xslt-lab/site/content/xslt/functions/xpath-string-to-codepoints.md

title, description, date, version, versionLabel, category, syntax, tags

title	description	date	version	versionLabel	category	syntax	tags
string-to-codepoints()	Returns a sequence of integers representing the Unicode codepoints of each character in a string.	2026-04-18T00:00:00Z	2.0	XSLT 2.0	string function	string-to-codepoints(string)	xslt reference xslt2 xpath

Description

string-to-codepoints() decomposes a string into its individual Unicode characters and returns their integer codepoints as a sequence of xs:integer values. The sequence length equals the number of Unicode characters (codepoints) in the string, which may differ from the byte length in UTF-8 or UTF-16 encodings.

It is the inverse of codepoints-to-string() and enables character-level manipulation — inspecting, filtering, or transforming individual characters by their numeric values.

If the argument is an empty sequence or an empty string, the function returns an empty sequence.

Parameters

Parameter	Type	Required	Description
string	xs:string?	Yes	The string to decompose into codepoints.

Return value

xs:integer* — a sequence of Unicode codepoint integers, one per character.

Examples

Inspecting character codepoints

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/">
    <codepoints>
      <xsl:for-each select="string-to-codepoints('Hello!')">
        <cp value="{.}"/>
      </xsl:for-each>
    </codepoints>
  </xsl:template>
</xsl:stylesheet>

Output:

<codepoints>
  <cp value="72"/>
  <cp value="101"/>
  <cp value="108"/>
  <cp value="108"/>
  <cp value="111"/>
  <cp value="33"/>
</codepoints>

Filtering non-ASCII characters

Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<texts>
  <text>Héllo Wörld</text>
  <text>Plain ASCII only</text>
</texts>

Stylesheet:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" indent="yes"/>

  <xsl:template match="/texts">
    <analysis>
      <xsl:for-each select="text">
        <xsl:variable name="cps" select="string-to-codepoints(.)"/>
        <text ascii-only="{if (every $cp in $cps satisfies $cp le 127) then 'yes' else 'no'}">
          <xsl:value-of select="."/>
        </text>
      </xsl:for-each>
    </analysis>
  </xsl:template>
</xsl:stylesheet>

Output:

<analysis>
  <text ascii-only="no">Héllo Wörld</text>
  <text ascii-only="yes">Plain ASCII only</text>
</analysis>

Notes

• Each item in the returned sequence is the codepoint of one Unicode character, not one byte. For multi-byte UTF-8 characters (e.g., © is 2 bytes) the function still returns one integer.
• Surrogate pairs as used in UTF-16 are presented as their actual codepoint (e.g., U+1F600 emoji returns 128512, not two surrogate integers).
• Combining with codepoints-to-string() allows lossless character-by-character transformations.
• count(string-to-codepoints($s)) gives the number of Unicode characters, equivalent to string-length($s).

See also

• codepoints-to-string()
• string-length()
• normalize-unicode()