lib/ccan/array_size/array_size.h

   1 #ifndef CCAN_ARRAY_SIZE_H
   2 #define CCAN_ARRAY_SIZE_H
   3 #include "config.h"
   4 #include <ccan/build_assert/build_assert.h>
   5
   6 /**
   7  * ARRAY_SIZE - get the number of elements in a visible array
   8  * @arr: the array whose size you want.
   9  *
  10  * This does not work on pointers, or arrays declared as [], or
  11  * function parameters.  With correct compiler support, such usage
  12  * will cause a build error (see build_assert).
  13  */
  14 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + _array_size_chk(arr))
  15
  16 #if HAVE_BUILTIN_TYPES_COMPATIBLE_P && HAVE_TYPEOF
  17 /* Two gcc extensions.
  18  * &a[0] degrades to a pointer: a different type from an array */
  19 #define _array_size_chk(arr)                                            \
  20         BUILD_ASSERT_OR_ZERO(!__builtin_types_compatible_p(typeof(arr), \
  21                                                         typeof(&(arr)[0])))
  22 #else
  23 #define _array_size_chk(arr) 0
  24 #endif
  25 #endif /* CCAN_ALIGNOF_H */