 9);