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How do I convert a string into an internet address?

  If you are reading a host's address from the command line, you may not
  know if you have an aaa.bbb.ccc.ddd style address, or a
  host.domain.com style address.  What I do with these, is first try to
  use it as a aaa.bbb.ccc.ddd type address, and if that fails, then do a
  name lookup on it.  Here is an example:

       /* Converts ascii text to in_addr struct.  NULL is returned if the
          address can not be found. */
       struct in_addr *atoaddr(char *address) {
         struct hostent *host;
         static struct in_addr saddr;

         /* First try it as aaa.bbb.ccc.ddd. */
         saddr.s_addr = inet_addr(address);
         if (saddr.s_addr != -1) {
           return &saddr;
         }
         host = gethostbyname(address);
         if (host != NULL) {
           return (struct in_addr *) *host->h_addr_list;
         }
         return NULL;
       }