XMLin() and XMLout() Methods

Perl Tutorials - Herong's Tutorial Examples

∟XML::Simple Module - XML Parser and Generator

∟XMLin() and XMLout() Methods

This section describes two key methods in the XML::Simple module, XMLin() and XMLout(), to convert XML text string into a hash structure representing the XML structure and to convert the hash back to a string.

XML::Simple module is an easy API to read and write XML files. It offers two main methods: XMLin() and XMLout().

XMLin(str) - Method to parse the XML input into a hash, and return the reference of the hash. The XML input can be specified in 3 ways:

If the method is called with no parameter, the XML input is in script_name.xml, where script_name is the same name of the calling Perl script file.
If the method is called with a string parameter containing <tag>, the XML input is the string parameter.
If the method is called with a string parameter without any <tag>, the XML input is in the file with the string parameter as file name.

XMLout(ref) - Method to write the hash pointed by the specified reference into an XML string, and return XML string.

If XML::Simple is installed as part of the ActivePerl package. No extra download and installation steps needed.

Here is a simple program to show you how to use XML:Simple:

#- XmlSimpleHello.pl
#- Copyright (c) HerongYang.com. All Rights Reserved.
#
   use XML::Simple;
   my $xs = new XML::Simple();
   my $ref = $xs->XMLin("<p>Hello world!</p>");
   my $xml = $xs->XMLout($ref);
   print $xml;
   exit;

Output:

<opt>Hello world!</opt>

It's interesting to see from the output that the <p> tag has been changed to <opt> during the read and write operations. This is because of the default setting of the option: keeproot. I will explain some of the important options later in this chapter.