# std::is_integral

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< cpp‎ | types

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, long long, 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.

### Template parameters

T | - | a type to check

### Helper variable template

template< class T > constexpr bool 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>

### 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
        }> {};

### 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<const int> == 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() {}

### See also

integral (C++20) | specifies that a type is an integral type (concept)
is_integer [static] | identifies integer types (public static member constant of `std::numeric_limits<T>`)
is_floating_point (C++11) | checks if a type is a floating-point type (class template)
is_arithmetic (C++11) | checks if a type is an arithmetic type (class template)
is_enum (C++11) | checks if a type is an enumeration type (class template)

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