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  LSEARCH(3C)     (C Programming Language Utilities)    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
       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.


  Page 1                                                   May 1989

  LSEARCH(3C)     (C Programming Language Utilities)    LSEARCH(3C)



       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 less than TABSIZE strings of
       length less than ELSIZE and store them in a table,
       eliminating 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)
                      (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.

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




  Page 2                                                   May 1989