How can I use the memberwiseclone method in c#?

Richa Garg

The method MemberwiseClone is applied to many collections like arraylist etc,how can I implement this method?also give an example?

3 Replies

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Vulpes14y ago
Here's a simple example of using the MemberwiseClone method in C#.

Notice that the integer field is deep copied as it's a value type.

Even though it's a reference type, the string field is also deep copied as it's immutable - when a change is made a new string object is created rather than the old one being changed.

However, the reference type (SomeClass) is shallow copied - when a change is made to SomeInt it's still part of the same object and so the change is reflected in the clone:

using System;

class SomeClass
{
public int SomeInt {get; set;}
}

class MyClass
{
public int MyInt {get; set;} // value type
public string MyString {get; set;} // immutable reference type
public SomeClass SomeObject {get; set;} // mutable reference type

public MyClass(int myInt, string myString, SomeClass someObject)
{
MyInt = myInt;
MyString = myString;
SomeObject = someObject;
}

public MyClass Clone()
{
return (MyClass)MemberwiseClone();
}
}

class Test
{
static void Main()
{
SomeClass sc = new SomeClass();
sc.SomeInt = 42;
MyClass mc = new MyClass(1, "Hello", sc);

// now clone 'mc'
MyClass mc2 = mc.Clone();

// change 'mc'
mc.MyInt = 2;
mc.MyString = "Goodbye";
mc.SomeObject.SomeInt = 43;

// check 'mc2' to see what has changed

Console.WriteLine(mc2.MyInt); // still 1
Console.WriteLine(mc2.MyString); // still Hello
Console.WriteLine(mc2.SomeObject.SomeInt); // now 43
Console.ReadKey();
}
}
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Jignesh Trivedi14y ago
hi Richa,

The MemberwiseClone method creates a shallow copy by creating a new object, and then copying the nonstatic fields of the current object to the new object. If a field is a value type, a bit-by-bit copy of the field is performed. If a field is a reference type, the reference is copied but the referred object is not; therefore, the original object and its clone refer to the same object.

Please refer,

http://msdn.microsoft.com/en-us/library/system.object.memberwiseclone%28v=vs.80%29.aspx

http://dotnetgurukul.com/2011/02/24/cloning-in-c-shallow-copy-using-memberwiseclone-method/

hope this will help u.
0
Satyapriya Nayak14y ago
Hi Richa,

Please refer the below links

http://msdn.microsoft.com/en-us/library/system.object.memberwiseclone.aspx

http://buttle.shangorilla.com/1.1/handlers/monodoc.ashx?link=M%3ASystem.Object.MemberwiseClone

Thanks
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