title: string.find() returns true when ==-1 is used but false when <0 is used
body: <p>I am trying to find a character within a string but I am getting unexpected results. My understanding is that <code>string::find(char c)</code> returns <code>-1</code> when it is not found. However, I am getting some unexpected results. </p>
  
  <p>Even though the string does not include an <code>'8'</code>, it is still returning <code>true</code>.</p>
  
  <pre><code>std::string s = "123456799";
  if(s.find('8')&lt;0)
      cout &lt;&lt; "Not Found" &lt;&lt; endl;
  else
      cout &lt;&lt;  "Found" &lt;&lt; endl;
  
  //Output: Found
  </code></pre>
  
  <p>However, when using <code>==</code> instead the code works as expected.</p>
  
  <pre><code>std::string s = "123456799";
  if(s.find('8')==-1)
      cout &lt;&lt; "Not Found" &lt;&lt; endl;
  else
      cout &lt;&lt;  "Found" &lt;&lt; endl;
  
  //Output: Not Found
  </code></pre>