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C/C++ Users Group Library 1996 July
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C-C++ Users Group Library July 1996.iso
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vol_100
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101_01
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life.c
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1985-11-13
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/*
"LIFE"
The game invented by John Conway
This version written by Leor Zolman to exemplify
PROPER use of"goto" statements in C programs!
Note that the Universe is a toroid; i.e,
the left extreme is adjacent to the right extreme,
the top is adjacent to the bottom, and each corner
is adjacent to each other corner.
In other words, there ARE NO EXTREMES !!
Or, in a more physical illustration: If I could
take a peek straight ahead through the magical
eyepiece of an infinitely powerful telescope,
I'd be able to see the back of my brain-damaged
head....that is, of course, assuming no galaxies
or cats get in the way.
*/
#define CLEARS "\033E" /* string to clear the screen on
your terminal (Escape E does it
on mine. I strongly feel the
Heathkit/Zenith H19 terminal is
the best buy in the market for
serial console terminals.
Gratuitous plug ends.)
*/
#define TWIDTH 80 /* # of columns on your terminal */
#define XSIZE 60 /* length of cell array (max # of lines)*/
#define YSIZE 79 /* width of cell (terminal width - 1) */
/* To see how the toroid works,
try reducing XSIZE and YSIZE to
around 10 or 20. */
#define BOREDOM_THRESHOLD 5 /* This is how many generations
are allowed to pass without a
population change before Divine
intervention is called for. */
char *gets(); /* routine to accept a line of input */
char cell[XSIZE][YSIZE]; /* the universe matrix */
int minx, maxx, miny, maxy, pop, gen; /* misc. variables */
char doneflag; /* This goes true when we want to stop */
int boring; /* keeps count of how many generations
go by without a population change */
char center; /* 1 = center display; 0 = left
justify */
/*
The main driving routine, to accept random initial
and population configurations, and display their
evolution according to a proximity-based formula.
*/
main()
{
char c;
printf("%s\n\t *** BDS Life ***\n",CLEARS);
printf("\nDo you wish to have the display centered\n");
printf(" (and thereby slowed down a bit) (y/n) ?");
center = toupper(getchar()) == 'Y';
putchar('\n');
for (;;) {
clear();
setup();
if (!pop) break;
adjust();
display();
while (pop) {
adjust();
dogen();
if (kbhit()) {
getchar();
printf("\nThe Wrath Of God Strikes!!!!! KA-BEEP!\7\n");
break;
}
display();
if (boring == BOREDOM_THRESHOLD) {
boring++;
printf("\nNo change in population for");
printf(" %d ",BOREDOM_THRESHOLD);
printf("generations. Abort (y/n) ");
c = toupper(getchar());
putchar('\n');
if (c == 'Y') break;
}
if (doneflag) break;
}
}
}
/* Initialize the cell matrix to all dead */
clear()
{
setmem(cell,(XSIZE*YSIZE),0);
}
/* Get initial set-up from user */
setup()
{
char c;
int y;
char string[YSIZE], *ptr;
y = pop = gen = minx = maxx = miny= maxy = 0;
boring = 0;
printf("\nEnter initial configuration (single period to end):\n");
while (*gets(string) != '.') {
ptr = string;
while (*ptr) {
if ( *ptr++ != ' ') {
cell[maxx][y] = 10;
++pop;
}
++y;
if (y==YSIZE) {
printf("Truncated to %d chars\n",
YSIZE); break;
}
}
--y;
++maxx;
if (y>maxy) maxy = y;
if (maxx==XSIZE) break;
y = 0;
}
--maxx;
}
/* Display the current generation */
display()
{
int i,j,k,l,j9;
char c;
if (!pop) {
printf("\nLife ends at %d\n",gen);
return;
}
if(minx && prow(minx-1)) minx--;
if(miny && pcol(miny-1)) miny--;
if ((maxx < (XSIZE-1)) && prow(maxx+1)) maxx++;
if((maxy<(YSIZE-1)) && pcol(maxy+1))maxy++;
while (!prow(minx)) minx++;
while (!prow(maxx)) maxx--;
while (!pcol(miny)) miny++;
while (!pcol(maxy)) maxy--;
puts(CLEARS);
if (center) {
i = (TWIDTH-33)/2;
for (j = 0; j<i; j++) putchar(' ');
}
printf("generation = %1d population = %1d\n",
gen,pop);
++gen;
j9 = maxy - miny + 1;
for (i = minx; i<=maxx; i++) {
if (center && j9<TWIDTH) {
l = (TWIDTH-j9)/2;
for (k = 0; k<l; k++) putchar(' ');
}
for (j=miny; j<=maxy; j++)
putchar(cell[i][j] ? '*' : ' ');
if (i != maxx) putchar('\n');
}
}
/* Test if given column is populated */
pcol(n)
{
int i,hi;
hi = (maxx == (XSIZE-1)) ? maxx : maxx+1;
for (i = minx ? minx-1 : minx; i<=hi; ++i)
if (cell[i][n]) return 1;
return 0;
}
/* Test if given row is populated */
prow(n)
{
int i,hi;
hi = (maxy == (YSIZE-1)) ? maxy : maxy+1;
for (i = miny ? miny-1 : miny; i<=hi; ++i)
if (cell[n][i]) return 1;
return 0;
