stlmap - C++ map not inserting properly -

i trying populate map following structs:

struct counterparty {     uint8_t firm_id;     char trader_tag[3];     uint32_t qty; }; struct orderfillmessage {     header header;     uint32_t order_id;     uint64_t fill_price;     uint32_t fill_qty;     uint8_t no_of_contras;     std::vector<counterparty> counterpartygroup;     char termination_string[8];  };  void tradedecoder::findmostactivetrader() {     map<char*,int> traders_volume_map;     for(orderfillmessage m: orderfillmessages)     {         for(counterparty cp: m.counterpartygroup)         {             outputfile<<cp.trader_tag<<" "<<cp.qty<<endl;             traders_volume_map[cp.trader_tag]+=cp.qty;         }     }     outputfiletrader<<"printing map "<<traders_volume_map.size()<<"\n";     for(auto it=traders_volume_map.begin(); it!=traders_volume_map.end(); it++)     {         outputfiletrader<<(it)->first<<(it)->second<<endl;     } } 

as can see, simple insert or update map function.

outputfile<<cp.trader_tag<<" "<<cp.qty<<endl; 

prints following:

iyh 2 htc 1 iyh 2 htc 1 iyh 2 htc 1 iyh 1 htc 1 iyh 1 htc 1 iyh 1 htc 1 iyh 1 htc 1 iyh 1 

however outputfiletrader<<"printing map "<

printing map 1 htc3050 

which means nothing added map, , found though there 1 element in map!?

any insights why happening appreciated!!

thanks

i want add that, trader_tag of char[3], not null terminated. however, not think cause map issue

you using char * key. bad idea vary considerably.

use following

map<std::string, int> traders_volume_map; 

to overcome problem.