std::remove_extent (3) - Linux Manuals

std::remove_extent: std::remove_extent

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.

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 { 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