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From: DervishD <raul@pleyades.net>
To: Joshua Stewart <joshua.stewart@comcast.net>
Cc: linux-kernel@vger.kernel.org
Subject: Re: A little explanation needed
Date: Sun, 22 Dec 2002 21:12:23 +0100	[thread overview]
Message-ID: <20021222201223.GC46@DervishD> (raw)
In-Reply-To: <1040535392.1518.3.camel@localhost.localdomain>

    Hi Joshua :)

> In otherwords, what's the use of a do{X}while(0) "loop" instead of
> just X.  I'm not the world's best trained C programmer, so forgive
> me if I sound stupid.

    First, you do not sound stupid at all.

    Second. The do...while use in macros is to avoid the 'swallow
semicolon' effect ;)) In other words, it makes the entire macro
appear as a single statement. This avoids problems with 'else'
constructs with macros that expand to multiple statements.

    Someplace in the GNU cpp documentation you can find a far better
explanation of this effect and why the do...while helps (it makes the
macro a single statement...).

    Hope that helps :)
    Raúl

      parent reply	other threads:[~2002-12-22 20:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-12-22  5:36 A little explanation needed Joshua Stewart
2002-12-22  5:35 ` Greg KH
2002-12-22 21:07   ` Joshua Stewart
2002-12-22 20:12 ` DervishD [this message]

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