.

[gnulib.git] / lib / backupfile.c

diff --git a/lib/backupfile.c b/lib/backupfile.c
index cf883fd..2ca5125 100644 (file)
--- a/lib/backupfile.c
+++ b/lib/backupfile.c
@@ -12,8 +12,8 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+   along with this program; if not, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
 
 /* David MacKenzie <djm@gnu.ai.mit.edu>.
    Some algorithms adapted from GNU Emacs. */
@@ -63,13 +63,22 @@ char *malloc ();
 #endif
 
 #if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
-# define ISASCII(c) 1
+# define IN_CTYPE_DOMAIN(c) 1
 #else
-# define ISASCII(c) isascii(c)
+# define IN_CTYPE_DOMAIN(c) isascii(c)
 #endif
 
-#define ISDIGIT(c) (ISASCII ((unsigned char) (c)) \
-                   && isdigit ((unsigned char) (c)))
+#define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
+
+/* ISDIGIT differs from ISDIGIT_LOCALE, as follows:
+   - Its arg may be any int or unsigned int; it need not be an unsigned char.
+   - It's guaranteed to evaluate its argument exactly once.
+   - It's typically faster.
+   Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
+   only '0' through '9' are digits.  Prefer ISDIGIT to ISDIGIT_LOCALE unless
+   it's important to use the locale's definition of `digit' even when the
+   host does not conform to Posix.  */
+#define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
 
 #if defined (HAVE_UNISTD_H)
 #include <unistd.h>