std::numeric_limits<T>::is_exact

 

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numeric_limits
C numeric limits interface
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type_info type_index (C++11)	bad_typeid bad_cast

 

std::numeric_limits

Static constants

numeric_limits::is_specialized

numeric_limits::is_signed

numeric_limits::is_integer

numeric_limits::is_exact

numeric_limits::has_infinity

numeric_limits::has_quiet_NaN

numeric_limits::has_signaling_NaN

numeric_limits::has_denorm

numeric_limits::has_denorm_loss

numeric_limits::round_style

numeric_limits::is_iec559

numeric_limits::is_bounded

numeric_limits::is_modulo

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numeric_limits::max_digits10 (C++11)

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numeric_limits::min_exponent

numeric_limits::min_exponent10

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numeric_limits::max_exponent10

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numeric_limits::tinyness_before

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numeric_limits::min

numeric_limits::lowest (C++11)

numeric_limits::max

numeric_limits::epsilon

numeric_limits::round_error

numeric_limits::infinity

numeric_limits::quiet_NaN

numeric_limits::signaling_NaN

numeric_limits::denorm_min

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float_round_style

float_denorm_style

 

static const bool is_exact;		(until C++11)
static constexpr bool is_exact;		(since C++11)

The value of std::numeric_limits<T>::is_exact is true for all arithmetic types T that use exact representation.

Standard specializations

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

Notes

While all fundamental types T for which std::numeric_limits<T>::is_exact==true are integer types, a library may define exact types that aren't integers, e.g. a rational arithmetics type representing fractions.

See also

is_integer [static]	identifies integer types (public static member constant)
is_signed [static]	identifies signed types (public static member constant)
is_bounded [static]	identifies types that represent a finite set of values (public static member constant)