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× C Standard Library


The FE_ALL_EXCEPT macro expands to the bitwise OR of all possible floating-point exceptions defined in <fenv.h>. If no floating-point exceptions are supported by the implementation, this macro is defined as 0 (zero).

It can be used with functions that expect a bitmask of possible floating point exceptions as one of its arguments: feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag, or fetestexcept.

Definition in the <fenv.h> header file is:

#define FE_ALL_EXCEPT  FE_DIVBYZERO | FE_INEXACT | FE_INVALID 
                       | FE_OVERFLOW | FE_UNDERFLOW                

MacrosDescription
FE_DIVBYZERO Pole error exception occurred in an earlier floating-point operation.
FE_INEXACT Inexact result exception occurred in an earlier floating-point operation (rounding was necessary to store the result).
FE_INVALID Invalid argument exception occurred (domain error occurred) in an earlier floating-point operation.
FE_OVERFLOW Overflow range error exception occurred in an earlier floating-point operation (result was too large to be representable).
FE_UNDERFLOW Underflow range error exception occurred in an earlier floating-point operation (result was subnormal with a loss of precision).
FE_ALL_EXCEPT Bitwise OR of all supported floating-point exceptions.

Certain library implementations may define additional macro constants in <fenv.h> to identify additional floating-point exceptions (with their corresponding macros also beginning with FE_).

See math_errhandling for more details.

Example:

The below example shows the usage of FE_ALL_EXCEPT macro.

#include <stdio.h>
#include <fenv.h>
#include <float.h>
#include <math.h>

#pragma STDC FENV_ACCESS ON

//volatile not needed if FENV_ACCESS is supported
volatile double zero = 0.0; 
volatile double three = 3.0; 

void FE_Exceptions_Message(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 (){
  printf("1/0.0 = %f\n", (1/zero));
  FE_Exceptions_Message();

  printf("1.0/3.0 = %f\n", (1.0/three));
  FE_Exceptions_Message();

  printf("sqrt(-1.0) = %f\n", sqrt(-1));
  FE_Exceptions_Message();

  printf("DBL_MAX*2 = %f\n", (DBL_MAX*2));
  FE_Exceptions_Message();

  printf("nextafter(DBL_MIN/pow(2.0,52),0.0) = %f\n", 
      nextafter(DBL_MIN/pow(2.0,52),0.0));
  FE_Exceptions_Message();
  return 0;
}

The output of the above code will be:

1/0.0 = inf
Exceptions raised: FE_DIVBYZERO
1.0/3.0 = 0.333333
Exceptions raised: FE_INEXACT
sqrt(-1.0) = -nan
Exceptions raised: FE_INVALID
DBL_MAX*2 = inf 
Exceptions raised: FE_INEXACT FE_OVERFLOW
nextafter(DBL_MIN/pow(2.0,52),0.0) = 0.000000
Exceptions raised: FE_INEXACT FE_UNDERFLOW

❮ C <fenv.h> Library