2000-05-21 23:22:28 +02:00
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@node Character Handling, String and Array Utilities, Memory, Top
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1998-07-13 14:29:13 +02:00
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@c %MENU% Character testing and conversion functions
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1995-02-18 02:27:10 +01:00
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@chapter Character Handling
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Programs that work with characters and strings often need to classify a
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character---is it alphabetic, is it a digit, is it whitespace, and so
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on---and perform case conversion operations on characters. The
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functions in the header file @file{ctype.h} are provided for this
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purpose.
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@pindex ctype.h
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Since the choice of locale and character set can alter the
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classifications of particular character codes, all of these functions
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are affected by the current locale. (More precisely, they are affected
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by the locale currently selected for character classification---the
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@code{LC_CTYPE} category; see @ref{Locale Categories}.)
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1999-01-11 21:13:43 +01:00
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The @w{ISO C} standard specifies two different sets of functions. The
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one set works on @code{char} type characters, the other one on
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1999-06-16 17:44:59 +02:00
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@code{wchar_t} wide characters (@pxref{Extended Char Intro}).
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1995-02-18 02:27:10 +01:00
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1999-01-11 21:13:43 +01:00
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@menu
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* Classification of Characters:: Testing whether characters are
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letters, digits, punctuation, etc.
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* Case Conversion:: Case mapping, and the like.
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* Classification of Wide Characters:: Character class determination for
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wide characters.
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* Using Wide Char Classes:: Notes on using the wide character
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classes.
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* Wide Character Case Conversion:: Mapping of wide characters.
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1995-02-18 02:27:10 +01:00
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@end menu
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@node Classification of Characters, Case Conversion, , Character Handling
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@section Classification of Characters
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@cindex character testing
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@cindex classification of characters
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@cindex predicates on characters
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@cindex character predicates
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This section explains the library functions for classifying characters.
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For example, @code{isalpha} is the function to test for an alphabetic
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character. It takes one argument, the character to test, and returns a
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nonzero integer if the character is alphabetic, and zero otherwise. You
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would use it like this:
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@smallexample
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if (isalpha (c))
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printf ("The character `%c' is alphabetic.\n", c);
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@end smallexample
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Each of the functions in this section tests for membership in a
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particular class of characters; each has a name starting with @samp{is}.
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Each of them takes one argument, which is a character to test, and
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returns an @code{int} which is treated as a boolean value. The
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character argument is passed as an @code{int}, and it may be the
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1996-12-08 09:01:13 +01:00
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constant value @code{EOF} instead of a real character.
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1995-02-18 02:27:10 +01:00
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The attributes of any given character can vary between locales.
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@xref{Locales}, for more information on locales.@refill
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These functions are declared in the header file @file{ctype.h}.
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@pindex ctype.h
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@cindex lower-case character
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@comment ctype.h
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1996-12-08 09:01:13 +01:00
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@comment ISO
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1995-02-18 02:27:10 +01:00
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@deftypefun int islower (int @var{c})
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1999-01-11 21:13:43 +01:00
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Returns true if @var{c} is a lower-case letter. The letter need not be
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from the Latin alphabet, any alphabet representable is valid.
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1995-02-18 02:27:10 +01:00
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@end deftypefun
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@cindex upper-case character
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@comment ctype.h
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1996-12-08 09:01:13 +01:00
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@comment ISO
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1995-02-18 02:27:10 +01:00
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@deftypefun int isupper (int @var{c})
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1999-01-11 21:13:43 +01:00
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Returns true if @var{c} is an upper-case letter. The letter need not be
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from the Latin alphabet, any alphabet representable is valid.
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1995-02-18 02:27:10 +01:00
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@end deftypefun
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@cindex alphabetic character
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@comment ctype.h
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1996-12-08 09:01:13 +01:00
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@comment ISO
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1995-02-18 02:27:10 +01:00
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@deftypefun int isalpha (int @var{c})
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Returns true if @var{c} is an alphabetic character (a letter). If
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@code{islower} or @code{isupper} is true of a character, then
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@code{isalpha} is also true.
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In some locales, there may be additional characters for which
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Update.
1997-11-11 21:30 Ulrich Drepper <drepper@cygnus.com>
* include/sys/stat.h: Define stat, fstat, lstat and *64 variants
as macros so the the library compiles correctly even without
optimization.
* io/fstat.c: Undef fstat.
* io/fstat64.c: Undef fstat64
* io/lstat.c: Undef lstat.
* io/lstat64.c: Undef lstat64
* io/stat.c: Undef stat.
* io/stat64.c: Undef stat64
* io/fts.c: Include <include/sys/stat.h> to get macro definitions.
* io/ftw.c: Likewise.
* io/getdirname.c: Likewise.
* Makefile (install): Run test-installation.pl if possible.
* db2/Makefile: Update from db-2.3.12.
* db2/db.h: Likewise.
* db2/db_int.h: Likewise.
* db2/btree/bt_cursor.c: Likewise.
* db2/btree/bt_delete.c: Likewise.
* db2/btree/bt_open.c: Likewise.
* db2/btree/bt_put.c: Likewise.
* db2/btree/bt_rec.c: Likewise.
* db2/btree/bt_recno.c: Likewise.
* db2/btree/bt_search.c: Likewise.
* db2/btree/bt_split.c: Likewise.
* db2/btree/bt_stat.c: Likewise.
* db2/btree/btree.src: Likewise.
* db2/btree/btree_auto.c: Likewise.
* db2/btree/bt_cursor.c: Likewise.
* db2/btree/bt_delete.c: Likewise.
* db2/btree/bt_open.c: Likewise.
