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From: Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: Sequencing guarantees for macro versions of standard functions
Date: Sun, 23 Jan 2022 23:50:33 -0800
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Andrey Tarasevich <andreytarasevich@hotmail.com> writes:
> On 1/23/2022 7:56 PM, Andrey Tarasevich wrote:
>> On 1/23/2022 7:36 PM, Tim Rentsch wrote:
>>>
>>> However, the suggested rewrite has different semantics than the
>>> previous single assignment with function call.  If we want to
>>> keep the same semantics but still be able to use the macro
>>> form (but without any sequencing issues), a different writing
>>> is needed, as for example
>>>
>>>      x = modf( x, (double[]){ 0 } );
>>>
>>> Writing the call this way should make it obvious that the value
>>> stored in/through the second argument is ignored and discarded.
>> That would be
>>        x = modf( x, &(double[]){ 0 } );
>> 
>
> Opps, my sitake. Sorry, I missed the `[]` part.
>
> Of course, your original variant is correct. Although I don't see the
> point of bringing arrays into the picture. One can just do
>
>   x = modf( x, &(double){ 0 } );

My preference would be:

    double ignored;
    x = modf(x, &ignored);

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Working, but not speaking, for Philips
void Void(void) { Void(); } /* The recursive call of the void */