Hello Monks, I am new to programming in general and perl in particular, and I am afraid I am attempting to walk before I can crawl with a little code project.

I am using XML:Simple to parse search results, and hopefully in the future, correct for duplicate entries, return a tally of results, and return certain other data as well.

I am hoping one of you will kindly tell me where I am going wrong with my code to access a reference ID in the sample XML file below. When I run my routine on a sample file with two identical records, it works, returning two identical reference paths from the XML results. But when I run it on an XML file with only one result the program gives me a "not an array reference" error, and when I run it on a search with 100 plus results, I get an "not a hash reference" error.

Here is the code: 
 #!/usr/bin/perl

# turn on perl safety features
    use strict;
    use warnings;

# work out the name of the argument we're looking for

my $file_in = $ARGV[0] or die "Must specify file on command line";

#Use module
use XML::Simple;
use Data::Dumper;

# create object
my $xml = new XML::Simple (KeyAttr=>[]);

# read XML file
my $data = $xml->XMLin($file_in);

#declare array node variable
my ($e);

# dereference hash ref
# access reference array
foreach $e (@{$data->{ppsarticleresponse}->{ppsarticleresultset}->{pps
+article}->{article}})
{
        print $e->{reference}, "\n";
}

exit(0);

[download]
And here is a sample of the XML that XML:Simple is parsing for me: 
 <?xml version="1.0" encoding="utf-8"?>
<ppsresponse>
  <ppsarticleresponse xmlns="http://global.factiva.com.ezproxy.insead.
+edu/pps/2.0">
    <ppsarticleresultset count="133">
      <ppsarticle>
        <article>
          <accessionno>MTPW000020090731e57v004mr</accessionno>
          <reference>distdoc:archive/ArchiveDoc::Article/MTPW000020090
+731e57v004mr</reference>
          <baselanguage>EN</baselanguage>
          <copyright>(c) 2009 M2 Communications, Ltd. All Rights Reser
+ved.   </copyright>
          <headline>
            <paragraph display="Proportional" truncation="None" lang="
+EN">Anadys Pharmaceuticals, Inc (NASDAQ:ANDS) is the Highest Percenta
+ge Gainers Among NASDAQ Stocks During Morning Trading Hours; Microsof
+t Corporation (NASDAQ:<hlt>MSFT</hlt>) And Orthofix International NV 
+(NASDAQ:OFIX) Round Out Top Three Percentage Gainers During Morning T
+rading Hours</paragraph>
          </headline>
          <leadparagraph>
            <paragraph display="Proportional" truncation="None">Dallas
+, TX - LiquidTycoon.com is pleased to alert investors of stocks on th
+e move.</paragraph>
            <paragraph display="Proportional" truncation="None">Anadys
+ Pharmaceuticals, Inc (NASDAQ:ANDS) is among the gainers on NASDAQ in
+ the early trade hours. The stock is up 60.0% to $2.88 with over 1.63
+ million shares being traded within few minutes of trade. On July 30,
+ 2009, Anadys Pharmaceuticals, Inc announced the finalization of the 
+protocol for the Company's Phase II trial of ANA598 in combination wi
+th pegylated interferon-alpha and ribavirin in hepatitis C patients. 
+Anadys Pharmaceuticals, Inc is a biopharmaceutical company focused to
+ develop medicines in the areas of hepatitis C and oncology. The Comp
+any is developing ANA598, a small-molecule, non-nucleoside inhibitor 
+of the NS5B polymerase for the treatment of hepatitis C and ANA773, a
+n oral Toll-like receptor 7 (TLR7) agonist prodrug for the treatment 
+of hepatitis C and cancer.</paragraph>
          </leadparagraph>
          <publicationdate>
            <date>2009-07-31</date>
          </publicationdate>
          <sourcename>M2 Presswire</sourcename>
          <company code="oficks">
