C++ is a language derived from C. The major change is the addition of classes and a mechanism for inheriting class objects into other classes. The design of C++ was guided by three principles: 1. The use of classes would not result in programs executing any more slowly than programs not using classes. 2. In order to make sure that the addition of classes did not cause other needed features to be omitted, C programs should run as a subset of C++ programs. 3. No run-time inefficiency should be added to the language.