國立暨南國際大學 102 學年度第二學期 第二次期中考試卷

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).
   
   // Conditional Operator (P.133)
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main()
   {
       int a = 1;
       cout << (--a ? a : a=2);
       cout << --a << endl;
       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).
   
   // Operator Precedence (P.77)
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main()
   {
       int a = 5;
       cout << (a-=2 ? a : a=2);
       cout << --a << 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).
   
   // Bitwise Operators (P.82)
   // std::hex (P.148)
   #include <iostream>
   #include <iomanip>
   using std::cout;
   using std::endl;
   using std::hex;
   
   int main()
   {
       int a = (((16 << 8) | 20 ) << 8 | 30 ) << 8 | 40;
       cout << hex << 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).
   
   // strlen vs. sizeof (P.190)
   #include <iostream>
   #include <cstring>
   using std::cout;
   using std::endl;
   
   int main()
   {
       char str[] = "National Chi Nan University";
       str[8] = '\0';
       cout << sizeof(str) << '\t'
           << strlen(str) << endl;
       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).
   
   // Type Conversion (P.78)
   // switch (P.135)
   #include <iostream>
   using std::cout;
   
   int main()
   {
       int even = 0, odd = 0;
       char str[] = "Singapore"; // 'A' == 65, 'a' == 97
       for (int i=0; i<strlen(str); i++)
           switch ( str[i] % 2 )
           {
               case 0:
                   even++;
                   break;
               case 1:
                   odd++;
                   break;
           }
       cout << "odd = " << odd << '\n'
            << "even = " << even << '\n';
       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).
   
   // Pointers and Arrays (P.194)
   #include <iostream>
   using std::cout;
   
   int main()
   {
       int data[] = { 1, 2, 3, 4, 5};
       int* pdata = data;
       cout << *pdata;
       pdata += 4;
       cout << *pdata;
       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).
   
   // Recursive Function Calls (P.285)
   #include <iostream>
   using std::cout;
   
   void octal(int n)
   {
       if (n >= 8 )
          octal(n / 8);
       cout << n;
   }
   
   int main()
   {
       octal(20);
       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).
   
   // Pass-by-Reference (P.267)
   #include <iostream>
   
   void swap(int &i, int j)
   {
       int temp;
       temp = i;
       i = j;
       j = temp;
       return;
   }
   
   int main()
   {
       int a = 4;
       int b = 19;
       std::cout << a << b << std::endl;
       swap(&a, b);
       std::cout << a << b << 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).

   // Function Overloading (P.310)
   #include <iostream>
   using std::cout;
   
   void star(int n, int c)
   {
       for (int i=0; i<n; i++)
           cout << static_cast<char>(c);
   }
   
   void star(int n, char c)
   {
       for (int i=0; i<n; i++)
           cout << c;
   }
   
   int main()
   {
       star(3, 50);
       star(5, 'A');
       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).

    // Arrays of Pointers to Functions (P.301)
    #include <iostream>
    using std::cout;
    
    int f0(int n)
    {
        return 1;
    }
    
    int f1(int x)
    {
        return x;
    }
    
    int f2(int x)
    {
        return x*x;
    }
    
    int f3(int x)
    {
        return x*x*x;
    }
    
    int main()
    {
        int a[] = { 1, 2, 3, 4, 5 };
        int (*pfunc[4]) (int) = { f0, f1, f2, f3 };
        int (*pf) (int) = *(pfunc + 2);
        int sum = 0;
        for (int i=0; i< sizeof(a)/sizeof(a[0]); i++)
            sum += pf(a[i]);
        std::cout << sum << std::endl;
        return 0;
    }