The new ?? and ??? operators

[Arlen Albert Keshabyan]

Vladimir Panteleev Wrote:

> On Sun, 23 Sep 2007 18:34:09 +0300, Arlen Albert Keshabyan <arlen.albert at gmail.com> wrote:
> 
> [regarding ???]
> > The lvalue gets the first rvalue that evaluates to true (evaluation goes from left to right). 
> 
> So the result can only be boolean?
> In this case, I don't understand how
>   a = b ??? c ??? d;
> is different from
>   a |= b || c || d;
> 
> If b, c and d are false then a is unchanged.
> 
> -- 
> Best regards,
>  Vladimir                          mailto:thecybershadow at gmail.com


Consider this:

int v = 15;
int v2 = 30;

int a = v > 20 ??? v = 17 ??? v2 < 25 ??? 5;

in this case 'a' evaluates to 5 because none of the conditions evaluate to true except the last one. if you remove the last condition (??? 5) then 'a' stays 0 in this case.

If v2 = 23 then 'a' evaluates to 23;
If v = 27 then 'a' evaluates to 27;

etc.

It means that it takes a sequential rvalue, tests it against a condition and if the condition evaluates to true then it assigns that rvalue to lvalue. It does not mean you are restricted to boolean values only.