std::numeric_limits::is_modulo

From Cppreference


static const bool is_modulo		(pre-C++11 version)

static constexpr bool is_modulo		(C++11 version)

The value of std::numeric_limits<T>::is_modulo is true for all arithmetic types T that handle overflows with modulo arithmetic, that is, if the result of addition, subtraction, multiplication, or division of this type would fall outside the range [min(), max()], the value returned by such operation differs from the expected value by a multiple of max()-min()+1.

[edit] Standard specializations


`T`	value of std::numeric_limits<T>::is_modulo

/* non-specialized */	false

bool	false

char	true

signed char	true

unsigned char	true

wchar_t	true

char16_t	true

char32_t	true

short	true

unsigned short	true

int	true

unsigned int	true

long	true

unsigned long	true

long long	true

unsigned long long	true

float	false

double	false

long double	false

[edit] Example

Demonstrates the behavior of modulo types

#include <iostream>
#include <type_traits>
#include <limits>
 
template<typename T>
typename std::enable_if<std::numeric_limits<T>::is_modulo>::type
check_overflow()
{
    std::cout << "\nmax value is " << std::numeric_limits<T>::max() << '\n'
              << "min value is " << std::numeric_limits<T>::min() << '\n'
              << "max value + 1 is " << std::numeric_limits<T>::max()+1 << '\n';
}
 
int main()
{
    check_overflow<int>();
    check_overflow<unsigned long>();
    // check_overflow<float>(); // compile-time error, not a modulo type
}

Output:

max value is 2147483647
min value is -2147483648
max value + 1 is -2147483648
 
max value is 18446744073709551615
min value is 0
max value + 1 is 0

[edit] See also

is_integer

identifies integer types
(public static member constant)

is_iec559

identifies the IEC 559/IEEE 754 floating-point types
(public static member constant)

is_exact

identifies exact types
(public static member constant)