I use next way and it work correct always for me

Qt Code: 
  1. char hostname[255];
  2. int lhnr_res = gethostname(hostname, 255); 
  3.  
  4. if(lhnr_res)
  5.   printf("Can't resolve hostname!\n");
  6. else		
  7.   printf("Host name is '%s'\n", hostname);
  8.  
  9. hostent *lh= gethostbyname(hostname); 
  10.  
  11. if(!lh)
  12.   printf("Can't resolve ipaddress!\n");
  13. else
  14. {
  15.   QStringList ipList;
  16.   for(int i=0; ;i++)
  17.   {
  18.     char *ipadr=lh->h_addr_list[i];
  19.  
  20.     if(ipadr)
  21.     {
  22.       QString sIP;
  23.       sIP.sprintf("%d.%d.%d.%d", (unsigned char)ipadr[0], (unsigned char)ipadr[1], (unsigned char)ipadr[2], (unsigned char)ipadr[3]);
  24.       ipList.append(sIP);
  25.       printf("IP addres is %s:\n", sIP.data());
  26.     }
  27.     else
  28.       break;
  29.    }
  30. }
To copy to clipboard, switch view to plain text mode