I'm writing a simple program to convert an IP address to a hostname, but I'm having trouble with the function GetHostByAddr (found in winsock.h (windows) or netdb.h (linux/unix)). The function takes three arguments (const char FAR * addr,int len, int type) len=4 and type=AF_INET. I've tried simply passing a string (ie: "127.0.0.1") as the addr argument, but it doesn't work. I think it wants the address in network byte order but I can't figure it out. If you have an idea what the problem is (or source code, or a suggestion) please tell me. I will post my source in my next message.

<p>
<font color="#008000">#include <stdio.h><br>
<br>
#include <conio.h><br>
<br>
#include <winsock.h></font><br>
<br>
<br>
<br>
<br>
<br>
<strong>void</strong> main(int argc, char * argv[])<br>
<br>
<strong>{</strong><br>
<br>
<br>
<br>
&nbsp;&nbsp; <strong>if</strong>(argc==2)<br>
<br>
&nbsp;&nbsp;&nbsp; <strong>{</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; WSADATA wsaData<strong>;</strong><br>
<br>
<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>if</strong>(WSAStartup(MAKEWORD( 1, 1 ),<br>
&amp;wsaData)==0)<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>{</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<font color="#FF0000"><br>
/* Define addr here */</font><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>struct</strong><br>
hostent *hostinfo=gethostbyaddr(addr, 4, AF_INET)<strong>;</strong><br>
<br>
<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>if</strong><br>
(hostinfo!=NULL)<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>{</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>
printf("%s", hostinfo->h_name)<strong>;</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>}</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>else</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>{</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>
printf("%s", "error")<strong>;</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>}</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <strong>}</strong><br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; getche()<strong>;</strong><br>
<br>
&nbsp;&nbsp;&nbsp; <strong>}</strong><br>
<br>
<strong>}</strong></p>

Damn HTML parsing!<p>
#include <stdio.h><br>
#include <conio.h><br>
#include <winsock.h><p>
<br>
void main(int argc, char * argv[])<br>
{<br>
if (argc==2)<br>
{<br>
WSADATA wsaData;<br>
if (WSAStartup(MAKEWORD( 1, 1 ), &wsaData)==0)<br>
{<br>
/* Define addr here */<br>
struct hostent *hostinfo=gethostbyaddr(addr, 4, AF_INET);<br>
if (hostinfo!=NULL)<br>
{<br>
printf("%s", hostinfo->h_name);<br>
}<br>
else<br>
{<br>
printf("%s", "error");<br>
}<br>
}<br>
getche();<br>
}<br>
}

includes: <br>
stdio.h<br>
conio.h<br>
winsock.h

includes: <br>
stdio.h<br>
conio.h<br>
winsock.h