需求:抢码功能
要求:
1、特定时间段才开放抢码;
2、每个时间段放开的码是有限的;
3、每个码不允许重复;
实现:
1、在不考虑并发的情况下实现:
function get_code($len){
$CHAR_ARR = array('1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','X','Y','Z','W','S','R','T');
$CHAR_ARR_LEN = count($CHAR_ARR) - 1;
$co