This is the feature which makes C++ different from other
language approach. A class is similar to a structure but the only difference is
that class can contain member functions along with variables.
In class there are three
types of scope possible .they are private, public and the protected scope.
Private and public are mostly used but protected is mostly
used in inheritance and in other cases it has same scope as a private
member.
Public scope means a member declared under public section
can be accessed from any part of the program irrespective of the function in
which it is called and which all objects use it.
Private scope means a member declared under the private
section cannot be accessed from any were in the program but can only be
accessed by the member functions of the class itself.
So in a structure all the members have a public scope but
in class they can have any of the three scope. By
default the members of a class are private.
Syntax:
class class name{
public:
Member functions and variables;
private:
Member functions and variables;
protected:
Member functions and variables;
}
Here no semicolon is required after the class declaration .
The functions declared under the class are known as
member functions .the idea of using private is that any other function can use
or modify the private data of the class. Their are
only a few functions which have the permission to access these members.
class student{
int name;
char div;
void read_data();
} //member
function
Member functions are
functions which belong to the
class, and can thus access all of its members -- public, private and protected
-- without any restrictions.
Constant member functions are the functions which
can not modify the objects in the class the const keyword is used after the closing parenthesis of the
function declaration.
void add( ) const{
Statements ;
}
You cannot
modify the members of an object in a const member function, but they are the
only member function you can call on a constant object.
