all

Common

JVM

Native

1.0

inline fun CharSequence.all(
    predicate: (Char) -> Boolean
): Boolean

(source)

Returns true if all characters match the given predicate.

Note that if the char sequence contains no characters, the function returns true because there are no characters in it that do not match the predicate. See a more detailed explanation of this logic concept in "Vacuous truth" article.

import kotlin.test.*

fun main(args: Array<String>) {
//sampleStart
val isEven: (Int) -> Boolean = { it % 2 == 0 }
val zeroToTen = 0..10
println("zeroToTen.all { isEven(it) } is ${zeroToTen.all { isEven(it) }}") // false
println("zeroToTen.all(isEven) is ${zeroToTen.all(isEven)}") // false

val evens = zeroToTen.map { it * 2 }
println("evens.all { isEven(it) } is ${evens.all { isEven(it) }}") // true

val emptyList = emptyList<Int>()
println("emptyList.all { false } is ${emptyList.all { false }}") // true
//sampleEnd
}