NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

     #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    [Toc]    [Back]

     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
traversal
     type, and a node level (where level zero is the root of  the
tree).

RETURN VALUES    [Toc]    [Back]

     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    [Toc]    [Back]

     bsearch(3), lsearch(3)

OpenBSD      3.6                           June      15,     1997