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.
For wcsxfrm(): 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.1‐2008 defers to the ISO C standard.
The wcsxfrm() and wcsxfrm_l() functions shall transform the wide-
character string pointed to by ws2 and place the resulting wide-
character string into the array pointed to by ws1. The
transformation shall be such that if wcscmp() is applied to two
transformed wide strings, it shall return a value greater than, equal
to, or less than 0, corresponding to the result of wcscoll() and
wcscoll_l() applied to the same two original wide-character strings,
and the same LC_COLLATE category of the current locale or the locale
object locale, respectively. No more than n wide-character codes
shall be placed into the resulting array pointed to by ws1, including
the terminating null wide-character code. If n is 0, ws1 is permitted
to be a null pointer. If copying takes place between objects that
overlap, the behavior is undefined.
The wcsxfrm() and wcsxfrm_l() functions shall not change the setting
of errno if successful.
Since no return value is reserved to indicate an error, an
application wishing to check for error situations should set errno to
0, then call wcsxfrm() or wcsxfrm_l(), then check errno.
The behavior is undefined if the locale argument to wcsxfrm_l() is
the special locale object LC_GLOBAL_LOCALE or is not a valid locale
The wcsxfrm() and wcsxfrm_l() functions shall return the length of
the transformed wide-character string (not including the terminating
null wide-character code). If the value returned is n or more, the
contents of the array pointed to by ws1 are unspecified.
On error, the wcsxfrm() and wcsxfrm_l() functions may set errno, but
no return value is reserved to indicate an error.
The transformation function is such that two transformed wide-
character strings can be ordered by wcscmp() as appropriate to
collating sequence information in the current locale (category
The fact that when n is 0 ws1 is permitted to be a null pointer is
useful to determine the size of the ws1 array prior to making the
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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
IEEE/The Open Group 2013 WCSXFRM(3P)