Don't use 0 as null pointer constant, part 3

This part replaces E == 0 by !E, where E has pointer type.

src/lib/commands/acce.c

@@ -49,7 +49,7 @@ acce(void)
     natid cn;
     natid as;
 
-    if (player->argp[1] == 0) {
+    if (!player->argp[1]) {
 	natp = getnatp(player->cnum);
     } else {
 	if (!(natp = natargp(player->argp[1], NULL)))
@@ -64,7 +64,7 @@ acce(void)
     for (cn = 0; cn < MAXNOC; cn++) {
 	if (cn == as)
 	    continue;
-	if ((np = getnatp(cn)) == 0)
+	if (!(np = getnatp(cn)))
 	    break;
 	if (np->nat_stat == STAT_UNUSED)
 	    continue;

src/lib/commands/add.c

@@ -69,7 +69,7 @@ add(void)
     else
 	strcpy(prompt, "New country number? (they all seem to be used) ");
     p = getstarg(player->argp[1], prompt, buf);
-    if (p == 0 || *p == 0)
+    if (!p || !*p)
 	return RET_SYN;
     i = atoi(p);
     if (i >= MAXNOC) {
@@ -83,13 +83,13 @@ add(void)
     }
     natp = getnatp(coun);
     p = getstarg(player->argp[2], "Country Name? ", buf);
-    if (p ==0)
+    if (!p)
 	return RET_SYN;
     if (!check_nat_name(p))
 	return RET_FAIL;
     strcpy(cntryname, p);
     p = getstarg(player->argp[3], "Representative? ", buf);
-    if (p == 0 || *p == 0)
+    if (!p || !*p)
 	return RET_SYN;
     if (strlen(p) >= sizeof(pname)) {
 	pr("Representative too long\n");
@@ -98,7 +98,7 @@ add(void)
     strcpy(pname, p);
     p = getstarg(player->argp[4],
 		 "Status? (visitor, new, active, god, delete) ", buf);
-    if (p == 0 || *p == 0)
+    if (!p || !*p)
 	return RET_SYN;
     switch (*p) {
     case 'v':
@@ -122,7 +122,7 @@ add(void)
     }
     p = getstarg(player->argp[5],
 		 "Check, wipe, or ignore existing sectors (c|w|i) ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     snxtitem_all(&ni, EF_LAND);
     while (nxtitem(&ni, &land)) {

src/lib/commands/army.c

@@ -50,7 +50,7 @@ army(void)
     char buf[1024];
 
     cp = getstarg(player->argp[1], "army? ", buf);
-    if (cp == 0)
+    if (!cp)
 	return RET_SYN;
     c = *cp;
     if (!isalpha(c) && c != '~') {

src/lib/commands/bdes.c

@@ -58,7 +58,7 @@ bdes(void)
 	sprintf(prompt, "%s '%c'  desig? ",
 		xyas(nstr.x, nstr.y, player->cnum),
 		d ? d : ' ');
-	if ((p = getstarg(player->argp[2], prompt, buf)) == 0) {
+	if (!(p = getstarg(player->argp[2], prompt, buf))) {
 	    rc = RET_FAIL;
 	    break;
 	}

src/lib/commands/bomb.c

@@ -108,13 +108,13 @@ bomb(void)
     if (!p || !*p)
 	return RET_SYN;
     mission = *p;
-    if (strchr("ps", mission) == 0)
+    if (!strchr("ps", mission))
 	return RET_SYN;
     if (!get_assembly_point(player->argp[4], &ap_sect, buf))
 	return RET_SYN;
     ax = ap_sect.sct_x;
     ay = ap_sect.sct_y;
-    if (getpath(flightpath, player->argp[5], ax, ay, 0, 0, P_FLYING) == 0
+    if (!getpath(flightpath, player->argp[5], ax, ay, 0, 0, P_FLYING)
 	|| *flightpath == 0)
 	return RET_SYN;
     tx = ax;
@@ -492,7 +492,7 @@ ship_bomb(struct emp_qelem *list, struct sctstr *target)
 		      prplane(&plp->plane), plp->bombs);
 	shipno = -1;
 	while (shipno < 0) {
-	    if ((q = getstring(prompt, buf)) == 0)
+	    if (!(q = getstring(prompt, buf)))
 		goto out;
 	    if (*q == 0)
 		continue;
@@ -615,7 +615,7 @@ plane_bomb(struct emp_qelem *list, struct sctstr *target)
 		      prplane(&plp->plane), plp->bombs);
 	planeno = -1;
 	while (planeno < 0) {
-	    if ((q = getstring(prompt, buf)) == 0)
+	    if (!(q = getstring(prompt, buf)))
 		return;
 	    if (*q == 0)
 		continue;
@@ -721,7 +721,7 @@ land_bomb(struct emp_qelem *list, struct sctstr *target)
 		      prplane(&plp->plane), plp->bombs);
 	unitno = -1;
 	while (unitno < 0) {
-	    if ((q = getstring(prompt, buf)) == 0)
+	    if (!(q = getstring(prompt, buf)))
 		return;
 	    if (*q == 0)
 		continue;

src/lib/commands/buil.c

@@ -89,7 +89,7 @@ buil(void)
     p = getstarg(player->argp[1],
 		 "Build (ship, nuke, bridge, plane, land unit, tower)? ",
 		 buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     what = *p;
 
