Problems linking c++ class libraries

[Mark L. Wise]

Hello all!

I am relatively new to c++ and I have a question regarding linking class
libraries.

I have a "main line" program that calls a class out of a library (A) that I
built.  This class library also calls classes out of another library (B).
When I try to link I get an unresolved call to <the class name> class
(library B) that I call in library "A".

HOWEVER, If I include a "dummy" call in my "mainline" program to the class
in library "B", then the link from library "A" completes to library "B" and
the program runs.

Why do I have to include a reference call to the class in library "B" in my
mainline program to get it the linker to resolve the link?

Thanks in advance for any advice!!

Mark