Question

From googling around it looks like Xcode (3.1 in my case) should be at least trying to give me a sane debug view of STL containers – or at least vectors.

However, whenever I go to look at a vector in the debugger I just see M_impl, with M_start and M_finish members (and a couple of others) – but nothing in-between! (it’s a debug build, btw).

Am I missing a setting or something somewhere?

I’ve also read that there are macros available that can augment the debug viewer even further to inspect more complex containers – but have been unable to find any.

I’d also like to be able to view std::wstrings, without having to drop to the memory viewer. It shows std::string fine. Is there anything I can do to show std::wstring?

I realise this is a bit of a composite question – but it’s all really part of the same subject.

Answer 1

The ability to view the container’s items may rely on the complexity of the templated type. For trivial objects like int, bool, etc., and even simple class templates like

template <class T> struct S { T m_t; } 

I normally have no problem viewing vector items in the debugger variable view. I say normally because there seem to be occasional bugs that cause stuff–particularly when debugging–not to behave the way I expected. One of those things is garbage or totally useless information in the variable view. Usually a clean rebuild of the target (or sometimes even a more drastic restarting of XCode followed by a clean rebuild) fixes the problem.

As for the other container types, it’s most likely hard to efficiently view this information. For example a map is often implemented as a red-black tree. The debugger would have to know that in advance in order to properly walk the tree and show you all the keys and values. That’s probably asking a lot from Xcode or GDB–especially since the former focuses more on Objective-C and plain C than C++ (hence the fact that namespaces tend to kill code completion despite their ubiquity and importance).