What do you mean by copy constructor in C#?

Hi Naresh,

To know more about Copy Constructor in C#, visit:

• https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/how-to-write-a-copy-constructor
• https://www.c-sharpcorner.com/UploadFile/0c1bb2/constructors-and-its-types-in-C-Sharp/
• https://www.tutorialspoint.com/What-is-a-copy-constructor-in-Chash
• https://www.geeksforgeeks.org/c-sharp-copy-constructor/

Thanks!

Copy Constructor creates an object by copying variables from another object.

using System;
namespace Demo {
   class Student {
      private string name;
      private int rank;

      public Student(Student s) {
         name = s.name;
         rank = s.rank;
      }

      public Student(string name, int rank) {
         this.name = name;
         this.rank = rank;
      }

      public string Display {
         get {
            return " Student " + name +" got Rank "+ rank.ToString();
         }
      }
   }

   class StudentInfo {
      static void Main() {
         Student s1 = new Student("Jack", 2);

         // copy constructor
         Student s2 = new Student(s1);

         // display
         Console.WriteLine(s2.Display);
         Console.ReadLine();
      }
   }
}

Above we saw, firstly we declared a copy constructor 

public Student(Student s)

Then a new object is created for the Student class 

Student s1 = new Student("Jack", 2);

Now, the s1 object is copied to a new object s2 

Student s2 = new Student(s1);

This is what we call copy constructor.

A constructor that creates an object by copying variables from another object or that copies the data of one object into another object is termed as the Copy Constructor. It is a parameterized constructor that contains a parameter of the same class type.

C# Copy Constructor Syntax

class User
{
     // Parameterized Constructor
     public User(string a, string b)
     {
         // your code
     }
     // Copy Constructor
     public User(User user) {
        // your code
     }
}

C# Copy Constructor Example

using System;

namespace Tutlane
{
     class User
     {
        public string name, location;
        // Parameterized Constructor
        public User(string a, string b)
        {
            name = a;
            location = b;
        }
        // Copy Constructor
        public User(User user)
        {
            name = user.name;
            location = user.location;
        }
     }
     class Program
     {
        static void Main(string[] args)
        {
            // User object with Parameterized constructor
            User user = new User("Raj Kumar", "Hyderabad");
            // Another User object (user1) by copying user details
            User user1 = new User(user);
            user1.name = "Goa Alavala";
            user1.location = "Delhi";
            Console.WriteLine(user.name + ", " + user.location);
            Console.WriteLine(user1.name + ", " + user1.location);
            Console.WriteLine("\nPress Enter Key to Exit..");
            Console.ReadLine();
        }
     }
}

 

OutPut:

Raj Kumar, Hyderabad
Goa Alavala, Delhi

Press Any key to Exit