elementAt

Returns a character at the given index or throws an IndexOutOfBoundsException if the index is out of bounds of this char sequence.

expect fun CharSequence.elementAt(index: Int): Char(source)

val text = "Hello, Kotlin!"
val index = 7

val character = text.elementAt(index)
println("Character at index $index is '$character'")  // prints: Character at index 7 is 'K'

Source