Kotlin Essential Training

Chapter 4 - Section 8

	fun main(args: Array<String>) {
		try {
			print("Number 1: ")
			val string1: String? = readLine()
			val number1 = string1!!.toDouble()

			print("Number 2: ")
			val string2 = readLine()
			val number2 = string2!!.toDouble()

			print("Select an operation (+ - / *): ")
			val operation = readLine()

			val result: Double? =
					when (operation) {
						"+" -> addValues(number1, number2)
						"-" -> subtractValues(number1, number2)
						"*" -> multiplyValues(number1, number2)
						"/" -> divideValues(number1, number2)
						else -> throw Exception("Unknown operation")
					}
			println("The answer is $result")
		} catch (e: NumberFormatException) {
			println("${e.message} is not a number")
		} catch (e: Exception) {
			println(e.message)
		}
	}

	fun multiplyValues(number1: Double, number2: Double) = number1 * number2
	fun divideValues(number1: Double, number2: Double) = number1 / number2
	fun subtractValues(number1: Double, number2: Double) = number1 - number2
	fun addValues(number1: Double, number2: Double) = number1 + number2