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At 10:38 AM 1/19/2003 -0800, Joe English wrote: >W. E. Perry wrote: > > > > I'm sorry, Jonathan, I don't understand. What is > > > > return $stock/price / ($stock/revenues - $stock/expenses) > > > > except the execution of subtraction and division arithmetic > > operations agains t the 'values' of $stock/price, > > $stock/revenues, and $stock/expenses? And if your query > > is against XML, then the values of those i tems are > > runs of Unicode text, and your arithmetic operations > > are effectively meaningless. > >Not necessarily: the infix operator "-" can easily be >defined as an operation on strings. Parse the left and >right operands as numbers (raising an error if they're not >syntactically valid), subtract one from the other, then >format the result as a string. If an operand of an arithmetic operator is not typed, XQuery attempts to cast it to a double. This cast may fail. This is exactly what XPath does, and it is also - as Joe points out - analogous to what TCL does. Of course, if datatypes are present, they are observed, unless the writer of the query explicitly casts data to something untyped. Jonathan
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