FE_DOWNWARD, FE_TONEAREST, FE_TOWARDZERO, FE_UPWARD
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| Elemento definito nell'header <cfenv>
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| #define FE_DOWNWARD /*implementation defined*/ |
(dal C++11) | |
| #define FE_TONEAREST /*implementation defined*/ |
(dal C++11) | |
| #define FE_TOWARDZERO /*implementation defined*/ |
(dal C++11) | |
| #define FE_UPWARD /*implementation defined*/ |
(dal C++11) | |
Ciascuna di queste costanti macro restituisce un negativo espressione intero costante, che può utilizzare con me std::fesetround e std::fegetround per indicare uno dei supportate virgola mobile modalità di arrotondamento. L'applicazione può definire ulteriori costanti modalità di arrotondamento nel
<cfenv>, che dovrebbero iniziare con FE_ seguita da almeno una lettera maiuscola. Ogni macro è definito solo se supportato.Original:
Each of these macro constants expands to a nonnegative integer constant expression, which can me used with std::fesetround and std::fegetround to indicate one of the supported floating-point rounding modes. The implementation may define additional rounding mode constants in
<cfenv>, which should all begin with FE_ followed by at least one uppercase letter. Each macro is only defined if it is supported.The text has been machine-translated via Google Translate.
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Sulla maggior parte delle implementazioni, queste costanti macro espandere i valori uguali ai valori di FLT_ROUNDS e std::float_round_style
Original:
On most implementations, these macro constants expand to the values equal to the values of FLT_ROUNDS and std::float_round_style
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| Constant
Original: Constant The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Explanation |
FE_DOWNWARD
|
arrotondamento verso l'infinito negativo
Original: rounding towards negative infinity The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
FE_TONEAREST
|
arrotondamento verso l'intero più vicino
Original: rounding towards nearest integer The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
FE_TOWARDZERO
|
arrotondamento verso lo zero
Original: rounding towards zero The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
FE_UPWARD
|
arrotondamento verso l'infinito positivo
Original: rounding towards positive infinity The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Ulteriori modalità di arrotondamento può essere supportato da una implementazione.
Original:
Additional rounding modes may be supported by an implementation.
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[modifica] 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
[modifica] Vedi anche
| indica virgola mobile modalità di arrotondamento Original: indicates floating-point rounding modes The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (enum) | |
| (C++11) (C++11) |
ottiene o imposta la direzione di arrotondamento Original: gets or sets rounding direction The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione) |
