Shulou(Shulou.com)06/03 Report--

This article mainly introduces "how to use Perl to parse files". In daily operation, I believe many people have doubts about how to use Perl to parse files. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "how to use Perl to parse files". Next, please follow the editor to study!

Parsing XML Files with Perl

When using XML in Perl, you have nearly five hundred CPAN modules to choose from, each of which supports the integration of different aspects of Web services. In addition, the core library of Perl includes several modules that support XML. This article focuses on one of the earliest and most frequently involved core modules: XML::Parser.

XML:: parser series

The original Perl parser, XML::Parser::Expat, was written by LarryWall a few years ago and continued by ClarkCooper. As the interface of ExpatXMLparser, the module is written by JamesClark in C language and has been adopted by some scripting languages.

Perl parses the Expat in the XML file as an event-based parser, meaning that specific conditions trigger processing. For example, a start or end tag will trigger the appropriate user-defined subroutine. XML::Parser module is constructed for common applications on the basis of Expat function.

Note that Expat does not validate XML before parsing and invalidates when errors are encountered. These limitations will make the XML::Parser module very fast.

Introduction to XML::Parser

Anyone can write a XML parser in Perl. After all, you are only dealing with text in a known format. But because the XML::Parser module is written in C, it is much more efficient than any pure Perl application you can implement. And now that it has been written, you can spend your time on other more useful things.

The Expat function of XML::Parser allows you to define the style of the parser you use. The most commonly used styles are Tree and Stream,Tree to handle XML input, creating a set of arrays containing the elements and data in the file, so that you can control the structure as you wish. Stream will analyze the behavior at a hierarchical level and handle it at the beginning of an event. To use Stream, you must define a handler when you instantiate a module and associate it with a subroutine that describes how to handle an event when it occurs.

Other styles include: Sub, which allows you to define the function of a XML tag specifically. Debug, which displays the file with non-standard output. Object, similar to Tree but returns an object. You can also set a custom style by defining a subclass in the XML::Parser class.

At this point, the study on "how to use Perl to parse files" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.