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.\" $NetBSD$

.\" Copyright (c) 1997 Todd C. Miller 

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.\"     OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp

.\" $FreeBSD: src/lib/libc/stdlib/tsearch.3,v 1.7 2001/09/07 14:46:36 asmodai Exp $

.\"

.Dd June 15, 1997

.Dt TSEARCH 3

.Os

.Sh NAME

.Nm tsearch , tfind , tdelete , twalk

.Nd manipulate binary search trees

.Sh SYNOPSIS

.In search.h

.Ft void *

.Fn tdelete "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"

.Ft void *

.Fn tfind "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"

.Ft void *

.Fn tsearch "const void *key" "void **rootp" "int (*compar) (const void *, const void *)"

.Ft void

.Fn twalk "const void *root" "void (*compar) (const void *, VISIT, int)"

.Sh DESCRIPTION

The

.Fn tdelete ,

.Fn tfind ,

.Fn tsearch ,

and

.Fn 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

.Xr strcmp 3 .

.Pp

.Fn Tfind

searches for the datum matched by the argument

.Fa key

in the binary tree rooted at

.Fa rootp ,

returning a pointer to the datum if it is found and NULL

if it is not.

.Pp

.Fn Tsearch

is identical to

.Fn tfind

except that if no match is found,

.Fa key

is inserted into the tree and a pointer to it is returned.  If

.Fa rootp

points to a NULL value a new binary search tree is created.

.Pp

.Fn 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

.Fn tfind

and

.Fn tsearch .

If the node to be deleted is the root of the binary search tree,

.Fa rootp

will be adjusted.

.Pp

.Fn Twalk

walks the binary search tree rooted in

.Fa root

and calls the function

.Fa action

on each node.

.Fa Action

is called with three arguments: a pointer to the current node,

a value from the enum

.Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;"

specifying the traversal type, and a node level (where level

zero is the root of the tree).

.Sh SEE ALSO

.Xr bsearch 3 ,

.Xr hsearch 3 ,

.Xr lsearch 3

.Sh RETURN VALUES

The

.Fn tsearch

function returns NULL if allocation of a new node fails (usually

due to a lack of free memory).

.Pp

.Fn Tfind ,

.Fn tsearch ,

and

.Fn tdelete

return NULL if

.Fa rootp

is NULL or the datum cannot be found.

.Pp

The

.Fn twalk

function returns no value.