vb.NET Code

Imports System.Console
Imports System.Math
Public Class SampleCalculator
    Dim Num1 As Double
    Dim Num2 As Double
    Dim Total As Double
    Dim Operation As String
    Dim MPlus As String
    Dim Input As Boolean
    Dim Point As Boolean
    Dim ModOp As Boolean
    Private Sub BeforeLoad(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Me.KeyPreview = True
    End Sub
    Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn1.Text
        Else
            txtDisplay.Text = btn1.Text
            Input = True
        End If
    End Sub
    Private Sub btn2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn2.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn2.Text
        Else
            txtDisplay.Text = btn2.Text
            Input = True
        End If
    End Sub
    Private Sub btn3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn3.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn3.Text
        Else
            txtDisplay.Text = btn3.Text
            Input = True
        End If
    End Sub
    Private Sub btn4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn4.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn4.Text
        Else
            txtDisplay.Text = btn4.Text
            Input = True
        End If
    End Sub
    Private Sub btn5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn5.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn5.Text
        Else
            txtDisplay.Text = btn5.Text
            Input = True
        End If
    End Sub
    Private Sub btn6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn6.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn6.Text
        Else
            txtDisplay.Text = btn6.Text
            Input = True
        End If
    End Sub
    Private Sub btn7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn7.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn7.Text
        Else
            txtDisplay.Text = btn7.Text
            Input = True
        End If
    End Sub
    Private Sub btn8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn8.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn8.Text
        Else
            txtDisplay.Text = btn8.Text
            Input = True
        End If
    End Sub
    Private Sub btn9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn9.Click
        If (Input AndAlso txtDisplay.Text <> "0") Or Point Then
            txtDisplay.Text += btn9.Text
        Else
            txtDisplay.Text = btn9.Text
            Input = True
        End If
    End Sub
    Private Sub btn0_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn0.Click
        If Input Then
            If txtDisplay.Text.Length >= 1 AndAlso txtDisplay.Text <> "0" Then
                txtDisplay.Text += btn0.Text
            ElseIf Point Then
                txtDisplay.Text += btn0.Text
            End If
        End If
    End Sub
    Private Sub btnC_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnC.Click
        Num1 = 0
        Num2 = 0
        Operation = String.Empty
        txtDisplay.Text = ""
        Point = False
    End Sub
    Private Sub btnCE_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCE.Click
        Num2 = 0
        txtDisplay.Text = ""
        Point = False
    End Sub
    Private Sub btnMPlus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMPlus.Click
        MPlus = True
        MPlus = txtDisplay.Text
    End Sub
    Private Sub btnMR_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnMR.Click
        txtDisplay.Text = MPlus
    End Sub
    Private Sub btnMMinus_Click(sender As System.Object, e As System.EventArgs) Handles btnMMinus.Click
        MPlus = ""
    End Sub
    Private Sub Round(sender As System.Object, e As System.EventArgs) Handles btnRnd.Click
        '##########################
        '# Round
        '##########################
        'Rounds to nearest integer.
        Total = txtDisplay.Text
        txtDisplay.Text = Math.Round(Total)
    End Sub
    Private Sub btnInt_Click(sender As System.Object, e As System.EventArgs) Handles btnInt.Click
        '##########################
        '# Positive-Negative Integer
        '##########################
        txtDisplay.Text = -1 * txtDisplay.Text
    End Sub
    Private Sub DecimalValue(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDecimal.Click
        If Not Point Then
            If txtDisplay.Text.Length < 1 Then
                txtDisplay.Text = "0."
            Else
                txtDisplay.Text += "."
