Hello, I've a piece of function which does the fol...

# getting-started

[otakusenpai]

Hello, I've a piece of function which does the following:

inline fun letterInRange(char: Char): Boolean = char.compareTo('a')  || char.compareTo('b') ||
                                                   char.compareTo('c') || char.compareTo('d') ||
                                                   char.compareTo('e') || char.compareTo('f') ||
                                                   char.compareTo('g') || char.compareTo('h')

Is there a way to shorten the function a bit more? I mean there are too many cases(and yes its giving an error too....)

[spand]

Put them in a set and use contains() ?

[Rafal]

there is a CharRange in kotlin

[Rafal]

https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.ranges/-char-range/index.html

[Jake]

This should work, I haven’t tried it though.

inline fun letterInRange(char: Char) = when(char) {
    in 'a'..'h' -> true
    else -> false
}

[Rafal]

fun main(args : Array<String>) {
	
    val charRange = CharRange('a', 'g')
    print(charRange.contains('b')) //true
    print(charRange.contains('z')) //false
}

[Jake]

Yea use @Rafal’s answer.

[Tsvetozar Bonev]

('a'..'b').contains('a')

[Dias]

'a' in 'a'..'h'

[hudsonb]

^ inline fun letterInRange(char: Char): Boolean = char in 'a'..'h'

[otakusenpai]

wow thnx guys a lot ❤️

[otakusenpai]

i think char in 'a'..'h' is more concise...can you tell how it works? i can see tht it makes a CharArray of 'a' to 'h'

[otakusenpai]

nvm i see now

[hudsonb]

Can actually be a bit more concise by removing the explicit return type: inline fun letterInRange(char: Char) = char in 'a'..'h'

[hudsonb]

The error in your original version was due to compareTo returning an Int, which you can't do boolean logic on (||)

[Alan Evans]

P.S. No good reason to use inline here

[Alan Evans]

as for how it works if you put this in IDE (IntelliJ):

fun letterInRange(char: Char): Boolean = char.compareTo('a') >= 0 && char.compareTo('h') <= 0

[Alan Evans]

It will suggest:

fun letterInRange(char: Char): Boolean = char >= 'a' && char <= 'h'

[Alan Evans]

And then it will suggest a range check:

fun letterInRange(char: Char): Boolean = char in 'a'..'h'

[Alan Evans]

so that kind of explains how it works as all these pieces of code are equivalent.
Note that Range checks can be used on any Comparable

[Alan Evans]

Also note that it actually does not "create" a range instance or a CharArray for this. i.e. it is not allocating an object to do this check, it's just a shorthand.

[otakusenpai]

Hmm thnx for the insight