Espaços nominais
Variantes
Acções

FE_DFL_ENV

Da cppreference.com
< cpp‎ | numeric‎ | fenv

 
 
Biblioteca numéricos
Funções matemáticas comuns
De ponto flutuante ambiente
Números complexos
Matrizes numéricas
Pseudo-aleatório de geração de números
Tempo de compilação aritmética racional (C++11)
Genéricos operações numéricas
Original:
Generic numeric operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
iota(C++11)
accumulate
inner_product
adjacent_difference
partial_sum
 
De ponto flutuante ambiente
Funções
Original:
Functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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)
Constantes de macros
Original:
Macro constants
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
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_DFL_ENV  /*implementation defined*/
(a partir do C++ 11)
O FE_DFL_ENV macro constante expande a uma expressão de const std::fenv_t* tipo, que aponta para uma cópia completa do ambiente padrão de ponto flutuante, ou seja, o meio ambiente como carregado na inicialização do programa.
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.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Macros adicionais que começam com FE_ seguido por letras maiúsculas e têm o const std::fenv_t* tipo, pode ser suportado por uma implementação.
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.

[editar] Exemplo

#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();
}

Output:

On startup: 
rounding to nearest
 
Before restoration: 
underflow is raised
overflow is raised
rounding up
 
After reset to default: 
rounding to nearest

[editar] Veja também

salva ou restaura o ambiente actual ponto flutuante
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.

(função) [edit]
restaura o ambiente de ponto flutuante e levanta a anteriormente levantar exceções
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.

(função) [edit]