用C++实现一个数据传输

要实现数据传输，可以使用C++的网络编程库。下面是一个简单的例子，使用socket进行数据传输：

服务端代码：

#include <iostream>
#include <cstring>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>

using namespace std;

int main(int argc, char const *argv[])
{
    // 创建socket
    int server_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (server_socket == -1)
    {
        cerr << "Create socket failed!" << endl;
        return -1;
    }

    // 绑定IP和端口号
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(8888);
    if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1)
    {
        cerr << "Bind failed!" << endl;
        close(server_socket);
        return -1;
    }

    // 监听
    if (listen(server_socket, 20) == -1)
    {
        cerr << "Listen failed!" << endl;
        close(server_socket);
        return -1;
    }

    cout << "Server is listening..." << endl;

    // 接收连接请求
    struct sockaddr_in client_addr;
    socklen_t client_addr_len = sizeof(client_addr);
    int client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addr_len);
    if (client_socket == -1)
    {
        cerr << "Accept failed!" << endl;
        close(server_socket);
        return -1;
    }

    cout << "Connection established!" << endl;

    // 发送数据
    char message[] = "Hello, client!";
    if (send(client_socket, message, strlen(message), 0) == -1)
    {
        cerr << "Send failed!" << endl;
        close(client_socket);
        close(server_socket);
        return -1;
    }

    // 关闭连接
    close(client_socket);
    close(server_socket);

    return 0;
}

客户端代码：

#include <iostream>
#include <cstring>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>

using namespace std;

int main(int argc, char const *argv[])
{
    // 创建socket
    int client_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (client_socket == -1)
    {
        cerr << "Create socket failed!" << endl;
        return -1;
    }

    // 连接服务器
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_addr.sin_port = htons(8888);
    if (connect(client_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1)
    {
        cerr << "Connect failed!" << endl;
        close(client_socket);
        return -1;
    }

    // 接收数据
    char buffer[1024] = {0};
    if (recv(client_socket, buffer, sizeof(buffer), 0) == -1)
    {
        cerr << "Receive failed!" << endl;
        close(client_socket);
        return -1;
    }

    cout << "Server says: " << buffer << endl;

    // 关闭连接
    close(client_socket);

    return 0;
}

在这个例子中，服务端创建了一个socket，并绑定了IP和端口号，然后开始监听客户端连接请求。客户端创建了一个socket，并连接到服务端指定的IP和端口号。连接成功后，客户端向服务端发送数据，服务端接收到数据后，向客户端回复数据。最后客户端和服务端关闭连接。

这只是一个简单的例子，实际应用中需要考虑更多的问题，如数据包的大小，传输速度，错误处理等。