ASP.NET 语法

Microsoft .NET Platform 目前提供对以下三种语言的内置支持：C#、Visual Basic、JScript。
  1. 变量声明
  2. 语句
  3. 注释
  4. 访问索引属性
  5. 声明索引属性
  6. 声明简单属性
  7. 声明和使用枚举
  8. 枚举集合
  9. 声明和使用方法
  10. 自定义属性
  11. 数组
  12. 初始化
  13. IF 语句
  14. CASE 语句
  15. FOR 循环
  16. WHILE 循环
  17. 异常处理
  18. 字符串连接
  19. 事件处理程序委托
  20. 声明事件
  21. 向事件添加事件处理程序或从事件移除事件处理程序
  22. 强制类型转换
  23. 转换
  24. 带继承的类定义
  25. 实现接口
  26. 带 Main 方法的类定义
  27. 标准模块

变量声明 


Dim x As Integer
Dim s As String
Dim s1, s2 As String
Dim o 'Implicitly Object
Dim obj As New Object()
Public name As String
C# VB JScript  

语句 


Response.Write("foo")
C# VB JScript  

注释 


' This is a comment

' This
' is
' a
' multiline
' comment
C# VB JScript  

访问索引属性 


Dim s, value As String
s = Request.QueryString("Name")
value = Request.Cookies("Key").Value

'Note that default non-indexed properties
'must be explicitly named in VB
C# VB JScript  

声明索引属性 


' Default Indexed Property
Public Default ReadOnly Property DefaultProperty(Name As String) As String
    Get
        Return CStr(lookuptable(name))
    End Get
End Property
C# VB JScript  

声明简单属性 


Public Property Name As String

  Get
    ...
    Return ...
  End Get

  Set
    ... = Value
  End Set

End Property
C# VB JScript  

声明和使用枚举 


' Declare the Enumeration
Public Enum MessageSize

    Small = 0
    Medium = 1
    Large = 2
End Enum

' Create a Field or Property
Public MsgSize As MessageSize

' Assign to the property using the Enumeration values
MsgSize = small
C# VB JScript  

枚举集合 


Dim S As String
For Each S In Coll
 ...
Next
C# VB JScript  

声明和使用方法 


' Declare a void return function
Sub VoidFunction()
 ...
End Sub

' Declare a function that returns a value
Function StringFunction() As String
 ...
    Return CStr(val)
End Function

' Declare a function that takes and returns values
Function ParmFunction(a As String, b As String) As String
 ...
    Return CStr(A & B)
End Function

' Use the Functions
VoidFunction()
Dim s1 As String = StringFunction()
Dim s2 As String = ParmFunction("Hello", "World!")
C# VB JScript  

自定义属性 


' Stand-alone attribute
<STAThread>

' Attribute with parameters
<DllImport("ADVAPI32.DLL")>

' Attribute with named parameters
<DllImport("KERNEL32.DLL", CharSet:=CharSet.Auto)>
C# VB JScript  

数组 


    Dim a(2) As String
    a(0) = "1"
    a(1) = "2"
    a(2) = "3"

    Dim a(2,2) As String
    a(0,0) = "1"
    a(1,0) = "2"
    a(2,0) = "3"
C# VB JScript  

初始化 


Dim s As String = "Hello World"
Dim i As Integer = 1
Dim a() As Double = { 3.00, 4.00, 5.00 }
C# VB JScript  

If 语句 


If Not (Request.QueryString = Nothing)
  ...
End If
C# VB JScript  

Case 语句 


Select Case FirstName
  Case "John"
    ...
  Case "Paul"
    ...
  Case "Ringo"
    ...
  Case Else
    ...
End Select
C# VB JScript  

For 循环 


  Dim I As Integer
  For I = 0 To 2
    a(I) = "test"
  Next
C# VB JScript  

While 循环 


Dim I As Integer
I = 0
Do While I < 3
  Console.WriteLine(I.ToString())
  I += 1
Loop
C# VB JScript  

异常处理 


Try
    ' Code that throws exceptions
Catch E As OverflowException
    ' Catch a specific exception
Catch E As Exception
    ' Catch the generic exceptions
Finally
    ' Execute some cleanup code
End Try
C# VB JScript  

字符串连接 


' Using Strings
Dim s1, s2 As String
s2 = "hello"
s2 &= " world"
s1 = s2 & " !!!"

' Using StringBuilder class for performance
Dim s3 As New StringBuilder()
s3.Append("hello")
s3.Append(" world")
s3.Append(" !!!")
C# VB JScript  

事件处理程序委托 


Sub MyButton_Click(Sender As Object,
                   E As EventArgs)
...
End Sub
C# VB JScript  

声明事件 


' Create a public event
Public Event MyEvent(Sender as Object, E as EventArgs)

' Create a method for firing the event
Protected Sub OnMyEvent(E As EventArgs)
    RaiseEvent MyEvent(Me, E)
End Sub
C# VB JScript  

向事件添加事件处理程序或从事件移除事件处理程序 


AddHandler Control.Change, AddressOf Me.ChangeEventHandler
RemoveHandler Control.Change, AddressOf Me.ChangeEventHandler
C# VB JScript  

强制类型转换 


Dim obj As MyObject
Dim iObj As IMyObject
obj = Session("Some Value")
iObj = CType(obj, IMyObject)
C# VB JScript  

转换 


Dim i As Integer
Dim s As String
Dim d As Double

i = 3
s = i.ToString()
d = CDbl(s)

' See also CDbl(...), CStr(...), ...
C# VB JScript  

带继承的类定义 


Imports System

Namespace MySpace

  Public Class Foo : Inherits Bar

    Dim x As Integer

    Public Sub New()
      MyBase.New()
      x = 4
    End Sub

    Public Sub Add(x As Integer)
      Me.x = Me.x + x
    End Sub

    Overrides Public Function GetNum() As Integer
       Return x
    End Function

  End Class

End Namespace

' vbc /out:libraryvb.dll /t:library
' library.vb
C# VB JScript  

实现接口 


Public Class MyClass : Implements IEnumerable
 ...

    Function IEnumerable_GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
         ...
    End Function
End Class
C# VB JScript  

带 Main 方法的类定义 


Imports System

Public Class ConsoleVB

  Public Sub New()
    MyBase.New()
    Console.WriteLine("Object Created")
  End Sub

  Public Shared Sub Main()
    Console.WriteLine("Hello World")
    Dim cvb As New ConsoleVB
  End Sub

End Class

' vbc /out:consolevb.exe /t:exe console.vb
C# VB JScript  

标准模块 


Imports System

Public Module ConsoleVB

  Public Sub Main()
    Console.WriteLine("Hello World")
  End Sub

End Module

' vbc /out:consolevb.exe /t:exe console.vb
C# VB JScript