More Than Equations

A Tree Made of Files

3 min read

🔖 Background Information

The tree command is a utility that prints out the structure of files and folders starting from a given folder (robinharwood et al., 2023). For example, if I use the tree command from some folder on my disk, I might see the following:

$ tree path/to/folder/
 
path/to/folder/
├── some-file.txt
├── another-file.txt
├── subfolder
│   ├── my-code.cpp
│   └── my-code.h
└── last-file.txt
 
1 directories, 5 files

The tree command treats the files and folders on your disk as a tree data structure. The name of the command makes sense!

A robust implementation of tree can be a bit complicated, but a GitHub user named Kevin Newton implements a simplified version of tree whenever they want to learn a new programming language (Newton, 2025). We will analyze and expand upon their code in this lab.

🎯 Problem Statement

Complete the following tasks:

  1. Read through the C++ or Java implementation of the tree function as written by Newton in their tree repository (Newton, 2025).
  2. Make sure that you can run Newton’s original code locally on your computer.
  3. Update the implementation of tree to list the directories / files in reverse alphabetical order.

✅ Acceptance Criteria

  • The tree function should work in exactly the same way as before. However, the output should be different.
  • Child directories should be listed in reverse alphabetical order.
  • Files within each directory should be listed in reverse alphabetical order.

📋 Dev Notes

N/A

🖥️ Example Output

Suppose the original tree function listed files and directories like so:

$ ./tree.out
 
.
|- folder_a/
|---- file_a.txt
|---- file_b.txt
|---- file_c.txt
|- folder_b/
|---- file_a.txt
|---- file_b.txt
|---- file_c.txt

I now expect to see the following output:

$ ./tree.out
 
.
|- folder_b/
|---- file_c.txt
|---- file_b.txt
|---- file_a.txt
|- folder_a/
|---- file_c.txt
|---- file_b.txt
|---- file_a.txt

📝 Thought Provoking Questions

  1. How does the command work? Give a high-level description of how the command displays a tree in the console.
  2. Is the filesystem displayed by the tree command an example of a binary tree or a general tree?
  3. What is the root node of the tree displayed by the tree command?
  4. What are the leaf nodes of the tree displayed by the tree command?
  5. How might you generate a tree with the largest possible depth via the tree command on a given filesystem?

💼 Add-Ons For the Portfolio

N/A

🔗 Useful Links

📘 Works Cited

Newton, K. (2025). Kddnewton/Tree. https://github.com/kddnewton/tree
robinharwood, Saisang, Xelu86, eross-msft, john-par, coreyp-at-msft, b-r-o-c-k, & lizap. (2023). Tree. In Windows Server - Learn. https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/tree

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