preorder traversal


Definition: Process all nodes of a tree by processing the root, then recursively processing all subtrees.

Also known as prefix traversal.

Generalization (I am a kind of ...)
tree traversal, depth-first search.

See also in-order traversal, postorder traversal, level-order traversal, Cupif-Giannini tree traversal.

Note: For instance, if the "processing" is just printing, a tree is printed as "root (first subtree) (second subtree) ... (last subtree)". Here is pseudocode for a binary tree:

if tree is null, return;


Author: PEB

Go to the Dictionary of Algorithms and Data Structures home page.

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Entry modified 22 April 2019.
HTML page formatted Mon Apr 22 12:17:39 2019.

Cite this as:
Paul E. Black, "preorder traversal", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 22 April 2019. (accessed TODAY) Available from: