I'm not sure I understand - it looks like you want to have the "ch(^>*)" in @tags treated as a regex, but you're not actually doing that. Since you can't use a regex as a hash key to do what you want, you might consider using an array of regexes. Also, when matching the tag, you probably want to match up to the first space or >: 
my @tag_regexes = ( qr/^kt$/,
                    qr/^bold$/,
                    qr/^ital$/,
                    qr/^ch\d$/,
                  );

while (defined (my $line = <DATA>)) {
    $line =~ /<([^ >]+)/;
    my $tag = $1;
    die "Invalid element $tag in $.. Cannot proceed due to the above e
+rror\n"
        unless grep { $tag =~ $_ } @tag_regexes;
    print "tag: $tag\n";
}


__DATA__
<kt>
<bold>
<ital>
<ch1>
<kt someattribute="somevalue">
<bold someattribute="somevalue">
<ital someattribute="somevalue">
<ch1 someattribute="somevalue">

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In reply to Re: Matching elements in a array by duckyd
in thread Matching elements in a array by rsriram

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