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.

The behavior of a program that adds specializations for remove_all_extents 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)