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lsearch(3)						     Library Functions Manual							lsearch(3)

Name
       lsearch, lfind - linear search and update

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

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

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

Description
       The  subroutine	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.  The key points to the datum to be sought in the ta-
       ble.   The  base  points to the first element in the table.  The nelp points to an integer containing the current number of elements in the
       table.  The width is the size of an element in bytes.  The integer is incremented if the datum is added to the table.  The  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 ele-
       ments being compared.  The function must return zero if the elements are equal and non-zero otherwise.

       The subroutine 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.  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.

       Although declared as type pointer-to-character, the value returned should be cast into type pointer-to-element.

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

Return Values
       If the searched for datum is found, both and return a pointer to it.  Otherwise, returns NULL and returns a pointer to the newly added ele-
       ment.

See Also
       bsearch(3), hsearch(3), tsearch(3)

																	lsearch(3)

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lsearch(3C)						   Standard C Library Functions 					       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
The lsearch() function is a linear search routine generalized from Knuth (6.1) Algorithm S. (see The Art of Computer Programming, Volume 3, Section 6.1, by Donald E. Knuth.). It returns a pointer to a table indicating where a datum can be found. If the datum does not occur, it is added at the end of the table. The key argument points to the datum to be sought in the table. The base argument points to the first element in the table. The nelp argument points to an integer containing the current number of elements in the table. The integer is incre- mented if the datum is added to the table. The width argument is the size of an element in bytes. The compar argument is a pointer to the comparison function that the user must supply (strcmp(3C) 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. The lfind() function 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. It is important to note the following: o The pointers to the key and the element at the base of the table can be pointers to any type. o The comparison function need not compare every byte, so arbitrary data can be contained in the elements in addition to the val- ues being compared. o The value returned should be cast into type pointer-to-element. RETURN VALUES
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. USAGE
Undefined results can occur if there is not enough room in the table to add a new item. The lsearch() and lfind() functions safely allows concurrent access by multiple threads to disjoint data, such as overlapping subtrees or tables. EXAMPLES
Example 1 A sample code using the lsearch() function. This program will read in less than TABSIZE strings of length less than ELSIZE and store them in a table, eliminating duplicates, and then will print each entry. #include <search.h> #include <string.h> #include <stdlib.h> #include <stdio.h> #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; } ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
bsearch(3C), hsearch(3C), string(3C), tsearch(3C), attributes(5), standards(5) The Art of Computer Programming, Volume 3, Sorting and Searching by Donald E. Knuth, published by Addison-Wesley Publishing Company, 1973. SunOS 5.11 6 Dec 2004 lsearch(3C)
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