c++ - Why don't the changes to my variables survive until the next iteration? -

i want update instances of struct storing in map within loop, changes instance variables don't survive iterations of loop (within 1 iteration, new variables set, in next operation reset initial value).

here simplified version of doing:

map<int, regionoverframes>* foundregions = new map<int, regionoverframes>;  (int = 0; < frames.size(); i++) {      // find regions in current frame     map<int, regionoverframes> regionsincurrentframe;     (region region: currentframe.regions) {         if (foundregions->count(region.regionid) == 0) {             regionoverframes foundregion;             foundregion.regionid = region.regionid;             regionsincurrentframe[region.regionid] = foundregion;             (*foundregions)[region.regionid] = foundregion;         }         else if (foundregions->count(region.regionid) > 0) {             regionoverframes foundregion = (*foundregions)[region.regionid];             regionsincurrentframe[region.regionid] = foundregion;         }     }      // update found regions (either adding weight or setting end index)     (auto = foundregions->begin(); != foundregions->end(); it++) {         regionoverframes foundregion = it->second;         // region found before present in frame         if (regionsincurrentframe.count(foundregion.regionid) > 0) {             float weight = currentframe.getregion(foundregion.regionid).getweight();             foundregion.accumulatedweight += weight; // update of accumulatedweight not present in next loop, accumulatedweight gets assigned value of weight here, in next iteration it's reset 0         }     } } 

could have fact using iterator it access objects within map<int, regionoverframes>* foundregions or fact foundregions declared pointer , stored on heap?

note regionoverframes simple struct looking this:

struct regionoverframes {    int regionid;    double accumulatedweight; } 

your issue creating copy of found region rather updating object found in map.

regionoverframes foundregion = it->second; //               ^ copy created 

you should use references instead:

regionoverframes &foundregion = it->second; //               ^ use reference