(C++) How to insert pair into map

Question

I have the following map structure: map < pair < int,int >, object* > and I wish to insert into it. How would I do it since I am trying to insert a pair and an object and I must make a pair out of this. Should I create a new pair using make_pair() out of the pair and object that I have? If so, could you please let me know how to do this?

Thanks

Answer 1

object * myObject = // get an object somehow
myMap.insert(std::make_pair(std::make_pair(1,2), myObject));

or

typedef map<pair<int, int>, object *> MapType;
object * myObject = // get an object somehow
myMap.insert(MapType::value_type(std::make_pair(1,2), myObject));

Answer 2

There are two ways:

typedef std::map<int,Object> map_t;
map_t map;
Object obj;

std::pair<map_t::iterator, bool> result = map.insert(std::make_pair(1,obj)); // 1

map[1] = obj; // 2

1. Only works if the key is not already present, the iterator points to the pair with the key value and the bool indicates if it has been inserted or not.

2. Easier, but if it does not already exist the object is first default constructed and then assigned instead of being copy constructed

If you don't have to worry about performance, just choose by whether or not you wish to erase the previous entry.