Public Class Form1
    '//////////////CREATED BY ZEKI OZYILMAZ for CST112    
    'Declarations
    Private Sub B1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles B1.Click
        'Step0. Declarations
        Dim a, b, c As Double
        'Step1. Input
        a = geta()
        b = getb()
        'Step2. Process
        C = calcadd(a, b)
        'Step3. Output
        output(c)
    End Sub
    Function geta() As Double
        Dim s = Ta.Text
        Return Val(s)
    End Function
    Function getb() As Double
        Dim s = Tb.Text
        Return Val(s)
    End Function
    Function calcadd(ByVal a As Double, ByVal b As Double) As Double
        Return a + b
    End Function
    Sub output(ByVal c)
        ListBox1.Items.Add("The result is " & c)
    End Sub

    Private Sub B2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles B2.Click
        'Step0. Declarations
        Dim a, b, c As Double
        'Step1. Input
        a = geta()
        b = getb()
        'Step2. Process
        c = calcsub(a, b)
        'Step3. Output
        output(c)
    End Sub
    Function calcsub(ByVal a As Double, ByVal b As Double) As Double
        Return a - b
    End Function

    Private Sub BBigger_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BBigger.Click
        'Step0. Declarations
        Dim a, b, c As Double
        'Step1. Input
        a = geta()
        b = getb()
        'Step2. Process
        c = calcbig(a, b)
        'Step3. Output
        outputb(c)
    End Sub
    Function calcbig(ByVal a As Double, ByVal b As Double) As Double
        If a > b Then
            Return a
        Else
            Return b
        End If
    End Function
    Sub outputb(ByVal c)
        ListBox1.Items.Add("The bigger number is " & c)
    End Sub

    Private Sub BSmaller_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BSmaller.Click
        'Step0. Declarations
        Dim a, b, c As Double
        'Step1. Input
        a = geta()
        b = getb()
        'Step2. Process
        c = calcsmall(a, b)
        'Step3. Output
        outputs(c)
    End Sub
    Function calcsmall(ByVal a, ByVal b)
        If a > b Then
            Return b
        Else
            Return a
        End If
    End Function
    Sub outputs(ByVal c)
        ListBox1.Items.Add("The smaller number is " & c)
    End Sub

    Private Sub BQuit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BQuit.Click
        Dim n As Integer
        N = MsgBox("Do you want to quit?", MsgBoxStyle.YesNo, "Quitting?")
        If n = 6 Then
            Me.Close()
        End If
    End Sub
End Class