What does Friend class mean?

[Owen Fernandes]

Hello Guys,

I am new to the programming field. I have one question regarding the classes. I am not able to understand the friend class concept. I want to be aware about the What friend class in object oriented programming. It essential to know this as the class is the main part of the object oriented programming. I have referred lot's of books for this without any luck. I wonder if anyone let me know what is friend class in OOP. I am waiting for your reply.

[Praetor]

Hi,

Using friend class we can access the another class component and it is done by without creating that component as public. So it prevent the overhead which is created by calling the member function for getting private component. See following example in which a class 'Vqt' is 'friend class':

class Vq 
{

friend class Vqt;
int value;
...

}

[Katty]

Developing a friend class or a function enables the same function or class can access private members (methods, attributes, etc.) in class "host".This means that value stored in variables, and operations can be accessed easily with friend function.
Example:

class FJE {
private int bs;

public:
void display () {}

friend void modify (int Tz);
};

void modify (int im) (
c.private = i;
}

int main ()
{
Tz ttt;

modify (ttt, 8);

ttt.afficher ();

return 0;
}

[kelfro]

Friends can be either functions or other classes. A Friend class offers privileged access rights to other class. The developer of a class exercise in control theory and technology policy both on friends as member functions of class (if it was not the case, he should obtain permission from those who have written some friends when he wants to change his class). In short it is something that allows a class to offer privileged access rights to another class or function.

[Zecho]

Member functions and friend class have identical access rights (that is 100% guaranteed). The main difference is that a call to a friend class of the form f (x), then a call to a member function of the form xf (). The main disadvantage of using friend class is that they need an extra line of code to get a dynamic binding (dynamic binding). To use a virtual class, it is necessary that the friend class must calls a virtual member function. This is known as the idiom of the Virtual Friend Function.

[Reegan]

Hi friend,

Refer the following program code, Here I have declared class 'NKT' as friend class and which is called in class 'GBP':

class GBP
{
private:

//...

public:

//...

friend classNKT;
}