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Missing Class

Represents a missing Object. This class cannot be inherited.

Namespace: System.Reflection
Assembly: mscorlib (in mscorlib.dll)

[SerializableAttribute] 
[ComVisibleAttribute(true)] 
public sealed class Missing : ISerializable
/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
public final class Missing implements ISerializable
SerializableAttribute 
ComVisibleAttribute(true) 
public final class Missing implements ISerializable
Not applicable.

Missing is used to invoke a method with a default argument.

Only one instance of Missing ever exists.

The following example shows how to use Missing to invoke a method with a default argument. To compile and run this code example, you must first compile the following Visual Basic code as a DLL assembly named Target.dll. Save the code as Target.vb. From the command line, use vbc /t:library Target.vb to compile the assembly.

Imports System

Public Class MissingSample
    
    Public Shared Sub MyMethod(Optional k As Integer = 33)
        Console.WriteLine("k = " & k.ToString())
    End Sub

End Class

If you compile Target.dll in Visual Studio, by default the project name is used as the name of a namespace that contains the MissingSample class. Either remove the namespace from the Target project, or add a using Target; statement to the C# code (Imports Target in Visual Basic, using namespace Target; in Visual C++).

NoteNote:

Visual Basic code is used for Target.dll because C# and Visual C++ do not support optional parameters in managed code. Optional parameters are not part of the Common Language Specification. Therefore, code that uses optional parameters is not CLS-compliant. For more information, see Writing CLS-Compliant Code.

When you compile the Visual Basic and C# versions of this code example, add references to Target.dll. For example, if you are compiling from the command line, use the /r:Target.dll option. The Visual C++ version of the code example already includes a #using statement for Target.dll.

Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class MissingSample
    
    Shared Sub Main()
        'To invoke MyMethod with a default argument, use the following syntax:
        GetType(MissingSample).GetMethod("MyMethod").Invoke(Nothing, New Object() {Missing.Value})
    End Sub     
    
    Shared Function MyMethod(Optional k As Integer = 33) As Integer
        Console.WriteLine("k = " & k.ToString())
        Return 0
    End Function
End Class

System.Object
  System.Reflection.Missing

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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