Use NULL instead of (FOO *)0, it's easier to read.

src/lib/as/as_cache.c

@@ -85,9 +85,9 @@ as_add_cachepath(struct as_data *adp)
     /* Note we will only allocate this once.  Afterwards, we just keep
      * zeroing it since it's rather small and we don't need to re-allocate
      * each time. */
-    if (fromhead == (struct as_frompath **)0) {
+    if (fromhead == NULL) {
 	fromhead = calloc(1, sizeof(struct as_frompath *) * WORLD_Y);
-	if (fromhead == (struct as_frompath **)0)
+	if (fromhead == NULL)
 	    return;
     }
 
@@ -143,7 +143,7 @@ as_clear_cachepath(void)
     int i, j;
 
     /* Cache not used yet :) */
-    if (fromhead == (struct as_frompath **)0)
+    if (fromhead == NULL)
 	return;
 
     for (j = 0; j < WORLD_Y; j++) {
@@ -181,7 +181,7 @@ as_find_cachepath(coord fx, coord fy, coord tx, coord ty)
 	return NULL;
 
     /* Do we have any cached? */
-    if (fromhead == (struct as_frompath **)0)
+    if (fromhead == NULL)
 	return NULL;
 
     /* Yes! */

src/lib/commands/best.c

@@ -65,7 +65,7 @@ best(void)
 	    if (s2.sct_own != player->cnum)
 		continue;
 	    s = BestLandPath(buf, &s1, &s2, &cost, MOB_ROAD);
-	    if (s != (s_char *)0)
+	    if (s)
 		pr("Best path from %s to %s is %s (cost %1.3f)\n",
 		   xyas(s1.sct_x, s1.sct_y, player->cnum),
 		   xyas(s2.sct_x, s2.sct_y, player->cnum), s, cost);

src/lib/commands/bomb.c

@@ -413,7 +413,7 @@ comm_bomb(struct emp_qelem *list, struct sctstr *target)
 	pr("some %s\n", ip->i_name);
     }
     for (;;) {
-	ip = whatitem((s_char *)0, "commodity to bomb? ");
+	ip = whatitem(NULL, "commodity to bomb? ");
 	if (player->aborted)
 	    return;
 	if (!ip)

src/lib/commands/dist.c

@@ -102,7 +102,7 @@ dist(void)
 
 	path = BestDistPath(buf, &sect, &dsect, &move_cost, MOB_ROAD);
 
-	if (path == (s_char *)0) {
+	if (!path) {
 	    pr("No owned path from %s to %s.\n",
 	       xyas(dsect.sct_x, dsect.sct_y, player->cnum),
 	       xyas(sect.sct_x, sect.sct_y, player->cnum));

src/lib/commands/navi.c

@@ -224,9 +224,9 @@ nav_map(int x, int y, int show_designations)
     int i;
     /* Note this is not re-entrant anyway, so we keep the buffers
        around */
-    static u_char *bitmap = (u_char *)0;
+    static u_char *bitmap = NULL;
-    static s_char *wmapbuf = (s_char *)0;
+    static s_char *wmapbuf = NULL;
-    static s_char **wmap = (s_char **)0;
+    static s_char **wmap = NULL;
     s_char what[64];
     int changed = 0;
 
@@ -244,7 +244,7 @@ nav_map(int x, int y, int show_designations)
 		wmap[i] = &wmapbuf[MAPWIDTH(1) * i];
 	} else if (wmap) {
 	    free(wmap);
-	    wmap = (s_char **)0;
+	    wmap = NULL;
 	}
     }
     if (!bitmap)

src/lib/commands/path.c

@@ -61,8 +61,8 @@ path(void)
     s_char *pp, *p;
     /* Note this is not re-entrant anyway, so we keep the buffers
        around */
-    static s_char *mapbuf = (s_char *)0;
+    static s_char *mapbuf = NULL;
-    static s_char **map = (s_char **)0;
+    static s_char **map = NULL;
     double move_cost;
     s_char buf[1024];
 
@@ -75,7 +75,7 @@ path(void)
     }
     getsect(sect.sct_dist_x, sect.sct_dist_y, &dsect);
     pp = BestDistPath(buf, &sect, &dsect, &move_cost, MOB_ROAD);
-    if (pp == (s_char *)0) {
+    if (!pp) {
 	pr("No path possible from %s to distribution sector %s\n",
 	   xyas(sect.sct_x, sect.sct_y, player->cnum),
 	   xyas(dsect.sct_x, dsect.sct_y, player->cnum));
@@ -90,7 +90,7 @@ path(void)
 		map[i] = &mapbuf[MAPWIDTH(3) * i];
 	} else if (map) {
 	    free(map);
-	    map = (s_char **)0;
+	    map = NULL;
 	}
     }
     if (!mapbuf || !map) {

src/lib/commands/retr.c

@@ -67,9 +67,9 @@ retr(void)
     if (player->argp[2] != NULL)
 	pq = getstarg(player->argp[2], "Retreat path? ", buf1);
     else
-	pq = (s_char *)0;
+	pq = NULL;
 
