std::is_integral
From cppreference.com
Defined in header <type_traits> | ||
template<class T > struct is_integral; | (since C++11) | |
std::is_integral is a UnaryTypeTrait.
Checks whether T is an integral type. Provides the member constant value which is equal to true, if T is the type bool, char, char8_t(since C++20), char16_t, char32_t, wchar_t, short, int, long, longlong, or any implementation-defined extended integer types, including any signed, unsigned, and cv-qualified variants. Otherwise, value is equal to false.
If the program adds specializations for std::is_integral or std::is_integral_v, the behavior is undefined.
Contents |
[edit]Template parameters
| T | - | a type to check |
[edit]Helper variable template
template<class T > constexprbool is_integral_v = is_integral<T>::value; | (since C++17) | |
Inherited from std::integral_constant
Member constants
value [static] | true if T is an integral 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> |
[edit]Possible implementation
// Note: this implementation uses C++20 facilitiestemplate<class T>struct is_integral :std::bool_constant< requires (T t, T* p, void(*f)(T))// T* parameter excludes reference types{reinterpret_cast<T>(t);// Exclude class types f(0);// Exclude enumeration types p + t;// Exclude everything not yet excluded but integral types}>{}; |
[edit]Example
Run this code
#include <type_traits> static_assert ( std::is_integral_v<float>==false&& std::is_integral_v<int*>==false&& std::is_integral_v<int>==true&& std::is_integral_v<constint>==true&& std::is_integral_v<bool>==true&& std::is_integral_v<char>==true); class A {}; static_assert(std::is_integral_v<A>==false); struct B {int x:4;}; static_assert(std::is_integral_v<B>==false);using BF = decltype(B::x);// bit-field's type static_assert(std::is_integral_v<BF>==true); enum E :int{}; static_assert(std::is_integral_v<E>==false); template<class T>constexpr T same(T i){ static_assert(std::is_integral<T>::value, "Integral required.");return i;} static_assert(same('"')==042); int main(){}
[edit]See also
(C++20) | specifies that a type is an integral type (concept) |
[static] | identifies integer types (public static member constant of std::numeric_limits<T>) |
(C++11) | checks if a type is a floating-point type (class template) |
(C++11) | checks if a type is an arithmetic type (class template) |
(C++11) | checks if a type is an enumeration type (class template) |
