Namespaces
Variants
Views
Actions

std::rank

From cppreference.com
< cpp‎ | types
 
 
 
Type support
Basic types
Fundamental types
Fixed width integer types (C++11)
Numeric limits
C numeric limits interface
Runtime type information
Type traits
Primary type categories
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Type properties
(C++11)
(C++11)
(C++11)
(C++14)
Supported operations
Relationships and property queries
(C++11)
(C++11)
rank
(C++11)
(C++11)
Type modifications
(C++11)(C++11)(C++11)
Type transformations
(C++11)
(C++11)
(C++11)
Type trait constants
 
Defined in header <type_traits>
template< class T >
struct rank;
(since C++11)

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>

[edit] 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> {};

[edit] 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

[edit] 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]