Why $stock_url->as_HTML report can't call method as

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

The perl report "Can't call method "as_HTML" on an undefined value at m.pl line 27. ", The $stock_url are a HTML::ELEMENTS type same as the line 25, why report error ?

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#!/usr/bin/perl

use HTML::Tree;
use HTML::Element;

$url="http://biz.yahoo.com/research/earncal/today.html";
$file="/tmp/today.html";
$arg_2="-O$file";
system ( "wget", $url, $arg_2) ;

print "Content-type: text/html \n\n";

$tree = HTML::TreeBuilder->new();
$tree->parse_file( $file );

@tables = $tree->find('table');

@stocks = @tables[5]->find('tr');

print "<b>Totally found ".scalar(@stocks)." Stocks.</b>";
print "<br><b>Fetching ...</b><br>";

for( $i = 3; $i < scalar(@stocks); $i++){

print @stocks[$i]->as_HTML; # line 25
$stock_url = @stocks[$i]->find('a');
print $stock_url->as_HTML; # line 27

}
[download]

Comment on Why $stock_url->as_HTML report can't call method as_HTML ? Download Code

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Re: Why $stock_url->as_HTML report can't call method as_HTML ? by Corion (Patriarch) on May 12, 2010 at 18:01 UTC
To quote the HTML::Element documentation: In list context, returns a list of elements at or under $h that have any of the specified tag names. In scalar context, returns the first (in pre-order traversal of the tree) such element found, or undef if none. So, likely, the following code finds no element: `@stocks[$i]->find('a');` [download] Maybe you want the following code? `my $stock_url = @stocks[$i]->find('a') or die "Couldn't find a link in " . @stocks[$i]->as_HTML;` [download] As an aside, you better write it as `$stocks[$i]->find('a');` [download] which Perl would also recommend, if you were running with warnings enabled.	[reply] [d/l] [select]
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