* db2/btree/bt_put.c: Likewise.
* db2/btree/bt_rec.c: Likewise.
* db2/btree/bt_recno.c: Likewise.
* db2/btree/bt_search.c: Likewise.
* db2/btree/bt_split.c: Likewise.
* db2/btree/bt_stat.c: Likewise.
* db2/btree/btree.src: Likewise.
* db2/btree/btree_auto.c: Likewise.
* db2/common/db_appinit.c: Likewise.
* db2/common/db_apprec.c: Likewise.
* db2/common/db_byteorder.c: Likewise.
* db2/common/db_region.c: Likewise.
* db2/db/db.c: Likewise
* db2/db/db.src: Likewise
* db2/db/db_auto.c: Likewise
* db2/db/db_dispatch.c: Likewise
* db2/db/db_dup.c: Likewise
* db2/db/db_overflow.c: Likewise
* db2/db/db_pr.c: Likewise
* db2/db/db_rec.c: Likewise
* db2/db/db_ret.c: Likewise
* db2/db/db_thread.c: Likewise
* db2/db185/db185.c: Likewise.
* db2/hash/hash.c: Likewise.
* db2/hash/hash.src: Likewise.
* db2/hash/hash_auto.c: Likewise.
* db2/hash/hash_dup.c: Likewise.
* db2/hash/hash_page.c: Likewise.
* db2/hash/hash_rec.c: Likewise.
* db2/include/btree_auto.h: Likewise.
* db2/include/btree_ext.h: Likewise.
* db2/include/clib_ext.h: Likewise.
* db2/include/common_ext.h: Likewise.
* db2/include/db.h.src: Likewise.
* db2/include/db_am.h: Likewise.
* db2/include/db_auto.h: Likewise.
* db2/include/db_cxx.h: Likewise.
* db2/include/db_ext.h: Likewise.
* db2/include/db_int.h.src: Likewise.
* db2/include/hash.h: Likewise.
* db2/include/hash_auto.h: Likewise.
* db2/include/hash_ext.h: Likewise.
* db2/include/lock.h: Likewise.
* db2/include/lock_ext.h: Likewise.
* db2/include/log.h: Likewise.
* db2/include/log_ext.h: Likewise.
* db2/include/mp.h: Likewise.
* db2/include/mp_ext.h: Likewise.
* db2/include/mutex_ext.h: Likewise.
* db2/include/os_ext.h: Likewise.
* db2/include/os_func.h: Likewise.
* db2/include/txn.h: Likewise.
* db2/include/txn_ext.h: Likewise.
* db2/lock/lock.c: Likewise.
* db2/lock/lock_deadlock.c: Likewise.
* db2/log/log.c: Likewise.
* db2/log/log_archive.c: Likewise.
* db2/log/log_auto.c: Likewise.
* db2/log/log_findckp.c: Likewise.
* db2/log/log_get.c: Likewise.
* db2/log/log_put.c: Likewise.
* db2/log/log_rec.c: Likewise.
* db2/log/log_register.c: Likewise.
* db2/mp/mp_bh.c: Likewise.
* db2/mp/mp_fget.c: Likewise.
* db2/mp/mp_fopen.c: Likewise.
* db2/mp/mp_fput.c: Likewise.
* db2/mp/mp_fset.c: Likewise.
* db2/mp/mp_open.c: Likewise.
* db2/mp/mp_pr.c: Likewise.
* db2/mp/mp_region.c: Likewise.
* db2/mp/mp_sync.c: Likewise.
* db2/mutex/mutex.c: Likewise.
* db2/os/os_abs.c: Likewise.
* db2/os/os_dir.c: Likewise.
* db2/os/os_fid.c: Likewise.
* db2/os/os_fsync.c: Likewise.
* db2/os/os_func.c: Likewise.
* db2/os/os_map.c: Likewise.
* db2/os/os_oflags.c: Likewise.
* db2/os/os_open.c: Likewise.
* db2/os/os_rpath.c: Likewise.
* db2/os/os_rw.c: Likewise.
* db2/os/os_seek.c: Likewise.
* db2/os/os_sleep.c: Likewise.
* db2/os/os_stat.c: Likewise.
* db2/os/os_unlink.c: Likewise.
* db2/progs/db_deadlock/db_deadlock.c: Likewise.
* db2/progs/db_dump/db_dump.c: Likewise.
* db2/progs/db_load/db_load.c: Likewise.
* db2/progs/db_recover/db_recover.c: Likewise.
* db2/progs/db_stat/db_stat.c: Likewise.
* db2/txn/txn.c: Likewise.
* db2/txn/txn_auto.c: Likewise.
* db2/txn/txn_rec.c: Likewise.
* db2/os/db_os_abs.c: Removed.
* db2/os/db_os_dir.c: Removed.
* db2/os/db_os_fid.c: Removed.
* db2/os/db_os_lseek.c: Removed.
* db2/os/db_os_mmap.c: Removed.
* db2/os/db_os_open.c: Removed.
* db2/os/db_os_rw.c: Removed.
* db2/os/db_os_sleep.c: Removed.
* db2/os/db_os_stat.c: Removed.
* db2/os/db_os_unlink.c: Removed.
* libio/stdio.h (fopen): Add __restrict to parameters.
* manual/process.texi (system): Describe behaviour for NULL argument.
* stdio-common/printf-parse.h: Parse hh modifier.
* stdio-common/vfprintf.c: Handle hh modifier.
* stdio-common/vfscanf.c: Likewise.
* manual/stdio.texi: Describe hh modifier for scanf/printf.
