C#“委托”和“事件”模拟信用卡还款

前言

• “委托”，“事件”是C#编程语言的高级特性之一。
  • “委托”类似于C语言中的函数指针，使相同类型，相同形参的函数能被灵活的切换和使用。
  • 其实“事件”的类型就是“委托”，被称为回调方法。
• gitee网址：https://gitee.com/kittysmith5/csharp-learning-record/blob/master/cs-code/creditcard/ConsoleApp/Program.cs

核心代码

　　委托和事件声明类

class CreditCardDelegete
    {
        public delegate void card(User uesr);
        public event card DeMoney;//定期扣款事件绑定委托

        //判断事件是否启用
        public void DeMoneyTest(User user)
        {
            if (DeMoney != null)
            {
                DeMoney(user);
            }
            else
            {
                Console.WriteLine("还款日未到");
            }
        }
    }

　　用户字段类

 class User
    {
        private int balance;
        private int debt;
        private string name;
        private int day;
        public User(int balance, int debt, string name, int date)
        {
            this.balance = balance;
            this.debt = debt;
            this.name = name;
            this.day = date;
        }
        //属性，用匿名函数赋值、取值
        public int Balance { get => balance; set => balance = value; }
        public string Name { get => name; set => name = value; }
        public int Debt { get => debt; set => debt = value; }
        public int Date { get => day; set => day = value; }
    }

　　银行还款系统类

class Bank
    {
        public void DeMoneying(User user)
        {
            Console.WriteLine("{0},您的信用卡余额为{1}元，本次还款{2}元，信用卡目前余额为{3}元！",
                 user.Name, user.Balance, user.Debt, (user.Balance - user.Debt));
            Console.WriteLine();
        }
    }

　　main方法入口

static void Main(string[] agrs)
        {
            CreditCardDelegete d1 = new CreditCardDelegete();
           
            User user = new User(521, 520, "马化腾", 8000);
            Bank bank = new Bank();

            d1.DeMoney += bank.DeMoneying;//银行扣款函数订阅扣款事件


            for (int i = 0; i <= 10000; i++)
            {
                if (i == user.Date)
                    d1.DeMoneyTest(user);
            }
        }

输出结果