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FE_DIVBYZERO, FE_INEXACT, FE_INVALID, FE_OVERFLOW, FE_UNDERFLOW, FE_ALL_EXCEPT

Da cppreference.com.
< cpp‎ | numeric‎ | fenv

 
 
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
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iota(C++11)
accumulate
inner_product
adjacent_difference
partial_sum
 
Virgola mobile ambiente
Funzioni
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 costanti
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>
#define FE_DIVBYZERO    /*implementation defined power of 2*/
(dal C++11)
#define FE_INEXACT      /*implementation defined power of 2*/
(dal C++11)
#define FE_INVALID      /*implementation defined power of 2*/
(dal C++11)
#define FE_OVERFLOW     /*implementation defined power of 2*/
(dal C++11)
#define FE_UNDERFLOW    /*implementation defined power of 2*/
(dal C++11)
#define FE_ALL_EXCEPT  FE_DIVBYZERO | FE_INEXACT | \

                       FE_INVALID | FE_OVERFLOW |  \

                       FE_UNDERFLOW
(dal C++11)
Tutte queste costanti macro (ad eccezione FE_ALL_EXCEPT) espandersi in interi espressioni costanti che sono potenze di 2 distinti, che identificano in modo univoco tutti supportati eccezioni a virgola mobile. Ogni macro è definito solo se supportato.
Original:
All these macro constants (except FE_ALL_EXCEPT) expand to integer constant expressions that are distinct powers of 2, which uniquely identify all supported floating-point exceptions. Each macro is only defined if it is supported.
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Il FE_ALL_EXCEPT macro costante, che espande alla OR fra tutti FE_* altri, è sempre definito e se è zero virgola mobile eccezioni non sono supportati dall'implementazione.
Original:
The macro constant FE_ALL_EXCEPT, which expands to the bitwise OR of all other FE_*, is always defined and is zero if floating-point exceptions are not supported by the implementation.
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Constant
Original:
Constant
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Explanation
FE_DIVBYZERO
divisione per zero durante l'operazione precedente virgola mobile
Original:
division by zero occurred during the earlier floating-point operation
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FE_INEXACT
inesatta risultato: arrotondamento è necessario memorizzare il risultato dell'operazione precedente virgola mobile
Original:
inexact result: rounding was necessary to store the result of the earlier floating-point operation
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FE_INVALID
operazione non valida: l'operazione precedente a virgola mobile non potevano eseguire
Original:
invalid operation: the earlier floating-point operation could not performed
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FE_OVERFLOW
il risultato del precedente virgola mobile è troppo grande per essere rappresentabile
Original:
the result of the earlier floating-point operation was too large to be representable
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FE_UNDERFLOW
il risultato dell'operazione precedente virgola mobile era subnormale
Original:
the result of the earlier floating-point operation was subnormal
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FE_ALL_EXCEPT
OR bit per bit di tutte le versioni eccezioni a virgola mobile
Original:
bitwise OR of all supported floating-point exceptions
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L'implementazione può definire costanti macro supplementari <cfenv> per individuare ulteriori eccezioni a virgola mobile. Tutte le costanti iniziano con tali FE_ seguita da almeno una lettera maiuscola.
Original:
The implementation may define additional macro constants in <cfenv> to identify additional floating-point exceptions. All such constants begin with FE_ followed by at least one uppercase letter.
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[modifica] Esempio

[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

[modifica] Vedi anche

definisce il meccanismo di gestione degli errori utilizzato dai comuni funzioni matematiche
Original:
defines the error handling mechanism used by the common mathematical functions
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(macro costante) [edit]