Stuck on how to request a user to input two numbers for "num1" and "num2" and do arithmetic.

[Dan Good]

Hey guys, new to programming, and my teacher wants us to declare two variables : num1 and num2, and have the user input values, then run it through 2*num1 - num2.

Here is what I have so far, and I am lost and frustrated:

package hellowworld;

import java.util.Scanner;

public class definevariables 
{		
		static Scanner console = new Scanner(System.in);
		
		public static void main(String[] args)
		{
			
		int num1;
		int num2;
		
		num1 = ();
		System.out.println("num1 = " + num1);
		System.out.print("Enter an integer!: ");
		
		num2 = ();
		System.out.println("num2 = " + num2);
		System.out.print("Enter an integer!: ");
			
		num1 = 2 * num1 - num2;
		
		System.out.println("The value of two times num1 minus num2 is equal to " + "num1 = " + num1);
		}
}

[Prasanna Raman]

Hello Dan,

Kindly use code tags when you post code here. It looks much better

Let's look at this line

num1 = ();

You need to receive an input from the user and assign it to num1, correct? Look at how you can do it using Scanner in this link.

You should be able to figure it out. Let us know how you go.

[Dan Good]

Thanks you for showing me this, I guess my greatest issue is that I have no idea how to use the code provided. As in, where should I put it in my program?

[Prasanna Raman]

Look at how the example takes input from the user.

Scanner sc = new Scanner(System.in);
int i = sc.nextInt();

Look at what the 2nd line does here. Your num1 is 'i' in this example.

[Dan Good]

I think this worked when I ran it in Eclipse, but I can't get the program to use the inputed numbers in the equation "2*num1 - num2".

package hellowworld;

import java.util.Scanner;

public class definevariables 
{		
		static Scanner console = new Scanner(System.in);
		
		public static void main(String[] args)
		{
			
		int num1;
		int num2;
		int answer;
		
		System.out.print("Enter value for num1: ");
		num1 = console.nextInt();
		System.out.println();
		
		System.out.print("Enter value for num2: ");
		num2 = console.nextInt();
		System.out.println();
		
		System.out.print("2 times num1 minus num2 equals: ");
		answer = console.nextInt(2 * num1 - num2);
		System.out.println();
		
		}
}

[Prasanna Raman]

Think about what you're doing in this line of code.

answer = console.nextInt(2 * num1 - num2); 

The nextInt() method is used to receive an integer input from the user. Do you need an input from the user to compute your answer?

[Dan Good]

You're right, I don't need an input. I need the program to take the inputed values of num1 and num2 and calculate them. How should I go about doing that?

[Louis Denning]

Dan Good wrote:You're right, I don't need an input. I need the program to take the inputed values of num1 and num2 and calculate them. How should I go about doing that?

Simply do System.out.println(2 * num1 - num2); or make answer equal (2 * num1 - num2) first and then System.out.println(); it out

[Dan Good]

Thank you so much! It worked!

Final:

package hellowworld;

import java.util.Scanner;

public class definevariables 
{		
		static Scanner console = new Scanner(System.in);
		
		public static void main(String[] args)
		{
			
		int num1;
		int num2;
		int answer;
		
		System.out.print("Enter value for num1: ");
		num1 = console.nextInt();
		System.out.println();
		
		System.out.print("Enter value for num2: ");
		num2 = console.nextInt();
		System.out.println();
		
		System.out.println(2 * num1 - num2);
		
		
		}
}

[Louis Denning]

What are you being taught at the moment? I'm curious to what different programming courses start with.

[Dan Good]

Inputs, Outputs, decrements, increments, class string, at Fairfield University. We use the book Java Programming: From Problem Analysis to Program Design. The book is difficult to follow if you know nothing about coding...

[Louis Denning]

Ah, I see. If the book gets too clunky at times or if you ever have any questions, we're here to help. \ ^ o ^ /

[Dan Good]

This forum is great, thank you guys so much!

[Louis Denning]

Well, I'm kinda new to the forums, too
Nice place, I must admit.

[Dan Good]

cheers mate!

[Amruta nikam]

Dan Good wrote:Inputs, Outputs, decrements, increments, class string, at Fairfield University. We use the book Java Programming: From Problem Analysis to Program Design. The book is difficult to follow if you know nothing about coding...

well for beginners Head first java is the best book so far