Yes, it is possible, see Re: Need to write a regular expression in perl for the below xml code.

But, since this is FAQ, it doesn't bode well you weren't able to find it on your own

It's easy enough to read it in. This will slurp it in as a big string:

my $xml_text = do { local(@ARGV, $/) = 'myfile.xml'; <> };
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But actually using the content is a different matter. XML is pretty complex to parse, which is why people generally use a pre-written XML module. Parsing a limited subset of XML is generally doable using regular expressions, but I'd still consider this a last resort.

Any particular reason why you're not using modules? See Top Seven (Bad) Reasons Not To Use Modules.

hey thanks, I have tried the way you provided to read the .xml file. When I print out the "$xml_text" it seems it is only part of the xml file

Before I post a question here. I have tried use a while loop

 while(<STDIN>){
    print $_;
}
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which produce the same output with your method. If I put the xml file to a .txt file. It reads in just fine. the reason I cannot use module is because it is an home work requirement

See Basic debugging checklist, Data::Dump, perlintro