conway/conway.c

/**
 * Yet another goddamn implementation of Conway's Game of Life.
 * I'm under the impression that every programmer must do this at some point,
 * and since I've been programming for a long time I guess I should get it out
 * of the way...
 *
 * (c) 2023 A.M. Rowsell
 * This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
 * If a copy of the MPL was not distributed with this file,
 * You can obtain one at https://mozilla.org/MPL/2.0/.
 */
// so many damn includes
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <wchar.h>
#include <locale.h>
#include <math.h>
#include <string.h>
#include <ctype.h>

void printGrid(int gridX, int gridY, int **arr, int generation) {
    char title[16];
    snprintf(title, 16, "Generation %d", generation);
    int spaces = ((float)gridX / 2.0F) - (strlen(title) / 2.0);
    if (spaces <= 0) {
        wprintf(L"%s\n", title);
    } else {
        for(int i = 0; i < spaces; i++) {
            wprintf(L" ");
        }
        wprintf(L"%s\n", title);
    }
    wprintf(L"%lc", 0x2554UL); // prints ╔
    for (int j = 0; j < gridX; j++) {
        wprintf(L"%lc", 0x2550UL); // prints ═
    }
    wprintf(L"%lc", 0x2557UL); // prints ╗
    wprintf(L"\n");
    for (int j = 0; j < gridY; j++) {
        wprintf(L"%lc", 0x2551UL); // prints ║
        for (int i = 0; i < gridX; i++) {
            wprintf(L"%lc", ((arr[i][j] == 1) ? 0x0023UL : 0x0020UL));
        }
        wprintf(L"%lc\n", 0x2551UL); // prints ║
    }
    wprintf(L"%lc", 0x255AUL); // prints ╚
    for (int j = 0; j < gridX; j++) {
        wprintf(L"%lc", 0x2550UL);
    }
    wprintf(L"%lc", 0x255DUL); // prints ╝

    return;
}

void doGeneration(int gridX, int gridY, int **arr) {
    // add up all live cells from [x-1][y-1] to [x+1][y+1]
    // if total is 3, cell becomes alive
    // if total is 4, cell retains state
    // any other, cell dies
    // also, all x/y are modulo gridX gridY so we get wraparound

    // temporary array to hold processed generation
    int *tempArr[gridX];
    for(int i = 0; i < gridX; i++) {
        tempArr[i] = (int *)malloc(sizeof(int)*gridY);
    }
    for(int i = 0; i < gridX; i++) {
        for(int j = 0; j < gridY; j++) {
            tempArr[i][j] = arr[i][j];
        }
    }
    // total keeps track of live neighbours
    int total = 0;
    for(int i = 0; i < gridY; i++) {
        // start of a line
        for(int j = 0; j < gridX; j++) {
            total = 0;
            // start of 9-cell eval
            for(int k = -1; k < 2; k++) {
                for(int l = -1; l < 2; l++) {
                    total += (arr[(j+k)%gridX][(i+l)%gridY] == 1) ? 1 : 0;
                }
            }
            if(total == 3) {
                tempArr[j][i] = 1;
            } else if (total == 4) {
                tempArr[j][i] = arr[j][i];
            } else {
                tempArr[j][i] = 0;
            }
        }
    }
    for(int i = 0; i < gridX; i++) {
        for(int j = 0; j < gridY; j++) {
            arr[i][j] = tempArr[i][j];
        }
    }
    // free all that memory
    for(int i = 0; i < gridX; i++) {
        free(tempArr[i]);
    }
    return;
}

int main(int argc, char *argv[]) {
    if (argc < 3) {
        printf("Usage: conway <xsize> <ysize> [seed]\n");
        exit(255);
    }
    setlocale(LC_CTYPE, "");
    int gridX = 0, gridY = 0, seed = 0, generation = 0;
    for (int i = argc - 1; i > 0; i--) {
        switch (i) {
        case 1:
            gridX = atoi(argv[i]);
            break;
        case 2:
            gridY = atoi(argv[i]);
            break;
        case 3:
            seed = atoi(argv[i]);
            break;
        }
    }
    if (seed == 0) {
        time_t t;
        srand((unsigned)time(&t));
    } else {
        srand(seed);
    }
    // dynamically allocate the 2D array, could be quite large!
    int *arr[gridX];
    for (int i = 0; i < gridX; i++) {
        arr[i] = (int*)malloc(gridY * sizeof(int));
    }
    // seed the array
    for (int i = 0; i < gridX; i++) {
        for (int j = 0; j < gridY; j++) {
            arr[i][j] = (rand() % 2 == 0) ? 1 : 0;
        }
    }
    // display initial grid
    printGrid(gridX, gridY, arr, generation);
    // loop doing gens until user decides to quit
    char choice[] = "y";
    while(strcmp(choice, "y") == 0) {
        wprintf(L"\n");
        generation++;
        doGeneration(gridX, gridY, arr);
        printGrid(gridX, gridY, arr, generation);
        wprintf(L"\nDo another generation? [y/n]: ");
        sprintf(choice, "%c", tolower(getchar()));
        getchar(); // consome the newline
    }
    // clean up allocated memory
    for(int i = 0; i < gridX; i++) {
        free(arr[i]);
    }
    return 0;
}