use XML::Checker::Parser;

 my %expat_options = (KeepCDATA => 1, 
                      Handlers => [ Unparsed => \&my_Unparsed_handler ]);
 my $parser = new XML::Checker::Parser (%expat_options);

 eval {
     local $XML::Checker::FAIL = \&my_fail;
     $parser->parsefile ("fail.xml");
 };
 if ($@) {
     print $@;
 }
 else{
 print "xml has been validated";
 }
sub my_fail {
     my $code = shift;
     die XML::Checker::error_string ($code, @_) if $code < 200;
     XML::Checker::print_error ($code, @_);
 }

##</code><code>##

<!DOCTYPE a [
    <!ELEMENT a (b,c!)>
    <!ELEMENT b (#PCDATA)>
    <!ELEMENT c (#PCDATA)>
]>
<a>
"something should not be here"
<b></b>
<c></c>
</a>