   Creating Classes from Base classes
  I thought I had a grip on classes in reference to the header and executable code .cpp files.  I was understanding that one held the declaration and one contained the actual code.However, in getting into creating classes off of base classes, that I was running into errors such as:error C2504: 'Class : base class undefinedThe Help file states this error says it is declared by not defined.  Attempts to see where I must not be referencing it using a #include directive, isn't taking care of the problem.Therefore, I was hoping to find out if someone knew a simple way to explain who I should view the difference between a .h and .cpp file and what the correct way to append a new .cpp file for a new class (i.e. adding a class to an existing project)  Should I create a .h file as well, or just a .cpp file and how to reference it corretly so I am not getting the C2504 that it isn't defined?   
  First, show your code. It's easier for people to point out what you're doing wrong when you show what you're doing.Second:// base.hclass Base{  // blah};// base.cpp#include <base.h>Base::<blah>...// derived.hclass Derived : public Base{  // bleh};// derived.cpp#include <derived.h>Derived::<bleh>...