Std::remove_all_extents (3) Linux Manual Page

std::remove_all_extents – std::remove_all_extents

Synopsis

Defined in header<type_traits>

    template <class T>
    (since C++ 11)

        struct remove_all_extents;

If T is a multidimensional array of some type X, provides the member typedef type equal to X, otherwise type is T.

Member types

Name Definition
type the type of the element of T

Helper types

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

Possible implementation

template<class T>
struct remove_all_extents { typedef T type;};

  template<class T>
  struct remove_all_extents<T[]> {
      typedef typename remove_all_extents<T>::type type;
  };

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

Example

// Run this code

#include <iostream>

#include <type_traits>

#include <typeinfo>
template <class A>

void foo(const A &)

{
    typedef typename std::remove_all_extents<A>::type Type;
    std::cout << "underlying type: " << typeid(Type).name() << '\n';
}
int main()

{
    float a1[1][2][3];
    int a2[3][2];
    float a3[1][1][1][1][2];
    double a4[2][3];
    foo(a1);
    foo(a2);
    foo(a3);
    foo(a4);
}

Possible output:

  underlying type: f
  underlying type: i
  underlying type: f
  underlying type: d

std::remove_all_extents (3) Linux Manual Page