maxOfOrNull

Returns the largest value among all values produced by selector function applied to each character in the char sequence or null if the char sequence is empty.

inline fun CharSequence.maxOfOrNull(selector: (Char) -> Double): Double?(source)

fun main() {
    val text = "kotlin 123"

    // Find the largest character code as a Double
    val maxCode = text.maxOfOrNull { it.code.toDouble() }
    println("Maximum character code: $maxCode")   // prints 114.0 for 't'

    // Example with an empty sequence
    val empty = "".maxOfOrNull { it.code.toDouble() }
    println("Empty string result: $empty")         // prints null
}

Source