What additional data types does C++ add compared to C?

C++ adds bool (true/false) and wchar_t (a wide character) as built-in types.

In C these aren't built in:

• bool requires #include <stdbool.h> (added in C99)
• wchar_t lives in #include <wchar.h>

Gotcha: wchar_t's size is not fixed by the standard. It's commonly described as a 16-bit type (and is 2 bytes on Windows), but with g++ on Linux it is actually 4 bytes. If you need a guaranteed width, use char16_t/char32_t.

C++ also adds (beyond plain data types):

• References (int&)
• Classes and objects
• STL containers (vector, string, etc.)