Fifos in user space

"...the user space process can have a main() function where it opens a fifo to
communicate with the kernel. To set up communication, I advise only to use fifos

between kernel space and user space, and use the STL queue<Your Type> for
communication between two tasks. For fifos, look at FifoRT[In/Out].hpp and
FifoUS[In/Out].hpp files..."

Can you explain us what do you mean when you say "use the STL queue<Your Type>"?
Is a class?

We have written two simple real-time tasks that communicate through a fifo
(using FifoRT[In/Out]..hpp): we have tried to compile a program in user
space (to communicate with a real-time task) using FifoUS[In/Out].hpp:

#include <FifoUSOut.hpp>

using namespace StoneHead;

int main() {

	WriteInterface* out;
	char* messaggio = "Fifo in User Space";

	out = new FifoUSOut(5);
	out->write(messaggio,strlen(messaggio)+1);

	return 0;
}

The compilation exits because of the error:

"/tmp/cc0TxEnb.o: In function `StoneHead::WriteInterface::~WriteInterface(void)':
/usr/local/orocos/include/WriteInterface.hpp:64: undefined reference to
`inttostring(int)'
collect2: ld returned 1 exit status"

Are we using the class FifoUSOut in a wrong way? Or something else?

Regards

Piercarlo
Fabrizio