CLucene is a high-performance, scalable, cross platform, full-featured, open-source indexing and searching API. It is written in C++.
CLucene is a port of the very popular Java Lucene text search engine API. Specifically, CLucene is the guts of a search engine, the hard stuff. You write the easy stuff, the UI and the process of selecting and parsing your data files to pump them into the search engine yourself.
CLucene Search Engine Homepage
CLucene Search Engine @ SourceForge
CLucene Search Engine Download