Question

In C++, what is the difference between the following examples?

Re-throw pointer:

catch (CException* ex)
{
    throw ex;
}

Simple re-throw:

catch (CException* ex)
{
    throw;
}

When the re-throw is caught, will the stack trace be different?

Answer 1

Yes. Basically, you are throwing the object yourself in the first case. It looks like you generated the exception yourself in the throw ex line. In the second case, you are just letting the original object go up in the call stack (and thus preserving the original call stack), those are different. Usually, you should be using throw;.