Friend keyword is used for friend functions.
In C++ class has data member and member function. Data member declare private that cannot be accessed outside the class, means non-member function of class. But some time situation is arises, private data member need to access outside the class. That is done by friend function. A friend function is called non-member function, when we create friend function, we can access private member of class.
Graphics is one of the main feature of c++. By using Graphics we can draw any shape.#include<graphics.h> header files defines a number of graphics function like
Point…….simply a pair(x,y)representing a coordinate in the window
Circle…….defines by a point and a radius
Line………Two points one is starting point and other is the end point
Message…..Used to display in the graphics window.
Operator Overloading means overloading an operator.We can write function as normal but Function name is keyword(reserved keyword) "operator" with symbol(operator+).We can used this to overload the addition operator.
When we use same function name in both base class(parents class, super clas) and derived class
(child class, sub class), the function in base class is declared as virtual using the keyword virtual.
A virtual function, equated to zero(function name()=0) is called a pure virtual function.