Adding 3 User Input Numbers together

Question

I am doing an exercise from a site where I am trying to add 3 numbers the user inputs only using three variables. The code they let you start off with is:

Scanner reader = new Scanner(System.in);
int sum = 0;
int read;

// WRITE YOUR PROGRAM HERE
// USE ONLY THE VARIABLES sum, reader AND read!

System.out.println("Sum: " + sum);

I was thinking of using a for loop but I keep getting stuck because I can only use three variables. reader is already being used by Scanner. sum is going to be changing values, and read is going to be a temporary value.

I would have used

System.out.println("Enter a number: ");
int read = Integer.parseInt(reader.nextLine());

But that would have only held 1 number. Any help I've been stuck on this for a while.

Jake H. · Accepted Answer · 2016-02-06 02:28:02Z

2

This should satisfy the requirement:

for(read = 3; read > 0; read--) {
    System.out.println("Enter a number: ");
    sum += Integer.parseInt(reader.nextLine());
}

edited Feb 6, 2016 at 2:28

answered Feb 6, 2016 at 2:25

Jake H.

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4 Comments

Elliott Frisch Over a year ago

Or just sum = reader.nextInt() + reader.nextInt() + reader.nextInt()

Nabz Over a year ago

Thanks jheim do you mind telling me how you came up with the solution.

Jake H. Over a year ago

Grab my latest edit. I was missing a semicolon, and changed read >= 0 to read > 0.

Jake H. Over a year ago

Well, I tried to incorporate a use of all the variables you had listed. So I decided I would use read as my counter in the for loop. Since we needed to add three values, I set read to 3. The rest of the logic you had already, just incorporated the += operator to add the values to sum. Make sense?

Nick Gammon · Accepted Answer · 2016-02-06 03:01:44Z

0

Would this do it? It obviously doesn't scale to hundreds of numbers:

int read;
System.out.println("Enter a number: ");
read = Integer.parseInt(reader.nextLine());
sum += read;

System.out.println("Enter a second number: ");
read = Integer.parseInt(reader.nextLine());
sum += read;

System.out.println("Enter a third number: ");
read = Integer.parseInt(reader.nextLine());
sum += read;

No this is what i had as well, but it didn't work

Full version - this works for me.

import java.util.Scanner;

public class HelloWorld {
    public static void main(String[] args) {
    Scanner reader = new Scanner(System.in);
    int sum = 0;
    int read;

    System.out.println("Enter a number: ");
    read = Integer.parseInt(reader.nextLine());
    sum += read;

    System.out.println("Enter a second number: ");
    read = Integer.parseInt(reader.nextLine());
    sum += read;

    System.out.println("Enter a third number: ");
    read = Integer.parseInt(reader.nextLine());
    sum += read;

    System.out.println("Sum: " + sum);

    }
}

Output:

Enter a number: 
22
Enter a second number: 
10
Enter a third number: 
50
Sum: 82

Of course, a simpler version based on what jheimbouch did would be better:

import java.util.Scanner;

public class HelloWorld 
  {
    public static void main(String[] args) 
    {
    Scanner reader = new Scanner(System.in);
    int sum = 0;

    for(int read = 1; read <= 3; read++) 
      {
      System.out.println("Enter number " + read + ": ");
      sum += Integer.parseInt(reader.nextLine());
      }

    System.out.println("Sum: " + sum);

    }
 }

edited Feb 6, 2016 at 3:01

answered Feb 6, 2016 at 2:26

Nick Gammon

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3 Comments

Nick Gammon Over a year ago

Doesn't compile? Doesn't add the numbers?

Nabz Over a year ago

Hmm this is weird I had the same thing as your original one but it would always say read already has a value

Nick Gammon Over a year ago

Did you maybe have int read = Integer.parseInt(reader.nextLine()); which would mean you had defined read?

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