@@ -103,7 +103,7 @@ buil(void)
     switch (what) {
     case 'p':
 	p = getstarg(player->argp[3], "Plane type? ", buf);
-	if (p == 0 || *p == 0)
+	if (!p || !*p)
 	    return RET_SYN;
 	type = ef_elt_byname(EF_PLANE_CHR, p);
 	if (type >= 0) {
@@ -121,7 +121,7 @@ buil(void)
 	break;
     case 's':
 	p = getstarg(player->argp[3], "Ship type? ", buf);
-	if (p == 0 || *p == 0)
+	if (!p || !*p)
 	    return RET_SYN;
 	type = ef_elt_byname(EF_SHIP_CHR, p);
 	if (type >= 0) {
@@ -141,7 +141,7 @@ buil(void)
 	break;
     case 'l':
 	p = getstarg(player->argp[3], "Land unit type? ", buf);
-	if (p == 0 || *p == 0)
+	if (!p || !*p)
 	    return RET_SYN;
 	type = ef_elt_byname(EF_LAND_CHR, p);
 	if (type >= 0) {
@@ -182,7 +182,7 @@ buil(void)
 	    return RET_FAIL;
 	}
 	p = getstarg(player->argp[3], "Nuke type? ", buf);
-	if (p == 0 || *p == 0)
+	if (!p || !*p)
 	    return RET_SYN;
 	type = ef_elt_byname(EF_NUKE_CHR, p);
 	if (type >= 0) {
@@ -219,7 +219,7 @@ buil(void)
 			"Are you sure that you want to build %s of them? ",
 			player->argp[4]);
 		p = getstarg(player->argp[6], bstr, buf);
-		if (p == 0 || *p != 'y')
+		if (!p || *p != 'y')
 		    return RET_SYN;
 	    }
 	}

src/lib/commands/buy.c

@@ -81,7 +81,7 @@ buy(void)
     display_mark(ip->i_uid, 0);
     pr("\n");
     p = getstarg(player->argp[2], "Which lot are you bidding on: ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     if (*p == 0)
 	return RET_SYN;
@@ -100,7 +100,7 @@ buy(void)
 	pr("You can't bid on your own lot.\n");
 	return RET_OK;
     }
-    if ((p = getstarg(player->argp[3], "How much per unit: ", buf)) == 0)
+    if (!(p = getstarg(player->argp[3], "How much per unit: ", buf)))
 	return RET_SYN;
     bid = atof(p);
     if (bid <= 0)

src/lib/commands/cede.c

@@ -78,7 +78,7 @@ cede(void)
 
 	p = getstarg(player->argp[3], "Cede sectors or ships (se, sh)? ",
 		     buf);
-	if (p == 0)
+	if (!p)
 	    return RET_FAIL;
 	if (strlen(p) > 4)
 	    p[2] = 0;

src/lib/commands/chan.c

@@ -47,7 +47,7 @@ chan(void)
     struct natstr *us;
 
     p = getstarg(player->argp[1], "country name or representative? ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     us = getnatp(player->cnum);
     if (us->nat_stat == STAT_VIS) {
@@ -76,7 +76,7 @@ chan(void)
 	    }
 	}
 	p = getstarg(player->argp[2], "New country name -- ", buf);
-	if (p == 0)
+	if (!p)
 	    return RET_SYN;
 	if (!check_nat_name(p))
 	    return RET_FAIL;
@@ -90,7 +90,7 @@ chan(void)
     case 'r':
 	pr("(note: these are stored in plain text.)\n");
 	p = getstarg(player->argp[2], "New representative name -- ", buf);
-	if (p == 0)
+	if (!p)
 	    return RET_SYN;
 	p[sizeof(us->nat_pnam) - 1] = 0;
 	strcpy(us->nat_pnam, p);

src/lib/commands/coas.c

@@ -119,7 +119,7 @@ coas(void)
 		    continue;
 		y = ynorm(sect.sct_y + k);
 		n = scthash(x, y, TSIZE);
-		if (list[n] == 0)
+		if (!list[n])
 		    continue;
 		nship -= showship(&list[n], x, y);
 	    }

src/lib/commands/cons.c

@@ -114,7 +114,7 @@ cons_choose(struct ltcomstr *ltcp)
     char buf[1024];
 
     memset(ltcp, 0, sizeof(*ltcp));
-    if (getstarg(player->argp[1], "loan or treaty? ", buf) == 0)
+    if (!getstarg(player->argp[1], "loan or treaty? ", buf))
 	return RET_SYN;
     ltcp->type = ef_byname_from(buf, lon_or_trt);
     switch (ltcp->type) {

src/lib/commands/deli.c

@@ -50,7 +50,7 @@ deli(void)
     char prompt[128];
     char *p;
 
-    if ((ich = whatitem(player->argp[1], "deliver what? ")) == 0)
+    if (!(ich = whatitem(player->argp[1], "deliver what? ")))
 	return RET_SYN;
     if (!snxtsct(&nstr, player->argp[2]))
 	return RET_SYN;

src/lib/commands/desi.c

@@ -64,7 +64,7 @@ desi(void)
 	sprintf(prompt, "%s %d%% %s  desig? ",
 		xyas(sect.sct_x, sect.sct_y, player->cnum),
 		sect.sct_effic, dchr[sect.sct_type].d_name);
-	if ((p = getstarg(player->argp[2], prompt, buf)) == 0) {
+	if (!(p = getstarg(player->argp[2], prompt, buf))) {
 	    rc = RET_FAIL;
 	    break;
 	}

src/lib/commands/drop.c

@@ -64,14 +64,14 @@ drop(void)
 	return RET_SYN;
     ax = ap_sect.sct_x;
     ay = ap_sect.sct_y;
-    if (getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING) == 0
+    if (!getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING)
 	|| *flightpath == 0)
 	return RET_SYN;
     tx = ax;
     ty = ay;
     (void)pathtoxy(flightpath, &tx, &ty, fcost);
     pr("target is %s\n", xyas(tx, ty, player->cnum));
-    if ((ip = whatitem(player->argp[5], "Drop off what? ")) == 0)
+    if (!(ip = whatitem(player->argp[5], "Drop off what? ")))
 	return RET_SYN;
     getsect(tx, ty, &target);
 

