Unity 3D & C# : Adding a decimal to a float, rounding up

Question

So I have created a simple script where, I have a float variable "rps", which starts off at 0.001.

Every second I add 0.0001 to this variable.

When I output the variable to the screen in Unity 3D, why does it come out as a really long decimal, like 0.001099999999?

So instead of adding 0.0001 it adds 0.00009999999999, when that is 100% not what I am adding.

Is there anyway to fix this, or is it just a bug within Unity or C#, if I am unable to fix it, is there an easy way to round it, as I have searched the internet, and it all looks like a lot of code, that doesn't seem necessary. Thanks for any help

Possible duplicate of [C# float magically changing value](https://stackoverflow.com/questions/4542575/c-sharp-float-magically-changing-value) — Ruzihm, Oct 24 '18 at 20:47
@Ruzihm thanks for guiding me to the duplicte, did not see that one, and sorry about accidentally putting it as C++, been using a lot of C++ for robotics recently — , Oct 24 '18 at 20:49
Possible duplicate of [Is floating point math broken?](https://stackoverflow.com/questions/588004/is-floating-point-math-broken) — brady, Oct 24 '18 at 20:49

score 1 · Answer 1 · answered Oct 24 '18 at 20:48

1

try this:

float rounded = (float)(Math.Round((double)f, 4);

you will need to adjust it a little but you should get the idea.

answered Oct 24 '18 at 20:48

Technivorous

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sorry was c++ before. fixed it. this will round `f` to the 4th place. making your .00019999 a whole number.(.0002) – Technivorous Oct 24 '18 at 20:51

score 0 · Answer 2 · answered Oct 24 '18 at 21:14

used fixed point or integers if you need that level of precision.

float precision = 10000f; // 1.0000
int rps = (int)(0.001f * precision); // or rps = 10
int inc = (int)(0.0001f * precision); // or inc = 1

while (...)
{
    rps += inc;

    float rps_as_float = rps / precision;
}

Unity 3D & C# : Adding a decimal to a float, rounding up

2 Answers2