What is the recommended way to catch exceptions

Question

I have to do a code review and i got to a code part that addresses possibles exceptions. it looks to me that the developer coding works but i want to ask what is the usual and correct way to do that. What is the best way to do catch exceptions? the coder wrote:

  try 
  { . . . }
  catch (Exception ex)
  {
    if (ex is PlatformNotSupportedException)
    { //for the Windows version or edition that does not support.
    // tracing
    }
    else if (ex is NotSupportedException || ex is IOException)
    { // for the NTFS not supported or EFS is not configured
      // tracing
    }
    else
    {
      //report any exception as encrypt/decrypt
    }
  }

I thought that the book says that it should be:

  catch (PlatformNotSupportedException pnse)
  {
    //for the Windows version or edition that does not support.
    // tracing
  }
  catch (NotSupportedException nse)
  {
    // for the NTFS not supported or EFS is not configured
    // tracing
  }
  catch (IOException ioe)
  {
    // tracing for IOE
  }   
  catch (Exception e)
  {
      //report any exception as encrypt/decrypt
  }

Answer 1

The second approach would be more preferred. However, there is tiny difference between proposed solution and current one. You'd need to refactor to a method, or copy the code in two places (NotSupportedException and IOException catch blocks), whilst current implementation handles it under the same if block.

So, if you want to follow the same approach, you can use when keyword to filter out certain types and more.

  catch (PlatformNotSupportedException pnse)
  {
    // for the Windows version or edition that does not support.
    // tracing
  }
  catch (Exception ex) when (ex is NotSupportedException || ex is IOException)
  {
    // for the NTFS not supported or EFS is not configured
    // tracing
  } 
  catch (Exception e)
  {
      //report any exception as encrypt/decrypt
  }

If that's not mandatory, you can leave implementation as is