std::remove_extent

 

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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.

The behavior of a program that adds specializations for remove_extent is undefined.

Member types

Name	Definition
type	the type of the element of T

Helper types

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

Possible implementation

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

Example

Run this code

#include <iostream>
#include <iterator>
#include <algorithm>
#include <type_traits>
 
template<class A>
typename std::enable_if< std::rank<A>::value == 1 >::type
print_1d(const A& a)
{
    copy(a, a+std::extent<A>::value,
         std::ostream_iterator<typename std::remove_extent<A>::type>(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 (C++11)	checks if a type is an array type (class template)
rank (C++11)	obtains the number of dimensions of an array type (class template)
extent (C++11)	obtains the size of an array type along a specified dimension (class template)
remove_all_extents (C++11)	removes all extents from the given array type (class template)