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Encapsulation

• Classes are broken into public and private sections.
• The data items are defined in the private sections of the class definition.

  class Product
  {
  public:
     Product();
     void read();
     bool is_better_than(Product b) const;
     void print() const;
  private:
     string name;
     double price;
     int score;
  };
  

• Only constructors and member functions can access private data.
• Hiding data is called encapsulation.
• Encapsulation forces indirect access to the data, guaranteeing that it cannot accidentally be put in an incorrect state.
• Example:

  Time liftoff(19, 30, 0);
  /* liftoff is delayed by six hours */
  /* won't compile, but suppose it did */
  liftoff.hours = liftoff.hours + 6;
  

  Does this mean liftoff is at 25:30:00?

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