std::remove_extent
From cppreference.com
Defined in header <type_traits> | ||
template<class T > struct remove_extent; | (since C++11) | |
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.
Contents |
[edit]Member types
| Name | Definition |
type | the type of the element of T |
[edit]Helper types
template<class T > using remove_extent_t =typename remove_extent<T>::type; | (since C++14) | |
[edit]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;}; |
[edit]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
[edit]See also
(C++11) | checks if a type is an array type (class template) |
(C++11) | obtains the number of dimensions of an array type (class template) |
(C++11) | obtains the size of an array type along a specified dimension (class template) |
(C++11) | removes all extents from the given array type (class template) |
