Question

I have a following XML.

<root>
    <a>
    </a>
    <a b="ar34" >
    </a>
    <a c="utr45">
    </a>
</root>

I want to do the count where attribute “b” is not present.
I am using the following but not getting the count

count(//*[string-length(a/@b) = 0]

How I can do this? Thanks

Answer 1

count( //a[not(@b)] )

Here’s a verbose explanation:

1. What do you want to count? <a> tags. So you start with count( a )
2. Where are these <a> tags? Everywhere in the document. So count( //a ) it is then.
3. But you want to filter out some <a> tags, so you have to use a predicate (the bit in the square brackets): count( //a[ ... ] )
4. You want to only count those tags that have no @b attribute, so you put not(@b) in the predicate. (You can do this because an attribute interpreted as a boolean is true if the attribute is present and false if it isn’t.)