UDPClient.cpp

#include "stdafx.h"
#include <WinSock2.h>
#include <iostream>
#include <conio.h>

#define BUFSIZE 1024

using namespace std;


int _tmain(int argc, _TCHAR* argv[])
{
	WORD wVersion = MAKEWORD(1, 1);
	WSAData wsaData;
	WSAStartup(wVersion, &wsaData);

	SOCKET s;
	s = socket(AF_INET, SOCK_DGRAM, 0);

	char buf[BUFSIZE];
	cout << "Input ip-address:" << endl;
	cin >> buf;
	sockaddr_in sin;
	sin.sin_family = AF_INET;
	sin.sin_addr.s_addr = inet_addr(buf);
	sin.sin_port = htons(3245);
	int sin_len = sizeof(sin);

	cout << "Client started" << endl;
	int i = 0, rcv_len, snd_len;
	while (i++ < 3)
	{
		cout << "Input word:" << endl;
		cin >> buf;
		snd_len = sendto(s, buf, strlen(buf) + 1, 0, (SOCKADDR*)&sin, sin_len);
		if (snd_len > 0)
		{
			cout << "Sended message: " << buf << endl;
			rcv_len = recvfrom(s, buf, BUFSIZE - 1, 0, (SOCKADDR*)&sin, &sin_len);
			if (rcv_len > 0)
			{
				buf[rcv_len] = 0;
				cout << "Recieved messsage: " << buf << endl;
			}
			else
			{
				cout << "Recieving. Error code: " << WSAGetLastError() << endl;
				break;
			}
		}
		else
		{
			cout << "Sending. Error code: " << WSAGetLastError() << endl;
			break;
		}
	}
	
	closesocket(s);
	WSACleanup();
	_getch();

	return 0;
}

UDPServer.cpp

#include "stdafx.h"
#include <WinSock2.h>
#include <iostream>
#include <conio.h>

#define BUFSIZE 1024

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
	WORD wVersion = MAKEWORD(1, 1);
	WSAData wsaData;
	WSAStartup(wVersion, &wsaData);

	SOCKET s;
	s = socket(AF_INET, SOCK_DGRAM, 0);
	sockaddr_in sin;
	sin.sin_family = AF_INET;
	sin.sin_addr.s_addr = htonl(INADDR_ANY);
	sin.sin_port = htons(3245);
	if (bind(s, (SOCKADDR*)&sin, sizeof(sin)) != 0)
	{
		cout << "Binding. Error code: " << WSAGetLastError() << endl;
		_getch();
		return -1;
	}

	cout << "Server started" << endl;
	char buf[BUFSIZE];
	sockaddr_in sin_clt;
	int len_clt = sizeof(sockaddr);
	int i = 0, rcv_len, snd_len;
	while (i++ < 3)
	{
		int rcv_len = recvfrom(s, buf, BUFSIZE - 1, 0, (SOCKADDR*)&sin_clt, &len_clt);
		if (rcv_len > 0)
		{
			buf[rcv_len] = 0;
			cout << "Recieved message: " << buf << endl;
			_strupr_s(buf, strlen(buf) + 1);
			snd_len = sendto(s, buf, strlen(buf) + 1, 0, (SOCKADDR*)&sin_clt, len_clt);
			if (snd_len > 0)
				cout << "Sended message: " << buf << endl;
			else
			{
				cout << "Sending. Error code: " << WSAGetLastError() << endl;
				break;
			}
		}
		else
		{
			cout << "Recieving. Error code: " << WSAGetLastError() << endl;
			break;
		}
	}
	
	closesocket(s);
	WSACleanup();
	_getch();

	return 0;
}