Creates a shallow copy of the current Object.

[Visual Basic]
Protected Function MemberwiseClone() As Object
[C#]
protected object MemberwiseClone();
[C++]
protected: Object* MemberwiseClone();
[JScript]
protected function MemberwiseClone() : Object;

Return Value

A shallow copy of the current Object.

Remarks

This method cannot be overridden; a derived class must implement the ICloneable interface if a shallow copy is not appropriate. MemberwiseClone is protected and, therefore, is accessible only through this class or a derived class.

A shallow copy creates a new instance of the same type as the original object, and then copies the nonstatic fields of the original object. If the field is a value type, a bit-by-bit copy of the field is performed. If the field is a reference type, the reference is copied but the referred object is not; therefore, the reference in the original object and the reference in the clone point to the same object. In contrast, a deep copy of an object duplicates everything directly or indirectly referenced by the fields in the object.

For example, if X is an Object with references to the objects A and B, and the object A also has a reference to an object M, a shallow copy of X is an object Y, which also has references to objects A and B. In contrast, a deep copy of X is an object Y with direct references to objects C and D, and an indirect reference to object N, where C is a copy of A, D is a copy of B, and N is a copy of M.

The Type of the clone is the same as the type of the original Object.

Example

The following code example shows how to copy an instance of a class using MemberwiseClone.

[Visual Basic] 

Imports System

Class MyBaseClass
   Public Shared CompanyName As String = "My Company"
   Public age As Integer
   Public name As String
End Class 'MyBaseClass

Class MyDerivedClass
   Inherits MyBaseClass

   Shared Sub Main()

      ' Creates an instance of MyDerivedClass and assign values to its fields.
      Dim m1 As New MyDerivedClass()
      m1.age = 42
      m1.name = "Sam"

      ' Performs a shallow copy of m1 and assign it to m2.
      Dim m2 As MyDerivedClass = CType(m1.MemberwiseClone(), MyDerivedClass)

   End Sub 'Main

End Class 'MyDerivedClass

[C#] 
using System;

class MyBaseClass {
   public static string CompanyName = "My Company";
   public int age;
   public string name;
}

class MyDerivedClass: MyBaseClass {

   static void Main() {
   
   // Creates an instance of MyDerivedClass and assign values to its fields.
   MyDerivedClass m1 = new MyDerivedClass();
   m1.age = 42;
   m1.name = "Sam";

   // Performs a shallow copy of m1 and assign it to m2.
   MyDerivedClass m2 = (MyDerivedClass) m1.MemberwiseClone();
   }
}

[C++] 
#using <mscorlib.dll>

using namespace System;

__gc class MyBaseClass
{
public:
   static String* CompanyName;
   int age;
   String* name;
};

__gc class MyDerivedClass : public MyBaseClass
{
public:
   static void Test()
   {
      // Creates an instance of MyDerivedClass and assign values to its fields.
      MyDerivedClass* m1 = new MyDerivedClass();
      m1->age = 42;
      m1->name = S"Sam";

      // Performs a shallow copy of m1 and assign it to m2.
      MyDerivedClass* m2 = __try_cast<MyDerivedClass*>(m1->MemberwiseClone());
   }
};

void main()
{
   MyDerivedClass::Test();
}

[JScript] 
import System

class MyBaseClass {
   public static var CompanyName : String = "My Company";
   public var age : int;
   public var name : String;
}

class MyDerivedClass extends MyBaseClass {

   static function Main() {
   
   // Creates an instance of MyDerivedClass and assign values to its fields.
   var m1 : MyDerivedClass = new MyDerivedClass();
   m1.age = 42;
   m1.name = "Sam";

   // Performs a shallow copy of m1 and assign it to m2.
   var m2 : MyDerivedClass = MyDerivedClass(m1.MemberwiseClone());
   }
}

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework - Windows CE .NET, Common Language Infrastructure (CLI) Standard

See Also

Object Class | Object Members | System Namespace | ICloneable