How to Copy a Object in C#

1. Copy an Object With the MemberWiseClone() Method in C#
2. Copy an Object With the Parameterized Constructor Method in C#

This tutorial will introduce methods to copy an object in C#.

Copy an Object With the MemberWiseClone() Method in C#

Unfortunately, there is no built-in way of creating a separate copy of an object in C#. This phenomenon is demonstrated in the following code example.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace copy_an_object {
  class myClass {
    public String test;
  }
  class Program {
    static void Main(string[] args) {
      myClass a = new myClass();
      a.test = "This is a test";
      myClass b = a;
      b.test = "This is not a test";
      Console.WriteLine(a.test);
      Console.WriteLine(b.test);
    }
  }
}

Output:

This is not a test
This is not a test

We get the same output both times because an instance of a class in C# is a reference-type variable that points to a specific memory location. Due to the Object-Oriented nature of C#, the new pointer b is also pointing to the memory location of a.

If we want to create a separate memory location for b, we have to rely on some user-defined approaches. The MemberWiseClone() method is used to create a separate copy of the values of the calling object in C#. The return type of the MemberWiseClone() function is object. The following code example shows us how to create a separate copy of a class object with the MemberWiseClone() function in C#.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace copy_an_object {
  class myClass {
    public String test;
    public object Clone() {
      return this.MemberwiseClone();
    }
  }
  class Program {
    static void Main(string[] args) {
      myClass a = new myClass();
      a.test = "This is a test";
      myClass b = (myClass)a.Clone();
      b.test = "This is not a test";
      Console.WriteLine(a.test);
      Console.WriteLine(b.test);
    }
  }
}

Output:

This is a test
This is not a test

This time it is clear from the output that there is a separate copy for each class object. We implemented the MemberWiseClone() function inside the Clone() function of the myClass class. The Clone() function returns a separate copy of the class object. The return value of the Clone() function is type-casted to myClass and pointed to by the b class object.

Copy an Object With the Parameterized Constructor Method in C#

We can create a parameterized class constructor to achieve the same goal in C#. We can pass the previous class object to the constructor of a new class object and copy all the values from it. The following code example shows us how we can create a separate copy of a class object with the parameterized constructor method in C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace copy_an_object {
  class MyClass {
    public String test;

    public MyClass() {}

    public MyClass(MyClass other) {
      test = other.test;
    }
  }
  class Program {
    static void Main(string[] args) {
      MyClass a = new myClass();
      a.test = "This is a test";
      MyClass b = new MyClass(a);
      b.test = "This is not a test";
      Console.WriteLine(a.test);
      Console.WriteLine(b.test);
    }
  }
}

Output:

This is a test
This is not a test

We created a parameterized constructor for the MyClass class that takes an object of the MyClass class and copies the test string from it. In the main function, we created the object a of the MyClass class and passed it to the constructor of b.