Hello. I am using projection technique & modify_key in one of my member functions: Assuming I have the following data in the container: ObjId ObjIp ObjIndex pMyObj ------------------------------------------------------------------------------------- ID1 10.10.1.2 1 0x10239032 ID2 10.10.1.3 2 0x23423423 ID3 10.10.1.4 3 0x23132423 The member function 'UpdateKeyObjId' accepts the value on column 3 as key & changes the corresponding value for the field in Column 1. My code seems to work fine for all rows except the last row. When I use modify key on the last record, the app crashes at the highlighted line. I am not sure if my usage of project & modify_key right, could someone please point out if there are any errors in the usage? Thanks /R struct MyMap { std::string ObjId; unsigned long ObjIp; unsigned long ObjIndex; MyObj *pMyObj; MyMap(std::string param_ObjId, unsigned long param_ObjIp, unsigned long param_ObjIndex, MyObj* param_pMyObj): ObjId(param_ObjId), ObjIp(param_ObjIp), ObjIndex(param_ObjIndex), pMyObj(param_pMyObj) {} ~MyMap(){ ObjId.erase(); ObjIp = 0; ObjIndex = 0; pMyObj = 0; } }; struct ObjId{}; struct ObjIp{}; struct ObjIndex{}; typedef multi_index_container< MyMap, indexed_by< ordered_unique< tag <ObjId>, BOOST_MULTI_INDEX_MEMBER(MyMap,std::string,ObjId)>, ordered_non_unique< tag<ObjIp>,BOOST_MULTI_INDEX_MEMBER(MyMap,unsigned long,ObjIp)>, ordered_unique< tag<ObjIndex>,BOOST_MULTI_INDEX_MEMBER(MyMap,unsigned long,ObjIndex)> >

tMyObjMap;

class MyObjContainer{ private: tMyObjMap MyContainer; public: UpdateKeyObjId(unsigned long, std::string); }; bool MyObjContainer::UpdateKeyObjId(unsigned long param_ObjIndex, std::string param_ObjId) { typedef tMyObjMap::index<ObjIndex>::type tMyObjMapByIndex; tMyObjMapByIndex& ObjIndex_index = MyContainer.get<ObjIndex>(); tMyObjMap::index_iterator<ObjIndex>::type it = ObjIndex_index.find(param_ObjIndex); typedef tMyObjMap::index<ObjId>::type tMyObjMapById; tMyObjMapById::iterator ObjIdit = MyContainer.project<0>(it); // Use the modify_key method to update the ObjIp key with new value return MyContainer.get<0>().modify_key(ObjIdit, ll::_1 = param_ObjId); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ }