Question

In Java:

Write a program that prompts the user to enter a positive number until the user input a negative number. In the end, the program outputs the sum of all the positive numbers.

You should use do-while loop (not while, not for). You cannot use break or if statement in the lab.

Hint: if the program adds the last negative number to your sum, you can subtract the last number from the sum after the loop.

Answer 1

import java.util.*;
public class Main
{
        public static void main(String[] args) {
            
            Scanner sc = new Scanner(System.in);
            //initialize variables
            int num,sum = 0,ans;
            
            //loop runs continuously untill user entered negative number
            do{
                //prompts user to enter number and store it in num variable
                System.out.print("Enter number: ");
                num= sc.nextInt();
                
                //add each number to find sum of all number
                sum = sum + num;
                
            }
            //when user entered negative number loop terminates
            while( num > 0);
            
            //in sum negative number is also added.
            //To find sum of all positive number subtract the
            //negative number from sum and store result in ans
            ans = sum - num;
            
            //prints the result
            System.out.println("Sum:" + ans);
        }
}

Output: