Mid-Term Exam (1')
C++ Programming
NCNU CSIE

Date: June 23rd, 2010
Time: 16:10-17:00
Open book; turn off computer & mobile phone

1. (20%) 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).
   

   #include <iostream>
   using std::cout;
   
   class CQueue
   {
   public:
           CQueue()        // Default Constructor
           {
                   head = tail = 0;
           }
           void push(int i)
           {
                   a[tail++] = i;
           }
           int pop()
           {
                   return a[head++];
           }
   private:
           #define         QueueSize       10
           int a[QueueSize];
           int head, tail;
   };
   
   int main() {
     CQueue q;
     q.push(3); q.push(2); 
     q.pop();  q.push(6);
     cout << q.pop() << "\n";
   }
   

2. (20%) 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).
   
   #include <iostream>
   using std::cout;
   
   float average(float a, float b);
   float average(float a, float b, float c);       // overloading
   
   int main()
   {
       cout << average(1.0, 5.2, 7.0) << "\n";
       cout << average(4,0, 5.0) << "\n";
       return 0;
   }
   
   float average(float a, float b)
   { return (a+b)/2.0; }
   
   float average(float a, float b, float c)
   { return (a+b+c)/3.0; }
   
   
   
3. (20%) 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).
   
   #include <iostream>
   using std::cout;
   
   void test(int i)
   { cout << ++i << "\n"; }
   
   int main()
   {
       int n = 623;
       test(n);   // pass-by-value or pass-by-reference?
       cout << n << "\n";       
       return 0;
   }
   
   
   
4. (20%) 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).
   

   #include <iostream>
   using std::cout;
   
   int main()
   {
       int i, n = 623;
       for (i=1; i<7; i++)
       {
           int n = 0;
           for (int j=1; j<=i; j++)
               n += j;		// scope of variable n
           cout << n << "\n";
       }
   	cout << n << "\n";
       return 0;
   }

5. (20%) 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).
   
   #include <iostream> // Ex7_06.cpp
   using std::cout;
   using std::endl;
   
   class CBox // Class definition at global scope
   {
   public:
   double m_Length; // Length of a box in inches
   double m_Width; // Width of a box in inches
   double m_Height; // Height of a box in inches
   
   // Constructor definition
   CBox(double lv = 1.0, double bv = 2.0, double hv = 3.0)
   : m_Length(lv), m_Width(bv), m_Height(hv) // Initialization list
       {
       cout << "Constructor called." << endl;
       }
   
   CBox(const CBox& b)
   : m_Length(2*b.m_Length), m_Width(3*b.m_Width), m_Height(b.m_Height) // Initialization list
       {
       cout  << "Copy Constructor called." << endl;
       }
   
   // Function to calculate the volume of a box
   double Volume()
       { return m_Length*m_Width*m_Height; }
   
   };
   
   int main()
   {
   CBox box1; // Declare box1 - no initial values
   CBox box2 = box1; // Default Copy Constructor
   
   cout << "Volume of box2 = " << box2.Volume() << endl;
   return 0;
   }