proper use of c++ standard queue - c++

Question

I am using Visual Studio 2013.
I am using the following as part of my code:
#include <queue>
#include <curses> // pdcurses for mvprintw function
using namespace std;
typedef unsigned short ushort;
struct xy{
int x;
int y;
};
void move(ushort length, queue<xy>& test);
int main() {
// ...
}
void move(ushort length, queue<xy>& test) {
queue<xy> coord;
if (length <= test.size()) {
coord = test.pop();
mvprintw(coord.y, coord.x, " ");
}
// ...
}
If I were to use the queue I made (which does not allow for templates), setting it up to use that struct as its type, it works fine. However, I want to make use of a templated queue so I can use queues of other types as well. But when I use the c++ standard queue in the way given above, I get the following error:
error C2679: binary '=' : no operator found which takes a right-hand operand of type 'void' (or there is no acceptable conversion)
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\queue(101): could be 'std::queue<xy,std::deque<_Ty,std::allocator<_Ty>>> &std::queue<_Ty,std::deque<_Ty,std::allocator<_Ty>>>::operator =(std::queue<_Ty,std::deque<_Ty,std::allocator<_Ty>>> &&)'
1> with
1> [
1> _Ty=xy
1> ]
1> c:\program files (x86)\microsoft visual studio 12.0\vc\include\queue(43): or 'std::queue<xy,std::deque<_Ty,std::allocator<_Ty>>> &std::queue<_Ty,std::deque<_Ty,std::allocator<_Ty>>>::operator =(const std::queue<_Ty,std::deque<_Ty,std::allocator<_Ty>>> &)'
1> with
1> [
1> _Ty=xy
1> ]
1> while trying to match the argument list '(std::queue<xy,std::deque<_Ty,std::allocator<_Ty>>>, void)'
1> with
1> [
1> _Ty=xy
1> ]
Am I missing something simple? I don't see why it seems to think the pop function returns a void type. Does the queue not use pop() for what I think it does? Or is the error in how I am using the Queue in my code?

Answer 1

It looks like you meant to declare coord to be of type xy, not queue<xy>.
Popping from std::queue indeed returns nothing; it simply removes the front element. If you want the front element, call front and then pop.
coord = test.front();
test.pop();