socket tcp发送接收 C代码

在C语言中，Socket编程通常用于TCP/IP网络通信，下面是一个简单的客户端和服务器的例子，展示了如何通过TCP发送和接收数据：

**服务器端（server.c）:**

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

int main() {
    int server_fd, client_sock;
    struct sockaddr_in server_addr, client_addr;
    socklen_t addr_len = sizeof(struct sockaddr_in);
    
    // 创建套接字
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket failed");
        return 1;
    }
    
    // 设置服务器地址
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT); //假设SERVER_PORT已定义
    inet_pton(AF_INET, "localhost", &server_addr.sin_addr);

    // 绑定并监听
    if (bind(server_fd, (struct sockaddr *)&server_addr, addr_len) == -1) {
        perror("bind failed");
        close(server_fd);
        return 1;
    }
    listen(server_fd, MAX_CONNECTIONS);

    // 接受连接
    if ((client_sock = accept(server_fd, (struct sockaddr *)&client_addr, &addr_len)) == -1) {
        perror("accept failed");
        close(server_fd);
        return 1;
    }

    char buffer[1024];
    printf("Server: Waiting for message...\n");

    // 读取客户端消息
    ssize_t bytes_received = recv(client_sock, buffer, sizeof(buffer), 0);
    if (bytes_received > 0) {
        buffer[bytes_received] = '\0';
        printf("Server: Received: %s\n", buffer);
        send(client_sock, "Server received your message.", strlen("Server received your message."), 0);
    } else {
        perror("recv failed");
    }

    close(client_sock);
    close(server_fd);
    return 0;
}

**客户端（client.c）:**

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

#define SERVER_IP "localhost"
#define SERVER_PORT 12345 // 假设服务器使用的端口

int main() {
    int client_sock;
    struct sockaddr_in server_addr;
    socklen_t addr_len = sizeof(struct sockaddr_in);

    // 创建套接字
    if ((client_sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
        perror("socket failed");
        return 1;
    }

    // 设置客户端地址
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    inet_pton(AF_INET, SERVER_IP, &server_addr.sin_addr);

    // 连接到服务器
    if (connect(client_sock, (struct sockaddr *)&server_addr, addr_len) == -1) {
        perror("connect failed");
        close(client_sock);
        return 1;
    }

    char input[1024];
    printf("Client: Enter a message to send: ");
    fgets(input, sizeof(input), stdin);
    input[strcspn(input, "\n")] = '\0'; // remove newline character

    // 发送消息
    if (send(client_sock, input, strlen(input), 0) == -1) {
        perror("send failed");
    }

    printf("Client: Sent: %s\n", input);

    // 接收服务器响应
    char response[1024];
    ssize_t bytes_received = recv(client_sock, response, sizeof(response), 0);
    if (bytes_received > 0) {
        response[bytes_received] = '\0';
        printf("Client: Received from Server: %s\n", response);
    } else {
        perror("recv failed");
    }

    close(client_sock);
    return 0;
}