Mid-term Exam (2)
Introduction to Computer Science
NCNU CSIE

Date:  March 26, 2013
Time: 14:10-16:00
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).
   
   // Class definition
   #include <iostream>
   #include <cstring>
   
   class CMessage
   {
   public:
       CMessage(char* s)
       {
           str = new char[strlen(s) + 1];
           strcpy(str, s);
       }
   
       ~CMessage()
       {
           delete str;
           str = NULL;
       }
   
   private:
           char* str;   
   }
   
   int main()
   {
       CMessage city("Vatican");   
       std::cout << sizeof(city) << std::endl;   
       return 0;
   }
   
   
   
   
2. (10%) What will be the output of the following program?
   
   // Copy Constructor
   #include <iostream>
   
   class CBox                          // Class definition at global scope
   {
   public:
       int m_Length;                   // Length of a box in inches
       int m_Width;                    // Width of a box in inches
       int m_Height;                   // Height of a box in inches
   
       CBox(int lv = 0, int wv = 0, int hv = 0)    // Constructor
           : m_Length(lv), m_Width(wv), m_Height(hv)
       { }
   
       CBox(const CBox& aBox)            // Copy Constructor
       {
           m_Length = aBox.m_Length;
           m_Width  = aBox.m_Width;
           m_Height = aBox.m_Height * 2;
       }
   
       int Volume()
       {
           return m_Length * m_Width * m_Height;
       }
   };
   
   int main()
   {
     CBox box1(3, 4, 5);               // Declare box1 of type CBox
     CBox box2 = box1;                 // Declare box2 of type CBox
     CBox box3;                        // Declare box3 of type CBox
     box3 = box1;
     std::cout << box2.Volume() << std::endl;
     std::cout << box3.Volume() << std::endl;
     return 0;
   }

3. (10%) What will be the output of the following program?
   
   // Default values for constructor arguments
   #include <iostream>
   using std::cout;
   using std::endl;
   
   class CRational
   {
   private:
       int denominator;
       int numerator;
   public:
       void Print()
       {
           cout << numerator << "/" << denominator << endl;
       }
       CRational()    // Default Constructor
       {
           numerator = 0;
           denominator = 1;
       }
       CRational(int a, int b = 1)
       {
           numerator=a;
           denominator=b;
       }
   };
   
   int main()
   {
       CRational p(3, 4);
       CRational q;
       CRational r(5);
       p.Print(); q.Print(); r.Print();
       return 0;
   }
   
   
   
   
   
   
   
   
4. (10%) What will be the output of the following program?
   
   // Overloading the Assignment Operator
   #include <iostream>
   using std::endl;
   using std::cout;
   
   class CData
   {
       public:
           int* pdata;
   
       CData(int n=0)
       {
           pdata = new(int);
           *pdata = n;       
       }
   
       ~CData()
       { delete pdata; }
   
       CData& operator=(const CData& d)
       {
           if (this == &d)
              return *this;
           delete pdata;
           pdata = new int;
           *pdata = ( *(d.pdata) ) --;
           return *this;
       }
   };
   
   
   int main()
   {
       CData a(3);
       CData b(2);
       CData c(9);
       a = b = c;
       cout << *(a.pdata) << *(b.pdata) << *(c.pdata) << endl;
       return 0;
   }
   
   
   
   
5. (10%) What will be the output of the following program?
   
   // Overloading the Assignment Operator
   #include <iostream>
   using std::endl;
   using std::cout;
   
   class CData
   {
       public:
           int* pdata;
   
       CData(int n=0)
       {
           pdata = new(int);
           *pdata = n;       
       }
   
       ~CData()
       {
           cout << "Destructor called to release the memory storing "
                   << *pdata << endl;
           delete pdata;
       }
   
       CData& operator=(const CData& d)
       {
           if (this == &d)
              return *this;
           delete pdata;
           pdata = new int;
           *pdata = ( *(d.pdata) ) --;
           return *this;
       }
   };
   
   
   int main()
   {
       CData a(3);
       CData b(2);
       CData c(9);
       (a = b) = c;
       cout << *(a.pdata) << endl;
       return 0;
   }
   
   
   
6. (10%) What will be the output of the following program?
   
   // Overloading the Assignment Operator
   #include <iostream>
   using std::endl;
   using std::cout;
   
   class CData
   {
       public:
           int* pdata;
   
       CData(int n=0)
       {
           pdata = new(int);
           *pdata = n;      
       }
   
       ~CData()
       {
           cout << "Destructor called to release the memory storing "
                   << *pdata << endl;
           delete pdata;
       }
   
       CData& operator=(const CData& d)
       {
           if (this == &d)
              return *this;
           delete pdata;
           pdata = new int;
           *pdata =  ++*(d.pdata);
           return *this;
       }
   };
   
   
   int main()
   {
       CData a(3);
       CData b(2);
       CData c(9);
       a = b = c;
       cout << *(a.pdata) << endl;
       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).
   
   // Static data members
   #include <iostream>
   
   class CData
   {
   public:
       int value;
       static int nCapacity;
       CData(int n): value(n) { --nCapacity; }
   };
   
   CData::nCapacity = 5;
   
   int main()
   {
       CData a(5);
       CData b(4);
       std::cout << a.nCapacity << std::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).
   
   // Size of a string
   #include <iostream>
   #include <cstring>
   
   class CMessage
   {
   public:
       char str[20];    
       CMessage(char* s)
       { strcpy(str, s); }
   };
   
   int main()
   {
       CMessage city("Vatican");    
       std::cout << sizeof(city) << std::endl;
       std::cout << strlen(city.str) << std::endl;
       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).

   // Size of an object
   #include <iostream>
   #include <cstring>
   
   class CMessage
   {
   public:
   	char* str;	
   	CMessage(char* s)
   	{ 
   		str = new char[strlen(s) + 1];
   		strcpy(str, s); 
   	}
   
   	~CMessage()
   	{
   		delete str;
   		str = NULL;
   	}
   };
   
   int main()
   {
   	CMessage city("Vatican");	
   	std::cout << sizeof(city) << std::endl;
   	// Assume that you are running this program on a 32-bit operating system
   	std::cout << strlen(city.str) << std::endl;
   	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).

    // Access Control
    #include <iostream>
    
    class CBox                          // Class definition at global scope
    {
    private:
        int m_Length;                   // Length of a box in inches
        int m_Width;                    // Width of a box in inches
        int m_Height;                   // Height of a box in inches
    
        CBox(int lv, int wv, int hv)    // Constructor
        {
            m_Length = lv;
            m_Width  = wv;
            m_Height = hv;
        }
    
    public:
        int Volume()
        {
            return m_Length * m_Width * m_Height;
        }
    };
    
    int main()
    {
      CBox box1(2, 3, 4);                // Declare box1 of type CBox
      std::cout << box1.Volume() << std::endl;
      return 0;
    }
    
    
    

11. (10%) Consider the (unmodified) code of Ex8_14.cpp.  If you provide "is is is *" as the input, what would be the output?