XML::Parser SAX in Perl -> the handlers are not getting called

axxo has asked for the wisdom of the Perl Monks concerning the following question:

I am going through a book called XML and Perl. And I am using Windows with Strawberry Perl. I cannot seem to get this thing to work even though I copy pasted it (at first I hand coded everything).

The code is listed below:

use strict; 
use XML::Parser; 

my $parser = XML::Parser->new(Style => 'Stream', 
                              Handlers => {Init  => \&init, 
                                           Start => \&start, 
                                           Char  => \&char, 
                                           End   => \&end, 
                                           Final => \&final}); 

$parser->parsefile(shift);

#################################### 
# These variables keep track       # 
# of each distribution data, and   # 
# are reset at each distribution.  # 
#                                  # 
my $dist_count = 0;                # 
my $dist_cost = 0;                 # 
my $dist_out = 0;                  # 
#################################### 

#################################### 
# These variables keep track       # 
# of the totals which are          # 
# accumulated throughout the     # 
# parsing process                  # 
#                                  # 
my $total_count = 0;               # 
my $total_cost = 0;                # 
my $total_out = 0;                 # 
#################################### 

my $curr_val = "";  ## Retains the text value 
                    ## within the current node 

my @os_avail = ();  ## An array of available 
                    ## operating systems 

sub init { 
  my $e = shift; 

  print "\n***** Software Inventory Report *****\n"; 
  print "-------------------------------------\n\n"; 
}

sub start{ 
  my ($e, $tag, %attr) = @_; 

  if ($tag eq "distribution") { 
    print "*$attr{name} (version $attr{version})*\n"; 
  } 
  elsif ($tag eq "os") { 
    push(@os_avail,$attr{name}); 
  } 
} 

sub char { 
  my ($e, $string) = @_; 
  $curr_val = $string; 
}

sub end { 
  my ($e, $tag) = @_; 

  if ($tag eq "price") { 
    $dist_cost = $curr_val; 
    $total_cost += $curr_val; 
  } 
  elsif ($tag eq "total") { 
    $dist_count += $curr_val; 
    $total_count += $curr_val; 
  } 
  elsif ($tag eq "out") { 
    $dist_out += $curr_val; 
    $total_out += $curr_val; 
  } 
  elsif ($tag eq "distribution") { 
    print "Packages: $dist_count\n"; 
    print "Available: ".($dist_count - $dist_out)."\n"; 
    print "Value ($dist_cost per piece): \$".($dist_count*$dist_cost).
+"\n"; 
    print "-------------------------------------\n\n"; 

    ## Empty the distribution variables 
    $dist_count = 0; 
    $dist_out = 0; 
    @os_avail = (); 
  } 
} 

sub final { 
  my $e = shift; 

  print "Total software packages: $total_count\n"; 
  print "Total software packages available: ".($total_count -$total_ou
+t)."\n"; 
  print "Total cost for $total_count pieces of software: $total_cost\n
+"; 
}
[download]

The following is the input file:

