Programming

#include <stdio.h>
#include <signal.h>

void showspin(void)     // Shows a different charcter every time its called
{
        static char *spin="-/|\\", pos=0;
        if(!spin[++pos]) pos=0; // If we hit the NULL terminator, skip to beginning of string
        // We have to use stderr, so it doesn't buffer, since we're not printing a newline
        fprintf(stderr,"%c\r",spin[pos]); // Show character at position 'pos' in string
}

void dospin(int sig)    // Starts showing spinner repeatedly
{
        showspin();
        signal(SIGALRM, dospin); // Register this function to be called on SIGALRM
        alarm(1); // Cause SIGALRM to happen 1 second later
}

void nospin()           // Cancels the spinner
{
        alarm(0);
        fprintf(stderr," \r"); // Erase the spinner
}

int main(void)
{
        int n;
        dospin(SIGALRM);
        for(n=1; n<(1000*1000*2000); n++);
        nospin();
}