C++ Programming - OOPS Concepts - Discussion

class Y
{
public:
Y();
};
class X
{
private:
void foo() {}
friend Y::Y();
};
Y::Y()
{
X x; x.foo();
}

As per 11.3 Friends [class.friend]


When a friend declaration refers to an overloaded name or operator, only the function specified by the parameter types becomes a friend. A member function of a class X can be a friend of a class Y.

[ Example:

class Y {
friend char* X::foo(int);
friend X::X(char); // constructors can be friends
friend X::~X(); // destructors can be friends
};

"end example ]

A friend is a function, but not a constructor.

Because Constructor has three types:

1. Default Constructor.
2. Parameterized Constructor.
3. Copy Constructor.

The friend is not a type of any constructor. Right? If not please explain in detail.

It's not a constructor.

Constructors are basically of 3 types:
1. Default Constructor (without arguments).
2. Parameterized Constructor (with arguments).
3. Copy Constructor.

It is a function called Friend Function.

Friend Function is used to access private members of two different classes for which it has been declared as a friend.

Note: There are main 3 types only.

1. Default.
2. Parameterless.
3. Parameterized.

Copy constructor is under Parameterized constructor.

A constructor can not be defined outside the class so Friend constructor can't be define.

We have a friend class and function, not any constructor.

Constructors are of three types:
* Default Constructor.
* Parametrized Constructor.
* Copy Constructor.