I have an IPaddress and subnet mask, both in unsigned long; how can I AND both of these and check whether my incoming ipaddress (ip2) belongs to the same subnet or not?
like:
if (ip1 & subnet == ip2 & subnet)
then same subnet.
views:
112answers:
2
+2
A:
Use parentheses - the precedence levels are confusing:
if ((ip1 & subnet) == (ip2 & subnet))
...
The original code was effectively the same as:
if (ip1 & (subnet == ip2) & subnet)
...
Jonathan Leffler
2010-02-22 14:26:16
A good compiler should warn about this. GCC does, if invoked with `-Wall`.
Hans W
2010-02-22 14:30:49
oops! how can i miss it..:(
Ashish
2010-02-22 14:30:54
+1
A:
Just like you did it:
if ((ip1 & subnet) == (ip2 & subnet))
printf("same subnet 0%x", subnet);
(just added the () to insure the computation is done in the right order).
filofel
2010-02-22 14:27:10