Using XPath count() with contains()

Question

I am working with the following (suboptimal) XML:

<a>
  <b>
    <c>X:1 Y:0</c>
    <c>X:1 Y:0</c>
    <c>X:2 Y:0</c>
  </b>
  <b>
    <c>X:1 Y:0</c>
    <c>X:2 Y:0</c>
  </b>
</a>

I am trying to use XPath to count the number of <c> nodes whose contents contain X:1:

count(contains(/a/b/c, 'X:1'))

However, this returns an error rather than returning the expected count of 3.

What am I doing wrong?

Answer 1

That isn't how you use contains(). Try

count(/a/b/c[contains(., 'X:1')])

Answer 2

Probably a little bit more efficient (if the property exhibited in the provided XML document isn't accidental):

count(/a/b/c[starts-with(., 'X:1')])