Question

I’m making my constructors a bit more strict by removing some of my empty constructors. I’m pretty new to inheritance, and was perplexed with the error that I got: Base Class Doesn’t Contain Parameterless Constructor. How can I make A2 inherit from A without there being an empty constructor in A. Also, for my own personal understanding, why is A2 requiring an empty constructor for A?

Class A{
    //No empty constructor for A
    //Blah blah blah...
}

Class A2 : A{
    //The error appears here
}

Answer 1

In class A2, you need to make sure that all your constructors call the base class constructor with parameters.

Otherwise, the compiler will assume you want to use the parameterless base class constructor to construct the A object on which your A2 object is based.

Example:

class A
{
    public A(int x, int y)
    {
        // do something
    }
}

class A2 : A
{
    public A2() : base(1, 5)
    {
        // do something
    }

    public A2(int x, int y) : base(x, y)
    {
        // do something
    }

    // This would not compile:
    public A2(int x, int y)
    {
        // the compiler will look for a constructor A(), which doesn't exist
    }
}