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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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STRCOLL(3P) POSIX Programmer's Manual STRCOLL(3P)
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.
strcoll, strcoll_l — string comparison using collating information
#include <string.h>
int strcoll(const char *s1, const char *s2);
int strcoll_l(const char *s1, const char *s2,
locale_t locale);
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.1‐2017 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.
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 represented by locale. On error,
strcoll_l() may set errno, but no return value is reserved to
indicate an error.
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.
Comparing Nodes
The following example uses an application-defined function,
node_compare(), 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);
}
...
The strxfrm() and strcmp() functions should be used for sorting
large lists.
None.
None.
alphasort(3p), strcmp(3p), strxfrm(3p)
The Base Definitions volume of POSIX.1‐2017, string.h(0p)
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 STRCOLL(3P)
Pages that refer to this page: string.h(0p), alphasort(3p), localeconv(3p), setlocale(3p), strxfrm(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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