Sessions on advanced C++ programming

A.2. References

Topics

• The concept behind reference
  The concept behind reference is not easy to understand. In most of the programming languages we use declaration to allocate memory area and bind a name to that memory. Declaration of a reference and initialization it to a memory field is just a separation of this second action.
• Reference or value?
  There are subtle differences between using value or reference. One of the key difference is that pointers are individual memory areas, while references are often not stored. Other difference is the existence of null pointer, while references have no way to express invalid target. We give a number of examples when references are used and some when pointers are better.
• Parameter passing
  Reference parameters and const reference parameters are typical places when reference is used. There is a basic concept of parameter passing in C++ which originate in the concept of initialization. Initialization and assignment are different concepts in C++.
• Return type
  Return value of functions is another typical place where references are used. However this situation differs from the parameter passing: value return types and const reference are not logically interchangeble. We must learn where const ref is an efficiency improvement, and where is a mistake.