PHP生成随机字符串与唯一字符串

<?php/* * 生成随机字符串 * @param int $length 生成随机字符串的长度 * @param string $char 组成随机字符串的字符串 * @return string $string 生成的随机字符串 */function str_rand($length = 32, $char = ‘0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ‘) { ???if(!is_int($length) || $length < 0) { ???????return false; ???} ???$string = ‘‘; ???for($i = $length; $i > 0; $i--) { ???????$string .= $char[mt_rand(0, strlen($char) - 1)]; ???} ???return $string;}echo str_rand(),"<br />";/* * 生成32位唯一字符串 */$uniqid = md5(uniqid(microtime(true),true));echo $uniqid;