Midterm Exam (3)
C++ Programming
NCNU CSIE

Date: May 18, 2012
Time: 08:30-10:30
Open book; turn off computer & mobile phone

1. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
   // Access Control in a Class
   #include <iostream>
   using std::cout;
   using std::endl;
   
   class CBox
   {
   private:
       int m_Length;
       int m_Width;
       int m_Height;
   protect:
       int Length() { return m_Length; }
       int Width() { return m_Width; }
       int Height() { return m_Height; }
   public:
       CBox(int l, int w, int h):
         m_Length(l), m_Width(w), m_Height(h)
         { }
       void ShowHeight()
       { cout << Height(); }
   };
   
   int main()
   {
       CBox box1(1,2,3);
       box1.ShowHeight();
       return 0;
   }
   
   
   
2. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   

   // Inheritance
   #include <iostream>
   
   class CBox
   {
   public:
           int m_Length;
           int m_Width;
           int m_Height;
   
           CBox(int lv = 1, int wv = 2, int hv = 3)
   	  : m_Length(lv), m_Width(wv), m_Height(hv) {}
           int Volumn() { return m_Length * m_Width * m_Height; }
   };
   
   class CCandyBox: public CBox
   {
   public:
           char m_Contents[10];
           CCandyBox(const char *str = "Candy")
           {
                   strcpy(m_Contents, str);
           }
           CCandyBox(int lv, int wv, int hv, char *str)
   	  : CBox(lv, wv, hv)
           {
                   strcpy(m_Contents, str);
           }
   };
   
   int main()
   {
           CCandyBox myCandyBox(2, 3, 4, "Chocolate");
           CCandyBox myBox;
           std::cout << sizeof(myCandyBox) << std::endl;
           std::cout << myBox.Volumn() << std::endl;
           return 0;
   }
   

   
   
3. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).

   // Size of a binary tree
   #include <iostream>
   
   using std::cout;
   using std::endl;
   
   class CBinaryTree
   {
   public:
   	int value;
   	CBinaryTree* left;
   	CBinaryTree* right;
   	CBinaryTree(int n, CBinaryTree* p1 = NULL, 
   		CBinaryTree* p2 = NULL):
   	  value(n), left(p1), right(p2) {}
   };
   
   int main()
   {
       CBinaryTree G(0);
   	CBinaryTree F(6);
   	CBinaryTree E(9);
   	CBinaryTree D(0);
   	CBinaryTree C(1, &F, &G);
   	CBinaryTree B(9, &D, &E);
   	CBinaryTree A(2, &B, &C);
   
   	cout << sizeof(A) << endl;
       return 0;
   }
   
   

4. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).

   // Recursively output a binary tree
   #include <iostream>
   
   using std::cout;
   using std::endl;
   
   class CBinaryTree
   {
   public:
   	int value;
   	CBinaryTree* left;
   	CBinaryTree* right;
   	CBinaryTree(int n, CBinaryTree* p1 = NULL, 
   		CBinaryTree* p2 = NULL):
   	  value(n), left(p1), right(p2) {}
   
   	void Print()
   	{
   		if (left) left->Print();
   		cout << value;
   		if (right) right->Print();
   	}
   };
   
   int main()
   {
       CBinaryTree G(0);
   	CBinaryTree F(6);
   	CBinaryTree E(9);
   	CBinaryTree D(0);
   	CBinaryTree C(1, &F, &G);
   	CBinaryTree B(9, &D, &E);
   	CBinaryTree A(2, &B, &C);
   
   	C.Print();
       return 0;
   }
   
   

5. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   

   // Friend function
   #include <iostream>
   
   using std::cout;
   using std::endl;
   using std::ostream;
   
   class CBinaryTree
   {
   
   friend ostream& operator<<(ostream& os, CBinaryTree bt)
   {
   		bt.Print();
   		return os;
   }
   
   public:
   	int value;
   	CBinaryTree* left;
   	CBinaryTree* right;
   	CBinaryTree(int n, CBinaryTree* p1 = NULL, 
   		CBinaryTree* p2 = NULL):
   	  value(n), left(p1), right(p2) {}
   
   	void Print()
   	{
   		cout << value;
   		if (left) left->Print();		
   		if (right) right->Print();
   	}
   };
   
   int main()
   {
       CBinaryTree G(0);
   	CBinaryTree F(6);
   	CBinaryTree E(9);
   	CBinaryTree D(0);
   	CBinaryTree C(1, &F, &G);
   	CBinaryTree B(9, &D, &E);
   	CBinaryTree A(2, &B, &C);
   
   	cout << A << endl;;
       return 0;
   }

6. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   

   // Overloading the increment operator
   #include <iostream>
   #include <string>
   
   using std::cout;
   using std::endl;
   using std::string;
   using std::ostream;
   
   class Word
   {
   private:
   	
   public:
   	string word;
   	Word(): word("A") {} ;
   
