Re: [xsl] The operator '!=' returns false when one operand doesn't exist

["Vasu Chakkera" <vasucv@xxxxxxxxxxx>]

The spec says so.. :)
This is the very reason why it is best advised not to use '!=' unless u are 
100% sure what you want to do.You should instead use *not* ..
as in **not($x = 'text')**as opposed to **$x != 'text'**
the former is most likely to mean the intended meaning.
Vasu


> From: Jerome Louvel <jerome_louvel@xxxxxxxx>
> Reply-To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> To: XSL-List@xxxxxxxxxxxxxxxxxxxxxx
> Subject: [xsl] The operator '!=' returns false when one operand doesn't 
> exist
> Date: Wed, 7 Aug 2002 08:32:17 -0700 (PDT)
>
> Hi All,
>
> We have an issue with the XPath '!=' operator that has
> a strange behavior when one of its operand doesn't
> exist in the instance document. It returns 'false"
> when you would expect "true" or some kind of exception
> to be raised.
>
> Sample stylesheet:
> ------------------
> <?xml version="1.0" encoding="UTF-8"?>
> <xsl:transform version="1.0"
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
> 	<xsl:template match="/">
> 		<data>
> 			<xsl:value-of select="/data/a != /data/b"/>
> 		</data>
> 	</xsl:template>
> </xsl:transform>
>
> Instance:
> ---------
> <?xml version="1.0"?>
> <data>
> 	<a>10</a>
> </data>
>
> This transformation will return 'false'.
> If you add <b>11</b> under element a, or even an empty
> <b/>, the result is becoming 'true'.
>
> Could somebody explain me why we get such a result
> (with MSXML 4.0 as well as Xalan)?
> Is there a simple way, extension function or XPath
> expression to would make this work as "expected" (true
> is one of this operand doesn't exist)?
>
> Thanks for your help!
> Jerome.
>
>
>
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