title: How to clear stdin before getting new input?
body: <p>I have read about 5-10 different advices how to clear stdin, but none of them suits my needs. The thing is that <code>fflush(stdin)</code> worked perfectly at my computer, but unfortunately it doesn't seem to work everywhere, so I need something with the same functionality. Every other way I tried clears stdin when it is not empty but requires user input when stdin IS empty, which means it requires input in a moment I dont want to get any (+ it discards it anyway).</p>
  
  <p>The question is: Can I somehow make sure, that <code>stdin</code> IS empty before I require user input? (and if not, THEN and only then clear it somehow?)
  something like: </p>
  
  <pre><code>if (stdin is NOT empty) 
      while (getchar() != '\n')
          continue;
  </code></pre>
  
  <p>EDIT: the thing is that I load characters from <code>stdin</code> one by one and at some point, a part of the input from previous iteration might or might not get discarded. either way, I need to have clear <code>stdin</code> before I ask the user for another input to be processed. Clearing the buffer itself is not such a big deal, the problem is what happens when the input is empty when the program gets to the point of clearing <code>stdin</code>, because in that moment the program needs another input which is going to be eaten by the clearing function. Thats what I want to get rid of. (when I could use <code>fflush(stdin);</code> I just knew, that for the next line of my program the <code>stdin</code> WILL be empty no matter what, no questions asked...)</p>