Question

I have a class as follows:

class base
{
    protected:
        int x;
        int y;
        int z;
    public:
        base(int x, int y, int z)
        {
            x = x;
            y = y;
            z = z;
        }
        virtual void show();
};

I derive a class from the above as:

class derived : protected base
{
    public:
        int a;
        int b;
        int c;
        derived(int a, int b, int x, int y, int z) : base(x, y, z) //initialising the base class members as well
        {
            cout<<a<<b<<x<<y<<z; //works fine
            a = a;
            b = b;
        }
        void show()
        {
            cout<<a<<b<<x<<y<<z; //show junk values            
        }
        //some data members and member functions
};

In main(), I use:

    derived d(1, 2, 3, 4, 5);

    d.show();

The data members appear to have legal values inside the constructor. However, when I use a similar function, i.e. with the same visibility mode, junk values seem to appear.

Answer 1

a = a;
b = b;

should be

this->a = a;
this->b = b;

or, even better, use an initializer list:

derived(int a, int b, int x, int y, int z) : a(a), b(b),  base(x,y,z) 
{
    cout<<a<<b<<x<<y<<z; //works fine
}

what you’re doing is self-assigning the parameter, so the members don’t get set.