Doxygen

Developer(s) Dimitri van Heesch 26 October 1997; 17 years ago[1] 1.8.9.1 / 4 January 2015; 4 months ago C++ Cross-platform Documentation generator GNU General Public License doxygen.org

Doxygen [2] is a documentation generator, a tool for writing software reference documentation. The documentation is written within code, and is thus relatively easy to keep up to date. Doxygen can cross reference documentation and code, so that the reader of a document can easily refer to the actual code.

Doxygen supports multiple programming languages, in particular C++, C, C#, Objective-C, Java, Perl,[3] Python, IDL, VHDL, Fortran, Tcl and PHP.[4] Doxygen is free software, released under the terms of the GNU General Public License.

Design

Like Javadoc, Doxygen extracts documentation from source file comments. In addition to the Javadoc syntax, Doxygen supports the documentation tags used in the Qt toolkit and can generate output in HyperText Markup Language (HTML) as well as in Microsoft Compiled HTML Help (CHM), Rich Text Format (RTF), Portable Document Format (PDF), LaTeX, PostScript or man pages.

Uses

Doxygen can be used with C, C++, C#, Fortran, Java, Objective-C, PHP, Python, Tcl IDL (CORBA, and Microsoft flavors), VHDL, and to some extent D.

It runs on most Unix-like systems, Mac OS X and Windows.

The first version of Doxygen borrowed code from an early version of DOC++ (developed by Roland Wunderling and Malte Zöckler at Zuse Institute Berlin); later, the Doxygen code was rewritten by Dimitri van Heesch.

Example code

A screenshot of what the output would look like in HTML

The generic syntax of documentation comments is to start a comment with an extra asterisk after the leading comment delimiter '/*':

/**
<A short one line description>

<Longer description>
<May span multiple lines or paragraphs as needed>

@param  Description of method's or function's input parameter
@param  ...
@return Description of the return value
*/


Many programmers like to mark the start of each line with space-asterisk-space, as follows, but that is not necessary.

/**
* <A short one line description>
*
* <Longer description>
* <May span multiple lines or paragraphs as needed>
*
* @param  Description of method's or function's input parameter
* @param  ...
* @return Description of the return value
*/


/// <A short one line description>
///
/// <Longer description>
/// <May span multiple lines or paragraphs as needed>
///
/// @param  Description of method's or function's input parameter
/// @param  ...
/// @return Description of the return value


The following illustrates how a C++ source file can be documented.

/**
* @file
* @author  John Doe <jdoe@example.com>
* @version 1.0
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details at
* https://www.gnu.org/copyleft/gpl.html
*
* @section DESCRIPTION
*
* The time class represents a moment of time.
*/

class Time {

public:

/**
* Constructor that sets the time to a given value.
*
* @param timemillis Number of milliseconds
*        passed since Jan 1, 1970.
*/
Time (int timemillis) {
// the code
}

/**
* Get the current time.
*
* @return A time object set to the current time.
*/
static Time now () {
// the code
}
};


An alternative approach for documenting parameters is shown below. It will produce the same documentation.

       /**
* Constructor that sets the time to a given value.
*/
Time (int timemillis ///< Number of milliseconds passed since Jan 1, 1970.>
)
{
// the code
}


Richer markup is also possible. For instance, add equations using LaTeX commands:

/**
*
* An inline equation @f$e^{\pi i}+1 = 0 @f$
*
* A displayed equation: @f[ e^{\pi i}+1 = 0 @f]
*
*/