Help with NULL arguments

I'm having trouble with sending NULL as an argument for a pointer. The functions and calls are as follows:

Code:

void room::build_connections(room* uparg, room* downarg, room* northarg, room* southarg, room* eastarg, room* westarg, room* currarg)
{
     to_up=uparg;
     to_down=downarg;
     to_north=northarg;
     to_south=southarg;
     to_east=eastarg;
     to_west=westarg;
     currroom=currarg;
     
     if (to_up != NULL) up_exist=true;
     else up_exist=false;
     if (to_down != NULL) down_exist=true;
     else down_exist=false;
     if (to_north != NULL) north_exist=true;
     else north_exist=false;
     if (to_south != NULL) south_exist=true;
     else south_exist=false;
     if (to_east != NULL) east_exist=true;
     else east_exist=false;
     if (to_west != NULL) west_exist=true;
     else west_exist=false;
}

Code:

room room1("Sup", "Heya", "Wat");
room room2("Desu", "Da ne", "Nyoron~");
    
room1.build_connections(NULL, NULL, room2, NULL, NULL, NULL, room1);
room2.build_connections(NULL, NULL, NULL, room1, NULL, NULL, room2);

What exactly are you having trouble with?

--
Mats

Oh, right, forgot to post the error message I got.

In function `int main()':
no matching function for call to `room::build_connections(NULL, NULL, room&, NULL, NULL, NULL, room&)'
candidates are: void room::build_connections(room*, room*, room*, room*, room*, room*, room*)
no matching function for call to `room::build_connections(NULL, NULL, NULL, room&, NULL, NULL, room&)'
candidates are: void room::build_connections(room*, room*, room*, room*, room*, room*, room*)

Removed for idiocy. Sorry.

NULL is a null pointer literal. It can be any pointer type. As long as you don't have ambiguous overloads, there's no problem.

The problem isn't NULL. The problem is that you're trying to pass the rooms by value when you're supposed to pass a pointer to them, i.e. it should be

Code:

room1.build_connections(NULL, NULL, &room2, NULL, NULL, NULL, &room1);

Thanks! It works now. I probably should have thought of that before.