}
/*
Compute next generation. Algorithm used is a two-pass
cuteness suggested to me by Ward Christensen (he uses
it on a machine-language version on a 1024 character
display, and it cranks out 20 generations a second at
2 MHz.)
The algorithm uses the low order 3 bits of each 1-byte
cell as a neighbor count. The first pass finds all live
cells and increments the count of each of the 8 neighbors
of such live cells. For the first pass, dead cells are
totally ignored. The second pass then comes along and
checks the counts off all cells within the active square
to determine who lives and who dies. Note that this is a
significant improvement over the "obvious" method of
examining all 8 neighbors of each and every cell, dead
or alive, in the array.
*/
dogen()
{
int i,j,i2,j2;
int bigflag;
int k,l;
int oldpop;
char c;
int pass;
doneflag = 1;
oldpop = pop;
bigflag = (minx<2 || maxx>(XSIZE-3) ||
miny<2 || maxy>(YSIZE-3)) ;
i2 = (maxx==(XSIZE-1)) ? maxx : maxx+1;
j2 = (maxy==(YSIZE-1)) ? maxy : maxy+1;
for (pass = 0; pass < 2; pass++)
for (i=minx ? minx-1 : minx; i<=i2; ++i)
for (j=miny ? miny-1 : miny; j<=j2; ++j) {
c = cell[i][j];
if (!pass) {
if (c >= 10)
if (bigflag)
for (k = -1; k <= 1; k++)
for (l = -1; l <= 1; l++)
cell[mod(i+k,XSIZE)][mod(j+l,YSIZE)]++;
else
for (k = -1; k<=1; k++)
for (l = -1; l <= 1; l++)
cell[i+k][j+l]++;
}
else
if (c > 10)
if (c < 13 || c > 14) {
cell[i][j] = 0;
pop--;
doneflag = 0;
}
else cell[i][j] = 10;
else
if (c == 3) {
cell[i][j] = 10;
pop++;
doneflag = 0;
}
else cell[i][j] = 0;
}
if (pop == oldpop) boring++;
else boring = 0;
}
int mod(a,b)
{
if (a<0) return b+a;
if (a<b) return a;
return a-b;
}
/* If we're about to run off the matrix, adjust accordingly (if possible) */
adjust()
{
adjx(); /* for overflow in x direction */
adjy(); /* and also in y direction */
}
/* Adjust vertical position */
adjx()
{
int delta, i,j;
int savdelta;
if (maxx - minx + 1 > XSIZE-2) return;
if (minx==0) {
delta = (XSIZE-maxx)/2+maxx;
savdelta = delta;
for (i=maxx; i >= 0; --i) {
for (j=miny; j<=maxy; ++j) {
cell[delta][j] = cell[i][j];
cell[i][j] = 0;
}
--delta;
}
minx = delta+1;
maxx = savdelta;
}
if (maxx == (XSIZE-1)) {
delta = minx/2;
savdelta = delta;
for (i=minx; i<XSIZE; ++i) {
for (j=miny; j<=maxy; ++j) {
cell[delta][j] = cell[i][j];
cell[i][j] = 0;
}
++delta;
}
maxx = delta-1;
minx = savdelta;
}
}
/* Adjust horizontal position */
adjy()
{
int delta, i, j;
int savdelta;
if (maxy - miny + 1 > YSIZE -2) return;
if (miny == 0) {
delta = (YSIZE-maxy)/2+maxy;
savdelta = delta;
for (i=maxy; i>=0; --i) {
for (j=minx; j<=maxx; ++j) {
cell[j][delta] = cell[j][i];
cell[j][i] = 0;
}
--delta;
}
miny = delta+1;
maxy = savdelta;
}
if (maxy == (YSIZE-1)) {
delta = miny/2;
savdelta = delta;
for (i=miny; i<YSIZE; ++i) {
for (j=minx; j<=maxx; ++j) {
cell[j][delta] = cell[j][i];
cell[j][i] = 0;
}
++delta;
}
maxy = delta -1;
miny = savdelta;
}
}
/*
This is done so that the Wrath Of God doesn't mess up the
display:
*/
putchar(c)
char c;
{
putch(c);