-    if (pq != (s_char *)0) {
+    if (pq != NULL) {
 	fl = getstarg(player->argp[3],
 		      "Retreat conditions [i|t|s|h|b|d|u|c]? ", buf2);
 	if (!fl)
@@ -129,7 +129,7 @@ retr(void)
     }
 
     if (rflags == -1)
-	pq = (s_char *)0;
+	pq = NULL;
 
     zero = (rflags == -1);
     if (zero)
@@ -141,7 +141,7 @@ retr(void)
 	if (zero)
 	    memset(ship.shp_rpath, 0, sizeof(ship.shp_rpath));
 
-	if (pq != (s_char *)0) {
+	if (pq != NULL) {
 	    strncpy(ship.shp_rpath, pq, sizeof(ship.shp_rpath));
 	    putship(ship.shp_uid, &ship);
 	}
@@ -215,8 +215,8 @@ lretr(void)
     if (player->argp[2] != NULL)
 	pq = getstarg(player->argp[2], "Retreat path? ", buf1);
     else
-	pq = (s_char *)0;
+	pq = NULL;
-    if (pq != (s_char *)0) {
+    if (pq != NULL) {
 	fl = getstarg(player->argp[3], "Retreat conditions [i|h|b|c]? ",
 		      buf2);
 	if (!fl)
@@ -256,7 +256,7 @@ lretr(void)
     }
 
     if (rflags == -1)
-	pq = (s_char *)0;
+	pq = NULL;
 
     zero = (rflags == -1);
     if (zero)
@@ -268,7 +268,7 @@ lretr(void)
 	if (zero)
 	    memset(land.lnd_rpath, 0, sizeof(land.lnd_rpath));
 
-	if (pq != (s_char *)0) {
+	if (pq != NULL) {
 	    strncpy(land.lnd_rpath, pq, sizeof(land.lnd_rpath));
 	    putland(land.lnd_uid, &land);
 	}

src/lib/commands/rout.c

@@ -67,9 +67,9 @@ rout(void)
     s_char buf1[1024];
     /* Note this is not re-entrant anyway, so we keep the buffers
        around */
-    static s_char *mapbuf = (s_char *)0;
+    static s_char *mapbuf = NULL;
-    static s_char **map = (s_char **)0;
+    static s_char **map = NULL;
-    static s_char *buf = (s_char *)0;
+    static s_char *buf = NULL;
     int i;
 
     if ((ip = whatitem(player->argp[1], "What item? ")) == 0)
@@ -98,7 +98,7 @@ rout(void)
 		map[i] = &mapbuf[MAPWIDTH(3) * i];
 	} else if (map) {
 	    free(map);
-	    map = (s_char **)0;
+	    map = NULL;
 	}
     }
     if (!buf)

src/lib/commands/sect.c

@@ -62,8 +62,8 @@ sct(void)
     s_char buf[1024];
     /* Note this is not re-entrant anyway, so we keep the buffers
        around */
-    static s_char *mapbuf = (s_char *)0;
+    static s_char *mapbuf = NULL;
-    static s_char **map = (s_char **)0;
+    static s_char **map = NULL;
 
     nsect = 0;
     if (player->argp[1] == NULL) {
@@ -90,7 +90,7 @@ sct(void)
 		map[i] = &mapbuf[MAPWIDTH(1) * i];
 	} else if (map) {
 	    free(map);
-	    map = (s_char **)0;
+	    map = NULL;
 	}
     }
     if (!mapbuf || !map) {

src/lib/commands/surv.c

@@ -70,8 +70,8 @@ surv(void)
     s_char *str;
     /* Note this is not re-entrant anyway, so we keep the buffers
        around */
-    static s_char *mapbuf = (s_char *)0;
+    static s_char *mapbuf = NULL;
-    static s_char **map = (s_char **)0;
+    static s_char **map = NULL;
 
     nsect = 0;
     if ((ptr = getstarg(player->argp[1], "commodity or variable? ", buf)) == 0)
@@ -109,7 +109,7 @@ surv(void)
 		map[i] = &mapbuf[MAPWIDTH(1) * i];
 	} else if (map) {
 	    free(map);
-	    map = (s_char **)0;
+	    map = NULL;
 	}
     }
     if (!mapbuf || !map) {

