W3cubDocs

/C++

std::is_floating_point

Defined in header `<type_traits>`
template< class T > struct is_floating_point;		(since C++11)

Checks whether T is a floating-point type. Provides the member constant value which is equal to true, if T is the type float, double, long double, or any extended floating-point types (std::float16_t, std::float32_t, std::float64_t, std::float128_t, or std::bfloat16_t) (since C++23), including any cv-qualified variants. Otherwise, value is equal to false.

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

Template parameters

a type to check

Helper variable template

template< class T >
inline constexpr bool is_floating_point_v = is_floating_point<T>::value;

(since C++17)

Inherited from std::integral_constant

Member constants

value

[static]

true if T is a floating-point type (possibly cv-qualified), 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_floating_point
     : std::integral_constant<
         bool,
         // Note: standard floating-point types
         std::is_same<float, typename std::remove_cv<T>::type>::value
         || std::is_same<double, typename std::remove_cv<T>::type>::value
         || std::is_same<long double, typename std::remove_cv<T>::type>::value
         // Note: extended floating-point types (C++23, if supported)
         || std::is_same<std::float16_t, typename std::remove_cv<T>::type>::value
         || std::is_same<std::float32_t, typename std::remove_cv<T>::type>::value
         || std::is_same<std::float64_t, typename std::remove_cv<T>::type>::value
         || std::is_same<std::float128_t, typename std::remove_cv<T>::type>::value
         || std::is_same<std::bfloat16_t, typename std::remove_cv<T>::type>::value
     > {};

Example

#include <iostream>
#include <type_traits>
 
class A {};
 
int main() 
{
    std::cout << std::boolalpha;
    std::cout << "      A: " << std::is_floating_point<A>::value << '\n';
    std::cout << "  float: " << std::is_floating_point<float>::value << '\n';
    std::cout << " float&: " << std::is_floating_point<float&>::value << '\n';
    std::cout << " double: " << std::is_floating_point<double>::value << '\n';
    std::cout << "double&: " << std::is_floating_point<double&>::value << '\n';
    std::cout << "    int: " << std::is_floating_point<int>::value << '\n';
}

Output:

      A: false
  float: true
 float&: false
 double: true
double&: false
    int: false

is_iec559 [static]	identifies the IEC 559/IEEE 754 floating-point types (public static member constant of `std::numeric_limits<T>`)
is_integral (C++11)	checks if a type is an integral type (class template)
is_arithmetic (C++11)	checks if a type is an arithmetic type (class template)
floating_point (C++20)	specifies that a type is a floating-point type (concept)