Reverse Polish Notation (RPN, or postfix) calculator

• Arguments written before operators
  • 3 + 4 * 7 would be 3 4 7 * +
• Calculation is easy:
• Each argument read is pushed onto a stack
• If a (binary) operator is read:
  • Pop top two values
  • Perform appropriate operation
  • Push result back onto stack
• Add 2 commands:
  1. p - print the top of the stack
  2. q - quit the program