Stupid questions about float operation

Question

Hi guys.
I have this code:
public class Stupida{
     public static void main(String args[]){
          float uno = 14.8210f;
          float due = 14.7110f;
          System.out.println("" + uno + " - " + due + " = " + (uno-due));
and this is the output:
14.821 - 14.711 = 0.10999966
Why the result it's not 0.110????
I tried with double, but the problem's the same.
I tried to use the "strictfp" modifier, but the compiler doesn't recognize it.
What should I do to get the exact result?
Thanx,
Pierlu.

Answer 1

and this is the output:
14.821 - 14.711 = 0.10999966
Why the result it's not 0.110????Because floating-point calcuations are inherently imprecise.
I tried with double, but the problem's the same.If you use double, the answer should be more accurate - you still can not expect it to be precise.
I tried to use the "strictfp" modifier, but the
compiler doesn't recognize it.Then you should get a new compiler.
Even so, the result you have posted is what I got using the strictfp modifier.
What should I do to get the exact result?I'm not going to go into detail because there are many threads in the forums that already cover this, and there's plently of good technical explainations on the Web - you just have to do a couple of simple searches.
In short, there are a couple of ways to get correct results. The safest is to use BigDecimal. Another (faster) option is to perform all your calculations using int or long, and keep track of where the decimal point should be, then add it in afterwards for display purposes (however, this requires a prior knowledge of a bounding range in which the figures you are operating on lie).