XPath function
number()
Converts to a number, producing NaN rather than an error when it cannot — which is how bad data passes silently.
number() converts its argument to a number. A string that is not a valid number becomes NaN, and NaN compares false against everything, including itself.
That makes NaN hard to detect. The idiom is `number(x) != number(x)`, which is only true for NaN.
- Syntax
number(object?) → number- Returns
- number
- Kind
- Function
- Version
- XPath 1.0 (libxml2)
Worked examples
Each result below is what the evaluator returned, asserted on every test run. An empty result means an empty node-set — which is an answer, not an error.
The sample documents
Every example on this page runs against this document. The sitemap one is namespaced on purpose — almost every real XML document is, and that changes which expressions match.
<?xml version="1.0" encoding="UTF-8"?>
<order id="A-1001" tier="gold">
<customer country="NO">Ada Lovelace</customer>
<lines>
<line sku="WIDGET-1" qty="2"><price>14.50</price></line>
<line sku="WIDGET-2" qty="1"><price>39.00</price></line>
<line sku="GIFT-WRAP" qty="1"><price>0.00</price></line>
</lines>
<note> Deliver after 09:00 </note>
</order>Related
- sum()Adds the numeric values of every node in a set. One non-numeric node makes the whole result NaN.
- round(), floor() and ceiling()The three rounding functions. round() goes to the nearest integer, breaking ties upward — including for negatives.
- string()Converts anything to a string — and for a node-set, takes only the first node in document order.
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