std::numeric_limits<T>::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
char8_t (C++20) false
char16_t (C++11) false
char32_t (C++11) false
short false
unsigned short false
int false
unsigned int false
long false
unsigned long false
long long (C++11) false
unsigned long long (C++11) false
float usually true
double usually true
long double usually true

See also

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