LSEARCH(3C-SVR4)    RISC/os Reference Manual     LSEARCH(3C-SVR4)



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 indi-
     cating 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 con-
     taining 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 other-
     wise.

     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, eliminat-
     ing 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-SVR4)    RISC/os Reference Manual     LSEARCH(3C-SVR4)



          #define TABSIZE 50
          #define ELSIZE 120

          main()
          {
               char line[ELSIZE];  /* buffer to hold input string */
               char tab[TABSIZE][ELSIZE];    /* table of strings */
               size_t 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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