Simple calculation

Getting Started
#1

Is there a way to solve simple calculations in the form (with calculation rules):
2 + (5-3) * 2

A string with natural numbers and basic operators.

#2

Sure: CDbl will give you the value of a result as a double; CStr will change an integer or a double to a string.

So, something like this in a pushbutton’s Action event will show you.

MsgBox(CStr(CDbl(“2 + (5-3) * 2”)))

#3

Perfect! Thank you!

#4

That solution won’t work, and the MsgBox will give you the answer “2” for that particular string (it’s returning the first number it finds). You’ll need to write a routine to run through the calculation.

#5

Your best bet would probably be to use a XojoScript object.

  1. Add a XojoScript object to your project (e.g. XojoScript1).
  2. Add the following to the XojoScript1.Print event:
MsgBox msg // msg is the answer
  1. Add the following code to an action event of a button
  Dim expression As String = "2 + (5-3) * 2"
  
  XojoScript1.Source = "Print(Str(" + expression + "))"
  XojoScript1.Run

Just set the expression variable equal to the expression that you need to evaluate. The msg parameter in the XojoScript1.Print event can be converted to a double with:

MyAnswer = Val(msg)
#6

Here is a link to a nice solution

http://www.xdevzone.com/2008/01/creating-an-eval-function-using-rbscript/

#7

Yes, I just found it out. I will have a look at the scripting. Thanks…

(hmm. can’t remove the “this pos answered my question” mark…)

#8

Go up to your original post and point at the “answer” there. You will see the “X” that will let you remove it.

#9

An example of this is included with Xojo:

Examples/Advanced/XojoScript/Evaluator

#10