want to refer to some cousin child value in xml path

Question

this is the XML doc

 <CT>
  <CHILD 1>  10   </CHILD 1>
  <CHILD 2>   20    </CHILD 2>
 </CT>

  <TH>
    <CHILD 3> 100   </CHILD 3>
    <CHILD 4> 200   </CHILD 4>
 </TH>

  <CT>
  <CHILD 1>  30  </CHILD 1>
  <CHILD 6>  40  </CHILD 6>
 </CT>

  <TH>
    <CHILD 7>  300  </CHILD 7>
    <CHILD 8>  400  </CHILD 8>
 </TH>

I want to fetch the value 30 for which I have used the following xpath root/parent/th../ct/child1

I cannot change root/parent/th which is fixed according to my requirements but I can change the rest of the xpath starting from ../ct/child1

Answer 1

You have error in your xpath expression: not /th../ but /th/../

Also, /root/parent/th selects two th elements and it's not clear which one should be used because both of them have preceding ct with child1 child.

Straightforward answer is

/root/parent/TH[last()]/preceding-sibling::CT[1]/CHILD1

I.e. first preceding sibling element CT of last TH.

But for more useful answer we need more info.