/fluent-cpp-dailies

Actually coding out Fluent C++ Dailies

Fluent C++ Dailies

Notes and hands on coding of Fluent C++ Dailies Posts

  1. class vs struct

  • The legal difference is that the class members are private by default, struct members are public by default.

  • struct is more commonly used to "bundle" together related elements in a certain context. It can also be used effectively to raise the level of abstraction to make function interfaces cleaner.

  • class is about "doing things" - users of a class isn't supposed to know the context of the class, they care about the responsibility of the class ("what it does"), via the interface.

  • A class contains invariants - a relation between a class' data members in order for the class methods to work correctly. Ex: For a std::string that holds a char* and an int size, the invariant is the number of characters in the allocated cahr buffer must match the value of size memeber.

Invariants are set in place by the class constructor, and the class methods assue that all invariants are true when the methods are called, and ensure that they remain true until the end.

  • Rule of thumb:
  • use class if there is at least one non-public member
  • use class if there is an invariant, struct if the members can vary indepently