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1 | [/ |
2 | Copyright 2007 John Maddock. | |
3 | Distributed under the Boost Software License, Version 1.0. | |
4 | (See accompanying file LICENSE_1_0.txt or copy at | |
5 | http://www.boost.org/LICENSE_1_0.txt). | |
6 | ] | |
7 | ||
8 | [section:extent extent] | |
9 | template <class T, std::size_t N = 0> | |
10 | struct extent : public __integral_constant<std::size_t, EXTENT(T,N)> {}; | |
11 | ||
12 | __inherit Class template extent inherits from `__integral_constant<std::size_t, EXTENT(T,N)>`, | |
13 | where `EXTENT(T,N)` is the number of elements in the N'th array dimension of type `T`. | |
14 | ||
15 | If `T` is not a (built-in) array type, or if `N > __rank<T>::value`, or if the N'th array bound | |
16 | is incomplete, then `EXTENT(T,N)` is zero. | |
17 | ||
18 | __header ` #include <boost/type_traits/extent.hpp>` or ` #include <boost/type_traits.hpp>` | |
19 | ||
20 | __examples | |
21 | ||
22 | [:`extent<int[1]>` inherits from `__integral_constant<std::size_t, 1>`.] | |
23 | ||
24 | [:`extent<double[2][3][4], 0>::type` is the type `__integral_constant<std::size_t, 2>`.] | |
25 | ||
26 | [:`extent<double[2][3][4], 1>::type` is the type `__integral_constant<std::size_t, 3>`.] | |
27 | ||
28 | [:`extent<double[2][3][4], 2>::type` is the type `__integral_constant<std::size_t, 4>`.] | |
29 | ||
30 | [:`extent<int[4]>::value` is an integral constant | |
31 | expression that evaluates to /4/.] | |
32 | ||
33 | [:`extent<int[][2]>::value` is an integral constant | |
34 | expression that evaluates to /0/.] | |
35 | ||
36 | [:`extent<int[][2], 1>::value` is an integral constant | |
37 | expression that evaluates to /2/.] | |
38 | ||
39 | [:`extent<int*>::value` is an integral constant | |
40 | expression that evaluates to /0/.] | |
41 | ||
42 | [:`extent<boost::array<int, 3> >::value` is an integral constant | |
43 | expression that evaluates to /0/: `boost::array` is a class type and [*not an array type]!] | |
44 | ||
45 | [:`extent<T>::value_type` is the type `std::size_t`.] | |
46 | ||
47 | [all_compilers] | |
48 | ||
49 | [endsect] | |
50 |