LSEARCH(3C)                          SysV                          LSEARCH(3C)



NAME
     lsearch, lfind - linear search and update

SYNOPSIS
     #include <sys/types.h>
     #include <search.h>

     void *lsearch (key, base, nelp, sizeof, compar)
     const void *key,
     const void *base,
     size_t *nelp,
     size_t sizeof,
     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.  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 nonzero
     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, eliminating duplicates.

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

     #define TABSIZE 50
     #define ELSIZE 120

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

SEE ALSO
     cc(1), 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.

     Both functions return NULL in case of error.

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.

     To be compatible with traditional C usage, make lsearch and lfind return
     type pointer-to-character by compiling your program with the

          -A nansi

     option (see cc(1)) and inserting the directive

          #define _CLASSIC_TYPES

     before any #include directives.  In this case, 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.