6.5.11 feraiseexcept Function

Raises the supported floating-point exceptions represented by its argument.

Include

<fenv.h>

Prototype

void feraiseexcept(int excepts);

Argument

excepts

a value being the bitwise OR of one or more floating-point exception macros, representing the exceptions to raise

Remarks

The order in which these floating-point exceptions are raised is unspecified, except if the argument represents "overflow" and "inexact", or "underflow" and "inexact", in which case "overflow" or "underflow" is raised before "inexact".

Example

See the notes at the beginning of this chapter or section for information on using printf() or scanf() (and other functions reading and writing the stdin or stdout streams) in the example code.

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

void showExceptions(void)
{
  printf("Exceptions currently 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 ");
  printf("\n");
}

volatile double result = 0.0;

int main(void)
{
  fexcept_t excepts;

  result = 1.0 / result;                          // raise FE_DIVBYZERO
  showExceptions();
  fegetexceptflag(&excepts, FE_ALL_EXCEPT);       // save state
  feraiseexcept(FE_INVALID|FE_OVERFLOW);          // raise exceptions without operation
  showExceptions();
  fesetexceptflag(&excepts, FE_ALL_EXCEPT);       // restore state
  showExceptions();
}

Example Output

Exceptions currently raised: FE_DIVBYZERO 
Exceptions currently raised: FE_DIVBYZERO FE_INEXACT FE_INVALID FE_OVERFLOW 
Exceptions currently raised: FE_DIVBYZERO