Kotlin Training Program

Parse digit

We have digitToIntOrNull() built-in function to parse digit from a Char :

 fun main() {
    println('0'.digitToIntOrNull()) // Prints 0
}
 

Recall that character code of digits lies in the range 48..57. So, to convert a digit character to Int, we can simple subtract ‘0’.code or 48 from its code :

 fun Char.digitToIntOrNull(): Int? {
    return if (this in '0'..'9')
        this.code - '0'.code
    else
        null
}