project1.cpp

网络编程的一些实例

#pragma hdrstop
#include <condefs.h>
#include <stdio.h>
#include <windows.h>

LPSTR GetHostIpAddress();
//---------------------------------------------------------------------------
#pragma argsused
int main(int argc, char* argv[])
{
 char *IP;
 IP=GetHostIpAddress();
 printf("ip=%s\n",IP);
 getchar();
 return 0;
}
//===========================================
LPSTR GetHostIpAddress()
{
 struct hostent *thisHost;
 struct in_addr in;
 char MyName[80];
 char *Ip,*ptr;

 WORD wVersionRequested;
 WSADATA wsaData;
 int err;
 wVersionRequested = MAKEWORD( 2, 0 );
 err = WSAStartup( wVersionRequested, &wsaData );
 if ( err != 0 )
   {
    /* Tell the user that we couldn't find a usable */
    /* WinSock DLL.                                  */
    return NULL;
   }
 /* Confirm that the WinSock DLL supports 2.0.*/
/* Note that if the DLL supports versions greater    */
/* than 2.0 in addition to 2.0, it will still return */
/* 2.0 in wVersion since that is the version we      */

/* requested.                                        */
 
if ( LOBYTE( wsaData.wVersion ) != 2 ||
        HIBYTE( wsaData.wVersion ) != 0 )
  {
    /* Tell the user that we couldn't find a usable */
    /* WinSock DLL.                                  */
    WSACleanup( );
    return NULL;
  }

 if(gethostname(MyName,80)==SOCKET_ERROR)
   return NULL;

 if(!(thisHost=gethostbyname(MyName)))
   return NULL;
 memset((void *)&in,sizeof(in),0);
 in.s_addr=*((unsigned long *)thisHost->h_addr_list[0]);
 if(!(ptr=inet_ntoa(in)))
   return NULL;
 WSACleanup( );
 Ip=new char[strlen(ptr)+1];
 strcpy(Ip,ptr);
 return Ip;
}