.. _not:

===
not
=== 

Negates a boolean value

Description
~~~~~~~~~~~
The fn:not function accepts a sequence of items, from which it calculates the 
effective boolean value of the sequence as a whole before negating it. This 
means that when $arg is either a single boolean value false, a zero-length 
string, the number 0 or NaN, or the empty sequence, it returns true. Otherwise, 
it returns false.

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   :widths: 40 60
   :header-rows: 1

   * - **Parameters**
     - **Description**
   * - arg:boolean()
     - 

Examples
~~~~~~~~
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   :widths: 25 25 50
   :header-rows: 1

   * - **XPath**
     - **Results**
     - **Explanation**
   * - not(32 > 20)
     - false
     - 
   * - not(doc('http://www.functx.com/input/catalog.xml')//product)
     - false
     - there is at least one product element in catalog.xml
   * - not(true())
     - false
     - 
   * - not(())
     - true
     - 
   * - not('')
     - true
     - 
   * - not(0)
     - true
     - 
   * - not(<e>false</e>)
     - false
     - 

See Also
~~~~~~~~

.. toctree::
   :titlesonly:
   :glob:

* :ref:`boolean`.
* :ref:`true`.
* :ref:`false`.