有通过C++实现的代码么

以下是使用C++实现字符大小写转换的示例代码（使用TCP套接字）：

服务端代码：

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

#define PORT 8888

int main()
{
    int server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket == -1)
    {
        std::cerr << "Failed to create socket\n";
        return -1;
    }

    sockaddr_in server_address{};
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = INADDR_ANY;
    server_address.sin_port = htons(PORT);

    if (bind(server_socket, (sockaddr*)&server_address, sizeof(server_address)) == -1)
    {
        std::cerr << "Failed to bind socket\n";
        return -1;
    }

    if (listen(server_socket, 1) == -1)
    {
        std::cerr << "Failed to listen socket\n";
        return -1;
    }

    std::cout << "Server listening on port " << PORT << "...\n";

    sockaddr_in client_address{};
    socklen_t client_address_length = sizeof(client_address);

    while (true)
    {
        int client_socket = accept(server_socket, (sockaddr*)&client_address, &client_address_length);
        if (client_socket == -1)
        {
            std::cerr << "Failed to accept connection\n";
            continue;
        }

        std::cout << "Connected by " << inet_ntoa(client_address.sin_addr) << "\n";

        while (true)
        {
            char buffer[1024]{};
            int bytes_received = recv(client_socket, buffer, sizeof(buffer), 0);
            if (bytes_received <= 0)
            {
                break;
            }

            std::string data(buffer, bytes_received);
            if (std::all_of(data.begin(), data.end(), isalpha))
            {
                std::transform(data.begin(), data.end(), data.begin(), [](unsigned char c) { return std::islower(c) ? std::toupper(c) : std::tolower(c); });
                send(client_socket, data.c_str(), data.length(), 0);
            }
        }

        close(client_socket);
    }

    close(server_socket);

    return 0;
}

客户端代码：

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

#define PORT 8888

int main()
{
    int client_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (client_socket == -1)
    {
        std::cerr << "Failed to create socket\n";
        return -1;
    }

    sockaddr_in server_address{};
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
    server_address.sin_port = htons(PORT);

    if (connect(client_socket, (sockaddr*)&server_address, sizeof(server_address)) == -1)
    {
        std::cerr << "Failed to connect to server\n";
        return -1;
    }

    while (true)
    {
        std::string data;
        std::cout << "Enter string to convert: ";
        std::getline(std::cin, data);

        if (data.empty())
        {
            break;
        }

        send(client_socket, data.c_str(), data.length(), 0);

        char buffer[1024]{};
        int bytes_received = recv(client_socket, buffer, sizeof(buffer), 0);
        if (bytes_received <= 0)
        {
            break;
        }

        std::cout << "Converted string: " << buffer << "\n";
    }

    close(client_socket);

    return 0;
}

服务端启动后，可以运行客户端并输入要转换的字符串，客户端会将其发送到服务端进行转换并输出结果。