How to find the max attribute from an XML document using Xpath 1.0

Question

Is there a way to query an XML document to return the maximum of a given attribute using Xpath 1.0 ?

For example is there a way to get the max id ?

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Answer 1

I've found that answers like the lwburk's or timbooo's work fine for attributes representing numbers having just one digit. However, if the attribute is a number having more than one digit, extrange things seem to happen when comparing between attributes' values. For example, try changing the original XML data with something like this:

Running the suggested snippets won't work. I got a solution using the casting operator xs:int() applied on id attribute, like in:

/library/book[not(xs:int(@id) <= preceding-sibling::book/@id) and not(xs:int(@id) <=following-sibling::book/@id)]

That will give the correct answer!