國立暨南國際大學 100 學年度第一學期小考試卷                   (考試時間: 8:50-9:30)

科目名稱：資訊系統 與網路導論		開課系所：資訊工程 學系		任課教師	吳坤熹
系所別：	年級：	學號：	姓名：	考試日期	2012.1.6

1. (10%) Determine whether the following code has syntax errors 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 = 0102;       // Is "0102" different from "102"?
       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;
   }
   
   
2. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   // modulus
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int mod(int a, int b)
   {
         do a -= b;
         while (a >= b);
         return a;
   }
   
   int main()
   {
         cout << mod(0106, 7) << endl;
         return 0;
   }
   
   
   
3. (10%) Consider the following code to decrypt the Caesar Cipher.  If you want to corrently obtain the answer "HELLO NCNU", what statement should be in the blank (1)?
   
1. *a = (*a - 'A' + key) % 26 + 'A';
2. *a = (*a - 'A' - key) % 26 + 'A';
3. *a = (*a - 'A' + key) % 26 - 'A';
4. *a = (*a - 'A' - key) % 26 - 'A';
   
   // Caesar Cipher
   #include <iostream>
   using std::cout;
   using std::endl;
   
   void decrypt(char* a, int key)
   {
      while (*a)
      {
         if (*a >= 'A' && *a <='Z')
                   (1)       
         a++;
      }
   }
   
   int main()
   {
      char msg[] = "KHOOR QFQX";
      decrypt(msg, 3);
      cout << msg << "\n";
          return 0;
   }
   
   
4. (10%) Determine whether the following code has syntax errors 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(1.2, 5.2, 7.2) << "\n";
       cout << average(3.0, 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; }
   
   
5. (10%) Determine whether the following code has syntax errors or not.  If it is correct, predict its output.  If it is incorrect, point out the mistake(s).
   
 // binary tree
#include <iostream>
using std::cout;

struct Node
{
    char label;
    Node* left;
    Node* right;
};

void postorder(Node* p);    

int main()
{
   
    Node Second       = { 'B', NULL, NULL };
    Node Third        = { 'C', NULL, NULL };

    Node Fifth        = { 'E', NULL, &Second };
    Node Sixth        = { 'F', &Third,  };
    Node Seventh      = { 'G', &Fifth, &Sixth };

    postorder(&Seventh);
    return 0;
}

void postorder(Node* p)
{
    if (p)
    {
        cout << p->label;
        postorder(p->left);
        postorder(p->right);
    }
}