A modern programming language that makes developers happier.

kotlinlang

is the a function to anonymise a String? i.e. to only keep the last n digits and replace the rest with `*`?

```
fun anonymise(s: String, n: Int): String {
        val replaceLength = kotlin.math.min(s.length, n)
        val replaceChars = String(CharArray(replaceLength, {'*'} ))
        return "$replaceChars${s.substring(replaceLength)}"
    }
    
    @Test
    fun `anonymise`() {
        anonymise("blah", 3).shouldBe("***h")
        anonymise("blah", 4).shouldBe("****")
        anonymise("blah", 5).shouldBe("****")
    }```

maybe someone can suggest something neater

```
fun String.anonymise(numberOfCharactersToHide: Int = this.length - 1) =
        replaceRange(0,
                kotlin.math.min(this.length -1, numberOfCharactersToHide),
                "*")

```

it's untested, by default will replace all the characters but the last one

I hadn't come across `replaceRange`, totally the right tool for the job!
kotlinlang is such a great slack channel

Ah, except that replaces the entire range with a single asterisk

```
fun Char.times(n: Int) = String(CharArray(n, {this} ))

    fun String.anonymise(numberOfCharactersToHide: Int = this.length - 1): String {
        val resolvedCharacterToHide = kotlin.math.min(this.length, numberOfCharactersToHide)

        return replaceRange(
            0,
            resolvedCharacterToHide,
            '*'.times(resolvedCharacterToHide)
        )
    }

    @Test
    fun `anonymise`() {
        val s = "blah"
        s.anonymise(3).shouldBe("***h")
        s.anonymise(4).shouldBe("****")
        s.anonymise(5).shouldBe("****")
    }```

Something like this should work
<https://gist.github.com/antonis/cb95f56a85c703bc015f6d1c02348493>