Exception handling

Question

hello sir/madam, could you please tell me what happens in the following session1 and session2? Section 1 Try{ Some code } Catch(exception e) { Throw e; } Section 2 Try{ Some code } Catch(exception e) { Throw; }

Niradhip Chakraborty · Answer

throw e will restart the stack trace where as 'throw' retains the original stack trace. Basically MSIL (CIL) has two instructions - "throw" and "rethrow" and guess what - C#'s "throw ex;" gets compiled into MSIL's "throw" and C#'s "throw;" - into MSIL "rethrow"! Basically I can see the reason why "throw ex" overrides the stack trace, that's quite intuitive if you think about it for a moment. But "throw" syntax for "rethrow" instruction is not really intuitive. It smells stack based MSIL, which is obviously under the cover, but actually should be kept there. I guess they wanted to keep number of C# keywords small, that's the reason. So you just better know this stuff - use "throw;" to re-throw an exception in .NET.

kalyan Bandarupalli · Answer

Hi Both are having the saming functionality. the difference comes in memory. extra stack inf'n will build when i say throw ex and extra lines will be added to the MSIL where as it is not in the throw statement.

Jan Montano · Answer

Here's a nice article

Exception handling

Answers (3)