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A Simple Calculator in Visual Basic for Beginners



Written by:sowoolumide
Published by:SAJChurchey
Published on:2010-03-22 22:37:02
Topic:Visual Basic
Search OSI about Visual Basic.More articles by sowoolumide.
 viewed 38017 times send this article printer friendly

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This is a more optimized Visual Basic calculator. It contains neater code and lets you understand better on how you can code the same calculator. In short, neater code.

Requirements:

Visual Studio/ Visual basic express.
Understanding of the visual studio or visual basic environment.

1.Launch Visual Studio/ Visual Basic
2. Create a new project and name it whatever you want, e.g Calculator.
............................................................................................



Leave the form in the default name, which should be "form1" or rename it if you want in the properties pane.

Now drag buttons on the form to make it look like the diagram below.
The buttons can be resized to look how you want them to look. The text box was also resized.
For the text on the buttons, click the button you want to change its text value and go to the properties pane, you would see the text property there. you can change it there.



Now use the following names for the buttons on the forms.

BUTTONS
"1" - Button1
"2" - Button2
"3" - Button3
"4" - Button4
"5" - Button5
"6" - Button6
"7" - Button7
*"8" - Button8
*"9" - Button9
*"0" - Button10
*"+" - Button_Add
"" - Button_Multiply
*"-" - Button_Minus
*"=" - Button_Equal
*"C" - Button_Clear
*"/" - Button_Divide
*"." - Button_Point
Text box - Textbox1.text



Double click on the form and add the following code.

Public Class Form1
    ' We create this variables as globals so they can be accessed from any where in the program.

    ' this varible is for the mathematical symbol clicked. e.g +, - .
    Dim sign As Char
    ' This variable stores the first value entered by the user.
    Dim first As Double
    ' This variable stores the second value entered by the user.
    Dim second As Double
    ' This variable stores the answer of the calculation
    Dim ans As Double
    ' This variable stores a value 1 or 0 to tell if the calculation is complete or not.
    Dim stat As Integer

    '
    Sub confirm()
        stat = 1
        first = TextBox1.Text
    End Sub
    ' This subroutine checks the mathematical symbol that was clicked using a select case statement.
    ' This is more efficient then using several if statements.
    ' Then its performs the calculation based on the symbol chosen.
    ' It then sets the calculator status to 1 to show the calculation is complete(stat=1).
    ' It then displays your result in the textbox (TextBox1.Text = ans)
    Sub action()

        Select Case sign
            Case "+"
                ans = first + TextBox1.Text
            Case "-"
                ans = first - TextBox1.Text
            Case "*"
                ans = first * TextBox1.Text
            Case "/"
                ans = first / TextBox1.Text

            Case Else

        End Select
        stat = 1
        TextBox1.Text = ans
    End Sub

    Sub addnum(ByRef a As String)

        If TextBox1.Text = 0 Then
            TextBox1.Text = a
        Else
            TextBox1.Text = TextBox1.Text & a
        End If
        If stat = 1 Then
            TextBox1.Text = a
            stat = 0
        End If
    End Sub

    ' using addnum() in the button click event prevents having to write the same code for every button click.
    ' event. The parameter in the subroutine is the number that should be added to the text button on the button click.
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        addnum(1)
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        addnum(2)
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        addnum(3)
    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        addnum(4)
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        addnum(5)
    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        addnum(6)
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        addnum(7)
    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        addnum(8)
    End Sub

    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
        addnum(9)
    End Sub

    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        addnum(0)
    End Sub

    Private Sub Button_Add_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Add.Click
        sign = "+"
        confirm()
    End Sub

    Private Sub Button_Minus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Minus.Click
        sign = "-"
        confirm()
    End Sub

    Private Sub Button_Multiply_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Multiply.Click
        sign = "*"
     confirm()
    End Sub

    Private Sub Button_Divide_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Divide.Click
        sign = "/"
       confirm()
    End Sub

    Private Sub Button1_Clear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1_Clear.Click
        TextBox1.Text = 0
        stat = 0
        first = TextBox1.Text
    End Sub

    Private Sub Button_Equal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Equal.Click
        action()

    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    End Sub

    Private Sub Button_Point_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Point.Click
        addnum(".")
    End Sub
End Class

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Comments:
Anonymous
2010-12-07 06:52:48
how about in if else statement only???
pointblank
2011-04-20 18:59:18
thx for the code. http://www.dudijaya.com
Anonymous
2011-06-30 11:00:38
good
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