in-order traversal


Definition: Process all nodes of a tree by recursively processing the left subtree, then processing the root, and finally the right subtree.

Also known as symmetric traversal.

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

Aggregate parent (I am a part of or used in ...)
treesort (1).

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

Note: For instance, if the "processing" is just printing, a tree is printed as "(left subtree) root (right 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.

If you have suggestions, corrections, or comments, please get in touch with Paul Black.

Entry modified 3 May 2019.
HTML page formatted Fri May 3 16:28:23 2019.

Cite this as:
Paul E. Black, "in-order traversal", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 3 May 2019. (accessed TODAY) Available from: