Instructions

1. Write your name clearly at the top of the exam.
2. This paper exam has 8 problems worth 100 points.
3. The coding portion of the exam is worth 50 points.
4. The total exam is 150 points and you will be graded out of 150 points. For example 125/150 will be scored as 83%.
5. Ensure that you write clearly and legibly. Failure to do so may result in the deduction of points.
6. No electronic devices are allowed and all electronic devices that you have with you must be turned off, including calculators.
7. You may not use any notes for this exam.
8. Good luck!

1. (10 points) Suppose I want to declare a class named Picture and use it in a program named Photoshop.cpp. Answer the following questions:
   1. In what file should the class declaration for Picture be placed? Give the name of the file, following the naming conventions discussed in class.

   2. How would you include in a .cpp file the file containing Picture's class declaration?

   3. Using a single g++ statement, how could I compile all of these files into an executable named Photoshop?

   4. Suppose instead that I wanted to separately compile these files and then link together their object files into an executable named Photoshop. Write the set of statements that would be required to perform this separate compilation and then linking into the executable.

   5. Suppose I want to execute Photoshop from the command line by 1) redirecting stdin from a file named bvz.pgm, and 2) redirecting stdout to a file named edited_bvz.pgm. Write the command that I should use to execute Photoshop.

2. (6 points) The following program is supposed to print the sum of two numbers.

   #include <iostream>
   using namespace std;
   
   int main(int argc, char **argv) {
      int num1, num2;
   
      cin >> num1 >> num2;
      cout << num1 + num2 << endl;
      return 0;
   }
       

   When the user tries to execute the program with the command:

   ./sum 3 6
   	

   nothing happens--nothing gets printed and you do not get returned to the unix prompt. It appears as though the program is in an infinite loop, but it is not. Why is the program unresponsive and what must you do to get the program to print something and terminate? Your answer must be no longer than 4 sentences.

3. (16 points) Declare a class named Checkerboard that you could place in a .hpp file. Do not write the method definitions as these would not go in a separate .cpp file. Checkerboard should have the following variables and methods:
   • board: a 2D vector of char's
   • playerTurn: A boolean variable indicating which player's turn it is.
   • A void, 0-argument method named initializeCheckerboard that initializes the board and playerTurn.
   • A void, 1-argument method named initializeCheckerboard that takes a Checkerboard object as a parameter and uses it to initialize the board and the player's turn. This method does not modify its argument.
   • printBoard: a void method that takes 0 arguments and prints the board. printBoard does not modify any of the Checkerboard's member variables.
   • move: a boolean method that takes a string indicating a player's move and updates the checkerboard with the move. move returns true if the move is valid and false if the move is invalid. move does not modify the string parameter.
   • winner: a 0 argument method that takes no arguments and checks to see if there is a winner. It returns an int denoting the winner or -1 if there is no winner as of yet. winner does not modify any of the Checkerboard's member variables.

4. (12 points) The following code fragment is trying to shift all elements in a vector 3 entries to the right and replace the vacated entries with 0:

       vector<int> v;
       int i;
       int originalSize;
   
       // (1) resize the vector
       originalSize = v.size();
       v.resize(v.size() + 3);
   
       // (2) shift the existing entries to the right
       for (i = 0; i < originalSize; i++) {
           v[i+3] = v[i];
       }
   
       // (3) fill the vacated entries with 0's
       for (i = 0; i < 3; i++) {		    
           v[i] = 0;
       }		    
   

   Suppose that v contains the contents:

   0	1	2	3	4	5	6	7
   10	20	30	40	50	60	70	80

   The code fragment is intended to produce the following result:

   0	1	2	3	4	5	6	7	8	9	10
   0	0	0	10	20	30	40	50	60	70	80

   The code fragment as written does not achieve its intended purpose. Answer the following questions:

   1. Show what the contents of the vector actually look like after the above code fragment executes. I have provided too many vector entries. Leave the undefined entries empty.

      0	1	2	3	4	5	6	7	8	9	10	11	12

   2. What is the code fragment doing wrong? You must limit your answer to 3 sentences or less.
   3. Rewrite one or more of the numbered code blocks so that the code fragment correctly shifts the existing vector elements and assigns 0's to the vacated entries. Clearly indicate which numbered code block(s) you are altering.
5. (24 points)
   1. Insert the keys 32, 12, 48, 19, 52, 58, 30, 25 into the following two hash tables using a) linear probing, and b) quadratic probing. You should use the hash function:

      h(key) = key % 11
      

      	Linear Probing	Quadratic Probing
      0
      1
      2
      3
      4
      5
      6
      7
      8
      9
      10

   2. For both linear and quadratic probing please complete the following two tables showing the comma, separated list of entries you would probe in order to insert each key (e.g., if linear probing examined entries 2, 3, and 7 in order to insert 32, then you would write (2, 3, 7) next to 32 in the linear probing table--this is only an example--it is not the actual set of entries you will probe for 32). This will allow us to assign you partial credit if you do not get the entries correct in the linear and quadratic probing hash tables.

      key linear probing 32   12   48   19   52   58   30   25

      key quadratic probing 32   12   48   19   52   58   30   25

6. (12 points) Please read the following instructions before attempting this problem:
   • For part (a) convert the hexadecimal number to binary (0's and 1's).
   • For parts (b)-(d) give the hexadecimal result of the operation. Assume that there is only 8 bits in which to store the result (this is only relevant for part d). For these three parts, if you cannot figure out the hexadecimal representation of the answer you can get 2 points for each part by giving the binary representation of the answer.
   • You can show your work in the blank spaces to get partial credit:

   1. 0x6D = ____________________________

   2. (1001 0101) ^ (1010 1100) = _____________________________

   3. (1001 0101) | (1010 1100) = _____________________________

   4. (1010 1100) >> 3 = _______________________________

7. (8 points) Suppose I have the following declarations and code:

        int a, b;
        int *x, *y;
   

   Also suppose that the above variables are assigned the following memory addresses:

        a: 0x1000
        b: 0x1004
        x: 0x1008
        y: 0x100c
    

   After the following code sequence executes, what are the values of a, b, x, and y?

          x = &b;
          y = x;
          a = 10;
          b = 40;
          *x = 30;
          *y = *x * 3;
   
        a:
   
   
        b:
   
   
        x:
   
   
        y:
   
   
   
   
   

8. (12 points) Behold the following program that has been placed in a file named mystery.cpp. On the right are a set of Unix commands that will compile the program and run it on an input file. What is the output of the last Unix command?

   #include <iostream> #include <sstream> using namespace std; int mystery() { double num; int sum = 0; istringstream buffer; string input; while (cin >> input) { try { buffer.clear(); buffer.str(input); if (buffer >> num) { if (input.find('.') != string::npos) { throw num; } else { sum = sum + (int)num; } } else { cout << "Oops-that was not a number!\n"; throw (string) "input was not a number"; } cout << "input = " << num << endl; cout << "intermediate sum = " << sum << endl; } catch (double n) { cout << input << " is a double\n"; } } cout << "leaving sum\n"; return sum; } int main() { int result; try { result = mystery(); } catch (const string &e) { cout << e << endl; cout << "exiting program with an error\n"; return 1; } cout << "sum = " << result << endl; return 0; }

   UNIX> g++ mystery.cpp UNIX> cat input.txt 3.6 16 14.5 -5 Brad Smiley 20. Jill Nancy 17.4 50 UNIX> ./a.out < input.txt