How do I find the length of an array?

Question

Is there a way to find how many values an array has? Detecting whether or not I\'ve reached the end of an array would also work.

Answer 1

As other's said you can use the sizeof(arr)/sizeof(*arr) but this will give you the wrong answer for pointer types that aren't arrays.

template
constexpr size_t size(T (&)[N]) { return N; }

This has the nice property of failing to compile for non array types (visual studio has _countof which does this). The constexpr makes this a compile time expression so it doesn't have any drawbacks over the macro (at least none I know of).

You can also consider using std::array from C++11 which exposes its length with no overhead over a native C array.

C++17 has std::size() in the header which does the same and works for STL containers too (thanks to @Jon C).