Project #1

Create an interactive program to evaluate Reverse Polish (RPN) numeric expressions. The expression should be a single string containing operands and operators.

Examples

The order (left to right) of operators and operands in Infix and RPN expressions.

Evaluation Algorithm

loop:

1. ask the user to enter a RPN expression
   
   It should be a string containing operators and operands
   separated by commas and/or blanks. (e.g. "1,2 + 4 /")


2. replace all commas with spaces in the RPN string


3. split RPN string into separate tokens
   (spaces are token separators)


4. process the tokens one at a time from left to right
   
   
   create a stack for each token: if the token is an operand: push token onto the stack continue if the token is an operator: There should be at least two operands on the stack. If not there is an error. a = pop from the stack b = pop from the stack push (b op a) onto the stack continue display error message break results = pop from the stack display results After obtaining the result, the stack should be empty. If not there is an error.
   
   
   Note: This algorithm accepts a more limited (stricter)
   syntax. I.e. operand - operator - operand (infix: a*b)

You can find another description of the algorithm HERE .