signal handler function in c program

signal_handler.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>

volatile sig_atomic_t please_stop;

void handler_sigint()
{
    please_stop = 1;
}

int main(int argc, char const *argv[])
{
    printf("%d \n", getpid());
    signal(SIGINT, handler_sigint);
    while (please_stop == 0)
    {
        sleep(1);
        write(1, ".", 1);
    }
    if (please_stop == 1)
    {
        write(1, "clean !!!", 10);
    }

    return 0;
}