Date: Thu, 12 Mar 1998 21:51:07 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: "Jonathan M. Bresler" <jmb@FreeBSD.ORG> Cc: freebsd-current@FreeBSD.ORG Subject: Re: A question about sys/sys/queue.h Message-ID: <XFMail.980312215107.shimon@simon-shapiro.org> In-Reply-To: <199803130339.TAA10294@hub.freebsd.org>
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On 13-Mar-98 Jonathan M. Bresler wrote:
> 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;"
cute. Wonder what the compiled code looks like...
Thanx
> ^
> 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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----------
Sincerely Yours,
Simon Shapiro
Shimon@Simon-Shapiro.ORG Voice: 503.799.2313
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