std::numeric_limits::has_quiet_NaN

 

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

The value of std::numeric_limits<T>::has_quiet_NaN is true for all types T capable of representing the special value "Quiet Not-A-Number". This constant is meaningful for all floating-point types and is guaranteed to be true if std::numeric_limits<T>::is_iec559 == true.

Standard specializations

T	value of std::numeric_limits<T>::has_quiet_NaN
/* non-specialized */	false
bool	false
char	false
signed char	false
unsigned char	false
wchar_t	false
char16_t	false
char32_t	false
short	false
unsigned short	false
int	false
unsigned int	false
long	false
unsigned long	false
long long	false
unsigned long long	false
float	usually true
double	usually true
long double	usually true

See also

quiet_NaN [static]	returns a quiet NaN value of the given floating-point type (public static member function)
has_infinity [static]	identifies floating-point types that can represent the special value "positive infinity" (public static member constant)
has_signaling_NaN [static]	identifies floating-point types that can represent the special value "signaling not-a-number" (NaN) (public static member constant)