title: C# string does not contain possible?
body: <p>I'm looking to know when a string does not contain two strings.  For example.</p>
  <pre><code>string firstString = &quot;pineapple&quot;
  string secondString = &quot;mango&quot;
  
  string compareString = &quot;The wheels on the bus go round and round&quot;
  </code></pre>
  <p>So, I want to know when the first string and second string are not in the compareString.</p>
  <p>How?</p>