src/lib/commands/edit.c

@@ -88,7 +88,7 @@ edit(void)
     what = getstarg(player->argp[1],
 		    "Edit What (country, land, ship, plane, nuke, unit)? ",
 		    buf);
-    if (what == 0)
+    if (!what)
 	return RET_SYN;
     ewhat = what[0];
     switch (ewhat) {
@@ -130,7 +130,7 @@ edit(void)
 	pr("huh?\n");
 	return RET_SYN;
     }
-    if (player->argp[3] == 0) {
+    if (!player->argp[3]) {
 	switch (ewhat) {
 	case 'l':
 	    prsect(&sect);
@@ -374,7 +374,7 @@ pr_ship(struct shpstr *ship)
 {
     struct natstr *natp;
 
-    if ((natp = getnatp(ship->shp_own)) == 0)
+    if (!(natp = getnatp(ship->shp_own)))
 	return;
     pr("%s (#%d) %s\n", natp->nat_cnam, ship->shp_own, prship(ship));
     pr("UID <U>: %d\n", ship->shp_uid);

src/lib/commands/enli.c

@@ -60,7 +60,7 @@ enli(void)
     natp = getnatp(player->cnum);
     newmil = 500;
     sprintf(prompt, "Number to enlist (max %d) : ", newmil);
-    if ((p = getstarg(player->argp[2], prompt, buf)) == 0)
+    if (!(p = getstarg(player->argp[2], prompt, buf)))
 	return RET_SYN;
     if ((milwant = atoi(p)) > newmil)
 	milwant = newmil;

src/lib/commands/expl.c

@@ -75,7 +75,7 @@ explore(void)
 	pr("You can only explore with civs and mil.\n");
 	return RET_FAIL;
     }
-    if ((p = getstarg(player->argp[2], "from sector : ", buf)) == 0)
+    if (!(p = getstarg(player->argp[2], "from sector : ", buf)))
 	return RET_SYN;
     if (!sarg_xy(p, &x, &y))
 	return RET_SYN;

src/lib/commands/flee.c

@@ -50,7 +50,7 @@ flee(void)
     char buf[1024];
 
     cp = getstarg(player->argp[1], "fleet? ", buf);
-    if (cp == 0)
+    if (!cp)
 	return RET_SYN;
     c = *cp;
     if (!isalpha(c) && c != '~') {

src/lib/commands/fly.c

@@ -66,7 +66,7 @@ fly(void)
 	return RET_SYN;
     ax = ap_sect.sct_x;
     ay = ap_sect.sct_y;
-    if (getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING) == 0
+    if (!getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING)
 	|| *flightpath == 0)
 	return RET_SYN;
     tx = ax;

src/lib/commands/foll.c

@@ -54,7 +54,7 @@ foll(void)
     if (!snxtitem(&nstr, EF_SHIP, player->argp[1], NULL))
 	return RET_SYN;
     cp = getstarg(player->argp[2], "leader? ", buf);
-    if (cp == 0)
+    if (!cp)
 	cp = "";
     good = sscanf(cp, "%d", &leader);
     if (!good)

src/lib/commands/fort.c

@@ -50,7 +50,7 @@ fort(void)
     if (!snxtitem(&ni, EF_LAND, player->argp[1], NULL))
 	return RET_SYN;
     p = getstarg(player->argp[2], "Amount: ", buf);
-    if (p == 0 || *p == 0)
+    if (!p || !*p)
 	return RET_SYN;
     fort_amt = atoi(p);
     if (fort_amt > land_mob_max)

src/lib/commands/give.c

@@ -59,7 +59,7 @@ give(void)
 	return RET_SYN;
     while (nxtsct(&nstr, &sect) > 0) {
 	p = getstarg(player->argp[3], "how much : ", buf);
-	if (p == 0 || *p == '\0')
+	if (!p || !*p)
 	    return RET_SYN;
 	if ((amt = atoi(p)) == 0)
 	    return RET_SYN;

src/lib/commands/grin.c

@@ -56,7 +56,7 @@ grin(void)
     }
     pp = &pchr[prd];
 
-    if ((p = getstarg(player->argp[1], "Sectors? ", buf)) == 0)
+    if (!(p = getstarg(player->argp[1], "Sectors? ", buf)))
 	return RET_SYN;
     if (!snxtsct(&nstr, p))
 	return RET_SYN;

src/lib/commands/info.c

@@ -94,7 +94,7 @@ info(void)
     if (fp == NULL) {
 	/* may be a "partial" request.  */
 	info_dp = opendir(infodir);
-	if (info_dp == 0) {
+	if (!info_dp) {
 	    pr("Can't open info dir\n");
 	    logerror("Can't open info dir \"%s\"\n", infodir);
 	    return RET_FAIL;
@@ -174,7 +174,7 @@ apro(void)
     int lhitlim;
     struct stat statb;
 
