# define IN_CTYPE_DOMAIN(c) isascii(c)
#endif
-#if !defined (isxdigit) && !defined (HAVE_ISXDIGIT)
+#if !defined (isxdigit) && !defined (HAVE_ISXDIGIT) && !defined (__cplusplus)
# define isxdigit(c) (isdigit((c)) || ((c) >= 'a' && (c) <= 'f') || ((c) >= 'A' && (c) <= 'F'))
#endif