C / C++ / MFC

#include <windows.h>
#include <winsock.h>
#include <stdio.h>

#define NETWORK_ERROR -1
#define NETWORK_OK     0

void ReportError(int, const char *);


int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR lpCmd, int nShow)
{
	WORD sockVersion;
	WSADATA wsaData;
	int nret;
    struct in_addr addr;
    addr.s_addr = inet_addr("127.0.0.1");

	sockVersion = MAKEWORD(1, 1);


	// Initialize Winsock as before
	WSAStartup(sockVersion, &wsaData);


	// Store information about the server
	LPHOSTENT hostEntry;

	hostEntry = gethostbyaddr((char *) &addr, 4, AF_INET);	// Specifying the server by its name;
							// another option: gethostbyaddr()

	if (!hostEntry)
	{
		nret = WSAGetLastError();
		ReportError(nret, "gethostbyaddr()");	// Report the error as before

		WSACleanup();
		return NETWORK_ERROR;
	}


	// Create the socket
	SOCKET theSocket;

	theSocket = socket(AF_INET,			// Go over TCP/IP
			   SOCK_STREAM,			// This is a stream-oriented socket
			   IPPROTO_TCP);		// Use TCP rather than UDP
	if (theSocket == INVALID_SOCKET)
	{
		nret = WSAGetLastError();
		ReportError(nret, "socket()");

		WSACleanup();
		return NETWORK_ERROR;
	}


	// Fill a SOCKADDR_IN struct with address information
	SOCKADDR_IN serverInfo;

	serverInfo.sin_family = AF_INET;

	// At this point, we've successfully retrieved vital information about the server,
	// including its hostname, aliases, and IP addresses.  Wait; how could a single
	// computer have multiple addresses, and exactly what is the following line doing?
	// See the explanation below.

	serverInfo.sin_addr = *((LPIN_ADDR)*hostEntry->h_addr_list);

	serverInfo.sin_port = htons(80);		// Change to network-byte order and
							// insert into port field


	// Connect to the server
	nret = connect(theSocket, (LPSOCKADDR)&serverInfo, sizeof(struct sockaddr));

	if (nret == SOCKET_ERROR)
	{
		nret = WSAGetLastError();
		ReportError(nret, "connect()");

		WSACleanup();
		return NETWORK_ERROR;
	}

    MessageBoxA(NULL, "Great, it is good", "socket Successful", MB_OK);
	// Successfully connected!
    

	// Send/receive, then cleanup:
	closesocket(theSocket);
	WSACleanup();
    return NETWORK_OK;
}


void ReportError(int errorCode, const char *whichFunc)
{
   char errorMsg[92];					// Declare a buffer to hold
							// the generated error message
   
   ZeroMemory(errorMsg, 92);				// Automatically NULL-terminate the string

   // The following line copies the phrase, whichFunc string, and integer errorCode into the buffer
   sprintf_s(errorMsg, "Call to %s returned error %d!", (char *)whichFunc, errorCode);

   MessageBoxA(NULL, errorMsg, "socketIndication", MB_OK);
}