STRXFRM(3)                 POSIX Programmer's Manual                STRXFRM(3)



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

NAME
       strxfrm, strxfrm_l -- string transformation

SYNOPSIS
       #include <string.h>

       size_t strxfrm(char *restrict s1, const char *restrict s2, size_t _n);
       size_t strxfrm_l(char *restrict s1, const char *restrict s2,
           size_t _n, locale_t locale);

DESCRIPTION
       For strxfrm(): 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 strxfrm() and strxfrm___l() functions shall transform the string
       pointed to by s2 and place the resulting string into the array pointed
       to by s1.  The transformation is such that if strcmp() is applied to
       two transformed strings, it shall return a value greater than, equal
       to, or less than 0, corresponding to the result of strcoll() or
       strcoll___l(), respectively, applied to the same two original strings
       with the same locale.  No more than _n bytes are placed into the
       resulting array pointed to by s1, including the terminating NUL
       character. If _n is 0, s1 is permitted to be a null pointer. If copying
       takes place between objects that overlap, the behavior is undefined.

       The strxfrm() and strxfrm___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
       strxfrm() or strxfrm___l(), then check errno.

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

RETURN VALUE
       Upon successful completion, strxfrm() and strxfrm___l() shall return the
       length of the transformed string (not including the terminating NUL
       character). If the value returned is _n or more, the contents of the
       array pointed to by s1 are unspecified.

       On error, strxfrm() and strxfrm___l() may set errno but no return value
       is reserved to indicate an error.

ERRORS
       These functions may fail if:

       EINVAL The string pointed to by the s2 argument contains characters
              outside the domain of the collating sequence.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The transformation function is such that two transformed strings can be
       ordered by strcmp() as appropriate to collating sequence information in
       the current locale (category LC__COLLATE).

       The fact that when _n is 0 s1 is permitted to be a null pointer is
       useful to determine the size of the s1 array prior to making the
       transformation.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       strcmp(), strcoll()

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



IEEE/The Open Group                  2017                           STRXFRM(3)
