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 lsearch 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 table. 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 elements being compared. The function must return zero if the elements are equal and non-zero otherwise.
The lfind 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.
Note
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 lsearch and lfind return a pointer to it. Otherwise, lfind returns NULL and lsearch returns a pointer to the newly added element.