國立暨南國際大學 99 學年度第二學期小考試卷

(考試時間: 16:30-16:45)

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).
   
   

   #include <iostream>			
   using std::cout;
   using std::endl;
   
   class CRational 
   {
     public:
       int numerator;		// 分子
   	int denominator;	// 分母
   
   	CRational(int p=0, int q=1)
   		: numerator(p), denominator(q)
   	{
   		if (q==0)
   		{
   			cout << "Error! The denominator cannot be 0.\n";
   			exit(1);
   		}
   	}
   
   	void Print()
   	{
   		cout << numerator;
   		if (denominator != 1)
   			cout << "/" << denominator;
   		cout << endl;
   	}
   
   	CRational operator+(const CRational x) const
   	{
   		return CRational(numerator*x.denominator + denominator*x.numerator,
   			denominator*x.denominator);
   	}
   
   };
      
   int main()
   {
     CRational a, d;
     CRational b(3);
     CRational c(1,7);
     a = b + c + d;	a.Print();
     a = c + c;		a.Print();
     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).
   
   

   #include <iostream>			
   using std::cout;
   using std::endl;
   
   class CRational 
   {
     public:
       int numerator;		// 分子
   	int denominator;	// 分母
   
   	CRational(int p=0, int q=1)
   		: numerator(p), denominator(q)
   	{
   		if (q==0)
   		{
   			cout << "Error! The denominator cannot be 0.\n";
   			exit(1);
   		}
   	}
   
   	void Print()
   	{
   		cout << numerator;
   		if (denominator != 1)
   			cout << "/" << denominator;
   		cout << endl;
   	}
   
   	CRational operator=(const CRational x) 
   	{
   		if (this == &x)
   			return *this;
   		numerator = x.numerator;
   		denominator = x.denominator;
   		return *this;
   	}
   
   };
      
   int main()
   {
     CRational a;
     CRational b(3);
     CRational c(1,7);
     (a = b) = c;	a.Print();  
     return 0;
   }

3. (10%) Consider the function operator+() in Ex8_06.cpp. If the function header
         CBox operator+(const CBox& aBox) const
   is replaced with
         CBox operator+(CBox& aBox)
   will the program compile successfully?