src/lib/commands/terr.c

@@ -78,7 +78,7 @@ terr(void)
 	    sprintf(prompt, "%s %d%% %s  territory? ",
 		    xyas(nstr.x, nstr.y, player->cnum),
 		    sect.sct_effic, dchr[sect.sct_type].d_name);
-	    if ((p = getstarg((s_char *)0, prompt, buf)) == 0)
+	    if ((p = getstarg(NULL, prompt, buf)) == 0)
 		return RET_FAIL;
 	    if (!check_sect_ok(&sect))
 		return RET_FAIL;

src/lib/common/bestpath.c

@@ -117,8 +117,8 @@ int dy[6] = { 0, -1, -1, 0, 1, 1 };
  * would be slow.  And, since world size only changes at init
  * time, we can do this safely.
  */
-static unsigned int *mapbuf = (unsigned int *)0;
+static unsigned int *mapbuf;
-static unsigned int **mapindex = (unsigned int **)0;
+static unsigned int **mapindex;
 
 s_char *
 bestownedpath(s_char *bpath,

src/lib/common/maps.c

@@ -66,9 +66,9 @@ draw_map(int bmap, s_char origin, int map_flags, struct nstr_sect *nsp)
     int i;
     /* Note this is not re-entrant anyway, so we keep the buffers
        around */
-    static u_char *bitmap = (u_char *)0;
+    static u_char *bitmap = NULL;
-    static s_char *wmapbuf = (s_char *)0;
+    static s_char *wmapbuf = NULL;
-    static s_char **wmap = (s_char **)0;
+    static s_char **wmap = NULL;
 
     if (!wmapbuf)
 	wmapbuf = malloc((WORLD_Y * MAPWIDTH(1)) * sizeof(s_char));
@@ -79,7 +79,7 @@ draw_map(int bmap, s_char origin, int map_flags, struct nstr_sect *nsp)
 		wmap[i] = &wmapbuf[MAPWIDTH(1) * i];
 	} else if (wmap) {
 	    free(wmap);
-	    wmap = (s_char **)0;
+	    wmap = NULL;
 	}
     }
     if (!bitmap)

src/lib/common/path.c

@@ -88,7 +88,7 @@ bp_init(void)
     if (bp->adp == NULL)
 	return NULL;
 
-    if (neighsects == (struct sctstr **)0)
+    if (neighsects == NULL)
 	neighsects = calloc(((WORLD_X * WORLD_Y) / 2) * 6,
 			    sizeof(struct sctstr *));
 
@@ -201,12 +201,12 @@ bp_neighbors(struct as_coord c, struct as_coord *cp, s_char *pp)
     offset = (sy * WORLD_X + sx) / 2;
     from = &sectp[offset];
 
-    if (neighsects == (struct sctstr **)0)
+    if (neighsects == NULL)
 	ssp = (struct sctstr **)&tsp[0];
     else
 	ssp = (struct sctstr **)&neighsects[offset * 6];
     for (q = 1; q <= 6; q++, ssp++) {
-	if (*ssp == (struct sctstr *)0) {
+	if (*ssp == NULL) {
 	    /* We haven't cached this neighbor yet */
 	    nx = x + diroff[q][0];
 	    ny = y + diroff[q][1];
@@ -360,7 +360,7 @@ BestLandPath(s_char *path,
     *path = 0;
     *cost = 0.0;
     if (best_path(from, to, path, mob_type) < 0)
-	return (s_char *)0;
+	return NULL;
     *cost = pathcost(from, path, mob_type);
     length = strlen(path);
     path[length] = 'h';

src/lib/gen/queue.c

@@ -50,11 +50,11 @@ emp_insque(struct emp_qelem *elem, struct emp_qelem *queue)
 void
 emp_remque(struct emp_qelem *elem)
 {
-    if (elem == (struct emp_qelem *)0)
+    if (!elem)
 	return;
-    if (elem->q_forw != (struct emp_qelem *)0)
+    if (elem->q_forw)
 	elem->q_forw->q_back = elem->q_back;
-    if (elem->q_back != (struct emp_qelem *)0)
+    if (elem->q_back)
 	elem->q_back->q_forw = elem->q_forw;
 }
 

