OpenEuphoria

Re: parsing expressions

• Posted by David Cuny <dcuny at LANSET.COM> Jun 23, 1999
• 498 views

Geert-Jan Gerritsen wrote:

> I'm looking for a way to evaluate mathematical expressions using
> Euphoria. The application I'm developing asks the user to input a
> math function, which has to be evaluated along the way. You know,
> something like the good old VAL statement in Basic.

There are a number of routines posted at the RDS site under:

   The Archive | Library Routines | Euphoria Expression Evaluator
   The Archive | Library Routines | Expression Evaluator
   The Archive | Simple Demos | Expression Evaluator

The last library is my own, and was written for someone else to provide the
sort of functionality you are asking for. I *think* that someone else had
complained that the association was off if you didn't use parentheses, i.e.:

   a * b * c * d

is evaluated as:

   ( ( a * b ) * c ) * d

instead of:

   ( a * ( b * ( c * d )

I always use parens when I'm in doubt. If you plan on using mine, let me
know if this is a problem, and I'll see if I can resolve it.

-- David Cuny