Hi, all, I'm a fresh hand to boost. I encounter some problems with ptr_map, in boost/ptr_container/detail/associative_ptr_container.hpp, line 107 & 111. size_type erase( const key_type& x ) // nothrow { BOOST_ASSERT( !this->empty() ); iterator i = find( x ); // nothrow // line 107 if( i == this->end() ) // nothrow return 0; // nothrow this->remove( i ); // nothrow return this->c_private().erase( i.base() ); // nothrow // line 111 } In fact I doubt the correctness of these two lines. First, find() is defined in ptr_map_adapter class, which is a descendant of associative_ptr_container. No other find() functions could match the case here. As for the erase() in line 111, it's actually std::map::erase(). But this overload should return nothing as specified in C++ standard (in the case of MS implementation, it returns an iterator). In no way can it be converted to size_type. Simple modifications on the code could solve this problem. Another thing for ptr_map_adapter is one of its Insert() overloads std::pair insert( key_type& key, value_type x ) I wonder why we don't use const key_type&? Without const modifier, the compiler would not allow passing constants to it. At last, never forget to mention my environment: VC 8.0 No test has been done in other environment. -- Jason