FE_DFL_ENV
From cppreference.com
| Defined in header <cfenv>
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||
#define FE_DFL_ENV /*implementation defined*/
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(since C++11) | |
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.
Additional macros that begin with FE_ followed by uppercase letters, and have the type const std::fenv_t*, may be supported by an implementation.
Example
Run this code
#include <cfenv>
#include <iostream>
// #pragma STDC FENV_ACCESS ON
void show_env()
{
const 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";
switch (std::fegetround())
{
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
See also
(C++11) |
saves or restores the current floating-point environment (function) |
(C++11) |
restores the floating-point environment and raises the previously raised exceptions (function) |
C documentation for FE_DFL_ENV
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