Question

I am unable to understand why C++ division behaves the way it does. I have a simple program which divides 1 by 10 (using VS 2003)

double dResult = 0.0;
dResult = 1.0/10.0;

I expect dResult to be 0.1, However i get 0.10000000000000001

1. Why do i get this value, whats the problem with internal representation of double/float
2. How can i get the correct value?

Thanks.

Answer 1

Because all most modern processors use binary floating-point, which cannot exactly represent 0.1 (there is no way to represent 0.1 as m * 2^e with integer m and e).

If you want to see the “correct value”, you can print it out with e.g.:

printf("%.1f\n", dResult);