-    if (player->argp[1] == 0 || !*player->argp[1]) {
+    if (!player->argp[1] || !*player->argp[1]) {
 	pr("Apropos what?\n");
 	return RET_FAIL;
     }

src/lib/commands/laun.c

@@ -363,7 +363,7 @@ launch_sat(struct plnstr *pp, int sublaunch)
 	return RET_FAIL;
     }
     p = getstring("Geostationary orbit? ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     if (!check_plane_ok(pp))
 	return RET_FAIL;

src/lib/commands/miss.c

@@ -64,7 +64,7 @@ mission(void)
 
     p = getstarg(player->argp[1], "Ship, plane or land unit (p,sh,la)? ",
 		 buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     type = ef_byname_from(p, ef_with_missions);
     if (type < 0) {
@@ -77,7 +77,7 @@ mission(void)
     p = getstarg(player->argp[3],
 		 "Mission (int, sup, osup, dsup, esc, res, air, query, clear)? ",
 		 buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
 
 /*

src/lib/commands/move.c

@@ -72,7 +72,7 @@ move(void)
 
 
     istest = *player->argp[0] == 't';
-    if ((ip = whatitem(player->argp[1], "move what? ")) == 0)
+    if (!(ip = whatitem(player->argp[1], "move what? ")))
 	return RET_SYN;
     vtype = ip->i_uid;
     if (!(p = getstarg(player->argp[2], "from sector : ", buf)))

src/lib/commands/name.c

@@ -57,7 +57,7 @@ name(void)
 	p = getstarg(player->argp[2], "Name? ", buf);
 	if (!check_ship_ok(&ship))
 	    return RET_FAIL;
-	if (p == 0 || *p == 0)
+	if (!p || !*p)
 	    return RET_SYN;
 	if (!strcmp(p, "~")) {
 	    ship.shp_name[0] = 0;

src/lib/commands/new.c

@@ -66,7 +66,7 @@ new(void)
 	pr("Country #%d (%s) isn't a new country!\n", num, cname(num));
 	return RET_SYN;
     }
-    if ((p = getstarg(player->argp[2], "sanctuary pair : ", buf)) == 0)
+    if (!(p = getstarg(player->argp[2], "sanctuary pair : ", buf)))
 	return RET_SYN;
     if (!sarg_xy(p, &x, &y) || !getsect(x, y, &sect))
 	return RET_SYN;

src/lib/commands/offe.c

@@ -102,7 +102,7 @@ do_treaty(void)
     theircond = 0;
     for (tfp = treaty_flags; tfp && tfp->name; tfp++) {
 	sprintf(prompt, "%s? ", tfp->name);
-	if ((cp = getstring(prompt, buf)) == 0)
+	if (!(cp = getstring(prompt, buf)))
 	    return RET_FAIL;
 	if (*cp == 'y')
 	    theircond |= tfp->value;
@@ -111,7 +111,7 @@ do_treaty(void)
     ourcond = 0;
     for (tfp = treaty_flags; tfp && tfp->name; tfp++) {
 	sprintf(prompt, "%s? ", tfp->name);
-	if ((cp = getstring(prompt, buf)) == 0)
+	if (!(cp = getstring(prompt, buf)))
 	    return RET_FAIL;
 	if (*cp == 'y')
 	    ourcond |= tfp->value;
@@ -121,7 +121,7 @@ do_treaty(void)
 	return RET_SYN;
     }
     cp = getstring("Proposed treaty duration? (days) ", buf);
-    if (cp == 0)
+    if (!cp)
 	return RET_FAIL;
     j = atoi(cp);
     if (j <= 0) {

src/lib/commands/orde.c

@@ -184,7 +184,7 @@ orde(void)
 		sub = atoi(player->argp[3]);
 	    else {
 		sprintf(buf1, "Field (1-%d) ", TMAX);
-		if (getstarg(player->argp[3], buf1, buf) == 0)
+		if (!getstarg(player->argp[3], buf1, buf))
 		    return RET_SYN;
 		sub = atoi(buf);
 	    }

src/lib/commands/para.c

@@ -68,7 +68,7 @@ para(void)
 	return RET_SYN;
     ax = ap_sect.sct_x;
     ay = ap_sect.sct_y;
-    if (getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING) == 0
+    if (!getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING)
 	|| *flightpath == 0)
 	return RET_SYN;
     tx = ax;

src/lib/commands/rada.c

@@ -67,7 +67,7 @@ radar(short type)
     sprintf(prompt, "Radar from (%s # or sector(s)) : ", ef_nameof(type));
     cp = getstarg(player->argp[1], prompt, buf);
 
-    if (cp == 0)
+    if (!cp)
 	return RET_SYN;
     switch (sarg_type(cp)) {
     case NS_AREA:

src/lib/commands/rea.c

@@ -103,7 +103,7 @@ rea(void)
 	clear_telegram_is_new(player->cnum);
     }
 
-    if ((telfp = fopen(mbox, "rb+")) == 0) {
+    if (!(telfp = fopen(mbox, "rb+"))) {
 	logerror("telegram file %s", mbox);
 	return RET_FAIL;
     }

src/lib/commands/real.c

@@ -72,7 +72,7 @@ real(void)
 	    return RET_SYN;
 	}
     }
-    if (player->argp[2] == 0) {
+    if (!player->argp[2]) {
 	while (curr <= lastr) {
 	    list_realm(curr, natp);
 	    curr++;

src/lib/commands/reco.c

@@ -62,7 +62,7 @@ reco(void)
 	return RET_SYN;
     ax = ap_sect.sct_x;
     ay = ap_sect.sct_y;
-    if (getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING) == 0
+    if (!getpath(flightpath, player->argp[4], ax, ay, 0, 0, P_FLYING)
 	|| *flightpath == 0)
 	return RET_SYN;
     tx = ax;

src/lib/commands/reje.c

@@ -46,7 +46,7 @@ reje(void)
     struct nstr_item ni;
     char buf[1024];
 
