Re: GCC 3.4 Heads-up

[Bill Davidsen <davidsen@tmr.com>]

Krzysztof Halasa wrote:
> Bill Davidsen <davidsen@tmr.com> writes:
> 
> 
>>I would probably write
>>   ( a ? b : c ) = d;
>>instead, having learned C when some compilers parsed ? wrong without
>>parens. Actually I can't imagine writing that at all, but at least
>>with parens humans can read it easily. Ugly code.
>>
>>Your suggestion is not portable, if b or c are declared "register"
>>there are compilers which will not allow taking the address, and gcc
>>will give you a warning.
> 
> 
> One can write as well:
> 
> if (a)
>         b = d;
> else
>         c = d;
> 
> Might be more readable and it is what the compiler does.

Since that's a matter of taste I can't disagree. The point was that the 
original post used
   *(a ? &b : &c) = d;
which generates either warnings or errors if b or c is a register 
variable, because you are not allowed to take the address of a register. 
It seems gcc does it anyway by intuiting what you mean, but it's not 
portable in the sense of being error-free code.

It was a nit, I didn't mean to start a controversy, although if "d" is 
actually a complex expression it is certainly less typing as I showed 
it, and prevents a future maintainer from changing one RHS and not the 
other. That's defensive programming.


-- 
bill davidsen <davidsen@tmr.com>
   CTO TMR Associates, Inc
   Doing interesting things with small computers since 1979