use "#if ..." consistently instead of "#ifdef" and "#ifndef" * configure.ac, Doxyfile.in, make_int.cc, Backend.cc, BaseControl.cc, ButtonControl.cc, Canvas.cc, CheckBoxControl.cc, Container.cc, ContextMenu.cc, EditControl.cc, Figure.cc, FigureWindow.cc, GLCanvas.cc, KeyMap.cc, ListBoxControl.cc, Logger.cc, Menu.cc, MouseModeActionGroup.cc, Object.cc, ObjectFactory.cc, ObjectProxy.cc, Panel.cc, PopupMenuControl.cc, PushButtonControl.cc, PushTool.cc, QtHandlesUtils.cc, RadioButtonControl.cc, SliderControl.cc, TextControl.cc, TextEdit.cc, ToggleButtonControl.cc, ToggleTool.cc, ToolBar.cc, __init_qt__.cc, annotation-dialog.cc, gl-select.cc, module.mk, color-picker.cc, dialog.cc, documentation-dock-widget.cc, files-dock-widget.cc, find-files-dialog.cc, find-files-model.cc, history-dock-widget.cc, liboctgui-build-info.in.cc, file-editor-tab.cc, file-editor.cc, find-dialog.cc, marker.cc, marker.h, octave-qscintilla.cc, octave-txt-lexer.cc, main-window.cc, octave-cmd.cc, octave-dock-widget.cc, octave-gui.cc, octave-interpreter.cc, octave-qt-link.cc, parser.cc, webinfo.cc, resource-manager.cc, settings-dialog.cc, shortcut-manager.cc, terminal-dock-widget.cc, thread-manager.cc, welcome-wizard.cc, workspace-model.cc, workspace-view.cc, build-env.in.cc, Cell.cc, __contourc__.cc, __dispatch__.cc, __dsearchn__.cc, __ichol__.cc, __ilu__.cc, __lin_interpn__.cc, __luinc__.cc, __magick_read__.cc, __pchip_deriv__.cc, __qp__.cc, balance.cc, besselj.cc, betainc.cc, bitfcns.cc, bsxfun.cc, c-file-ptr-stream.cc, c-file-ptr-stream.h, cdisplay.c, cdisplay.h, cellfun.cc, coct-hdf5-types.c, colloc.cc, comment-list.cc, conv2.cc, daspk.cc, dasrt.cc, dassl.cc, data.cc, debug.cc, defaults.cc, defaults.in.h, defun.cc, det.cc, dirfns.cc, display.cc, dlmread.cc, dot.cc, dynamic-ld.cc, eig.cc, ellipj.cc, error.cc, errwarn.cc, event-queue.cc, fft.cc, fft2.cc, fftn.cc, file-io.cc, filter.cc, find.cc, ft-text-renderer.cc, gammainc.cc, gcd.cc, getgrent.cc, getpwent.cc, getrusage.cc, givens.cc, gl-render.cc, gl2ps-print.cc, graphics.cc, gripes.cc, hash.cc, help.cc, hess.cc, hex2num.cc, input.cc, inv.cc, jit-ir.cc, jit-ir.h, jit-typeinfo.cc, jit-typeinfo.h, jit-util.cc, jit-util.h, kron.cc, load-path.cc, load-save.cc, lookup.cc, ls-ascii-helper.cc, ls-hdf5.cc, ls-mat-ascii.cc, ls-mat4.cc, ls-mat5.cc, ls-oct-binary.cc, ls-oct-text.cc, ls-oct-text.h, ls-utils.cc, lsode.cc, lu.cc, mappers.cc, matrix_type.cc, max.cc, mex.cc, mex.h, mexproto.h, mgorth.cc, nproc.cc, oct-errno.in.cc, oct-fstrm.cc, oct-hdf5-types.cc, oct-hdf5-types.h, oct-hist.cc, oct-iostrm.cc, oct-lvalue.cc, oct-map.cc, oct-prcstrm.cc, oct-procbuf.cc, oct-stdstrm.h, oct-stream.cc, oct-strstrm.cc, oct-tex-lexer.in.ll, oct-tex-parser.in.yy, octave-link.cc, ordschur.cc, pager.cc, pinv.cc, pr-output.cc, procstream.cc, profiler.cc, psi.cc, pt-jit.cc, pt-jit.h, quad.cc, quadcc.cc, qz.cc, rand.cc, rcond.cc, regexp.cc, schur.cc, sighandlers.cc, sighandlers.h, siglist.c, siglist.h, sparse-xdiv.cc, sparse-xpow.cc, sparse.cc, spparms.cc, sqrtm.cc, str2double.cc, strfind.cc, strfns.cc, sub2ind.cc, svd.cc, sylvester.cc, symtab.cc, syscalls.cc, sysdep.cc, text-renderer.cc, time.cc, toplev.cc, tril.cc, tsearch.cc, txt-eng.cc, typecast.cc, urlwrite.cc, utils.cc, variables.cc, xdiv.cc, xgl2ps.c, xnorm.cc, xpow.cc, zfstream.cc, zfstream.h, __delaunayn__.cc, __eigs__.cc, __fltk_uigetfile__.cc, __glpk__.cc, __init_fltk__.cc, __init_gnuplot__.cc, __osmesa_print__.cc, __voronoi__.cc, amd.cc, audiodevinfo.cc, audioread.cc, ccolamd.cc, chol.cc, colamd.cc, convhulln.cc, dmperm.cc, fftw.cc, qr.cc, symbfact.cc, symrcm.cc, liboctinterp-build-info.in.cc, mkbuiltins, mkops, ov-base.cc, ov-bool-mat.cc, ov-bool-sparse.cc, ov-bool.cc, ov-builtin.cc, ov-cell.cc, ov-ch-mat.cc, ov-class.cc, ov-classdef.cc, ov-colon.cc, ov-complex.cc, ov-cs-list.cc, ov-cx-diag.cc, ov-cx-mat.cc, ov-cx-sparse.cc, ov-dld-fcn.cc, ov-fcn-handle.cc, ov-fcn-inline.cc, ov-fcn.cc, ov-float.cc, ov-flt-complex.cc, ov-flt-cx-diag.cc, ov-flt-cx-mat.cc, ov-flt-re-diag.cc, ov-flt-re-mat.cc, ov-int16.cc, ov-int32.cc, ov-int64.cc, ov-int8.cc, ov-java.cc, ov-lazy-idx.cc, ov-mex-fcn.cc, ov-null-mat.cc, ov-oncleanup.cc, ov-perm.cc, ov-range.cc, ov-re-diag.cc, ov-re-mat.cc, ov-re-sparse.cc, ov-scalar.cc, ov-str-mat.cc, ov-struct.cc, ov-typeinfo.cc, ov-uint16.cc, ov-uint32.cc, ov-uint64.cc, ov-uint8.cc, ov-usr-fcn.cc, ov-usr-fcn.h, ov.cc, ovl.cc, octave.cc, octave.h, op-b-b.cc, op-b-bm.cc, op-b-sbm.cc, op-bm-b.cc, op-bm-bm.cc, op-bm-sbm.cc, op-cdm-cdm.cc, op-cdm-cm.cc, op-cdm-dm.cc, op-cdm-m.cc, op-cell.cc, op-chm.cc, op-class.cc, op-cm-cdm.cc, op-cm-cm.cc, op-cm-cs.cc, op-cm-dm.cc, op-cm-m.cc, op-cm-s.cc, op-cm-scm.cc, op-cm-sm.cc, op-cs-cm.cc, op-cs-cs.cc, op-cs-m.cc, op-cs-s.cc, op-cs-scm.cc, op-cs-sm.cc, op-dm-cdm.cc, op-dm-cm.cc, op-dm-dm.cc, op-dm-m.cc, op-dm-scm.cc, op-dm-sm.cc, op-dm-template.cc, op-dms-template.cc, op-double-conv.cc, op-fcdm-fcdm.cc, op-fcdm-fcm.cc, op-fcdm-fdm.cc, op-fcdm-fm.cc, op-fcm-fcdm.cc, op-fcm-fcm.cc, op-fcm-fcs.cc, op-fcm-fdm.cc, op-fcm-fm.cc, op-fcm-fs.cc, op-fcn.cc, op-fcs-fcm.cc, op-fcs-fcs.cc, op-fcs-fm.cc, op-fcs-fs.cc, op-fdm-fcdm.cc, op-fdm-fcm.cc, op-fdm-fdm.cc, op-fdm-fm.cc, op-float-conv.cc, op-fm-fcdm.cc, op-fm-fcm.cc, op-fm-fcs.cc, op-fm-fdm.cc, op-fm-fm.cc, op-fm-fs.cc, op-fs-fcm.cc, op-fs-fcs.cc, op-fs-fm.cc, op-fs-fs.cc, op-i16-i16.cc, op-i32-i32.cc, op-i64-i64.cc, op-i8-i8.cc, op-int-concat.cc, op-int-conv.cc, op-m-cdm.cc, op-m-cm.cc, op-m-cs.cc, op-m-dm.cc, op-m-m.cc, op-m-s.cc, op-m-scm.cc, op-m-sm.cc, op-pm-pm.cc, op-pm-scm.cc, op-pm-sm.cc, op-pm-template.cc, op-range.cc, op-s-cm.cc, op-s-cs.cc, op-s-m.cc, op-s-s.cc, op-s-scm.cc, op-s-sm.cc, op-sbm-b.cc, op-sbm-bm.cc, op-sbm-sbm.cc, op-scm-cm.cc, op-scm-cs.cc, op-scm-m.cc, op-scm-s.cc, op-scm-scm.cc, op-scm-sm.cc, op-sm-cm.cc, op-sm-cs.cc, op-sm-m.cc, op-sm-s.cc, op-sm-scm.cc, op-sm-sm.cc, op-str-m.cc, op-str-