[xml] How to select a node based on attribute values?

[Yan Seiner <yan seiner com>]

Fist off, I'm a total newbie when it comes to libxml.  I've been able to 
work my way through some examples, and produce working code, but I'm not 
entirely happy with the result, and I would like some advice.

I have an XML tree that looks like this:

<root>
   <plc id="1">
      <some stuff/>
   </plc>
   <plc id="2">
      <some other stuff/>
   </plc>
</root>

I have a relatively small number (< 50) of the plc nodes, but the whole 
tree is pretty big.

What is the best (or simplest way) to retrieve the information for plc 2?

Should I pull all of the plc elements using xmlXPathEvalExpression, and 
then iterate over them with xmlGetProp looking for an id attribute with 
a value of "2"?

Or is there some other way to directly specify, I want this element with 
these attributes?

Thanks for any guidance....  The docs are really thorough, but libxml is 
so rich that the learning curve is a killer.....

--Yan