error #20: identifier "class" is undefined

I used the built in option(when you right-click your project, new, class), that makes a class.  It automatically fills out a class with a xxxx.h and xxxx.cpp.  When i include these files into a xxxx.c file i get this error "error #20: identifier "class" is undefined".  Is there a compatibility issue because of the two different file types?  How can I make this work?  What can I do to fix this, or is there another means to make a class in C?  I'm using CCS 6.1 btw.