friend functions c++

In object-oriented programming, 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 access if the data was private.

Example

#include <iostream>

class B
{
private:
	friend void privatePrint()
	{
		std::cout << "friend functions" << std::endl;
	}
};

class A
{
public:
	A()
	{
		// no need to access private part with public members of B
		privatePrint();  // direct calling
	}
};

int main()
{
	A a;
	getchar();
	return 0;
}

Output :

friend functions