The copy constructor is a constructor which creates an object by initializing it with an object of the same class, which has been created previously. The copy constructor is used to: Initialize one object from another of the same type. Copy an object to pass it as an argument to a function.
a friend function that is a “friend” of a given class is allowed access to private and protected data in that class that it would not normally be able to as if the data was public . Normally, a function that is defined outside of a class cannot access such information.
An existing class that is “parent” of a new class is called a base class. New class that inherits properties of the base class is called a derived class. Inheritance is a technique of code reuse. It also provides possibility to extend existing classes by creating derived classes.
An inline function is a function in which body is inserted in the place of its call. These functions can be compared with Macros. Inline functions are used to improve performance of the application. However, many inline functions can lead your program to grow up in size. That is why often only small functions are declared as inline
