C# 饮料类继承和多态实现：茶、咖啡和牛奶的收费系统

运用C#语言，写出代码内容：using System;

namespace ConsoleApp1 { class Drink { protected int id; protected int num; protected double price;

    public Drink(int id, int num, double price)
    {
        this.id = id;
        this.num = num;
        this.price = price;
    }

    public virtual void print()
    {
        Console.WriteLine(id + ' ' + Math.Round(num * price, 1));
    }
}

class Tea : Drink
{
    private int areaCode;
    const double serviceCharge1 = 0.5;
    const double serviceCharge2 = 0.2;

    public Tea(int id, int num, double price, int areaCode) : base(id, num, price)
    {
        this.areaCode = areaCode;
    }

    public override void print()
    {
        double charge = 0;
        if (areaCode == 1)
        {
            charge = num * price * serviceCharge1;
        }
        else
        {
            charge = num * price * serviceCharge2;
        }
        Console.WriteLine(id + ' ' + Math.Round(num * price + charge, 1));
    }
}

class Coffee : Drink
{
    private int processCode;
    const double serviceCharge1 = 1.0;
    const double serviceCharge2 = 0.2;

    public Coffee(int id, int num, double price, int processCode) : base(id, num, price)
    {
        this.processCode = processCode;
    }

    public override void print()
    {
        double charge = 0;
        if (processCode == 1)
        {
            charge = num * price * serviceCharge1;
        }
        else
        {
            charge = num * price * serviceCharge2;
        }
        Console.WriteLine(id + ' ' + Math.Round(num * price + charge, 1));
    }
}

class Milk : Drink
{
    public Milk(int id, int num, double price) : base(id, num, price)
    {
    }
}

class Program
{
    static void Main(string[] args)
    {
        Drink[] drinks = new Drink[10];
        int count = 0;
        string line;
        while ((line = Console.ReadLine()) != "0")
        {
            string[] items = line.Split(' ');
            int type = int.Parse(items[0]);
            int id = int.Parse(items[1]);
            int num = int.Parse(items[2]);
            double price = double.Parse(items[3]);
            switch (type)
            {
                case 1:
                    int areaCode = int.Parse(items[4]);
                    if (areaCode != 1 && areaCode != 2)
                    {
                        Console.WriteLine("Drink type error.");
                    }
                    else if (id < 100 || id > 999)
                    {
                        Console.WriteLine("Drink ID error.");
                    }
                    else if (num < 0)
                    {
                        Console.WriteLine("Drink number error.");
                    }
                    else if (price < 0)
                    {
                        Console.WriteLine("Drink price error.");
                    }
                    else
                    {
                        drinks[count] = new Tea(id, num, price, areaCode);
                        count++;
                    }
                    break;
                case 2:
                    int processCode = int.Parse(items[4]);
                    if (processCode != 1 && processCode != 2)
                    {
                        Console.WriteLine("Drink type error.");
                    }
                    else if (id < 100 || id > 999)
                    {
                        Console.WriteLine("Drink ID error.");
                    }
                    else if (num < 0)
                    {
                        Console.WriteLine("Drink number error.");
                    }
                    else if (price < 0)
                    {
                        Console.WriteLine("Drink price error.");
                    }
                    else
                    {
                        drinks[count] = new Coffee(id, num, price, processCode);
                        count++;
                    }
                    break;
                case 3:
                    if (id < 100 || id > 999)
                    {
                        Console.WriteLine("Drink ID error.");
                    }
                    else if (num < 0)
                    {
                        Console.WriteLine("Drink number error.");
                    }
                    else if (price < 0)
                    {
                        Console.WriteLine("Drink price error.");
                    }
                    else
                    {
                        drinks[count] = new Milk(id, num, price);
                        count++;
                    }
                    break;
                default:
                    Console.WriteLine("Drink type error.");
                    break;
            }
        }
        for (int i = 0; i < count; i++)
        {
            drinks[i].print();
        }
    }
}

}