综合实例（相关vb.net教程)
用定义类的方法编程序，对任输入的矩形的两边，求其周长与面积，并对输入的两边进行正确性检查。见，矩形的两边求面积与周长类，程序为：[实验报告7]  或类的应用矩形问题
Public Class juxing
    Public w, h As Integer
    Public Sub New()
        w = 0 : h = 0
    End Sub
    Public Sub New(ByVal a As Integer, ByVal b As Integer)
        If a >= 0 Then
            w = a
        Else
            MsgBox("无效的矩形长度,即将退出！", MsgBoxStyle.OkOnly, "提示")
            End
        End If
        If b >= 0 Then
            h = b
        Else
            MsgBox("无效的矩形高度,即将退出！", MsgBoxStyle.OkOnly, "提示")
            End
        End If
    End Sub
    Public Function zhouchang(ByVal w As Integer, ByVal h As Integer) As Integer
        zhouchang = 2 * (w + h)
    End Function
    Public Function area(ByVal w As Integer, ByVal h As Integer) As Double
        area = w * h
    End Function
End Class
测试类为：
Public Class Form1
    Dim x, y As Integer
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim p As Integer
        Dim s As Double
        x = InputBox("输入矩形的长度", "输入", 1)
        y = InputBox("输入矩形的高度", "输入", 1)
        Dim a As New juxing(x, y)
        p = a.zhouchang(x, y)
        s = a.area(x, y)
        Console.WriteLine("矩形的两边为：" & x & "  " & y)
        Console.WriteLine("矩形的周长为：" & p)
        Console.WriteLine("矩形的面积为：" & s)
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        End
    End Sub
End Class