            End If
        End If
        Input = True
        Point = True
    End Sub
    Private Sub Addition(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSum.Click
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Add"
            Point = False
        End If
    End Sub
    Private Sub Subtract(sender As System.Object, e As System.EventArgs) Handles btnMinus.Click
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Subtract"
            Point = False
        End If
    End Sub
    Private Sub Multiply(sender As System.Object, e As System.EventArgs) Handles btnMultiply.Click
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Multiply"
            Point = False
        End If
    End Sub
    Private Sub Divide(sender As System.Object, e As System.EventArgs) Handles btnDivide.Click
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Divide"
            Point = False
        End If
    End Sub
    Private Sub Exponent(sender As System.Object, e As System.EventArgs) Handles btnExp.Click
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Exponent"
            Point = False
        End If
    End Sub
    Private Sub Modulous(sender As System.Object, e As System.EventArgs) Handles btnMod.Click
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            ModOp = True
            Point = False
        End If
    End Sub
    Private Sub btnFraction_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFraction.Click
        '##########################
        '# Fraction Calculator
        '##########################
        Num1 = txtDisplay.Text
        txtDisplay.Text = Str(Val(1) / Val(Num1)) & "  or  1 /" & Str(Val(Num1))
    End Sub
    Private Sub Percent(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPercent.Click
        '##########################
        '# Percent
        '##########################
        'Percentage calculation, example: 500 * 10% = 50
        Num2 = CType(txtDisplay.Text, Double)
        txtDisplay.Text = Val(Num1 * (Num2 / 100))
    End Sub
    Private Sub Lotto649(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLotto.Click
        '##########################
        '# Lotto649
        '##########################
        'Lotto 6/49 Button.
        Randomize()
        Dim Value1 As Integer = CInt(Int((49 * Rnd()) + 1))
        Dim Value2 As Integer = CInt(Int((49 * Rnd()) + 1))
        Dim Value3 As Integer = CInt(Int((49 * Rnd()) + 1))
        Dim Value4 As Integer = CInt(Int((49 * Rnd()) + 1))
        Dim Value5 As Integer = CInt(Int((49 * Rnd()) + 1))
        Dim Value6 As Integer = CInt(Int((49 * Rnd()) + 1))
        txtDisplay.Text = Value1 & "  " & Value2 & "  " & Value3 & "  " & Value4 & "  " & Value5 & "  " & Value6
    End Sub
    Private Sub InterestCalculations(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnIntCalc.Click
        '##########################
        '# Interest
        '##########################
        'Interest Calculator.
        Dim Money As Double
        Dim Percent As Decimal
        Dim Months As Double
        Money = txtIntVal.Text
        Percent = Val(txtIntPercent.Text / 100)
        Months = txtIntTime.Text
        txtDisplay.Text = "$" & Str(Val(Money * (1 + Percent * Months)))
    End Sub
    Private Sub CtoF(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFarenheit.Click
        '##########################
        '# CtoF
        '##########################
        'Celsius to farenheit conversion.
        Dim Celsius As Single
        Celsius = InputBox("Enter celsius value.", "Temperature Wizard: Celsius to Farenheit")
        txtDisplay.Text = Val(9 / 5 * Celsius + 32) & " °F"
    End Sub
    Private Sub FtoC(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCelsius.Click
        '##########################
        '# FtoC
        '##########################
        'Farenheit to celsius conversion.
        Dim Farenheit As Single
        Farenheit = InputBox("Enter farenehit value.", "Temperature Wizard: Farenheit to Celsius")
        txtDisplay.Text = Val(5 / 9 * (Farenheit - 32)) & " °C"
    End Sub
    Private Sub Taxes(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTaxes.Click
        '##########################
        '# Taxes
        '##########################
        'Tax calculator
        Dim Response As Decimal
        Response = InputBox("Enter tax percentage.", "Calculator Wizard Tax Master")
        txtDisplay.Text = "$" & Str(Val(txtDisplay.Text) * Val(Response / 10))
    End Sub
    Private Sub SquareRoot(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSquareRoot.Click
        '##########################
        '# SquareRoot
        '##########################
        'Square root function
        If txtDisplay.Text < "0" Then
            MsgBox("The root of a negative number is undefined!", 0, "WARNING")
        ElseIf txtDisplay.Text.Length <> 0 Then
            Operation = CType(txtDisplay.Text, Double)
            Operation = System.Math.Sqrt(Operation)
            txtDisplay.Text = CType(Operation, String)
            Point = False
        End If
    End Sub
    Private Sub Squared(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSquare.Click
        '##########################
        '# Squared
        '##########################
        'Multiplies number by itself.
