Calculating subnet wiht netmask...

[sam]

Hi,

This is a C programming specific with TCP/IP relation.
Supposed I have two string (char *) variables with the following assignment:
ip_str = "10.1.2.3"
netmask_str = "255.255.0.0"

How can I use C programming technique to get the subnet 10.1.0.0?

I tried to use "struct in_addr", but not sure how to start writing a
simple code for it?

Is there any simple C code that I can follow in this regard?

Thanks
Sam

 

[Victor Bazarov]

This is a C programming specific with TCP/IP relation.

This is a C++ newsgroup, and TCP/IP is off-topic.

However, if you have 2 strings, where one is an encoded number
and the other is an encoded mask, you need to

(a) convert the number into an unsigned long
(b) convert the mask into an unsigned long
(c) perform bitwise AND on them
(d) convert the result back into a string

Use 'sscanf' to convert numbers from a string, and 'sprintf' to
convert back.

V