Question

Objectives

To develop a recursive solution that reurns a tuple

To develop a program that manages bad input

Description

Write a program (sumAndCount.scala) that uses a recursive function that reads Int values from a user one at a time until the user types in the word "quit" (case insensitive!). Your function should return a tuple containing 2 Int values. The first should be the sum of all the Ints, and the second should be the number of Ints entered. Your main program should call this function, and print out the average (rounded) of the values that were entered. Note: You will also need to manage bad input! If the user types something in that isn't an Int or the word "quit", your program should print an error message and ask again! As always, pay close attention to the specific messages that your program must print.

Remember: You don't want any side effects with recursion, so you should not use any "global" variables in your program!

Sample Run 1

$ scala sumAndCount.scala

Enter an Int (type "quit" to quit):

>3

Enter an Int (type "quit" to quit):

>55

Enter an Int (type "quit" to quit):

>78

Enter an Int (type "quit" to quit):

>2

Enter an Int (type "quit" to quit):

>Quit

The average of your 4 numbers is 35

Sample Run 2

$ scala sumAndCount.scala

Enter an Int (type "quit" to quit):

>2

Enter an Int (type "quit" to quit):

>3

Enter an Int (type "quit" to quit):

>4.0

That is not an Int or "quit"!

Enter an Int (type "quit" to quit):

>4

Enter an Int (type "quit" to quit):

>5

Enter an Int (type "quit" to quit):

>quiT

The average of your 4 numbers is 4

Sample Run 3

$ scala sumAndCount.scala

Enter an Int (type "quit" to quit):

>3

Enter an Int (type "quit" to quit):

>78

Enter an Int (type "quit" to quit):

>2

Enter an Int (type "quit" to quit):

>245

Enter an Int (type "quit" to quit):

>quiit

That is not an Int or "quit"!

Enter an Int (type "quit" to quit):

>quit

The average of your 4 numbers is 82

Hints

Similar to the previous assignment, write 2 recursive functions. In this case, however, your function should check to make sure that the user enters eith an Int or the word "quit"

Consider (carefully!) what type of read you would need to use to accept either an Int or a String (in case the user enters "quit") Both are legal!

use the following prototype for your main recursive function:

def sumAndCount: (Int,Int) = { ... }

ACTIONS

Answer 1

I have implemented the sumAndCount(Int,Int) as per the given description.

Please find the following Code Screenshot, Output, and Code.

ANY CLARIFICATIONS REQUIRED LEAVE A COMMENT

1.CODE SCREENSHOT :

2.OUTPUT :

3.CODE :

object SumAndCountDemo{
   
   def sumAndCount (sum:Int,count:Int):List[Int]={
   //print the menu 
           print("Enter an Int (type \"quit\" to quit):\n>");
           //read the data
            var input = scala.io.StdIn.readLine()
                //if the input is quit then return 
                if(input.toLowerCase()=="quit"){
                //create the output list to return
                        var nums: List[Int] = List()
                         //append the term to the list
                   nums = nums:+(count);
                        nums = nums:+(sum);
                        //return the list 
                        return nums;                    
                }
                else if(scala.util.Try(input.toInt).isSuccess){
                //if the user enter a valid integer then call the sumAndCount with updated counts
                        var t=input.toInt;
                        sumAndCount(sum+t,count+1);
                        
                }else{
                //otherwise print error message
                print("That is not an Int or \"quit\"!\n");
                                sumAndCount(sum,count);
                }                
   } 
   def main(args: Array[String]):Unit={
      var nums: List[Int] =sumAndCount(0,0);
          print("The average of your "+nums(0)+" number is "+(nums(1).toFloat/nums(0)).ceil.toInt);
        }
}