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What Is An Eligible Copy Constructor In C++ Software?

What Is An Eligible Copy Constructor In C++ Software

Do you want to learn what is Eligible Copy Constructor or what kind of methods are available to declare and use an Eligible Copy Constructor? In this post, we will try to explain the Eligible Copy Constructor with examples. First, let’s remind ourselves of the Constructor and Copy Constructor meaning in C+++ software.

What is a Constructor in C++ software?

The Constructor in C++ is a function, a method in the class, but it is a ‘special method’ that is automatically called when an object of a class is created. We don’t need to call this function. Whenever a new object of a class is created, the Constructor allows the class to initialize member variables or allocate storage. This is why the name Constructor is given to this special method. Here is a simple constructor class example below,

There are different constructor types in classes and the Copy Constructor is one of these. Copy Constructors not only used in classes but also used with struct and union data types

The Copy Constructor in classes (class_name) is a non-template constructor whose first parameter is class_name&‍, const class_name&‍, volatile class_name&‍, or const volatile class_name&‍ . It can be used with no other parameters or with the rest of the parameters all have default values.

The Copy Constructor is a constructor type for classes that class_name must name the current class, or it should be a qualified class name when it is declared at namespace scope or in a friend declaration.

What is a C++ Eligible Copy Constructor?

Since C++11, a copy constructor is defined as eligible if it is not deleted.

Since C++20, a copy constructor is eligible if

  • Copy Constructor is not deleted, and
  • Copy Constructor associated constraints, if any, are satisfied,
  • no copy constructor with the same first parameter type is more constrained than it

The triviality of eligible copy constructors determines whether the class is an implicit-lifetime type and whether the class is a trivially copyable type.

Here is a full C++ example of using an Eligible Copy Constuctor


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About author

Dr. Yilmaz Yoru has 35+ years of coding with more than 30+ programming languages, mostly C++ on Windows, Android, Mac-OS, iOS, Linux, and some other operating systems. He graduated and received his MSc and PhD degrees from the Department of Mechanical Engineering of Eskisehir Osmangazi University. He is the founder and CEO of ESENJA LLC Company. His interests are Programming, Thermodynamics, Fluid Mechanics, Artificial Intelligence, 2D & 3D Designs, and high-end innovations.
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