Re: [xsl] XPath string comparison of two strings representing calendar d

The values are not directly parseable as xs:date or xs:dateTime values, so I 
think you’ll have to preprocess them to make proper date strings out of them 
and compare them as dates(), e.g.:

local:makeDate(/Test/Date2) gt local:makeDate(/Test/Date1)

Where I leave local:makeDate() as an exercise to the reader (

Cheers,

Eliot
--
Eliot Kimber
http://contrext.com
 


On 8/16/17, 11:09 AM, "Costello, Roger L. costello(_at_)mitre(_dot_)org" 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

    Hi Folks,
    
    I have an XML document that contains two elements with values representing 
calendar dates, in YYYYMMDD format, e.g.,
    
    <Test>
        <Date1>20170816</Date1>
        <Date2>20170817</Date2>
    </Test>
    
    This is the format that iCalendar (RFC 5545) uses to represent dates.
    
    I wish to test to see if the calendar date represented in <Date2> is 
greater than (occurs later in chronological time) the calendar date represented 
in <Date1>. Here's an XPath expression to do the test:
    
    /Test/Date2 gt /Test/Date1
    
    In this case, the XPath returns true.
    
    Note that I am doing mere string comparison. I am comparing the string 
'20170817' against the string '20170816'.
    
    Will the XPath always work? 
    
    Is there a counterexample, where <Date2> holds a value representing a 
calendar date that is less than (occurs earlier in chronological time) the 
calendar date represented in <Data1>, and yet the XPath returns true? 
    
    If there is a counterexample, what XPath expression will always work?
    
    /Roger
    
    
    
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