FE_DIVBYZERO, FE_INEXACT, FE_INVALID, FE_OVERFLOW, FE_UNDERFLOW, FE_ALL_EXCEPT
From cppreference.com
| Defined in header <fenv.h>
|
||
| #define FE_DIVBYZERO /*implementation defined power of 2*/ |
(since C99) | |
| #define FE_INEXACT /*implementation defined power of 2*/ |
(since C99) | |
| #define FE_INVALID /*implementation defined power of 2*/ |
(since C99) | |
| #define FE_OVERFLOW /*implementation defined power of 2*/ |
(since C99) | |
| #define FE_UNDERFLOW /*implementation defined power of 2*/ |
(since C99) | |
| #define FE_ALL_EXCEPT FE_DIVBYZERO | FE_INEXACT | \ FE_INVALID | FE_OVERFLOW | \ |
(since C99) | |
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.
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.
| Constant | Explanation |
FE_DIVBYZERO
|
pole error occurred in an earlier floating-point operation |
FE_INEXACT
|
inexact result: rounding was necessary to store the result of an earlier floating-point operation |
FE_INVALID
|
domain error occurred in an earlier floating-point operation |
FE_OVERFLOW
|
the result of an earlier floating-point operation was too large to be representable |
FE_UNDERFLOW
|
the result of an earlier floating-point operation was subnormal with a loss of precision |
FE_ALL_EXCEPT
|
bitwise OR of all supported floating-point exceptions |
The implementation may define additional macro constants in <fenv.h> to identify additional floating-point exceptions. All such constants begin with FE_ followed by at least one uppercase letter.
See math_errhandling for further details.
[edit] Example
Run this code
#include <stdio.h> #include <math.h> #include <float.h> #include <fenv.h> #pragma STDC FENV_ACCESS ON void show_fe_exceptions(void) { printf("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"); feclearexcept(FE_ALL_EXCEPT); printf("\n"); } int main(void) { printf("MATH_ERREXCEPT is %s\n", math_errhandling & MATH_ERREXCEPT ? "set" : "not set"); printf("0.0/0.0 = %f\n", 0.0/0.0); show_fe_exceptions(); printf("1.0/0.0 = %f\n", 1.0/0.0); show_fe_exceptions(); printf("1.0/10.0 = %f\n", 1.0/10.0); show_fe_exceptions(); printf("sqrt(-1) = %f\n", sqrt(-1)); show_fe_exceptions(); printf("DBL_MAX*2.0 = %f\n", DBL_MAX*2.0); show_fe_exceptions(); printf("nextafter(DBL_MIN/pow(2.0,52),0.0) = %.1f\n", nextafter(DBL_MIN/pow(2.0,52),0.0)); show_fe_exceptions(); }
Possible output:
MATH_ERREXCEPT is set 0.0/0.0 = nan exceptions raised: FE_INVALID 1.0/0.0 = inf exceptions raised: FE_DIVBYZERO 1.0/10.0 = 0.100000 exceptions raised: FE_INEXACT sqrt(-1) = -nan exceptions raised: FE_INVALID DBL_MAX*2.0 = inf exceptions raised: FE_INEXACT FE_OVERFLOW nextafter(DBL_MIN/pow(2.0,52),0.0) = 0.0 exceptions raised: FE_INEXACT FE_UNDERFLOW
[edit] References
- C11 standard (ISO/IEC 9899:2011):
- 7.6/6 Floating-point environment <fenv.h> (p: 207)
- C99 standard (ISO/IEC 9899:1999):
- 7.6/5 Floating-point environment <fenv.h> (p: 188)
[edit] See also
| (C99)(C99)(C99) |
defines the error handling mechanism used by the common mathematical functions (macro constant) |
| C++ documentation for floating-point exception macros
| |
