std::remove_all_extents(3)

NAME
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.
   If the program adds specializations for std::remove_all_extents, 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_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 info(const A&)
 {
     typedef typename std::remove_all_extents<A>::type Type;
     std::cout << "underlying type: " << typeid(Type).name() << '\n';
 }
 int main()
 {
     float a0;
     float a1[1][2][3];
     float a2[1][1][1][1][2];
     float* a3;
     int a4[3][2];
     double a5[2][3];
     struct X { int m; } x0[3][3];
     info(a0);
     info(a1);
     info(a2);
     info(a3);
     info(a4);
     info(a5);
     info(x0);
 }

Possible output:
 underlying type: float
 underlying type: float
 underlying type: float
 underlying type: float*
 underlying type: int
 underlying type: double
 underlying type: main::X

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_extent removes one extent from the given array type
   (C++11) (class template)