s.cc, op-str-str.cc, op-struct.cc, op-ui16-ui16.cc, op-ui32-ui32.cc, op-ui64-ui64.cc, op-ui8-ui8.cc, lex.ll, oct-parse.in.yy, pt-arg-list.cc, pt-array-list.cc, pt-assign.cc, pt-binop.cc, pt-bp.cc, pt-cbinop.cc, pt-cell.cc, pt-check.cc, pt-classdef.cc, pt-cmd.cc, pt-colon.cc, pt-const.cc, pt-decl.cc, pt-eval.cc, pt-except.cc, pt-exp.cc, pt-fcn-handle.cc, pt-funcall.cc, pt-id.cc, pt-idx.cc, pt-jump.cc, pt-loop.cc, pt-loop.h, pt-mat.cc, pt-misc.cc, pt-pr-code.cc, pt-select.cc, pt-stmt.cc, pt-unop.cc, pt.cc, token.cc, Array-jit.cc, Array-tc.cc, version.cc, Array-C.cc, Array-b.cc, Array-ch.cc, Array-d.cc, Array-f.cc, Array-fC.cc, Array-i.cc, Array-idx-vec.cc, Array-s.cc, Array-str.cc, Array-util.cc, Array-voidp.cc, Array.cc, CColVector.cc, CDiagMatrix.cc, CMatrix.cc, CNDArray.cc, CRowVector.cc, CSparse.cc, MArray-C.cc, MArray-d.cc, MArray-f.cc, MArray-fC.cc, MArray-i.cc, MArray-s.cc, MSparse-C.cc, MSparse-d.cc, MatrixType.cc, PermMatrix.cc, Range.cc, Sparse-C.cc, Sparse-b.cc, Sparse-d.cc, boolMatrix.cc, boolNDArray.cc, boolSparse.cc, chMatrix.cc, chNDArray.cc, dColVector.cc, dDiagMatrix.cc, dMatrix.cc, dNDArray.cc, dRowVector.cc, dSparse.cc, dim-vector.cc, dim-vector.h, fCColVector.cc, fCDiagMatrix.cc, fCMatrix.cc, fCNDArray.cc, fCRowVector.cc, fColVector.cc, fDiagMatrix.cc, fMatrix.cc, fNDArray.cc, fRowVector.cc, idx-vector.cc, int16NDArray.cc, int32NDArray.cc, int64NDArray.cc, int8NDArray.cc, uint16NDArray.cc, uint32NDArray.cc, uint64NDArray.cc, uint8NDArray.cc, Faddeeva.cc, blaswrap.c, cquit.c, f77-extern.cc, f77-fcn.c, f77-fcn.h, lo-error.c, lo-error.h, quit.cc, quit.h, liboctave-build-info.in.cc, CollocWt.cc, DASPK.cc, DASRT.cc, DASSL.cc, EIG.cc, LSODE.cc, ODES.cc, Quad.cc, aepbalance.cc, chol.cc, eigs-base.cc, fEIG.cc, gepbalance.cc, hess.cc, lo-mappers.cc, lo-specfun.cc, lu.cc, oct-convn.cc, oct-fftw.cc, oct-norm.cc, oct-rand.cc, oct-spparms.cc, qr.cc, qrp.cc, randmtzig.cc, randpoisson.cc, schur.cc, sparse-chol.cc, sparse-dmsolve.cc, sparse-lu.cc, sparse-qr.cc, svd.cc, mk-ops.awk, mx-defs.h, dir-ops.cc, file-ops.cc, file-stat.cc, lo-sysdep.cc, mach-info.cc, oct-env.cc, oct-group.cc, oct-passwd.cc, oct-syscalls.cc, oct-time.cc, oct-uname.cc, pathlen.h, syswait.h, cmd-edit.cc, cmd-hist.cc, data-conv.cc, f2c-main.c, glob-match.cc, kpse.cc, lo-array-errwarn.cc, lo-array-gripes.cc, lo-cutils.c, lo-cutils.h, lo-ieee.cc, lo-ieee.h, lo-regexp.cc, lo-utils.cc, oct-base64.cc, oct-glob.cc, oct-inttypes.cc, oct-inttypes.h, oct-locbuf.cc, oct-mutex.cc, oct-rl-edit.c, oct-rl-edit.h, oct-rl-hist.c, oct-rl-hist.h, oct-shlib.cc, oct-sort.cc, pathsearch.cc, singleton-cleanup.cc, sparse-sort.cc, sparse-util.cc, statdefs.h, str-vec.cc, unwind-prot.cc, url-transfer.cc, acinclude.m4, display-available.c, display-available.h, main-cli.cc, main-gui.cc, main.in.cc, mkoctfile.in.cc, octave-build-info.in.cc, octave-config.in.cc, shared-fcns.h: Use "#if ..." consistently instead of "#ifdef" and "#ifndef".

