title: C# array of objects - conditional validation
body: <p>Sorry about the vague title!</p>
  
  <p>I have an class with a number of member variables (system, zone, site, ...)</p>
  
  <pre><code>public sealed class Cello
  {
      public String Company;
      public String Zone;
      public String System;
      public String Site;
      public String Facility;
      public String Process;
      //...
  }
  </code></pre>
  
  <p>I have an array of objects of this class.</p>
  
  <pre><code>private Cello[]   m_cellos = null;
  // ...
  </code></pre>
  
  <p>I need to know whether the array contains objects with the same site but different systems, zones or companies since such a situation would be illegal. I have various other checks to make but they are all along similar lines.</p>
  
  <p>The Array class has a number of functions that look promising but I am not very up on defining 'key selector' functions and things like that.</p>
  
  <p>Any suggestions or pointers would be greatly appreciated.</p>
  
  <p>--- Alistair.</p>