Re: Is "A != B" equivalent to "not(A = B)"?
> Can someone explain why? It's not very intuitive. The XPath spec has an explicit warning that these are not the same. if A and B are node sets and op is an infix operator A op B is true if _any_ a in A and b in B satisfy a op b so you can say *='x' and it tests if any child has value x, but you can say *!='x' and that is true if any child is not equal to 'x' (which isn't the same as not(*='x-). If A and B are both node sets then A != B is almost always true The only way it can be false is if every member of A has the same string value, and every member of B has the same value. != was a late addition to Xpath, I always thought it was a mistake to add it,almost always you want the not( ... = ...) form. David _____________________________________________________________________ This message has been checked for all known viruses by Star Internet delivered through the MessageLabs Virus Scanning Service. For further information visit http://www.star.net.uk/stats.asp or alternatively call Star Internet for details on the Virus Scanning Service. XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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