cleanup, use '\0' and NULL

src/frontend/inp.c

@@ -455,7 +455,7 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
                     /* all commands from within .control section */
                     } else {
                         s = dd->li_line;
-                        dd->li_line = 0; /* SJB - prevent line_free() freeing the string (now pointed at by wl->wl_word) */
+                        dd->li_line = NULL; /* SJB - prevent line_free() freeing the string (now pointed at by wl->wl_word) */
                     }
                     controls = wl_cons(s, controls);
                 }

src/spicelib/parser/inppas2.c

@@ -253,7 +253,7 @@ void INPpas2(CKTcircuit *ckt, card * data, INPtables * tab, TSKtask *task)
 	    return;
 	    break;
 
-	case 0:
+	case '\0':
 	    break;
 
 	default: