Example: extracting information from an XML document

Printing the price of wines with a rating of 9.

pyx wine.xml | perl ex1.pl

if( /^\(rating/) { $in_rating= 1; }      # entering the rating element
elsif( $in_rating && (/^-(\d+)/))        # the value in the rating element
  { $rating= $1; }                       #   grab it!
elsif( /^\)rating/) { $in_rating= 0; }   # leaving the rating element

elsif( /^\(price/)  { $in_price= 1; }    # entering the price element
elsif( $in_price && (/^-(\d+)/))         # the value ine the price element
  { $price= $1;                          #   grab it
    print "$price\n" if( $rating >= 9);  # are we interested?
  } 
elsif( /^\)price/) { $in_price= 0; }     # leaving the price element

Example: word count

XML::Parser