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std::rank

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Revision as of 14:13, 2 November 2012 by P12bot (Talk | contribs)

 
 
 
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Template:ddcl list begin <tr class="t-dsc-header">

<td>
Defined in header <type_traits>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td >
template< class T >
struct rank;
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> Template:ddcl list end

If T is an array type, provides the member constant value equal to the number of dimensions of the array. For any other type, value is 0.

Contents

Inherited from std::integral_constant

Member constants

value
[static]
the number of dimensions of T or zero
(public static member constant)

Member functions

operator std::size_t
converts the object to std::size_t, returns value
(public member function)

Member types

Type Definition
value_type std::size_t
type std::integral_constant<std::size_t, value>

Possible implementation

template<class T>
struct rank : std::integral_constant<std::size_t, 0> {};
 
template<class T>
struct rank<T[]> : public std::integral_constant<std::size_t, rank<T>::value + 1> {};
 
template<class T, size_t N>
struct rank<T[N]> : public std::integral_constant<std::size_t, rank<T>::value + 1> {};

Example

#include <iostream>
#include <type_traits>
 
int main()
{
    std::cout << std::rank<int[1][2][3]>::value << '\n';
    std::cout << std::rank<int[][2][3][4]>::value << '\n';
    std::cout << std::rank<int>::value << '\n';
}

Output:

3
4
0

See also

(C++11)
checks if a type is an array type
(class template) [edit]
(C++11)
obtains the size of an array type along a specified dimension
(class template) [edit]
removes one extent from the given array type
(class template) [edit]
removes all extents from the given array type
(class template) [edit]