OOPS - [C++ Static Members of Class]

♠ Posted by Unknown in CPP Language at 07:17

Static Class Members

A data members of a class can be qualified as static. A static member variable has certain special characteristics. These are :

1.     It is initialized to zero when the first object of its class is created. No other initialization is permitted.

2.     Only one copy of that member is created for the entire class and is shared by all the objects of that class, no matter how many objects are created.

3.     It is visible only within the class, but its lifetime is the entire program.

Static variables are normally used to maintain values common to the entire class. for example a static data member can be used as a counter that records the occurrences of all the objects.

Like static member variable, we can also have static member functions. A member function that is declared static has the following properties:

1.     A static function can have access to only other static members (function or variables) declared in the same class.

2.     A static member function can be called using the class name (instead of its objects) as follows:

                  Class_name :: function_name;

For Example:

#include<iostream.h>

#include<conio.h>

class StaticExa

{

      static int count;

 public:

      StaticExa()

      {

                  count++;

                  cout<<count<< " Object is Created...."<<endl;

      }

      static void display()

      {

                  cout<<"Total "<<count<<" Objects are Created...."<<endl;

      }

      ~StaticExa()

      {

                  cout<<count<<" Object is Destroyed...."<<endl;

                  count--;

      }

};

int StaticExa :: count;

void main()

{

 clrscr();

 StaticExa st[10];

 StaticExa :: display();

 getch();

}