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How to convert a number to its word representation with commas in Kotlin

How to convert a number to its word representation with commas in Kotlin.

Here is a step-by-step tutorial on how to convert a number to its word representation with commas in Kotlin.

Step 1: Create a function to convert a number to its word representation.

fun convertNumberToWords(number: Long): String {
    // TODO: Implement the logic to convert the number to words
}

Step 2: Check if the number is zero.​

if (number == 0L) {
    return "zero"
}

Step 3: Define arrays for the word representations of numbers.​

val units = arrayOf("one", "two", "three", "four", "five", "six", "seven", "eight", "nine")
val tens = arrayOf("ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety")
val teens = arrayOf("eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen")
val thousands = arrayOf("", "thousand", "million", "billion", "trillion")

Step 4: Create a helper function to convert a three-digit number to words.

fun convertThreeDigitNumber(number: Int): String {
    val hundred = number / 100
    val remainder = number % 100
    var words = ""

    if (hundred > 0) {
        words += "${units[hundred - 1]} hundred"
    }

    if (remainder in 1..9) {
        words += " ${units[remainder - 1]}"
    } else if (remainder in 11..19) {
        words += " ${teens[remainder - 11]}"
    } else if (remainder in 20..99) {
        val ten = remainder / 10
        val unit = remainder % 10
        words += " ${tens[ten - 1]}"

        if (unit > 0) {
            words += "-${units[unit - 1]}"
        }
    }

    return words.trim()
}

Step 5: Implement the logic to convert the number to words.​

fun convertNumberToWords(number: Long): String {
    if (number == 0L) {
        return "zero"
    }

    val parts = mutableListOf<String>()
    var remainingNumber = number

    while (remainingNumber > 0) {
        val threeDigitNumber = (remainingNumber % 1000).toInt()
        val words = convertThreeDigitNumber(threeDigitNumber)

        if (words.isNotEmpty()) {
            val thousandIndex = (parts.size - 1) / 3
            val thousandWord = thousands[thousandIndex]
            parts.add("$words $thousandWord")
        }

        remainingNumber /= 1000
    }

    return parts.reversed().joinToString(", ")
}

Step 6: Test the function with sample inputs.​

fun main() {
    println(convertNumberToWords(0)) // zero
    println(convertNumberToWords(123)) // one hundred twenty-three
    println(convertNumberToWords(1000)) // one thousand
    println(convertNumberToWords(123456789)) // one hundred twenty-three million four hundred fifty-six thousand seven hundred eighty-nine
}

That's it! You now have a function that can convert a number to its word representation with commas in Kotlin.