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vb.net基本案例练习 vb案例教程视频

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VB中的CASE语句在VB.NET中VB.NET CASE语句就是比较常用的一种，下面是详细的介绍和代码的演示：
1、可以用 Select...Case 语句来替换 If...Then...Else 语句，所不同的是If 和 ElseIf 语句可在每个语句中计算不同的表达式，而 Select 语句对单个表达式只计算一次，然后将其和不同的值比较 。
Function bonus(ByVal performance As Integer, _ByVal salary As Decimal) As Decimal
Select performance
Case 1
Return salary * 0.1
Case 2
Return salary * 0.3
Case 3
Return salary * 0.7
Case 4
Return salary * 0.9
Case 5
Return salary * 1.2
End Select
End Function
2、VB.NET Case语句可包含多个值和某个范围的值 ， 代码案例如下：
Function bonus(ByVal performance As Integer, _ByVal salary As Decimal) As Decimal
Select performance
Case 1
Return salary * 0.1
Case 2,3
Return salary * 0.3
Case 3 To 7
Return salary * 0.7
Case 8 To 9
Return salary * 0.9
Case Is = 15
Return salary * 1.2
Case Else
Return 0
End Select
End Function
VB.net中正则表达式实例在所给代码基础上仅作修改.
首先导入命名空间
Imports System.Text.RegularExpressions
然后:
Function geta(ByVal Str)
Dim re As New Regex("a(. ?)href=""*([^\s] ?)""*(\s|)")
Dim Contents As MatchCollection = re.Matches(Str)
Dim links As String = Nothing
For Each Match In Contents ' 遍历匹配集合 。
links = linksMatch.SubMatches(1)"|"
Next
geta = Mid(links, 1, Len(links) - 1)
geta = Replace(geta, "'", "")
re = Nothing
End Function
vb.net中如何用事件和委托，会C#中的事件和委托，但不知VB.net中的语法，望给个简单的例子熟悉语法 。一委托：此示例演示如何将方法与委托关联然后通过委托调用该方法 。
创建委托和匹配过程
创建一个名为 MySubDelegate 的委托 。
Delegate Sub MySubDelegate(ByVal x As Integer)
声明一个类 ， 该类包含与该委托具有相同签名的方法 。
Class class1
Sub Sub1(ByVal x As Integer)
MsgBox("The value of x is: "CStr(x))
End Sub
End Class
定义一个方法，该方法创建该委托的实例并通过调用内置的 Invoke 方法调用与该委托关联的方法 。
Protected Sub DelegateTest()
Dim c1 As New class1
' Create an instance of the delegate.
Dim msd As MySubDelegate = AddressOf c1.Sub1
' Call the method.
msd.Invoke(10)
End Sub
二、事件
下面的示例程序阐释如何在一个类中引发一个事件 ， 然后在另一个类中处理该事件 。AlarmClock 类定义公共事件 Alarm，并提供引发该事件的方法 。AlarmEventArgs 类派生自 EventArgs，并定义 Alarm 事件特定的数据 。WakeMeUp 类定义处理 Alarm 事件的 AlarmRang 方法 。AlarmDriver 类一起使用类，将使用 WakeMeUp 的 AlarmRang 方法设置为处理 AlarmClock 的 Alarm 事件 。
该示例程序使用事件和委托和引发事件中详细说明的概念 。
示例
' EventSample.vb.
'
Option Explicit
Option Strict
Imports System
Imports System.ComponentModel
Imports Microsoft.VisualBasic
Namespace EventSample
' Class that contains the data for
' the alarm event. Derives from System.EventArgs.
'
Public Class AlarmEventArgs
Inherits EventArgs
Private _snoozePressed As Boolean
Private nrings As Integer
'Constructor.
'
Public Sub New(snoozePressed As Boolean, nrings As Integer)
Me._snoozePressed = snoozePressed
Me.nrings = nrings
End Sub
' The NumRings property returns the number of rings
' that the alarm clock has sounded when the alarm event
' is generated.
'
Public ReadOnly Property NumRings() As Integer
Get
Return nrings
End Get
End Property
' The SnoozePressed property indicates whether the snooze
' button is pressed on the alarm when the alarm event is generated.
'
Public ReadOnly Property SnoozePressed() As Boolean
Get
Return _snoozePressed
End Get
End Property
' The AlarmText property that contains the wake-up message.
'
Public ReadOnly Property AlarmText() As String
Get
If _snoozePressed Then
Return "Wake Up!!! Snooze time is over."
Else
Return "Wake Up!"
End If
End Get
End Property
End Class
' Delegate declaration.
'
Public Delegate Sub AlarmEventHandler(sender As Object, _
e As AlarmEventArgs)
' The Alarm class that raises the alarm event.
'
Public Class AlarmClock
Private _snoozePressed As Boolean = False
Private nrings As Integer = 0
Private stopFlag As Boolean = False
' The Stop property indicates whether the
' alarm should be turned off.
'
Public Property [Stop]() As Boolean
Get
Return stopFlag
End Get
Set
stopFlag = value
End Set
End Property
' The SnoozePressed property indicates whether the snooze
' button is pressed on the alarm when the alarm event is generated.