* math/complex.h: Don't define _Imaginary_I, but instead _Complex_I.
gcc does no yet know the `imaginary' keyword.
* math/test-math.c: Add little test for know gcc bug.
* math/tgmath.h: Make complex versions of log10() only available
if __USE_GNU.
* stdlib/test-canon.c: Fix typo.
* sysdeps/generic/setenv.c: Avoid compilation warnings.
Reported by Jim Meyering.
* sysdeps/generic/bits/errno.h: EILSEQ is an ISO C error number.
* sysdeps/mach/hurd/bits/errno.h: Likewise.
* sysdeps/standalone/bits/errno.h: Likewise.
* sysdeps/unix/sysv/linux/bits/errno.h: Likewise.
* sysdeps/i386/i586/memcpy.S: New file.
* sysdeps/i386/i586/mempcpy.S: New file.
* sysdeps/i386/i586/memset.S: Fix typo.
* sysdeps/posix/getcwd.c: Define HAVE_MEMPCPY for _LIBC. Add casts.
* sysdeps/posix/system.c: Add comment to explain code.
* sysdeps/wordsize-32/inttypes.h: Include <stddef.h> for wchar_t.
Define PTRDIFF_{MIN,MAX}, SIG_ATOMIC_{MIN,MAX}, SIZE_MAX,
WCHAR_{MIN,MAX}, WINT_{MIN,MAX}.
Define wcstoimax, wcstoumax.
* sysdeps/wordsize-64/inttypes.h: Likewise.
* wcsmbs/wchar.h: Define WCHAR_{MIN,MAX} if not already defined.
Declare __wcsto{l,ul,ll,ull}_internal only if not already done.
* time/Makefile (routines): Add strfxtime.
* time/strftime.c: Implement %F and %f format.
* time/strfxtime.c: New file.
* time/time.h: Define new types and symbols from ISO C 9X.
* time/mktime.c: Little comment correction.
1997-11-10 Andreas Jaeger <aj@arthur.rhein-neckar.de>
* sysdeps/libm-ieee754/s_sincosl.c: Fix typo.
* sysdeps/libm-ieee754/s_tanl.c: Fix typo.
* sysdeps/libm-ieee754/s_floorl.c: Correct typos.
* sysdeps/libm-ieee754/e_remainderl.c: Replace
EXTRACT_LDOUBLE_WORDS by GET_LDOUBLE_WORDS.
* sysdeps/libm-ieee754/e_atan2l.c: Replace EXTRACT_LDOUBLE_WORDS
by GET_LDOUBLE_WORDS.
* sysdeps/libm-ieee754/s_scalbnl.c: Replace ";" by "," for correct
variable declaration.
* sysdeps/libm-ieee754/s_scalblnl.c: Likewise.
* sysdeps/libm-ieee754/s_lrint.c (__lrint): Correct function.
* math/libm-test.c (sqrt_test): Add test for sqrt (0.25).
(asin_test): Add more test.
1997-11-10 23:34 Ulrich Drepper <drepper@cygnus.com>
* sysdeps/libm-ieee754/e_asin.c: Add braces to make code clearer
and to not confuse the poor compiler.
* sysdeps/libm-ieee754/e_asinf.c: Likewise.
Reported by vertex@cagent.com.
1997-11-09 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* elf/dl-lookup.c (do_lookup): Don't accept the base version if we
require a specific one.
* libio/oldfreopen.c: Bind old symbols to version GLIBC_2.0.
* libio/oldiofopen.c: Likewise.
* libio/oldstdfiles.c: Likewise.
* libc.map: Export them.
1997-11-10 07:40 H.J. Lu <hjl@gnu.ai.mit.edu>
* stdlib/exit.c (exit): Handle recursive calls to exit ().
1997-11-09 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/m68k/fpu/s_llrint.c: Fixed to take double argument
instead of long double.
* sysdeps/m68k/fpu/s_llrintf.c: New file.
* sysdeps/m68k/fpu/s_llrintl.c: New file.
* sysdeps/libm-ieee754/s_llrint.c: Make compilable and fix
overflow condition.
* sysdeps/libm-ieee754/s_llrintf.c: Fix overflow condition.
* sysdeps/libm-ieee754/s_llrintl.c: Likewise.
* sysdeps/libm-ieee754/s_llround.c: Likewise.
* sysdeps/libm-ieee754/s_llroundf.c: Likewise.
* sysdeps/libm-ieee754/s_llroundl.c: Likewise.
* sysdeps/libm-ieee754/s_lrint.c: Likewise.
* sysdeps/libm-ieee754/s_lrintf.c: Likewise.
* sysdeps/libm-ieee754/s_lrintl.c: Likewise.
* sysdeps/libm-ieee754/s_lround.c: Likewise.
* sysdeps/libm-ieee754/s_lroundf.c: Likewise.
* sysdeps/libm-ieee754/s_lroundl.c: Likewise.
* math/libm-test.c: Test all three variants of lrint and llrint.
Fix typos in lround and llround tests. Add tests for boundary
cases for lrint and llround.
1997-11-08 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* manual/arith.texi: Misc doc fixes.
* manual/ctype.texi: Likewise.
* manual/pattern.texi: Likewise.
* manual/terminal.texi: Likewise.
1997-11-08 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/unix/sysv/linux/xstatconv.c: Use struct assignment
instead of memcpy to let the compiler use whatever it regards as
optimal.
* sysdeps/unix/sysv/linux/alpha/xstatconv.c: Likewise.
1997-11-08 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/unix/sysv/linux/Makefile (sysdep_headers)
[$(subdir)=misc]: Add sys/prctl.h.
* sysdeps/unix/sysv/linux/Dist: Distribute it.
