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XPath function

concat()

Joins two or more strings. There is no + for strings in XPath.

concat() takes two or more arguments and returns them joined. It is the only string join in XPath 1.0 — the + operator is arithmetic and will try to convert its operands to numbers.

Node-set arguments are converted to their string-value first, which means only the first node of each is used.

Syntax
concat(string, string, string*) → string
Returns
string
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.

  • concat('WIDGET', '-', '1')on order.xmlRun
    WIDGET-1
  • concat(//customer/@country, ':', //order/@tier)on order.xmlRun
    NO:gold

Run your own expression

What catches people out

  • concat() requires at least two arguments.
  • 'a' + 'b' is not string concatenation. It is arithmetic, and produces NaN.
  • A node-set argument contributes only its first node's string-value.

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.

order.xml
<?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

All 34 XPath entries

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