基于Linux的C或C++代码实现

好的，以下是基于Linux的C语言代码实现：

服务端代码：

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

#define PORT 8000

void handle_request(int client_socket) {
    char buf[1024];
    int len = recv(client_socket, buf, sizeof(buf), 0);
    if (len == -1) {
        perror("recv");
        return;
    }
    buf[len] = '\0';
    if (strcmp(buf, "liu") == 0) {
        send(client_socket, "Hello, You are connected!", 26, 0);
    } else {
        send(client_socket, "Sorry, you are not the user!", 29, 0);
    }
    printf("Received from client: %s\n", buf);
    close(client_socket);
}

int main() {
    int server_socket, client_socket;
    struct sockaddr_in server_addr, client_addr;
    int client_len = sizeof(client_addr);

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

    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(PORT);

    if (bind(server_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("bind");
        exit(1);
    }

    if (listen(server_socket, 1) == -1) {
        perror("listen");
        exit(1);
    }

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

    while (1) {
        client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_len);
        if (client_socket == -1) {
            perror("accept");
            continue;
        }
        printf("Connected from %s:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
        handle_request(client_socket);
    }

    close(server_socket);
    return 0;
}

客户端代码：

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

#define PORT 8000

int main() {
    int client_socket;
    struct sockaddr_in server_addr;

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

    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_addr.sin_port = htons(PORT);

    if (connect(client_socket, (struct sockaddr *)&server_addr, sizeof(server_addr)) == -1) {
        perror("connect");
        exit(1);
    }

    char user[1024];
    printf("Enter your username: ");
    scanf("%s", user);

    if (send(client_socket, user, strlen(user), 0) == -1) {
        perror("send");
        exit(1);
    }

    char buf[1024];
    int len = recv(client_socket, buf, sizeof(buf), 0);
    if (len == -1) {
        perror("recv");
        exit(1);
    }
    buf[len] = '\0';
    printf("%s\n", buf);

    close(client_socket);
    return 0;
}

使用方法：

1. 打开终端，进入服务端代码所在目录，输入命令：`gcc server.c -o server`，编译服务端程序，生成可执行文件；
2. 再输入命令：`./server`，启动服务端程序，服务端就会在本地8000端口监听客户端连接；
3. 打开另一个终端，进入客户端代码所在目录，输入命令：`gcc client.c -o client`，编译客户端程序，生成可执行文件；
4. 再输入命令：`./client`，客户端会要求输入用户名，输入后按回车键发送给服务端；
5. 服务端接收到客户端发送的用户名后，判断是否为“liu”，根据判断结果发送不同的字符串给客户端；
6. 客户端接收到服务端发送的字符串后，打印输出，并关闭连接。