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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.h>

       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 structure, 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_val-ues(3). ldap_get_values(3).
       ues(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 strcasecmp or its friends for cmp).  You can, however,  pass
       the function ldap_sort_strcasecmp() 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 sort-ing sorting
       ing 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 <ldap.h> 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 2.3.27                                  2006/08/19                                     LDAP_SORT(3)