Number Base Converter

Main.kt

package converter

import java.math.BigDecimal
import kotlin.math.pow

tailrec fun convertFromDecimal(rest: Long, base: Int, result: List<String>): List<String> {
    return if (rest < base) {
        result + rest.toString(base)
    } else {
        val remainder = rest % base
        val quotient = rest / base
        convertFromDecimal(quotient, base, result + remainder.toString(base))
    }
}

fun convertFromDecimal(number: Long, base: Int): String {
    return convertFromDecimal(number, base, emptyList())
        .reversed()
        .joinToString("") { it }
}

fun convertFractionalFromDecimal(fractional: BigDecimal, base: Int): String {
    val result = mutableListOf<String>()
    var remaining  = fractional
    var precision = 1
    while (precision <= 5 && remaining.compareTo(BigDecimal.ZERO) != 0) {
        remaining = remaining.multiply(base.toBigDecimal())
        val integerPart = remaining.toInt()
        if (integerPart > 0) {
            result.add(integerPart.toString(base))
            remaining = remaining.subtract(integerPart.toBigDecimal())
        } else {
            result.add("0")
        }
        precision++
    }
    return result.joinToString("") { it.toString() }
}

fun convertToDecimal(number: String, base: Int): Long {
    return number.toLowerCase().reversed().mapIndexed {
            i, c -> (Integer.valueOf(c.toString(), base) * base.toDouble().pow(i)).toLong()
    }.sum()
}

fun convertFractionalToDecimal(factional: String, base: Int): BigDecimal {
    return factional.toLowerCase().mapIndexed { i, c ->
        val number = Integer.valueOf(c.toString(), base)
        if (number == 0) {
            number.toBigDecimal()
        } else {
            (number * base.toDouble().pow(-(i+1))).toBigDecimal()
        }
    }.reduceRight(BigDecimal::add)
}

fun convert(number: String, source: Int, target: Int): String {
    return try {
        if (number.contains('.')) {
            val (integer, fractional) = number.split(".")
            val decimalInteger = convertToDecimal(integer, source)
            val convertedInteger = convertFromDecimal(decimalInteger, target)
            val decimalFractional = convertFractionalToDecimal(fractional, source)
            val convertedFractional = convertFractionalFromDecimal(decimalFractional, target)
            "$convertedInteger.$convertedFractional"
        } else {
            val decimal = convertToDecimal(number, source)
            convertFromDecimal(decimal, target)
        }
    } catch (e: Throwable) {
        "error when trying to convert $number from base $source to base $target"
    }
}

fun convert(source: Int, target: Int) {
    while (true) {
        print("Enter number in base ${source} to convert to base $target (To go back type /back) ")
        val input = readLine()!!
        if (input == "/back") {
            break
        }
        if (source == target) {
            if (input.contains(".")) {
                val (integer, fractional) = input.split(".")
                println("Conversion result: $integer.${fractional.substring(0, 5)}")
            } else {
                println("Conversion result: $input")
            }
        } else {
            val result = convert(input, source, target)
            println("Conversion result: $result")
        }
        println()
    }
}

fun main() {
    while (true) {
        print("Enter two numbers in format: {source base} {target base} (To quit type /exit) ")
        val command = readLine()!!
        if (command == "/exit") {
            break
        }
        val (source, target) = command.split(" ").map { it.toInt() }
        convert(source, target)

    }
}

Great program! But it has some problem:

Enter two numbers in format: {source base} {target base} (To quit type /exit) 2 5
Enter number in base 2 to convert to base 5 (To go back type /back) 1011000100.00000
Conversion result: 10313.
The conversion result is missing zeroes after the decimal point.

Thanks. It was only a fun experiment. Don't take this code too seriously :)

No problem! I just tried it, and found the problem. Actually it is a good program! Yannick Grenzinger ***@***.***> ezt írta (időpont: 2023. jan. 16., Hét 19:06):

…

***@***.**** commented on this gist. ------------------------------ Thanks. It was only a fun experiment. Don't take this code too seriously :) — Reply to this email directly, view it on GitHub <https://gist.github.com/054605355c0e91b7d114afad1745b6ed#gistcomment-4438778> or unsubscribe <https://github.com/notifications/unsubscribe-auth/ALUJJXN47TU55YFHGH3FFALWSWE2ZBFKMF2HI4TJMJ2XIZLTSKBKK5TBNR2WLJDHNFZXJJDOMFWWLK3UNBZGKYLEL52HS4DFQKSXMYLMOVS2I5DSOVS2I3TBNVS3W5DIOJSWCZC7OBQXE5DJMNUXAYLOORPWCY3UNF3GS5DZVRZXKYTKMVRXIX3UPFYGLK2HNFZXIQ3PNVWWK3TUUZ2G64DJMNZZDAVEOR4XAZNEM5UXG5FFOZQWY5LFVEYTAOBSHEYTKMBZU52HE2LHM5SXFJTDOJSWC5DF> . You are receiving this email because you commented on the thread. Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub> .