std::is_floating_point(3)

NAME
std::is_floating_point - std::is_floating_point

Synopsis
   Defined in header <type_traits>
   template< class T > (since C++11)
   struct is_floating_point;
   std::is_floating_point is a UnaryTypeTrait.
   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.
   If the program adds specializations for std::is_floating_point or
   std::is_floating_point_v, the behavior is undefined.

Template parameters
   T - a type to check
   Helper variable template
   template< class T >
   inline constexpr bool is_floating_point_v = (since C++17)
   is_floating_point<T>::value; Inherited from std::integral_constant

Member constants
   value true if T is a floating-point type (possibly cv-qualified), 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
   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
// Run this code
 #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

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