STRCOLL(3P) POSIX Programmer's Manual STRCOLL(3P)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
strcoll, strcoll_l — string comparison using collating information
SYNOPSIS
#include <string.h>
int strcoll(const char *s1, const char *s2);
int strcoll_l(const char *s1, const char *s2,
locale_t locale);
DESCRIPTION
For strcoll(): 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 strcoll() and strcoll_l() functions shall compare the string
pointed to by s1 to the string pointed to by s2, both interpreted as
appropriate to the LC_COLLATE category of the current locale, or of the
locale represented by locale, respectively.
The strcoll() and strcoll_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
strcoll(), or strcoll_l() then check errno.
The behavior is undefined if the locale argument to strcoll_l() is the
special locale object LC_GLOBAL_LOCALE or is not a valid locale object
handle.
RETURN VALUE
Upon successful completion, strcoll() shall return an integer greater
than, equal to, or less than 0, according to whether the string pointed
to by s1 is greater than, equal to, or less than the string pointed to
by s2 when both are interpreted as appropriate to the current locale.
On error, strcoll() may set errno, but no return value is reserved to
indicate an error.
Upon successful completion, strcoll_l() shall return an integer greater
than, equal to, or less than 0, according to whether the string pointed
to by s1 is greater than, equal to, or less than the string pointed to
by s2 when both are interpreted as appropriate to the locale repre‐
sented by locale. On error, strcoll_l() may set errno, but no return
value is reserved to indicate an error.
ERRORS
These functions may fail if:
EINVAL The s1 or s2 arguments contain characters outside the domain of
the collating sequence.
The following sections are informative.
EXAMPLES
Comparing Nodes
The following example uses an application-defined function, node_com‐
pare(), to compare two nodes based on an alphabetical ordering of the
string field.
#include <string.h>
...
struct node { /* These are stored in the table. */
char *string;
int length;
};
...
int node_compare(const void *node1, const void *node2)
{
return strcoll(((const struct node *)node1)->string,
((const struct node *)node2)->string);
}
...
APPLICATION USAGE
The strxfrm() and strcmp() functions should be used for sorting large
lists.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOalphasort(), strcmp(), strxfrm()
The Base Definitions volume of POSIX.1‐2008, <string.h>
COPYRIGHT
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 Electri‐
cal 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 https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 STRCOLL(3P)
