These are words that are reserved in the C language.

auto             break            case             char
const            continue         default          do
double           else             enum             extern
float            for              goto             if
int              long             register         return
short            signed           sizeof           static
struct           switch           typedef          union
unsigned         void             volatile         while

In addition, these words are also reserved in the C++ language.

and              and_eq           asm              bitand
bitor            bool             catch            class
compl            const_cast       delete           dynamic_cast
explicit         export           false            friend
inline           mutable          namespace        new
not              not_eq           operator         or
or_eq            private          protected        public
reinterpret_cast static_cast      template         this
throw            true             try              typeid 
typename         using            virtual          wchar_t
xor              xor_eq