A.2.4 Keywords

The following identifiers are reserved for the use as keywords, and may not be used otherwise:

     auto          double      int          struct      break         else        long         switch      case          enum        register     typedef      char          extern      return       union      const         float       short        unsigned      continue      for         signed       void      default       goto        sizeof       volatile      do            if          static       while Some implementations also reserve the words fortran and asm. The keywords const, signed, and volatile are new with the ANSI standard; enum and void are new since the first edition, but in common use; entry, formerly reserved but never used, is no longer reserved