Access
Control in Classes:
Now
before studying how to define class and its objects, let’s first quickly learn
what access specifiers are.
Access
specifiers in C++ class defines the access control rules. C++ has 3 new
keywords introduced, namely,
1.
Public
2.
Private
3.
Protected
These
access specifiers are used to set boundaries for availability of members of
class be it data members or member functions
Access
specifiers in the program, are followed by a colon. You can use either one, two
or all 3 specifiers in the same class to set different boundaries for different
class members. They change the boundary for all the declarations that follow
them.
Public:
Public,
means all the class members declared under public will be available to
everyone. The data members and member functions declared public can be accessed
by other classes too. Hence there are chances that they might change them. So
the key members must not be declared public.
class
PublicAccess
{
public:
// public access specifier
int x; // Data Member Declaration
void display(); // Member Function declaration
}
Private:
Private
keyword, means that no one can access the class members declared private
outside that class. If someone tries to access the private member, they will
get a compile time error. By default class variables and member functions are
private.
class
PrivateAccess
{
private:
// private access specifier
int x; // Data Member Declaration
void display(); // Member Function declaration
}
Protected:
Protected,
is the last access specifier, and it is similar to private, it makes class
member inaccessible outside the class. But they can be accessed by any subclass
of that class. (If class A is inherited by class B, then class B is subclass of
class A. We will learn this later.)
class
ProtectedAccess
{
protected:
// protected access specifier
int x; // Data Member Declaration
void display(); // Member Function declaration
}
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