KotlinHow-ToBeginner · 3 min read

How to Use toCharArray in Kotlin: Simple Guide

In Kotlin, you can use the toCharArray() function to convert a String into an array of characters (CharArray). This function returns a new array containing each character of the string in order.

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Syntax

The toCharArray() function is called on a String object and returns a CharArray containing all characters of the string.

String.toCharArray(): Converts the string into a character array.

kotlin

val chars: CharArray = "Hello".toCharArray()

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Example

This example shows how to convert a string to a character array and print each character on a new line.

kotlin

fun main() {
    val text = "Kotlin"
    val charArray = text.toCharArray()
    for (char in charArray) {
        println(char)
    }
}

Output

K o t l i n

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Common Pitfalls

One common mistake is trying to use toCharArray() on a null string, which causes a NullPointerException. Always ensure the string is not null before calling this function.

Another mistake is confusing toCharArray() with toCharArray(startIndex, endIndex) which does not exist in Kotlin; slicing must be done separately.

kotlin

fun main() {
    val nullableText: String? = null
    // Wrong: nullableText?.toCharArray() ?: CharArray(0) is safe, but nullableText.toCharArray() throws error

    // Correct way:
    val safeCharArray = nullableText?.toCharArray() ?: CharArray(0)
    println(safeCharArray.size) // prints 0
}

Output

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Quick Reference

Function	Description
toCharArray()	Converts entire string to CharArray
nullableString?.toCharArray() ?: CharArray(0)	Safe call to handle null strings
string.toCharArray().size	Gets number of characters in string

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Key Takeaways

Use toCharArray() to convert a Kotlin string into a character array.

Always check for null before calling toCharArray() to avoid errors.

The returned CharArray contains characters in the same order as the string.

There is no built-in substring version of toCharArray(); slice the string first if needed.

Iterate over the CharArray to access individual characters easily.