lsearch(3C)         (C Programming Language Utilities)          lsearch(3C)


   NAME
         lsearch, lfind - linear search and update

   SYNOPSIS
         #include <search.h>

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

         void *lfind (const void *key, const void *base,
                      sizet *nelp, sizet 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.

   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>



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   lsearch(3C)         (C Programming Language Utilities)          lsearch(3C)


               #define TABSIZE 50
               #define ELSIZE 120

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

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

   SEE ALSO
         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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