PeteUDPClient

#define _WINSOCK_DEPRECATED_NO_WARNINGS
#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>
#include "conio.h"

#pragma comment (lib, "Ws2_32.lib")
#pragma comment (lib, "Mswsock.lib")
#pragma comment (lib, "AdvApi32.lib")

#define SERVER_IP_ADDRESS "127.0.0.1"       // IPv4 address of server
#define BUFFER_SIZE 512                     // Size of buffer that will be used for sending and receiving messages to client


int main()
{
    // Server address structure
    sockaddr_in serverAddress;

    // Size of server address structure
    int sockAddrLen = sizeof(serverAddress);

    // Buffer that will be used for sending and receiving messages to client
    char dataBuffer[BUFFER_SIZE];

    // WSADATA data structure that is used to receive details of the Windows Sockets implementation
    WSADATA wsaData;

    // Initialize windows sockets for this process
    int iResult = WSAStartup(MAKEWORD(2,2), &wsaData);

    // Check if library is succesfully initialized
    if (iResult != 0)
    {
        printf("WSAStartup failed with error: %d\n", iResult);
        return 1;
    }

   // Initialize memory for address structure
    memset((char*)&serverAddress, 0, sizeof(serverAddress));

    // Read server's port number
    printf("Enter server port number (15011 or 15012):\n");
    gets_s(dataBuffer, BUFFER_SIZE);
    unsigned long serverPort = atoi(dataBuffer);

     // Initialize address structure of server
    serverAddress.sin_family = AF_INET;                             // IPv4 address famly
    serverAddress.sin_addr.s_addr = inet_addr(SERVER_IP_ADDRESS);   // Set server IP address using string
    serverAddress.sin_port = htons(serverPort);                 // Set server port

    // Create a socket
    SOCKET clientSocket = socket(AF_INET,      // IPv4 address famly
                                 SOCK_DGRAM,   // Datagram socket
                                 IPPROTO_UDP); // UDP protocol

    // Check if socket creation succeeded
    if (clientSocket == INVALID_SOCKET)
    {
        printf("Creating socket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

   while (true)
   {

        printf("Enter message to send:\n");

        // Read string from user into outgoing buffer
        gets_s(dataBuffer, BUFFER_SIZE);

        //close client if end  message is entered
        if ( !strcmp(dataBuffer,"end"))
        {
         printf("Client has finished. It's closing.\n");
             break;
        }

        // Send message to server
     iResult = sendto(clientSocket,                     // Own socket
                     dataBuffer,                        // Text of message
                     strlen(dataBuffer),                // Message size
                     0,                                 // No flags
                     (SOCKADDR *)&serverAddress,        // Address structure of server (type, IP address and port)
                     sizeof(serverAddress));            // Size of sockadr_in structure

        // Check if message is succesfully sent. If not, close client application
        if (iResult == SOCKET_ERROR)
        {
        printf("sendto failed with error: %d\n", WSAGetLastError());
        closesocket(clientSocket);
        WSACleanup();
        return 1;
        }

   }

    // Only for demonstration purpose
    printf("Press any key to exit: ");
    _getch();

    // Close client application
    iResult = closesocket(clientSocket);
    if (iResult == SOCKET_ERROR)
    {
        printf("closesocket failed with error: %d\n", WSAGetLastError());
        WSACleanup();
        return 1;
    }

    // Close Winsock library
    WSACleanup();

    // Client has succesfully sent a message
    return 0;
}