        Num1 = txtDisplay.Text
        txtDisplay.Text = Val(Num1 ^ 2)
    End Sub
    Private Sub Master(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEqual.Click
        '##########################
        '# Equals Button
        '##########################
        If ModOp = True Then
            Num2 = Val(txtDisplay.Text)
            txtDisplay.Text = Num1 Mod Num2
        ElseIf txtDisplay.Text.Length <> 0 Then
            CalculateTotals()
            Operation = String.Empty
            Point = False
        End If
    End Sub
    Function CalculateTotals()
        '##########################
        '# Calculation Function
        '##########################
        Num2 = CType(txtDisplay.Text, Double)
        Select Case Operation
            Case "Add"
                Num1 += Num2
            Case "Subtract"
                Num1 -= Num2
            Case "Multiply"
                Num1 *= Num2
            Case "Divide"
                If Num2 = 0 Then
                    MsgBox("You CANNOT divide by 0.", MsgBoxStyle.Critical, "Error")
                End If
                Num1 /= Num2
            Case "Exponent"
                Num1 ^= Num2
        End Select
        txtDisplay.Text = CType(Num1, String)
        Point = False
    End Function
    Private Sub Interest(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnInterest.Click
        For x = 240 To 400 Step 0.075
            Me.Height = x
        Next
    End Sub
    Private Sub btnIntClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnIntClose.Click
        For x = 400 To 240 Step -0.075
            Me.Height = x
        Next
    End Sub
    Private Sub Keystrokes(sender As Object, e As KeyEventArgs) Handles Me.KeyDown
        '##########################
        '# Handles Keystrokes
        '##########################
        Select Case e.KeyCode
            Case Keys.NumPad0
                handleNumPadKeyPress(btn0)
            Case Keys.NumPad1
                handleNumPadKeyPress(btn1)
            Case Keys.NumPad2
                handleNumPadKeyPress(btn2)
            Case Keys.NumPad3
                handleNumPadKeyPress(btn3)
            Case Keys.NumPad4
                handleNumPadKeyPress(btn4)
            Case Keys.NumPad5
                handleNumPadKeyPress(btn5)
            Case Keys.NumPad6
                handleNumPadKeyPress(btn6)
            Case Keys.NumPad7
                handleNumPadKeyPress(btn7)
            Case Keys.NumPad8
                handleNumPadKeyPress(btn8)
            Case Keys.NumPad9
                handleNumPadKeyPress(btn9)
            Case Keys.Back
                handleNumPadKeyPress(btnCE)
            Case Keys.Subtract
                SubtractPress(btnMinus)
            Case Keys.Add
                AddPress(btnSum)
            Case Keys.Multiply
                MultiplyPress(btnMultiply)
            Case Keys.Divide
                DividePress(btnDivide)
            Case Keys.Enter
                EnterPress(btnEqual)
        End Select
    End Sub
    Private Sub handleNumPadKeyPress(btn As Button)
        '##########################
        '# Number Pad Keypress
        '##########################
        If (Input AndAlso txtDisplay.Text.Length <> 0) Or Point Then
            txtDisplay.Text += btn.Text
        Else
            txtDisplay.Text = btn.Text
            Input = True
        End If
    End Sub
    Private Sub SubtractPress(btn As Button)
        '##########################
        '# Subtract Button
        '##########################
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Subtract"
            Point = False
        End If
    End Sub
    Private Sub AddPress(btn As Button)
        '##########################
        '# Addition Button
        '##########################
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Add"
            Point = False
        End If
    End Sub
    Private Sub MultiplyPress(btn As Button)
        '##########################
        '# Multiply Button
        '##########################
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Multiply"
            Point = False
        End If
    End Sub
    Private Sub DividePress(btn As Button)
        '##########################
        '# Divide Button
        '##########################
        If txtDisplay.Text.Length <> 0 Then
            If Operation = String.Empty Then
                Num1 = CType(txtDisplay.Text, Double)
                txtDisplay.Text = "0"
            Else
                CalculateTotals()
            End If
            Operation = "Divide"
            Point = False
        End If
    End Sub
    Private Sub EnterPress(btn As Button)
        '##########################
        '# Enter Button
        '##########################
        If txtDisplay.Text.Length <> 0 Then
            CalculateTotals()
            Operation = String.Empty
            Point = False
        End If
    End Sub
End Class