   	Word& operator++()
   	{		
   		word.insert(0, "B");
   		return *this;
   	}
   
   	const Word operator++(int)
   	{
   		Word w = *this;
   		word.append("C");
   		return w;
   	}
   
   	void Print()
   	{ cout << word << endl; }
   
   	friend ostream& operator<<(ostream& os, Word a)    // P.569
   	{ os << a.word;
   	  return os;
   	}
   
   };
   
   int main()
   {
   	Word a;	
   	++a;	
   	a++; 
   	cout << ++a;
   	cout << a++;
   	cout << endl << a;
   	return 0;
   }
   
   
   
   

7. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   

   // Size of an object with static members
   #include <iostream>
   #include <string>
   
   using std::cout;
   using std::endl;
   using std::string;
   
   class MyView
   {
   public:
   	char type[12];
   	MyView* nextView;
   	static  MyView* firstView;
   	static MyView* lastView;
   
   	MyView(const char* str)
   	{ 
   	    strcpy(type, str);
   	    if (firstView == NULL)		
   			firstView = lastView = this;
   		else
   		{
   			lastView->nextView = this;
   			lastView = this;
   		}
   		nextView = NULL;
   	}
   };
   
   MyView* MyView::firstView = NULL;
   MyView* MyView::lastView = NULL;
   
   int main()
   {
   	MyView view1("Bar Chart");
   	MyView view2("Line Chart");
   	MyView* p;
   	for (p=view1.firstView; p; p = p->nextView)
   		cout << p->type << endl;
   	cout << sizeof(MyView) << endl;
       return 0;
   }

   
   
8. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   

   // Virtual function
   #include <iostream>
   
   using std::cout;
   using std::endl;
   
   class Window // Base class 
   {
   public:
       virtual void Create() // virtual function 
       { cout <<"Base class Window"<< endl; }
   };
   
   class CommandButton : public Window
   {
   public:
       void Create()
       { cout<<"Derived class Command Button"<< endl; }
   };
   
   int main()
   {
       Window  *x, *y;	
     
       x = new Window;
       x->Create();
   
       y = new CommandButton;
       y->Create();	// y is a pointer to the base class type
   	return 0;
   }

9. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   

   // Pointer to the base class
   #include <iostream>
   
   using std::cout;
   using std::endl;
   
   class Window // Base class 
   {
   public:
       void Create() // This is not declared virtual 
       { cout <<"Base class Window"<< endl; }
   };
   
   class CommandButton : public Window
   {
   public:
       void Create()
       { cout<<"Derived class Command Button"<< endl; }
   };
   
   int main()
   {
       Window  *x, *y;	
     
       x = new Window;
       x->Create();
   
       y = new CommandButton;
       y->Create();	// y is a pointer to the base class type
   	return 0;
   }

10. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
    

    // typedef
    #include <iostream>
    #include <vector>
    #include <list>
    
    using std::cout;
    using std::endl;
    using std::vector;
    using std::list;
    
    typedef list<int>::iterator IT;
    
    class CMyList: public list<int>
    {
    public:
        CMyList(IT i1, IT i2)
        {
            for (IT iter = i1; iter != i2; iter++)
                push_back(*iter);
        }
    
        void Print()
        {
            for (IT iter = begin(); iter != end(); iter++)
                cout << *iter << ' ';
            cout << endl;
        }
    };
    
    int main()
    {
        int  phone[] = { 0, 4, 9, 2, 9, 1, 0, 9, 6, 0 };
        vector<int> number(phone, phone+sizeof(phone)/sizeof(phone[0]) );
        list<int> data(number.begin() + 4, number.end());   
        CMyList data2(data.begin() + 2, data.end());
        data2.Print();
        return 0;
    }

11. (10%) Determine whether the following code has syntax erros or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
    

    // Vector Capacity
    #include <iostream>
    #include <vector>
    
    using std::cout;
    using std::endl;
    using std::vector;
    
    int main()
    {
    	vector<int> a;
    	a.reserve(6);
    	for (int i=3; i<18; i++)
    		a.push_back(5);
    	cout << a.size() << '\t'
    		<< a.capacity() << '\n';
    	return 0;
    }