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From: David Brown <david.brown@hesbynett.no>
Newsgroups: comp.lang.c
Subject: Re: Concatenated if and preprocessor
Date: Sat, 15 Mar 2025 17:32:32 +0100
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On 14/03/2025 23:29, Tim Rentsch wrote:
> Richard Harnden <richard.nospam@gmail.invalid> writes:
> 
>> On 14/03/2025 21:10, Keith Thompson wrote:
>>
>>> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:
>>>
>>>> Richard Harnden <richard.nospam@gmail.invalid> writes:
>>>>
>>>>> On 14/03/2025 16:44, Tim Rentsch wrote:
>>>>>
>>>>>>      for(  int just_once = 1;  just_once;  just_once = 0  ){
>>>>>
>>>>> Any reason not to say ...
>>>>>
>>>>> do {
>>>>>       ...
>>>>> } while (0);
>>>>>
>>>>> ... ?
>>>>
>>>> In fact using do/while(0) is what I first wrote.  But then
>>>> I thought, oh wait, what if an overzealous compiler gives
>>>> a warning because the while() expression is always false? :-/
>>
>> That would break a lot of macros :)
>>
>>> [...]
>>
>> Hmm, clang with -Weverything is okay with:
>>    do { ... } while (0);
>>
>> But not with:
>>    if ( 0 ) { ... }
>>
>> But it's okay with:
>>    if ( (0) ) { ... }
> 
> These examples illustrate why I have the reaction I do.  That
> plus the lack of clarity as to what the OP's actual requirements
> are explains my decision to use a for() rather than do/while(0).

I think your "for" solution would raise far more questions to any reader 
than idiomatic "do ... while (0)" would, or even if ((0)).  I really 
don't understand your reactions at all.

But I fully agree that it would be a lot easier to give the OP a good 
answer if he explained his requirements and situation better.