fetestexcept - Man Page

test floating-point exception flags


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#include <fenv.h>

int fetestexcept(int excepts);


The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2017 defers to the ISO C standard.

The fetestexcept() function shall determine which of a specified subset of the floating-point exception flags are currently set. The excepts argument specifies the floating-point status flags to be queried.

Return Value

The fetestexcept() function shall return the value of the bitwise-inclusive OR of the floating-point exception macros corresponding to the currently set floating-point exceptions included in excepts.


No errors are defined.

The following sections are informative.


The following example calls function f() if an invalid exception is set, and then function g() if an overflow exception is set:

#include <fenv.h>
/* ... */
    int set_excepts;
    feclearexcept(FE_INVALID | FE_OVERFLOW);
    // maybe raise exceptions
    set_excepts = fetestexcept(FE_INVALID | FE_OVERFLOW);
    if (set_excepts & FE_INVALID) f();
    if (set_excepts & FE_OVERFLOW) g();
    /* ... */

Application Usage




Future Directions


See Also

feclearexcept(), fegetexceptflag(), feraiseexcept()

The Base Definitions volume of POSIX.1-2017, <fenv.h>

Referenced By

acos(3p), acosh(3p), asin(3p), asinh(3p), atan(3p), atan2(3p), atanh(3p), ceil(3p), cos(3p), cosh(3p), erf(3p), erfc(3p), exp(3p), exp2(3p), expm1(3p), fdim(3p), feclearexcept(3p), fegetexceptflag(3p), fenv.h(0p), feraiseexcept(3p), floor(3p), fma(3p), fmod(3p), hypot(3p), ilogb(3p), j0(3p), ldexp(3p), lgamma(3p), llrint(3p), llround(3p), log(3p), log10(3p), log1p(3p), log2(3p), logb(3p), lrint(3p), lround(3p), nearbyint(3p), nextafter(3p), pow(3p), remainder(3p), remquo(3p), rint(3p), round(3p), scalbln(3p), sin(3p), sinh(3p), sqrt(3p), tan(3p), tanh(3p), tgamma(3p), y0(3p).

2017 IEEE/The Open Group POSIX Programmer's Manual