What prevents C++ from being a strict superset of C? [duplicate]

Question

Possible Duplicate:
“C subset of C++” -> Where not ? examples ?

I'm aware that C++ is not a strict superset of C. What language features prevent C++ from being a superset of C?

Answer 1

The elephant in the room: the following is valid C but not valid C++.

int typename = 1; 

Substitute your favorite C++ reserved word.

Answer 2

C++ also does not support variable-length arrays, where:

int array[n]; 

is valid in C, but not C++. A C++ version of the above would be:

int *array = new int[n];   ... delete [] array;