金卡在现代生活里应用广泛，无论排长队于ATM机前取款还是就餐、购物、就医等等。在国外电子货币十分流行，其实电子货币是系统工程，它涉及金融、安全、通信、计算机等领域。这里为使读者掌握动态数据的用法，仅模拟其存款于取款过程。-Gold is widely used in modern life, whether long lines at the ATM machine before the withdrawal or dining, shopping, medical care and so on. Very popular in foreign electronic money, electronic money is in fact engineering, which involves financial, security, communications, computers and other fields. Here for the reader to grasp the usage of dynamic data, only simulation of its deposits in the withdrawal process.