1. Introduction

A question which frequently arises among Unix C++ programmers is how to load C++ functions and classes dynamically using the dlopen API.

In fact, that is not always simple and needs some explanation. That's what this mini HOWTO does.

An average understanding of the C and C++ programming language and of the dlopen API is necessary to understand this document.

This HOWTO's master location is http://www.isotton.com/howtos/C++-dlopen-mini-HOWTO/.

1.1. Copyright and License

This document, C++ dlopen mini HOWTO, is copyrighted (c) 2002-2006 by Aaron Isotton. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 2, as published by the Free Software Foundation.

1.2. Disclaimer

No liability for the contents of this document can be accepted. Use the concepts, examples and information at your own risk. There may be errors and inaccuracies, that could be damaging to your system. Proceed with caution, and although this is highly unlikely, the author(s) do not take any responsibility.

All copyrights are held by their by their respective owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark. Naming of particular products or brands should not be seen as endorsements.

1.3. Credits / Contributors

In this document, I have the pleasure of acknowledging (in alphabetic order):

  • Joy Y Goodreau for her editing.

  • D. Stimitis for pointing out a few issues with the formatting and the name mangling, as well as pointing out a few subtleties of extern "C".

    Many unnamed others pointing out errors or giving tips to improve this howto. You know who you are!

1.4. Feedback

Feedback is most certainly welcome for this document. Send your additions, comments and criticisms to the following email address: .

1.5. Terms Used in this Document

dlopen API

The dlclose, dlerror, dlopen and dlsym functions as described in the dlopen(3) man page.

Notice that we use dlopen to refer to the individual dlopen function, and dlopen API to refer to the entire API.