Calculation problem

[Andaleeb]

1.
Can I do calculations in text boxes? Suppose the text property of a textbox is "2*4+5" and I want the result in an integer type variable iResult so that iResult = 13. So whenever I call iResult it will give me the integer 13, not the string "2*4+5".

2.
Suppose, this is the code I have

for x = 1 to 10
y = text1.text
print x
next x

Now I will enter "2 * x + 5" in the textbox and the output would be 7,9,11...

[Thomas Halsvik]

I think you will have to make your own calculator. That last part there with X can be complicated. Anyway, I made this code for you to help you get started.

Sub Main()
    Dim Acc As Double
    Dim A(100) As Variant
    Dim i As Integer
    Dim c As Integer
    Dim Calculate As String
    Dim curUnit As String
    Dim pos As Long
    Calculate = "20*3+42/3"
    pos = 1
    i = 1
    'Gets all the components.
    While pos < Len(Calculate) + 1
        curUnit = getUnit(Calculate, pos)
        pos = pos + Len(curUnit)
        A(i) = curUnit
        i = i + 1
    Wend
    
    'The calculator part
    Acc = Val(A(1))
    For c = 2 To i - 1 Step 2
        Select Case A(c)
            Case "*": Acc = Acc * Val(A(c + 1))
            Case "-": Acc = Acc - Val(A(c + 1))
            Case "+": Acc = Acc + Val(A(c + 1))
            Case "/": Acc = Acc / Val(A(c + 1))
            Case Else: MsgBox "unknown"
        End Select
    Next c
    MsgBox Acc
End Sub

Function isNumber(number As String) As Boolean
    If Trim(Str(Val(number))) = number Then isNumber = True
End Function

Function getUnit(Calc As String, pos As Long) As String
    getUnit = Mid(Calc, pos, 1)
    If isNumber(getUnit) Then
        getUnit = getUnit & getNumber(Calc, pos + 1)
    End If
End Function

Function getNumber(Calc As String, pos As Long) As String
    getNumber = Mid(Calc, pos, 1)
    If isNumber(getNumber) Then
        getNumber = getNumber & getNumber(Calc, pos + 1)
    Else
        getNumber = ""
    End If
End Function

[ccoder]

If you feel that you could follow some C or pascal code and are interested, I have a small calculator program written in both Turbo Pascal and Turbo C. It inputs an equation and displays the result.

It is a very good example of parsing.

If interested, contact me offline.