How to subtract 2 floats in Kotlin

Question

I have a very strange problem in my Kotlin app :

14.9 - 12.8 == 2.0999994

I also tried to do :

var1 = 14.9
var2 = 12.8
var1.minus(var2)

but I strangely get the same result.

How can I subtract 2 floats in Kotlin and getting a decent value, like 2.1 in this case ?

Possible duplicate of [Retain precision with double in Java](https://stackoverflow.com/questions/322749/retain-precision-with-double-in-java) — Kevin Cruijssen, Aug 21 '18 at 09:32
If the numbers are really of type float, the result is OK. You can expect only about 6 decimal digits accuracy. — Henry, Aug 21 '18 at 09:34
Blackbelt I declare them as float. I am going to try to cast them in double. Thanks ! — Mathieu, Aug 21 '18 at 09:37
@Elynad `double` will still give floating point inaccuracies same as `float`. You'll have to use `BigDecimal` for actual precision. — Kevin Cruijssen, Aug 21 '18 at 09:40

score 0 · Answer 1 · answered Aug 21 '18 at 09:33

0

This is a floating point error if you are not into financial calculations then you can use

var var1 = 14.9
var var2 = 12.8
var var3 = var1.minus(var2)
println("%.2f".format(var3))

Else try BigDecimal

answered Aug 21 '18 at 09:33

Dev

Unfortunatly I don't want to just print or display the result, I also need to do some calculations with it. But I am going to try the BigDecimal thing, thanks for the tip ! – Mathieu Aug 21 '18 at 09:35

1 Answers1