1997-11-08 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* io/ftwtest-sh: Don't use the unknown which command, instead try
pwd as /bin/pwd and /usr/bin/pwd.
1997-11-08 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* manual/maint.texi (Tools for Installation): Don't recommend
broken version 3.76.1 of make.
(Porting): Fix wording.
1997-11-06 06:13 H.J. Lu <hjl@gnu.ai.mit.edu>
* config.make.in (build-pic-default): New, defined with
pic_default.
* configure.in (pic_default): New, set to yes if PIC is
default.
* Makeconfig (CPPFLAGS-.o, CPPFLAGS-.op, CPPFLAGS-.og,
CPPFLAGS-.ob): Add -DPIC if $(build-pic-default) is yes.
1997-11-09 18:15 Ulrich Drepper <drepper@cygnus.com>
* Makerules (libc.so): Fix typo.
* csu/Makefile (CFLAGS-initfini.s): Correctly fix moving function
definition. Patch by Zack Weinberg <zack@rabi.phys.columbia.edu>.
* stdlib/strtod.c: Handle numbers like 0.0e10000 correctly which
produce 0.0. Reported by Joe Keane <jgk@jgk.org>.
* sysdeps/libm-ieee754/s_ceill.c: Fix typos.
* sysdeps/libm-ieee754/s_llrint.c: Correct code, it never worked.
1997-11-06 07:00 H.J. Lu <hjl@gnu.ai.mit.edu>
* sysdeps/unix/sysv/i386/i686/time.S: Removed.
1997-11-08 14:07 Thorsten Kukuk <kukuk@vt.uni-paderborn.de>
* nis/libnsl.map: Add __do_niscall2 for nis_cachemgr.
* nis/nis_call.c: Set UDP resend timeout correct.
* nis/nss_compat/compat-grp.c: Rewritten to make it faster.
* nis/nss_compat/compat-pwd.c: Likewise.
* nis/nss_compat/compat-spwd.c: Likewise.
* nis/ypclnt.c: Fix UDP resend timeout, fix yp_bind/do_ypcall
interaction.
* inet/protocols/routed.h: Include sys/socket.h.
* inet/protocols/talkd.h: Likewise.
* inet/protocols/timed.h: Include rpc/types.h.
* sunrpc/rpc/pmap_clnt.h: Include rpc/clnt.h.
1997-11-06 01:39 Ulrich Drepper <drepper@cygnus.com>
* Makerules (libc.so): Add missing closing brace.
1997-11-05 Brendan Kehoe <brendan@lisa.cygnus.com>
* libio.h (__P): Name its arg `p' instead of `params'.
This was added solely to work around problems with
the definition of __P in the Solaris math.h header.
1997-11-12 01:06:02 +01:00
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|
@code{isalpha} is true---letters which are neither upper case nor lower
|
1995-02-18 02:27:10 +01:00
|
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case. But in the standard @code{"C"} locale, there are no such
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additional characters.
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@end deftypefun
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@cindex digit character
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@cindex decimal digit character
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|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int isdigit (int @var{c})
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Returns true if @var{c} is a decimal digit (@samp{0} through @samp{9}).
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@end deftypefun
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@cindex alphanumeric character
|
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|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int isalnum (int @var{c})
|
|
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|
Returns true if @var{c} is an alphanumeric character (a letter or
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number); in other words, if either @code{isalpha} or @code{isdigit} is
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true of a character, then @code{isalnum} is also true.
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@end deftypefun
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@cindex hexadecimal digit character
|
|
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|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int isxdigit (int @var{c})
|
|
|
|
Returns true if @var{c} is a hexadecimal digit.
|
|
|
|
Hexadecimal digits include the normal decimal digits @samp{0} through
|
|
|
|
@samp{9} and the letters @samp{A} through @samp{F} and
|
|
|
|
@samp{a} through @samp{f}.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex punctuation character
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int ispunct (int @var{c})
|
|
|
|
Returns true if @var{c} is a punctuation character.
|
|
|
|
This means any printing character that is not alphanumeric or a space
|
|
|
|
character.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex whitespace character
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int isspace (int @var{c})
|
|
|
|
Returns true if @var{c} is a @dfn{whitespace} character. In the standard
|
|
|
|
@code{"C"} locale, @code{isspace} returns true for only the standard
|
|
|
|
whitespace characters:
|
|
|
|
|
|
|
|
@table @code
|
|
|
|
@item ' '
|
|
|
|
space
|
|
|
|
|
|
|
|
@item '\f'
|
|
|
|
formfeed
|
|
|
|
|
|
|
|
@item '\n'
|
|
|
|
newline
|
|
|
|
|
|
|
|
@item '\r'
|
|
|
|
carriage return
|
|
|
|
|
|
|
|
@item '\t'
|
|
|
|
horizontal tab
|
|
|
|
|
|
|
|
@item '\v'
|
|
|
|
vertical tab
|
|
|
|
@end table
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex blank character
|
|
|
|
@comment ctype.h
|
|
|
|
@comment GNU
|
|
|
|
@deftypefun int isblank (int @var{c})
|
|
|
|
Returns true if @var{c} is a blank character; that is, a space or a tab.
|
|
|
|
This function is a GNU extension.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex graphic character
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int isgraph (int @var{c})
|
|
|
|
Returns true if @var{c} is a graphic character; that is, a character
|
|
|
|
that has a glyph associated with it. The whitespace characters are not
|
|
|
|
considered graphic.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex printing character
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int isprint (int @var{c})
|
|
|
|
Returns true if @var{c} is a printing character. Printing characters
|
|
|
|
include all the graphic characters, plus the space (@samp{ }) character.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex control character
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int iscntrl (int @var{c})
|
|
|
|
Returns true if @var{c} is a control character (that is, a character that
|
|
|
|
is not a printing character).
