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

       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 .