Call function periodically without using threads and sleep() method in c

Question

I want to call a function, lets say every 10 or 20 seconds. When I searched, I came up with threads and sleep() method everywhere.

I also checked for time

Answer 1

Simple:

#include 
#include 

int main(int argc, const char** argv)
{
    while(1)
    {
        usleep(20000) ;
        printf("tick!\n") ;
    }
}

Note that usleep() will of course block :)