lsearch.3c (2010 09)

l
lsearch(3C) lsearch(3C)
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
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 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() 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.
The comparison function need not compare every byte, so arbitrary data may be contained in the ele-
ments 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.
EXAMPLES
This code fragment reads in ≤ TABSIZE strings of length ≤ ELSIZE and stores them in a table, elim-
inating duplicates.
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