Question

I have a function that I want to run whenever my program exits:

void foo() {
  std::cout<< "Exiting" << std::endl;
}

How do I register it to be run whenever the program exists, regardless of when and why it exits – due to signal, exit() call, etc?

Answer 1

You can use the aptly named std::atexit function in the cstdlib header:

#include <cstdlib>

void exiting() {
    std::cout << "Exiting";
}

int main() {
    std::atexit(exiting);
}

The system will maintain a stack of functions registered with atexit and call them each in the reverse order of their registration when either the exit function is called, or the program returns from main. You can register at least 32 functions this way.