Question

I have following simple code:

for (float i=0; i<1f; i+=0.1) {
    System.out.println(i);
}

I have just got following results:

0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.70000005
0.8000001
0.9000001

But I can’t understand why there is. Please, I hope you can tell me. Thank you.

Answer 1

From The Floating-Point Guide:

Why don’t my numbers, like 0.1 + 0.2 add up to a nice round 0.3, and
instead I get a weird result like 0.30000000000000004?

Because internally, computers use a format (binary floating-point)
that cannot accurately represent a number like 0.1, 0.2 or 0.3 at all.

When the code is compiled or interpreted, your “0.1” is already
rounded to the nearest number in that format, which results in a small
rounding error even before the calculation happens.