std::is_unbounded_array(3)

🌸 NAME 🌸

Okay so bestie, welcome to the std::is_unbounded_array(3) page from the C++ Standard Libary manual 💅. The NAME line is literally std::is_unbounded_array - std::is_unbounded_array — yes, she said it twice, and honestly? iconic.

✨ Synopsis ✨

Defined in header <type_traits>:

template< class T >              (since C++20)
struct is_unbounded_array;

std::is_unbounded_array is a UnaryTypeTrait.

She checks whether T is an arrays of unknown bound. Provides the member constant value which is equal to true, if T is an array type of unknown bound. Otherwise, value is equal to false.

⚠️ Heads up, bestie: if the program adds specializations for std::is_unbounded_array or std::is_unbounded_array_v, the behavior is undefined. That is a no-cap do-not-touch.

🧚 Template parameters 🧚

• T - a type to check

🎀 Helper variable template 🎀

template< class T >
inline constexpr bool is_unbounded_array_v =
(since C++20)
is_unbounded_array<T>::value;

Also: Inherited from std::integral_constant — slay.

💜 Member constants 💜

• value — true if T is an array type of unknown bound., false otherwise; [static] (public static member constant)

🫶 Member functions 🫶

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

🦋 Member types 🦋

• value_type — bool
• type — std::integral_constant<bool, value>

🛠 Possible implementation 🛠

template<class T>
struct is_unbounded_array: std::false_type {};

template<class T>
struct is_unbounded_array<T[]> : std::true_type {};

📝 Notes 📝

Feature-test macro table, but make it cute:

• Feature-test macro: __cpp_lib_bounded_array_traits
• Value: 201902L
• Std: (C++20)
• Feature: std::is_bounded_array, std::is_unbounded_array

💻 Example 💻

// Run this code

#include <type_traits>

class A {};

static_assert
(""
    && std::is_unbounded_array_v<A> == false
    && std::is_unbounded_array_v<A[]> == true
    && std::is_unbounded_array_v<A[3]> == false
    && std::is_unbounded_array_v<float> == false
    && std::is_unbounded_array_v<int> == false
    && std::is_unbounded_array_v<int[]> == true
    && std::is_unbounded_array_v<int[3]> == false
);

int main() {}

👀 See also 👀

• is_array — checks if a type is an array type (C++11) (class template)
• is_bounded_array — checks if a type is an array type of known bound (C++20) (class template)
• extent — obtains the size of an array type along a specified dimension (C++11) (class template)

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okay bye bestie 💖 this was the std::is_unbounded_array(3) page from http://cppreference.com, dated 2024.06.10 — mwah, go flex those type traits 🎀🦋