WCSXFRM(3POSIX)

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
wcsxfrm, wcsxfrm_l — wide-character string transformation

SYNOPSIS

#include <wchar.h>

size_t wcsxfrm(wchar_t *restrict ws1, const wchar_t *restrict ws2,
    size_t n);
size_t wcsxfrm_l(wchar_t *restrict ws1, const wchar_t *restrict ws2,
    size_t n, locale_t locale);

DESCRIPTION
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.1-2017 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 object handle.

RETURN VALUE
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.

ERRORS
These functions may fail if:

EINVAL
    The wide-character string pointed to by ws2 contains wide-character codes outside the domain of the collating sequence.

The following sections are informative.

EXAMPLES
None.

APPLICATION USAGE
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 LC_COLLATE).

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 transformation.

RATIONALE
None.

FUTURE DIRECTIONS
None.

SEE ALSO
wcscmp(), wcscoll()

The Base Definitions volume of POSIX.1-2017, <wchar.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 .