Kotlin String - toIntOrNull() Function

The Kotlin string toIntOrNull() function is used to convert or parse the string as an Int number and returns the result. If the string is not converted or not a valid representation of a number then it will return null.

Syntax

Following is the syntax of the Kotlin string toIntOrNull() function −

fun String.toIntOrNull(): Int?
fun String.toIntOrNull(radix: Int): Int?

Parameters

This function accepts a radix parameter, which represents the base of the number system to use to parse the string.

Return value

This function returns an Int if the string is a valid representation of the number. Otherwise; null.

Example 1: Convert a string into Int

Following is the basic example of converting a string to an int using the toIntOrNull() function −

fun main() {
   val number_str = "102510"
   val int_num = number_str.toIntOrNull()
   println(int_num)
}

Output

Following is the output −

102510

Example 2: Convert Binary String into Decimal

In this example, we use the toIntOrNull() function with a radix parameter to convert a binary string to a decimal integer −

fun main() {
   val binaryString = "1101"
   // Binary to Decimal
   val binaryNumber = binaryString.toIntOrNull(2)
   println("decimal number:" + binaryNumber)
}

Output

Following is the output −

decimal number:13

Example 3: Convert HexaDecimal String into Decimal

In this example, we use the toIntOrNull() function with a radix parameter to convert a hexadecimal string to a decimal integer −

fun main() {
   val hexString = "1A3F"
   // convert hexadecimal to decimal
   val hexNumber = hexString.toIntOrNull(16)
   println("Decimal Number: " + hexNumber)
}

Output

Following is the output −

Decimal Number: 6719