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std::fetestexcept

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< cpp‎ | numeric‎ | fenv

 
 
Numerik-Bibliothek
Gemeinsame mathematischen Funktionen
Floating-Point-Umgebung
Komplexe Zahlen
Numerische Arrays
Pseudo-Zufallszahlen
Compile-time rationale Arithmetik (C++11)
Generische numerische Operationen
Original:
Generic numeric operations
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iota(C++11)
accumulate
inner_product
adjacent_difference
partial_sum
 
Floating-Point-Umgebung
Funktionen
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)
Makro Konstanten
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 );
(seit C++11)
Legt fest, welche der angegebenen Teilmenge der Gleitkomma-Ausnahmen sind derzeit eingestellt. Das Argument excepts ist eine bitweise OR der Gleitkomma-Ausnahme Makros .
Original:
Determines which of the specified subset of the floating point exceptions are currently set. The argument excepts is a bitwise OR of the Gleitkomma-Ausnahme Makros.
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Inhaltsverzeichnis

[Bearbeiten] Parameter

excepts -
Bitmaske auflistet Ausnahme Flags zu testen
Original:
bitmask listing the exception flags to test
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[Bearbeiten] Rückgabewert

Bitweise ODER-Verknüpfung der Gleitkomma-Ausnahme-Makros, die sowohl in excepts enthalten und entsprechen den Gleitkomma-Exceptions aktuell eingestellte .
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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[Bearbeiten] Beispiel

[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";
    }
}

Output:

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

[Bearbeiten] Siehe auch

löscht die angegebene Fließkomma-Status-Flags
Original:
clears the specified floating-point status flags
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(Funktion) [edit]