-    if ((p = getstarg(player->argp[1], "reject or accept? ", buf)) == 0)
+    if (!(p = getstarg(player->argp[1], "reject or accept? ", buf)))
 	return RET_SYN;
     switch (*p) {
     case 'r':
@@ -61,7 +61,7 @@ reje(void)
     }
     p = getstarg(player->argp[2],
 		 "mail, treaties, loans, or announcements? ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     switch (*p) {
     case 'a':

src/lib/commands/rela.c

@@ -50,7 +50,7 @@ rela(void)
     natid as;
     int n;
 
-    if (player->argp[1] == 0)
+    if (!player->argp[1])
 	as = player->cnum;
     else {
 	if ((n = natarg(player->argp[1], NULL)) < 0)
@@ -63,7 +63,7 @@ rela(void)
     pr("\n  Formal Relations         %5s      theirs\n",
        player->cnum == as ? "yours" : "his");
     for (cn = 1; cn < MAXNOC; cn++) {
-	if ((np = getnatp(cn)) == 0)
+	if (!(np = getnatp(cn)))
 	    break;
 	if (cn == as)
 	    continue;

src/lib/commands/repa.c

@@ -58,7 +58,7 @@ repa(void)
     }
     natp = getnatp(player->cnum);
     cp = getstarg(player->argp[1], "Repay loan #? ", buf);
-    if (cp == 0)
+    if (!cp)
 	return RET_SYN;
     loan_num = atoi(cp);
     if (loan_num < 0)
@@ -68,7 +68,7 @@ repa(void)
 	pr("You don't owe anything on that loan.\n");
 	return RET_FAIL;
     }
-    if ((cp = getstarg(player->argp[2], "amount? ", buf)) == 0)
+    if (!(cp = getstarg(player->argp[2], "amount? ", buf)))
 	return RET_SYN;
     if (!check_loan_ok(&loan))
 	return RET_FAIL;

src/lib/commands/rese.c

@@ -87,7 +87,7 @@ rese(void)
 	    return RET_OK;
 	}
 	if (player->god) {
-	    if ((p = getstring("Really destroy that lot? ", buf)) == 0)
+	    if (!(p = getstring("Really destroy that lot? ", buf)))
 		return RET_FAIL;
 	    if (!check_comm_ok(&comm))
 		return RET_FAIL;

src/lib/commands/rout.c

@@ -61,7 +61,7 @@ rout(void)
     static char **map = NULL;
     int i;
 
-    if ((ip = whatitem(player->argp[1], "What item? ")) == 0)
+    if (!(ip = whatitem(player->argp[1], "What item? ")))
 	return RET_SYN;
     i_del = ip->i_uid;;
     if (!snxtsct(&ns, player->argp[2]))

src/lib/commands/scra.c

@@ -73,7 +73,7 @@ scra(void)
 	return RET_SYN;
     }
     sprintf(prompt, "%s(s)? ", ef_nameof(type));
-    if ((p = getstarg(player->argp[2], prompt, buf)) == 0)
+    if (!(p = getstarg(player->argp[2], prompt, buf)))
 	return RET_SYN;
     if (!snxtitem(&ni, type, p, NULL))
 	return RET_SYN;

src/lib/commands/scut.c

@@ -68,7 +68,7 @@ scut(void)
 	return RET_SYN;
     }
     sprintf(prompt, "%s(s)? ", ef_nameof(type));
-    if ((p = getstarg(player->argp[2], prompt, buf)) == 0)
+    if (!(p = getstarg(player->argp[2], prompt, buf)))
 	return RET_SYN;
     if (!snxtitem(&ni, type, p, NULL))
 	return RET_SYN;

src/lib/commands/set.c

@@ -73,7 +73,7 @@ set(void)
     check_trade();
 
     p = getstarg(player->argp[1], "Ship, plane, land unit or nuke? ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     if ((type = ef_byname_from(p, ef_saleable)) < 0) {
 	pr("You can sell only ships, planes, land units or nukes\n");
@@ -92,7 +92,7 @@ set(void)
 	trade.trd_type = type;
 	sprintf(prompt, "%s #%d; Price? ",
 		trade_nameof(&trade, &item), ni.cur);
-	if ((p = getstarg(player->argp[3], prompt, buf)) == 0)
+	if (!(p = getstarg(player->argp[3], prompt, buf)))
 	    return RET_FAIL;
 	if (!trade_check_item_ok(&item))
 	    return RET_FAIL;

src/lib/commands/setres.c

@@ -53,7 +53,7 @@ setres(void)
     what = getstarg(player->argp[1],
 		    "Set What (iron, gold, oil, uranium, fertility)? ",
 		    buf);
-    if (what == 0)
+    if (!what)
 	return RET_SYN;
     switch (what[0]) {
     case 'i':

src/lib/commands/setsect.c

@@ -57,7 +57,7 @@ setsector(void)
     what = getstarg(player->argp[1],
 		    "Give What (iron, gold, oil, uranium, fertility, owner, eff., mob., work, avail., oldown, mines)? ",
 		    buf);
-    if (what == 0)
+    if (!what)
 	return RET_SYN;
     char0 = what[0];
     char1 = what[1];

src/lib/commands/shark.c

@@ -57,7 +57,7 @@ shark(void)
 	return RET_FAIL;
     }
     p = getstarg(player->argp[1], "Transfer which loan #: ", buf);
-    if (p == 0)
+    if (!p)
 	return RET_SYN;
     if (*p == 0)
 	return RET_SYN;

src/lib/commands/shoo.c

@@ -57,14 +57,14 @@ shoo(void)
     char buf[1024];
 
