A Recursively-Defined Tree Class¹

Jeffrey D. Oldham

2000 Apr 05

We explain how to use the recursively defined Tree class. The implementation file and example use code are available.

The Tree Class

Using the templatized Tree class requires specifying the type of the items stored in the tree. In this document, we will use trees of ints.

A tree is

• either an empty tree
• or an item with two subtrees.

Empty Trees

To create an empty tree, use

Tree<int>()

To check if a tree T is empty, use

T.empty()

which returns the boolean value true if the tree has no items and otherwise false. Using T in a place where a boolean is expected yields true if the tree is not empty and otherwise false. For example, if (T) cout << "tree is not empty $\backslash$n";.

Nonempty Trees

To construct a tree with one item, e.g., 3, use

Tree<int>(3,Tree<int>(),Tree<int>())

To construct a tree with one item, e.g., -17, and two tree children L and R, use

Tree<int>(-17,L,R)

To obtain a tree T's item, which has int type, use

T.item()

To obtain the left subtree, which has Tree<int> type, use

T.left()

To obtain the right subtree, which has Tree<int> type, use

T.right()

To check if a tree is nonempty, negate the result of checking for an empty tree.

Example

The example use code illustrates using Trees.

Logistics of Using the Code

To use the linked tree class with a program you wrote, copy the implementation file to the directory containing the program's C++ code. One way to do this is to use the ``Save As...'' item on a WWW browser's file menu.

In your C++ program, add the line

#include "tree.h"

near the other header inclusions. See also the sample program.

Footnotes

... Class¹

©2000 Jeffrey D. Oldham . All rights reserved. This document may not be redistributed in any form without the express permission of the author.