title: printf gives WARNING only
body: <p>Can anyone tell me why <em>not</em> including <code>stdio.h</code> and still using the <code>printf</code> function only gives a warning on gcc?</p>
  
  <blockquote>
    <p>warning: incompatible implicit declaration of built-in function ‘printf’</p>
  </blockquote>
  
  <p>Rather this should be a compile error, as we are including a function that is not declared.</p>
  
  <p>Does this have something to do with the linking procedure? Please elaborate.</p>