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NetBSD 6.1.5 - man page for tfind (netbsd section 3)

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TSEARCH(3)			   BSD Library Functions Manual 		       TSEARCH(3)

NAME
     tsearch, tfind, tdelete, twalk -- manipulate binary search trees

SYNOPSIS
     #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));

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.

     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 traver-
     sal 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 ALSO
     bsearch(3), hsearch(3), lsearch(3)

STANDARDS
     These functions conform to IEEE Std 1003.1-2001 (``POSIX.1'').

CAVEATS
     The IEEE Std 1003.1-2001 (``POSIX.1'') standard does not specify what value should be
     returned when deleting the root node.  Since implementations vary, user of 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''.

BSD					  April 30, 2010				      BSD
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