STL: set with map usage

[pcej]

Hi,
I have a following problem:
I want to use set that contains map (s).
Here are important parts of my code:

struct position{
	int t[2];
};
//...
//somewhere in main:
map< position, bool> p;
set < map <position, bool> > container;
container.insert(p);

and I'm getting this error:

>main.obj : error LNK2001: unresolved external symbol "bool __cdecl operator<(class std::map<struct position,bool,struct std::less<struct position>,class std::allocator<struct std::pair<struct position const ,bool> > > const &,class std::map<struct position,bool,struct std::less<struct position>,class std::allocator<struct std::pair<struct position const ,bool> > > const &)" (??M@YA_NABV?$map@Upozycja@@_NU?$less@Uposition@@@std@@V?$allocator@U?$pair@$$CBUposition@@_N@std@@@3@@std@@0@Z)

What do I wrong?

[cire]

I want to use set that contains map (s).

Why do you want to do this?

[LB]

std::map wants to know how to sort your positions in order, but it can't figure out how. You need to let it know how:

struct position{
	int t[2];

	bool operator<(const position &other) const
	{
		return t[0] < other.t[0] || t[1] < other.t[1];
	}
};

With this change, your code compiles for me. I would still heed cire's post, though.

[pcej]

@cire:
complexity is very important for me here, and set has quick access with its sorted items;
@L B
I have this operator< and it sorts my positions correctly (edited)

bool operator < ( const position &a, const position &b ){
	if( a.t[0] < b.t[0] )
		return true;
	if( a.t[0] == b.t[0] && a.t[1] < b.t[1] )
		return true;
	return false;
};

[LB]

@pcej so is the problem solved? Your response is not very clear.

[pcej]

not really, it doesnt work and there is no progress

[LB]

Your version of the operator is equivalent to my version.

Are you sure it still does not work? When I compile your code including your version of the operator, it compiles and runs successfully.

[pcej]

int countNext( map<position, bool> p, test t){
	set < map <position, bool> > container;

	container.insert(  p);

	return 0;
};

This is the function that I'm starting to write down. If I comment line 4 it compiles.

Do you have any other ideas?

PS.
I've tried with all stl containers and only vector compiles, but .find() is necessery for me

[LB]

Does pozycja have an overloaded operator<?

[pcej]

Edited

[LB]

My question remains, but for position.

[pcej]

do I need any overloaded operator<? why ? I was told set is able to compare maps(or other stl containers) just like that without operator. ;/

bool operator < ( const map <pozycja, bool> &a, const map <pozycja, bool> &b );

That's the only one operator that I have. Should I write an operator< for set as well ?
edited: solved

[LB]

The error is not related to the set. The error is related to the map not being able to compare your key values. Map keys MUST be comparable via operator<:
http://www.cplusplus.com/reference/map/map/
(see description of "Compare")