We anticipate that many people working on Project 3 will spend a lot of time debugging something that arises from a common novice misunderstanding. To save you that time later, we'll give you a chance to make that mistake in a simpler context, so you can work out that issue and how it manifests itself. (It may turn out that you don't have that misunderstanding, so you won't have any problems during this warmup. Still, keep this warmup in mind, because you may still make the mistake in Project 3.)

You will not turn in any of the code you write because of this warmup. Be sure, though, to run them under g32 to be sure there are no memory leaks.

Material about vectors, lists, and iterators are in lecture9-updated.pptx in the slides for lecture 1 and the STL lectures and slides for lectures 2&3.

1. Implement the removeOdds function:

   	#include <list>
   	#include <vector>
   	#include <algorithm>
   	#include <iostream>
   	#include <cassert>
   	using namespace std;
   
   	  // Remove the odd integers from li.
   	  // It is acceptable if the order of the remaining even integers is not
   	  // the same as in the original list.
   	void removeOdds(list<int>& li)
   	{
   	}
   
   	void test()
   	{
   	    int a[8] = { 2, 8, 5, 6, 7, 3, 4, 1 };
   	    list<int> x(a, a+8);  // construct x from the array
   	    assert(x.size() == 8 && x.front() == 2 && x.back() == 1);
   	    removeOdds(x);
   	    assert(x.size() == 4);
   	    vector<int> v(x.begin(), x.end());  // construct v from x
   	    sort(v.begin(), v.end());
   	    int expect[4] = { 2, 4, 6, 8 };
   	    for (int k = 0; k < 4; k++)
   	        assert(v[k] == expect[k]);
   	}
   
   	int main()
   	{
   	    test();
   	    cout << "Passed" << endl;
   	}
   

2. Implement the removeOdds function:

   	#include <vector>
   	#include <algorithm>
   	#include <iostream>
   	#include <cassert>
   	using namespace std;
   
   	  // Remove the odd integers from v.
   	  // It is acceptable if the order of the remaining even integers is not
   	  // the same as in the original vector.
   	void removeOdds(vector<int>& v)
   	{
   	}
   
   	void test()
   	{
   	    int a[8] = { 2, 8, 5, 6, 7, 3, 4, 1 };
   	    vector<int> x(a, a+8);  // construct x from the array
   	    assert(x.size() == 8 && x.front() == 2 && x.back() == 1);
   	    removeOdds(x);
   	    assert(x.size() == 4);
   	    sort(x.begin(), x.end());
   	    int expect[4] = { 2, 4, 6, 8 };
   	    for (int k = 0; k < 4; k++)
   	        assert(x[k] == expect[k]);
   	}
   
   	int main()
   	{
   	    test();
   	    cout << "Passed" << endl;
   	}
   

3. Implement the removeBad function:

   	#include <list>
   	#include <vector>
   	#include <algorithm>
   	#include <iostream>
   	#include <cassert>
   	using namespace std;
   
   	vector<int> destroyedOnes;
   
   	class Movie
   	{
   	  public:
   	    Movie(int r) : m_rating(r) {}
   	    ~Movie() { destroyedOnes.push_back(m_rating); }
   	    int rating() const { return m_rating; }
   	  private:
   	    int m_rating;
   	};
   
   	  // Remove the movies in li with a rating below 50 and destroy them.
   	  // It is acceptable if the order of the remaining movies is not
   	  // the same as in the original list.
   	void removeBad(list<Movie*>& li)
   	{
   	}
   
   	void test()
   	{
   	    int a[8] = { 85, 80, 30, 70, 20, 15, 90, 10 };
   	    list<Movie*> x;
   	    for (int k = 0; k < 8; k++)
   	        x.push_back(new Movie(a[k]));
   	    assert(x.size() == 8 && x.front()->rating() == 85 && x.back()->rating() == 10);
   	    removeBad(x);
   	    assert(x.size() == 4 && destroyedOnes.size() == 4);
   	    vector<int> v;
   	    for (list<Movie*>::iterator p = x.begin(); p != x.end(); p++)
   	    {
   	        Movie* mp = *p;
   	        v.push_back(mp->rating());
   	    }
   	      // Aside:  In C++11, the above loop could be
   	      //     for (auto p = x.begin(); p != x.end(); p++)
   	      //     {
   	      //         Movie* mp = *p;
   	      //         v.push_back(mp->rating());
   	      //     }
   	      // or    
   	      //     for (auto p = x.begin(); p != x.end(); p++)
   	      //     {
   	      //         auto mp = *p;
   	      //         v.push_back(mp->rating());
   	      //     }
   	      // or    
   	      //     for (Movie* mp : x)
   	      //         v.push_back(mp->rating());
   	      // or    
   	      //     for (auto mp : x)
   	      //         v.push_back(mp->rating());
   	    sort(v.begin(), v.end());
   	    int expect[4] = { 70, 80, 85, 90 };
   	    for (int k = 0; k < 4; k++)
   	        assert(v[k] == expect[k]);
   	    sort(destroyedOnes.begin(), destroyedOnes.end());
   	    int expectGone[4] = { 10, 15, 20, 30 };
   	    for (int k = 0; k < 4; k++)
   	        assert(destroyedOnes[k] == expectGone[k]);
   	    for (list<Movie*>::iterator p = x.begin(); p != x.end(); p++)
   	        delete *p;
   	}
   
