Game of Life - Programming Assignment #2

1. Programming Assignment #2 Professor Hugh C. LauerCS-2303 — System Programming Concepts Slides include materials from The C Programming Language, 2nd edition, by Kernighan and Ritchie,Absolute C++, by Walter Savitch, The C++ Programming Language, Special Edition, by BjarneStroustrup, and from C: How to Program, 5th and 6th editions, by Deitel and Deitel Assignment #2 -- Game of Life

2. Game of Life Occupied cell:– Empty cell:– x 0 or 1 neighbors organism diesof loneliness 3 neighbors birth of neworganism x 4 – 8 neighbors organism diesof overcrowding x x x 2 – 3 neighbors organism survives Published by John Conway,Scientific American, April 1970 Assignment #2 -- Game of Life

3. Game of Life Occupied cell:– Empty cell:– x 0 or 1 neighbors organism diesof loneliness 3 neighbors birth of neworganism x x 4 – 8 neighbors organism diesof overcrowding x x x 2 – 3 neighbors organism survives Assignment #2 -- Game of Life

4. Game of Life Occupied cell:– Empty cell:– x 0 or 1 neighbors organism diesof loneliness 3 neighbors birth of neworganism x x x 4 – 8 neighbors organism diesof overcrowding x x 2 – 3 neighbors organism survives Assignment #2 -- Game of Life

5. Game of Life Occupied cell:– Empty cell:– x 0 or 1 neighbors organism diesof loneliness 3 neighbors birth of neworganism x x x 4 – 8 neighbors organism diesof overcrowding x 2 – 3 neighbors organism survives Assignment #2 -- Game of Life

6. Programming Assignment #2 • Implement the Game of Life ./life X Y gens input print pause • x and y are size of grid • gens is # of generations to play • Game may halt earlier • input is name of file containing initial configuration • print is 'y' or 'n' indicating whether to print each generation • pause is 'y'or 'n'indicating whether to pause and wait for a keystroke between generations Assignment #2 -- Game of Life

7. Things you need to know • Command line arguments • K & R §5.10 • Allocating and freeing memory • malloc()and free()— K & R §B.5 • Reading from a file • K & R §7.5 • Two-dimensional arrays • K & R §5.7 Assignment #2 -- Game of Life

8. Game of Life • Read command line to determine size of board, number of generations, etc. • Dynamically allocate memory for three boards of the appropriate size • Using malloc() • Read input file an initialize one board • Play up to n generations • After each generation, test for termination — I.e., same as previous or 2nd previous generation • Print final generation • Optional pause and/or print after each generation for debugging purposes • Free dynamically allocated memory! Assignment #2 -- Game of Life

9. Program Organization • From this point on, every programmingassignment at WPI must be accompaniedby makefileor equivalent • Unless otherwise specified You may choose your own partition of the problem • See Lab1, Part3 • Must have • At least one .h file (your interface) • At least two .c files (together your program) • One makefile • Suggested partition • Life.c — main program, read input & initialize • Game.c — playing game, testing termination • Board.c— utility functions for printing boards, comparison, etc. • Life.h— interface with function headers, extern variable for any globals, etc. Assignment #2 -- Game of Life

10. Command line arguments int main(intargc, char *argv[]); • argc is number of arguments • argv[i] points to a null-terminated string representing the ith argument • intatoi(char*s)converts string to int • FILE*fopen(char*f,mode) opens a file named by character string Assignment #2 -- Game of Life

11. Allocating and freeing memory • May allocate arrays as automatic arrays (i.e., on The Stack) however • A better way is to request memory from The Heap • void*malloc(x*y*sizeof(char)) • Allocates this many bytes of storage, returns a pointer to it • voidfree(void *mallocedMemory) • Returns previously allocated memory to The Heap Assignment #2 -- Game of Life

12. Reading from a file • FILE *fopen(char *filename, char *mode); • Opens the file named for the string at filename • mode = "r"  read-only • Don’t forget to close using fclose() • FILE *f; • intfgets(f) reads one character from file f Assignment #2 -- Game of Life

13. Setting up two-dimensional array • Impossible to have dynamic 2D arrays in C • Instead • Allocate one array A of x*y elements • i.e., x rows of y elements each • All contiguously allocated in memory • Allocate a second array B of x pointers • Initialize ith pointer to &A[i*y*sizeof(element)); • To access element in ith row, jth column • B[i][j] Assignment #2 -- Game of Life

14. Two-dimensional array (continued) • char *B[x] • char A[x*y] ... ... ... ... ... ... ... A[0] A[1] A[2] A[3] A[4] A[y-1] Assignment #2 -- Game of Life

15. Two-dimensional array (continued) • char *B[x] • char A[x*y] j ... ... ... ... ... ... ... i Element B[i][j] Assignment #2 -- Game of Life

16. Program Organization • See Lab1, Part3 • Must have • At least one .h file (your interface) • At least two .c files (together your program) • One makefile • Suggested partition • Life.c — main program, read input & initialize • Game.c — playing game, testing termination • Board.c— utility functions for printing boards, comparison, etc. • Life.h— interface with function headers, extern variable for any globals, etc. Assignment #2 -- Game of Life

17. Game.c void PlayOne(int width, int height, char Old[][], char New[][]); • Loop thru Old array in two nested loops (rows and columns) • Corresponding value in New array depends upon nearest neighbors in Old • Suggested supporting function:– • char countNeighbors(Old[][], x, y, width, height); • Counts number of adjacent occupied cells, so that PlayOne() can determine cell value in New array • Two nested loops • Adjust for boundary conditions Assignment #2 -- Game of Life

18. Questions? Assignment #2 -- Game of Life