kotlin-stdlib/kotlin.text/digitToIntOrNull

digitToIntOrNull

fun Char.digitToIntOrNull(): Int?(source)

Returns the numeric value of the decimal digit that this Char represents, or null if this Char is not a valid decimal digit.

A Char is considered to represent a decimal digit if isDigit is true for the Char. In this case, the Unicode decimal digit value of the character is returned.

Since Kotlin

1.5

Samples

import java.util.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   println('5'.digitToIntOrNull()) // 5
println('3'.digitToIntOrNull(radix = 8)) // 3
println('A'.digitToIntOrNull(radix = 16)) // 10
println('K'.digitToIntOrNull(radix = 36)) // 20

// radix argument should be in 2..36
// '0'.digitToIntOrNull(radix = 1) // will fail
// '1'.digitToIntOrNull(radix = 100) // will fail
// only 0 and 1 digits are valid for binary numbers
println('5'.digitToIntOrNull(radix = 2)) // null
// radix = 10 is used by default
println('A'.digitToIntOrNull()) // null
// symbol '+' is not a digit in any radix
println('+'.digitToIntOrNull()) // null
// Only Latin letters are valid for digits greater than 9.
println('β'.digitToIntOrNull(radix = 36)) // null 
   //sampleEnd
}
fun Char.digitToIntOrNull(radix: Int): Int?(source)

Returns the numeric value of the digit that this Char represents in the specified radix, or null if this Char is not a valid digit in the specified radix. Throws an exception if the radix is not in the range 2..36.

A Char is considered to represent a digit in the specified radix if at least one of the following is true:

  • isDigit is true for the Char and the Unicode decimal digit value of the character is less than the specified radix. In this case the decimal digit value is returned.

  • The Char is one of the uppercase Latin letters 'A' through 'Z' and its code is less than radix + 'A'.code - 10. In this case, this.code - 'A'.code + 10 is returned.

  • The Char is one of the lowercase Latin letters 'a' through 'z' and its code is less than radix + 'a'.code - 10. In this case, this.code - 'a'.code + 10 is returned.

  • The Char is one of the fullwidth Latin capital letters '\uFF21' through '\uFF3A' and its code is less than radix + 0xFF21 - 10. In this case, this.code - 0xFF21 + 10 is returned.

  • The Char is one of the fullwidth Latin small letters '\uFF41' through '\uFF5A' and its code is less than radix + 0xFF41 - 10. In this case, this.code - 0xFF41 + 10 is returned.

Since Kotlin

1.5

Samples

import java.util.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   println('5'.digitToIntOrNull()) // 5
println('3'.digitToIntOrNull(radix = 8)) // 3
println('A'.digitToIntOrNull(radix = 16)) // 10
println('K'.digitToIntOrNull(radix = 36)) // 20

// radix argument should be in 2..36
// '0'.digitToIntOrNull(radix = 1) // will fail
// '1'.digitToIntOrNull(radix = 100) // will fail
// only 0 and 1 digits are valid for binary numbers
println('5'.digitToIntOrNull(radix = 2)) // null
// radix = 10 is used by default
println('A'.digitToIntOrNull()) // null
// symbol '+' is not a digit in any radix
println('+'.digitToIntOrNull()) // null
// Only Latin letters are valid for digits greater than 9.
println('β'.digitToIntOrNull(radix = 36)) // null 
   //sampleEnd
}