STL map problem! function find()

[jmyrrie]

Good morning, I have a problem when dealing with the map stl library, and It would be great if anyone could help me solve it.

I have this code:

public:
    typedef person* key_person;    
    typedef std::map<  person*, int > friends; //map named " friends" which contains a person and an int. 
private:
    typedef std::map<key_person,friends> graph_data; //map that contains a key_person and another map.
public:
    graph_data data;

Where person is a class.

And then Lets say that I wanna add to "data" a person object name lucy, but without any map friends, I just wanna add lucy to the "data" map , just the person and not another map, remember that data is like this:
map<key_person,friends> where friends is another map.


person* lucy=new person();
data.insert(lucy);

But Im getting an error:
error: no matching function for call to 'std::map<person*, std::map<person*, int> >::insert(person*)'|



I dont wanna add any map friends yet, but i will.
I would really appreciate any given help!

[rmxhaha]

when you insert into a map you need to insert a pair
so insert a pair

data.insert( make_pair( lucy, friends() ) );

friends() is just a blank map
as you said
but why do you need to do that
you can just insert it later on

[Catfish4]

With regards to this part of your code:

person* lucy=new person();
data.insert(lucy);

Be advised that in C++, every new must have a corresponding delete or the program will leak memory.

Perhaps you should rethink your design: is storing pointers to dynamically allocated memory what you really want?

[jmyrrie]

Oh thanks! I got it! I forgot the new
Thanks both of you

Then, if later on I want to insert to lucy a map as the value?
how do i do?

[rmxhaha]

lucy as the value what do you mean ?
the value is an int what value are you talking about

if you want to add value to the map do this

person *bob = new person();
person *lucy = new person();
data[lucy][bob] = 5;

and I agree with CatFish4
it's strange in the way you store pointer as a key value
I mean where would you delete it when you don't need it anymore...

[jmyrrie]

shouldnt I iterate through the map until I find what I wanna delete and make a delete?

I was asked to do a graph of people with maps, where an arc of a vertex represents a friends of the person.

Sorry for not making myself clear, I want this:

friends fr;
fr.insert(make_pair( adam, 1));
fr.insert(make_pair(joel,1));

What I wanna do is add fr to the key lucy, remember you suggested this:

data.insert( make_pair( lucy, friends() ) )
Now I wanna add fr as the value of the key lucy.

Sorry again if I dont make myself clear

[rmxhaha]

no you shouldn't iterate trough it
because map can do binary search which is far better than a linear search
If you want to delete lucy then

data.erase( lucy );

map can delete based on key


if you want to add fr to let's say lucy

auto ptr = data.find( lucy );
if( ptr != data.end() ){
    ptr->second.insert( fr.begin(), fr.end() );
}

if let's say adam has existed inside data[lucy] then it won't be replaced