生成随机字符串，包含大写、小写字母、数字php代码

<script>ec(2);</script>

function randstr($length) {
 $hash = '';
 $chars = 'abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz';
 $max = strlen($chars) - 1;
 mt_srand((double)microtime() * 1000000);
 for($i = 0; $i   $hash .= $chars[mt_rand(0, $max)];
 }
 return $hash;
}