设计一个用于仿真自动售货机的仿真程序。在机器的初始状态建立后（即待售的物品、价格，以及初始的存货量），用户可以查看机器的当前状态，向机器投币，购买机器内的物品，得到物品和找零，假定自动售货机有3种待售物品。每种物品有四个属性：编号，物品名称，价格，数量。设计两个类（一个物品类Goods和一个机器类Machine）来实现这个仿真程序。（1）设计物品类Goods，实现物品类数据成员的赋值和获取；（2）设计Machine类,完成机器状态初始化（4分），显示目前物品状态（4分），购买物品（4分）三个功能。

以下是一个可能的实现，其中使用了C++语言：

#include <iostream>
#include <string>

using namespace std;

class Goods {
public:
    int id;
    string name;
    double price;
    int quantity;
    
    Goods(int id, string name, double price, int quantity) {
        this->id = id;
        this->name = name;
        this->price = price;
        this->quantity = quantity;
    }
    
    void print() {
        cout << "ID: " << id << ", Name: " << name << ", Price: " << price << ", Quantity: " << quantity << endl;
    }
};

class Machine {
public:
    Goods* goods[3];
    double balance;
    
    Machine(Goods* g1, Goods* g2, Goods* g3) {
        goods[0] = g1;
        goods[1] = g2;
        goods[2] = g3;
        balance = 0.0;
    }
    
    void printGoods() {
        cout << "Current Goods:" << endl;
        for (int i = 0; i < 3; i++) {
            goods[i]->print();
        }
    }
    
    void buy(int id) {
        if (id < 1 || id > 3) {
            cout << "Invalid input. Please try again." << endl;
            return;
        }
        Goods* g = goods[id-1];
        if (g->quantity == 0) {
            cout << "Sorry, the item is sold out." << endl;
            return;
        }
        if (balance < g->price) {
            cout << "Not enough balance. Please insert coins." << endl;
            return;
        }
        balance -= g->price;
        g->quantity--;
        cout << "You have bought " << g->name << "." << endl;
        if (balance > 0) {
            cout << "Your change is " << balance << "." << endl;
            balance = 0.0;
        }
    }
};

int main() {
    Goods* g1 = new Goods(1, "Coke", 3.0, 5);
    Goods* g2 = new Goods(2, "Pepsi", 2.5, 2);
    Goods* g3 = new Goods(3, "Water", 1.0, 10);
    Machine* m = new Machine(g1, g2, g3);
    cout << "Welcome to the vending machine simulator!" << endl;
    m->printGoods();
    while (true) {
        cout << "Please insert coins (or enter 0 to exit): ";
        double coin;
        cin >> coin;
        if (coin == 0.0) {
            break;
        }
        m->balance += coin;
        cout << "Your current balance is " << m->balance << "." << endl;
        cout << "Which item do you want to buy (1, 2, or 3)? ";
        int id;
        cin >> id;
        m->buy(id);
        m->printGoods();
    }
    cout << "Thank you for using the vending machine simulator!" << endl;
    return 0;
}

该程序中，Goods类表示待售物品，包括编号、名称、价格和数量等信息。Machine类表示自动售货机，包括当前待售物品和余额等信息，实现了初始化、显示物品状态和购买物品等功能。在主函数中，首先创建三种待售物品和一个自动售货机，然后不断循环，直到用户输入0退出程序。在每次循环中，程序会提示用户插入硬币，并显示当前余额。然后程序会要求用户选择要购买的物品，并根据用户的选择调用Machine类的buy函数进行购买。购买完成后，程序会显示当前物品状态。最后，程序会输出感谢信息并结束运行。