Date: Thu, 12 Mar 1998 19:39:39 -0800 (PST) From: "Jonathan M. Bresler" <jmb> To: shimon@simon-shapiro.org Cc: freebsd-current@FreeBSD.ORG Subject: Re: A question about sys/sys/queue.h Message-ID: <199803130339.TAA10294@hub.freebsd.org> In-Reply-To: <XFMail.980312191745.shimon@simon-shapiro.org> from Simon Shapiro at "Mar 12, 98 07:17:45 pm"
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Simon Shapiro wrote:
> Why was the definition of some macros changed
> from:
>
> #define FOO { ... }
>
> to:
>
> #define FOO do { ... } while(0)
>
> I thought these are the same...
>
the difference lies in how you use them.
in the first case one writes "FOO"
in the second "FOO;"
^
make a macro act more like a statement.
imagine the code around the macro
rather then the macro itself.
first saw this in _C_traps_and_pitfalls_
by andrew koenig (sp?)
jmb
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