<?xml version="1.0"?> 
<software_inventory> 
   <package name="Dreamweaver" version="4"> 
      <operating_system name="Microsoft Windows"> 
         <licenses_purchased>15</licenses_purchased> 
         <licenses_in_use>8</licenses_in_use> 
      </operating_system> 
      <operating_system name="Apple Mac OS"> 
         <licenses_purchased>10</licenses_purchased> 
         <licenses_in_use>2</licenses_in_use> 
      </operating_system> 
      <price>299.99</price> 
   </package> 
   <package name="Microsoft Visual C++ Enterprise Edition" version="6"
+> 
      <operating_system name="Microsoft Windows"> 
         <licenses_purchased>15</licenses_purchased> 
         <licenses_in_use>8</licenses_in_use> 
      </operating_system> 
      <price>1299.00</price> 
   </package> 
   <package name="XML Spy" version="4.2"> 
      <operating_system name="Microsoft Windows"> 
         <licenses_purchased>15</licenses_purchased> 
         <licenses_in_use>8</licenses_in_use> 
      </operating_system> 
      <price>399.00</price> 
   </package>
   <package name="Borland JBuilder Enterprise" version="6"> 
      <operating_system name="Microsoft Windows"> 
         <licenses_purchased>15</licenses_purchased> 
         <licenses_in_use>8</licenses_in_use> 
      </operating_system> 
      <operating_system name="Apple Mac OS"> 
         <licenses_purchased>10</licenses_purchased> 
         <licenses_in_use>2</licenses_in_use> 
      </operating_system> 
      <operating_system name="Linux"> 
         <licenses_purchased>10</licenses_purchased> 
         <licenses_in_use>2</licenses_in_use> 
      </operating_system> 
      <operating_system name="Solaris Sparc"> 
         <licenses_purchased>10</licenses_purchased> 
         <licenses_in_use>2</licenses_in_use> 
      </operating_system> 
      <price>2999.00</price> 
   </package> 
</software_inventory>
[download]

I am expecting this kind of output (from the book itself):

***** Software Inventory Report ***** 
---------------------------------------------------

*Dreamweaver (version 4)* 
Packages Purchased: 25 
Packages Available: 15 
Cost (299.99 per piece): $7499.75 
----------------------------------------------------

*Microsoft Visual C++ Enterprise Edition (version 6)* 
Packages Purchased: 15 
Packages Available: 7 
Cost (1299.00 per piece): $19485 
----------------------------------------------------

*XML Spy (version 4.2)* 
Packages Purchased: 15 
Packages Available: 7 
Cost (399.00 per piece): $5985 
----------------------------------------------------

*Borland JBuilder Enterprise (version 6)* 
Packages Purchased: 45 
Packages Available: 31 
Cost (2999.00 per piece): $134955 
----------------------------------------------------

Total software packages purchased: 100 
Total software packages available: 60 
Total cost for 100 software packages: 4996.99
[download]

But instead I got this:

***** Software Inventory Report *****
-------------------------------------

Total software packages:
Total software packages available: 0
Total cost for  pieces of software: 4996.99
[download]

Where did it go wrong? How come the output is not the same as expected? Please kindly show me some light ;) Thank you in advance.

Comment on XML::Parser SAX in Perl -> the handlers are not getting called Select or Download Code

Replies are listed 'Best First'.
Re: XML::Parser SAX in Perl -> the handlers are not getting called by toolic (Bishop) on Jan 31, 2011 at 14:52 UTC
use strict and warnings `*** Software Inventory Report *** ------------------------------------- Use of uninitialized value $total_count in concatenation (.) or string + at Total software packages: Use of uninitialized value $total_out in subtraction (-) Use of uninitialized value $total_count in subtraction (-) Total software packages available: 0 Use of uninitialized value $total_count in concatenation (.) or string + at Total cost for pieces of software: 4996.99` [download] Start your debugging by eliminating those warning messages. Better yet... promote your warnings to errors: `use warnings FATAL => 'all';` [download] Update: those warnings occur because you did not initialize those variables before you parse your XML file. Move the `parsefile` line after the variable declarations/initializations.	[reply] [d/l] [select]
Re^2: XML::Parser SAX in Perl -> the handlers are not getting called by axxo (Initiate) on Feb 01, 2011 at 06:26 UTC
Yes I realize it now. Thank you, toolic.	[reply]
Re: XML::Parser SAX in Perl -> the handlers are not getting called by PeterPeiGuo (Hermit) on Jan 31, 2011 at 14:52 UTC
Some tags, for example total and out, they never showed in the XML document. Peter (Guo) Pei	[reply]
Re^2: XML::Parser SAX in Perl -> the handlers are not getting called by axxo (Initiate) on Feb 01, 2011 at 06:26 UTC
Hi Peter Thank you :)	[reply]

Peter (Guo) Pei