5 replies to this topic

[Cruel Hand]

I made this simple 4 function calculator but I get a run time error saying the variable "answer" isn't initialized, which it clearly is...can someone help? thanks :D

import java.util.Scanner;


public class calc {

	public static void main(String args[]) {

		Scanner number = new Scanner(System.in);

		double function, fnum, snum, answer;

		System.out.print("Enter 1 for mult, 2 for div, 3 for add, 4 for sub: ");

		

		function = number.nextDouble();

		

		System.out.println("Enter first number:");

		fnum = number.nextDouble();

		System.out.println("Enter second number:");

		snum = number.nextDouble();

		

		if(function == 1){

			answer = fnum * snum;

		}

		if(function == 2){

			answer = fnum / snum;

		}

		if(function == 3){

			answer = fnum + snum;

		}

		if(function == 4){

			answer = fnum - snum;

		}

		System.out.println("Answer: " + answer);

	}


}

[lethalwire]

If all 4 "if's" evaluate to false, then "answer" will never be initialized. The compiler is trying to catch this.

[Cruel Hand]

ohh ok, that's what I thought. So if I made an else statement that restarted the program then would it work?

thanks for the quick reply btw :)

[lethalwire]

Yup, that would work, which is probably the best choice.
Or you can initialize the "answer" variable before the if tests. Like setting it equal to -1, or Integer.MAX_VALUE, or whatever.

[Cruel Hand]

how could I tell the compiler to restart the program if function doesn't equal 1, 2, 3, or 4? I looked it up and people said to call the main method but I don't know how to do that.

[lethalwire]

You could use a while loop that runs until function = 1, 2, 3, or 4. After function = 1, 2, 3, or 4 end the while loop.