Hello , how to write this function is best way ? ```fun String?.trimTrailingZeros(): String? { i...

# codereview

[KV]

Hello ,
how to write this function is best way ?

fun String?.trimTrailingZeros(): String? {
    if (isNullOrEmpty() || this!!.indexOf(".") < 0) return this
    return replace("0*$".toRegex(), "").replace("\\.$".toRegex(), "")
}

[ephemient]

IMO it would be better to define it on String instead of String?. it returns null iff the receiver is null, so instead of doing that, just push the safe call to the consumers, e.g. nullable?.trimTrailingZeros(). if the receiver is non-nullable, this will ensure the result is also non-nullable

[ephemient]

anyway, given that,

fun String.trimTrailingZeros(): String =
    if ('.' in this) trimEnd('0').trimEnd('.') else this

would be a straightforward translation without using regex

[KV]

Ahh nice thanks 🙂

[Matteo Mirk]

@ephemient very cool solution but I suspect it won’t always work. For example, this is what the OP wanted and it works:

"1.000".trimTrailingZeros() --> 1

but these cases don’t work as expected:

"1.1000".trimTrailingZeros() --> 1.1
"1.10200".trimTrailingZeros() --> 1.102

is this correct?

[ephemient]

that's what the original function returns too

[Matteo Mirk]

Oh I see maybe I got it wrong sorry…

[ephemient]

why wouldn't it be correct?

[Matteo Mirk]

never mind, I misunderstood the requirement when reading the code 😄

[Mark]

Or just replace("[.]?0*$".toRegex(), "") (although still need to check a period exists before calling this).

[Mark]

Note: the trimEnd() function will remove all trailing characters and so is a little different from the OP’s second regex which only replaces last period.

[ephemient]

if there are multiple . in a row, yeah. that's actually easy to resolve if it is an issue though,

trimEnd('0').removeSuffix(".")

[bjonnh]

if they are numbers you could do a .toDouble().toString() as in: https://pl.kotl.in/An1Dc6M3Q

[bjonnh]

of course it has to fit in Double etc etc