FEUPDATEENV(3) Library Functions Manual FEUPDATEENV(3)

feupdateenv — update floating-point environment

#include <fenv.h>

int feupdateenv(const fenv_t *envp);

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 IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.

The feupdateenv () function shall attempt to save the currently raised floating-point exceptions in its automatic storage, attempt to install the floating-point environment represented by the object pointed to by envp, and then attempt to raise the saved floating-point exceptions. The argument envp shall point to an object set by a call to feholdexcept(3) or fegetenv(3), or equal a floating-point environment macro.

The feupdateenv () function shall return a zero value if and only if all the required actions were successfully carried out.

No errors are defined.

The following example shows sample code to hide spurious underflow floating-point exceptions:

#include <fenv.h>
double f(double x)
{
    #pragma STDC FENV_ACCESS ON
    double result;
    fenv_t save_env;
    feholdexcept(&save_env);
    // compute result
    if (/* test spurious underflow */)
    feclearexcept(FE_UNDERFLOW);
    feupdateenv(&save_env);
    return result;
}

None.

None.

None.

fegetenv(3), feholdexcept(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), <fenv.h>

First released in Issue 6. Derived from the ISO/IEC 9899:1999 (“ISO C99”) standard.

ISO/IEC 9899:1999 (“ISO C99”) standard, Technical Corrigendum 1 is incorporated.

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January 1, 2004 posix.fail