Need Expression Evaluator for comparison statements

[MindXFlayer]

I am looking for a class/API call that can take:
6 > 5 OR 7 > 5 AND (A = B)

and return either True or False.

I have found plenty of math expression evaluators and tried the EbExecuteLine (but it requires vba6.dll which is not always registered on a system) but have yet to find what I need.

Any pointers would be appreciated!!

 

[Scoty]

What about Cbool() does that not help?

Just a thought
Scoty : "Learn from others' mistakes. You could not live long enough to make them all yourself."
-- Hyman George Rickover (1900-86),

 

[strongm]

I think you may find that this is a problem with operator precedence. Presumably, no matter what the values assigned to A and B, you are getting the answer True - which makes you feel that VB's built-in expression evaluator is somehow wrong. But precedence says that AND is evaluated before OR, which means that firstly 7 > 5 and (A = B) gets evaluated (which will result in True or False depending on A and B), and then 6 > 7 OR True/False gets evaluated, which will always give you True. So you need to use parenthesis. The following will, I suspect, allow VB to evaluate the expression as you expect it to:

(6 > 5 OR 7 > 5) AND (A = B)

 

[MindXFlayer]

Scoty, thanks for the reply. Unfortunately, Cbool can not take a string like "6 > 5". It takes "6" > "5", i.e. the comparison operator (>) can not be part of the string.

Strongm, thanks for the reply. The problem is that I need to send this as a string. So I am given the string "6 > 5" and would like to know if the string is true/false without parsing it. Something like eval does in Javascript. Mind Flayer
---
MindXFlayer@hotmail.com

 

[strongm]

Ah! Well, in that case you want to look at the MS Script Control. Just add a reference to it in your project, and then try out:
[tt]
Dim WSC As ScriptControl

Set WSC = New ScriptControl

WSC.Language = "vbscript"
MsgBox WSC.Eval("6 > 5&quot
Set WSC = Nothing
[/tt]
Or, if you want to do it without making a reference:
[tt]
Dim WSC As Object

Set WSC = CreateObject("MSScriptControl.ScriptControl&quot 'New ScriptControl

WSC.Language = "vbscript"
MsgBox WSC.Eval("6 > 5&quot
Set WSC = Nothing

 

[MichaelRed]

Hmmmmmmm,

Something strange this way comes.

The Expression works "O.K." - if "A" and "B" are VARIABLES

as in:

A = 4
B = 5
? Eval("6 > 5 AND 7 > 5&quot AND (A = B)


It is ALSO "O.K." if "A" and "B" are (properly?) delimited as literals,

as in:

? Eval("6 > 5 AND 7 > 5 AND 'A' = 'B'&quot
0

So, despite much ado over the process, I think you need to be CAREFUL about what you ask for -after all- YOU JUST MIGHT get it (or even already have it?) and just not 'appreciate' it?


MichaelRed
m.red@att.net

There is never time to do it right but there is always time to do it over