6. Classes, Constructors & inline functions

21/02/23

new & delete

• Same kind of problems occur with new and delete with malloc() and free()

Classes and structs

• In C++ you can add functions to structs, use inheritance etc
• Do not treat them like C items
• Implementing some of these features may require that some hidden data is created
• Only thing difference is encapsulation, struct is public, class is private
• Good C++ practises
  • Data only and no member function: use a struct. You get the guarantees about size and positions of member data that you get in a C struct
  • If you add member functions then use a class
• Data and methods in class are either private or public
• Interface methods can be:
  • Mutators - Change the 'state' of the object
  • Accessors - Only query values, no changes

Constructors and Destructors

• Constructor - Called when an object is created
  • Created on the stack, when new is used
• Destructor - Called when an object is destroyed
  • When objects on stack are destroyed. When delete is used to destroy an object
• malloc and free do not create objects

Default Constructor

• Constructor which can be called with no parameters or has default values for all parameters
• Used whenever no parameters are specified

Initialisation lists are used a LOT in C++

Inline functions & Member functions and data

• Act exactly line normal function but no function call is made
• Useful for small fast one time functions