Assignment #73 and Baby Calculator

Code

    ///Name: Tim Gibson
    ///Period: 6
    ///Project Name: Baby Calculator
    ///File Name: BabyCalculator.java
    ///Date Finished: 10/26/15
        
    import java.util.Scanner;
    
    public class BabyCalculator
    {
    	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("+") && a != 0 )
                {
                    c = a + b;
                    System.out.println(c);
                }
    			else if ( op.equals("*") && a != 0)
                {    
                    c = a * b;
                    System.out.println(c);
                }
                else if ( op.equals("-") && a != 0)
                {
                    c = a - b;
                    System.out.println(c);
                }
                else if ( op.equals("/") && a != 0)
                {    
                    c = a / b;
                    System.out.println(c);
                }
                else if ( a == 0 )
                    System.out.println( "Bye, now." );
                else
    			{
    				System.out.println("Undefined operator: '" + op + "'.");
    				c = 0;
    			}
    
    			
    
    		} while ( a != 0 );
    	}
    }
        

Picture of the output