fetestexcept

Parameters

excepts

Bitmask value: A combination (with bitwise OR) of any number of floating-point exception values supported by the implementation:

macro value	description
FE_DIVBYZERO	Pole error: division by zero, or some other asymptotically infinite result (from finite arguments).
FE_INEXACT	Inexact: the result is not exact.
FE_INVALID	Domain error: At least one of the arguments is a value for which the function is not defined.
FE_OVERFLOW	Overflow range error: The result is too large in magnitude to be represented as a value of the return type.
FE_UNDERFLOW	Underflow range error: The result is too small in magnitude to be represented as a value of the return type.
FE_ALL_EXCEPT	All exceptions (selects all of the exceptions supported by the implementation).

Certain library implementations may support additional floating-point exception values (with their corresponding macros also beginning with FE_).

Libraries may define in <fenv.h> only the macro values above they support (the others may not be defined).

At least all of the above macro values are defined in <cfenv> (even if not supported by the implementation).

Return Value

Example

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/* fetestexcept example */
#include <stdio.h>      /* puts */
#include <fenv.h>       /* feraiseexcept, fetestexcept, FE_* */
#pragma STDC FENV_ACCESS on
double fn (double x) {
  /* some function for which zero is a domain and range error */
  if (x==0.0) feraiseexcept(FE_INVALID|FE_OVERFLOW);
  return x;
}
int main ()
{
  int fe;
  feclearexcept (FE_ALL_EXCEPT);
  fn (0.0);
  /* testing for single exception: */
  if (fetestexcept(FE_OVERFLOW)) puts ("FE_OVERFLOW is set");
  /* testing multiple exceptions: */
  fe = fetestexcept (FE_ALL_EXCEPT);
  puts ("The following exceptions are set:");
  if (fe & FE_DIVBYZERO) puts ("FE_DIVBYZERO");
  if (fe & FE_INEXACT)   puts ("FE_INEXACT");
  if (fe & FE_INVALID)   puts ("FE_INVALID");
  if (fe & FE_OVERFLOW)  puts ("FE_OVERFLOW");
  if (fe & FE_UNDERFLOW) puts ("FE_UNDERFLOW");
  return 0;
}

FE_OVERFLOW is set
The following exceptions are set:
FE_INVALID
FE_OVERFLOW

Data races

Exceptions

See also

feraiseexcept

Raise floating-point exception (function)

feclearexcept

Clear floating-point exceptions (function)

feholdexcept

Hold floating-point exceptions (function)