FE_DFL_ENV
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| Déclaré dans l'en-tête <cfenv>
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| #define FE_DFL_ENV /*implementation defined*/ |
(depuis C++11) | |
Le FE_DFL_ENV macro constante développe en une expression de const std::fenv_t* type, qui pointe vers une copie complète de la valeur par défaut en virgule flottante environnement, qui est, de l'environnement tel qu'il est chargé au démarrage du programme .
Original:
The macro constant FE_DFL_ENV expands to an expression of type const std::fenv_t*, which points to a full copy of the default floating-point environment, that is, the environment as loaded at program startup.
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Macros complémentaires qui commencent par
FE_ suivie par des lettres majuscules, et le const std::fenv_t* nature, peuvent être pris en charge par une mise en œuvre .Original:
Additional macros that begin with
FE_ followed by uppercase letters, and have the type const std::fenv_t*, may be supported by an implementation.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
[modifier] Exemple
#include <iostream> #include <cfenv> #pragma STDC FENV_ACCESS ON void show_env() { int e = std::fetestexcept(FE_ALL_EXCEPT); if(e & FE_DIVBYZERO) std::cout << "division by zero is raised\n"; if(e & FE_INEXACT) std::cout << "inexact is raised\n"; if(e & FE_INVALID) std::cout << "invalid is raised\n"; if(e & FE_UNDERFLOW) std::cout << "underflow is raised\n"; if(e & FE_OVERFLOW) std::cout << "overflow is raised\n"; int r = std::fegetround(); switch(r) { case FE_DOWNWARD: std::cout << "rounding down\n"; break; case FE_TONEAREST: std::cout << "rounding to nearest\n"; break; case FE_TOWARDZERO: std::cout << "rounding to zero\n"; break; case FE_UPWARD: std::cout << "rounding up\n"; break; } } int main() { std::cout << "On startup: \n"; show_env(); std::feraiseexcept(FE_UNDERFLOW | FE_OVERFLOW); std::fesetround(FE_UPWARD); std::cout << "\nBefore restoration: \n"; show_env(); std::fesetenv(FE_DFL_ENV); std::cout << "\nAfter reset to default: \n"; show_env(); }
Résultat :
On startup: rounding to nearest Before restoration: underflow is raised overflow is raised rounding up After reset to default: rounding to nearest
[modifier] Voir aussi
| (C++11) |
sauvegarde ou restaure l'environnement actuel point flottant Original: saves or restores the current floating point environment The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) |
| (C++11) |
restaure l'environnement en virgule flottante et soulève le lever des exceptions précédemment Original: restores the floating-point environment and raises the previously raise exceptions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction) |