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex ASCII character
|
|
|
|
@comment ctype.h
|
|
|
|
@comment SVID, BSD
|
|
|
|
@deftypefun int isascii (int @var{c})
|
|
|
|
Returns true if @var{c} is a 7-bit @code{unsigned char} value that fits
|
|
|
|
into the US/UK ASCII character set. This function is a BSD extension
|
|
|
|
and is also an SVID extension.
|
|
|
|
@end deftypefun
|
|
|
|
|
1999-01-11 21:13:43 +01:00
|
|
|
@node Case Conversion, Classification of Wide Characters, Classification of Characters, Character Handling
|
1995-02-18 02:27:10 +01:00
|
|
|
@section Case Conversion
|
|
|
|
@cindex character case conversion
|
|
|
|
@cindex case conversion of characters
|
|
|
|
@cindex converting case of characters
|
|
|
|
|
|
|
|
This section explains the library functions for performing conversions
|
|
|
|
such as case mappings on characters. For example, @code{toupper}
|
|
|
|
converts any character to upper case if possible. If the character
|
|
|
|
can't be converted, @code{toupper} returns it unchanged.
|
|
|
|
|
|
|
|
These functions take one argument of type @code{int}, which is the
|
|
|
|
character to convert, and return the converted character as an
|
|
|
|
@code{int}. If the conversion is not applicable to the argument given,
|
|
|
|
the argument is returned unchanged.
|
|
|
|
|
1996-12-08 09:01:13 +01:00
|
|
|
@strong{Compatibility Note:} In pre-@w{ISO C} dialects, instead of
|
1995-02-18 02:27:10 +01:00
|
|
|
returning the argument unchanged, these functions may fail when the
|
|
|
|
argument is not suitable for the conversion. Thus for portability, you
|
|
|
|
may need to write @code{islower(c) ? toupper(c) : c} rather than just
|
|
|
|
@code{toupper(c)}.
|
|
|
|
|
|
|
|
These functions are declared in the header file @file{ctype.h}.
|
|
|
|
@pindex ctype.h
|
|
|
|
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int tolower (int @var{c})
|
|
|
|
If @var{c} is an upper-case letter, @code{tolower} returns the corresponding
|
|
|
|
lower-case letter. If @var{c} is not an upper-case letter,
|
|
|
|
@var{c} is returned unchanged.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@comment ctype.h
|
1996-12-08 09:01:13 +01:00
|
|
|
@comment ISO
|
1995-02-18 02:27:10 +01:00
|
|
|
@deftypefun int toupper (int @var{c})
|
1999-01-11 21:13:43 +01:00
|
|
|
If @var{c} is a lower-case letter, @code{toupper} returns the corresponding
|
1995-02-18 02:27:10 +01:00
|
|
|
upper-case letter. Otherwise @var{c} is returned unchanged.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@comment ctype.h
|
|
|
|
@comment SVID, BSD
|
|
|
|
@deftypefun int toascii (int @var{c})
|
|
|
|
This function converts @var{c} to a 7-bit @code{unsigned char} value
|
|
|
|
that fits into the US/UK ASCII character set, by clearing the high-order
|
|
|
|
bits. This function is a BSD extension and is also an SVID extension.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@comment ctype.h
|
|
|
|
@comment SVID
|
|
|
|
@deftypefun int _tolower (int @var{c})
|
|
|
|
This is identical to @code{tolower}, and is provided for compatibility
|
|
|
|
with the SVID. @xref{SVID}.@refill
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@comment ctype.h
|
|
|
|
@comment SVID
|
|
|
|
@deftypefun int _toupper (int @var{c})
|
|
|
|
This is identical to @code{toupper}, and is provided for compatibility
|
|
|
|
with the SVID.
|
|
|
|
@end deftypefun
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
|
|
|
|
@node Classification of Wide Characters, Using Wide Char Classes, Case Conversion, Character Handling
|
|
|
|
@section Character class determination for wide characters
|
|
|
|
|
|
|
|
The second amendment to @w{ISO C89} defines functions to classify wide
|
1999-08-27 21:52:08 +02:00
|
|
|
characters. Although the original @w{ISO C89} standard already defined
|
|
|
|
the type @code{wchar_t}, no functions operating on them were defined.
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
The general design of the classification functions for wide characters
|
1999-08-27 21:52:08 +02:00
|
|
|
is more general. It allows extensions to the set of available
|
|
|
|
classifications, beyond those which are always available. The POSIX
|
|
|
|
standard specifies how extensions can be made, and this is already
|
1999-06-16 17:44:59 +02:00
|
|
|
implemented in the GNU C library implementation of the @code{localedef}
|
|
|
|
program.
|
1999-01-11 21:13:43 +01:00
|
|
|
|
1999-08-27 21:52:08 +02:00
|
|
|
The character class functions are normally implemented with bitsets,
|
|
|
|
with a bitset per character. For a given character, the appropriate
|
|
|
|
bitset is read from a table and a test is performed as to whether a
|
|
|
|
certain bit is set. Which bit is tested for is determined by the
|
|
|
|
class.
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
For the wide character classification functions this is made visible.
|
1999-08-27 21:52:08 +02:00
|
|
|
There is a type classification type defined, a function to retrieve this
|
|
|
|
value for a given class, and a function to test whether a given
|
|
|
|
character is in this class, using the classification value. On top of
|
|
|
|
this the normal character classification functions as used for
|
1999-01-11 21:13:43 +01:00
|
|
|
@code{char} objects can be defined.
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftp {Data type} wctype_t
|
|
|
|
The @code{wctype_t} can hold a value which represents a character class.
|
1999-08-27 21:52:08 +02:00
|
|
|
The only defined way to generate such a value is by using the
|
1999-01-11 21:13:43 +01:00
|
|
|
@code{wctype} function.
|
|
|
|
|
|
|
|
@pindex wctype.h
|
|
|
|
This type is defined in @file{wctype.h}.
|
|
|
|
@end deftp
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun wctype_t wctype (const char *@var{property})
|
|
|
|
The @code{wctype} returns a value representing a class of wide
|
|
|
|
characters which is identified by the string @var{property}. Beside
|
|
|
|
some standard properties each locale can define its own ones. In case
|
1999-08-27 21:52:08 +02:00
|
|
|
no property with the given name is known for the current locale
|
|
|
|
selected for the @code{LC_CTYPE} category, the function returns zero.
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
@noindent
|
|
|
|
The properties known in every locale are:
|
|
|
|
|
|
|
|
@multitable @columnfractions .25 .25 .25 .25
|
|
|
|
@item
|
|
|
|
@code{"alnum"} @tab @code{"alpha"} @tab @code{"cntrl"} @tab @code{"digit"}
|
|
|
|
@item
|
|
|
|
@code{"graph"} @tab @code{"lower"} @tab @code{"print"} @tab @code{"punct"}
|
|
|
|
@item
|
|
|
|
@code{"space"} @tab @code{"upper"} @tab @code{"xdigit"}
|
|
|
|
@end multitable
|
|
|
|
|
|
|
|
@pindex wctype.h
|
|
|
|
This function is declared in @file{wctype.h}.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
To test the membership of a character to one of the non-standard classes
|
|
|
|
the @w{ISO C} standard defines a completely new function.
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswctype (wint_t @var{wc}, wctype_t @var{desc})
|
|
|
|
This function returns a nonzero value if @var{wc} is in the character
|
|
|
|
class specified by @var{desc}. @var{desc} must previously be returned
|
|
|
|
by a successful call to @code{wctype}.
|
|
|
|
|
|
|
|
@pindex wctype.h
|
|
|
|
This function is declared in @file{wctype.h}.
|
|
|
|
@end deftypefun
|
|
|
|
|
1999-08-27 21:52:08 +02:00
|
|
|
To make it easier to use the commonly-used classification functions,
|
|
|
|
they are defined in the C library. There is no need to use
|
1999-06-16 17:44:59 +02:00
|
|
|
@code{wctype} if the property string is one of the known character
|
1999-01-11 21:13:43 +01:00
|
|
|
classes. In some situations it is desirable to construct the property
|
1999-08-27 21:52:08 +02:00
|
|
|
strings, and then it is important that @code{wctype} can also handle the
|
1999-01-11 21:13:43 +01:00
|
|
|
standard classes.
|
|
|
|
|
|
|
|
@cindex alphanumeric character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswalnum (wint_t @var{wc})
|
|
|
|
This function returns a nonzero value if @var{wc} is an alphanumeric
|
|
|
|
character (a letter or number); in other words, if either @code{iswalpha}
|
|
|
|
or @code{iswdigit} is true of a character, then @code{iswalnum} is also
|
|
|
|
true.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("alnum"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex alphabetic character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswalpha (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is an alphabetic character (a letter). If
|
|
|
|
@code{iswlower} or @code{iswupper} is true of a character, then
|
|
|
|
@code{iswalpha} is also true.
|
|
|
|
|
|
|
|
In some locales, there may be additional characters for which
|
|
|
|
@code{iswalpha} is true---letters which are neither upper case nor lower
|
|
|
|
case. But in the standard @code{"C"} locale, there are no such
|
|
|
|
additional characters.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("alpha"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex control character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswcntrl (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a control character (that is, a character that
|
|
|
|
is not a printing character).
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("cntrl"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex digit character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswdigit (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a digit (e.g., @samp{0} through @samp{9}).
|
|
|
|
Please note that this function does not only return a nonzero value for
|
|
|
|
@emph{decimal} digits, but for all kinds of digits. A consequence is
|
|
|
|
that code like the following will @strong{not} work unconditionally for
|
|
|
|
wide characters:
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
n = 0;
|
1999-08-27 21:52:08 +02:00
|
|
|
while (iswdigit (*wc))
|
1999-01-11 21:13:43 +01:00
|
|
|
@{
|
|
|
|
n *= 10;
|
|
|
|
n += *wc++ - L'0';
|
|
|
|
@}
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("digit"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex graphic character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswgraph (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a graphic character; that is, a character
|
|
|
|
that has a glyph associated with it. The whitespace characters are not
|
|
|
|
considered graphic.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("graph"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex lower-case character
|
|
|
|
@comment ctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswlower (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a lower-case letter. The letter need not be
|
|
|
|
from the Latin alphabet, any alphabet representable is valid.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("lower"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex printing character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswprint (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a printing character. Printing characters
|
|
|
|
include all the graphic characters, plus the space (@samp{ }) character.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("print"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex punctuation character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswpunct (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a punctuation character.
