title: C# Sequential file output
body: <p>I have a <code>C# winform</code> application that is outputting to excel files.
  Let's say the name format of the file name is: <code>Output1.xlsl</code></p>
  
  <p>I would like to have the output saved to another sequential file on each button click/execution.
  So next it would be <code>Output2.xlsl</code>, <code>Output3.xlsl</code>... etc.</p>
  
  <p>How to check that, I know of checking if the file exists, but how to check for the numbering?</p>
  
  <pre><code>FileInfo newExcelFile = new FileInfo(@"Output1.xlsx");
  if (newExcelFile.Exists)
  {
        ...
  }
  </code></pre>