RE: Calculator and Operator Precedence

["Steven Deller" <deller@smsail.com>]

Interestingly, I just cobbled together Ada code to parse arbitrary Ada
expressions consisting of just operators, parentheses, and literals (I'm
probably going to make it handle type conversions as well).

It uses two stacks (one for operands, one for operators), and recursion
(on parentheses).  Since each stack only needs a maximum of 5 entries
(because of Ada's left to right evaluation for equal precedence
operators) they could have been done with simple arrays (though I used a
stack package abstraction).

You don't need trees.  

I thought about using a grammar-based parse (Matthew H's solution), but
it has some problems with recognizing where you are in the grammar.

Unary operators are the biggest complication.

About 50 lines of code.  If you can prove you're not doing a student
exercise, I'd be glad to send you the sources.

Regards,
Steve