Check whether a String contains a character in Kotlin

This article explores different ways to check whether a String contains a character in Kotlin.

1. Using `indexOf()` function

The indexOf() function returns the index of the first occurrence of a char within the string. If the character does not exist, it returns -1. This value can be used to check if the given character appears in the string or not, as shown below:

fun main() {

val s = "Kotlin"

val c = 'o'

val isExist = s.indexOf(c) != -1

println(isExist) // true

}

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2. Using `contains()` function

Alternatively, we can use the contains() function to check if a char is present in the string or not.

fun main() {

val s = "Kotlin"

val c = 'o'

val isExist = s.contains(c)

println(isExist) // true

}

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We can make the comparison case-insensitive, as follows:

fun main() {

val s = "Kotlin"

val c = 'k'

val isExist = s.contains(c, ignoreCase = true)

println(isExist) // true

}

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3. Using `in` operator

The most idiomatic way to check if a string contains a character is using the in operator. This is equivalent to calling the contains() function, but offers shorter and more readable syntax.

fun main() {

val s = "Kotlin"

val c = 'o'

val isExist = c in s

println(isExist) // true

}

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That’s all about checking whether a String contains a character in Kotlin.

Check whether a String contains a character in Kotlin

1. Using indexOf() function

2. Using contains() function

3. Using in operator

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1. Using `indexOf()` function

2. Using `contains()` function

3. Using `in` operator