Develop a RPN rational number expression evaluator (REEval).

The learning objectives are:

• improved procedural programming skills
• improved confidence in designing and implementing applications involving ADTs
• experience implementing and using simple data structures (Stacks)
• understanding of the Reverse Polish Notation (RPN)
• further experience with incremental development

The REEval (Rational Expression Evaluator) C application supports evaluation of reverse polish notation (RPN) expressions containing fractions (rational numbers). It supports the four basic operations.  

The evaluator reads a line containing a reverse polish notation expression to be evaluated, and outputs the result.

- Operands are input as positive fractions, like 2/3.  

  When the denominator value is 1, operands are input as integers giving the numerator value, e.g. 4.

- Operators may be +, -, *, :, =, s, or q (s to output the stack, q to quit the program).