设计要点：

　　使用文本命令行界面。当输入给定的卡号和密码（初始卡号和密码为123456）时，系统能登录ATM柜员机系统，用户可以按照以下规则进行：

查询余额：初始余额为10000元

ATM取款：每次取款金额为100的倍数，总额不超过5000元，支取金额不允许透支。

ATM存款：不能出现负存款。

修改密码：新密码长度不小于6位，不允许出现6位完全相同的情况，只有旧密码正确，新密码符合要求，且两次输入相同的情况下才可以成功修改密码。-Design features: use a text command line interface. When given input card number and password (the initial card number and password is 123456), the system can log the ATM to the system, users can be carried out in accordance with the following rules: balance inquiries: initial balance of 10,000 yuan ATM withdrawals: each withdrawal amount to a multiple of 100, the total is not more than 5000 yuan, the withdrawal amount does not allow overdrafts. The ATM deposits: can not be negative deposits. Modify password: New password length is not less than 6, 6 are not allowed in the exact same situation, only the old password is correct, meet the requirements of the new password twice, and enter the same case can successfully modify password.