Understanding const&, &, and && Specifiers for Member Functions in C

In C , member functions can be declared with const&, &, and && specifiers. While the return type of a member function is often the focus of discussion, these specifiers play a crucial role in determining the behavior of the member function.

const& Specification

The const& specifier indicates that the overload will be used for both const and non-const lvalue objects. An example of its usage is:

const A a = A();
*a;

In this example, the const& specifier allows the dereference operator (*) to be called on the const object a.

& Specification

The & specifier restricts the overload's use to non-const objects. An example of its usage is:

A a;
*a;

In this example, the & specifier ensures that the dereference operator (*) is only called on the non-const object a.

&& Specification

The && specifier limits the overload's use to rvalue objects. An example of its usage is:

*A();

In this example, the && specifier ensures that the dereference operator (*) is only called on the rvalue expression A().

Conclusion

The const&, &, and && specifiers for member functions provide a powerful means to control the behavior of member functions based on the type and value category of the object they are invoked on. This flexibility allows for more efficient and expressive code in C .