Try, Catch & Throw

[drpraveen]

Hi!

I have a problem regarding try, catch and throw statements.....

After catching all exceptions with a catch(...) statement, I need to determine the type of the exception. Whether it is a CDBException or a CMemoryException or something else. How can I do this? I am trying to implement the following scenario across many functions:


try
{
// Processing code
}
catch(...)
{
// Do cleanup

// Rethrow a user defined exception class, for
// which I need to know the type of the exception
}




I can handle individual exceptions but it will result in the duplication of cleanup code.

looking forward to any suggestions,

Regards,
Praveen

If the object being thrown is derived from CException (which it should be) you can use the CObject::IsKindOf() method to find out the type of object. The CException class will require either an IMPLEMENT_DYNAMIC or an IMPLEMENT_SERIAL method, but you can then use the following syntax:

if (pObj->IsKindOf( RUNTIME_CLASS(MyExceptionClass) ))

You can also test against CMemoryException, CFileException, and so on...

Cheers!
Humble Programmer
,,,^..^,,,

[Franky Braem]

You can use typeid function for this.

example :
if ( typeid(*exception) == typeid(CDBException) )
{
// this is a CDBException
}
else
{
// Another exception
}



Note that the typeid test only verifies that an object is exactly of a certain class ("is a").
In order to verify the compatibility ("is kind of"), the dynamic_cast operation must be used.
This only works on polymorphic classes (at least one virtual member)

Hope this helps.