int fesetenv( fenv_t* envp );

#include 
#include 
#include 
#pragma STDC FENV_ACCESS ON
using namespace std;

void print_exceptions()
{
    cout << "Raised exceptions: ";
    if(fetestexcept(FE_ALL_EXCEPT))
    {
        if(fetestexcept(FE_DIVBYZERO))
            cout << "FE_DIVBYZERO ";
        if(fetestexcept(FE_INEXACT))
            cout << "FE_INEXACT ";
        if(fetestexcept(FE_INVALID))
            cout << "FE_INVALID ";
        if(fetestexcept(FE_OVERFLOW))
            cout << "FE_OVERFLOW ";
        if(fetestexcept(FE_UNDERFLOW))
            cout << "FE_UNDERFLOW ";
    }
    else
        cout << "None";

    cout << endl;
}

void print_current_rounding_direction()
{
    cout << "Current rounding method: ";
    switch (fegetround()) {
        case FE_TONEAREST:
            cout << "FE_TONEAREST";
            break;
        case FE_DOWNWARD:
            cout << "FE_DOWNWARD";
            break;
        case FE_UPWARD:
            cout << "FE_UPWARD";
            break;
        case FE_TOWARDZERO:
            cout << "FE_TOWARDZERO";
            break;
        default:
            cout << "unknown";
    };
    cout << endl;
}

void print_environment()
{
    print_exceptions();
    print_current_rounding_direction();
}

int main(void)
{
    cout << "Initial environment " << endl;
    print_environment();
    fenv_t envp;

    /* Save current environment */
    fegetenv(&envp);
    feraiseexcept(FE_INVALID|FE_DIVBYZERO);
    fesetround(FE_DOWNWARD);
    cout << "After changing environment " << endl;
    print_environment();

    /* Restores previous environment */
    fesetenv(&envp);
    cout << "Restoring initial environment " << endl;
    print_environment();
    return 0;
}

Initial environment
Raised exceptions: None
Current rounding method: FE_TONEAREST
After changing environment
Raised exceptions: FE_DIVBYZERO FE_INVALID
Current rounding method: FE_DOWNWARD
Restoring initial environment
Raised exceptions: None
Current rounding method: FE_TONEAREST