This is the final version, but still check back for any updates.

A different assignment was briefly listed as hw 6, That assignment is now hw 7.

Required reading: Savitch text Chapters 1-8. This exercise should be done using only the material from Chapters 1 through 8.

Due dates: Check the Announcements.

Note you can do this and take an interview without turning in the assignment, as long as it is before the turnin deadline.

You may work in teams of two students, but once you form a team, you cannot change the team for this assignment. You may work alone if you prefer.

Programming: Write a program that uses the class Calculator in Display 8.11 to create a more powerful calculator. This calculator will allow you to save one result in memory and call the result back.

Commands are:
-e for end
-c for clear, sets result to 0
-m for save in memory, sets memory equal to result
-r for recall memory, displays the value of memory, but does not change result

You should define a derived class of the class Calculator that has one more instance variable for the memory, a new main, a redefinition of the method handleUnknownOpException, a main method that runs the improved calculator, and anything else new or redefined that you need. What a sample dialog should look like is shown in what follows. Your program need not produce an identical dialog, but it should be similar and just as nice or nicer.

Calculator on:
result = 0.0
+4
result + 4.0 = 4.0
updated result = 4.0
/2
result / 2.0 = 2.0
updated result = 2.0
m result saved in memory
c
result = 0.0
+99
result + 99.0 = 99.0
updated result = 99.0
/3
result / 3.0 = 33.0
updated result = 33.0
r
memory recall
memory value = 2.0
result = 33.0
+2
result + 2.0 = 35.0
updated result = 35.0
e
End of Program

Hints: You do not need to redefine the methods evaluate or handleDivideByZeroException. They are inherited from the class calculator and work fine as is. You probably do want to redefine the methods handleUnknownOpException and doCalculation.

Last Update: Feb 05, 2003 (by Nakul Verma)