Hi T-Bear,
Before I provide anything that might resemble a real answer, do you want to know how to do it or do you just need to do it?
The reason I ask is simply because the answer depends on where you're going with it. If it's part of a larger problem and you just need a solution then the answer will be very different to if you want to know how to go about doing it.
Edit:- Another question to go with this... do you want to access variables from within your program so they can be used in the expression you are evaluating?
Regards
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