|
bsp; d = 1
End If
CompareWithInteger = d
End Function
Public Function CompareWithRectangle(ByVal r As Rectangle) As Integer
Dim d As Integer
d = Area() - r.Area()
If d <> 0 Then
d = 1
End If
CompareWithRectangle = d
End Function
Public Function CompareTwoRectangle( ByVal x As Rectangle, ByVal
y As Rectangle) As Integer
Dim d As Integer
d = x.Area() - y.Area()
If d <> 0 Then
d = 1
End If
CompareTwoRectangle = d
End Function
End Class
''''---------------------------------------------------------------------------------------------
Public Class Form1
Inherits System.WinForms.Form
Public Sub New()
MyBase.New()
Form1 = Me
''''This call is required by the Win Form Designer.
InitializeComponent()
''''TODO: Add any initialization after the InitializeComponent() call
End Sub
''''Form overrides dispose to clean up the component list.
Public Overrides Sub Dispose()
MyBase.Dispose()
components.Dispose()
End Sub
#Region " Windows Form Designer generated code "
........
#End Region
Protected Sub Form1_Click( ByVal sender As Object, ByVal
e As System.EventArgs)
Dim r1 As New Rectangle(10, 50)
Dim r2 As New Rectangle(20, 25)
If r1.CompareWithInteger(400) = 0 Then
MessageBox.Show("ggg EQUAL")
Else
MessageBox.Show("NOT EQUAL")
End If
If r1.CompareWithRectangle(r2) = 0 Then
MessageBox.Show("EQUAL")
Else
MessageBox.Show("NOT EQUAL")
End If
If r1.CompareTwoRectangle(r1, r2) = 0 Then
MessageBox.Show("EQUAL")
Else
MessageBox.Show("NOT EQUAL")
End If
End Sub
End Class
此程序输出﹕
NOT EQUAL
EQUAL
EQUAL
由于各程序名称不相同，您就得记忆各程序之名字﹐徒增记忆负担而且易于犯错﹐并不合乎人们生活习惯。因之﹐VB的多重定义观念﹐能增加程序之弹性及亲切感。
程序多重定义情形并不限于单一类别之内，也可以发生于父子类别之间。例如：
''''ex06.bas
Imports System.ComponentModel
Imports System.Drawing
Imports System.WinForms
''''------------------------------------------------------------------------------------------
Public Class Person
Private name As String
Private age As Integer
Public Sub New()
End Sub
Public Sub SetValue(ByVal na As String, ByVal a As Integer)
name = na
age = a
End Sub
Public Function birthDay() As Integer
birthDay = 2001 - age
End Function
Public Sub Display()
Messagebox.Show("Name: " + name + " Age: " + str(age))
End Sub
End Class
Public Class Teacher
Inherits Person
Private salary As Decimal
Public Overloads Sub SetValue( ByVal na As String, ByVal a As Integer, ByVal
sa As Decimal)
SetValue(na, a)
salary = sa
End Sub
Public Sub pr()
MyBase.Display()
Messagebox.Show("Salary: " + str(salary))
End Sub
End Class
Public Class Student
Inherits Person
Private student_number As Integer
Public Overloads Sub SetValue( ByVal na As String, ByVal a As Integer, ByVal
no As Integer)
SetValue(na, a)
student_number = no
End Sub
Public Sub pr()
MyBase.Display()
Messagebox.Show("StudNo: " + str(student_number))
End Sub
End Class
''''-----------------------------------------------------------------------------------------
Public Class Form1
Inherits System.WinForms.Form
Public Sub New()
MyBase.New()
Form1 = Me
''''This call is required by the Win Form Designer.
InitializeComponent()
''''TODO: Add any initialization after the InitializeComponent() call
End Sub
''''Form overrides dispose to clean up the component list.
Public Overrides Sub Dispose()
MyBase.Dispose()
components.Dispose()
End Sub
#Region " Windows Form Designer generated code "
........
#End Region
Protected Sub Form1_Click( ByVal sender As Object, ByVal
e As System.EventArgs)
Dim x As New Person()
x.SetValue("Alvin", 32)
Dim y As New Student()
y.SetValue("Tom", 36, 11138)
x.Display()
y.pr()
End Sub
End Class
Teacher类别从Person继承了SetValue() ──
SetValue(ByVal na As String, ByVal a As Integer)
自己又重复定义一个新的SetValue()程序──
SetValue(ByVal na As String, ByVal a As Integer, ByVal no As Integer)
共有两个SetValue()可用。指令x.SetValue("Alvin", 32)呼叫第1个SetValue()；指令y.SetValue("Tom", 36, 11138)呼叫第1个SetValue()。
兹在扩充一个子类别如下：
''''ex07.bas
Imports System.ComponentModel
Imports System.Drawing
Imports System.WinForms
''''------------------------------------------------------------------------------------------
Public Class Person
Private name As String
Private age As Integer
Public Sub New()
End Sub
Public Sub SetValue(ByVal na As String, ByVal a As Integer)
name = na
age = a
End Sub
Public Function birthDay() As Integer
birthDay = 2001 - age上一页 [1] [2] [3] [4] 下一页
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