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std::remove_all_extents

Defined in header <type_traits>
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template< class T >
struct remove_all_extents;
 (since C++11)

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

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

Possible implementation

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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

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#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);
}

Output:

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

See also

(C++11)
 checks if a type is an array type
(class template)
(C++11)
 obtains the number of dimensions of an array type
(class template)
(C++11)
 obtains the size of an array type along a specified dimension
(class template)
(C++11)
 removes one extent from the given array type
(class template)
doc_CPP
doc_CPP
2025-01-10 15:47:30
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