C语言如何实现消息推送功能

要实现消息推送功能，可以使用C语言的网络编程相关库进行开发。以下是一个简单的示例代码，使用了Linux下的socket编程：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define SERVER_PORT 8888
#define MAX_CONNECTIONS 10
#define MAX_BUFFER_SIZE 1024

// 处理客户端连接请求
void handleClient(int clientSocket) {
    char buffer[MAX_BUFFER_SIZE];
    memset(buffer, 0, sizeof(buffer));

    // 接收客户端消息
    int bytesRead = recv(clientSocket, buffer, sizeof(buffer), 0);
    if (bytesRead <= 0) {
        printf("Failed to receive message from client.\n");
        close(clientSocket);
        return;
    }

    // 打印客户端消息
    printf("Received message from client: %s\n", buffer);

    // 处理消息，这里可以根据需求进行具体的处理逻辑

    // 发送响应给客户端
    char response[] = "Message received!";
    if (send(clientSocket, response, sizeof(response), 0) <= 0) {
        printf("Failed to send response to client.\n");
    }

    close(clientSocket);
}

int main() {
    int serverSocket, clientSocket;
    struct sockaddr_in serverAddr, clientAddr;
    socklen_t clientAddrLen = sizeof(clientAddr);

    // 创建套接字
    serverSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (serverSocket == -1) {
        printf("Failed to create socket.\n");
        return -1;
    }

    // 设置地址重用
    int reuse = 1;
    if (setsockopt(serverSocket, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1) {
        printf("Failed to set socket options.\n");
        return -1;
    }

    // 绑定地址和端口
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(SERVER_PORT);
    serverAddr.sin_addr.s_addr = INADDR_ANY;
    if (bind(serverSocket, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == -1) {
        printf("Failed to bind socket.\n");
        return -1;
    }

    // 开始监听连接
    if (listen(serverSocket, MAX_CONNECTIONS) == -1) {
        printf("Failed to listen on socket.\n");
        return -1;
    }

    printf("Server started, listening on port %d.\n", SERVER_PORT);

    // 接受客户端连接请求并处理
    while (1) {
        clientSocket = accept(serverSocket, (struct sockaddr *)&clientAddr, &clientAddrLen);
        if (clientSocket == -1) {
            printf("Failed to accept client connection.\n");
            continue;
        }

        printf("Accepted client connection from %s:%d.\n", inet_ntoa(clientAddr.sin_addr), ntohs(clientAddr.sin_port));

        // 处理客户端请求
        handleClient(clientSocket);
    }

    close(serverSocket);
    return 0;
}

这个示例代码创建了一个简单的服务器，监听8888端口。当有客户端连接时，会接收客户端发送的消息，并打印出来。然后可以根据具体需求进行处理，最后发送响应给客户端。

需要注意的是，在实际的应用中，可能还需要添加一些安全性和稳定性的处理，比如使用SSL/TLS加密连接，处理多线程并发等。这只是一个简单的示例，具体实现还需要根据实际需求进行调整和完善。