use HTML::TokeParser;
use LWP::Simple;

my $content = get('http://www.yoursite.com');

my (@alt, $link);

my $parser = HTML::TokeParser->new(\$content) || die $!;
while (my $token = $parser->get_token) {
    my $type = shift @{$token};
    if ($type eq 'E') {
        my ($tag) = @{$token};
        $link = 0 if $tag eq 'a';
    } elsif ($type eq 'S') {
        my ($tag, $attr, $attrseq, $text) = @{$token};
        $link = 1 if $tag eq 'a';
        next unless $tag eq 'img';
        next unless defined $attr->{'alt'} and length $attr->{'alt'};
        push @alt, { $attr->{'src'} => $attr->{'alt'} } if $link;
    }
}
[download]

use strict;
use HTML::PullParser;

my $p = HTML::PullParser->new(
    file  => shift @ARGV,
    start => 'tagname, @attr'
);

while(my $t = $p->get_token()) {
    my($tagname, %attr) = @$t;
    print "alt text is $attr{alt}", $/
        if exists $attr{alt};
}
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_________
broquaint

use HTML::TreeBuilder;
my $tree = HTML::TreeBuilder->new_from_content($html);

foreach my $img ($tree->look_down('_tag', 'img')) {
    if ($img->attr('alt')) {
        print "Alt tag found: ", $img->attr('alt'), "\n";
    }
}

$tree->delete;
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gav^

#!/usr/bin/perl -w
use strict;
use XML::LibXML;

my $file = $ARGV[0] || die "Usage: $0 [uri|filename]\n";
my $doc = XML::LibXML->new->parse_html_file($file);
print "Alt tags in $file:\n";
foreach my $alt ($doc->findnodes('//img/@alt')) {
  print "Alt tag: ", $alt->nodeValue, "\n";
}
print "Done\n";
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For completeness sake ... this time using HTML::Parser:

use HTML::Parser;

$p = HTML::Parser->new( api_version => 3,
                             start_h => [\&start, "tagname, attr"],
                             end_h => [\&end, "tagname"],
                             marked_sections => 1,
                           );

{
    my $in_link = 0;
    sub start {
        my($tagname, $attr) = @_;
        if ($tagname eq 'a') {
            $in_link = 1;
        } elsif ($in_link and $tagname eq 'img' and exists $attr->{alt
+}) {
            print "IMG: $attr->{src} = $attr->{alt}\n";
        }
    }
    
    sub end {
        $in_link = 0 if ($_[0] eq 'a');
    }
}

$p->parse('sadf dsfg<a href="foo.html"><iMg src="foo.gif" alt="blah"><
+/a>
<img src="bar.gif" alt="nenene"> sdf');

$p->eof();
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