how to get the result

hi,
i add a textbox into a form and input 2+2 in the textbox.

then i msgbox textbox..value ,2+2 is showed .

how can i get 4 instead of 2+2

thank you

regards

 

You mean that u have entered 2+2 on same text box?, then u need to concat the textbox1.text value for identifying the operator and add the values on either side of the operator and then display in msgbox.

Other wise, better method would be, using two text box and create a add button, whose event will add the two text box value and display in a msgbox.

 

Thanks for your advice.

but as a matter of fact, i wand to input more complicated expression. not
just 2+2

i have no idea about it.

thank you again

the textbox1.text value for identifying the operator and add the values on
either side of the operator and then display in msgbox.

button, whose event will add the two text box value and display in a msgbox.

 

You need make a function to convert the algebraic expression into a vb
operation
This is a simple example:

Private Function SimpleCalc(StrOp As String) As Double
Dim Operator(3) As String
Dim Op1 As Double
Dim Op2 As Double
Dim pos As Integer
Dim i As Integer
Operator(0) = "+"
Operator(1) = "-"
Operator(2) = "/"
Operator(3) = "*"

If StrOp = "" Then
SimpleCalc = 0
Else
'search for operator
For i = LBound(Operator) To UBound(Operator)
pos = InStr(1, StrOp, Operator(i))
If pos > 0 Then
Op1 = Val(StrOp)
Op2 = Val(Right$(StrOp, Len(StrOp) - pos))
Exit For
End If
Next i
Select Case i
Case Is = 0
SimpleCalc = Op1 + Op2
Case Is = 1
SimpleCalc = Op1 - Op2

Case Is = 2
If Op2 = 0 Then
MsgBox "Invalid operand"
SimpleCalc = 0
Else
SimpleCalc = Op1 / Op2
End If

Case Is = 3
SimpleCalc = Op1 * Op2

Case Else
MsgBox "Unknown operator"
SimpleCalc = 0
End Select
End If

End Function

 

thank you

this is a good idea,
it looks like that there isnot a easy way to solve the problem.

thanks

 

This can be quite complex but you will want to do most of your work in the
KeyPress event of the TextBox using a Select Case statement.

You will need to handle the display of numbers vs. operators and updating
the value shown. Don't forget about handling invalid characters as well.

Joe
--

 

Thanks for your advice.

could you tell something more concretely

thank you

 

Youngman,
Unfortunately, writing your own calculator routine, especially one that
allows more complicated functions than (+-*/), is not a simple task. I
think Joe was trying to say this by listing some of the speed bumps you will
have to make your code handle.

It would be nice if the Windows calculator would let you reference it and
send keystrokes or strings to be evaluated, but I don't know if it will. I
couldn't find it in the References list, so AFAIK you can't do this. Maybe
there's some shareware around that lets you do this...??

I think the quickest way to get to a robust calculator routine would be to
send strings to a Microsoft Excel object. Set a cell's formula equal to the
string (adding an "=" in front if necessary) and then read the cell's value.
If it's "#VALUE" or "#-anything" you have an error in the formula --
otherwise it's your calculator answer. You can find code snippets for
getting or creating an Excel object, and manipulating a cell by searching
the NG's.

If you want it to act like a calculator and have it know when to update the
value (depending on order of operators, parentheses, etc) then you need code
to track the current level of parenthesis, current list of operations to be
done (I think the real programmers would call this a stack and would have
code at their fingertips to manipulate it, but I don't). Otherwise just let
the user build a string up and whenever he hits Enter it gets sent through
Excel.

This is my best idea at the moment. Hope this helps,

James

 

What you need is the railroad shunting algorithm.
http://www.csse.monash.edu.au/~lloyd/tildeAlgDS/Stack/

A google search shows many many hits on this topic. The above is one that I
found easy to follow.

I believe that Frank O. has posted a working VB class module in the group
before...or maybe it was just posted on the site...I don't remember. Maybe
he'll post it again if we all ask nicely

 

thanks to you all

it looks like complicadted ,i have to think out another idea.
thanks

 

Maybe you could achieve something using the Eval method.

Regards

Wayne Ivory
IT Analyst Programmer
Wespine Industries Pty Ltd