Use inet_addr and gethostbyaddr. Example:
int main(int argc, char* argv[])
{
WSADATA d;
WSAStartup(MAKEWORD(2,2), &d);
char szIP[] = "1.2.3.4";
long ip = inet\_addr(szIP);
HOSTENT \*pHostent = gethostbyaddr((char\*)&ip,4,AF\_INET);
if (pHostent)
{
printf("%s is %s", szIP, pHostent->h\_name);
}
return 0;
}