Friend function

A friend function is a function that is not a member of a class, but has access to the private and protected members of the class. It can be declared as a friend within the class definition by using the friend keyword.

Here's an example:

class MyClass {
private:
    int x;
public:
    MyClass(int num) : x(num) {}

    // Declaring display() as a friend function
    friend void display(MyClass obj);
};

// Definition of display() outside the class
void display(MyClass obj) {
   cout << "The value of x is: " << obj.x << endl;
}

int main() {
   MyClass myObj(5);
   display(myObj);  // Calling the friend function

   return 0;
}

In this example, display() is declared as a friend function inside the MyClass definition. As such, it can directly access and print out the private member x without needing any getter or setter functions.

Friend functions are commonly used when we want certain non-member functions to have direct access to internal data members or functionality of a class.

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