TSEARCH(3) | Library Functions Manual | TSEARCH(3) |
tsearch, tfind, tdelete, twalk
—
#include <search.h>
void *
tdelete
(const
void * restrict key, void
** restrict rootp, int
(*compar) (const void *, const void *));
void *
tfind
(const
void *key, const void *
const *rootp, int
(*compar) (const void *, const void *));
void *
tsearch
(const
void *key, void
**rootp, int (*compar)
(const void *, const void *));
void
twalk
(const
void *root, void
(*action) (const void *, VISIT, int));
tdelete
(), tfind
(),
tsearch
(), and twalk
()
functions manage binary search trees based on algorithms T and D from Knuth
(6.2.2). The comparison function passed in by the user has the same style of
return values as strcmp(3).
tfind
() searches for the datum matched by
the argument key in the binary tree rooted at
rootp, returning a pointer to the datum if it is found
and NULL if it is not.
tsearch
() is identical to
tfind
() except that if no match is found,
key is inserted into the tree and a pointer to it is
returned. If rootp points to a NULL value a new binary
search tree is created.
tdelete
() deletes a node from the
specified binary search tree and returns a pointer to the parent of the node
to be deleted. It takes the same arguments as
tfind
() and tsearch
(). If
the node to be deleted is the root of the binary search tree,
rootp will be adjusted.
twalk
() walks the binary search tree
rooted in root and calls the function
action on each node. Action is
called with three arguments: a pointer to the current node, a value from the
enum typedef enum { preorder, postorder, endorder, leaf }
VISIT; specifying the traversal type, and a node level (where level zero
is the root of the tree).
tsearch
() function returns NULL if allocation of a
new node fails (usually due to a lack of free memory).
tfind
(),
tsearch
(), and tdelete
()
return NULL if rootp is NULL or the datum cannot be
found.
The twalk
() function returns no value.
tdelete
()
should not rely on any specific behaviour. The IEEE Std
1003.1-2008 (“POSIX.1”) revision tried to clarify the
issue with the following wording: “the
tdelete
() function shall return a pointer to the
parent of the deleted node, or an unspecified non-NULL pointer if the deleted
node was the root node, or a NULL
pointer if the node
is not found”.
April 30, 2010 | NetBSD 9.0 |