            <name>Orthofix International N.V.</name>
            <newsmentions>0</newsmentions>
            <newshits>0</newshits>
          </company>
          <company code="scrptg">
            <name>Anadys Pharmaceuticals Inc</name>
            <newsmentions>0</newsmentions>
            <newshits>0</newshits>
          </company>
          <company code="mcrost">
            <name>Microsoft Corporation</name>
            <newsmentions>0</newsmentions>
            <newshits>0</newshits>
          </company>
          <industry code="i3302">
            <name>Computers/Electronics</name>
          </industry>
          <industry code="i3302021">
            <name>Applications Software</name>
          </industry>
          <industry code="i257">
            <name>Pharmaceuticals</name>
          </industry>
          <industry code="i330202">
            <name>Software</name>
          </industry>
          <industry code="icomp">
            <name>Computing</name>
          </industry>
          <industry code="i3302020">
            <name>Systems Software</name>
          </industry>
          <industry code="i372">
            <name>Medical Equipment/Supplies</name>
          </industry>
          <industry code="i951">
            <name>Health Care</name>
          </industry>
          <industry code="iphmed">
            <name>Medical/Surgical Instruments/Apparatus/Devices</name
+>
          </industry>
          <region code="usa">
            <name>United States</name>
          </region>
          <region code="namz">
            <name>North American Countries/Regions</name>
          </region>
          <newssubject code="c42" position="0">
            <name>Labor/Personnel Issues</name>
          </newssubject>
          <newssubject code="ghepat" position="0">
            <name>Hepatitis</name>
          </newssubject>
          <newssubject code="mstock" position="0">
            <name>Stock Exchanges</name>
          </newssubject>
          <newssubject code="npress" position="0">
            <name>Press Release</name>
          </newssubject>
          <newssubject code="ccat" position="0">
            <name>Corporate/Industrial News</name>
          </newssubject>
          <newssubject code="gcat" position="0">
            <name>Political/General News</name>
          </newssubject>
          <newssubject code="ghea" position="0">
            <name>Health</name>
          </newssubject>
          <newssubject code="gmed" position="0">
            <name>Medical Conditions</name>
          </newssubject>
          <newssubject code="m11" position="0">
            <name>Equity Markets</name>
          </newssubject>
          <newssubject code="mcat" position="0">
            <name>Commodity/Financial Market News</name>
          </newssubject>
          <newssubject code="ncat" position="0">
            <name>Content Types</name>
          </newssubject>
          <newssubject code="nfact" position="0">
            <name>Factiva Filters</name>
          </newssubject>
          <newssubject code="nfce" position="0">
            <name>FC&amp;E Exclusion Filter</name>
          </newssubject>
          <newssubject code="nfcpin" position="0">
            <name>FC&amp;E Industry News Filter</name>
          </newssubject>
          <sourcecode>MTPW</sourcecode>
          <tailparagraphs>
            <paragraph display="Proportional" truncation="None">Micros
+oft Corporation (NASDAQ:<hlt>MSFT</hlt>) is gaining momentum in the e
+arly morning trading hours. The stock moved up 0.67% to $23.98 on a t
+hinly traded volume of 94k shares within few minutes of trade. On Jul
+y 30, 2009, Microsoft Corp announced that it is collaborating with co
