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

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)
-	return (s_char *)0;
+    if (path == NULL)
+	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;