PHP获取随机字符串

/**
 * 获取随机字符串
 * @param int $randLength  长度
 * @param int $addtime  是否加入当前时间戳
 * @param int $includenumber   是否包含数字
 * @return string
 */
function get_rand_str($randLength = 6, $addtime = 1, $includenumber = 0) {
    if ($includenumber) {
        $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHJKLMNPQEST123456789';
    } else {
        $chars = 'abcdefghijklmnopqrstuvwxyz';
    }
    $len = strlen($chars);
    $randStr = '';
    for ($i = 0; $i < $randLength; $i++) {
        $randStr.=$chars[rand(0, $len - 1)];
    }
    $tokenvalue = $randStr;
    if ($addtime) {
        $tokenvalue = $randStr . time();
    }
    return $tokenvalue;
}