PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       wctrans, wctrans_l — define character mapping

SYNOPSIS

       #include <wctype.h>

       wctrans_t wctrans(const char *charclass);
       wctrans_t wctrans_l(const char *charclass, locale_t locale);

DESCRIPTION

       For  wctrans():  The  functionality  described  on this reference page is aligned with the
       ISO C standard. Any conflict  between  the  requirements  described  here  and  the  ISO C
       standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard.

       The  wctrans()  and  wctrans_l()  functions  are defined for valid character mapping names
       identified in the current  locale.  The  charclass  is  a  string  identifying  a  generic
       character  mapping  name for which codeset-specific information is required. The following
       character mapping names are defined in all locales: tolower and toupper.

       These functions shall return a value of type wctrans_t, which can be used  as  the  second
       argument to subsequent calls of towctrans() and towctrans_l().

       The  wctrans()  and wctrans_l() functions shall determine values of wctrans_t according to
       the rules of the coded character set defined  by  character  mapping  information  in  the
       current locale or in the locale represented by locale, respectively (category LC_CTYPE).

       The  values returned by wctrans() shall be valid until a call to setlocale() that modifies
       the category LC_CTYPE.

       The values returned by wctrans_l() shall be valid only in calls to  towctrans_l()  with  a
       locale represented by locale with the same LC_CTYPE category value.

       The  behavior  is  undefined  if  the locale argument to wctrans_l() is the special locale
       object LC_GLOBAL_LOCALE or is not a valid locale object handle.

RETURN VALUE

       The wctrans() and wctrans_l() functions shall return 0 and may set errno to  indicate  the
       error  if  the  given character mapping name is not valid for the current locale (category
       LC_CTYPE); otherwise, they shall return a non-zero object of type wctrans_t  that  can  be
       used in calls to towctrans() and towctrans_l().

ERRORS

       These functions may fail if:

       EINVAL The  character  mapping  name  pointed  to by charclass is not valid in the current
              locale.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       towctrans()

       The Base Definitions volume of POSIX.1‐2017, <wctype.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1-2017,  Standard  for  Information Technology -- Portable Operating System Interface
       (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C)  2018  by
       the  Institute  of  Electrical  and Electronics Engineers, Inc and The Open Group.  In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most  likely  to  have
       been  introduced  during  the conversion of the source files to man page format. To report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .