Catch vs Catch (Exception e) and Throw vs Throw e

Question

Are these two code examples the same? Catch and Catch (Exception e) have the same output, and the result is also the same if I write

Answer 1

If we ignore the "unused variable" warning, the only time there is a practical difference between

catch {...}

and

catch(Exception ex) {...}

is when some non-C# code is throwing a non-Exception exception. C++ can throw anything. In .NET 1.1, you had to use catch (no (Exception ex)) to handle these unusual exceptions. However, this was problematic - not least, you can't see what was thrown! So in .NET 2.0 and above this is wrapped by default, so even if C++ throws, say, a string - you see it as an Exception subclass. Note that this can be disabled via a configuration setting, but: don't. Leave it alone!

The issue of throw; vs throw ex; is already mentioned, and relates to stack-traces. You can use throw in both cases, causing the original stack-trace to be preserved.