//随机生成邀请码 function getRandomString($len, $chars=null) { if (is_null($chars)){ $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; } for ($i = 0, $str = '', $lc = strlen($chars)-1; $i < $len; $i++){ $str .= $chars[mt_rand(0, $lc)]; } return $str; } getRandomString(6); //生成6位随机邀请码