Dexter's story

#include "stdio.h"
#include "process.h"
#include "time.h"
#define scale 50
#define maxpath 255

unsigned long random(unsigned long i)//pseudorandom number generator
{
    if(i && time(0)%2) return (unsigned long)(i>>1)|(((i^(i>>10)^(i>>30)^(i>>31))&1)<<31);
    else return (unsigned long)(i*1103515245+12345)%0x100000000;
}

void grow(char a[])//determines the growth of whole grid
{
    int i;
    char b[scale*scale]={}, j;//j will be used as a number
    for(i=0;i<scale*scale;i++) if(a[i]) for(j=0;j<9;j++)
        if(j!=4 && i/scale+j/3!=0 && i%scale+j%3!=0 && i/scale+j/3<=scale && i%scale+j%3<=scale)
            b[(i/scale-1+j/3)*scale+i%scale-1+j%3]++;//if the cell is alive, neighboring grid's count goes up
    for(i=0;i<scale*scale;i++)
    {
        if(b[i]==3 || a[i] && b[i]==2) a[i]=1;//lives&generated when 3 cells are neighboring, lives when 2 cells are neighboring
        else a[i]=0;       
    }
}

void printarr(char a[],char live,char dead)//prints grid status
{
    int i;
    for(i=0;i<scale*scale;i++)
    {
        if(i%scale==0&&i!=0) printf("\n");//new line is entered when nonzero i is a multiple of scale
        if(a[i]) printf("%c", live);
        else printf("%c", dead);
    }
}

int locate(char loc[])
{
    int i;
    printf("File location(length at most %d):\n", maxpath);
    while(1)//loop until input is proper
    {
        for(i=0;i<=maxpath;i++) loc[i]=0;//initialize string
        gets(loc);
        if(loc[0]) break;
    }
    if(loc[maxpath]!=0) {printf("Path is too long.\n"); return 0;}
    return 1;
}

int fileread(char a[], char loc[])//opens a file, then returns alive cells to the grid
{
    FILE *fp;
    char alive[2];
    int i,c;
    printf("Input from a text file.\n");
    if(!locate(loc)) {system("pause"); return 0;}
    if((fp=fopen(loc,"r"))==0) {printf("File not found.\n"); system("pause"); return 0;}
    while(1)
    {
        printf("Reading grid from <%s>\nWhich character represents alive cells?\n",loc);
        scanf("%s",alive);//calling by %c somehow causes an error, so I used %s
        if(alive[1]!=0) continue;
        else break;
    }
    loc[0]=0;
    for(i=0;i<scale*scale;i++)
    {
        if((c=fgetc(fp))==alive[0]) {a[i]=1; loc[0]=1;}
        else if(c=='\n') if(loc[0]&&!(i%scale))i--;//fixes the problem of reading its output file differently
        else i=scale*((i/scale)+1)-1;//when line is changed, grid line is changed
        else if(c==EOF) break;//when file has ended, escape the loop
        else loc[0]=1;//fixes the problem of reading its output file differently
    }
    printf("Grid is loaded.\n");
    fclose(fp);
    return 1;
}

int filewrite(char a[],char loc[],char live, char dead, int time)//saves the grid onto the output file
{
    FILE *fp;
    int i;
    printf("Export grid to an output file.\n");
    if(!locate(loc)) return 0;
    printf("Saving the last grid in <%s>...\n",loc);
    if((fp=fopen(loc,"w"))==0){printf("Save error: cannot open file.\n"); return 0;}
    for(i=0;i<scale*scale;i++)
    {
        if(i%scale==0&&i)if(fputc('\n',fp)==EOF)goto writeerror;
        if(a[i]) {if(fputc(live,fp)==EOF)goto writeerror;}
        else if(fputc(dead,fp)==EOF)goto writeerror;
    }
    if(fprintf(fp,"\n\n Time:%d",time)<0) goto writeerror;
    fclose(fp); printf("Saved.\n"); return 1;
writeerror:
    printf("Save error: cannot write.\n"); fclose(fp); return 0;
}

void generate(char a[],int n)//generates random grid based on approximate cell number
{
    int i;
    unsigned long j=7;
    if(n<=0) n=random(time(0))%(scale*scale);
    else n=n%(scale*scale);
    printf("Approximate cell number is %d.\n",n);
    for(i=0;i<n;i++) {j=random(j); a[j%(scale*scale)]=1;}
}

int main()//main function
{
    int i,time;
    char a[scale*scale]={},loc[maxpath+1]={}, cell[2];
    printf("John Conway's Game of Life - on a grid of %d x %d\nFor how long would you like to run the game?\n", scale, scale);
    scanf("%d", &time);
    gets(loc);//absorbs input error(such as writing a string)
    while(1)//determining representation of cells
    {
        printf("An alive cell would look like: \n");
        scanf("%s", cell);//calling by %c somehow causes an error, so I used %s
        if(cell[1]!=0) continue;
        printf("Alive cell is shown as %c. Enter 1 to confirm.\n",cell[0]);
        scanf("%d", &i);
        if(i) break;
    }
    while(1)//input determination
    {
        printf("Do you wish to start from any input file?(1 to read from an input file)\n");
        scanf("%d", &i);
        if(i!=1) break;
        else if(fileread(a,loc)) break;
    }
    if(i!=1)//random input
    {
        printf("Choose approximate cell number(1~%d, 0 for random selection).\n", scale*scale-1);
        scanf("%d",&i);
        generate(a,i);
    }
    system("pause");
    i=0; while(1)
    {
        system("cls");
        printarr(a,cell[0],' ');
        printf("\n\n Time:%d\n",i);
        system("pause");
        if(i>=time) break;
        grow(a);
        i++;
    }
    printf("\n\nEnd of simulation.\n");
    while(1)
    {
        printf("Do you wish to save the last grid?(1 to save)\n");
        scanf("%d",&i);
        if(i!=1) break;
        else if(filewrite(a,loc,cell[0],' ',time)) break;
    }
    printf("Programmed by Dexter.\n  http://dexterstory.tistory.com\n");
    system("pause");
    return 0;
}