src/lib/subs/attsub.c

@@ -2123,7 +2123,7 @@ take_casualty(int combat_mode, struct combat *off, struct emp_qelem *olist)
      *  Procedure: find the biggest unit remaining (in
      *  terms of mil) and give it the casualties.
      */
-    biggest = (struct emp_qelem *)0;
+    biggest = NULL;
     biggest_mil = -1;
     for (qp = olist->q_forw; qp != olist; qp = qp->q_forw) {
 	llp = (struct llist *)qp;
@@ -2133,7 +2133,7 @@ take_casualty(int combat_mode, struct combat *off, struct emp_qelem *olist)
 	    biggest = qp;
 	}
     }
-    if (biggest == (struct emp_qelem *)0)
+    if (biggest == NULL)
 	return CASUALTY_LUMP - to_take;
 
     llp = (struct llist *)biggest;

src/lib/subs/move.c

@@ -85,9 +85,9 @@ move_ground(s_char *what, struct sctstr *start, struct sctstr *end,
 	pr("Looking for best path to %s\n", path);
 	path = BestLandPath(buf2, start, &ending_sect, &total_mcost,
 			    MOB_ROAD);
-	if (exploring && (path != (s_char *)0))	/* take off the 'h' */
+	if (exploring && path)	/* take off the 'h' */
-	    *(path + strlen(path) - 1) = '\0';
+	    path[strlen(path) - 1] = '\0';
-	if (path == (s_char *)0)
+	if (!path)
 	    pr("No owned path exists!\n");
 	else {
 	    pr("Using best path '%s', movement cost %1.3f\n",
@@ -111,11 +111,11 @@ move_ground(s_char *what, struct sctstr *start, struct sctstr *end,
     for (;;) {
 	oldx = curx;
 	oldy = cury;
-	if (movstr == 0 || *movstr == 0) {
+	if (!movstr || *movstr == 0) {
 	    if (exploring) {
-		map(what, curx, cury, (s_char *)0);
+		map(what, curx, cury, NULL);
 	    } else {
-		move_map(what, curx, cury, (s_char *)0);
+		move_map(what, curx, cury, NULL);
 	    }
 	    sprintf(prompt, "<%.1f: %c %s> ", mobility,
 		    dchr[sect.sct_type].d_mnem,
@@ -128,17 +128,16 @@ move_ground(s_char *what, struct sctstr *start, struct sctstr *end,
 				      MOB_ROAD);
 	    } else {
 		pr("Invalid destination sector!\n");
-		movstr = (s_char *)0;
+		movstr = NULL;
 	    }
 
-	    if (movstr == (s_char *)0) {
+	    if (movstr == NULL) {
 		pr("Can't get to %s from here!\n",
 		   xyas(dx, dy, player->cnum));
-		movstr = (s_char *)0;
 	    } else {
 		if ((mv_cost * weight) > mobility) {
 		    pr("Not enough mobility to go all the way. Nothing moved.\n");
-		    movstr = (s_char *)0;
+		    movstr = NULL;
 		} else {
 		    pr("Using best path '%s', movement cost %1.3f\n",
 		       movstr, mv_cost);
@@ -147,7 +146,7 @@ move_ground(s_char *what, struct sctstr *start, struct sctstr *end,
 		}
 	    }
 	}
-	if (movstr == 0 || *movstr == 0) {
+	if (!movstr || *movstr == 0) {
 	    buf2[0] = dirch[DIR_STOP];
 	    buf2[1] = 0;
 	    movstr = buf2;

src/lib/subs/supply.c

@@ -199,8 +199,7 @@ s_commod(int own, int x, int y, i_type type, int total_wanted,
 	    continue;
 	if (sect.sct_effic < 60)
 	    continue;
-	if (BestLandPath(buf, &dest, &sect, &move_cost, MOB_ROAD) ==
+	if (!BestLandPath(buf, &dest, &sect, &move_cost, MOB_ROAD))
-	    (s_char *)0)
 	    continue;
 	if (!opt_NOFOOD && type == I_FOOD) {
 	    minimum = 2 + ((etu_per_update * eatrate)
@@ -275,8 +274,7 @@ s_commod(int own, int x, int y, i_type type, int total_wanted,
 	    continue;
 	if (sect.sct_effic < 2)
 	    continue;
-	if (BestLandPath(buf, &dest, &sect, &move_cost, MOB_ROAD) ==
+	if (!BestLandPath(buf, &dest, &sect, &move_cost, MOB_ROAD))
-	    (s_char *)0)
 	    continue;
 	if (!opt_NOFOOD && type == I_FOOD)
 	    minimum = 2 + ((etu_per_update * eatrate)
@@ -351,8 +349,7 @@ s_commod(int own, int x, int y, i_type type, int total_wanted,
 	    continue;
 
 	getsect(land.lnd_x, land.lnd_y, &sect);
-	if (BestLandPath(buf, &dest, &sect, &move_cost, MOB_ROAD) ==
+	if (!BestLandPath(buf, &dest, &sect, &move_cost, MOB_ROAD))
-	    (s_char *)0)
 	    continue;
 
 	if ((land.lnd_ship >= 0) && (sect.sct_type != SCT_HARBR))

src/lib/update/distribute.c

@@ -79,7 +79,7 @@ dodistribute(struct sctstr *sp, int imex, s_char *path, double dist_i_cost,
     if ((sp->sct_dist_x == sp->sct_x) && (sp->sct_dist_y == sp->sct_y))
 	return 0;
 
