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Sorting

By default, XSLT processes nodes in document order — the order they appear in the source. xsl:sort overrides that, reordering the nodes a for-each or apply-templates is about to process.

xsl:sort

Place xsl:sort as the first child of the loop. It does not output anything itself; it reorders the iteration.

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<xsl:for-each select="catalog/cd">
  <xsl:sort select="artist"/>          <!-- (1)! -->
  <p>
    <xsl:value-of select="artist"/> — <xsl:value-of select="title"/>
  </p>
</xsl:for-each>
  1. Sort the CDs by their <artist> child before iterating.

Sorting the catalog by artist:

Bob Dylan — Empire Burlesque

Bonnie Tyler — Hide your heart

Dolly Parton — Greatest Hits

Controlling the sort

xsl:sort takes several attributes:

Attribute Values Effect
select XPath The key to sort on (default: the node's string value)
order ascending (default), descending Direction
data-type text (default), number Compare as strings or numerically
case-order upper-first, lower-first Tie-break for mixed case

The data-type distinction matters. As text, "9.90" sorts after "10.90" because "9" > "1" character-wise. To order by price correctly, sort numerically:

<xsl:sort select="price" data-type="number" order="descending"/>

Empire Burlesque — 10.90

Hide your heart — 9.90

Greatest Hits — 9.90

Multiple keys

Several xsl:sort elements act as successive tie-breakers, in order. This sorts by price descending, then by title for CDs at the same price:

<xsl:for-each select="catalog/cd">
  <xsl:sort select="price" data-type="number" order="descending"/>
  <xsl:sort select="title"/>
  ...
</xsl:for-each>

The same xsl:sort works inside xsl:apply-templates when you let the processor drive iteration:

<xsl:apply-templates select="catalog/cd">
  <xsl:sort select="artist"/>
</xsl:apply-templates>

Next

That covers the core transformation toolkit. The remaining pages collect techniques you reach for in larger, real-world stylesheets — starting with number formatting for money and locale-aware output.