國立暨南國際大學 103 學年度第二學期 第一次期中考試卷

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).
   // Decrement Operator (P.59)
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main()
   {
       int a = 29;
       int b = 3;
       cout << a-- - --b << endl;
       cout << a << b << endl;
       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).
   
   // Shorthand notation (P.58)
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main()
   {
       int a = 2020;
       int b =    4;
       int c =    1;
       a /= b + c;
       cout << a << endl;
       return 0;
   }
   
   
3. (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).
   
   // Type Conversion (P.63)
   #include <iostream>
   using std::cout;
   using std::endl;
   
   int main()
   {
       float R = 2.0;
       float A = 3 / 4;
       cout << A * R * R << endl;
       cout << R * R * A << endl;
       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).
   
   // Conditional Operator (P.103)
   #include <iostream>
   
   int main()
   {
       int i;
       for (i=5; i<=9; i++)
           std::cout << ( i % 2 ? "Even" : "Odd" ) << std::endl;
       return 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).
   
   // for Loop (P.110)
   #include <iostream>
   
   int main()
   {
       int i;
       int sum = 41;
       for (i=5; i<=9; i+=2)  
           std::cout << i << std::endl;
           sum += i;
       std::cout << sum << std::endl;
       return 0;
   }
   
   
6. (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).
   
   // MATH Functions
   #include <iostream>
   #include <cmath>
   using std::cout;
   using std::endl;
   
   int main()
   {
       float b = -4.1;
       int n = b;
       int m = abs(b);
       float a = fabs(b);
       cout << n << endl;
       cout << m << endl;
       cout << a << endl;
       cout << ceil(b) << endl;
       cout << floor(b) << endl;
       return 0;
   }
   
   
7. (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).
   

   // Substitution Cipher
   #include <iostream>
   
   int main()
   {
       char ciphertext[] = "NKGGYWKKI";
       char password[]   = "CALIFORNIA";
       char alphabet[]   = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
       char mapping[26];
       char reverse[26];
       char c;
       unsigned short i, j, k;    
       // Preparing the mapping table
       for (k=0, i=0; (c=password[i]) != '\0'; i++)    
       {
           if (alphabet[ c - 'A' ] != 0)
           {
               mapping[k++] = c;
               alphabet[ c - 'A' ] = 0;
           }
       }
       for (j=0; k<26; )
       {
           while (alphabet[j] == 0) j++;
           mapping[k++] = alphabet[j++];
       }
       // mapping[k] = '\0';
       // std::cout << "DEBUG - " << mapping << std::endl;
   
       for (i=0; i<26; i++)
           reverse[ mapping[i] - 'A' ] = 'A' + i;
   
       for (i=0; (c=ciphertext[i]) != '\0'; i++)
           std::cout << reverse[ c - 'A' ];
       std::cout << std::endl;
   
       return 0;
   }

   
   
   
8. (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).
   
   // Type Conversion (P.63)
   // switch (P.105)
   #include <iostream>
   using std::cout;
   
   int main()
   {
       int even = 0, odd = 1;
       char str[] = "CALIFORNIA"; // 'A' == 65
       for (int i=0; i<10; i++)
           switch ( str[i] % 2 )
           {
               case 0:
                   even++;
                   break;
               case 1:
                   odd++;
                   break;
           }
       cout << "odd = " << odd << '\n'
            << "even = " << even << '\n';
       return 0;
   }
   
   

9. (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).
   
   // Initialize an Array (P.134)
   #include <iostream>
   using std::cout;
    
   int main()
   {
       const int N = 5;
       int data[N] = { 3 * N };
       int i;
       for (i=1; i<N; i+=2)           
           data[i] = i;       
       for (i=0; i<N; i++)
           cout << data[i] << std::endl;       
       return 0;
   }
   
   
   

10. (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).

    // continue (P.116) vs. break (P.115)
    #include <iostream>
    
    int main()
    {
        const int K = 5;
        int count = 0;
        int i, j;
        for (i=0; i<K; i++)
            for (j=0; j<K; j++)
            {            
                if (i == j) break;
                ++count;
            }
        std::cout << count << std::endl;
        return 0;
    }
    
    

11. (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).

    // continue (P.116) vs. break (P.115)
    #include <iostream>
    
    int main()
    {
        const int K = 5;
        int count = 0;
        int i, j;
        for (i=0; i<K; i++)
            for (j=0; j<K; j++)
            {
                if (i == j) continue;
                ++count;
            }
        std::cout << count << std::endl;
        return 0;
    }

12. (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).

    // Transposition Cipher - Scytale
    // The input key specifies the diameter of the scytale
    #include <iostream>
    #include <cstring>
    #include <cmath>
    using std::cin;
    using std::cout;
    using std::endl;
    
    int main()
    {
        const int key = 6;
        const int height = key;
        const int MAX_MESSAGE_LENGTH = 200;
        char plaintext[ MAX_MESSAGE_LENGTH];
    
        char ciphertext[ MAX_MESSAGE_LENGTH ] =
            "SFAKI IOTUEANUHASGGNEN EADR A PI YTOONLE FRGEWT E E H9 F DE1";
        unsigned i, j, width;
    
        int length = 0;
        while (ciphertext[length] != '\0')
            length++;
        width = ceil(1.0 * length / height);
    
        for (j=0; j<width; j++)
        for (i=0; i<height; i++)
            {
                plaintext[i * width + j] = ciphertext[i + height * j] ;
            }
        plaintext[ width * height ] = '\0';
        cout << plaintext << endl;
        return 0;
    }