Rule of Five

Rule of 3 If you manage memory you need: Custom Destructor Custom Copy Constructor Custom Assignment Operator

Rule of 5 If you manage memory you need: You may want to provide: Custom Destructor Custom Copy Constructor Custom Assignment Operator You may want to provide: Move assignment operator Move copy constructor

Move semantics C++ allows us to specify that data should be moved from one place to another:

Moving Copy:

Moving Copy:

Moving Copy:

Moving Move:

Moving Move:

Moving Move:

Defining && = Rvalue reference Move constructor/assignment take rvalue reference: Move constructor:

Defining && = Rvalue reference Move constructor/assignment take rvalue reference: Move assignment:

Rule of 5 Why? But… Move can be more efficient than copying Never required for program correctness, just efficiency