LSEARCH(3C)          INTERACTIVE UNIX System          LSEARCH(3C)



          NAME
               lsearch, lfind - linear search and update

          SYNOPSIS
               #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
               The lsearch function 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.

          EXAMPLE
               This fragment will read in less than TABSIZE strings of
               length less than ELSIZE and store them in a table, eliminat-
               ing duplicates.

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

                    #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)


          Rev. C Software Development Set                            Page 1

          LSEARCH(3C)          INTERACTIVE UNIX System          LSEARCH(3C)



                              (void) lsearch(line, (char *)tab, &nel,
                                     ELSIZE, strcmp);
                         . . .

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

          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.

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




























          Rev. C Software Development Set                            Page 2