-    if (path == (s_char *)0) {
+    if (!path) {
 	if (sp->sct_own != 0) {
 	    if (imex == EXPORT)	/* only want this once */
 		wu(0, sp->sct_own, "No path to dist sector for %s\n",

src/lib/update/finish.c

@@ -80,12 +80,12 @@ finish_sects(int etu)
     int n;
     struct distinfo *infptr;
 
-    if (g_distptrs == (struct distinfo *)0) {
+    if (g_distptrs == NULL) {
 	logerror("First update since reboot, allocating buffer\n");
 	/* Allocate the information buffer */
 	g_distptrs = (struct distinfo *)(malloc((WORLD_X * WORLD_Y) *
 						sizeof(struct distinfo)));
-	if (g_distptrs == (struct distinfo *)0) {
+	if (g_distptrs == NULL) {
 	    logerror("malloc failed in finish_sects.\n");
 	    return;
 	}
@@ -191,7 +191,7 @@ assemble_dist_paths(struct distinfo *distptrs)
 	infptr = &distptrs[XYOFFSET(sp->sct_x, sp->sct_y)];
 	/* now, get the dist sector */
 	dist = getsectp(sp->sct_dist_x, sp->sct_dist_y);
-	if (dist == (struct sctstr *)0) {
+	if (dist == NULL) {
 	    logerror("Bad dist sect %d,%d for %d,%d !\n", sp->sct_dist_x,
 		     sp->sct_dist_y, sp->sct_x, sp->sct_y);
 	    continue;
@@ -202,13 +202,13 @@ assemble_dist_paths(struct distinfo *distptrs)
 	path = BestDistPath(buf, dist, sp, &d, MOB_ROAD);
 
 	/* Now, we have a path */
-	if (path != (s_char *)0) {
+	if (path != NULL) {
 #ifdef SAVE_FINISH_PATHS
 	    int len;
 	    /* Here we malloc a buffer and save it */
 	    len = strlen(path);
 	    infptr->path = malloc(len);
-	    if (infptr->path == (s_char *)0) {
+	    if (infptr->path == NULL) {
 		logerror("malloc failed in assemble_dist_path!\n");
 		return;
 	    }
@@ -236,12 +236,12 @@ ReversePath(s_char *path)
     static s_char new_path[512];
     int ind;
 
-    if (path == (s_char *)0)
+    if (path == NULL)
-	return (s_char *)0;
+	return NULL;
 
     ind = strlen(path);
     if (ind == 0)
-	return (s_char *)0;
+	return NULL;
 
     if (path[ind - 1] == 'h')
 	ind--;

src/lib/update/main.c

@@ -102,7 +102,7 @@ update_main(void *unused)
     bp = calloc(WORLD_X * WORLD_Y * 7, sizeof(int));
     for (n = 0; n < MAXNOC; n++) {
 	money[n] = 0;
-	if ((np = getnatp(n)) == (struct natstr *)0)
+	if (!(np = getnatp(n)))
 	    continue;
 	money[n] = np->nat_money;
 	tpops[n] = count_pop(n);
@@ -118,7 +118,7 @@ update_main(void *unused)
 
 	memset(p_sect, 0, sizeof(p_sect));
 	mil_dbl_pay = 0;
-	if ((np = getnatp(x)) == (struct natstr *)0)
+	if (!(np = getnatp(x)))
 	    continue;
 	if (np->nat_stat == STAT_SANCT) {
 #ifdef DEBUG

src/lib/update/nxtitemp.c

@@ -63,7 +63,7 @@ nxtitemp(struct nstr_item *np)
 	    np->cur++;
 	}
 	gp = ef_ptr(np->type, np->cur);
-	if (gp == (struct genitem *)0)
+	if (!gp)
 	    return 0;
 
 	selected = 1;

src/lib/update/plane.c

@@ -103,7 +103,7 @@ prod_plane(int etus, int natnum, int *bp, int buildem)
 	}
 
 	onship = 0;
-	shp = (struct shpstr *)0;
+	shp = NULL;
 	if (pp->pln_ship >= 0 && (buildem == 1)) {
 	    if (pp->pln_effic >= 80)
 		continue;