Vb. NET class Summary (i)

Module Module1

Sub Main ()
Dim Thefirstinstanceoftestscope as New testscope
Thefirstinstanceoftestscope.testscopesubmethodone ()
' Testscope.testscopesubmethodone ()
Dim aStr as String = Thefirstinstanceoftestscope.testscopefunctiongmethodone ()
Console.WriteLine (ASTR)
Console.ReadLine ()
End Sub

Class Testscope
Dim A As String ' acts like private A as String. The field of the class (also known as the member variable) defaults to private and instance types
Private B as String
Public C as String

Private Shared D as String

Sub New () ' No parameter constructor
Me. A = "Dim_a"
Me. B = "Private_b"
Me. C = "Public_c"
TESTSCOPE.D = "Private shared_d"
End Sub
' Public Static Sub Testscopemethodone () ' cannot declare a sub method (or Sub procedure) with Static, prompting an error: Method cannot be declared "Static"
Public Sub Testscopesubmethodone () is not accessible outside the class if it is changed to private
Console.WriteLine (String. Format ("Testscopesubmethodone (): {0} {1} {2}", A, B, c))
Console.WriteLine (TESTSCOPE.D) ' instance method can access shared members (in fact, static members)
Dim testscopefiled as New testscope
Testscopesharedsubmethodone (testscopefiled)
End Sub
The ' Public Static function Testscopefunctiongmethodone () as String ' cannot declare a function method (or function functions) with Static, prompting an error: The method cannot be declared as " Static "
The public Function Testscopefunctiongmethodone () as String ' cannot be accessed outside the class if it is changed to private
Return String. Format ("Testscopefunctiongmethodone (): {0} {1} {2}", A, B, c)
End Function

Public Shared Sub Testscopesharedsubmethodone (ByVal filedone as Testscope)
' Return String.Format (' Testscopefunctiongmethodone (): {0} {1} {2} ', A, B, c) ' ERROR: an instance of the class cannot be referenced from a shared method or a shared member initializer without an explicit instance of the class Rapporteur
' This error is the same as C #, and C # allows instance methods to access static methods and static fields, but C # does not allow static methods in classes and structs to access instance methods and instance fields in the same class or struct, VB. NET also complies with this rule.
Filedone.a = "Call the instance field of the Testscope class in the form of a pass parameter" but can invoke instance fields and instance methods with an instance of the class as a parameter to the method
Dim sharedmethodfiled as String = Filedone.testscopefunctiongmethodone () ' But you can call instance fields and instance methods with an instance of the class as a parameter to the method
Console.WriteLine ("{0}/{1}", Filedone.a, sharedmethodfiled)
' Fileone.testscopesubmethodone ()
Console.WriteLine ("Testscopefunctiongsharedmethodone")

Dim anotherfiled as New Testscope ' can also invoke instance fields of the class by instantiating the class in a static method
Console.WriteLine (anotherfiled) ' This method prints the object with an overloaded ToString method

End Sub
Public Overrides Function ToString () as String
' Return mybase.tostring ()
Return String. Format ("{0}::{1}::{2}", A, B, c)
End Function
End Class

End Module
"" Print the following--------------
' Testscopesubmethodone ():D im_a private_b Public_c
' Private shared_d
' Invokes an instance field of the Testscope class in the form of a pass parameter/testscopefunctiongmethodone (): Invokes an instance field of the Testscope class in the form of a pass parameter Private_b Public_c
' Testscopefunctiongsharedmethodone
' Dim_a::P rivate_b::P ublic_c
' Testscopefunctiongmethodone ():D im_a private_b Public_c

' ''''－－－－－－－－－－


' A little summary '
' You cannot use static to declare methods (sub and function) in vb.net, and you cannot declare member variables, only to declare static variables in methods (sub and function).
' Shared can be used to declare a variable or to declare a method, or to declare a member variable, which is just the opposite of static.
' Shared in Vb.ne is more like a static role in C #. The member variables (fields) and methods (sub and function) declared in vb.net with shared declarations can only be accessed using the class name, not with instances of the class

' Infinite loops and infinite recursion can result in an unhandled ' system.stackoverflowexception ' type of exception appearing in mscorlib.dll