Regex

Regex: searches for and matches text strings

A regular expression (or regexp, or pattern) is a text string that describes some set of strings. Using the Regex library, you can: •see if a string matches a specified pattern as a whole, and •search within a string for a substring matching a specified pattern. Regex provides three groups of functions with which you can operate on regular expressions. One group--the GNU group--is more powerful but not completely compatible with the other two, namely the POSIX and Berkeley UNIX groups; its interface was designed specifically for GNU. The other groups have the same interfaces as do the regular expression functions in POSIX and Berkeley UNIX. http://www.gnu.org/directory/regex.html