Re: reason for code like this: "do { something } while (0)"

"Jesper Juhl" <jesper.juhl@xxxxxxxxx> · Mon, 15 May 2006 12:12:13 +0200

On 15/05/06, Rajat Jain <rajat.noida.india@xxxxxxxxx> wrote:
Hi,

I'm asking a pretty amateur question.

I've come accross code like this huge number of times in the kernel:

#define __set_task_state(tsk, state_value)              \
        do { (tsk)->state = (state_value); } while (0)

What is the reason to use do while loop if it is only meant to be
executed just once? Why not a simple:

#define __set_task_state(tsk, state_value)              \
        { (tsk)->state = (state_value); }

http://www.kernelnewbies.org/FAQ/DoWhile0

--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
Don't top-post  http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please      http://www.expita.com/nomime.html

--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/kernelnewbies/
FAQ:           http://kernelnewbies.org/faq/