[xsl] Re: comparing strings

[Dimitre Novatchev <dnovatchev@xxxxxxxxx>]

Hi Oliver,

Here's a solution that does not limit the two strings to contain only
Latin characters. It can be further parameterised to accept as
parameters any of the useful <xsl:sort> attributes. 

Let's not forget that there are different rules for comparing
characters in different languages and there isn't an universal rule for
character comparison. I guess this fact was one of the reasons not to
provide (inequality) string comparison operators in XPath.

The node-set() extension function has to be used -- however it will be
standard in XSLT 1.1.

The example stylesheet below calls the template named "stringCompare"
with the following parameters:

str1 = 'Paris'
str2 = 'London'

The result is:
'Paris' is greater than 'London'

Dimitre Novatchev.

stringCompare.xsl:
-----------------
<xsl:stylesheet version='1.0'
xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
xmlns:msxsl="urn:schemas-microsoft-com:xslt" 
>

<xsl:output method="text"/>

<xsl:template match="/">
  <xsl:text>'Paris'</xsl:text>
	
  <xsl:text> is</xsl:text>
  <xsl:call-template name="stringCompare">
    <xsl:with-param name="str1" select="'Paris'"/>
    <xsl:with-param name="str2" select="'London'"/>
  </xsl:call-template>
  <xsl:text>'London'</xsl:text>
</xsl:template>

<xsl:template name="stringCompare">
  <xsl:param name="str1"/>
  <xsl:param name="str2"/>
	
  <xsl:choose>
    <xsl:when test="str1=str2">
      <xsl:text> equal </xsl:text>
    </xsl:when>
    <xsl:otherwise>
      <xsl:variable name="thePair">
        <xsl:element name="str1">
          <xsl:value-of select="$str1"/>
        </xsl:element>
        <xsl:element name="str2">
          <xsl:value-of select="$str2"/>
        </xsl:element>
      </xsl:variable>
      <xsl:variable name="sortedPair">	
        <xsl:for-each select="msxsl:node-set($thePair)/*">	
          <xsl:sort select="."/>	
          <xsl:copy-of select="."/>
        </xsl:for-each>		
      </xsl:variable>
			
      <xsl:choose>
        <xsl:when test="$str1 = msxsl:node-set($sortedPair)/*[1]">
          <xsl:text> less than </xsl:text>
        </xsl:when>
        <xsl:otherwise>
          <xsl:text> greater than </xsl:text>
        </xsl:otherwise>
      </xsl:choose>
    </xsl:otherwise>
  </xsl:choose>
	
</xsl:template>
</xsl:stylesheet>

 
result:
------
'Paris' is greater than 'London'


Oliver Becker wrote:

Is there someone out there who can answer my simple question:
How to compare strings with XPath/XSLT, something like strcmp() in C
or compareTo() in Java?
I want a pure XSLT solution without using extensions.




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