FE_DFL_ENV
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<tbody> </tbody>| Definido no cabeçalho <cfenv>
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#define FE_DFL_ENV /*implementation defined*/ |
(desde 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.
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.
You can help to correct and verify the translation. Click here for instructions.
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();
}
Saída:
On startup:
rounding to nearest
Before restoration:
underflow is raised
overflow is raised
rounding up
After reset to default:
rounding to nearest
Veja também
(C++11) |
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) |
(C++11) |
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) |