lsearch(3) [freebsd man page]

LSEARCH(3)						   BSD Library Functions Manual 						LSEARCH(3)

NAME

     lsearch, lfind -- linear search and append

LIBRARY

     Standard C Library (libc, -lc)

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() and lfind() functions walk linearly through an array and compare each element with the one to be sought using a supplied com-
     parison function.

     The key argument points to an element that matches the one that is searched.  The array's address in memory is denoted by the base argument.
     The width of one element (i.e., the size as returned by sizeof()) is passed as the width argument.  The number of valid elements contained in
     the array (not the number of elements the array has space reserved for) is given in the integer pointed to by nelp.  The compar argument
     points to a function which compares its two arguments and returns zero if they are matching, and non-zero otherwise.

     If no matching element was found in the array, lsearch() copies key into the position after the last element and increments the integer
     pointed to by nelp.

RETURN VALUES

     The lsearch() and lfind() functions return a pointer to the first element found.  If no element was found, lsearch() returns a pointer to the
     newly added element, whereas lfind() returns NULL.  Both functions return NULL if an error occurs.

EXAMPLES

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

     static int
     element_compare(const void *p1, const void *p2)
     {
	     int left = *(const int *)p1;
	     int right = *(const int *)p2;

	     return (left - right);
     }

     int
     main(int argc, char **argv)
     {
	     const int array[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
	     size_t element_size = sizeof(array[0]);
	     size_t array_size = sizeof(array) / element_size;
	     int key;
	     void *element;

	     printf("Enter a number: ");
	     if (scanf("%d", &key) != 1) {
		     printf("Bad input0);
		     return (EXIT_FAILURE);
	     }

	     element = lfind(&key, array, &array_size, element_size,
		 element_compare);

	     if (element != NULL)
		     printf("Element found: %d0, *(int *)element);
	     else
		     printf("Element not found0);

	     return (EXIT_SUCCESS);
     }

SEE ALSO

     bsearch(3), hsearch(3), tsearch(3)

STANDARDS

     The lsearch() and lfind() functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').

HISTORY

     The lsearch() and lfind() functions appeared in 4.2BSD.  In FreeBSD 5.0, they reappeared conforming to IEEE Std 1003.1-2001 (``POSIX.1'').

BSD
								  April 21, 2013							       BSD

Check Out this Related Man Page

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)

Linux and UNIX Man Pages

lsearch(3) [freebsd man page]

Check Out this Related Man Page