Catch two exceptions in the same catch block?

Question

I have a method that can throw two different exceptions, CommuncationException and SystemException. In both cases I do the same three-line code block.

try {  ... }  catch (CommunicationException ce) {    ... }  catch {SystemExcetion se) {    ...  } 

Is there any possibility to do it like that?

try {    ... }  catch (CommunicationException ce, SystemException se) {    ... } 

Then I would not have to write this much code. I know I could extract the exception handling to a private method, but since the code is only 3 lines long, the method definition would take more code than the body itself.

Answer 1

If you can upgrade your application to C# 6 you are lucky. The new C# version has implemented Exception filters. So you can write this:

catch (Exception ex) when (ex is CommunicationException || ex is SystemException) {     //handle it } 

Some people think this code is the same as

catch (Exception ex) {                     if (ex is CommunicationException || ex is SystemException) {         //handle it     }     throw; } 

But it´s not. Actually this is the only new feature in C# 6 that is not possible to emulate in prior versions. First, a re-throw means more overhead than skipping the catch. Second, it is not semantically equivalent. The new feature preserves the stack intact when you are debugging your code. Without this feature the crash dump is less useful or even useless.

See a discussion about this on CodePlex. And an example showing the difference.

Answer 2

In fact, you could catch only SystemException and it would handle CommunicationException too, because CommunicationException is derived from SystemException

catch (SystemException se) {    ... //this handles both exceptions }