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std::fetestexcept

De cppreference.com
< cpp‎ | numeric‎ | fenv

 
 
Bibliothèque Numerics
Fonctions mathématiques courantes
Virgule flottante environnement
Nombres complexes
Tableaux numériques
La génération de nombres pseudo-aléatoires
Moment de la compilation arithmétique rationnelle (C++11)
Génériques des opérations numériques
Original:
Generic numeric operations
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iota (C++11)
accumulate
inner_product
adjacent_difference
partial_sum
 
Virgule flottante environnement
Fonctions
Original:
Functions
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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 constantes
Original:
Macro constants
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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)
 
Defined in header <cfenv>
int fetestexcept( int excepts );
(depuis C++11)
Détermine le sous-ensemble spécifié de la des exceptions à virgule flottante sont indiqués. Le excepts argument est un OU bit à bit de la flottant point exception des macros .
Original:
Determines which of the specified subset of the floating point exceptions are currently set. The argument excepts is a bitwise OR of the flottant point exception des macros.
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Sommaire

[modifier] Paramètres

excepts -
masque la liste des drapeaux d'exceptions à tester
Original:
bitmask listing the exception flags to test
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[modifier] Retourne la valeur

OU binaire entre les macros exception de virgule flottante qui sont tous deux inclus dans excepts et correspondent aux exceptions de virgule flottante actuellement définies .
Original:
Bitwise OR of the floating-point exception macros that are both included in excepts and correspond to floating-point exceptions currently set.
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[modifier] Exemple

[edit]
#include <iostream>
#include <cfenv>
#include <cmath>
 
#pragma STDC FENV_ACCESS ON
 
volatile double zero = 0.0; // volatile not needed where FENV_ACCESS is supported
volatile double one = 1.0;  // volatile not needed where FENV_ACCESS is supported
 
int main()
{
    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout <<  "1.0/0.0 = " << 1.0 / zero << '\n';
    if(std::fetestexcept(FE_DIVBYZERO)) {
        std::cout << "division by zero reported\n";
    } else {
        std::cout << "divsion by zero not reported\n";
    }
 
    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "1.0/10 = " << one/10 << '\n';
    if(std::fetestexcept(FE_INEXACT)) {
        std::cout << "inexact result reported\n";
    } else {
        std::cout << "inexact result not reported\n";
    }
 
    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "sqrt(-1) = " << std::sqrt(-1) << '\n';
    if(std::fetestexcept(FE_INVALID)) {
        std::cout << "invalid result reported\n";
    } else {
        std::cout << "invalid result not reported\n";
    }
}

Résultat :

1.0/0.0 = inf
division by zero reported
1.0/10 = 0.1
inexact result reported
sqrt(-1) = -nan
invalid result reported

[modifier] Voir aussi

efface les indicateurs d'état spécifiées à virgule flottante
Original:
clears the specified floating-point status flags
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(fonction) [edit]