Xpath

[Rajan Thiyagarajan]

<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<CCC/>
<CCC/>
<CCC/>
</AAA>
The following XPath will select all middle BBB elements of the above tree structure.
//BBB[ position() = floor(last() div 2 + 0.5) or position() = ceiling(last() div 2 + 0.5) ]
Can somebody tell me how ?
Thanks
rajan

[Micheal Jacob]

Hi Rajan,
Let see ur xml this way.

 
<AAA> 
<BBB>1</BBB> 
<BBB>2</BBB> 
<BBB>3</BBB> 
<BBB>4</BBB> 
<BBB>5</BBB> 
<BBB>6</BBB> 
<BBB>7</BBB> 
<BBB>8</BBB> 
<CCC>9</CCC> 
<CCC>10</CCC> 
<CCC>11</CCC> 
</AAA> 

so the xpath is //BBB[ position() = floor(last() div 2 + 0.5)]
As it is // it will find all BBB tags.The filter checks whether the element position is matching the other side floor(last() div 2 + 0.5).
from this, last() give you 11,
last() div 2 give you 5.5
last() div 2 + 0.5 give you 6
so it will find the 6 BBB element.
Thats how it arrives at middle element.
Hope this helps you.
Micheal

[Micheal Jacob]

Hi Rajan,
Please ignore the above mail,
Use same xml but the answer will be 4 th BBB tag.
Because inside // the context is changed
so last() gives you 8
last() div 2 gives you 4
last() div 2 + 0.5 gives you 4.5
floor(last()...) gives you 4
so it selects the BBB tag whose position is 4.
Micheal

[Rajan Thiyagarajan]

Thanks Michael.