     ip = whatitem(player->argp[1], "Shoot what <civ or uw> ");
-    if (ip == 0 || (ip->i_uid != I_CIVIL && ip->i_uid != I_UW))
+    if (!ip || (ip->i_uid != I_CIVIL && ip->i_uid != I_UW))
 	return RET_SYN;
     item = ip->i_uid;
     if (!snxtsct(&nstr, player->argp[2]))
 	return RET_SYN;
     sprintf(prompt, "number of %s to shoot? ", ip->i_name);
     p = getstarg(player->argp[3], prompt, buf);
-    if (p == 0 || (targets = atoi(p)) <= 0)
+    if (!p || (targets = atoi(p)) <= 0)
 	return RET_SYN;
     while (nxtsct(&nstr, &sect)) {
 	if (!player->owner)

src/lib/commands/skyw.c

@@ -111,7 +111,7 @@ skyw(void)
 		    continue;
 		y = ynorm(sect.sct_y + k);
 		n = scthash(x, y, TSIZE);
-		if (list[n] == 0)
+		if (!list[n])
 		    continue;
 		nsat -= showsat(&list[n], x, y);
 	    }

src/lib/commands/stop.c

@@ -76,7 +76,7 @@ start_stop(int off)
     } else {
 	p = getstarg(player->argp[1],
 		     "Sector, ship, plane, land unit or nuke? ", buf);
-	if (p == 0)
+	if (!p)
 	    return RET_SYN;
 	type = ef_byname_from(p, sct_or_unit);
 	if (type < 0) {

src/lib/commands/terr.c

@@ -59,7 +59,7 @@ 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(player->argp[2], prompt, buf)) == 0)
+	if (!(p = getstarg(player->argp[2], prompt, buf)))
 	    return RET_FAIL;
 	if (*p == 0)
 	    continue;

src/lib/commands/thre.c

@@ -53,7 +53,7 @@ thre(void)
     char prompt[128];
     char buf[128];
 
-    if ((ip = whatitem(player->argp[1], "What commodity? ")) == 0)
+    if (!(ip = whatitem(player->argp[1], "What commodity? ")))
 	return RET_SYN;
     if (!snxtsct(&nstr, player->argp[2]))
 	return RET_SYN;
@@ -70,7 +70,7 @@ thre(void)
 	    sprintf(prompt, "%s %s  threshold? ",
 		    xyas(nstr.x, nstr.y, player->cnum),
 		    dchr[sect.sct_type].d_name);
-	if ((p = getstarg(player->argp[3], prompt, buf)) == 0)
+	if (!(p = getstarg(player->argp[3], prompt, buf)))
 	    return RET_FAIL;
 	if (!*p)
 	    continue;

src/lib/commands/torp.c

@@ -115,7 +115,7 @@ torp(void)
 	}
 	subno = sub.shp_uid;
 	sprintf(prompt, "Ship %d, target? ", sub.shp_uid);
-	if ((ptr = getstarg(player->argp[2], prompt, buf)) == 0)
+	if (!(ptr = getstarg(player->argp[2], prompt, buf)))
 	    return RET_SYN;
 	if (!check_ship_ok(&sub))
 	    return RET_FAIL;

src/lib/commands/trad.c

@@ -188,7 +188,7 @@ trad(void)
 	    p = getstring("Destination sector: ", buf);
 	    if (!trade_check_ok(&trade, &tg))
 		return RET_FAIL;
-	    if (p == 0) {
+	    if (!p) {
 		return RET_FAIL;
 	    }
 	    if (!sarg_xy(p, &sx, &sy) || !getsect(sx, sy, &sect)) {
@@ -217,7 +217,7 @@ trad(void)
 	    p = getstring("Destination sector: ", buf);
 	    if (!trade_check_ok(&trade, &tg))
 		return RET_FAIL;
-	    if (p == 0) {
+	    if (!p) {
 		return RET_FAIL;
 	    }
 	    if (!sarg_xy(p, &sx, &sy) || !getsect(sx, sy, &sect)) {

src/lib/commands/tran.c

@@ -53,7 +53,7 @@ tran(void)
 
     what = getstarg(player->argp[1], "transport what (nuke or plane): ",
 		    buf);
-    if (what == 0)
+    if (!what)
 	return RET_SYN;
     if (*what == 'n')
 	return tran_nuke();

src/lib/commands/work.c

@@ -55,7 +55,7 @@ work(void)
     if (!snxtitem(&ni, EF_LAND, player->argp[1], NULL))
 	return RET_SYN;
     p = getstarg(player->argp[2], "Amount: ", buf);
-    if (p == 0 || *p == 0)
+    if (!p || !*p)
 	return RET_SYN;
     work_amt = atoi(p);
     if ((work_amt < 0) || (work_amt > land_mob_max)) {

src/lib/common/cnumb.c

@@ -54,7 +54,7 @@ cnumb(char *cntry)
 
     res = M_NOTFOUND;
     for (cn = 0; cn < MAXNOC; cn++) {
-	if ((natp = getnatp(cn)) == 0)
+	if (!(natp = getnatp(cn)))
 	    break;
 	if (natp->nat_stat == STAT_UNUSED)
 	    continue;

src/lib/common/emp_config.c

@@ -153,7 +153,7 @@ keylookup(char *command, struct keymatch *tbl)
 {
     struct keymatch *kp;
 
-    if (command == 0 || *command == 0)
+    if (!command || !*command)
 	return NULL;
     for (kp = tbl; kp->km_key; kp++) {
 	if (strcmp(kp->km_key, command) == 0)

src/lib/common/nat.c

@@ -49,7 +49,7 @@ cname(natid n)
 {
     struct natstr *np;
 
