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Subject: Re: Range-aware modulo operator -%
Newsgroups: comp.lang.c,comp.lang.c++
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From: Bart <bc@freeuk.com>
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Xref: csiph.com comp.lang.c:139313 comp.lang.c++:62682

On 01/01/2019 00:44, Keith Thompson wrote:
> Bart <bc@freeuk.com> writes:
> [...]
>> If you write if(x), while(x), or for(;x;), then it automatically applies
>> the effective equivalent of !! to give a true (x!=0) or false (x==0)
>> result. (The same with (x && y) and any such combinations.)
> [...]
> 
> That's one way to describe it.  It's now how the standard describes it.
> 
> For example, the description of the "if" statement says "the first
> substatement is executed if the expression compares unequal to 0",
> which I find clearer and simpler than your reformulation.

That's the whole expression. It doesn't really explain how a complex 
expression ends up as zero or not zero. Or the difference between A && B 
when B is 'b==x' and when B is just 'b'.

 From a design and implementation point of view, you have to go into it 
in more detail.

Perhaps simpler might be to say that operands of if(), while(), for(;;), 
&&, || unary !, need to be either already Bool, or have to be converted 
to Bool.

It is that last that can also be done with !!.

-- 
bart