A simple application using I/O Completion Ports and WinSock

#include "stdafx.h"

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>
#include <winsock2.h>

int main(int argc, char* argv[])
{
     //Validate the input
     if (argc < 3) 
     {
          printf("\nUsage: %s hostname port.", argv[0]);
          return 1; //error
     }
     
     // Initialize Winsock
     WSADATA wsaData;
     
     int nResult = WSAStartup(MAKEWORD(2,2), &wsaData);
     
     if (NO_ERROR != nResult)
     {
          printf("\nError occurred while executing WSAStartup().");
          return 1; //error
     }
     else
     {
          printf("\nWSAStartup() successful.");
     }
     
     SOCKET Socket;
     int nPortNo;
     struct sockaddr_in ServerAddress;
     struct hostent *Server;
     
     char szBuffer[256];
     
     //Port number will be supplied as a commandline argument
     nPortNo = atoi(argv[2]);
     
     //Create a socket
     Socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
     
     if (INVALID_SOCKET == Socket) 
     {
          printf("\nError occurred while opening socket: %ld.", WSAGetLastError());
          goto error;
     }
     else
     {
          printf("\nsocket() successful.");
     }
     
     //Server name will be supplied as a commandline argument
     //Get the server details
     Server = gethostbyname(argv[1]);
     
     if (Server == NULL) 
     {
          closesocket(Socket);
          printf("\nError occurred no such host.");
          goto error;
     }
     else
     {
          printf("\ngethostbyname() successful.");
     }
     
     //Cleanup and Init with 0 the ServerAddress
     ZeroMemory((char *) &ServerAddress, sizeof(ServerAddress));
     
     ServerAddress.sin_family = AF_INET;
     
     //Assign the information received from gethostbyname()
     CopyMemory((char *)&ServerAddress.sin_addr.s_addr, 
          (char *)Server->h_addr,
          Server->h_length);
     
     ServerAddress.sin_port = htons(nPortNo); //comes from commandline
     
     //Establish connection with the server
     if (SOCKET_ERROR == connect(Socket, reinterpret_cast<const struct sockaddr *>(&ServerAddress),sizeof(ServerAddress))) 
     {
          closesocket(Socket);
          
          printf("\nError occurred while connecting.");
          goto error;
     }
     else
     {
          printf("\nconnect() successful.");
     }
     
     //Cleanup and Init with 0 the szBuffer
     ZeroMemory(szBuffer,256);
     
     printf("\nPlease enter message to be sent to server: ");
     
     //Read the message from server
     fgets(szBuffer,255,stdin);
     
     int nBytesSent;
     int nBytesRecv;
     
     //Send the message to the server
     nBytesSent = send(Socket, szBuffer, strlen(szBuffer), 0);
     
     if (SOCKET_ERROR == nBytesSent) 
     {
          closesocket(Socket);
          
          printf("\nError occurred while writing to socket.");
          goto error;
     }
     else
     {
          printf("\nsend() successful.");
     }
     
     //Cleanup and Init with 0 the szBuffer
     ZeroMemory(szBuffer,256);
     
     //Get the message from the server
     nBytesRecv = recv(Socket, szBuffer, 255, 0 );
     
     if (SOCKET_ERROR == nBytesRecv) 
     {
          closesocket(Socket);
          
          printf("\nError occurred while reading from socket.");
          goto error;
     }
     else
     {
          printf("\nrecv() successful.");
     }
     
     //Display the server message
     printf("\n%s", szBuffer);
     
     //Close the socket
     closesocket(Socket);
     
     //Cleanup Winsock
     WSACleanup();
     return 0; //success
     
error:
     // Cleanup Winsock
     WSACleanup();
     return 1; //error
}