how to call derived function using base class object

Question

class Parent
{
    public int GetNo()
    {
        return 1;
    }
}

class Child : Parent
{        
    public Child()
    {

    }

    public int GetNo()
    {           


        

Answer 1

I have just come here so i could find a solution that doesn't use casts, but since i didn't find it here is one.

Maybe it can be of help for someone.

abstract class Parent
{
    public int GetNo()
    {
        return GetNoImpl();
    }

    protected abstract int GetNoImpl();

}

class Child : Parent
{        
    public Child()
    {

    }

    protected override int GetNoImpl();
    {                       
        return 2;
    }
}

Parent p = new Child();
p.GetNo();

Note: the parent class is abstract.