Example: extracting information from an XML document

#!/bin/perl -w
use strict;
use XML::Parser;
my( $class, $cheap_winery, $winery, $cheap_price, $price, $in_winery, $in_price);
my $parser= new XML::Parser( 
    Handlers => { Start => \&start,
                  End   => \&end,
                  Char  => \&char
                });
$parser->parsefile( "wine.xml");
sub start
  { my( $expat, $element, %att)= @_;
    if(    $element eq "class")
      { $class= $att{name}; }
    elsif( $element eq "winery")
      { $in_winery= 1; $winery= ""}
    elsif( $element eq "price")
      { $in_price= 1; $price= ""}
  }
sub char
  { my( $expat, $string)= @_;
    if(    $in_winery) { $winery .= $string; }
    elsif( $in_price) { $price .= $string; }
  }
sub end
  { my( $expat, $element)= @_;
    if(    $element eq "winery")
      { $in_winery= 0; }
    elsif( $element eq "price")
      { if( !$cheap_price || ($price < $cheap_price) )
          { $cheap_winery= $winery;
            $cheap_price= $price;
          }
        $in_price= 0;
      }
    elsif( $element eq "class")
      { print "$class: $cheap_winery (\$$cheap_price)\n";
        $cheap_price=0;
      }
  }