The intent is just to enclose the code of the macro in a block, so that if
you were to place this macro after an if() statement, and the macro was
multi-line, it would not break things.
eg.
#define crazy(a, b) \
a = b; \
b = a;
if(\*something*\)
crazy(a,b)
Look at this carefully, which line do you think is associated with the if()
here? Only a = b;, NOT b =a; !
but if the macro was written like this:
#define crazy(a, b) \
do { \
a = b; \
b = a; \
}
both the lines would be associated with the "true" case of if() above.
HTH,
Mayank
On Dec 26, 2007 11:44 PM, Maneesh Singhal <[EMAIL PROTECTED]> wrote:
> One more reason could be, by using do-while(0) thingy, one could use
> 'break' statement at any place just to come out of the macro at once.
>
> Thanks.
> Anupam Kapoor wrote:
> > sahlot arvind <[EMAIL PROTECTED]> wrote:
> > ,----
> > | > Recently I started looking into linux kernel and trying to
> understand
> > | > the code. I am working with linux-2.6.9. in file
> > | > include/llinux/list.h - I found something like this.
> > | >
> > | > #define INIT_LIST_HEAD(ptr) do { \
> > | > (ptr)->next = (ptr); (ptr)->prev = (ptr); \
> > | > } while (0)
> > | >
> > | >
> > | > My question is why do we use a loop when we actually know that it is
> > | > not going to execute more than once? Cannot we simply do -
> > `----
> > see: http://kernelnewbies.org/FAQ/DoWhile0
> >
> > anupam
> >
> > --
> > To unsubscribe from this list: send an email with
> > "unsubscribe kernelnewbies" to [EMAIL PROTECTED]
> > Please read the FAQ at http://kernelnewbies.org/FAQ
> >
> >
> >
>
> --
> To unsubscribe from this list: send an email with
> "unsubscribe kernelnewbies" to [EMAIL PROTECTED]
> Please read the FAQ at http://kernelnewbies.org/FAQ
>
>
--
KTHXBAI
-Mayank
