(C++) Big Six

Since C++11 the Big Six are the following six special class member functions:

1. Default constructor
2. Copy constructor
3. Move constructor
4. Copy assignment operator
5. Move assignment operator
6. Destructor

In C++98 there were only four, called the Big Four.

Example

 

#include <iostream>

///Gossip is a class that tells you what is happening to it
struct Gossip
{
  Gossip() { std::cout << "Default constructor\n"; }
  Gossip(const Gossip&) { std::cout << "Copy constructor\n"; }
  Gossip(const Gossip&&) { std::cout << "Move constructor\n"; }
  ~Gossip() { std::cout << "Destructor\n"; }
  Gossip& operator=(const Gossip&) { std::cout << "Copy assignment operator\n"; }
  Gossip& operator=(const Gossip&&) { std::cout << "Move assignment operator\n"; }
};

int main()
{
  {
    Gossip g; //Default constructor
    const Gossip h(g); //Copy constructor
    g = h; //Copy assignment operator
    //Destructor of g and h
  }
}

Screen output:

Default constructor
Copy constructor
Copy assignment operator
Destructor
Destructor
``` 

## Advice

-   Regarding the six operations above, implement as little as possible and declare as much as possible. Any operation not
    implemented shall be declared as default or delete [1]

## [References](CppReferences.md)

1.  Gottschling, Peter. Discovering Modern C++: An Intensive Course for Scientists, Engineers, and Programmers. Addison-Wesley Professional, 2015.
    Chapter 2.5: 'Regarding the six operations above, implement as little as possible and declare as much as possible. Any operation not
    implemented shall be declared as default or delete'