Public Class Form1

    Dim temp As Integer = 0

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

        TextBox1.Text = temp

    End Sub

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

        temp = temp + 1
        TextBox1.Text = Integer.Parse(temp)
        'Integer.Parse(xxx)，將變數xxx轉換成Integer
    End Sub

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

        temp = temp - 1
        TextBox1.Text = Integer.Parse(temp)

    End Sub

End Class