Can anyone please analyse this program for me (write a pseudocode for it).

[Tim Chase]

> /* $Id: dotquad.c 3529 2005-10-01 10:15:22Z dyoung $ */

Well, let's begin here.  You've got your python commenting style 
all wrong.  This alone won't parse as python.  I recommend using 
the standard "#" comment notation as described in the python docs.

> 	if (argc != 2 || !inet_aton(argv[1], &addr)) {
> 		usage(argv[0]);
> 	}
> 
> 	(void)printf("%s\n", inet_ntoa(addr));

Then, in your python code, you're using braces.  While there are 
conventions for doing that:

	if (conditions): # {
		statements
	#}

they clearly aren't being followed in your code, and given their 
optional nature, I suggest simply omitting them.  Second of all, 
you're calling non-idempotent functions in your "if" statement. 
Generally considered bad style.  Additionally, you never 
reference the sys.argv module/list of parameters, but still refer 
to argc (which should really be "len(sys.argv)"), and

The lines that look like they should be including your modules:

> #include <err.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/socket.h>
> #include <netinet/in.h>
> #include <arpa/inet.h>

appear to be commented out, as per above, using the standard "#" 
notation.  Additionally, the python syntax would be "import 
socket", not "include" followed by all this other rubbish with 
less-than and greater-than signs, and filename extensions.

This isn't rocket-surgery.  Both inet_aton() and inet_ntoa() 
function calls are in the socket module.  Call them accordingly:

 >>> import socket
 >>> print "\n".join([s for s in dir(socket) if 
s.startswith("inet_")])
inet_aton
inet_ntoa
 >>> help(socket.inet_aton)
Help on built-in function inet_aton in module _socket:

inet_aton(...)
     inet_aton(string) -> packed 32-bit IP representation

     Convert an IP address in string format (123.45.67.89) to the 
32-bit packed
     binary format used in low-level network functions.

 >>> help(socket.inet_ntoa)
Help on built-in function inet_ntoa in module _socket:

inet_ntoa(...)
     inet_ntoa(packed_ip) -> ip_address_string

     Convert an IP address from 32-bit packed binary format to 
string format
 >>> a = s.inet_aton("192.168.3.14")
 >>> a
'\xc0\xa9\x03\x0e'
 >>> s.inet_ntoa(a)
'192.168.3.14'

The rest is basic candy to get the command-line parameter and 
pass it in to aton and back again to ntoa.

I'm sure there are plenty of other problems, but this would be a 
good place to start...

-tkc