Kotlin: Phone Bill calculator-CodePudding

I'm new at kotlin. Now I'm trying to code a Phone Bill Calculator, when I have to charge user 0.25 for every minute they were over their plan, and 15% tax on subtotal. I can't find the 15% tax.

import java.util.*

    fun main(args: Array<String>) {
        var numberOfCalls: Int
        val phoneBill: Float
        val thetax: Float = 15f
        val scan = Scanner(System.`in`)
        print("Enter the Total Minutes of Calls Made this Month: ")
        numberOfCalls = scan.nextInt()
        if (numberOfCalls <= 60) phoneBill = 10f else {
            numberOfCalls = numberOfCalls - 60
            phoneBill = ((10   (numberOfCalls * 0.25 )).toFloat()   (thetax/100))
        }
        println("\nTelephone Bill this Month = $phoneBill")
    }

CodePudding user response：

Instead of using this formula bill = total total * tax you was using this bill = total taxPercentage which is wrong, you can calculate it like that and have theTaxAmount separately ( you can use it somewhere ):

fun main(args: Array<String>) {
    var numberOfCalls: Int
    val phoneBill: Float
    val theTaxPercentage: Float = 0.15f
    val scan = Scanner(System.`in`)
    print("Enter the Total Minutes of Calls Made this Month: ")
    numberOfCalls = scan.nextInt()
    if (numberOfCalls <= 60) phoneBill = 10f else {
        numberOfCalls -= 60
        val phoneBillWithoutTax = (10   (numberOfCalls * 0.25 )).toFloat()
        val theTaxAmount = phoneBillWithoutTax * theTaxPercentage
        phoneBill = phoneBillWithoutTax   theTaxAmount
    }
    println("\nTelephone Bill this Month = $phoneBill")
}

CodePudding user response：

Your algebra error is that you didn't multiply the tax by anything. You just added it like it was a flat rate of 15 cents. A tax by percentage is multiplied by the total amount. And an algebra tip: it's less math (and less code) to multiply something by 115% (1.15) than it is to figure out what 15% would be and add it to the original value.

I find it is easier (and has clearer code) to solve a problem by doing minimal number of steps at a time instead of setting up all your variables at the start and then modifying them. Create/initialize what you need only immediately before you will use it. Basically, if you can write your logic out of vals and no vars, usually this will be a cleaner solution.

fun main(args: Array<String>) {
    print("Enter the Total Minutes of Calls Made this Month: ")
    val scan = Scanner(System.`in`)
    val numberOfMinutes = scan.nextInt()

    var excessMinutes = numberOfMinutes - 60
    if (excessMinutes < 0) {
        excessMinutes = 0
    }
    val bill = 10   excessMinutes * 0.25
    val taxedBill = bill * 1.15

    println("\nTelephone Bill this Month = $taxedBill")
}

The four lines of code for excessMinutes can be shortened as below, but I wrote it out verbosely since you are just learning how the basic logic works, and if you're doing this for a class, the teacher might not expect you to be using helper functions like that yet.

val excessMinutes = max(0, numberOfMinutes - 60)