title: Compare two text files line by line, finding differences
body: <p>I'm trying to find the fastest way to compare two text files line by line, combining the results in a single multidimensional array with flags for the differences, e.g.:</p>
  
  <pre><code>array(0) (line1) (in file a) (in file b)
  array(1) (line2) (in file a) (not in file b)
  array(2) (line3) (not in file a) (in file b)
  </code></pre>
  
  <p>I know how to write my own code for this but it's slow, so I wonder if there is some kind of .NET method that's faster? Currently working in VS2008 .NET 3.5, but will probably move project to VS2013/15, so whatever framework that does the job best will do.</p>