--- a/liboctave/util/kpse.cc	Tue May 17 11:32:53 2016 -0400
+++ b/liboctave/util/kpse.cc	Tue May 17 12:09:30 2016 -0400
@@ -53,13 +53,13 @@
 #include <fcntl.h>
 #include <dirent.h>
 #elif defined (WIN32)
-#ifndef _MSC_VER
+#if ! defined (_MSC_VER)
 #define __STDC__ 1
 #include "win32lib.h"
 #endif
 #endif /* not WIN32 */
 
-#ifdef __DJGPP__
+#if defined (__DJGPP__)
 #include <fcntl.h>      /* for long filenames' stuff */
 #include <dir.h>        /* for 'getdisk' */
 #include <io.h>         /* for 'setmode' */
@@ -67,7 +67,7 @@
 }
 
 /* Some drivers have partially integrated kpathsea changes.  */
-#ifndef KPATHSEA
+#if ! defined (KPATHSEA)
 #define KPATHSEA 32
 #endif
 
@@ -85,7 +85,7 @@
 #define ST_NLINK_TRICK
 #endif /* either not DOSISH or __DJGPP__ */
 
-#ifdef OS2
+#if defined (OS2)
 #define access ln_access
 #define fopen ln_fopen
 #define rename ln_rename
@@ -96,8 +96,8 @@
    filenames and environment variable paths.  */
 
 /* What separates filename components?  */
-#ifndef DIR_SEP
-#ifdef DOSISH
+#if ! defined (DIR_SEP)
+#if defined (DOSISH)
 /* Either \'s or 's work.  Wayne Sullivan's web2pc prefers /, so we'll
    go with that.  */
 #define DIR_SEP '/'
@@ -112,13 +112,14 @@
 #endif /* not DOSISH */
 #endif /* not DIR_SEP */
 
-#ifndef IS_DIR_SEP
+#if ! defined (IS_DIR_SEP)
 #define IS_DIR_SEP(ch) ((ch) == DIR_SEP)
 #endif
-#ifndef IS_DEVICE_SEP /* No 'devices' on, e.g., Unix.  */
+#if ! defined (IS_DEVICE_SEP)
+/* No 'devices' on, e.g., Unix.  */
 #define IS_DEVICE_SEP(ch) 0
 #endif
-#ifndef NAME_BEGINS_WITH_DEVICE
+#if ! defined (NAME_BEGINS_WITH_DEVICE)
 #define NAME_BEGINS_WITH_DEVICE(name) 0
 #endif
 
@@ -148,18 +149,18 @@
 
 /* Most likely the system will truncate filenames if it is not POSIX,
    and so we can use the BSD value here.  */
-#ifndef _POSIX_NAME_MAX
+#if ! defined (_POSIX_NAME_MAX)
 #define _POSIX_NAME_MAX 255
 #endif
 
-#ifndef NAME_MAX
+#if ! defined (NAME_MAX)
 #define NAME_MAX _POSIX_NAME_MAX
 #endif
 
