NAME¶

std::remove_extent - std::remove_extent

Synopsis¶

Defined in header <type_traits>
template< class T > (since C++11)
struct remove_extent;

If T is an array of some type X, provides the member typedef type equal to X,
otherwise type is T. Note that if T is a multidimensional array, only the first
dimension is removed.

If the program adds specializations for std::remove_extent, the behavior is
undefined.

Member types¶

Name Definition
type the type of the element of T

Helper types¶

template< class T > (since C++14)
using remove_extent_t = typename remove_extent<T>::type;

Possible implementation¶

template<class T>
struct remove_extent { using type = T; };

template<class T>
struct remove_extent<T[]> { using type = T; };

template<class T, std::size_t N>
struct remove_extent<T[N]> { using type = T; };

Example¶

// Run this code

#include <algorithm>
#include <iostream>
#include <iterator>
#include <type_traits>

template<class A>
std::enable_if_t<std::rank_v<A> == 1>
print_1d(const A& a)
{
std::copy(a, a + std::extent_v<A>,
std::ostream_iterator<std::remove_extent_t<A>>(std::cout, " "));
std::cout << '\n';
}

int main()
{
int a[][3] = {{1, 2, 3}, {4, 5, 6}};
// print_1d(a); // compile-time error
print_1d(a[1]);
}

Output:¶

4 5 6

See also¶

is_array checks if a type is an array type
(C++11) (class template)
rank obtains the number of dimensions of an array type
(C++11) (class template)
extent obtains the size of an array type along a specified dimension
(C++11) (class template)
remove_all_extents removes all extents from the given array type
(C++11) (class template)