std::numeric_limits::signaling_NaN

 

C++

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Gli operatori relazionali Original: Relational operators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

rel_ops::operator!= rel_ops::operator> rel_ops::operator<= rel_ops::operator>=

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tuple (C++11)

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piecewise_construct (C++11)

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declval (C++11)

 

Tipo di supporto

Tipi base Original: Basic types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
Tipi fondamentali
Larghezza fissa interi tipi(C++11)
ptrdiff_t size_t max_align_t (C++11)	nullptr_t (C++11) offsetof NULL
Limiti numerici Original: Numeric limits The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
numeric_limits
C numerico limita interfaccia
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type_info type_index (C++11)	bad_typeid bad_cast
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is_void (C++11) is_array (C++11) is_pointer (C++11) is_enum (C++11) is_union (C++11) is_class (C++11) is_function (C++11)	is_object (C++11) is_scalar (C++11) is_compound (C++11) is_integral (C++11) is_floating_point (C++11) is_fundamental (C++11) is_arithmetic (C++11)
is_reference (C++11)
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std::numeric_limits

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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

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numeric_limits::digits10

numeric_limits::max_digits10 (C++11)

numeric_limits::radix

numeric_limits::min_exponent

numeric_limits::min_exponent10

numeric_limits::max_exponent

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 T signaling_NaN()		(fino al c++11)
staticconstexpr T signaling_NaN()		(dal C++11)

Restituisce la speciale "segnalazione not-a-numero" valore, come rappresentato dalla virgola mobile T tipo. Ha senso solo se std::numeric_limits<T>::has_signaling_NaN==true. In IEEE 754, la rappresentazione binaria più comune di numeri in virgola mobile, qualsiasi valore con tutti i bit del set esponente e almeno un bit del set frazione rappresenta un NaN. Esso è definito dall'implementazione quali valori della frazione rappresentano NaN tranquillo o segnalazione, e se il bit di segno è significativo.

Original:

Returns the special value "signaling not-a-numero", as represented by the floating-point type T. Only meaningful if std::numeric_limits<T>::has_signaling_NaN==true. In IEEE 754, the most common binary representation of floating-point numbers, any value with all bits of the exponent set and at least one bit of the fraction set represents a NaN. It is implementation-defined which values of the fraction represent quiet or signaling NaNs, and whether the sign bit is meaningful.

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Valore di ritorno

T	std::numeric_limits<T>::quiet_NaN()
/* non-specialized */	T();
bool	false
char	​0​
signedchar	​0​
unsignedchar	​0​
wchar_t	​0​
char16_t	​0​
char32_t	​0​
short	​0​
unsignedshort	​0​
int	​0​
unsignedint	​0​
long	​0​
unsignedlong	​0​
longlong	​0​
unsignedlonglong	​0​
float	implementazione definita Original: implementation-defined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
double	implementazione definita Original: implementation-defined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
longdouble	implementazione definita Original: implementation-defined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Eccezioni

noexcept specification:  

noexcept

  (dal C++11)

Note

Un NaN mai uguale a se stesso confronto. Copia di un NaN non può conservare la sua rappresentazione po.

Original:

A NaN never compares equal to itself. Copying a NaN may not preserve its bit representation.

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Quando un NaN di segnalazione viene utilizzato come argomento per un'espressione aritmetica, l'appropriato virgola mobile eccezione può essere sollevata e il NaN è "calmato", cioè, l'espressione restituisce un tranquillo NaN.

Original:

When a signaling NaN is used as an argument to an arithmetic expression, the appropriate floating-point exception may be raised and the NaN is "quieted", that is, the expression returns a quiet NaN.

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Esempio

Dimostra l'uso di una segnalazione NaN sollevare una virgola mobile eccezione

Original:

Demonstrates the use of a signaling NaN to raise a floating-point exception

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#include <iostream>#include <limits>#include <cfenv>#pragma STDC_FENV_ACCESS onvoid show_fe_exceptions(){int n =std::fetestexcept(FE_ALL_EXCEPT);if(n &FE_INVALID)std::cout<<"FE_INVALID is raised\n";elseif(n ==0)std::cout<<"no exceptions are raised\n";std::feclearexcept(FE_ALL_EXCEPT);}int main(){double snan =std::numeric_limits<double>::signaling_NaN();std::cout<<"After sNaN was obtained "; show_fe_exceptions();double qnan = snan *2.0;std::cout<<"After sNaN was multiplied by 2 "; show_fe_exceptions();double qnan2 = qnan *2.0;std::cout<<"After the quieted NaN was multiplied by 2 "; show_fe_exceptions();std::cout<<"The result is "<< qnan2 <<'\n';}

Output:

After sNaN was obtained no exceptions are raised After sNaN was multiplied by 2 FE_INVALID is raised After the quieted NaN was multiplied by 2 no exceptions are raised The result is nan

Vedi anche

has_signaling_NaN [statico]	identifica i tipi a virgola mobile che possono rappresentare il valore speciale "segnalazione non-a-number" (NaN) Original: identifies floating-point types that can represent the special value "signaling not-a-number" (NaN) The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (pubblico membro statico costante)
quiet_NaN [statico]	restituisce un valore NaN tranquilla di un dato tipo a virgola mobile Original: returns a quiet NaN value of the given floating-point type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico statico)