Scientific Calculator

In previous post, I have discussed about a new project , i.e. creating scientific calculator. Now, we shall add the number buttons, a cancel button and a dot button. The number buttons are created as an array of buttons, and each button will be identified with its index, corresponding to its caption.

I will also replace the display panel with a label so that the users won't be able to erase the number. They can only clear the number by clicking the cancel button. The alignment property of the label is set to right justified, so that the digit entered will start from the right position, similar to the conventional calculator.

The value of pi is now obtained by using the Atn function (Arc Tangent). We know that Tan(pi/4)=1, so Atn(1)=pi/4, therefore pi=Atn(1)*4. By using this function, we will obtain a more accurate value of pi.

In this project, we shall also limit the numbers to be less than 30 digit. If any user enters a number with more than 30 digits, an error message "data overflow" will be shown.

The Interface:


The code :

Dim Num_of_digit As Integer
Private Sub buttonNum_Click(Index As Integer)
If Num_of_digit > 0 And Num_of_digit <> "0" Then
panel.Caption = panel.Caption + Right$(Str$(Index), 1)
ElseIf panel.Caption = "0" Then
panel.Caption = Str$(Index)
End If

ElseIf Num_of_digit >= 30 Then
panel.Caption = "Data Overflow"

Else

panel.Caption = Right$(Str$(Index), 1)

End If

Num_of_digit = Num_of_digit + 1



End Sub

Private Sub Clear_Click()

panel.Caption = "0"
Num_of_digit = 0

End Sub

Private Sub Command1_Click(Index As Integer)
Dim x As Double
Dim pi As Double
pi = Atn(1) * 4
Select Case Index

Case 0
x = Val(panel.Caption)
panel.Caption = Round((Sin(x * pi / 180)), 4)
Num_of_digit = 0

Case 1
x = Val(panel.Caption)
panel.Caption = Round((Cos(x * pi / 180)), 4)
Num_of_digit = 0
Case 2
x = Val(panel.Caption)
panel.Caption = Round((Tan(x * pi / 180)), 4)
Num_of_digit = 0

End Select

End Sub