11/23/05

Classes:


Classes have a public part and a private part.

The public part typically includes "member functions"

The private part typically includes "data members".


A class defintion is similar to a struct defintion
but it includes two important ideas:


*  information hiding

      The private parts of your class are only
      available to member functions.   Users of the class
      cannot directly touch or read the private data members.

*  encapsulation

      Data members AND the functions all live inside the
      same "construct" (i.e. inside the class definition).

class ChristmasList_C
{

  public:
     ChristmasList_C (const char *  const theStoreName, 
                      const char * const anItemName,
		      const double thePrice,
		      const int numItems);
     void print();

     double getPrice();
     void setPrice(const double newPrice);

     int getNumItems();
     void setNumItems(const int newNumItems);


  private:
     char *storeName;
     char *itemName;
     double price;
     int numberOfItems;


}

 
Together with two other ideas:

* inheritance

* polymorphism

These four concepts make up what is known 
as Object Oriented Programming.

 


Comparison of a struct definition with
a class definition:

// struct Receiver_S
// {
//   char *name; // stuff on heap
//   char *team; // stuff on heap
//   int catches; 
//   double YAC; // yards after catch
// };


class Receiver_C
{

 public:
  Receiver_C(char *aName, char *aTeam, 
	     int howManyCatches, double theYACValue);
  int getCatches();
  void setCatches(int howManyCatches);
  void print();

 private:

   char *name; // stuff on heap
   char *team; // stuff on heap
   int catches; 
   double YAC; // yards after catch

};