C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  delete the dynamic memory buffer ststream is mapped to          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Luke Guest Posted: Sat Dec 23, 2006 4:47 am    Post subject: delete the dynamic memory buffer ststream is mapped to Hi all, I know about the fact that strstream has been deprecated and that it is difficult to manage safely (esp. the str() with a following mandatory freeze(0)). Having to maintain a rather large portable library that has been around for a few years, I discovered an issue, however, using the HP C++ compiler version V7.2-018 on OpenVMS IA64 V8.3. strstream, unlike stringstream, can easily be mapped to a memory buffer - ok, deprecated, but handy and the general approach is that I need to change existing code as little as possible while maintaining portability. Following code works fine after compilation on Win32 (VC6/VC7/VC8), Linux and OpenVMS Alpha. It crashes however on IA64 (see above for the exact configuration) when executing "delete os;". When I comment out "delete rdbuf();" the code works fine again on all platforms but I get a serious memory leak on all of them. Hence my question: how can I properly clean up in a portable way? int aSize = 4096; ostream* os = new ostream(new strstreambuf(aSize)); *os << "Hello world"; // ... os->rdbuf()->freeze(0); delete rdbuf(); delete os; Kindest regards, Luc Vervoort -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Thomas Maeder Guest Posted: Sun Dec 24, 2006 1:14 am    Post subject: Re: delete the dynamic memory buffer ststream is mapped to "Luke" <lcvervoort (AT) yahoo (DOT) com> writes: Quote: It crashes however on IA64 (see above for the exact configuration) when executing "delete os;". When I comment out "delete rdbuf();" the code works fine again on all platforms but I get a serious memory leak on all of them. Hence my question: how can I properly clean up in a portable way? int aSize = 4096; ostream* os = new ostream(new strstreambuf(aSize)); I'd start with strstreambuf buf(aSize); ostream os(&buf); .. This will already eliminate two of the possible ways of leaking memory. -- [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Frederic Lachasse Guest Posted: Sun Dec 24, 2006 1:16 am    Post subject: Re: delete the dynamic memory buffer ststream is mapped to "Luke" <lcvervoort (AT) yahoo (DOT) com> wrote in message news:1166802599.526964.140440 (AT) h40g2000cwb (DOT) googlegroups.com... Quote: Hi all, I know about the fact that strstream has been deprecated and that it is difficult to manage safely (esp. the str() with a following mandatory freeze(0)). Having to maintain a rather large portable library that has been around for a few years, I discovered an issue, however, using the HP C++ compiler version V7.2-018 on OpenVMS IA64 V8.3. strstream, unlike stringstream, can easily be mapped to a memory buffer - ok, deprecated, but handy and the general approach is that I need to change existing code as little as possible while maintaining portability. Following code works fine after compilation on Win32 (VC6/VC7/VC8), Linux and OpenVMS Alpha. It crashes however on IA64 (see above for the exact configuration) when executing "delete os;". When I comment out "delete rdbuf();" the code works fine again on all platforms but I get a serious memory leak on all of them. Hence my question: how can I properly clean up in a portable way? int aSize = 4096; ostream* os = new ostream(new strstreambuf(aSize)); *os << "Hello world"; // ... os->rdbuf()->freeze(0); delete rdbuf(); delete os; You should delete the streambuf *after* deleting the os. In your code, the ostream does not know you have deleted its streambuf, so any maintenance task it needs to do will have undefined behaviour (using a deleted object). And AFAIK, the deprecated status of strstream has been removed in the recent revision of the C++ standard, as people found out that in some cases, strstream was more efficient. -- Frédéric Lachasse - ECP86 [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. 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