'
Public Property SnoozePressed() As Boolean
Get
Return _snoozePressed
End Get
Set
_snoozePressed = value
End Set
End Property
' The event member that is of type AlarmEventHandler.
'
Public Event Alarm As AlarmEventHandler
' The protected OnAlarm method raises the event by invoking
' the delegates. The sender is always this, the current instance
' of the class.
'
Protected Overridable Sub OnAlarm(e As AlarmEventArgs)
RaiseEvent Alarm(Me, e)
End Sub
' This alarm clock does not have
' a user interface.
' To simulate the alarm mechanism it has a loop
' that raises the alarm event at every iteration
' with a time delay of 300 milliseconds,
' if snooze is not pressed. If snooze is pressed,
' the time delay is 1000 milliseconds.
'
Public Sub Start()
Do
nrings= 1
If stopFlag Then
Exit Do
Else
If _snoozePressed Then
System.Threading.Thread.Sleep(1000)
If (True) Then
Dim e As New AlarmEventArgs(_snoozePressed, nrings)
OnAlarm(e)
End If
Else
System.Threading.Thread.Sleep(300)
Dim e As New AlarmEventArgs(_snoozePressed, nrings)
OnAlarm(e)
End If
End If
Loop
End Sub
End Class
' The WakeMeUp class has a method AlarmRang that handles the
' alarm event.
'
Public Class WakeMeUp
Public Sub AlarmRang(sender As Object, e As AlarmEventArgs)
Console.WriteLine((e.AlarmTextControlChars.Cr))
If Not e.SnoozePressed Then
If e.NumRings Mod 10 = 0 Then
Console.WriteLine(" Let alarm ring? Enter Y")
Console.WriteLine(" Press Snooze? Enter N")
Console.WriteLine(" Stop Alarm? Enter Q")
Dim input As String = Console.ReadLine()
If input.Equals("Y") Or input.Equals("y") Then
Return
Else
If input.Equals("N") Or input.Equals("n") Then
CType(sender, AlarmClock).SnoozePressed = True
Return
Else
CType(sender, AlarmClock).Stop = True
Return
End If
End If
End If
Else
Console.WriteLine(" Let alarm ring? Enter Y")
Console.WriteLine(" Stop Alarm? Enter Q")
Dim input As String = Console.ReadLine()
If input.Equals("Y") Or input.Equals("y") Then
Return
Else
CType(sender, AlarmClock).Stop = True
Return
End If
End If
End Sub
End Class
' The driver class that hooks up the event handling method of
' WakeMeUp to the alarm event of an Alarm object using a delegate.
' In a forms-based application, the driver class is the
' form.
'
Public Class AlarmDriver
Public Shared Sub Main()
' Instantiates the event receiver.
Dim w As New WakeMeUp()
' Instantiates the event source.
Dim clock As New AlarmClock()
' Wires the AlarmRang method to the Alarm event.
AddHandler clock.Alarm, AddressOf w.AlarmRang
clock.Start()
End Sub
End Class
End Namespace
急！VB.NET 用SOCKET实现数据交换案例rivate Shared Function ConnectSocket(ByVal server As String, ByVal port As Integer) As Socket'创建连接
Dim s As Socket = Nothing
Dim hostEntry As IPHostEntry = Nothing
Dim address As IPAddress
address = System.Net.IPAddress.Parse(server)
Dim endPoint As New IPEndPoint(address, port)
Dim tempSocket As New Socket(endPoint.AddressFamily, SocketType.Stream, ProtocolType.Tcp)
tempSocket.Connect(endPoint)
If tempSocket.Connected Then
s = tempSocket
End If
Return s
End Function
调用vb.net基本案例练习：s = ConnectSocket(IP地址, 端口)'端口号如8000,8080等
s.close'关闭连接
VB.NET 拖动无边框窗体编程实例 Imports System Drawing Imports System Windows Forms****************************************** Private oOriginalRegion As Region = Nothing用于窗体移动 Private bFormDragging As Boolean = False Private oPointClicked As Point****************************************** Private Sub Form _MouseDown(ByVal sender As Object ByVal e As System Windows Forms MouseEventArgs) Handles MyBase MouseDown Me bFormDragging = True Me oPointClicked = New Point(e X e Y) End Sub****************************************** Private Sub Form _MouseUp(ByVal sender As Object ByVal e As System Windows Forms MouseEventArgs) Handles MyBase MouseUp Me bFormDragging = False End Sub****************************************** Private Sub Form _MouseMove(ByVal sender As Object ByVal e As System Windows Forms MouseEventArgs) Handles MyBase MouseMove If Me bFormDragging Then Dim oMoveToPoint As Point以当前鼠标位置为基础 找出目标位置 oMoveToPoint = Me PointToScreen(New Point(e X e Y))根据开始位置作出调整 oMoveToPoint Offset(Me oPointClicked X * _ (Me oPointClicked Y_ SystemInformation CaptionHeight_ SystemInformation BorderSize Height) * )移动窗体 Me Location = oMoveToPoint End If
lishixinzhi/Article/program/ASP/201311/21755
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