 #include <cctype>
 
 /* What separates elements in environment variable path lists?  */
-#ifndef ENV_SEP
+#if ! defined (ENV_SEP)
 #if defined (SEPCHAR) && defined (SEPCHAR_STR)
 #define ENV_SEP SEPCHAR
 #define ENV_SEP_STRING SEPCHAR_STR
@@ -172,7 +173,7 @@
 #endif /* not DOS */
 #endif /* not ENV_SEP */
 
-#ifndef IS_ENV_SEP
+#if ! defined (IS_ENV_SEP)
 #define IS_ENV_SEP(ch) ((ch) == ENV_SEP)
 #endif
 
@@ -183,12 +184,12 @@
 /* Cheat and define this as a manifest constant no matter what, instead
    of using pathconf.  I forget why we want to do this.  */
 
-#ifndef _POSIX_PATH_MAX
+#if ! defined (_POSIX_PATH_MAX)
 #define _POSIX_PATH_MAX 255
 #endif
 
-#ifndef PATH_MAX
-#ifdef MAXPATHLEN
+#if ! defined (PATH_MAX)
+#if defined (MAXPATHLEN)
 #define PATH_MAX MAXPATHLEN
 #else
 #define PATH_MAX _POSIX_PATH_MAX
@@ -196,7 +197,7 @@
 #endif /* not PATH_MAX */
 
 /* If NO_DEBUG is defined (not recommended), skip all this.  */
-#ifndef NO_DEBUG
+#if ! defined (NO_DEBUG)
 
 /* OK, we'll have tracing support.  */
 #define KPSE_DEBUG
@@ -230,7 +231,7 @@
 
 #endif /* not NO_DEBUG */
 
-#ifdef KPSE_DEBUG
+#if defined (KPSE_DEBUG)
 static unsigned int kpathsea_debug = 0;
 #endif
 
@@ -243,11 +244,11 @@
  *      Define all the symbols that apply correctly.
  */
 
-#ifndef DOSISH
+#if ! defined (DOSISH)
 #define DOSISH
 #endif
 
-#ifndef MAXPATHLEN
+#if ! defined (MAXPATHLEN)
 #define MAXPATHLEN      _MAX_PATH
 #endif
 
@@ -300,7 +301,7 @@
     } \
   while (0)
 
-#ifndef WIN32
+#if ! defined (WIN32)
 static void xclosedir (DIR *d);
 #endif
 
@@ -419,7 +420,7 @@
     if (key == p->key)
       ret.append (p->value);
 
-#ifdef KPSE_DEBUG
+#if defined (KPSE_DEBUG)
   if (KPSE_DEBUG_P (KPSE_DEBUG_HASH))
     {
       DEBUGF1 ("hash_lookup (%s) =>", key.c_str ());
@@ -520,7 +521,7 @@
   if (! tmp.empty ())
     ret = kpse_var_expand (tmp);
 
-#ifdef KPSE_DEBUG
+#if defined (KPSE_DEBUG)
   if (KPSE_DEBUG_P (KPSE_DEBUG_VARS))
     DEBUGF2 ("variable: %s = %s\n", var.c_str (),
              tmp.empty () ? "(nil)" :  tmp.c_str ());
@@ -570,7 +571,7 @@
    regular file, as it is potentially useful to read fifo's or some
    kinds of devices.  */
 
-#ifdef WIN32
+#if defined (WIN32)
 static inline bool
 READABLE (const std::string& fn, struct stat&)
 {
@@ -604,7 +605,7 @@
     {
       ret = name;
 
-#ifdef ENAMETOOLONG
+#if defined (ENAMETOOLONG)
     }
   else if (errno == ENAMETOOLONG)
     {
@@ -645,11 +646,11 @@
   size_t len = filename.length ();
 
   int absolute = (len > 0 && IS_DIR_SEP (filename[0]))
-#ifdef DOSISH
+#if defined (DOSISH)
                  /* Novell allows non-alphanumeric drive letters. */
                  || (len > 0 && IS_DEVICE_SEP (filename[1]))
 #endif /* DOSISH */
-#ifdef WIN32
+#if defined (WIN32)
                  /* UNC names */
                  || (len > 1 && filename[0] == '\\' && filename[1] == '\\')
 #endif
@@ -1231,7 +1232,7 @@
          OS/2 doesn't have this concept.  */
     }
   else
-#ifdef HAVE_PWD_H
+#if defined (HAVE_PWD_H)
     {
       unsigned c = 2;
 
