RE: [Boost-users] newbie question about boost::regex and memory leaks

From: Ben Hutchings (ben.hutchings_at_[hidden])
Date: 2004-02-03 11:20:46

Gregory, Matthew <matt.gregory_at_[hidden]> wrote:
> Forgive the likely simple question ...
> 
> I am using boost-1.30.2 regex library in a C++ console app and have
> been using VC7 to debug memory leaks through the _CrtDumpMemoryLeaks()
> function.

Where is this called from?

> It reports numerous memory leaks on the first time I use a
> boost::regex object, albeit relatively small leaks.  For example, if I
> use
> 
> boost::regex statsRe("^\\s+8\\s+ENVI\\s+AX4.*")
> 
> there are a number of memory leaks from memory allocated in the
> boost::re_detail::w32_traits_base::do_init() block.
> 
> I am wondering if I am doing something wrong in that no destructor
> gets called for these objects or if small memory leaks are to be
> expected when using these objects.

The only memory allocation I can see is for the array that pclasses
points to and the strings in it.  These are freed in do_free() which is
called by the destructor of the last instance of w32_traits_base. 
Since each of the derived classes of w32_traits_base
(w32_regex_traits<char> and w32_regex_traits<wchar_t>) has a static
instance of itself as a member, the memory will not be freed until after
main() returns.  So if you call _CrtDumpMemoryLeaks() at the end of
main() this memory will wrongly be reported as leaked.