Libdict is a compact, ANSI C library which provides access to a set of
generic and flexible ``dictionary'' data structures. All algorithms
used in libdict have been optimized, and, with one very small exception,
are not recursive but iterative. It was written by Farooq Mela, and is
released under a BSD style licence.

Libdict implements the following data structures: AVL Tree, Red-Black
Tree, Splay Tree, Treap, Weight-balanced tree, Path-reduction tree,
Hashtable (Chained).

These structures can be used to efficiently store and retrieve key-data
pairs. Each of these structures can be accessed using its direct API, or
it can be accessed using a dictionary abstraction.  Despite it's name,
libdict can be used to store any kind of data and any kind of key (provided
it fits into a 'void' pointer on your system).

WWW: http://www.crazycoder.org/libdict.html