title: Determine which expression was not true in if-statement in C#
body: <p>Let's say I have the following piece of code:</p>
  
  <pre><code>infile = new FileInfo(inputFilename);
  outfile = new FileInfo(outputFilename);
  
  if (!infile.Exists || !outfile.Exists) {
    Console.WriteLine("File missing: " + ???);
  }
  </code></pre>
  
  <p>Is it possible to determine which of the single "if statements" was not true? <code>???</code> shall be replaced with the filename of the non-existing file.</p>