Why isn't this expression const?

[Daniel Keep]

Brian Palmer wrote:
> Frits van Bommel Wrote:
> 
>> Silverling wrote:
>>> Brian Palmer Wrote:
>>>
>>>> ...
>> I can't get it to compile for ints either...
> 
> Sorry, now that I read what I wrote I wasn't clear. I didn't mean changing float to int, I meant doing:
> 
>  const int a = 5;
>  const int b = a*-1;
> 
> works as expected.
> 
>>> Try
>>> const Vector3 ROT_FORCE_CCW = [0, 400_000, 0];
>>> const Vector3 ROT_FORCE_CW  = [0, ROT_FORCE_CCW.y*-1, 0];
>>>
>>> That's how you init an array. I assume that Vector3 is an alias for float[3].
>> It's not an array. Look at the first line of his code: it's a struct.
> 
> Yes, thanks.

Look at the error you got: the compiler is converting ROT_FORCE_CCW.y
into *(&ROT_FORCE_CCW + 4), and since pointers can't be used at
compile-time, the evaluation fails.

A workaround might be to store 400_000 in a named constant, and use that
instead.

const ROT_FORCE = 400_000.;
const Vector3 ROT_FORCE_CCW = {0, ROT_FORCE, 0};
const Vector3 ROT_FORCE_CW  = {0, -ROT_FORCE, 0};

	-- Daniel

-- 
int getRandomNumber()
{
    return 4; // chosen by fair dice roll.
              // guaranteed to be random.
}

http://xkcd.com/

v2sw5+8Yhw5ln4+5pr6OFPma8u6+7Lw4Tm6+7l6+7D
i28a2Xs3MSr2e4/6+7t4TNSMb6HTOp5en5g6RAHCP  http://hackerkey.com/