prototype.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include <time.h>
   5 #include <unistd.h>
   6
   7 #define COLS 80
   8 #define ROWS 25
   9
  10 #define DEAD ' '
  11 #define ALIVE '#'
  12
  13 #define INIT_RATIO 4
  14
  15 #define STR(x) _STR(x)
  16 #define _STR(x) #x
  17
  18 static void clearscr() { printf("\e[1;1H\e[2J"); }
  19
  20 static void print_row(char row[COLS]) { printf("%." STR(COLS) "s\n", row); }
  21
  22 static void print_grid(char grid[COLS * ROWS]) {
  23   for (int i = 0; i < ROWS; i++)
  24     print_row(grid + i * COLS);
  25 }
  26
  27 static void init_grid(char grid[COLS * ROWS]) {
  28   for (int i = 0; i < COLS * ROWS; i++) {
  29     if (rand() % INIT_RATIO)
  30       grid[i] = DEAD;
  31     else
  32       grid[i] = ALIVE;
  33   }
  34 }
  35
  36 static char get_state(char grid[COLS * ROWS], int row, int col) {
  37   if (row < 0 || row >= ROWS || col < 0 || col >= COLS)
  38     return DEAD;
  39
  40   return grid[row * COLS + col];
  41 }
  42
  43 static int alive_neighbours(char grid[COLS * ROWS], int idx) {
  44   int row = idx / COLS;
  45   int col = idx % COLS;
  46   int neighbours = 0;
  47
  48   for (int i = -1; i <= 1; i++)
  49     for (int j = -1; j <= 1; j++)
  50       if (get_state(grid, row + i, col + j) == ALIVE)
  51         neighbours++;
  52
  53   if (get_state(grid, row, col) == ALIVE)
  54     neighbours--;
  55
  56   return neighbours;
  57 }
  58
  59 static char next_state(char grid[COLS * ROWS], int idx) {
  60   int n = alive_neighbours(grid, idx);
  61
  62   if (get_state(grid, idx / COLS, idx % COLS) == ALIVE) {
  63     if (n < 2 || n > 3)
  64       return DEAD;
  65
  66     return ALIVE;
  67   }
  68
  69   if (n == 3)
  70     return ALIVE;
  71
  72   return DEAD;
  73 }
  74
  75 static void update_grid(char grid[COLS * ROWS]) {
  76   char new[COLS * ROWS];
  77
  78   for (int i = 0; i < COLS * ROWS; i++)
  79     new[i] = next_state(grid, i);
  80
  81   memcpy(grid, new, COLS * ROWS);
  82 }
  83
  84 int main() {
  85   char grid[COLS * ROWS];
  86
  87   srand(time(0));
  88   init_grid(grid);
  89
  90   do {
  91     clearscr();
  92     print_grid(grid);
  93     update_grid(grid);
  94   } while (getchar() != 'q');
  95
  96   return 0;
  97 }