lsearch, lfind - linear search and update
void *lsearch (key, base, nelp, width, compar)
int (*compar)( );
void *lfind (key, base, nelp, width, compar)
int (*compar)( );
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 elements
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-
The comparison function need not compare every byte, so arbitrary data
may be contained in the elements in addition to the values being com‐
Although declared as type pointer-to-character, the value returned
should be cast into type pointer-to-element.
Undefined results can occur if there is not enough room in the table to
add a new item.
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‐
See Alsobsearch(3), hsearch(3), tsearch(3)lsearch(3)