


      LSEARCH(3C)                 (UNIX 5.2)                LSEARCH(3C)



      NAME
           lsearch, lfind - linear search and update

      SYNTAX
           #include <stdio.h>
           #include <search.h>

           char *lsearch ((char *)key, (char *)base, nelp,
           sizeof(*key), compar)
           unsigned *nelp;
           int (*compar)( );

           char *lfind ((char *)key, (char *)base, nelp, sizeof(*key),
           compar)
           unsigned *nelp;
           int (*compar)( );

      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.
           Compar is the name of the comparison function which 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.

      NOTES
           The pointers to the key and the element at the base of the
           table should be of type pointer-to-element, and cast to type
           pointer-to-character.
           The comparison function need not compare every byte, so
           arbitrary data may be contained in the elements in addition
           to the values being compared.
           Although declared as type pointer-to-character, the value
           returned should be cast into type pointer-to-element.

      EXAMPLE
           This fragment will read in < TABSIZE strings of length <
           ELSIZE and store them in a table, eliminating duplicates.

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



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      LSEARCH(3C)                 (UNIX 5.2)                LSEARCH(3C)



                #define TABSIZE 50
                #define ELSIZE 120

                     char line[ELSIZE], tab[TABSIZE][ELSIZE], *lsearch( );
                     unsigned nel = 0;
                     int strcmp( );
                     . . .
                     while (fgets(line, ELSIZE, stdin) != NULL &&
                        nel < TABSIZE)
                          (void) lsearch(line, (char *)tab, &nel,
                                 ELSIZE, strcmp);
                     . . .

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

      DIAGNOSTICS
           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.

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































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