Exercise 14:

Create a directory ex14 and store in this directory the files corresponding to your solutions to the following questions.

Question 1: Vector, iterator and copy (30 points).

Create a vector of char which stores the letters of the alphabet in order. Print the elements of the vector in order and in reverse order using std::copy and a stream iterator. Save the result in a file named "vector_q1.cpp".

Question 2: implementation of an inventory (40 points).

Get the files inventory.h and inventory.cpp. In file "inventory.h", two classes are defined: Item and Inventory. An item is simply identified by its id. An inventory contains a list of items which are in stock (in_stock)) and a list of ids corresponding to items that have already been ordered (ordered). There are two methods used to manipulate an inventory: order() and shipped():

order(int id): is called when a customer wants to order an item by its id. order() should first check if the item is in stock. If yes: then the item should be removed from the stock. Otherwise: the id corresponding to the requested item should be put in the list of back ordered items.
shipped(int id): is called when an item identified by id has been received. We need to check if the corresponding item has been ordered by a client. If it is the case we should remove it from list of ordered items. Otherwise we can simply add it to our stock.

You need to complete the code in the file "inventory.cpp".

Output for the example code in main() should be:

Order for 1 received.
Not in stock. Ordering item with id 1
Order for 2 received.
Not in stock. Ordering item with id 2
Received shipment of item with id 1
1 was ordered by customer. Ship it.
Received shipment of item with id 2
2 was ordered by customer. Ship it.

Question 3: Function objects and algorithms from the standard library (30 points).

This question will help you to check your understanding of function objects and algorithms from the standard library.

Your goal for this exercise will be to write a function object that will be used to sort two dimensional points in a vector of points according to their distance to the origin.
The distance to the origin for a point p of coordinates (x,y) is given by Sqrt(x^2 + y^2). The method norm() in the class Point_2d is computing that distance for you.

To complete this task, please create a file "test_function_algorithms.cpp" and type and complete the following code:

// test_function_algorithms.cpp
#include <algorithm>
#include <vector>
#include <cmath>
#include <ostream>

class Point_2d {
public:
 Point_2d(double x, double y) : x_(x), y_(y) {}
 double norm() const { return sqrt(x_*x_ + y_*y_); }
 double x() const { return x_; }
 double y() const { return y_; }

private:
 double x_, y_;
};

std::ostream& operator<< (std::ostream& os, const Point_2d& p) 
{
  os << "(" << p.x() << ", " << p.y() << ")" << std::endl;
  return os;
}

// Function object to compare Point_2d according to their distance 
// to the origin.
// Example of use:
//  Less_Point_2d less;
//  Point_2d p1(1.0, 2.0), p2(2.0, 2.0);
//  bool t = less(p1, p2); // t == true;
class Less_Point_2d {
// complete the code to turn this class into a function object
// according to the example above
};


int main()
{
  Point_2d p1(0.0, 0.0), p2(1.0, 2.0);
  Point_2d p3(2.0, 2.0), p4(1.5, 1.5);
  Point_2d p5(0.5, 1.5);

  std::vector<Point_2d> v;
  v.push_back(p1); v.push_back(p2);
  v.push_back(p3); v.push_back(p4);
  v.push_back(p5);

  Less_Point_2d less;

  sort(/* complete the argument of sort() such that v is sorted by dist to origin */);

  std::vector<Point_2d>::iterator it;
  for (it = v.begin(); it != v.end(); it++)
  {
    std::cout << *it << std::endl;
  }
}