C/C++ 编写一个服务器与客户端的群聊

以下是一个简单的基于TCP协议的服务器与客户端的群聊实现。该程序使用了多线程来支持多个客户端同时连接。

服务器代码（chat_server.c）：

#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 MAX_CLIENTS 10
#define BUFFER_SIZE 1024

int clients[MAX_CLIENTS];
int num_clients = 0;
pthread_mutex_t clients_mutex = PTHREAD_MUTEX_INITIALIZER;

void broadcast_message(char *message, int sender) {
    pthread_mutex_lock(&clients_mutex);
    for (int i = 0; i < num_clients; i++) {
        if (clients[i] != sender) {
            send(clients[i], message, strlen(message), 0);
        }
    }
    pthread_mutex_unlock(&clients_mutex);
}

void *client_thread(void *arg) {
    int client_fd = *(int*)arg;
    char buffer[BUFFER_SIZE];

    pthread_mutex_lock(&clients_mutex);
    clients[num_clients++] = client_fd;
    pthread_mutex_unlock(&clients_mutex);

    while (1) {
        int bytes_read = recv(client_fd, buffer, BUFFER_SIZE, 0);
        if (bytes_read <= 0) {
            pthread_mutex_lock(&clients_mutex);
            for (int i = 0; i < num_clients; i++) {
                if (clients[i] == client_fd) {
                    clients[i] = -1;
                    break;
                }
            }
            pthread_mutex_unlock(&clients_mutex);
            close(client_fd);
            return NULL;
        }
        buffer[bytes_read] = '\0';
        broadcast_message(buffer, client_fd);
    }
}

int main(int argc, char *argv[]) {
    int server_fd, client_fd;
    struct sockaddr_in server_addr, client_addr;
    socklen_t client_len = sizeof(client_addr);
    pthread_t tid;

    if (argc != 2) {
        printf("Usage: %s <port>\n", argv[0]);
        exit(1);
    }

    server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd < 0) {
        perror("socket");
        exit(1);
    }

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(atoi(argv[1]));

    if (bind(server_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) {
        perror("bind");
        exit(1);
    }

    if (listen(server_fd, MAX_CLIENTS) < 0) {
        perror("listen");
        exit(1);
    }

    printf("Server listening on port %s...\n", argv[1]);

    while (1) {
        client_fd = accept(server_fd, (struct sockaddr*)&client_addr, &client_len);
        if (client_fd < 0) {
            perror("accept");
            exit(1);
        }
        pthread_create(&tid, NULL, client_thread, &client_fd);
    }

    return 0;
}

客户端代码（chat_client.c）：

#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 <netdb.h>

#define BUFFER_SIZE 1024

int main(int argc, char *argv[]) {
    int client_fd, port;
    char buffer[BUFFER_SIZE];
    struct hostent *server;
    struct sockaddr_in server_addr;

    if (argc != 3) {
        printf("Usage: %s <hostname> <port>\n", argv[0]);
        exit(1);
    }

    port = atoi(argv[2]);
    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr, "Error: no such host\n");
        exit(1);
    }

    client_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (client_fd < 0) {
        perror("socket");
        exit(1);
    }

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    memcpy(&server_addr.sin_addr.s_addr, server->h_addr, server->h_length);
    server_addr.sin_port = htons(port);

    if (connect(client_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) < 0) {
        perror("connect");
        exit(1);
    }

    printf("Connected to server %s:%d\n", argv[1], port);

    while (1) {
        printf("> ");
        fgets(buffer, BUFFER_SIZE, stdin);
        send(client_fd, buffer, strlen(buffer), 0);
    }

    return 0;
}

编译方法：

gcc -o chat_server chat_server.c -lpthread
gcc -o chat_client chat_client.c

运行方法：

./chat_server <port>
./chat_client <hostname> <port>

其中，`<port>`是服务器监听的端口号，`<hostname>`是服务器的主机名或IP地址。客户端连接服务器后，可以输入任意文本并发送到服务器，服务器会将该文本广播给所有连接的客户端。