C++ - What is friend function?

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What is friend function?

As the name suggests, the function acts as a friend to a class. As a friend of a class, it can access its private and protected members. A friend function is not a member of the class. But it must be listed in the class definition.

Total Answers and Comments: 4

Last Update: June 12, 2009

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Submitted by: Arvind

Its the main feature of a class that private member data of a class can be accessed only by the class' member functions. But there is an exception , A class can allow non-member functions and other classes to access its own private data, by making them as friends.
class Test
{
private:
    int a;

public:
    void xyz( );
    friend void display(Test); //Friend of the class 'Test' , display() can access the                                              //private data members of the class
}

void display(Test x)
{
cout << x.a;// Class private data can be accessed.
}

Above answer was rated as good by the following members:
geeker2008, ozkan, the_ankit1987

April 12, 2006 02:06:42

paulson paul chambakottukudyil

RE: What is friend function? &nb...

A friend function is a non member function of a class that is declared as a friend using the keyword friend inside the class. By declaring a function as a friend all the access permissions are given to the function.

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August 29, 2007 01:23:05

Param01

RE: What is friend function? &nb...

A friend function is a non member function of a class that is declared as a friend using the keyword "friend" inside the class. By declaring a function as a friend all the access permissions are given to the function.

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October 12, 2007 00:51:25

Arvind

RE: What is friend function? &nb...

Its the main feature of a class that private member data of a class can be accessed only by the class' member functions. But there is an exception A class can allow non-member functions and other classes to access its own private data by making them as friends.
class Test
{
private:
int a;

public:
void xyz( );
friend void display(Test); //Friend of the class 'Test' display() can access the //private data members of the class
}

void display(Test x)
{
cout << x.a;// Class private data can be accessed.
}

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3 0

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June 12, 2009 08:29:11

gunjan.chandra

Member Since: April 2009 Contribution: 7

RE: What is friend function?

Friend function is used in OOP languages which allows a private or protected function to be accessed by a member outside a class.

Any function outside a Class can be given access to work with members inside a class by simply writing a keyword
friend before it thus making it friend of the member functions.

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