Greetings, I have only recently begun exploring boost, and I must say that I have found it very interesting. In particular I've been focusing on boost::shared_ptr. However, I'm not quite sure how to 'deallocate' shared_ptrs that are in a Container, such as a vector. I'd like to issue some pseudocode to help put things in perspective: class Descriptor { public: bool valid; Descriptor() : valid(true) {} } struct InvalidDesc { bool operator()(Desc_ptr &d) { return (*d).valid; } }; class Desc_broker { private: vector< boost::shared_ptr< Descriptor > > desc_list; public: //These functions are, in this order, called elsewhere: void fun_1() { <conditionally invalidate Descriptors> }; void fun_2() { <iterate through desc_list and do stuff> }; void cleanup() { desc_list.erase( remove_if(desc_list.begin(), desc_list.end(), InvalidDesc()), desc_list.end() ); } }; There is the class 'Descriptor' that is contained within a shared_ptr, which is wrapped in the 'Desc_broker' class. Once a Descriptor is invalidated, such as in fun_1() above, it is no longer needed. I'll need to get rid of invalid Descriptors before the vector is iterated through in fun_2(). However, since the shared_ptr for the invalid Descriptor will not go out of scope, to the best of my knowledge I'll need to help it along by using something along the lines of 'cleanup', which will remove all desc_ptrs whose Descriptors are invalid (via std::remove_if and the InvalidDesc predicate). However, this feels wrong to me because it seems like it is against what shared_ptrs are trying to accomplish. And, in fact, Boost agrees--I receive this on cleanup(): assertion "px != 0" failed: file "/usr/local/include/boost/shared_ptr.hpp", line 253 Aborted (core dumped) What is the correct way to remove the invalid Descriptors? Also, I apologize if this is considered the unacceptable topic "Requests for help interpreting the C++ standard." If that is the case, please tell me so that I may not offend in future posts. Thank you, Jeremy Hill