國立暨南國際大學 103 學年度第二學期小考試卷

1. (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).
   
   // sizeof()
   #include <iostream>
   
   int main()
   {
       char msg[20] = "CAESAR CIPHER";
       std::cout << sizeof(msg) << '\n';
       std::cout << static_cast<unsigned short>(msg[0]) << '\n';
       std::cout << sizeof(msg[0]) << '\n';
       return 0;
   }
   
   
   
2. (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).
   
   // Caesar Cipher
   #include <iostream>
   
   int main()
   {
       char msg[20] = "CAESAR CIPHER";
       char new_msg[20] = { 0 };
       int key = 3;
       int i, len;
       for (i=0; i<20; i++)
       {
           new_msg[i] = msg[i] + key;
           if (msg[i] == '\0') break;
       }
       for (len=0; len<20; len++)
           if (new_msg[len] == '\0') break;
       std::cout << len << std::endl;
       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).
   
   // Matrix
   #include <iostream>
   #include <iomanip>
   
   int main()
   {
       int a[3][3] = { {2,4,6}, {3,5,7}, {1,6,8} };
       int b[3][3] = { {1,4,7}, {2,5,8}, {3,6,9} };
       int c[3][3] = { 0 };
       int i, j, k;
   
       for (i=0; i<3; i++)
           for (j=0; j<3; j++)
               for (k=0; k<3; k++)
                   c[i][j] += a[i][k] * b[j][k];
   
       for (i=0; i<3; i++)
       {
           for (j=0; j<3; j++)
               std::cout << std::setw(4) << c[i][j];
           std::cout << std::endl;
       }
   
       return 0;
   }