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

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

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 (getstring(prompt, buf) == 0)
+    if (!input || !*input) {
+	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 = getstring(prompt, buf)) == 0)
+    if (!arg || !*arg) {
+	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 = getstring("(sects)? ", buf)) == 0)
+    if (!str || !*str) {
+	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) {