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NAME

       lsearch, lfind - linear search and update

SYNOPSIS

       #include <search.h>

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

DESCRIPTION

       The  lsearch()  function  shall  linearly search the table and return a
       pointer into the table for the matching entry. If the  entry  does  not
       occur,  it  shall  be  added  at the end of the table. The key argument
       points to the entry to be sought in the table. The base argument points
       to the first element in the table. The width argument is the size of an
       element in bytes. The nelp argument points to an integer containing the
       current  number  of  elements  in  the table. The integer to which nelp
       points shall be incremented if the entry is added  to  the  table.  The
       compar  argument  points to a comparison function which the application
       shall supply (for example, strcmp()).  It is called with two  arguments
       that point to the elements being compared. The application shall ensure
       that the function returns 0 if the elements  are  equal,  and  non-zero
       otherwise.

       The  lfind()  function shall be equivalent to lsearch(), except that if
       the entry is not found, it is not added to the table. Instead,  a  null
       pointer is returned.

RETURN VALUE

       If  the  searched  for entry is found, both lsearch() and lfind() shall
       return a pointer to it. Otherwise, lfind() shall return a null  pointer
       and lsearch() shall return a pointer to the newly added element.

       Both functions shall return a null pointer in case of error.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

   Storing Strings in a Table
       This  fragment reads in less than or equal to TABSIZE strings of length
       less than or equal to ELSIZE and stores them in  a  table,  eliminating
       duplicates.

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

              #define TABSIZE 50
              #define ELSIZE 120

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

   Finding a Matching Entry
       The following example finds any line that reads "This is a test."  .

              #include <search.h>
              #include <string.h>
              ...
              char line[ELSIZE], tab[TABSIZE][ELSIZE];
              size_t nel = 0;
              char *findline;
              void *entry;

              findline = "This is a test.\n";

              entry = lfind(findline, tab, &nel, ELSIZE, (
                  int (*)(const void *, const void *)) strcmp);

APPLICATION USAGE

       The  comparison function need not compare every byte, so arbitrary data
       may be contained in the  elements  in  addition  to  the  values  being
       compared.

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

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       hcreate()   ,   tsearch()   ,   the   Base   Definitions   volume    of
       IEEE Std 1003.1-2001, <search.h>

COPYRIGHT

       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE and
       The  Open Group Standard, the original IEEE and The Open Group Standard
       is the referee document. The original Standard can be  obtained  online
       at http://www.opengroup.org/unix/online.html .