+mScore Inc to develop a digital media planning solution, named the Re
+ach and Frequency Planner (RF Planner), which will allow brand advert
+isers to predict reach, frequency and audience composition at the ad 
+placement level. Microsoft Corporation develops, manufactures, licens
+es and supports a range of software products for computing devices. T
+he Company's software products include operating systems for servers,
+ personal computers and intelligent devices, server applications for 
+distributed computing environments, information worker productivity a
+pplications, business solution applications, high-performance computi
+ng applications and software development tools and video games.</para
+graph>
            <paragraph display="Proportional" truncation="None">Orthof
+ix International NV (NASDAQ:OFIX) climbed over 20.0% to $28.85 on a l
+ow traded volume of 94k shares. The 52 week range for the stock is $3
+0.47 and $8.65. On July 30, 2009, Orthofix International N.V. announc
+ed that based on its results for the first half of 2009, the Company 
+reaffirmed its fiscal 2009 guidance. Orthofix International N.V. is m
+edical device company offering a line of surgical and non-surgical pr
+oducts for the spine, orthopedics, sports medicine and vascular marke
+t sectors. Its products are designed to address the lifelong bone-and
+-joint health needs of patients of all ages, and to help them achieve
+ a more active and mobile lifestyle.</paragraph>
            <paragraph display="Proportional" truncation="None">Liquid
+ Tycoon alerts its members on stocks that could generate higher than 
+average returns. These include stocks with huge volume, penny stocks 
+that are moving to the upside quickly, penny stocks with buy signals 
+and companies with news. Our alerts are well known for producing incr
+edible results in a short amount of time and our members have made ou
+tstanding profits of over 100%.</paragraph>
            <paragraph display="Proportional" truncation="None">ABOUT 
+Liquid Tycoon</paragraph>
            <paragraph display="Proportional" truncation="None">Liquid
+Tycoon.com is a leading stock web site that provides free alerts on s
+tocks that are poised to make big gains. LiquidTycoon.com also tracks
+ small cap penny stocks that could be on the brink of a massive break
+out. To feature a company on our web site please contact us at info@ 
+LiquidTycoon.com</paragraph>
            <paragraph display="Proportional" truncation="None">Liquid
+ Tycoon is an independent electronic publication that provides inform
+ation on selected publicly traded companies. Liquid Tycoon is not a r
+egistered investment advisor or broker-dealer. Liquid Tycoon affiliat
+es, officers, directors and employees may buy and sell additional sha
+res in any company mentioned herein and may profit in the event those
+ shares rise in value. Please do your own Due Diligence before invest
+ing in any of the stocks mentioned above.</paragraph>
            <paragraph display="Proportional" truncation="None">M2 Com
+munications disclaims all liability for information provided within M
+2 PressWIRE. Data prepared by named party/parties. Further informatio
+n on M2 PressWIRE can be obtained at <elink type="webpage" reference=
+"http://www.presswire.net">http://www.presswire.net</elink> on the wo
+rld wide web. Inquiries to info@m2.com.</paragraph>
          </tailparagraphs>
          <contact>Liquid Tycoon
 | e-mail: info@LiquidTycoon.com
 | Tel: +1 214 556 6798   </contact>
          <logo source="http://logos.factiva.com.ezproxy.insead.edu" i
+mage="mtpwLogo.gif"></logo>
          <wordcount>679</wordcount>
        </article>
        
