The rxstring library is an extension of the C++ stdlib string class. The rxstring class is a powerful alternative to traditional regular expression libraries. Because the syntax used by traditional regular expression packages is difficult to learn, rxstring uses a alternative notational system that is much easier to learn to read and write. Because indirection is a fundamental programming technique, rxstring regular expressions can be nested within each other using labels. Also the regular expressions can be self referential, this makes it possible to write very powerful regular expressions that can validate input just as a recursive descent parser does, but without the hassle of hand coding or resorting to a tool like yacc or bison. rxstring has much more than the usual search and match functions, There are a large number of functions that aid in validating, parsing, and modifying text. In spite of the number of functions, there is an underlying system that makes it easy to recall the entire library off the top of your head without much effort.