TITLE: Myth - C++ is a superset of ANSI C


RESPONSE: bs@research.att.com (Bjarne Stroustrup), 8 Jun 95

Here is the complete claim as found in ``The C++ Programming Language
(2nd Edition)'' Addison-Wesley. ISBN 0-201-53992-6. Appendix B, pg 626-627:

	C++ is based on C (K&R78) and adopts most of the changes specified
	by the ANSI C standard. Converting programs among C++, K&R C, and
	ANSI C may be subject to vicissitudes of expression evaluation.
	All differences between \*C and ANSI C can be diagnosed by a compiler.
	With the following three exceptions, programs that are both C++ and
	ANSI C have the same meaning in both languages:

	In C, sizeof('a') equals sizeof(int); in C++, it equals sizeof(char).

	In C, given

		enum e { A };

	sizeof(A) equals sizeof(int) ; in C++, it equals sizeof(e), which need
	not equal sizeof(int).

	A structure name declared in an inner scope can hide the name of an
	object, function, enumerator, or type in an outer scope. For example,

		int x[99];
		void f()
		{
		    struct x { int a; };
		    sizeof(x);  /* size of the array in C */
		                /* size of the struct in C++ */
		}

The other quote mentioned in this thread is found of page 6:

	Knowing C is not a prerequisite for learning C++. Programming in C
	encourages many techniques and tricks rendered unnecessary by
	C++ language features. For example, explicit type conversion,
	``casting,'' is less frequently needed in C++ than it is in C
	(see also the ``Note to C programmers'' below). However, *good*
	C programs tend to be \*C programs. For example, note that every
	program in Kernighan and Ritchie: The C Programming Language
	(2nd Edition)[8] is a C++ program.

There is also a more detailed discussion of the C/C++ compatibility issues
in ``The Design and Evolution of C++'' Addison Wesley, ISBN 0-201-54330-3.