        <article>
          <accessionno>MTPW000020090731e57v004mr</accessionno>
          <reference>distdoc:archive/ArchiveDoc::Article/MTPW000020090
+731e57v004mr</reference>
          <baselanguage>EN</baselanguage>
          <copyright>(c) 2009 M2 Communications, Ltd. All Rights Reser
+ved.   </copyright>
          <headline>
            <paragraph display="Proportional" truncation="None" lang="
+EN">Anadys Pharmaceuticals, Inc (NASDAQ:ANDS) is the Highest Percenta
+ge Gainers Among NASDAQ Stocks During Morning Trading Hours; Microsof
+t Corporation (NASDAQ:<hlt>MSFT</hlt>) And Orthofix International NV 
+(NASDAQ:OFIX) Round Out Top Three Percentage Gainers During Morning T
+rading Hours</paragraph>
          </headline>
          <leadparagraph>
            <paragraph display="Proportional" truncation="None">Dallas
+, TX - LiquidTycoon.com is pleased to alert investors of stocks on th
+e move.</paragraph>
            <paragraph display="Proportional" truncation="None">Anadys
+ Pharmaceuticals, Inc (NASDAQ:ANDS) is among the gainers on NASDAQ in
+ the early trade hours. The stock is up 60.0% to $2.88 with over 1.63
+ million shares being traded within few minutes of trade. On July 30,
+ 2009, Anadys Pharmaceuticals, Inc announced the finalization of the 
+protocol for the Company's Phase II trial of ANA598 in combination wi
+th pegylated interferon-alpha and ribavirin in hepatitis C patients. 
+Anadys Pharmaceuticals, Inc is a biopharmaceutical company focused to
+ develop medicines in the areas of hepatitis C and oncology. The Comp
+any is developing ANA598, a small-molecule, non-nucleoside inhibitor 
+of the NS5B polymerase for the treatment of hepatitis C and ANA773, a
+n oral Toll-like receptor 7 (TLR7) agonist prodrug for the treatment 
+of hepatitis C and cancer.</paragraph>
          </leadparagraph>
          <publicationdate>
            <date>2009-07-31</date>
          </publicationdate>
          <sourcename>M2 Presswire</sourcename>
          <company code="oficks">
            <name>Orthofix International N.V.</name>
            <newsmentions>0</newsmentions>
            <newshits>0</newshits>
          </company>
          <company code="scrptg">
            <name>Anadys Pharmaceuticals Inc</name>
            <newsmentions>0</newsmentions>
            <newshits>0</newshits>
          </company>
          <company code="mcrost">
            <name>Microsoft Corporation</name>
            <newsmentions>0</newsmentions>
            <newshits>0</newshits>
          </company>
          <industry code="i3302">
            <name>Computers/Electronics</name>
          </industry>
          <industry code="i3302021">
            <name>Applications Software</name>
          </industry>
          <industry code="i257">
            <name>Pharmaceuticals</name>
          </industry>
          <industry code="i330202">
            <name>Software</name>
          </industry>
          <industry code="icomp">
            <name>Computing</name>
          </industry>
          <industry code="i3302020">
            <name>Systems Software</name>
          </industry>
          <industry code="i372">
            <name>Medical Equipment/Supplies</name>
          </industry>
          <industry code="i951">
            <name>Health Care</name>
          </industry>
          <industry code="iphmed">
            <name>Medical/Surgical Instruments/Apparatus/Devices</name
+>
          </industry>
          <region code="usa">
            <name>United States</name>
          </region>
          <region code="namz">
            <name>North American Countries/Regions</name>
          </region>
          <newssubject code="c42" position="0">
            <name>Labor/Personnel Issues</name>
          </newssubject>
          <newssubject code="ghepat" position="0">
            <name>Hepatitis</name>
          </newssubject>
          <newssubject code="mstock" position="0">
            <name>Stock Exchanges</name>
          </newssubject>
          <newssubject code="npress" position="0">
            <name>Press Release</name>
          </newssubject>
          <newssubject code="ccat" position="0">
            <name>Corporate/Industrial News</name>
          </newssubject>
          <newssubject code="gcat" position="0">
            <name>Political/General News</name>
          </newssubject>
          <newssubject code="ghea" position="0">
            <name>Health</name>
          </newssubject>
          <newssubject code="gmed" position="0">
            <name>Medical Conditions</name>
          </newssubject>
          <newssubject code="m11" position="0">
            <name>Equity Markets</name>
          </newssubject>
          <newssubject code="mcat" position="0">
            <name>Commodity/Financial Market News</name>
          </newssubject>
