title: Fixing a broken loop by changing exactly one character
body: <p>I found <a href="http://www.gowrikumar.com/c/index.html" rel="nofollow noreferrer">a site</a> with some complicated C puzzles. Right now I'm dealing with this:</p>
  
  <blockquote>
    <p>The following is a piece of C code, whose intention was to print a minus sign 20 times. But you can notice that, it doesn't work.</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  int main()
  {
      int i;
      int n = 20;
      for( i = 0; i &lt; n; i-- )
          printf("-");
      return 0;
  }
  </code></pre>
    
    <p>Well fixing the above code is straight-forward. To make the problem interesting, you have to fix the above code, by changing exactly one character. There are three known solutions. See if you can get all those three.</p>
  </blockquote>
  
  <p>I cannot figure out how to solve. I know that it can be fixed by changing <code>--</code> to <code>++</code>, but I can't figure out what single character to change to make it work.</p>