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kotlinkotlin-multiplatform

How can I round a number in Kotlin-multiplatform without using external libraries?

I have a KMP project, and I want to round the doubles into the needed number of decimals, without implementing this in each platform, using primitive types and standard library is preferable.

Solution

  • You can create an extension function and use strings with functional methods like this:

    import kotlin.math.pow

fun Double.roundTo(dec: Int): Double {
    return toString().split('.').let {
        if (it.last().length <= dec) this
        else {
            val decimals = it.last().drop(it.last().length - dec)
            (it.first() + decimals).toDouble() / 10.0.pow(dec)
        }
    }
}

    Thanks for the feedback in the comments, I found a better way:

    import kotlin.math.pow
import kotlin.math.round

fun Double.roundTo(dec: Int): Double {
    return round(this * 10.0.pow(dec)) / 10.0.pow(dec)
}