kotlin-stdlib/kotlin.text/indexOfFirst

indexOfFirst

inline fun CharSequence.indexOfFirst(predicate: (Char) -> Boolean): Int(source)

Returns index of the first character matching the given predicate, or -1 if the char sequence does not contain such character.

Since Kotlin

1.0

Samples

import kotlin.test.*

fun main() { 
   //sampleStart 
   val string = "Kotlin knowledge"

println(string.indexOfFirst { it == 'K' }) // 0
println(string.indexOfFirst { it == 'k' }) // 7
println(string.indexOfFirst { it == 'n' }) // 5
println(string.indexOfFirst { it == ' ' }) // 6
println(string.indexOfFirst { it == 'z' }) // -1

val emptyString = "";
println(emptyString.indexOfFirst { it == 'z' }) // -1 
   //sampleEnd
}
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