work task

client.cpp

#define WIN32_LEAN_AND_MEAN

#include <iostream>
#include <string>
#include <windows.h>
#include <ws2tcpip.h>
using namespace std;

#pragma comment (lib, "Ws2_32.lib")

#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"
#define PAUSE 1000

int main() {
    setlocale(0, "");
    system("title CLIENT SIDE");
    cout << "Client process started!\n";
    Sleep(PAUSE);

    WSADATA wsaData;
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        cout << "WSAStartup failed with error: " << iResult << "\n";
        return 11;
    }

    addrinfo hints{};
    ZeroMemory(&hints, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;

    const char* ip = "localhost";
    addrinfo* result = NULL;
    iResult = getaddrinfo(ip, DEFAULT_PORT, &hints, &result);
    if (iResult != 0) {
        cout << "getaddrinfo failed with error: " << iResult << "\n";
        WSACleanup();
        return 12;
    }

    SOCKET ConnectSocket = INVALID_SOCKET;
    for (addrinfo* ptr = result; ptr != NULL; ptr = ptr->ai_next) {
        ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype, ptr->ai_protocol);
        if (ConnectSocket == INVALID_SOCKET) {
            cout << "socket failed with error: " << WSAGetLastError() << "\n";
            WSACleanup();
            return 13;
        }

        iResult = connect(ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
        if (iResult == SOCKET_ERROR) {
            closesocket(ConnectSocket);
            ConnectSocket = INVALID_SOCKET;
            continue;
        }
        break;
    }
    freeaddrinfo(result);

    if (ConnectSocket == INVALID_SOCKET) {
        cout << "Unable to connect to server. Please check if the server process is running!\n";
        WSACleanup();
        return 14;
    }

    cout << "Connection to server succeeded!\n";
    Sleep(PAUSE);

    char answer[DEFAULT_BUFLEN];
    string userInput;

    while (true) {
        cout << "Введіть ціле число (або 'exit' для виходу): ";
        getline(cin, userInput);

        if (userInput == "exit") {
            cout << "Завершення роботи клієнта.\n";
            break;
        }

        // Отправка числа
        iResult = send(ConnectSocket, userInput.c_str(), (int)userInput.size(), 0);
        if (iResult == SOCKET_ERROR) {
            cout << "send failed with error: " << WSAGetLastError() << "\n";
            break;
        }

        // Получение ответа
        iResult = recv(ConnectSocket, answer, DEFAULT_BUFLEN - 1, 0);
        if (iResult > 0) {
            answer[iResult] = '\0';
            cout << "Відповідь сервера (число+1): " << answer << "\n";
        }
        else if (iResult == 0) {
            cout << "Connection closed by server.\n";
            break;
        }
        else {
            cout << "recv failed with error: " << WSAGetLastError() << "\n";
            break;
        }
    }

    closesocket(ConnectSocket);
    WSACleanup();
    cout << "Client process is shutting down!\n";
    return 0;
}

server.cpp

#define WIN32_LEAN_AND_MEAN

#include <iostream>
#include <string>
#include <ws2tcpip.h>
#include <windows.h>
using namespace std;

#pragma comment (lib, "Ws2_32.lib")

#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"
#define PAUSE 1000

int main() {
    setlocale(0, "");
    system("title SERVER SIDE");
    cout << "Server process started!\n";
    Sleep(PAUSE);

    WSADATA wsaData;
    int iResult = WSAStartup(MAKEWORD(2, 2), &wsaData);
    if (iResult != 0) {
        cout << "WSAStartup failed with error: " << iResult << "\n";
        return 1;
    }

    addrinfo hints{};
    hints.ai_family = AF_INET;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    hints.ai_flags = AI_PASSIVE;

    addrinfo* result = NULL;
    iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
    if (iResult != 0) {
        cout << "getaddrinfo failed with error: " << iResult << "\n";
        WSACleanup();
        return 2;
    }

    SOCKET ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
    if (ListenSocket == INVALID_SOCKET) {
        cout << "socket failed with error: " << WSAGetLastError() << "\n";
        freeaddrinfo(result);
        WSACleanup();
        return 3;
    }

    iResult = bind(ListenSocket, result->ai_addr, (int)result->ai_addrlen);
    if (iResult == SOCKET_ERROR) {
        cout << "bind failed with error: " << WSAGetLastError() << "\n";
        freeaddrinfo(result);
        closesocket(ListenSocket);
        WSACleanup();
        return 4;
    }

    freeaddrinfo(result);

    iResult = listen(ListenSocket, SOMAXCONN);
    if (iResult == SOCKET_ERROR) {
        cout << "listen failed with error: " << WSAGetLastError() << "\n";
        closesocket(ListenSocket);
        WSACleanup();
        return 5;
    }

    cout << "Listening... Run the client program!\n";

    SOCKET ClientSocket = accept(ListenSocket, NULL, NULL);
    if (ClientSocket == INVALID_SOCKET) {
        cout << "accept failed with error: " << WSAGetLastError() << "\n";
        closesocket(ListenSocket);
        WSACleanup();
        return 6;
    }

    closesocket(ListenSocket);

    char message[DEFAULT_BUFLEN];
    do {
        iResult = recv(ClientSocket, message, DEFAULT_BUFLEN - 1, 0);
        if (iResult > 0) {
            message[iResult] = '\0';
            cout << "Client sent: " << message << "\n";

            // Перетворюємо у число
            int number = stoi(message);
            int replyNumber = number + 1;
            string reply = to_string(replyNumber);

            int iSendResult = send(ClientSocket, reply.c_str(), (int)reply.size(), 0);
            if (iSendResult == SOCKET_ERROR) {
                cout << "send failed with error: " << WSAGetLastError() << "\n";
                closesocket(ClientSocket);
                WSACleanup();
                return 7;
            }
        }
        else if (iResult == 0) {
            cout << "Connection closing...\n";
        }
        else {
            cout << "recv failed with error: " << WSAGetLastError() << "\n";
            closesocket(ClientSocket);
            WSACleanup();
            return 8;
        }
    } while (iResult > 0);

    shutdown(ClientSocket, SD_SEND);
    closesocket(ClientSocket);
    WSACleanup();
    cout << "Server shutting down!\n";
    return 0;
}