Re: g++ 3.4.2 strange behavior

[Paul Schneider]

Ulrich Eckhardt wrote:
> Paul Schneider wrote:
> [ (1000.0-0.0)/0.001 yields 99999 ]
>
> > where it should be 100000 straight in my opinion. What am I doing wrong.
>
>
> Try representing 0.001 in binary, it can't be done accurately, just as 1/3
> can't in decimal. IOW, the computer has to use a value slightly lower or
> higher, which is why your result differs from what you expect. 
> The reason it didn't do so with the other number might be that they were
> already computed at compile-time or with higher precision or with a
> different algorithm. 
>
> Uli
I am well aware of the real number representation problem. I was not 
aware of the fact that ( I just tried it):

double b = 1000.0;
double a = 0.0;
double c = 0.01;

static_cast<size_t>((b-a)/c);

is different from

static_cast<size_t>((1000.0 - 0.0)/0.01);

as you just suggested. Personally I find this very disturbing. Thanks 
for your answer.

cheers,

Paul