fetestexcept - cppreference.com (original) (raw)
| | | | | -------------------------------- | | ----------- | | int fetestexcept( int excepts ); | | (since C99) |
Determines which of the specified subset of the floating-point exceptions are currently set. The argument excepts is a bitwise OR of the floating-point exception macros.
[edit] Parameters
| excepts | - | bitmask listing the exception flags to test |
|---|
[edit] Return value
Bitwise OR of the floating-point exception macros that are both included in excepts and correspond to floating-point exceptions currently set.
[edit] Example
#include <stdio.h> #include <math.h> #include <fenv.h> #include <float.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"); } int main(void) { /* Show default set of exception flags. / show_fe_exceptions(); / Perform some computations which raise exceptions. / printf("1.0/0.0 = %f\n", 1.0/0.0); / FE_DIVBYZERO / printf("1.0/10.0 = %f\n", 1.0/10.0); / FE_INEXACT / printf("sqrt(-1) = %f\n", sqrt(-1)); / FE_INVALID / printf("DBL_MAX2.0 = %f\n", DBL_MAX2.0); / FE_INEXACT FE_OVERFLOW / printf("nextafter(DBL_MIN/pow(2.0,52),0.0) = %.1f\n", nextafter(DBL_MIN/pow(2.0,52),0.0)); / FE_INEXACT FE_UNDERFLOW */ show_fe_exceptions(); return 0; }
Output:
current exceptions raised: none 1.0/0.0 = inf 1.0/10.0 = 0.100000 sqrt(-1) = -nan DBL_MAX*2.0 = inf nextafter(DBL_MIN/pow(2.0,52),0.0) = 0.0 current exceptions raised: FE_DIVBYZERO FE_INEXACT FE_INVALID FE_OVERFLOW FE_UNDERFLOW
[edit] References
C11 standard (ISO/IEC 9899:2011):
7.6.2.5 The fetestexcept function (p: 211-212)
C99 standard (ISO/IEC 9899:1999):
7.6.2.5 The fetestexcept function (p: 192-193)