-    if ((np = getnatp(n)) == 0)
+    if (!(np = getnatp(n)))
 	return NULL;
     return np->nat_cnam;
 }

src/lib/common/path.c

@@ -100,7 +100,7 @@ best_path(struct sctstr *from, struct sctstr *to, char *path,
     struct as_data *adp;
     struct as_path *ap;
 
-    if (mybestpath == 0)
+    if (!mybestpath)
 	mybestpath = bp_init();
     adp = mybestpath->adp;
     ap = as_find_cachepath(from->sct_x, from->sct_y, to->sct_x, to->sct_y);

src/lib/lwp/lwp.c

@@ -103,7 +103,7 @@ lwpReschedule(void)
 	if (nextp)
 	    break;
     }
-    if (CANT_HAPPEN(LwpCurrent == 0 && nextp == 0))
+    if (CANT_HAPPEN(!LwpCurrent && !nextp))
 	abort();
     if (LwpCurrent != nextp) {
 	struct lwpProc *oldp = LwpCurrent;

src/lib/lwp/sel.c

@@ -99,7 +99,7 @@ lwpSleepFd(int fd, int mask, struct timeval *timeout)
 	FD_SET(fd, &LwpWritefds);
     LwpNfds++;
 
-    if (LwpMaxfd == 0 && LwpDelayq.head == 0) {
+    if (LwpMaxfd == 0 && !LwpDelayq.head) {
 	/* select process is sleeping until first waiter arrives */
 	lwpStatus(LwpCurrent, "going to resched fd %d", fd);
 	lwpReady(LwpSelProc);
@@ -194,7 +194,7 @@ lwpSleepUntil(time_t until)
     lwpStatus(LwpCurrent, "sleeping for %ld sec",
 	      (long)(until - time(NULL)));
     LwpCurrent->runtime = until;
-    if (LwpMaxfd == 0 && LwpDelayq.head == 0) {
+    if (LwpMaxfd == 0 && !LwpDelayq.head) {
 	/* select process is sleeping until first waiter arrives */
 	lwpReady(LwpSelProc);
     }
@@ -264,7 +264,7 @@ lwpSelect(void *arg)
 	if (n > 0) {
 	    /* file descriptor activity */
 	    for (fd = 0; fd <= LwpMaxfd; fd++) {
-		if (LwpFdwait[fd] == 0)
+		if (!LwpFdwait[fd])
 		    continue;
 		if (FD_ISSET(fd, &readmask)) {
 		    lwpStatus(LwpFdwait[fd], "input ready");

src/lib/player/accept.c

@@ -117,7 +117,7 @@ player_delete(struct player *lp)
 struct player *
 player_next(struct player *lp)
 {
-    if (lp == 0)
+    if (!lp)
 	lp = (struct player *)Players.q_forw;
     else
 	lp = (struct player *)lp->queue.q_forw;
@@ -129,7 +129,7 @@ player_next(struct player *lp)
 struct player *
 player_prev(struct player *lp)
 {
-    if (lp == 0)
+    if (!lp)
 	lp = (struct player *)Players.q_back;
     else
 	lp = (struct player *)lp->queue.q_back;

src/lib/player/dispatch.c

@@ -81,7 +81,7 @@ dispatch(char *buf, char *redir)
 	    return 0;
 	}
     }
-    if (command->c_addr == 0) {
+    if (!command->c_addr) {
 	pr("Command not implemented\n");
 	return 0;
     }

src/lib/subs/askyn.c

@@ -45,7 +45,7 @@ confirm(char *promptstring)
     char y_or_n[1024];
     char c;
 
-    if (getstring(promptstring, y_or_n) == 0)
+    if (!getstring(promptstring, y_or_n))
 	return 0;
     c = *y_or_n;
     if (c == 'y' || c == 'Y')

src/lib/subs/getstarg.c

@@ -46,8 +46,8 @@ char *
 getstarg(char *input, char *prompt, char *buf)
 {
     *buf = '\0';
-    if (input == 0 || *input == 0) {
+    if (!input || !*input) {
-	if (getstring(prompt, buf) == 0)
+	if (!getstring(prompt, buf))
 	    return NULL;
     } else {
 	strcpy(buf, input);

src/lib/subs/mission.c

@@ -913,7 +913,7 @@ mission_pln_equip(struct plist *plp, struct ichrstr *ip, int flags,
 	    break;
 	case 't':		/* transport */
 	case 'd':		/* drop */
-	    if ((pcp->pl_flags & P_C) == 0 || ip == 0)
+	    if (!(pcp->pl_flags & P_C) || !ip)
 		break;
 	    itype = ip->i_uid;
 	    needed = (load * 2) / ip->i_lbs;

src/lib/subs/mtch.c

@@ -49,7 +49,7 @@ comtch(char *command, struct cmndstr *coms, int comstat)
     struct cmndstr *com;
     int status;
 
-    if (command == 0 || *command == 0)
+    if (!command || !*command)
 	return M_IGNORE;
     status = M_NOTFOUND;
     for (com = coms; com->c_form; com++) {

src/lib/subs/natarg.c

@@ -59,7 +59,7 @@ natargp(char *arg, char *prompt)
     struct natstr *np;
 
     arg = getstarg(arg, prompt, buf);
-    if (arg == 0 || *arg == 0)
+    if (!arg || !*arg)
 	return NULL;
     if (isdigit(*arg))
 	n = atoi(arg);

src/lib/subs/nreport.c

@@ -77,7 +77,7 @@ nreport(natid actor, int event, natid victim, int times)
 	return;
     if (!chance((double)-nice * times / 20.0))
 	return;
-    if ((natp = getnatp(victim)) == 0)
+    if (!(natp = getnatp(victim)))
 	return;
     if (getrel(natp, actor) < HOSTILE)
 	return;

src/lib/subs/onearg.c

@@ -41,8 +41,8 @@ onearg(char *arg, char *prompt)
     int n;
     char buf[1024];
 