   	int main()
   	{
   	    test();
   	    cout << "Passed" << endl;
   	}
   

4. Implement the removeBad function:

   	#include <vector>
   	#include <algorithm>
   	#include <iostream>
   	#include <cassert>
   	using namespace std;
   
   	vector<int> destroyedOnes;
   
   	class Movie
   	{
   	  public:
   	    Movie(int r) : m_rating(r) {}
   	    ~Movie() { destroyedOnes.push_back(m_rating); }
   	    int rating() const { return m_rating; }
   	  private:
   	    int m_rating;
   	};
   
   	  // Remove the movies in v with a rating below 50 and destroy them.
   	  // It is acceptable if the order of the remaining movies is not
   	  // the same as in the original vector.
   	void removeBad(vector<Movie*>& v)
   	{
   	}
   
   	void test()
   	{
   	    int a[8] = { 85, 80, 30, 70, 20, 15, 90, 10 };
   	    vector<Movie*> x;
   	    for (int k = 0; k < 8; k++)
   	        x.push_back(new Movie(a[k]));
   	    assert(x.size() == 8 && x.front()->rating() == 85 && x.back()->rating() == 10);
   	    removeBad(x);
   	    assert(x.size() == 4 && destroyedOnes.size() == 4);
   	    vector<int> v;
   	    for (int k = 0; k < 4; k++)
   	        v.push_back(x[k]->rating());
   	    sort(v.begin(), v.end());
   	    int expect[4] = { 70, 80, 85, 90 };
   	    for (int k = 0; k < 4; k++)
   	        assert(v[k] == expect[k]);
   	    sort(destroyedOnes.begin(), destroyedOnes.end());
   	    int expectGone[4] = { 10, 15, 20, 30 };
   	    for (int k = 0; k < 4; k++)
   	        assert(destroyedOnes[k] == expectGone[k]);
   	    for (vector<Movie*>::iterator p = x.begin(); p != x.end(); p++)
   	        delete *p;
   	}
   
   	int main()
   	{
   	    test();
   	    cout << "Passed" << endl;
   	}
   

5. Make sure you understand why the code below passes the first two tests but fails the third. Draw pictures if necessary. Don't forget the lesson you learn from this problem when working on Project 3.

   #include <iostream>
   #include <vector>
   #include <list>
   using namespace std;
   
   const int MAGIC = 11223344;
   
   void test()
   {
       bool allValid = true;
   
       vector<int> v1(5, MAGIC);
       int k = 0;
       for ( ; k != v1.size(); k++)
       {
           if (v1[k] != MAGIC)
           {
               cout << "v1[" << k << "] is " << v1[k] << ", not " << MAGIC <<"!" << endl;
               allValid = false;
           }
           if (k == 2)
           {
               for (int i = 0; i < 5; i++)
                   v1.push_back(MAGIC);
           }
       }
       if (allValid  &&  k == 10)
           cout << "Passed test 1" << endl;
       else
           cout << "Failed test 1" << endl;
   
       allValid = true;
       list<int> l1(5, MAGIC);
       k = 0;
       for (list<int>::iterator p = l1.begin(); p != l1.end(); p++, k++)
       {
           if (*p != MAGIC)
           {
               cout << "Item# " << k << " is " << *p << ", not " << MAGIC <<"!" << endl;
               allValid = false;
           }
           if (k == 2)
           {
               for (int i = 0; i < 5; i++)
                   l1.push_back(MAGIC);
           }
       }
       if (allValid  &&  k == 10)
           cout << "Passed test 2" << endl;
       else
           cout << "Failed test 2" << endl;
   
       allValid = true;
       vector<int> v2(5, MAGIC);
       k = 0;
       for (vector<int>::iterator p = v2.begin(); p != v2.end(); p++, k++)
       {
           if (k >= 20)  // prevent infinite loop
               break;
           if (*p != MAGIC)
           {
               cout << "Item# " << k << " is " << *p << ", not " << MAGIC <<"!" << endl;
               allValid = false;
           }
           if (k == 2)
           {
               for (int i = 0; i < 5; i++)
                   v2.push_back(MAGIC);
           }
       }
       if (allValid  &&  k == 10)
           cout << "Passed test 3" << endl;
       else
           cout << "Failed test 3" << endl;
   }
   
   int main()
   {
       test();
   }