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Variants

std::numeric_limits<T>:: is_integer

From cppreference.net
C++
Utilities library
Type support
std::numeric_limits
Static constants
numeric_limits::is_integer
(C++11)
Static member functions
(C++11)
Helper types
static const bool is_integer ;
(until C++11)
static constexpr bool is_integer ;
(since C++11)

The value of std:: numeric_limits < T > :: is_integer is true for all integer arithmetic types T and false otherwise. This constant is meaningful for all specializations.

Standard specializations

T value of std:: numeric_limits < T > :: is_integer
/* non-specialized */ false
bool true
char true
signed char true
unsigned char true
wchar_t true
char8_t (since C++20) true
char16_t (since C++11) true
char32_t (since C++11) true
short true
unsigned short true
int true
unsigned int true
long true
unsigned long true
long long (since C++11) true
unsigned long long (since C++11) true
float false
double false
long double false

Example

Run this code 
#include <cstddef>
#include <cstdint>
#include <limits>
static_assert
(
        std::numeric_limits<bool>::is_integer
    &&  std::numeric_limits<std::size_t>::is_integer
    &&  std::numeric_limits<std::int32_t>::is_integer
    &&  std::numeric_limits<std::int64_t>::is_integer
    &&  std::numeric_limits<decltype(42)>::is_integer
    && !std::numeric_limits<int*>::is_integer
    && !std::numeric_limits<float>::is_integer
    && !std::numeric_limits<double>::is_integer
    && !std::numeric_limits<long double>::is_integer
    && !std::numeric_limits<decltype([](){})>::is_integer // P0315R4
);
int main() {}

See also

(C++11)
checks if a type is an integral type
(class template)
[static]
identifies signed types
(public static member constant)
[static]
identifies exact types
(public static member constant)
[static]
identifies types that represent a finite set of values
(public static member constant)