Simple Calculator in (VB) Visual Basic with Source Code

Submitted by Allaoui on Monday, December 28, 2020 - 16:48.

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This is a Sample calculator that I created in visual basic 2008, and this sample will be more useful for learners who are interested in VB 2008 and fortunately the VS 2019 can upgrade the source code perfectly. You can study it and modify it as more as you like.

How to Build a Simple Calculator

First, create an Interface for your calculator which has the following:

TextField
Buttons for the numbers
Buttons for the Operators
Button for the Result
Off, Clear, and Backspace Button

In my Case, this is the interface I used. Calculator Inter face

After that, set the variables for the operator, value 1, value 2, and other needed for operations.

Option Explicit On
 
Public Class Form1
    Dim Operand1 As Double
    Dim Operand2 As Double
    Dim [Operator] As String
 
    Dim hasDecimal As Boolean
    Dim tmpValue As Double
End Class

Then, for each number buttons. For script below, my textfield named as "txtInput" and "cmd1" for my number 1 button.

    Private Sub cmd1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmd1.Click
        txtInput.Text = txtInput.Text & sender.text
    End Sub

For the operation buttons except for the square root button, follow the script below and change the "[Operator]" value according to the operator you have set to the button.

Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdAdd.Click
        Operand1 = Val(txtInput.Text)
        txtInput.Text = ""
        txtInput.Focus()
        [Operator] = "+"
    End Sub

And for the equal/result button. Use the following code below.

 Private Sub Button23_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button23.Click
        Dim Result As Double
        Operand2 = Val(txtInput.Text)
 
        Select Case [Operator]
            Case "+"
                Result = Operand1 + Operand2
                txtInput.Text = Result.ToString()
            Case "-"
                Result = Operand1 - Operand2
                txtInput.Text = Result.ToString()
            Case "/"
                Result = Operand1 / Operand2
                txtInput.Text = Result.ToString()
            Case "*"
                Result = Operand1 * Operand2
                txtInput.Text = Result.ToString()
            Case "^"
                Result = Operand1 ^ Operand2
                txtInput.Text = Result.ToString()
            Case "%"
                Result = Operand1 * 1 / 100
                txtInput.Text = Result.ToString()
 
 
        End Select
 
        txtInput.Text = Result.ToString()
 
    End Sub

Next is we will create the function that calculates the square root of the value when the square root button will be clicked.

   Private Sub cmdSqrtRoot_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdSqrtRoot.Click
        'Make sure the input box has a value
        If txtInput.Text.Length <> 0 Then
            'Assign our variable the value in the input box
            tmpValue = CType(txtInput.Text, Double)
            'Perform the square root
            tmpValue = System.Math.Sqrt(tmpValue)
            'Display the results in the input box
            txtInput.Text = CType(tmpValue, String)
            'Clear the decimal flag
            hasDecimal = False
        End If
 
    End Sub

And lastly, creating a function for the button clear, backspace, and decimal.

'for the Decimal
 Private Sub cmdDecimal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdDecimal.Click
        If InStr(txtInput.Text, ".") > 0 Then
            Exit Sub
        Else
            txtInput.Text = txtInput.Text & "."
        End If
    End Sub
 
'Clear Function
 Private Sub CmdClearAll_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CmdClearAll.Click
        txtInput.Text = ""
 
End Sub
 
'Off Function
 Private Sub cmdOFF_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CmdOff.Click
 
        txtInput.Text = ""
 
 End Sub

That's it, you can now try to debug your simple calculator and test if the Source Code works perfectly as planned. In case it doesn't work the way it should be, you download the working source code below.

Happy Coding : )

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