php 生成唯一的随机字符串

Posted 2021-05-04

function randomString($length = 13) 
{
    // uniqid gives 13 chars, but you could adjust it to your needs.
    if (function_exists("random_bytes")) {
        $bytes = random_bytes(ceil($length / 2));
    } elseif (function_exists("openssl_random_pseudo_bytes")) {
        $bytes = openssl_random_pseudo_bytes(ceil($length / 2));
    } else {
        throw new Exception("no cryptographically secure random function available");
    }
    return substr(bin2hex($bytes), 0, $length);
}