title: Call function periodically without using threads and sleep() method in c
body: <p>I want to call a function, lets say every 10 or 20 seconds. When I searched, I came up with threads and <code>sleep()</code> method everywhere. </p>
  
  <p>I also checked for time and clock classes in C but I could not find anything helpful specific to my question.</p>
  
  <p>What is the most simple way to call functions periodically?</p>