Found this on the FAQ board and it should probably be amended or removed, as it is misleading at best:
FAQ Difference between C, C++ and C#
C++ - a "better C" (Stroustrop, guy who made it). It is an extension of C. All good C programs are also C++ programs, but the reverse is not true. Contains elements that generally make large scale programming easier.
C and C++ may be related, but they are different languages with different standards and different design goals. And there are myriad "good C programs" that are not C++ programs.
A fun experiment would be to download any moderately sized C project from SourceForge and try to compile it with a C++ compiler.