The c prototyping tools library provides generic tools for application development in plain c covering basic data structure implementations, persistence, threading and tcp and http communication. lgpl
Why another XML library? Because it is fast, easy-to-use and -important- it is my personal work about the second layer of the Semantic Web. LGPL 2.0 license
The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. PCRE has its own native API, as well as a set of wrapper functions that correspond to the POSIX regular expression API.