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[/
Copyright 2007 John Maddock.
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt).
]
[section:extent extent]
template <class T, std::size_t N = 0>
struct extent : public __integral_constant<std::size_t, EXTENT(T,N)> {};
__inherit Class template extent inherits from `__integral_constant<std::size_t, EXTENT(T,N)>`,
where `EXTENT(T,N)` is the number of elements in the N'th array dimension of type `T`.
If `T` is not a (built-in) array type, or if `N > __rank<T>::value`, or if the N'th array bound
is incomplete, then `EXTENT(T,N)` is zero.
__header ` #include <boost/type_traits/extent.hpp>` or ` #include <boost/type_traits.hpp>`
__examples
[:`extent<int[1]>` inherits from `__integral_constant<std::size_t, 1>`.]
[:`extent<double[2][3][4], 0>::type` is the type `__integral_constant<std::size_t, 2>`.]
[:`extent<double[2][3][4], 1>::type` is the type `__integral_constant<std::size_t, 3>`.]
[:`extent<double[2][3][4], 2>::type` is the type `__integral_constant<std::size_t, 4>`.]
[:`extent<int[4]>::value` is an integral constant
expression that evaluates to /4/.]
[:`extent<int[][2]>::value` is an integral constant
expression that evaluates to /0/.]
[:`extent<int[][2], 1>::value` is an integral constant
expression that evaluates to /2/.]
[:`extent<int*>::value` is an integral constant
expression that evaluates to /0/.]
[:`extent<boost::array<int, 3> >::value` is an integral constant
expression that evaluates to /0/: `boost::array` is a class type and [*not an array type]!]
[:`extent<T>::value_type` is the type `std::size_t`.]
[all_compilers]
[endsect]
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