Question

I can’t quite seem to figure out why this doesn’t work. I tried to make a queue of pointer types and it failed. I have a class Room, and I want to make a queue of pointers to Room.. so I did:

queue<*Room> bfsRooms;

this gave me the error:

`*’ cannot appear in a constant-expression

Does this mean it is impossible to make a STL queue of pointers?

Answer 1

No it should be fine, you should really link the exact code and exact error so we can help you better.

That said a queue of pointers would look something like this:

 Room r;
 std::queue<Room*> rooms;
 rooms.push(&r);

EDIT: it is worth noting that if these pointer own their objects they point to you should really encapsulate the pointer in a smart pointer, something like:

std::queue<std::unique_ptr<Room>> rooms;

This abide by the RAII principle and will automatically clean up resources.