include/array_length.h

   1 /* The array_length and array_end macros.
   2    Copyright (C) 2017-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _ARRAY_LENGTH_H
  20 #define _ARRAY_LENGTH_H
  21
  22 /* array_length (VAR) is the number of elements in the array VAR.  VAR
  23    must evaluate to an array, not a pointer.  */
  24 #define array_length(var)                                               \
  25   __extension__ ({                                                      \
  26     _Static_assert (!__builtin_types_compatible_p                       \
  27                     (__typeof (var), __typeof (&(var)[0])),             \
  28                     "argument must be an array");                       \
  29     sizeof (var) / sizeof ((var)[0]);                                   \
  30   })
  31
  32 /* array_end (VAR) is a pointer one past the end of the array VAR.
  33    VAR must evaluate to an array, not a pointer.  */
  34 #define array_end(var) (&(var)[array_length (var)])
  35
  36 #endif /* _ARRAY_LENGTH_H */