Project Number 4 and Calculator

Code

    /// Name: Brendan Baird
    /// Period: 6
    /// Program Name: Calculator
    /// File Name: Calculator.java
    /// Date Finished: 2/16/2016
    
    import java.util.Scanner;

    public class Calculator
    {
        public static void main(String[] args)
        {
            Scanner keyboard = new Scanner(System.in);
        
            double a, b, c;
            String op;
    
            do
            {
                System.out.print("> ");
                a  = keyboard.nextDouble();
                op = keyboard.next();
                b  = keyboard.nextDouble();
    
                if ( op.equals("+") )
                    c = a + b;
                else if ( op.equals("-") )
                    c = a - b;
                else if ( op.equals("*") )
                    c = a * b;
                else if ( op.equals("/") )
                    c = a / b;
                else if ( op.equals("^") ){
                    c = 1;
                    for (int i = 0; i < b; i++){
                        c = c * a;
                    }
                }
                else if ( op.equals("%") )
                    c = a % b;
                else
                {
                    System.out.println("Undefined operator: '" + op + "'.");
                    c = 0;
                }
    
                if ( a != 0 )
                    System.out.println(c);
    
            } while ( a != 0 );
            System.out.println("Goodbye");
        }
    }
    

Picture of the output