Php产生随机字符串函数

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<?php
/**
* 产生随机字符串
*
* 产生一个指定长度的随机字符串,并返回给用户
*
* *access public
* *param int $len 产生字符串的位数
* *return string
*/
function randStr($len=6) {
$chars='ABDEFGHJKLMNPQRSTVWXYabdefghijkmnpqrstvwxy23456789#%*'; // characters to build the password from
mt_srand((double)microtime()*1000000*getmypid()); // seed the random number generater (must be done)
$password='';
while(strlen($password)<$len)
$password.=substr($chars,(mt_rand()%strlen($chars)),1);
return $password;
}
?>