"I want to parse xml from pubmed."
This is not the right idea.

Pubmed provides a huge amount of software to access their site in C, C++ and Perl.

toolkits:
http://www.ncbi.nlm.nih.gov/guide/howto/dwn-software/ Bio-Perl Toolkit:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC187536/

There is a whole bunch of this stuff available for
Perl and C. There is so much stuff available that it
might take a few days to discover and understand the
options.

I recommend that you look at the free-ware that is
available and see what you can do with it.

I just gave a few links to get started.
There are many more.