Kevin Trethewey

Software Developer, Technologist, Connoisseur of things that go 'bing'.

Exceptional Quiz

Published Sunday, May 09, 2004 8:44 AM

What is the functional difference between the two catch block below?
(There's only one difference)


catch (Exception ex)

{

      throw ex;

}

catch (Exception ex)

{

      throw;

}

If you you know (or are brave enough to admit you are stumped), post in the comments section!

by Kevin Trethewey

# Colin said on Sunday, May 09, 2004 10:59 AM: I can't say that I knew that you can use throw by itself in a catch block, but looking at the code, it will generate a warning about unused variables when you compile it.

catch (Exception)
{
throw;
}

will avoid the warning.
# senkwe said on Sunday, May 09, 2004 11:05 AM: If the second statement actually compiles, I'd wager that the two statements are functionally equivalent. I say that because it would be in the language designers best interests to make sure some kind of sensible excpetion is thrown :-) Interesting.
# Mike Groenewald said on Sunday, May 09, 2004 4:05 PM: the lower catch block will not reset the call stack.
# Colin said on Sunday, May 09, 2004 6:02 PM: That's some pretty sneaky stuff...is it documented anywhere? I had a quick look in msdn and didn't see it.

I suppose it's there so that you can preserve the stack trace and still have a finally clause.
# KevinT said on Monday, May 10, 2004 8:25 AM: Mike's got it :-P Well done - u get the...um....ForestBlog Wood of the Week award!
# Armand du Plessis said on Monday, May 10, 2004 8:46 AM: Agree with Mike, second statement will preserve the call stack.