          <newssubject code="ncat" position="0">
            <name>Content Types</name>
          </newssubject>
          <newssubject code="nfact" position="0">
            <name>Factiva Filters</name>
          </newssubject>
          <newssubject code="nfce" position="0">
            <name>FC&amp;E Exclusion Filter</name>
          </newssubject>
          <newssubject code="nfcpin" position="0">
            <name>FC&amp;E Industry News Filter</name>
          </newssubject>
          <sourcecode>MTPW</sourcecode>
          <tailparagraphs>
            <paragraph display="Proportional" truncation="None">Micros
+oft Corporation (NASDAQ:<hlt>MSFT</hlt>) is gaining momentum in the e
+arly morning trading hours. The stock moved up 0.67% to $23.98 on a t
+hinly traded volume of 94k shares within few minutes of trade. On Jul
+y 30, 2009, Microsoft Corp announced that it is collaborating with co
+mScore Inc to develop a digital media planning solution, named the Re
+ach and Frequency Planner (RF Planner), which will allow brand advert
+isers to predict reach, frequency and audience composition at the ad 
+placement level. Microsoft Corporation develops, manufactures, licens
+es and supports a range of software products for computing devices. T
+he Company's software products include operating systems for servers,
+ personal computers and intelligent devices, server applications for 
+distributed computing environments, information worker productivity a
+pplications, business solution applications, high-performance computi
+ng applications and software development tools and video games.</para
+graph>
            <paragraph display="Proportional" truncation="None">Orthof
+ix International NV (NASDAQ:OFIX) climbed over 20.0% to $28.85 on a l
+ow traded volume of 94k shares. The 52 week range for the stock is $3
+0.47 and $8.65. On July 30, 2009, Orthofix International N.V. announc
+ed that based on its results for the first half of 2009, the Company 
+reaffirmed its fiscal 2009 guidance. Orthofix International N.V. is m
+edical device company offering a line of surgical and non-surgical pr
+oducts for the spine, orthopedics, sports medicine and vascular marke
+t sectors. Its products are designed to address the lifelong bone-and
+-joint health needs of patients of all ages, and to help them achieve
+ a more active and mobile lifestyle.</paragraph>
            <paragraph display="Proportional" truncation="None">Liquid
+ Tycoon alerts its members on stocks that could generate higher than 
+average returns. These include stocks with huge volume, penny stocks 
+that are moving to the upside quickly, penny stocks with buy signals 
+and companies with news. Our alerts are well known for producing incr
+edible results in a short amount of time and our members have made ou
+tstanding profits of over 100%.</paragraph>
            <paragraph display="Proportional" truncation="None">ABOUT 
+Liquid Tycoon</paragraph>
            <paragraph display="Proportional" truncation="None">Liquid
+Tycoon.com is a leading stock web site that provides free alerts on s
+tocks that are poised to make big gains. LiquidTycoon.com also tracks
+ small cap penny stocks that could be on the brink of a massive break
+out. To feature a company on our web site please contact us at info@ 
+LiquidTycoon.com</paragraph>
            <paragraph display="Proportional" truncation="None">Liquid
+ Tycoon is an independent electronic publication that provides inform
+ation on selected publicly traded companies. Liquid Tycoon is not a r
+egistered investment advisor or broker-dealer. Liquid Tycoon affiliat
+es, officers, directors and employees may buy and sell additional sha
+res in any company mentioned herein and may profit in the event those
+ shares rise in value. Please do your own Due Diligence before invest
+ing in any of the stocks mentioned above.</paragraph>
            <paragraph display="Proportional" truncation="None">M2 Com
+munications disclaims all liability for information provided within M
+2 PressWIRE. Data prepared by named party/parties. Further informatio
+n on M2 PressWIRE can be obtained at <elink type="webpage" reference=
+"http://www.presswire.net">http://www.presswire.net</elink> on the wo
+rld wide web. Inquiries to info@m2.com.</paragraph>
          </tailparagraphs>
          <contact>Liquid Tycoon
 | e-mail: info@LiquidTycoon.com
 | Tel: +1 214 556 6798   </contact>
          <logo source="http://logos.factiva.com.ezproxy.insead.edu" i
+mage="mtpwLogo.gif"></logo>
          <wordcount>679</wordcount>
        </article>

    </ppsarticle>
    </ppsarticleresultset>
    </ppsarticleresponse>
    </ppsresponse>

[download]

In reply to Parsing XML: Not an Array/Hash Reference Error by leighgable

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