lsearch(3C)          COMPATIBILITY FUNCTIONS          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 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>



          Last change: C Programming Language Utilities         1

lsearch(3C)          COMPATIBILITY FUNCTIONS          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.



























          Last change: C Programming Language Utilities         2