-    if (arg == 0 || *arg == 0) {
+    if (!arg || !*arg) {
-	if ((arg = getstring(prompt, buf)) == 0)
+	if (!(arg = getstring(prompt, buf)))
 	    return -1;
     }
     n = atoi(arg);

src/lib/subs/plnsub.c

@@ -270,7 +270,7 @@ pln_dropoff(struct emp_qelem *list, struct ichrstr *ip, coord tx, coord ty,
     int there;
     int max;
 
-    if (ip == 0)
+    if (!ip)
 	return;
     amt = 0;
     for (qp = list->q_forw; qp != list; qp = qp->q_forw) {
@@ -664,7 +664,7 @@ pln_equip(struct plist *plp, struct ichrstr *ip, int flags, char mission)
 	    break;
 	case 't':		/* transport */
 	case 'd':		/* drop */
-	    if ((pcp->pl_flags & P_C) == 0 || ip == 0)
+	    if (!(pcp->pl_flags & P_C) || !ip)
 		break;
 	    itype = ip->i_uid;
 	    needed = (load * 2) / ip->i_lbs;

src/lib/subs/rej.c

@@ -149,7 +149,7 @@ setcont(natid us, natid them, int contact)
 {
     struct natstr *np;
 
-    if ((np = getnatp(us)) == 0)
+    if (!(np = getnatp(us)))
 	return 0;
     putcontact(np, them, contact);
     putnat(np);
@@ -161,7 +161,7 @@ setrej(natid us, natid them, int how, int what)
 {
     struct natstr *np;
 
-    if ((np = getnatp(us)) == 0)
+    if (!(np = getnatp(us)))
 	return 0;
     putreject(np, them, how, what);
     putnat(np);

src/lib/subs/snxtitem.c

@@ -66,13 +66,13 @@ snxtitem(struct nstr_item *np, int type, char *str, char *prompt)
 
     np->type = EF_BAD;
     np->sel = NS_UNDEF;
-    if (str == 0) {
+    if (!str) {
 	if (!prompt) {
 	    sprintf(promptbuf, "%s(s)? ", ef_nameof(type));
 	    prompt = promptbuf;
 	}
 	str = getstring(prompt, buf);
-	if (str == 0)
+	if (!str)
 	    return 0;
     }
     if (*str == 0) {
@@ -126,7 +126,7 @@ snxtitem(struct nstr_item *np, int type, char *str, char *prompt)
     default:
 	return 0;
     }
-    if (player->condarg == 0)
+    if (!player->condarg)
 	return 1;
     n = nstr_comp(np->cond, sizeof(np->cond) / sizeof(*np->cond), type,
 		  player->condarg);

src/lib/subs/snxtsct.c

@@ -61,8 +61,8 @@ snxtsct(struct nstr_sect *np, char *str)
     int dist, n;
     char buf[1024];
 
-    if (str == 0 || *str == 0) {
+    if (!str || !*str) {
-	if ((str = getstring("(sects)? ", buf)) == 0)
+	if (!(str = getstring("(sects)? ", buf)))
 	    return 0;
     }
     switch (sarg_type(str)) {
@@ -92,7 +92,7 @@ snxtsct(struct nstr_sect *np, char *str)
     default:
 	return 0;
     }
-    if (player->condarg == 0)
+    if (!player->condarg)
 	return 1;
     n = nstr_comp(np->cond, sizeof(np->cond) / sizeof(*np->cond),
 		  EF_SECTOR, player->condarg);

src/lib/subs/whatitem.c

@@ -48,7 +48,7 @@ whatitem(char *input, char *prompt)
     char buf[1024];
 
     p = getstarg(input, prompt, buf);
-    if (p == 0 || *p == 0)
+    if (!p || !*p)
 	return NULL;
     ip = item_by_name(p);
     if (!ip)

src/lib/subs/wu.c

@@ -131,7 +131,7 @@ typed_wu(natid from, natid to, char *message, int type)
 	mailbox(box, to);
 
     if (type != TEL_ANNOUNCE)
-	if ((np = getnatp(to)) == 0 || np->nat_stat < STAT_SANCT)
+	if (!(np = getnatp(to)) || np->nat_stat < STAT_SANCT)
 	    return -1;
 #if !defined(_WIN32)
     if ((fd = open(box, O_WRONLY | O_APPEND, 0)) < 0) {

src/lib/update/main.c

@@ -137,7 +137,7 @@ update_main(void)
 	/* Update war declarations */
 	/* MOBILIZATION->SITZKRIEG->AT_WAR */
 	for (cn = 1; cn < MAXNOC; cn++) {
-	    if ((cnp = getnatp(cn)) == 0)
+	    if (!(cnp = getnatp(cn)))
 		break;
 	    for (cn2 = 1; cn2 < MAXNOC; cn2++) {
 		if (cn2 == cn)

src/lib/update/nav_ship.c

@@ -284,7 +284,7 @@ nav_ship(struct shpstr *sp)
 	    cp = BestShipPath(buf, sp->shp_x, sp->shp_y,
 			      sp->shp_destx[0], sp->shp_desty[0],
 			      sp->shp_own);
-	    if (cp == 0) {
+	    if (!cp) {
 		wu(0, cnum,
 		   "%s bad path, ship put on standby\n", prship(sp));
 		sp->shp_autonav |= AN_STANDBY;