CS105: Introduction to Computer Programming: C++

Assignment #2: Introduction to the Game of Life


Tuesday, February 9th at NOON


This is an assignment where you will dive into using arrays. You'll have to write several functions to play the Game of Life and compile and run your code.

The Game of Life was developed by John Conway in 1970 to simulate cellular automaton. The game board is a 2-dimensional grid. The game has an initial state specified, then proceeds by evolving the grid through "generations". Each cell in the grid can be either "live" or "dead". Given an initial state of the board, the next generation of the board is determined by the status of each cells' neighbors which include cells directly horizontally, vertically, and diagonally adjacent. An internal cell has 8 total neighbors. The evolution of the board is created by applying the following rules to all cells simultaneously:

  1. A live cell with fewer than 2 live neighbors dies.
  2. A live cell with more than 3 live neighbors dies.
  3. A live cell with 2 or 3 live neighbors lives on to the next generation.
  4. A dead cell with exactly 3 neighbors becomes a live cell.
Here is an example initial 5 x 5 board, and the 1st generation where "*" is live and "." is dead:
. . . . .
. * * * .
* * * . .
. . . . .
. . . . .

. . * . .
* . . * .
* . . * .
. * . . .
. . . . .

To get the initial board, you will take input from standard input (cin) . The initial board will be specified in a file, which you will pipe into your program, just as in assignment 1, so you can use standard in. The file, LifeZero.in, will first have the number of rows, then the number of columns specified. These will be followed by a number of lines equal to the number of rows specified. Each row will be filled with a number of characters (separated by spaces) equal to the number of columns specified. The characters will be either '*' or '.', meaning alive or dead, respectfully. You can create your board initially using this state. Each generation, you print your board in the same manner (you do not have to print the dimensions each time). You print each row to standard out (cout) , with characters separated by a space , and print a newline at the end of each row to start the next row. At the end of each whole board printed (each generation), print a blank line to clearly separate generations from each other.


These instructions assume that you're doing development on the CS department linux machines. I recommend using the CS department linux machines, but if you feel more comfortable using another development platform, that's fine. Eventually, you'll have to use the CS department machines to submit the assignment, but you can develop on any machine you're comfortable with. Just make sure to test your code on the department machines before turning it in!
  1. If you don't have a CS department account, you should request a new account.
  2. Log on to a CS department linux machine using your CS department login. Make sure you log into a Linux machine, not a Sun machine!
  3. Start up XWindows by typing
    If you're new to linux, you might want to get a friend to help you or come by office hours. Getting used to a new operating system can take some time.
  4. Open up a terminal window and make a new directory for this assignment called assignment2:
    mkdir assignment2
    And change to that directory:
    cd assignment2
    Now use your favorite text editor to edit this file I created to get you started called gameOfLife.cpp.
  5. First, make sure your name is in the top of the file! Write some code inside gameOfLife.cpp (without using dynamic allocation or pointers - no "*"!) that plays the game of life, taking input from a file such as LifeZero.in (You can create others to test with and I will use other files to grade with):
    1. You will define 2 printLife functions that print the 2-dimensional gameboard of the game of life. One will use an array declared to be 2D (with fixed 2nd dimension) and the other will store the 2D board in a 1 dimensional array and use that.
    2. You will define 2 playLife functions that play the game of life, i.e. evolve the 2D gameboard from one generation to another. These take input arrays similarly to the 2 printLife functions above.
    3. You will also have to add some code to main to declare and initialize arrays and test your game of life. Notice the constant default 2nd dimension of your 2D arrays is specified at the top of the cpp file, and thus can be used in function prototypes. Although the input file specifies the number of columns, just assume (or print an error if untrue) that the number of columns specified in your input file equals that defaultNumColumns. Also, for "part 2" of the assignment, you can initialize your board with the same contents of the board initialized in "part 1", taken from cin. Also notice that you should print the initial board once (followed by a blank line). Then you should go through 3 iterations of calling your playLife function to evolve the board, then calling your printLife function to print it post evolution. Make sure there is a blank line in between each board generation.
  6. Compile and run your code:
      computer% g++ -Wall -Werror -o life gameOfLife.cpp
      computer% ./life < LifeZero.in
  7. When you're happy with your code, use the turnin program to submit your gameOfLife.cpp file. Use jbsartor as the grader and assign2 as the assignment name (if you choose to take mulligans, use assign2Mulligan).
    turnin --submit jbsartor assign2 gameOfLife.cpp
    OR if late:
    turnin --submit jbsartor assign2Mulligan gameOfLife.cpp
    You can turn in your file as many times as you want - I will only take the last one submitted.

Submission Checklist

Extra Credit (+5%)

Answer the following questions in written form in comments after your name at the top of gameOfLife.cpp.