fetestexcept()

Determine which of the specified floating-point status flags are set

Synopsis:

#include <fenv.h>

int fetestexcept( const int excepts );

Arguments:

excepts
A bitwise OR of the flags that you want to check; zero or more of the following:
  • FE_ALL_EXCEPT — all the bits
  • FE_DIVBYZERO — pole error
  • FE_INEXACT — inexact result; rounding was necessary
  • FE_INVALID — domain error
  • FE_OVERFLOW — result is too large to be representable
  • FE_UNDERFLOW — result is subnormal with a loss of precision

Library:

libm

Use the -l m option to qcc to link against this library.

Description:

The fetestexcept() function determines which of the specified floating-point exceptions are currently set.

Returns:

A bitwise OR of the flags that are in excepts and that correspond to floating-point exceptions that are currently set.

Examples:

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

int main( void )
{
    int except_flags;

    /* acos(2) should raise a "range error" exception. */

    feclearexcept(FE_ALL_EXCEPT);
    printf( "acos(2) is %f\n", acos(2) );
    except_flags = fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW);
    if(except_flags & FE_INVALID)
        puts("FE_INVALID (range error) reported");

    return EXIT_SUCCESS;
}

Classification:

C99, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler No
Thread Yes