XPath Datatypes
An XPath expression returns one of four datatypes:
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node-set Represents a set of nodes. The set can be empty, or it can contain any number of nodes.
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boolean Represents the value
trueorfalse. Be aware that thetrueorfalsestrings have no special meaning or value in XPath; see Section 4.2.1.2 in Chapter 4 for a more detailed discussion of boolean values.-
number Represents a floating-point number. All numbers in XPath and XSLT are implemented as floating-point numbers; the
integer(orint) datatype does not exist in XPath and XSLT. Specifically, all numbers are implemented as IEEE 754 floating-point numbers, the same standard used by the Javafloatanddoubleprimitive types. In addition to ordinary numbers, there are five special values for numbers: positive and negative infinity, positive and negative zero, andNaN, the special symbol for anything that is not a number.-
string Represents zero or more characters, as defined in the XML specification.
These datatypes are usually simple, and with the exception of node-sets, converting between types is usually straightforward. We won’t discuss these datatypes in any more detail here; instead, we’ll discuss datatypes and conversions as we need them to do specific tasks.