| Defined in header <<fenv.h>> | ||
|---|---|---|
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.
Parameters
| excepts | - | bitmask listing the exception flags to test |
Return value
Bitwise OR of the floating-point exception macros that are both included in excepts and correspond to floating-point exceptions currently set.
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_MAX*2.0 = %f\n", DBL_MAX*2.0); /* 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
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)
See also
| (C99) | clears the specified floating-point status flags (function) |
C++ documentation for fetestexcept | |
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