设计一个自动售货机控制系统。该系统能完成对货物信息的存储、进程控制硬币处理、余额计算、显示等功能。可以管理4种货物，每种货物的数量和单价在初始化时输入，在存储器中存储。用户可以用硬币进行购物，按键进行货物选择，售货时能够根据用户输入的货币来判断钱币是否足足够，钱币够则根据顾客要求自动售货，钱币不够则给出提示并退出；能够自动计算出应找的钱币余额、库存数量并显示。(Design a vending machine control system. The system can complete the storage of cargo information, process control, coin handling, balance calculation, display and other functions. 4 goods can be managed. The quantity and unit price of each item is entered at initialization and stored in memory. Users can make purchases with coins, keys cargo selection, when sales can be based on user input to determine whether enough money money, enough coin vending according to customer requirements, money is not given prompt and exit; can automatically calculate the balance of money should find, inventory number and display.)