Does Kotlin have a standard way to format a number as an English ordinal?

Question

In Swift, I can do something like this:

let ordinalFormatter = NumberFormatter()
ordinalFormatter.numberStyle = .ordinal

print(ordinalFormatter.string(from: NSNumber(value: 3))) // 3rd

but I don't see any way to do this so easily in Kotlin. Is there such a way, or will I have to use 3rd-party libraries or write my own?

Well, it is usually hard to prove that something doesn't exist. :) But I'm almost sure there's no such function in stdlib or anything that can be immediately adapted for it. Moreover, stdlib doesn't contain anything locale-specific, and you should actually resort to some third-party software or implement your own solution. — hotkey, Jan 21 '17 at 00:01

hotkey · Accepted Answer · 2022-11-25T15:00:44.657

14

Well, it is usually hard to prove that something doesn't exist. But I have never come across any function in kotlin-stdlib that would do this or could be immediately adapted for this. Moreover, kotlin-stdlib doesn't seem to contain anything locale-specific (which number ordinals certainly are).

I guess you should actually resort to some third-party software or implement your own solution, which might be something as simple as this:

fun ordinalOf(i: Int) {
    val iAbs = i.absoluteValue // if you want negative ordinals, or just use i
    return "$i" + if (iAbs % 100 in 11..13) "th" else when (iAbs % 10) {
        1 -> "st"
        2 -> "nd"
        3 -> "rd"
        else -> "th"
    }
}

Also, solutions in Java: (here)

edited Nov 25 '22 at 15:00

answered Jan 21 '17 at 00:38

hotkey

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The `Int` class could also be extended, for example: `fun Int.asOrdinal() ...` – TakingItCasual Jun 10 '19 at 11:50
This doesn't work for negatives – Ky - Oct 28 '22 at 18:48
@Ky- Are negative ordinals a thing? I'm curious about your use case. – hotkey Oct 29 '22 at 19:03
1

@hotkey `"Find the $ordinal root of this number"` -> `Find the -4th root of this number` – Ky - Nov 01 '22 at 22:01
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@Ky, yeah, and I also found out about negative floor numbers (like, -2nd floor). – hotkey Nov 25 '22 at 14:42
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It seems that just using the `absoluteValue` to determine the suffix should work if you want negative ordinals. – hotkey Nov 25 '22 at 14:59

score 2 · Answer 2 · answered Oct 28 '22 at 06:59

2

Here's my take, a variant of @hotkey's solution:

    fun Int.ordinal() = "$this" + when {
        (this % 100 in 11..13) -> "th"
        (this % 10) == 1 -> "st"
        (this % 10) == 2 -> "nd"
        (this % 10) == 3 -> "rd"
        else -> "th"
    }

Invoke with e.g. 13.ordinal().

answered Oct 28 '22 at 06:59

neu242

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This doesn't work for negatives – Ky - Oct 28 '22 at 18:47

Does Kotlin have a standard way to format a number as an English ordinal?

2 Answers2