Platform and version requirements: JVM (1.0), JS (1.0), Native (1.0)

inline fun <R> CharSequence.foldIndexed(
    initial: R, 
    operation: (index: Int, acc: R, Char) -> R
): R

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each character with its index in the original char sequence.

Parameters

operation - function that takes the index of a character, current accumulator value and the character itself, and calculates the next accumulator value.