I have a class (CWindowedDisplay) that is derived from an abstract base class (CDisplay). However, when I create an instance of CWindowedDisplay (CDisplay *gfx; gfx= new CWindowedDisplay()), the constructor for CWindowedDisplay isn''t called. I''ve looked through the C++ documentation, and I couldn''t find anything that would solve my problem. Could somebody please give me a clue? Thanks!

That''s strange. How do you know that the base constructor is not called? Have you tried something like

  class base{        public:        base()        {   		//Write to a log or display message        }};class derived : public base{        public:        derived()        {		//Write to a log or display message         }};  

Then check you log file. If it still doesn''t work, post a snippet of the base and derived constructors.


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Andrew

My guess is that it called the default constructor. If you want new CWindowedDisplay() to call your constructor then you have to define one taking no parameters or one with defaults for all the parameters. Remember you can overload functions so func(int) isn''t the same as func(void).

I think the constructor may need to be virtual in the base class for that code to work

There are no such thing as virtual constructors. But I think LilBudyWizer is right, make sure your constructor, CWindowedDisplay(), takes no arguments, or alternativly write CDisplay *gfx = new CWindowedDisplay(argument1, argument2, ...).

Edited by - fredizzimo on November 13, 2000 12:17:29 AM