Question

I use CSharp, XPath and HTMLAgility Pack. I use XPath strings such as:

"//table[3]/td[1]/span[2]/text() | //table[6]/td[1]/span[2]/text()"
"//table[8]/td[1]/span[2]/text() | //table[10]/td[1]/span[2]/text()"

The difference is only in table numbers. Is it possible to use some other XPath function to replace the XPath or |?

What I actually do: With the first XPath string (where I have table numbers 3 & 6) I extract one value. With the second XPath string (where i have table numbers are 8 & 10) I extract another value.

And additional question about performance – is the XPath string //table[8]/td[1]/span[2]/text() faster than the XPath string with OR //table[8]/td[1]/span[2]/text() | //table[10]/td[1]/span[2]/text()? I ask this because I have many many XPath strings for many many values and if there is a difference which really means I need to try something else. I can’t do the measurement right now that’s why I ask you this question to share your experience.

Answer 1

Firstly, //table[6] looks odd. Are you sure you don’t mean (//table)[6]? (The first selects every table that is the 6th child of its parent; the second selects the sixth table in the document.) I will assume the latter.

In XPath 2.0 you can write

(//table)[position()=(3,6,8,10)]/td[1]/span[2]/text()

In 1.0 that would have to be

(//table)[position()=3 or position()=6 or position()=8 or position()=10]
    /td[1]/span[2]/text()

Or (in either release) you could write

((//table)[3] | (//table)[6] | (//table)[8] | (//table)[10])/td[1]/span[2]/text()

Your question about performance can’t be answered without knowing what XPath implementation you are using.