为什么抛出的异常与catch块C＃没有正确匹配

Question

Facing some weird issue with SocketException. Attached screenshot speaks more about it.

1. Why first catch block is not catching the exception while it is meant to catch the SocketException and thrown exceptions is again a SocketException.

2. Why control is going to second catch block which is meant to catch any exception ?

[Edit] : Adding screenshot in debug mode too

Answer 1

Execution is not entering the second catch block, try-catch obviously doesn't work that way, the exception is thrown up the call stack, any following catch clauses are ignored.

It simply looks that way because you are debugging in Release mode which is not a good idea as the IDE is probably missing important debugging information and is therefore erroneously showing that execution halts when entering the second catch clause.

Do notice that halting at that point really makes no sense, if execution somehow made it into the second catch clause it would halt at the throw statement, not before.

To make it short, what's really going on is that execution is halting on the first throw and the IDE is not showing it correctly.

Moral of the story; do not debug in Release mode. If you are running VS2015 it actually warns you that debugging experience in Release mode will be subpar (not sure if this warning appeared in previous versions).

UPDATE : It seems the issue is not related to debugging in Release mode as it still happens in Debug mode. Still, the point stands that debugging shouldn't be done in Release mode as funky stuff like this can happen. I would try cleaning the solution and see if that solves the problem. If it doesn't I wouldn't sweat it, the code is behaving correctly, its just a matter of the IDE not showing correctly where the execution is halting, no big deal.