In C++, there are eleven keywords which are simply alternate spellings
of operators normally written with punctuation. These keywords are
treated as such even in the preprocessor. They function as operators in
#if, and they cannot be defined as macros or poisoned. In C, you
can request that those keywords take their C++ meaning by including
iso646.h. That header defines each one as a normal object-like
macro expanding to the appropriate punctuator.
These are the named operators and their corresponding punctuators: