client

#include <iostream>
#include <string>
#include <cstring>

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

int main() {
    int clientSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (clientSocket < 0) {
        std::cout << "socket() failed\n";
        return 1;
    }

    sockaddr_in serverAddr{};
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(5555);
    inet_pton(AF_INET, "127.0.0.1", &serverAddr.sin_addr);

    if (connect(clientSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) {
        std::cout << "connect() failed (server running?)\n";
        close(clientSocket);
        return 1;
    }

    std::cout << "Connected to server.\n";
    std::cout << "Type: як справи / котра година / exit\n\n";

    while (true) {
        std::cout << "You: ";
        std::string text;
        std::getline(std::cin, text);

        std::string out = text + "\n";
        send(clientSocket, out.c_str(), out.size(), 0);

        char buffer[1024];
        std::memset(buffer, 0, sizeof(buffer));
        ssize_t bytes = recv(clientSocket, buffer, sizeof(buffer) - 1, 0);

        if (bytes <= 0) {
            std::cout << "Server disconnected\n";
            break;
        }

        std::string answer(buffer);
        while (!answer.empty() && (answer.back() == '\n' || answer.back() == '\r')) {
            answer.pop_back();
        }

        std::cout << "Server: " << answer << "\n\n";

        if (text == "exit") {
            break;
        }
    }

    close(clientSocket);
    return 0;
}

server

#include <iostream>
#include <string>
#include <cstring>
#include <ctime>

#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>

int main() {
    int serverSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (serverSocket < 0) {
        std::cout << "socket() failed\n";
        return 1;
    }

    int opt = 1;
    setsockopt(serverSocket, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    sockaddr_in serverAddr{};
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(5555);
    serverAddr.sin_addr.s_addr = INADDR_ANY;

    if (bind(serverSocket, (sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) {
        std::cout << "bind() failed\n";
        close(serverSocket);
        return 1;
    }

    if (listen(serverSocket, 5) < 0) {
        std::cout << "listen() failed\n";
        close(serverSocket);
        return 1;
    }

    std::cout << "Server listening on port 5555...\n";
    std::cout << "Waiting for client...\n";

    sockaddr_in clientAddr{};
    socklen_t clientSize = sizeof(clientAddr);
    int clientSocket = accept(serverSocket, (sockaddr*)&clientAddr, &clientSize);

    if (clientSocket < 0) {
        std::cout << "accept() failed\n";
        close(serverSocket);
        return 1;
    }

    std::cout << "Client connected!\n";

    char buffer[1024];

    while (true) {
        std::memset(buffer, 0, sizeof(buffer));
        ssize_t bytes = recv(clientSocket, buffer, sizeof(buffer) - 1, 0);

        if (bytes <= 0) {
            std::cout << "Client disconnected\n";
            break;
        }

        std::string msg(buffer);

        while (!msg.empty() && (msg.back() == '\n' || msg.back() == '\r')) {
            msg.pop_back();
        }

        std::cout << "Client: " << msg << "\n";

        std::string answer;

        if (msg == "exit") {
            answer = "bye";
            std::string out = answer + "\n";
            send(clientSocket, out.c_str(), out.size(), 0);
            break;
        }
        else if (msg == "як справи" || msg == "як справи?") {
            answer = "чудово";
        }
        else if (msg == "котра година" || msg == "котра година?") {
            std::time_t t = std::time(nullptr);
            std::tm lt{};
            localtime_r(&t, &lt);
            char timeBuf[6];
            std::snprintf(timeBuf, sizeof(timeBuf), "%02d:%02d", lt.tm_hour, lt.tm_min);
            answer = timeBuf;
        }
        else {
            answer = "не розумію";
        }

        std::string out = answer + "\n";
        send(clientSocket, out.c_str(), out.size(), 0);
    }

    close(clientSocket);
    close(serverSocket);
    return 0;
}