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Introduction

Doxygen is the de facto standard tool for generating documentation from annotated C++ sources, but it also supports other popular programming languages such as C, Objective-C, C#, PHP, Java, Python, IDL (Corba, Microsoft, and UNO/OpenOffice flavors), Fortran, VHDL, Tcl, and to some extent D.

Doxygen can help you in three ways:

It can generate an on-line documentation browser (in HTML) and/or an off-line reference manual (in $\mbox{\LaTeX}$ ) from a set of documented source files. There is also support for generating output in RTF (MS-Word), PostScript, hyperlinked PDF, compressed HTML, and Unix man pages. The documentation is extracted directly from the sources, which makes it much easier to keep the documentation consistent with the source code.
You can configure doxygen to extract the code structure from undocumented source files. This is very useful to quickly find your way in large source distributions. Doxygen can also visualize the relations between the various elements by means of include dependency graphs, inheritance diagrams, and collaboration diagrams, which are all generated automatically.
You can also use doxygen for creating normal documentation (as I did for the doxygen user manual and web-site).

Doxygen is developed under Mac OS X and Linux, but is set-up to be highly portable. As a result, it runs on most other Unix flavors as well. Furthermore, executables for Windows are available.

This manual is divided into three parts, each of which is divided into several sections.

The first part forms a user manual:

Section Installation discusses how to download, compile and install doxygen for your platform.
Section Getting started tells you how to generate your first piece of documentation quickly.
Section Documenting the code demonstrates the various ways that code can be documented.
Section Markdown support show the Markdown formatting supported by doxygen.
Section Lists shows how to create lists.
Section Grouping shows how to group things together.
Section Including formulas shows how to insert formulas in the documentation.
Section Graphs and diagrams describes the diagrams and graphs that doxygen can generate.
Section Preprocessing explains how doxygen deals with macro definitions.
Section Automatic link generation shows how to put links to files, classes, and members in the documentation.
Section Output Formats shows how to generate the various output formats supported by doxygen.
Section Searching shows various ways to search in the HTML documentation.
Section External Indexing and Searching shows how use the external search and index tools
Section Customizing the output explains how you can customize the output generated by doxygen.
Section Custom Commands show how to define and use custom commands in your comments.
Section Linking to external documentation explains how to let doxygen create links to externally generated documentation.
Section Frequently Asked Questions gives answers to frequently asked questions.
Section Troubleshooting tells you what to do when you have problems.

The second part forms a reference manual:

Section Features presents an overview of what doxygen can do.
Section Doxygen usage shows how to use the doxygen program.
Section Doxywizard usage shows how to use the doxywizard program.
Section Configuration shows how to fine-tune doxygen, so it generates the documentation you want.
Section Special Commands shows an overview of the special commands that can be used within the documentation.
Section HTML Commands shows an overview of the HTML commands that can be used within the documentation.
Section XML Commands shows an overview of the C# style XML commands that can be used within the documentation.

The third part provides information for developers:

Section Doxygen's Internals gives a global overview of how doxygen is internally structured.
Section Perl Module Output shows how to use the PerlMod output.
Section Internationalization explains how to add support for new output languages.

Doxygen license

Permission to use, copy, modify, and distribute this software and its documentation under the terms of the GNU General Public License is hereby granted. No representations are made about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. See the GNU General Public License for more details.

Documents produced by doxygen are derivative works derived from the input used in their production; they are not affected by this license.

User examples

Doxygen supports a number of output formats where HTML is the most popular one. I've gathered some nice examples of real-life projects using doxygen.

These are part of a larger list of projects that use doxygen. If you know other projects, let me know and I'll add them.

Future work

Although doxygen is successfully used by large number of companies and open source projects already, there is always room for improvement.

You can submit enhancement requests in the bug tracker. Make sure the severity of the bug report is set to "enhancement".

Acknowledgments

Thanks go to:

Malte Zöckler and Roland Wunderling, authors of DOC++. The first version of doxygen borrowed some code of an old version of DOC++. Although I have rewritten practically all code since then, DOC++ has still given me a good start in writing doxygen.
All people at Qt Software, for creating a beautiful GUI Toolkit (which is very useful as a Windows/Unix platform abstraction layer :-)
My brother Frank for rendering the logos.
Harm van der Heijden for adding HTML help support.
Wouter Slegers of Your Creative Solutions for registering the www.doxygen.org domain.
Parker Waechter for adding the RTF output generator.
Joerg Baumann, for adding conditional documentation blocks, PDF links, and the configuration generator.
Tim Mensch for adding the todo command.
Christian Hammond for redesigning the web-site.
Ken Wong for providing the HTML tree view code.
Talin for adding support for C# style comments with XML markup.
Petr Prikryl for coordinating the internationalization support. All language maintainers for providing translations into many languages.
The band Porcupine Tree for providing hours of great music to listen to while coding.
many, many others for suggestions, patches and bug reports.

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