member function of one class can be friend function of another class

[Tanushreeagr]

How to make a member function of one class , the friend function of another class:


class car
{
private:
int speed;

char color[20];

public:

void input()
{
cin >> color >> speed;
}

void display(car c)// Member function of Class car, which i want to make friend function for Class Scooter
{
cout << c.color << endl << c.speed;
}
};


class scooter
{

public:
int input_i()
{
cin >> color >> speed;
}
friend void car::display(scooter); // I am trying to make the member function display() of Class car , friend function for Class scooter.
};

void display(scooter s)
{
cout << s.color << s.speed;// compiler error color and speed undeclared.

}

// I want to make color and speed visible in Scooter class my making display function , friend function of class scooter.

void main()
{
car c1;
scooter s1;

c1.input();

s1.input_i();

c1.display(c1);

s1.display(s1);

}

[In the above program i want to make the member function display() of class Car , the friend function for class Scooter, so that class scooter can access private data members(speed and color) of class Car.]


But i think there's a mistake in above coding , so please help me how i could do this, as compiler error: nonexistent function 'car::display' specified as friend

THANKS.....

[VictorN]

M...
[ In the above program : friend void car::display(scooter); Is this the correct way to make member function of one class , friend function of another class.?]

1. please, use Code tags while posting code snippets.
2. Did you try to compile this code? What does compiler say you?

[Tanushreeagr]

1. please, use Code tags while posting code snippets.
2. Did you try to compile this code? What does compiler say you?

I have added necessary code.

[S_M_A]

No you haven't. The post still lacks code tags [code]Properly indented code here[/code]

[Peter_B]

I suspect that the correct way to solve your real problem (not the one stated here - that is just due to the way you are approaching this) is to have a base class (e.g. vehicle) which contains the speed and color fields, and the method display. Then derive car and scooter classes from this.

[Skizmo]

Please stop using the 'friend' keyword. Wipe it from your memory. As soon ans you need the 'friend' keyword, your design is wrong.

[Igor Vartanov]

As soon ans you need the 'friend' keyword, your design is wrong.

Untrue as any excessively categorical statement. An advice to use 'friend' as rare as possible would be more correct.