LDAP_SORT(3)                                                                         LDAP_SORT(3)



NAME
       ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp - LDAP sorting routines

LIBRARY
       OpenLDAP LDAP (libldap, -lldap)

SYNOPSIS
       #include 

       ldap_sort_entries(ld, chain, attr, cmp)
       LDAP *ld;
       LDAPMessage **chain;
       char *attr;
       int (*cmp)();

       ldap_sort_values(ld, vals, cmp)
       LDAP *ld;
       char **vals;
       int (*cmp)();

       ldap_sort_strcasecmp(a, b)
       char *a;
       char *b;

DESCRIPTION
       These routines are used to sort lists of entries and values retrieved from an LDAP server.
       ldap_sort_entries() is used to sort a chain of entries retrieved from an LDAP search  call
       either  by DN or by some arbitrary attribute in the entries.  It takes ld, the LDAP struc-
       ture, which is only used for error reporting, chain, the list of entries  as  returned  by
       ldap_search_s(3)  or ldap_result(3).  attr is the attribute to use as a key in the sort or
       NULL to sort by DN, and cmp is the comparison function to use when  comparing  values  (or
       individual DN components if sorting by DN).  In this case, cmp should be a function taking
       two single values of the attr to sort by, and returning a value less than zero,  equal  to
       zero,  or  greater  than zero, depending on whether the first argument is less than, equal
       to, or greater than the second argument.  The convention is the same as used by  qsort(3),
       which is called to do the actual sorting.

       ldap_sort_values()  is  used  to  sort  an  array  of values from an entry, as returned by
       ldap_get_values(3).  It takes the LDAP connection structure ld, the  array  of  values  to
       sort vals, and cmp, the comparison function to use during the sort.  Note that cmp will be
       passed a pointer to each element in the vals array, so if you pass the normal char **  for
       this  parameter,  cmp  should  take two char **'s as arguments (i.e., you cannot pass str-
       casecmp or its friends for cmp).  You  can,  however,  pass  the  function  ldap_sort_str-
       casecmp() for this purpose.

       For example:

            LDAP *ld;
            LDAPMessage *res;

            /*
             * ... call to ldap_search_s(), fill in res,
             * retrieve sn attr ...
             */

            /* now sort the entries on surname attribute */
            if ( ldap_sort_entries( ld, &res, "sn",
                      ldap_sort_strcasecmp ) != 0 )
                 ldap_perror( ld, "ldap_sort_entries" );

NOTES
       The  ldap_sort_entries()  routine  applies  the  comparison  function to each value of the
       attribute in the array as returned by a call to ldap_get_values(3), until  a  mismatch  is
       found.   This  works fine for single-valued attributes, but may produce unexpected results
       for multi-valued attributes.  When sorting by DN, the comparison function is applied to an
       exploded  version  of the DN, without types.  The return values for all of these functions
       are declared in the  header file.  Some routines may dynamically allocate  memory.
       Callers  are responsible for freeing such memory using the supplied deallocation routines.

SEE ALSO
       ldap(3), ldap_search(3), ldap_result(3), qsort(3)

ACKNOWLEDGEMENTS
       OpenLDAP is developed and maintained by The OpenLDAP  Project  (http://www.openldap.org/).
       OpenLDAP is derived from University of Michigan LDAP 3.3 Release.



OpenLDAP 2.2.13                             2004/06/10                               LDAP_SORT(3)