UMBC CMSC201, Computer Science I, Fall '97

Project 4: The Game of Life

Originally Due: Wednesday, November 26, 1997

Bonus Date: Wednesday, November 26, 1997 (10 point bonus)

New Due Date: Friday, November 28, 1997, by midnight

The Game of Life, invented by John H. Conway, is supposed to model the population laws for birth, survival, and death (see Scientific American, October 1970, p. 120). It really isn't a "game", but a simulation of population growth that is displayed over time. The basic assignment is to write a program that simulates population growth over time governed by specific rules. For extra credit, you can add code that lets the user play it as a game against the computer, but more about that later.

This project will give you practice using two-dimensional arrays, passing an array to a function, pointers, getting input from the user using scanf, and reading from a file using ansi C file-handling functions.

You are not allowed to use any of the Roberts' libraries for this project

Description of the Game of Life

You will be working with a population that is contained within a 15 X 15 square-unit area (225 squares), known as the board. Each square can be empty or it can contain an X indicating the presence of an organism. Each square, except for the border squares, has eight neighbors; North, South, East , West and also NorthEast, SouthEast, SouthWest, NorthWest.

Generation 1

The next generation of organisms is determined according to the following criteria:

1. Birth - an organism will be born at each empty location that has exactly 3 neighbors
2. Death - an organism with 4 or more organisms as neighbors will die from overcrowding. An organism with fewer than 2 neighbors will die from lonliness.
3. Survival - an organism with 2 or 3 neighbors will survive to the next generation. Generations 2 and 3 for this sample segment of the board are shown below:

Generation 2

Generation 3

The initial population, consisting of the presence or absence of an individual for each square-unit location are found in the file "population.dat". Basically, the file contains 225 integer values separated by whitespace, where a 1 indicates the existance of an organism at that location and a 0 means there is no life there. You may assume that none of the integers found in the file will be anything other than a 0 or a 1. I guarantee that there are 225 integers in the file, so checking for EOF is not necessary. Here is the contents of the file:

   
   1 1 1 0 0 0 0 0 0 0 0 0 0 1 1
   1 1 1 0 0 0 0 1 0 0 0 1 1 0 1
   1 1 0 0 0 0 0 0 0 0 0 0 1 0 0
   0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
   0 0 0 0 0 1 0 0 0 0 0 0 0 0 1
   0 0 0 0 1 1 1 0 0 0 0 0 0 0 0
   0 0 0 0 0 1 0 0 0 0 0 0 0 0 0
   0 0 0 0 0 0 0 0 0 0 1 1 0 0 0
   0 0 0 0 0 0 0 0 0 0 1 1 0 0 0
   0 0 1 0 0 0 0 0 0 0 0 0 1 0 0
   0 0 1 0 0 0 0 0 0 0 0 1 1 0 0
   0 0 0 0 0 0 0 0 0 0 0 0 1 0 1
   0 0 0 0 0 0 0 1 0 0 0 0 1 0 0
   1 0 0 0 0 0 0 0 0 0 0 0 0 0 1

You will be reading the values found in the file into a two-dimensional array and then display the array, labelling it Time: 0. Next you will need to calculate the next generation and store it in a new array, copy the new array into the original array and display it, labelling it Time: 1. This process could go on indefinitely and so "the game of life" is commonly used as a screen saver. For this project, you will ask the user to say how many time intervals should pass between displaying the array, and also the total amount of time for the entire simulation.

For the input file shown above, the original array should be displayed like this:

Time: 0
   
XXX          XX
XXX    X   XX X
XX          X  
               
               
     X        X
    XXX        
     X         
          XX   
          XX   
  X         X  
  X        XX  
            X X
       X    X  
X             X

More details

• To begin, you will need to read in the data from the data file, population.dat You will NOT be able to use unix redirection for this program, since you will also need to ask the user to input information. You will need to open the file for reading using fopen, read the integers in the file using fscanf, placing them into a two-dimensional array of integers as you go, and then close the file.
• For each unit of time, whether or not an organism exists in each square-unit area must be recalculated, using the rules for birth, death and survival shown above.
• If you view the results of the simulation after each unit of time, the change in the population is less noticeable than if you wait for several time units before viewing. Since the user needs to see and interpret the results of the simulation, the user needs to have control over how often he views the results and over how long a period of time to run the simulation. The period of time between the printing of charts I will refer to as the time interval. The period of time for the entire simulation I will refer to as total time. You must ask the user to input both the time interval and the total time.

You are REQUIRED to have a function called GetInput which gets both of these items from the user. Since this function has to "return" two pieces of data, the function must have pointers as arguments. Here is the function prototype you are to use for this function :

    void GetInput (int *intervalPtr, int *timePtr);

• Although no error checking is necessary for the data coming in from the file, error checking of the user input is required.

• You will be graded on your design and on the efficiency of the program, as well as the correctness of the program, documentation and style.
• Hints
• Since every square will be altered by its neighbors, and you must use the original values of each square for the calculations, you cannot just move through the array making changes as you go. This would give erroneous results. A second two-dimensional array needs to be made that will hold either the presence or absence of an organism that is being calculated for each square, while the original array is still intact to provide the values needed for the calculations.

The data file

The data file for this project is called population.dat and it is found in my 201 directory. You should copy this file into your own directory. The executable and this data file need to be in the same directory. Here's how:
Change directory until you are in the directory where you will write your code and have the executable, then type the following command at the unix prompt.

cp ~sbogar1/201/population.dat population.dat

  

What to Turn In

You must use separate compilation for this project and should have a file, called proj4.c, that contains only the function main(). You should also have an life.c and life.h, that contain functions related to the game of life and the prototypes for those functions, respectively. You may, of course, have other .c and .h files, as you see fit. Possibly util.c and util.h if you need them. Submit as follows:

submit cs201 proj4 proj4.c life.c life.h

The order in which the files are listed doesn't matter. However, you must make sure that all files necessary to compile your project are listed.

There will be extra credit available on this project. More about the extra credit portion will follow in a separate document.