C++ 实现一套按需订阅向互联网订阅

实现按需订阅向互联网订阅需要使用网络编程技术，可以用C++的socket库实现。以下是一个简单的示例代码：

#include <iostream>
#include <string>
#include <vector>
#include <winsock2.h> //windows下的socket库头文件

#pragma comment(lib,"ws2_32.lib") //windows下需要链接的库文件

using namespace std;

//定义产品类
class Product{
public:
    Product(string name, double price){
        m_name = name;
        m_price = price;
    }
    string getName(){
        return m_name;
    }
    double getPrice(){
        return m_price;
    }
private:
    string m_name;
    double m_price;
};

//定义订阅类
class Subscription{
public:
    Subscription(){
        m_totalPrice = 0;
    }
    void addProduct(Product product){
        m_products.push_back(product);
        m_totalPrice += product.getPrice();
    }
    void removeProduct(string name){
        for(int i=0; i<m_products.size(); i++){
            if(m_products[i].getName() == name){
                m_totalPrice -= m_products[i].getPrice();
                m_products.erase(m_products.begin() + i);
                break;
            }
        }
    }
    double getTotalPrice(){
        return m_totalPrice;
    }
private:
    vector<Product> m_products;
    double m_totalPrice;
};

//发送消息到服务器
void sendMessage(SOCKET clientSocket, string msg){
    send(clientSocket, msg.c_str(), msg.length(), 0);
}

//从服务器接收消息
string receiveMessage(SOCKET clientSocket){
    char buffer[1024];
    int len = recv(clientSocket, buffer, 1024, 0);
    buffer[len] = '\0';
    return string(buffer);
}

//测试代码
int main(){
    //初始化socket库
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);

    //创建socket
    SOCKET clientSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    //连接服务器
    sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); //服务器IP地址
    serverAddr.sin_port = htons(12345); //服务器端口号
    connect(clientSocket, (sockaddr*)&serverAddr, sizeof(serverAddr));

    //定义产品
    Product product1("产品1", 10.0);
    Product product2("产品2", 20.0);
    Product product3("产品3", 30.0);

    //定义订阅
    Subscription sub;

    //添加产品
    sub.addProduct(product1);
    sub.addProduct(product2);
    sub.addProduct(product3);

    //发送订阅信息到服务器
    string msg = "subscribe:" + to_string(sub.getTotalPrice());
    sendMessage(clientSocket, msg);

    //接收服务器的确认信息
    string response = receiveMessage(clientSocket);
    cout << response << endl;

    //移除产品
    sub.removeProduct("产品2");

    //发送更新订阅信息到服务器
    msg = "update:" + to_string(sub.getTotalPrice());
    sendMessage(clientSocket, msg);

    //接收服务器的确认信息
    response = receiveMessage(clientSocket);
    cout << response << endl;

    //关闭socket
    closesocket(clientSocket);

    //清理socket库
    WSACleanup();

    return 0;
}

上述代码演示了如何使用socket库实现向互联网订阅并更新订阅的功能。在实际应用中，还需要实现服务器端的订阅管理、支付处理和安全认证等功能。