< cpp‎ | types
Metaprogramming library
Type traits
Type categories
Type properties
(C++11)(until C++20)
(C++11)(deprecated in C++20)
Type trait constants
Supported operations
Relationships and property queries
Type modifications
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)

(C++11)(until C++20)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
Defined in header <type_traits>
template< class T >
struct is_integral;
(since C++11)

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, long long, or any implementation-defined extended integer types, including any signed, unsigned, and cv-qualified variants. Otherwise, value is equal to false.

The behavior of a program that adds specializations for is_integral or is_integral_v (since C++17) is undefined.


[edit] Template parameters

T - a type to check

[edit] Helper variable template

template< class T >
inline constexpr bool is_integral_v = is_integral<T>::value;
(since C++17)

Inherited from std::integral_constant

Member constants

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)
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 facilities
template< 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

#include <iostream>
#include <iomanip>
#include <type_traits>
class A {};
struct B { int x:4{2}; };
using BF = decltype(B::x); // bit-field's type
enum E : int {};
template <class T>
T f(T i)
    static_assert(std::is_integral<T>::value, "Integral required.");
    return i;
#define SHOW(...) \
    std::cout << std::setw(29) << #__VA_ARGS__ << " == " << __VA_ARGS__ << '\n'
int main()
    std::cout << std::boolalpha;
    SHOW( std::is_integral<A>::value );
    SHOW( std::is_integral_v<E> );
    SHOW( std::is_integral_v<float> );
    SHOW( std::is_integral_v<int*> );
    SHOW( std::is_integral_v<int> );
    SHOW( std::is_integral_v<const int> );
    SHOW( std::is_integral_v<bool> );
    SHOW( std::is_integral_v<char> );
    SHOW( std::is_integral_v<BF> );
    SHOW( f(123) );


   std::is_integral<A>::value == false
        std::is_integral_v<E> == false
    std::is_integral_v<float> == false
     std::is_integral_v<int*> == false
      std::is_integral_v<int> == true
std::is_integral_v<const int> == true
     std::is_integral_v<bool> == true
     std::is_integral_v<char> == true
       std::is_integral_v<BF> == true
                       f(123) == 123

[edit] See also

specifies that a type is an integral type
(concept) [edit]
identifies integer types
(public static member constant of std::numeric_limits<T>) [edit]
checks if a type is a floating-point type
(class template) [edit]
checks if a type is an arithmetic type
(class template) [edit]
checks if a type is an enumeration type
(class template) [edit]