|
|
|
|
This means any printing character that is not alphanumeric or a space
|
|
|
|
character.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("punct"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex whitespace character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswspace (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a @dfn{whitespace} character. In the standard
|
|
|
|
@code{"C"} locale, @code{iswspace} returns true for only the standard
|
|
|
|
whitespace characters:
|
|
|
|
|
|
|
|
@table @code
|
|
|
|
@item L' '
|
|
|
|
space
|
|
|
|
|
|
|
|
@item L'\f'
|
|
|
|
formfeed
|
|
|
|
|
|
|
|
@item L'\n'
|
|
|
|
newline
|
|
|
|
|
|
|
|
@item L'\r'
|
|
|
|
carriage return
|
|
|
|
|
|
|
|
@item L'\t'
|
|
|
|
horizontal tab
|
|
|
|
|
|
|
|
@item L'\v'
|
|
|
|
vertical tab
|
|
|
|
@end table
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("space"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex upper-case character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswupper (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is an upper-case letter. The letter need not be
|
|
|
|
from the Latin alphabet, any alphabet representable is valid.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("upper"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@cindex hexadecimal digit character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun int iswxdigit (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a hexadecimal digit.
|
|
|
|
Hexadecimal digits include the normal decimal digits @samp{0} through
|
|
|
|
@samp{9} and the letters @samp{A} through @samp{F} and
|
|
|
|
@samp{a} through @samp{f}.
|
|
|
|
|
|
|
|
@noindent
|
|
|
|
This function can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
iswctype (wc, wctype ("xdigit"))
|
|
|
|
@end smallexample
|
|
|
|
|
|
|
|
@pindex wctype.h
|
1999-01-12 01:00:01 +01:00
|
|
|
It is declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
1999-06-16 17:44:59 +02:00
|
|
|
The GNU C library also provides a function which is not defined in the
|
1999-01-11 21:13:43 +01:00
|
|
|
@w{ISO C} standard but which is available as a version for single byte
|
|
|
|
characters as well.
|
|
|
|
|
|
|
|
@cindex blank character
|
|
|
|
@comment wctype.h
|
|
|
|
@comment GNU
|
|
|
|
@deftypefun int iswblank (wint_t @var{wc})
|
|
|
|
Returns true if @var{wc} is a blank character; that is, a space or a tab.
|
|
|
|
This function is a GNU extension. It is declared in @file{wchar.h}.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@node Using Wide Char Classes, Wide Character Case Conversion, Classification of Wide Characters, Character Handling
|
|
|
|
@section Notes on using the wide character classes
|
|
|
|
|
1999-08-27 21:52:08 +02:00
|
|
|
The first note is probably not astonishing but still occasionally a
|
1999-01-11 21:13:43 +01:00
|
|
|
cause of problems. The @code{isw@var{XXX}} functions can be implemented
|
|
|
|
using macros and in fact, the GNU C library does this. They are still
|
|
|
|
available as real functions but when the @file{wctype.h} header is
|
1999-08-27 21:52:08 +02:00
|
|
|
included the macros will be used. This is the same as the
|
1999-01-11 21:13:43 +01:00
|
|
|
@code{char} type versions of these functions.
|
|
|
|
|
1999-06-16 17:44:59 +02:00
|
|
|
The second note covers something new. It can be best illustrated by a
|
|
|
|
(real-world) example. The first piece of code is an excerpt from the
|
|
|
|
original code. It is truncated a bit but the intention should be clear.
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
@smallexample
|
|
|
|
int
|
|
|
|
is_in_class (int c, const char *class)
|
|
|
|
@{
|
|
|
|
if (strcmp (class, "alnum") == 0)
|
|
|
|
return isalnum (c);
|
|
|
|
if (strcmp (class, "alpha") == 0)
|
|
|
|
return isalpha (c);
|
|
|
|
if (strcmp (class, "cntrl") == 0)
|
|
|
|
return iscntrl (c);
|
|
|
|
...
|
|
|
|
return 0;
|
|
|
|
@}
|
|
|
|
@end smallexample
|
|
|
|
|
1999-08-27 21:52:08 +02:00
|
|
|
Now, with the @code{wctype} and @code{iswctype} you can avoid the
|
|
|
|
@code{if} cascades, but rewriting the code as follows is wrong:
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
@smallexample
|
|
|
|
int
|
|
|
|
is_in_class (int c, const char *class)
|
|
|
|
@{
|
|
|
|
wctype_t desc = wctype (class);
|
|
|
|
return desc ? iswctype ((wint_t) c, desc) : 0;
|
|
|
|
@}
|
|
|
|
@end smallexample
|
|
|
|
|
1999-06-16 17:44:59 +02:00
|
|
|
The problem is that it is not guaranteed that the wide character
|
1999-01-11 21:13:43 +01:00
|
|
|
representation of a single-byte character can be found using casting.
|
1999-08-27 21:52:08 +02:00
|
|
|
In fact, usually this fails miserably. The correct solution to this
|
1999-01-11 21:13:43 +01:00
|
|
|
problem is to write the code as follows:
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
int
|
|
|
|
is_in_class (int c, const char *class)
|
|
|
|
@{
|
|
|
|
wctype_t desc = wctype (class);
|
|
|
|
return desc ? iswctype (btowc (c), desc) : 0;
|
|
|
|
@}
|
|
|
|
@end smallexample
|
|
|
|
|
1999-01-22 10:29:52 +01:00
|
|
|
@xref{Converting a Character}, for more information on @code{btowc}.
|
1999-08-27 21:52:08 +02:00
|
|
|
Note that this change probably does not improve the performance
|
1999-01-11 21:13:43 +01:00
|
|
|
of the program a lot since the @code{wctype} function still has to make
|
1999-08-27 21:52:08 +02:00
|
|
|
the string comparisons. It gets really interesting if the
|
|
|
|
@code{is_in_class} function is called more than once for the
|
1999-01-11 21:13:43 +01:00
|
|
|
same class name. In this case the variable @var{desc} could be computed
|
|
|
|
once and reused for all the calls. Therefore the above form of the
|
|
|
|
function is probably not the final one.
