std::fegetround, std::fesetround

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

Contenitori

Algoritmi

Iteratori

Libreria matematca

Input/output

Localizzazione

Espressioni regolari(C++11)

Operazioni atomicche(C++11)

Multithreading(C++11)

 

Numeri libreria

Comuni funzioni matematiche

Virgola mobile ambiente

I numeri complessi

Array numerici

Pseudo-casuale generazione

In fase di compilazione aritmetica razionale(C++11)

Generici operazioni numeriche Original: Generic numeric operations The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

iota (C++11)

accumulate

inner_product

adjacent_difference

partial_sum

 

Virgola mobile ambiente

Funzioni Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

feclearexcept (C++11)

fetestexcept (C++11)

feraiseexcept (C++11)

fegetexceptflag fesetexceptflag (C++11) (C++11)

fegetround fesetround (C++11) (C++11)

fegetenv fesetenv (C++11)

feholdexcept (C++11)

feupdateenv (C++11)

Macro costanti Original: Macro constants The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

FE_ALL_EXCEPT FE_DIVBYZERO FE_INEXACT FE_INVALID FE_OVERFLOW FE_UNDERFLOW (C++11)

FE_DOWNWARD FE_TONEAREST FE_TOWARDZERO FE_UPWARD (C++11)

FE_DFL_ENV (C++11)

 

Elemento definito nell'header <cfenv>
int fesetround(int round )	(1)	(dal C++11)
int fegetround()	(2)	(dal C++11)

1)

I tentativi di stabilire in virgola mobile direzione arrotondamento pari al round argomento, che dovrebbe essere uno dei galleggiante macro arrotondamento punto.

Original:

Attempts to establish the floating-point rounding direction equal to the argument round, which is expected to be one of the galleggiante macro arrotondamento punto.

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2)

Restituisce il valore della galleggiante arrotondamento macro punto che corrisponde alla direzione di arrotondamento corrente.

Original:

Returns the value of the galleggiante arrotondamento macro punto that corresponds to the current rounding direction.

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Parametri

round

-

arrotondamento direzione, uno dei galleggiante macro arrotondamento punto Original: rounding direction, one of galleggiante macro arrotondamento punto The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Valore di ritorno

1)

​0​ in caso di successo, non-zero altrimenti.

Original:

​0​ on success, non-zero otherwise.

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2)

la galleggiante arrotondamento macro punto descrive la direzione corrente arrotondamento o un valore negativo se la direzione non può essere determinata

Original:

the galleggiante arrotondamento macro punto describing the current rounding direction or a negative value if the direction cannot be determined

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Esempio

#include <cmath>#include <cfenv>#include <iostream>   int main(){#pragma STDC FENV_ACCESS ON std::fesetround(FE_DOWNWARD);std::cout<<"rounding using FE_DOWNWARD: \n"<<std::fixed<<" 12.0 -> "<<std::nearbyint(12.0)<<'\n'<<" 12.1 -> "<<std::nearbyint(12.1)<<'\n'<<"-12.1 -> "<<std::nearbyint(-12.1)<<'\n'<<" 12.5 -> "<<std::nearbyint(12.5)<<'\n'<<" 12.9 -> "<<std::nearbyint(12.9)<<'\n'<<"-12.9 -> "<<std::nearbyint(-12.9)<<'\n'<<" 13.0 -> "<<std::nearbyint(13.0)<<'\n'; std::fesetround(FE_TONEAREST);std::cout<<"rounding using FE_TONEAREST: \n"<<" 12.0 -> "<<std::nearbyint(12.0)<<'\n'<<" 12.1 -> "<<std::nearbyint(12.1)<<'\n'<<"-12.1 -> "<<std::nearbyint(-12.1)<<'\n'<<" 12.5 -> "<<std::nearbyint(12.5)<<'\n'<<" 12.9 -> "<<std::nearbyint(12.9)<<'\n'<<"-12.9 -> "<<std::nearbyint(-12.9)<<'\n'<<" 13.0 -> "<<std::nearbyint(13.0)<<'\n';}

Output:

rounding using FE_DOWNWARD: 12.0 -> 12.000000 12.1 -> 12.000000 -12.1 -> -13.000000 12.5 -> 12.000000 12.9 -> 12.000000 -12.9 -> -13.000000 13.0 -> 13.000000 rounding using FE_TONEAREST: 12.0 -> 12.000000 12.1 -> 12.000000 -12.1 -> -12.000000 12.5 -> 12.000000 12.9 -> 13.000000 -12.9 -> -13.000000 13.0 -> 13.000000

Vedi anche

nearbyint (C++11)	numero intero più vicino utilizzando la modalità corrente di arrotondamento Original: nearest integer using current rounding mode The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione)
rint lrint llrint (C++11) (C++11) (C++11)	numero intero più vicino utilizzando la modalità corrente di arrotondamento ad eccezione se il risultato è diverso Original: nearest integer using current rounding mode with exception if the result differs The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione)