GeeksforGeeks » C/C++ Programming Questions

friend and inheritance in C++

(3 posts)

Tags:

  1. geek
    guest
    Posted 8 months ago #

    Why does the following program work? show() is not a friend of class B.

    #include<iostream>
using namespace std;

class A
{
protected:
    int x;
public:
    A() { x = 0; }
    friend void show();
};

class B: public A
{
public:
    B() : y (0) {}
private:
    int y;
};

void show()
{
    B b;
    cout << "The default value of A::x = " << b.x;
}

int main()
{
    show();
    return 0;
}

  2. geek
    guest
    Posted 8 months ago #

    Surprisingly, when I change the program to following, it fails in compilation.

    #include<iostream>
using namespace std;

class A
{
protected:
    int x;
public:
    A() { x = 0; }
    friend void show();
};

class B: public A
{
public:
    B() : y (0) {}
private:
    int y;
};

void show(B b)
{
    cout << "The default value of A::x = " << b.x;
}

int main()
{
    B b;
    show(b);
    return 0;
}

  3. Deepesh
    guest
    Posted 4 months ago #

    X is a member of class A and class A is a friend of show function


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