Chapter Summary

Each class controls what happens when we copy, move, assign, or destroy objects of its type. Special member functions—the copy constructor, move constructor, copy-assignment operator, move-assignment operator, and destructor—define these operations. The move constructor and move-assignment operator take a (usually nonconst) rvalue reference; the copy versions take a (usually const) ordinary lvalue reference.

If a class declares none of these operations, the compiler will define them automatically. If not defined as deleted, these operations memberwise initialize, move, assign, or destroy the object: Taking each nonstatic data member in turn, the synthesized operation does whatever is appropriate to the member’s type to move, copy, assign, or destroy that member.

Classes that allocate memory or other resources almost always require that the class define the copy-control members to manage the allocated resource. If a class needs a destructor, then it almost surely needs to define the move and copy constructors and the move- and copy-assignment operators as well.