用c语言写多线程实现网络聊天程序

好的，以下是一个简单的使用 C 语言多线程实现网络聊天程序的示例代码，代码注释中有详细的说明：

服务器端代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <pthread.h>

#define PORT 8888
#define MAX_CLIENTS 5
#define MAX_MESSAGE_SIZE 1024

// 客户端信息结构体
struct client_info {
    int sock_fd; // 客户端 socket 文件描述符
    struct sockaddr_in addr; // 客户端地址信息
};

// 消息队列
struct message_queue {
    char message[MAX_MESSAGE_SIZE];
    int sender_sock_fd;
};

int client_count = 0; // 当前连接的客户端数量
struct client_info clients[MAX_CLIENTS]; // 客户端数组
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; // 互斥锁
struct message_queue message_queue[MAX_CLIENTS * 10]; // 消息队列
int message_count = 0; // 消息队列中的消息数量

// 将消息加入到消息队列中
void add_message_to_queue(char *message, int sender_sock_fd) {
    pthread_mutex_lock(&mutex);
    if (message_count < MAX_CLIENTS * 10) {
        struct message_queue msg;
        strncpy(msg.message, message, MAX_MESSAGE_SIZE);
        msg.sender_sock_fd = sender_sock_fd;
        message_queue[message_count++] = msg;
    }
    pthread_mutex_unlock(&mutex);
}

// 将消息从消息队列中取出并发送给所有其他客户端
void broadcast_message() {
    pthread_mutex_lock(&mutex);
    while (message_count > 0) {
        struct message_queue msg = message_queue[--message_count];
        for (int i = 0; i < client_count; i++) {
            if (clients[i].sock_fd != msg.sender_sock_fd) {
                send(clients[i].sock_fd, msg.message, strlen(msg.message), 0);
            }
        }
    }
    pthread_mutex_unlock(&mutex);
}

// 与客户端进行通信的工作线程函数
void *client_handler(void *arg) {
    int sock_fd = *(int *)arg;
    char buffer[MAX_MESSAGE_SIZE];
    int nbytes;

    // 接收客户端发送的消息并转发给其他客户端
    while ((nbytes = recv(sock_fd, buffer, MAX_MESSAGE_SIZE, 0)) > 0) {
        buffer[nbytes] = '\0';
        add_message_to_queue(buffer, sock_fd);
        broadcast_message();
    }

    // 客户端断开连接
    pthread_mutex_lock(&mutex);
    for (int i = 0; i < client_count; i++) {
        if (clients[i].sock_fd == sock_fd) {
            printf("Client %s:%d disconnected\n", inet_ntoa(clients[i].addr.sin_addr), ntohs(clients[i].addr.sin_port));
            for (int j = i; j < client_count - 1; j++) {
                clients[j] = clients[j + 1];
            }
            client_count--;
            break;
        }
    }
    pthread_mutex_unlock(&mutex);

    close(sock_fd);
    pthread_exit(NULL);
}

int main() {
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr;
    pthread_t threads[MAX_CLIENTS];
    
    // 创建服务器 socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }

    // 设置服务器地址信息
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = INADDR_ANY;
    memset(&(server_addr.sin_zero), '\0', 8);

    // 绑定服务器 socket 和地址信息
    if (bind(server_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) {
        perror("bind");
        exit(1);
    }

    // 开始监听端口
    if (listen(server_fd, MAX_CLIENTS) == -1) {
        perror("listen");
        exit(1);
    }

    printf("Server started on port %d\n", PORT);

    // 接受客户端连接并创建工作线程
    while (1) {
        socklen_t sin_size = sizeof(struct sockaddr_in);
        if ((client_fd = accept(server_fd, (struct sockaddr *)&client_addr, &sin_size)) == -1) {
            perror("accept");
            continue;
        }

        // 如果客户端数量已经达到上限，则拒绝连接
        if (client_count >= MAX_CLIENTS) {
            printf("Client %s:%d rejected\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
            close(client_fd);
            continue;
        }

        // 添加客户端信息到数组中，并创建工作线程
        clients[client_count].sock_fd = client_fd;
        clients[client_count].addr = client_addr;
        printf("Client %s:%d connected\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
        pthread_create(&threads[client_count], NULL, client_handler, &clients[client_count].sock_fd);
        client_count++;
    }

    close(server_fd);
    return 0;
}

客户端代码：

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

#define SERVER_ADDR "127.0.0.1"
#define PORT 8888
#define MAX_MESSAGE_SIZE 1024

int main() {
    int sock_fd;
    struct sockaddr_in server_addr;
    char message[MAX_MESSAGE_SIZE];

    // 创建客户端 socket
    if ((sock_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket");
        exit(1);
    }

    // 设置服务器地址信息
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = inet_addr(SERVER_ADDR);
    memset(&(server_addr.sin_zero), '\0', 8);

    // 连接服务器
    if (connect(sock_fd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) {
        perror("connect");
        exit(1);
    }

    printf("Connected to server %s:%d\n", SERVER_ADDR, PORT);

    // 发送消息给服务器
    while (1) {
        printf("Enter message: ");
        fgets(message, MAX_MESSAGE_SIZE, stdin);
        send(sock_fd, message, strlen(message) - 1, 0);
    }

    close(sock_fd);
    return 0;
}

请注意，这仅是一个简单的示例代码，可以作为实现多线程网络聊天程序的参考。在实际应用中，还需要考虑更多的细节问题，如线程安全、内存管理、异常处理等。