Store XML attributes into an array

Hi, me again with this question:

I have an XML file and want to store certain attributes into an array.

The XML file looks like this:

    ?xml version="1.0" encoding="utf-8"?>
    <root>
       <cell id="" type="">
          <tree id="" type="">
             <vertice end="" id="" length="5.4915" start="" type="">
                <vertice end="" id="" length="6.3272" start="" type="">
                    .....

so nothing special and the only attribute with a value is "length". This lengths I want to store in an arrary/row vector. I tried the xmlread and xml2struct commands, but from there on did not know how to continue..any advice is welcome, thanks!