@@ -1920,7 +1921,7 @@
           std::string db_file = db_dirs[j] + atry;
           bool matched = match (db_file, path_elt);
 
-#ifdef KPSE_DEBUG
+#if defined (KPSE_DEBUG)
           if (KPSE_DEBUG_P (KPSE_DEBUG_SEARCH))
             DEBUGF3 ("db:match (%s,%s) = %d\n",
                      db_file.c_str (), path_elt.c_str (), matched);
@@ -2056,7 +2057,7 @@
 static bool
 dir_p (const std::string& fn)
 {
-#ifdef WIN32
+#if defined (WIN32)
   unsigned int fa = GetFileAttributes (fn.c_str ());
   return (fa != 0xFFFFFFFF && (fa & FILE_ATTRIBUTE_DIRECTORY));
 #else
@@ -2146,7 +2147,7 @@
    subdirectories of ELT (up to ELT_LENGTH, which must be a /) to
    STR_LIST_PTR.  */
 
-#ifdef WIN32
+#if defined (WIN32)
 
 /* Shared across recursive calls, it acts like a stack. */
 static std::string dirname;
@@ -2175,7 +2176,7 @@
 
       link_table[fn] = ret;
 
-#ifdef KPSE_DEBUG
+#if defined (KPSE_DEBUG)
       if (KPSE_DEBUG_P (KPSE_DEBUG_STAT))
         DEBUGF2 ("dir_links (%s) => %ld\n", fn.c_str (), ret);
 #endif
@@ -2190,7 +2191,7 @@
 do_subdir (str_llist_type *str_list_ptr, const std::string& elt,
            unsigned elt_length, const std::string& post)
 {
-#ifdef WIN32
+#if defined (WIN32)
   WIN32_FIND_DATA find_file_data;
   HANDLE hnd;
   int proceed;
@@ -2300,16 +2301,16 @@
                  the only alternative I know of is to stat every entry
                  in the directory, and that is unacceptably slow.
 
-                 The #ifdef here makes all this configurable at
+                 The #if here makes all this configurable at
                  compile-time, so that if we're using VMS directories or
                  some such, we can still find subdirectories, even if it
                  is much slower.  */
-#ifdef ST_NLINK_TRICK
+#if defined (ST_NLINK_TRICK)
               if (links != 2)
 #endif /* not ST_NLINK_TRICK */
                 /* All criteria are met; find subdirectories.  */
                 do_subdir (str_list_ptr, name, potential_len, post);
-#ifdef ST_NLINK_TRICK
+#if defined (ST_NLINK_TRICK)
               else if (post.empty ())
                 /* Nothing to match, no recursive subdirectories to
                    look for: we're done with this branch.  Add it.  */
@@ -2407,7 +2408,7 @@
      made with the same ELT.  */
   cache (elt, ret);
 
-#ifdef KPSE_DEBUG
+#if defined (KPSE_DEBUG)
   if (KPSE_DEBUG_P (KPSE_DEBUG_EXPAND))
     {
       DEBUGF1 ("path element %s =>", elt.c_str ());
@@ -2425,7 +2426,7 @@
   return ret;
 }
 
-#ifndef WIN32
+#if ! defined (WIN32)
 void
 xclosedir (DIR *d)
 {
@@ -2566,16 +2567,19 @@
 
 /* Can't think of when it would be useful to change these (and the
    diagnostic messages assume them), but ... */
-#ifndef IS_VAR_START /* starts all variable references */
+#if ! defined (IS_VAR_START)
+/* starts all variable references */
 #define IS_VAR_START(c) ((c) == '$')
 #endif
-#ifndef IS_VAR_CHAR  /* variable name constituent */
+#if ! defined (IS_VAR_CHAR)
+/* variable name constituent */
 #define IS_VAR_CHAR(c) (isalnum (c) || (c) == '_')
 #endif
-#ifndef IS_VAR_BEGIN_DELIMITER /* start delimited variable name (after $) */
+#if ! defined (IS_VAR_BEGIN_DELIMITER)
+/* start delimited variable name (after $) */
 #define IS_VAR_BEGIN_DELIMITER(c) ((c) == '{')
 #endif
-#ifndef IS_VAR_END_DELIMITER
+#if ! defined (IS_VAR_END_DELIMITER)
 #define IS_VAR_END_DELIMITER(c) ((c) == '}')
 #endif