2、运算符重载（60分） class Product { string name; //产品名称 int price; //产品单价 int quantity； //剩余产品数量 public: Product(string n,int p int q); Product operator = (const Product &p); friend bool operator >(const Product &p1, const Product &p2); friend ostream& operator<<(ostream &out, Product &t ); }; 类Product说明如上所示，完成四个函数的定义，并在main函数中进行测试。

以下是类 `Product` 的完整定义及四个函数的实现：

#include <iostream>
#include <string>

using namespace std;

class Product {
    string name;      // 产品名称
    int price;        // 产品单价
    int quantity;     // 剩余产品数量

public:
    Product(string n, int p, int q);
    Product operator=(const Product& p);
    friend bool operator>(const Product& p1, const Product& p2);
    friend ostream& operator<<(ostream& out, Product& t);
};

Product::Product(string n, int p, int q) {
    name = n;
    price = p;
    quantity = q;
}

Product Product::operator=(const Product& p) {
    name = p.name;
    price = p.price;
    quantity = p.quantity;
    return *this;
}

bool operator>(const Product& p1, const Product& p2) {
    if (p1.price > p2.price) {
        return true;
    } else {
        return false;
    }
}

ostream& operator<<(ostream& out, Product& t) {
    out << "Product Name: " << t.name << endl;
    out << "Price: " << t.price << endl;
    out << "Quantity: " << t.quantity << endl;
    return out;
}

int main() {
    Product p1("Product1", 10, 50);
    Product p2("Product2", 20, 30);

    cout << "p1: " << endl;
    cout << p1 << endl;

    cout << "p2: " << endl;
    cout << p2 << endl;

    if (p1 > p2) {
        cout << "p1 is more expensive than p2." << endl;
    } else {
        cout << "p2 is more expensive than p1." << endl;
    }

    p2 = p1;
    cout << "p2 after assignment: " << endl;
    cout << p2 << endl;

    return 0;
}

输出结果为：

p1:
Product Name: Product1
Price: 10
Quantity: 50

p2:
Product Name: Product2
Price: 20
Quantity: 30

p2 is more expensive than p1.
p2 after assignment:
Product Name: Product1
Price: 10
Quantity: 50

其中，运算符重载函数 `operator>` 用于比较两个产品的单价大小，运算符重载函数 `operator<<` 用于输出产品的信息，运算符重载函数 `operator=` 用于实现产品对象之间的赋值操作。在主函数中，我们创建了两个产品对象 `p1` 和 `p2`，并对它们进行了比较和赋值操作。