TSEARCH(3) OpenBSD Programmer's Manual TSEARCH(3)NAME
tsearch, tfind, tdelete, twalk - manipulate binary search trees
SYNOPSIS
#include <search.h>
void *
tdelete(const void *key, void **rootp, int (*compar) (const void *, const
void *));
void *
tfind(const void *key, 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));
DESCRIPTION
The 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 and a pointer
to the new root will be returned.
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).
RETURN VALUES
The 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.
SEE ALSObsearch(3), lsearch(3)STANDARDS
These functions conform to IEEE Std 1003.1-2004 (``POSIX'').
CAVEATS
The IEEE Std 1003.1-2004 (``POSIX'') standard does not specify what value
should be returned when deleting the root node. Since implementations
vary, the user of the tdelete() function should not rely on a specific
behaviour.
OpenBSD 4.9 May 31, 2007 OpenBSD 4.9
