Hello Joaquin, I have a class like below that uses mult-index container's find method.  I have a record pattern as below initially: Idx : 100 Flag : 5 Idx : 200 Flag : 5 Idx : 300 Flag : 5 Idx : 400 Flag : 5 I modify the flag for index 100 to 6 & take a dump, the change is OK Idx : 100 Flag : 6 Idx : 200 Flag : 5 Idx : 300 Flag : 5 Idx : 400 Flag : 5 I modify the flag for 100 back to 5 and take a dump, which is also fine. Idx : 100 Flag : 5 Idx : 200 Flag : 5 Idx : 300 Flag : 5 Idx : 400 Flag : 5 Now I do a find based on flag value set to 5 I get the results as below: Idx : 200 flag : 5 While find functionally is correct in picking up the correct data, but I am wondering why it doesnt pick the first record (100) which has the flag value set to 5? am I missing something in the indexing definition in the container itself? Thanks /R ========================= using namespace std; #include <boost/lambda/lambda.hpp> #include <boost/multi_index_container.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/member.hpp> #include <iostream> #include <iterator> #include <iostream> #include <string> struct Token { unsigned long  mIdx; unsigned char mflag; public:        Token(unsigned long pIdx, unsigned char pflag):                            mIdx(pIdx), mflag(pflag){}        void Update(unsigned char pflag) {             mflag = pflag;        }        ~Token() {            mIdx =  0;            mflag = 1;        } }; struct mIdx{}; struct mflag{}; using namespace boost::multi_index; namespace ll = boost::lambda; typedef multi_index_container<  Token,    indexed_by<        ordered_unique<            tag <mIdx>, BOOST_MULTI_INDEX_MEMBER(Token,unsigned long,mIdx)>,        ordered_non_unique<            tag <mflag>, BOOST_MULTI_INDEX_MEMBER(Token,unsigned char,mflag)>    >

tToken;

class TokenMaster {    tToken TokenContainer; public:  unsigned long getByFlag(unsigned long useFlag);  bool modify(unsigned long idx, unsigned char flag);  bool insert(unsigned long, unsigned char);  void dump(); }; unsigned long TokenMaster::getByFlag(unsigned long useFlag) {    typedef tToken::index<mflag>::type itflag;    itflag& mflag_index = TokenContainer.get<mflag>();    tToken::index_iterator<mflag>::type flagit = mflag_index.find(useFlag);    if (flagit == mflag_index.end()) {        return 0;    }    printf("Idx : %d flag : %d\n", flagit->mIdx, flagit->mflag);    return flagit->mIdx; } bool TokenMaster::modify(unsigned long idx, unsigned char flag) {    tToken::iterator itIp=TokenContainer.find(idx);    if (itIp == TokenContainer.end())        return false;    return TokenContainer.modify(itIp,(&ll::_1)->*&Token::mflag=flag); } bool TokenMaster::insert(unsigned long idx, unsigned char flag) {    tToken::iterator it;    bool secres;    std::pair<tToken::iterator, bool> result =                    TokenContainer.insert(Token(idx, flag));    it = result.first;    secres = result.second;    if (secres)        return true;    else        return false; } void TokenMaster::dump() {    unsigned long count = 0;    printf("\n\n List of indexes\n");    for (tToken::iterator it = TokenContainer.begin(),        it_end=TokenContainer.end(); it != it_end; ++it, count++)    {        printf("Idx : %d Flag : %d\n", it->mIdx, it->mflag);    }    printf("\n"); } main() {  TokenMaster T1;  T1.insert(100, 5);  T1.insert(200, 5);  T1.insert(300, 5);  T1.insert(400, 5);  T1.dump();  printf("Modifiying 100 to 6\n");  T1.modify(100, 6);  T1.dump();  printf("Modifiying 100 back to 5\n");  T1.modify(100, 5);  T1.dump();  printf("\n\nGet by flag \n");  T1.getByFlag(5); } ==========================