[Kotlin][String] indexOf

지정된 startIndex 부터 시작하여 지정된 문자열이 처음 나타나는 이 문자 시퀀스 내의 인덱스를 반환합니다.

public fun CharSequence.indexOf(string: String, startIndex: Int = 0, ignoreCase: Boolean = false): Int {
    return if (ignoreCase || this !is String)
        indexOf(string, startIndex, length, ignoreCase)
    else
        nativeIndexOf(string, startIndex)
}


fun matchDetails(inputString: String, whatToFind: String, startIndex: Int = 0): String {
    val matchIndex = inputString.indexOf(whatToFind, startIndex)
    return "Searching for '$whatToFind' in '$inputString' starting at position $startIndex: " +
    if (matchIndex >= 0) "Found at $matchIndex" else "Not found"
}

val inputString = "Never ever give up"
val toFind = "ever"

println(matchDetails(inputString, toFind)) // Searching for 'ever' in 'Never ever give up' starting at position 0: Found at 1
println(matchDetails(inputString, toFind, 2)) // Searching for 'ever' in 'Never ever give up' starting at position 2: Found at 6
println(matchDetails(inputString, toFind, 10)) // Searching for 'ever' in 'Never ever give up' starting at position 10: Not found

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indexOf - Kotlin Programming Language