******** fig3.60 **********

	unsigned int
	succ( unsigned int value, QUEUE Q )
	{
		if( ++value == Q->q_max_size )
			value = 0;
		return value;
	}

	void
	enqueue( element_type x, QUEUE Q )
	{
		if( is_full( Q ) )
			error("Full queue");
		else
		{
			Q->q_size++;
			Q->q_rear = succ( Q->q_rear, Q );
			Q->q_array[ Q->q_rear ] = x;
		}
	}