std::feclearexcept(3)

okay bestie, welcome to the std::feclearexcept(3) page from the C++ Standard Libary manual 💅✨ this is the one about clearing floating-point exception flags, and it’s giving very “tiny function, big fenv energy” 🦋

🌸 NAME 🌸

std::feclearexcept - std::feclearexcept — yes bestie, the name is just the name, iconic 💖

✨ Synopsis ✨

Defined in header <cfenv>
int feclearexcept( int excepts );  (since C++11)

What it does: it attempts to clear the floating-point exceptions that are listed in the bitmask argument excepts — and that bitmask is a bitwise OR of the floating point exception macros 🌈

🎀 Parameters 🎀

• excepts — bitmask listing the exception flags to clear.

💖 Return value 💖

• 0 if all indicated exceptions were successfully cleared or if excepts is zero.
• Returns a non-zero value on error.

🦋 Example 🦋

run this code, bestie 😭✨

#include <cfenv>
#include <cmath>
#include <iostream>

// #pragma STDC FENV_ACCESS ON

volatile double zero = 0.0; // volatile not needed where FENV_ACCESS is supported
volatile double one = 1.0;  // volatile not needed where FENV_ACCESS is supported

int main()
{
    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout <<  "1.0/0.0 = " << 1.0 / zero << '\n';
    if (std::fetestexcept(FE_DIVBYZERO))
        std::cout << "division by zero reported\n";
    else
        std::cout << "division by zero not reported\n";

    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "1.0/10 = " << one / 10 << '\n';
    if (std::fetestexcept(FE_INEXACT))
        std::cout << "inexact result reported\n";
    else
        std::cout << "inexact result not reported\n";

    std::feclearexcept(FE_ALL_EXCEPT);
    std::cout << "sqrt(-1) = " << std::sqrt(-1) << '\n';
    if (std::fetestexcept(FE_INVALID))
        std::cout << "invalid result reported\n";
    else
        std::cout << "invalid result not reported\n";
}

Possible output:

1.0/0.0 = inf
division by zero reported
1.0/10 = 0.1
inexact result reported
sqrt(-1) = -nan
invalid result reported

🌈 See also 🌈

• fetestexcept — determines which of the specified floating-point status flags are set (C++11) (function) ✨
• C documentation for feclearexcept 🫶

mwah 💋 — this page’s source/version is http://cppreference.com, dated 2024.06.10, and the manual page is std::feclearexcept(3). byeeee, bestie 🎀