ldap_sort(3)

     LDAP_SORT(3)             OpenLDAP 2.1.12             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_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 strcasecmp or its friends

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     LDAP_SORT(3)             OpenLDAP 2.1.12             LDAP_SORT(3)

          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 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
          <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.

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