filterIndexed

Returns a char sequence containing only those characters from the original char sequence that match the given predicate.

inline fun CharSequence.filterIndexed(predicate: (index: Int, Char) -> Boolean): CharSequence(source)

val original = "kotlin"
val filtered = original.filterIndexed { index, c -> index % 2 == 0 }
println(filtered) // outputs: "koi"

Source