utils/google-benchmark/src/arraysize.h

#ifndef BENCHMARK_ARRAYSIZE_H_
#define BENCHMARK_ARRAYSIZE_H_

#include "internal_macros.h"

namespace benchmark {
namespace internal {
// The arraysize(arr) macro returns the # of elements in an array arr.
// The expression is a compile-time constant, and therefore can be
// used in defining new arrays, for example.  If you use arraysize on
// a pointer by mistake, you will get a compile-time error.
//

// This template function declaration is used in defining arraysize.
// Note that the function doesn't need an implementation, as we only
// use its type.
template <typename T, size_t N>
char (&ArraySizeHelper(T (&array)[N]))[N];

// That gcc wants both of these prototypes seems mysterious. VC, for
// its part, can't decide which to use (another mystery). Matching of
// template overloads: the final frontier.
#ifndef COMPILER_MSVC
template <typename T, size_t N>
char (&ArraySizeHelper(const T (&array)[N]))[N];
#endif

#define arraysize(array) (sizeof(::benchmark::internal::ArraySizeHelper(array)))

}  // end namespace internal
}  // end namespace benchmark

#endif  // BENCHMARK_ARRAYSIZE_H_