Friend function Remember that a member which is not public (Private and protected ) can not be accessed from outside the class. Three are some situations where you may need to access these. Keyword friend is used for this. A friend functions and classes can access all members of a class. This concept is controversial. People say friend concept violates data encapsulation A friend function is a non-member function but still can access all the members of a class including private members. Such a function is declared within class body with the prefix "friend" class Number { int num; public: Number( int m){ /*code*/ } friend void printNum(Number ob); /*friend function*/ }; void printNum (Number obj) { cout << obj.num << "endl" ; } printNum() is not member of class Number . But it can still access all members including private members, because it is a friend. Friend class An object of a friend c...