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Asked: 2026-05-30T01:23:19+00:00

<xsl:template match=/> <xsl:variable name=a select=’a’/> <xsl:variable name=b select=’b’/> <xsl:variable name=c select=’c’/> <xsl:variable name=result> <xsl:choose>

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<xsl:template match="/">
      <xsl:variable name="a" select="'a'"/>
      <xsl:variable name="b" select="'b'"/>
      <xsl:variable name="c" select="'c'"/>
      <xsl:variable name="result">
        <xsl:choose>
          <xsl:when test="$a !=''">
            <xsl:value-of select="$a"/>
          </xsl:when>
          <xsl:when test="$b !=''">
            <xsl:value-of select="$b"/>
          </xsl:when>
          <xsl:otherwise>
            <xsl:value-of select="$c"/>
          </xsl:otherwise>
        </xsl:choose>
      </xsl:variable>

The result variable is populated, here i used the xsl choose statements. I just wanted to know if there is any other efficient or simple way to populate the result variable, based on the same logic as xsl choose.

Something like this

<xsl:variable name="result" select="$a | $b | $c" />

The above will work for nodesets, not for variables. Any inputs?xsl 1.0

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1 Answer

  1. Editorial Team

    Something like this

    <xsl:variable name="result" select="$a | $b | $c" />

    The above will work for nodesets, not for variables. Any inputs?xsl
    1.0

    This is wrong! The above result variable is defined to contain the union of three node-sets — not just one of them, depending on whether some other(s) of them are empty.

    A correct XPath expression in this case is:

    $a | $b[not($a)] | $c[not($a | $b)]

    When These three variables aren’t node-sets but strings and if these string values can have any length (not only length of 1), the corresponding XPath expression is similar:

    concat($a, 
       substring($b, 1 div ($a = '')), 
       substring($c, 1 div (concat($a, $b) = ''))
       )

    Here we use the fact that:

    substring($s, $k) is the empty string ''

    whenever 

    $k >= string-length($s)

    and

    substring($s, 1) = $s

    Also:

    1 div false()

    is positive Infinity

    (false() is converted to 0 when used in arithmetic operations).

    and by definition 

    positive Infinity > $k

    for every integer $k.

    Therefore,

    substring($s, 1 div $somethingFalse) = ''

    and

    substring($s, 1 div $somethingTrue) = $s

    Finally, if it is guaranteed that the three variables $a, $b and $c can have as value only a single character, than we can use just:

    substring(concat($a, $b, $c), 1, 1)
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