factorialform.vb

this is a function for calculating factorial

Public Class Form1
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Public Overrides Sub Dispose()
        MyBase.Dispose()
        If Not (components Is Nothing) Then
            components.Dispose()
        End If
    End Sub
    Private WithEvents Button1 As System.Windows.Forms.Button
    Private WithEvents TextBox1 As System.Windows.Forms.TextBox
    Private WithEvents TextBox2 As System.Windows.Forms.TextBox

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.Container

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.Button1 = New System.Windows.Forms.Button()
        Me.TextBox2 = New System.Windows.Forms.TextBox()
        Me.TextBox1 = New System.Windows.Forms.TextBox()
        Me.SuspendLayout()
        '
        'Button1
        '
        Me.Button1.Font = New System.Drawing.Font("Tahoma", 11.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.Button1.Location = New System.Drawing.Point(96, 24)
        Me.Button1.Name = "Button1"
        Me.Button1.Size = New System.Drawing.Size(144, 26)
        Me.Button1.TabIndex = 0
        Me.Button1.Text = "Calculate Factorial"
        '
        'TextBox2
        '
        Me.TextBox2.Font = New System.Drawing.Font("Tahoma", 11.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.TextBox2.Location = New System.Drawing.Point(256, 24)
        Me.TextBox2.Name = "TextBox2"
        Me.TextBox2.Size = New System.Drawing.Size(144, 26)
        Me.TextBox2.TabIndex = 2
        Me.TextBox2.Text = ""
        '
        'TextBox1
        '
        Me.TextBox1.Font = New System.Drawing.Font("Tahoma", 11.25!, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.TextBox1.Location = New System.Drawing.Point(24, 24)
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.Size = New System.Drawing.Size(56, 26)
        Me.TextBox1.TabIndex = 1
        Me.TextBox1.Text = "10"
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(408, 85)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.TextBox2, Me.TextBox1, Me.Button1})
        Me.Name = "Form1"
        Me.Text = "Factorial"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        TextBox2.Text = Factorial(TextBox1.Text)
    End Sub

    Function Factorial(ByVal n As Integer) As Long
        Console.WriteLine("Starting the calculation of " & n & " factorial")
        If n = 0 Then
            Factorial = 1
        Else
            Console.WriteLine("Calling Factorial(" & n - 1 & ")")
            Factorial = Factorial(n - 1) * n
        End If
        Console.WriteLine("Done calculating " & n & " factorial")
    End Function
End Class