Question

Is it a feature of unordered_map::find() to insert the key that we lookup with 0 value automatically?
Let me make this clear

    unordered_map<int, int> tempMap;
    //some code
    if(tempMap.find(1) == tempMap.end()){
      //do something but not insert the 1 with a corresponding value into the tempMap
    }

so if I lookup 1 again, will it be there in the tempMap having 0 as corresponding value.
Is that a feature of unordered_map?

Answer 1

No, find only searches and returns an iterator.

That said, std::unordered_map (and std::map) both overload operator[] which will insert a default if needed:

// if element with a key value one exists, return that. otherwise, insert
// a default initialized element (zero in this case), and return that
auto& val = tempMap[1];