c++手写网络服务器

要手写一个网络服务器，需要掌握以下几个方面的知识：

1. 网络编程基础：了解 TCP/IP 协议、socket 编程等基础知识。
2. 多线程编程：网络服务器需要同时处理多个客户端的请求，因此需要使用多线程技术。
3. IO 多路复用：使用 select、poll 或 epoll 等技术可以实现同时监听多个 socket 的 IO 事件，提高服务器的性能。
4. 数据结构和算法：服务器需要高效地管理连接、请求和响应等数据，因此需要掌握相关的数据结构和算法。

下面是一个简单的 C++ 网络服务器示例代码：

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <pthread.h>

const int MAX_CLIENTS = 10;
const int BUFFER_SIZE = 1024;

void* handle_client(void* arg) {
    int client_fd = *(int*)arg;
    char buffer[BUFFER_SIZE];
    while (true) {
        memset(buffer, 0, BUFFER_SIZE);
        int n = read(client_fd, buffer, BUFFER_SIZE);
        if (n <= 0) {
            break;
        }
        std::cout << "Received message: " << buffer << std::endl;
        write(client_fd, buffer, n);
    }
    close(client_fd);
    return NULL;
}

int main() {
    int server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd == -1) {
        std::cerr << "Failed to create socket" << std::endl;
        return -1;
    }

    sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(8888);

    if (bind(server_fd, (sockaddr*)&server_addr, sizeof(server_addr)) == -1) {
        std::cerr << "Failed to bind socket" << std::endl;        return -1;
    }

    if (listen(server_fd, MAX_CLIENTS) == -1) {
        std::cerr << "Failed to listen on socket" << std::endl;
        return -1;
    }

    std::cout << "Server started, listening on port 8888" << std::endl;

    while (true) {
        sockaddr_in client_addr;
        socklen_t client_len = sizeof(client_addr);
        int client_fd = accept(server_fd, (sockaddr*)&client_addr, &client_len);
        if (client_fd == -1) {
            std::cerr << "Failed to accept client connection" << std::endl;
            continue;
        }
        std::cout << "Accepted client connection from " << inet_ntoa(client_addr.sin_addr) << std::endl;

        pthread_t thread_id;
        if (pthread_create(&thread_id, NULL, handle_client, &client_fd) != 0) {
            std::cerr << "Failed to create thread for client" << std::endl;
            close(client_fd);
            continue;
        }
        pthread_detach(thread_id);
    }

    close(server_fd);
    return 0;
}