| Functions | ||||
(C99) | ||||
(C99) | ||||
(C99) | ||||
(C99)(C99) | ||||
(C99)(C99) | ||||
(C99) | ||||
(C99) | ||||
(C99) | ||||
| Macro constants | ||||
FE_DFL_ENV (C99) |
Defined in header <fenv.h> | ||
#define FE_DFL_ENV /*implementation defined*/ | (since C99) | |
The macro constantFE_DFL_ENV expands to an expression of typeconst 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 withFE_ followed by uppercase letters, and have the typeconst fenv_t*, may be supported by an implementation.
#include <stdio.h>#include <fenv.h> #pragma STDC FENV_ACCESS ON void show_fe_exceptions(void){printf("current exceptions raised: ");if(fetestexcept(FE_DIVBYZERO))printf(" FE_DIVBYZERO");if(fetestexcept(FE_INEXACT))printf(" FE_INEXACT");if(fetestexcept(FE_INVALID))printf(" FE_INVALID");if(fetestexcept(FE_OVERFLOW))printf(" FE_OVERFLOW");if(fetestexcept(FE_UNDERFLOW))printf(" FE_UNDERFLOW");if(fetestexcept(FE_ALL_EXCEPT)==0)printf(" none");printf("\n");} void show_fe_rounding_method(void){printf("current rounding method: ");switch(fegetround()){caseFE_TONEAREST:printf("FE_TONEAREST");break;caseFE_DOWNWARD:printf("FE_DOWNWARD");break;caseFE_UPWARD:printf("FE_UPWARD");break;caseFE_TOWARDZERO:printf("FE_TOWARDZERO");break;default:printf("unknown");};printf("\n");} void show_fe_environment(void){ show_fe_exceptions(); show_fe_rounding_method();} int main(){printf("On startup:\n"); show_fe_environment(); // Change environmentfesetround(FE_DOWNWARD);// change rounding modeferaiseexcept(FE_INVALID);// raise exceptionprintf("\nBefore restoration:\n"); show_fe_environment(); fesetenv(FE_DFL_ENV);// restoreprintf("\nAfter restoring default environment:\n"); show_fe_environment();}
Output:
On startup:current exceptions raised: nonecurrent rounding method: FE_TONEAREST Before restoration:current exceptions raised: FE_INVALIDcurrent rounding method: FE_DOWNWARD After restoring default environment:current exceptions raised: nonecurrent rounding method: FE_TONEAREST
(C99) | saves or restores the current floating-point environment (function)[edit] |
(C99) | restores the floating-point environment and raises the previously raise exceptions (function)[edit] |
C++ documentation forFE_DFL_ENV | |
