At 2:58 PM +0000 1/31/05, Hugh Neill wrote:
I am an absolute beginner, except that I have worked the tutorial and
attempted to read various books.
I am trying to design a program part of which will evaluate a function
supplied by the user.
Wow, you're jumping right into the deep end. This is a very hard
problem for a beginner. Val() does not do this for you, you have to
work at it. Let me sketch out some approaches:
1. You can use an RBScript object. You'd need to feed it some source
code that assigns the initial value of x, and then Prints the result
of the expression the user entered. You'd get the answer in the
Print event of the RBScript, which you could then display as you like.
2. You could write your own expression evaluator, probably using a
simple recursive-descent parser. If this sounds like Greek to you,
then you probably shouldn't attempt it until you get more experience
under your belt. However, if you want to give it a try, I can send
some sample code.
3. I believe that Bob Delaney has a plug-in that will evaluate
expressions. Search the NUG archives. Bob has many math-related
plugins, all very high quality and free.
Best,
- Joe
--
REAL World 2005 - The REALbasic User Conference
March 23-25, 2005, Austin, Texas
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