设计了一个模仿POS收银的程序，把食品按照 编号/名字/价格 的方式存放在预先写好的一个文件里（文本文件或者二进制文件）。给客户买单的时候，输入购买物品的 编号和数量 ，系统自动计算价格和累计价格。最后打印出总价格。付款的时候，营业员输入总付款金额，系统打印找零的数值。

（1）　　此外，系统需要显示总的营业额并保存到每日的文件中。

（2）　　每个用户的买单的明细，写入到明细文件中。并且要有每单的合计金额。

（3）　　输出各种食品当日分别的卖出数量和收费小计

-Design a imitate POS cashier s procedure, the food according to Numbers/name/price way in advance written in a file (text files or binary file). To the customer when the bill, input purchases Numbers and quantity, the system automatically calculate the price and total price. The last to print out the total price. Payment, assistant total payment amount input, the system of the numerical value of print for change.

(1) in addition, the system needs to show total turnover and save to daily file.

(2) pay for every user of the details, written to detail file. And should have every single the aggregate amount.

(3) output various food sold on the quantity and the charges were small gauge