from
The Free On-line Dictionary of Computing (8 July 2008)
traversal
in-order traversal
post-order traversal
pre-order traversal
traverse
<data> Processing {nodes} in a {graph} one at a time, usually
in some specified order. Traversal of a tree is {recursive}ly
defined to mean visiting the {root node} and traversing its
children. Visiting a node usually involves transforming it in
some way or collecting data from it.
In "pre-order traversal", a node is visited __before__ its
children. In "post-order" traversal, a node is visited
__after__ its children. The more rarely used "in-order"
traversal is generally applicable only to binary trees, and is
where you visit first a node's left child, then the node
itself, and then its right child.
For the binary tree:
T
/ \
I S
/ \
D E
A pre-order traversal visits the nodes in the order T I D E S.
A post-order traversal visits them in the order D E I S T. An
in-order traversal visits them in the order D I E T S.
(2001-10-01)