lsearch(3C)                    DG/UX R4.11MU05                   lsearch(3C)


NAME
       lsearch, lfind - linear search and update

SYNOPSIS
       #include <search.h>

       void *lsearch (const void *key, void * base,
            size_t *nelp, size_t width,
            int (*compar) (const void *, const void *));

       void *lfind (const void *key, const void *base,
            size_t *nelp, size_t width,
            int (*compar)(const void *, const void *));

DESCRIPTION
       lsearch is a linear search routine generalized from Knuth (6.1)
       Algorithm S.  It returns a pointer into a table indicating where a
       datum may be found.  If the datum does not occur, it is added at the
       end of the table.

       key points to the datum to be sought in the table.  base points to
       the first element in the table.  nelp points to an integer containing
       the current number of elements in the table.  The integer is
       incremented if the datum is added to the table.  width is the size of
       an element in bytes.

       compar is a pointer to the comparison function that the user must
       supply (strcmp, for example).  It is called with two arguments that
       point to the elements being compared.  The function must return zero
       if the elements are equal and non-zero otherwise.

       lfind is the same as lsearch except that if the datum is not found,
       it is not added to the table.  Instead, a null pointer is returned.


   Considerations for Threads Programming
                     +---------+-----------------------------+
                     |         |                      async- |
                     |function | reentrant   cancel   cancel |
                     |         |             point     safe  |
                     +---------+-----------------------------+
                     |lfind    |     Y         N        N    |
                     |lsearch  |     Y         N        N    |
                     +---------+-----------------------------+

NOTES
       The pointers to the key and the element at the base of the table may
       be pointers to any type.

       The comparison function need not compare every byte, so arbitrary
       data may be contained in the elements in addition to the values being
       compared.

       The value returned should be cast into type pointer-to-element.

EXAMPLE
       This program will read in less than TABSIZE strings of length less
       than ELSIZE and store them in a table, eliminating duplicates, and
       then will print each entry.

              #include <search.h>
              #include <string.h>
              #include <stdlib.h>
              #include <stdio.h>

              #define TABSIZE 50
              #define ELSIZE 120

              main()
              {
                       char line[ELSIZE];   /* buffer to hold input string */
                       char tab[TABSIZE][ELSIZE];    /* table of strings */
                       size_t nel = 0;               /* number of entries in tab */
                       int i;

                       while (fgets(line, ELSIZE, stdin) != NULL &&
                                   nel < TABSIZE)
                                   (void) lsearch(line, tab, &nel, ELSIZE, strcmp);
                       for( i = 0; i < nel; i++ )
                                   (void)fputs(tab[i], stdout);
                       return 0;
              }

SEE ALSO
       reentrant(3), bsearch(3C), hsearch(3C), string(3C),
       tsearch(3C).

NOTES
       If the searched-for datum is found, both lsearch and lfind return a
       pointer to it.  Otherwise, lfind returns NULL and lsearch returns a
       pointer to the newly added element.

       Undefined results can occur if there is not enough room in the table
       to add a new item.


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