2021-04-30 VSC++：EAN13条形码校验。

void EAN13条形码校验()
{//缘由https://bbs.csdn.net/topics/399170504 6901234567892 6912345678902 6923456789999 6901028075763
	string t = ""; int a = 0, q = 0;
	std::cin >> t;
	while (++a < 13)
		q += (t[a - 1] - '0') * ((a % 2) ? 1 : 3);
	if ((((10 - q % 10) % 10) == (t[12] - '0')))
	{
		a = 2; std::cout << "厂";
		while (++a < 12)
			std::cout << t[a] << ((t[2] != '2' && a == 6) || (t[2] == '2' && a == 7) ? "商" : "");
		std::cout << "验" << t[12] << endl;
	}
}