1.\" $NetBSD: tsearch.3,v 1.3 2002/02/07 07:00:30 ross Exp $ 2.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 3. The name of the author may not be used to endorse or promote products 14.\" derived from this software without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 17.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 18.\" AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 19.\" THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 20.\" EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21.\" PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22.\" OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24.\" OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25.\" ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" OpenBSD: tsearch.3,v 1.2 1998/06/21 22:13:49 millert Exp 28.\" 29.Dd June 15, 1997 30.Dt TSEARCH 3 31.Os 32.Sh NAME 33.Nm tsearch, tfind, tdelete, twalk 34.Nd manipulate binary search trees 35.Sh SYNOPSIS 36.Fd #include \*[Lt]search.h\*[Gt] 37.Ft void * 38.Fn tdelete "const void *key" "void **rootp", "int (*compar) (const void *, const void *)" 39.Ft void * 40.Fn tfind "const void *key" "const void **rootp", "int (*compar) (const void *, const void *)" 41.Ft void * 42.Fn tsearch "const void *key" "void **rootp", "int (*compar) (const void *, const void *)" 43.Ft void 44.Fn twalk "const void *root" "void (*compar) (const void *, VISIT, int)" 45.Sh DESCRIPTION 46The 47.Fn tdelete , 48.Fn tfind , 49.Fn tsearch , 50and 51.Fn twalk 52functions manage binary search trees based on algorithms T and D 53from Knuth (6.2.2). The comparison function passed in by 54the user has the same style of return values as 55.Xr strcmp 3 . 56.Pp 57.Fn Tfind 58searches for the datum matched by the argument 59.Fa key 60in the binary tree rooted at 61.Fa rootp , 62returning a pointer to the datum if it is found and NULL 63if it is not. 64.Pp 65.Fn Tsearch 66is identical to 67.Fn tfind 68except that if no match is found, 69.Fa key 70is inserted into the tree and a pointer to it is returned. If 71.Fa rootp 72points to a NULL value a new binary search tree is created. 73.Pp 74.Fn Tdelete 75deletes a node from the specified binary search tree and returns 76a pointer to the parent of the node to be deleted. 77It takes the same arguments as 78.Fn tfind 79and 80.Fn tsearch . 81If the node to be deleted is the root of the binary search tree, 82.Fa rootp 83will be adjusted. 84.Pp 85.Fn Twalk 86walks the binary search tree rooted in 87.fa root 88and calls the function 89.Fa action 90on each node. 91.Fa Action 92is called with three arguments: a pointer to the current node, 93a value from the enum 94.Sy "typedef enum { preorder, postorder, endorder, leaf } VISIT;" 95specifying the traversal type, and a node level (where level 96zero is the root of the tree). 97.Sh RETURN VALUES 98The 99.Fn tsearch 100function returns NULL if allocation of a new node fails (usually 101due to a lack of free memory). 102.Pp 103.Fn Tfind , 104.Fn tsearch , 105and 106.Fn tdelete 107return NULL if 108.Fa rootp 109is NULL or the datum cannot be found. 110.Pp 111The 112.Fn twalk 113function returns no value. 114.Sh SEE ALSO 115.Xr bsearch 3 , 116.Xr hsearch 3 , 117.Xr lsearch 3 118