用tcp实现字符大小写转换

以下是使用TCP实现字符大小写转换的C++代码示例：

服务端代码：

#include <iostream>
#include <cstring>
#include <arpa/inet.h>
#include <unistd.h>

int main() {
    // 创建TCP Socket
    int server_socket = socket(AF_INET, SOCK_STREAM, 0);

    // 绑定IP地址和端口号
    struct sockaddr_in server_address;
    memset(&server_address, 0, sizeof(server_address));
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(8000);
    server_address.sin_addr.s_addr = htonl(INADDR_ANY);
    bind(server_socket, (struct sockaddr*)&server_address, sizeof(server_address));

    // 监听客户端连接请求
    listen(server_socket, 5);

    std::cout << "等待客户端连接..." << std::endl;

    while (true) {
        // 接收客户端连接请求
        struct sockaddr_in client_address;
        socklen_t client_address_len = sizeof(client_address);
        int client_socket = accept(server_socket, (struct sockaddr*)&client_address, &client_address_len);

        std::cout << "客户端已连接：" << inet_ntoa(client_address.sin_addr) << std::endl;

        while (true) {
            char buffer[1024] = {0};

            // 接收客户端发送的数据
            int recv_len = recv(client_socket, buffer, sizeof(buffer), 0);
            if (recv_len <= 0) {
                break;
            }

            // 将字符转换为大写或小写
            std::string str(buffer);
            if (std::all_of(str.begin(), str.end(), ::isupper)) {
                std::transform(str.begin(), str.end(), str.begin(), ::tolower);
            } else {
                std::transform(str.begin(), str.end(), str.begin(), ::toupper);
            }

            // 发送转换后的数据给客户端
            send(client_socket, str.c_str(), str.length(), 0);
        }

        // 关闭客户端连接
        close(client_socket);
    }

    // 关闭服务端Socket
    close(server_socket);

    return 0;
}

客户端代码：

#include <iostream>
#include <cstring>
#include <arpa/inet.h>
#include <unistd.h>

int main() {
    // 创建TCP Socket
    int client_socket = socket(AF_INET, SOCK_STREAM, 0);

    // 连接服务端
    struct sockaddr_in server_address;
    memset(&server_address, 0, sizeof(server_address));
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(8000);
    inet_pton(AF_INET, "127.0.0.1", &server_address.sin_addr);
    connect(client_socket, (struct sockaddr*)&server_address, sizeof(server_address));

    while (true) {
        // 获取用户输入
        std::string str;
        std::cout << "请输入字符串（输入q退出）：";
        std::getline(std::cin, str);
        if (str == "q") {
            break;
        }

        // 发送数据给服务端
        send(client_socket, str.c_str(), str.length(), 0);

        char buffer[1024] = {0};

        // 接收服务端发送的数据
        int recv_len = recv(client_socket, buffer, sizeof(buffer), 0);
        if (recv_len > 0) {
            std::string str(buffer);
            std::cout << "转换后的字符串：" << str << std::endl;
        }
    }

    // 关闭连接
    close(client_socket);

    return 0;
}

运行服务端代码和客户端代码后，可以输入字符串进行大小写转换，并且服务端会将转换后的字符串发送给客户端。