|
|
|
|
|
|
|
|
|
|
|
|
@node Wide Character Case Conversion, , Using Wide Char Classes, Character Handling
|
|
|
|
@section Mapping of wide characters.
|
|
|
|
|
1999-08-27 21:52:08 +02:00
|
|
|
The classification functions are also generalized by the @w{ISO C}
|
|
|
|
standard. Instead of just allowing the two standard mappings, a
|
|
|
|
locale can contain others. Again, the @code{localedef} program
|
|
|
|
already supports generating such locale data files.
|
1999-01-11 21:13:43 +01:00
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftp {Data Type} wctrans_t
|
|
|
|
This data type is defined as a scalar type which can hold a value
|
|
|
|
representing the locale-dependent character mapping. There is no way to
|
1999-08-27 21:52:08 +02:00
|
|
|
construct such a value apar from using the return value of the
|
1999-01-11 21:13:43 +01:00
|
|
|
@code{wctrans} function.
|
|
|
|
|
|
|
|
@pindex wctype.h
|
|
|
|
@noindent
|
|
|
|
This type is defined in @file{wctype.h}.
|
|
|
|
@end deftp
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
1999-01-18 10:38:36 +01:00
|
|
|
@deftypefun wctrans_t wctrans (const char *@var{property})
|
1999-01-11 21:13:43 +01:00
|
|
|
The @code{wctrans} function has to be used to find out whether a named
|
|
|
|
mapping is defined in the current locale selected for the
|
1999-08-27 21:52:08 +02:00
|
|
|
@code{LC_CTYPE} category. If the returned value is non-zero, you can use
|
|
|
|
it afterwards in calls to @code{towctrans}. If the return value is
|
1999-01-11 21:13:43 +01:00
|
|
|
zero no such mapping is known in the current locale.
|
|
|
|
|
|
|
|
Beside locale-specific mappings there are two mappings which are
|
|
|
|
guaranteed to be available in every locale:
|
|
|
|
|
|
|
|
@multitable @columnfractions .5 .5
|
|
|
|
@item
|
|
|
|
@code{"tolower"} @tab @code{"toupper"}
|
|
|
|
@end multitable
|
|
|
|
|
|
|
|
@pindex wctype.h
|
|
|
|
@noindent
|
1999-08-27 21:52:08 +02:00
|
|
|
These functions are declared in @file{wctype.h}.
|
1999-01-11 21:13:43 +01:00
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun wint_t towctrans (wint_t @var{wc}, wctrans_t @var{desc})
|
1999-08-27 21:52:08 +02:00
|
|
|
@code{towctrans} maps the input character @var{wc}
|
|
|
|
according to the rules of the mapping for which @var{desc} is a
|
|
|
|
descriptor, and returns the value it finds. @var{desc} must be
|
1999-01-11 21:13:43 +01:00
|
|
|
obtained by a successful call to @code{wctrans}.
|
|
|
|
|
|
|
|
@pindex wctype.h
|
|
|
|
@noindent
|
|
|
|
This function is declared in @file{wctype.h}.
|
|
|
|
@end deftypefun
|
|
|
|
|
1999-08-27 21:52:08 +02:00
|
|
|
For the generally available mappings, the @w{ISO C} standard defines
|
|
|
|
convenient shortcuts so that it is not necessary to call @code{wctrans}
|
1999-01-11 21:13:43 +01:00
|
|
|
for them.
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun wint_t towlower (wint_t @var{wc})
|
|
|
|
If @var{wc} is an upper-case letter, @code{towlower} returns the corresponding
|
|
|
|
lower-case letter. If @var{wc} is not an upper-case letter,
|
|
|
|
@var{wc} is returned unchanged.
|
|
|
|
|
1999-01-12 01:00:01 +01:00
|
|
|
@noindent
|
|
|
|
@code{towlower} can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
towctrans (wc, wctrans ("tolower"))
|
|
|
|
@end smallexample
|
|
|
|
|
1999-01-11 21:13:43 +01:00
|
|
|
@pindex wctype.h
|
|
|
|
@noindent
|
|
|
|
This function is declared in @file{wctype.h}.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
@comment wctype.h
|
|
|
|
@comment ISO
|
|
|
|
@deftypefun wint_t towupper (wint_t @var{wc})
|
|
|
|
If @var{wc} is a lower-case letter, @code{towupper} returns the corresponding
|
|
|
|
upper-case letter. Otherwise @var{wc} is returned unchanged.
|
|
|
|
|
1999-01-12 01:00:01 +01:00
|
|
|
@noindent
|
|
|
|
@code{towupper} can be implemented using
|
|
|
|
|
|
|
|
@smallexample
|
|
|
|
towctrans (wc, wctrans ("toupper"))
|
|
|
|
@end smallexample
|
|
|
|
|
1999-01-11 21:13:43 +01:00
|
|
|
@pindex wctype.h
|
|
|
|
@noindent
|
|
|
|
This function is declared in @file{wctype.h}.
|
|
|
|
@end deftypefun
|
|
|
|
|
|
|
|
The same warnings given in the last section for the use of the wide
|
1999-08-27 21:52:08 +02:00
|
|
|
character classification functions apply here. It is not possible to
|
1999-01-11 21:13:43 +01:00
|
|
|
simply cast a @code{char} type value to a @code{wint_t} and use it as an
|
1999-08-27 21:52:08 +02:00
|
|
|
argument to @code{towctrans} calls.
|