how-to-write-a-copy-constructor.md

title	description	ms.date	helpviewer_keywords	ms.topic	ms.assetid
How to write a copy constructor - C# Programming Guide	Learn how to write a copy constructor in C# that takes an instance of class and returns a new instance with the values of the input.	05/24/2023	C# Language, copy constructor copy constructor [C#]	how-to	fba899b5-fc41-428e-a745-3ebdbf37990a

How to write a copy constructor (C# Programming Guide)

C# records provide a copy constructor for objects, but for classes you have to write one yourself.

Important

Writing copy constructors that work for all derived types in a class hierarchy can be difficult. If your class isn't sealed, you should strongly consider creating a hierarchy of record class types to use the compiler-synthesized copy constructor.

Example

In the following example, the Person class defines a copy constructor that takes, as its argument, an instance of Person. The values of the properties of the argument are assigned to the properties of the new instance of Person. The code contains an alternative copy constructor that sends the Name and Age properties of the instance that you want to copy to the instance constructor of the class. The Person class is sealed, so no derived types can be declared that could introduce errors by copying only the base class.

:::code source="snippets/how-to-write-a-copy-constructor/Program.cs" :::

See also

• xref:System.ICloneable
• Records
• C# Programming Guide
• The C# type system
• Constructors
• Finalizers