國立暨南國際大學 105 學年度第二學期小考試卷

1. (10%) Predict the output of the following code.
   
   // Public Data Members (P.437)
   #include <iostream>
   
   class CRect {
   public:
       int left;    int top;
       int right;   int bottom;
   
       CRect(int L, int T, int R, int B) {
           left = L;        top = T;
           right = R;       bottom = B;
       }
   
       int Area() {
           return (right-left) * (bottom-top);
       }
   };
   
   int main()
   {
       CRect a(10, 20, 30, 40);
       std::cout << a.Area() << std::endl;
       CRect* p = &a;
       a.right = 60;
       p->bottom = 70;
       std::cout << p->Area() << std::endl;
       return 0;
   }
   
   
2. (10%) Predict the output of the following code.
   
   // Overloading the Increment Operators (P.348)
   #include <iostream>
   
   class CObj {
       char c;
       int n;
   public:
       CObj(char C, int N): c(C), n(N) {} // Initialization list (P.294)
   
       CObj& operator++() {
           ++c;
           return *this;
       }
   
       CObj operator++(int) {
           CObj obj(*this);
           n++;
           return obj;
       }
   
       void Print() {
           std::cout << c << ' ' << n << std::endl;
       }
   };
   
   int main()
   {
       CObj a('A', 65);    a.Print();
       (++a).Print();
       a++.Print();        a.Print();
       return 0;
   }
   
   
3. (10%) Determine whether the following code is correct or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
   // Inheritance in Classes (P.433)
   #include <iostream>
   
   class CRect {
   public:
       int left;    int top;
       int right;   int bottom;
   
       CRect(int L, int T, int R, int B) {
           left = L;        top = T;
           right = R;       bottom = B;
       }
   };
   
   class MyRect : public CRect {
   public:
       // Constructor Operation in a Derived Class (P.440)
       MyRect(int L, int T, int R, int B): CRect(L, T, R, B) {}
   
       void Move(int dx, int dy) {
           left += dx;       right += dx;
           top += dy;        bottom += dy;
       }
   
       void Print() {
           std::cout << '(' << left << ',' << top << ")-("
                << right << ',' << bottom << ")\n";
       }
   };
   
   int main()
   {
       MyRect bRect(10, 20, 30, 40);
       bRect.Print();
       bRect.Move(10, -5);
       bRect.Print();
       return 0;
   }