Let's try to develop a C++ Reverse Polish Notation (RPN) calculator!

Create a base class called Operand

Derive a class called Number from Operand

- Maintain a double variable in class Number

- If you like, you can make the variable public for simplicity

Derive a class called Operator from Operand

- Derive a class called Add from Operator

- Derive a class called Subtract from Operator

- Derive a class called Multiply from Operator

- Derive a class called Divide from Operator

Almost all of the above classes are going to be empty

- Only class Number will have a true constructor and member variables

- If you wish you can put all of these classes into a file called Operands.h

Develop some C++ code that does the following:

- Create a queue of Operand pointers

- Use push_back operations to build the stack just like you would using RPN

- Develop a function called Calculate which takes in a stack and returns the double result

The Calculate() function must do the following:

- For each element of the queue starting at the front:

+ If the operand is a Number, add it to a stack

+ If the operand is an Operator, pop two values off the stack and use that operator to do the correct math, then put the new value back on the stack

= You'll need to use dynamic_cast to make this work

- When things complete, the stack should hold the final result. Return it.

Example:

std::queue a;

a.push_back(new Number(1));

a.push_back(new Number(2));

a.push_back(new Add());

std::cout << Calculate(a); // Prints 3