public:
The most open level of data hiding,
anything that is public is available to all derived classes of a base class,
and the public variables and data for each object of both the base and derived
class is accessible by code outside the class. Functions marked public are
generally those the class uses to give information to and take information from
the outside world; they are typically the interface with the class. The rest of
the class should be hidden from the user (This hidden nature and the highly
focused nature of classes is known collectively as encapsulation). The syntax
for public is:
public:
Everything following is public until
the end of the class or another data hiding keyword is used.
protected:
Variables and functions marked
protected are inherited by derived classes; however, these derived classes hide
the data from code outside of any instance of the object. Keep in mind, even if
you have another object of the same type as your first object, the second
object cannot access a protected variable in the first object. Instead, the
second object will have its own variable with the same name - but not
necessarily the same data. Protected is a useful level of protection for
important aspects to a class that must be passed on without allowing it to be
accessed. The syntax is the same as that of public. specifically,
protected:
private:
Private is the highest level of
data-hiding. Not only are the functions and variables marked private not
accessible by code outside the specific object in which that data appears, but
private variables and functions are not inherited. The level of data protection
afforded by protected is generally more flexible than that of the private
level. Of course, there is a certain joy in protecting your data with the
keyword private. The syntax remains the same.
private:
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