std:: is_array

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C++
Metaprogramming library
Type traits
Type categories
(C++11)
(C++14)
is_array
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
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(C++11)
(C++11)
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(C++11) (deprecated in C++26)
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(C++11) ( until C++20* )
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(C++11) (deprecated in C++23)
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(C++11)
(C++11)
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(C++11)
(C++11) ( until C++20* ) (C++17)
(C++20)
Compile-time rational arithmetic
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(C++14)
Defined in header <type_traits>
template < class T >
struct is_array ;
(since C++11)

std::is_array is a UnaryTypeTrait .

Checks whether T is an array type. Provides the member constant value which is equal to true , if T is an array type. Otherwise, value is equal to false .

If the program adds specializations for std::is_array or std::is_array_v , the behavior is undefined.

Template parameters

T - a type to check

Helper variable template

template < class T >
constexpr bool is_array_v = is_array < T > :: value ;
(since C++17)

Inherited from std:: integral_constant

Member constants

value
[static]
true if T is an array type, false otherwise
(public static member constant)

Member functions

operator bool
converts the object to bool , returns value
(public member function)
operator()
(C++14)
returns value
(public member function)

Member types

Type Definition
value_type bool
type std:: integral_constant < bool , value >

Possible implementation 

template<class T>
struct is_array : std::false_type {};
 
template<class T>
struct is_array<T[]> : std::true_type {};
 
template<class T, std::size_t N>
struct is_array<T[N]> : std::true_type {};

Example

Run this code 
#include <array>
#include <type_traits>
 
class A {};
static_assert(std::is_array<A>::value == false);
static_assert(std::is_array<A[]>::value == true);
static_assert(std::is_array<A[3]>::value == true);
 
static_assert(std::is_array<float>::value == false);
static_assert(std::is_array<int>::value == false);
static_assert(std::is_array<int[]>::value == true);
static_assert(std::is_array<int[3]>::value == true);
static_assert(std::is_array<std::array<int, 3>>::value == false);
 
int main() {}

See also

(C++20)
checks if a type is an array type of known bound
(class template)
(C++20)
checks if a type is an array type of unknown bound
(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)
(C++11)
removes all extents from the given array type
(class template)
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