XSLT Reference
codepoints-to-string()
Constructs a string from a sequence of Unicode codepoint integers, enabling programmatic string assembly from character codes.
Syntax
codepoints-to-string(sequence)Description
codepoints-to-string() takes a sequence of integer Unicode codepoints and returns the string formed by the corresponding characters in that order. It is the inverse of string-to-codepoints().
This function is useful when you need to:
- Construct strings containing characters that are hard to type or embed in XML.
- Build strings programmatically from computed character codes.
- Round-trip through codepoint manipulation (e.g., ROT-13, Caesar cipher).
If the sequence is empty, the function returns an empty string. An error is raised if any integer in the sequence is not a valid XML character codepoint (e.g., codepoints in the surrogate range U+D800–U+DFFF).
Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
sequence | xs:integer* | Yes | A sequence of Unicode codepoint integers. |
Return value
xs:string — the string formed by concatenating the characters for each codepoint in order.
Examples
Building a string from 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="/">
<results>
<!-- Codepoints for 'Hello' -->
<word><xsl:value-of select="codepoints-to-string((72, 101, 108, 108, 111))"/></word>
<!-- Tab character (U+0009) -->
<tab-char><xsl:value-of select="codepoints-to-string(9)"/></tab-char>
<!-- Copyright sign (U+00A9) -->
<copyright><xsl:value-of select="codepoints-to-string(169)"/></copyright>
</results>
</xsl:template>
</xsl:stylesheet>
Output:
<results>
<word>Hello</word>
<tab-char> </tab-char>
<copyright>©</copyright>
</results>
Applying a simple character shift (Caesar cipher)
Input XML:
<?xml version="1.0" encoding="UTF-8"?>
<messages>
<msg>Hello</msg>
</messages>
Stylesheet:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xs="http://www.w3.org/2001/XMLSchema">
<xsl:output method="xml" indent="yes"/>
<xsl:function name="my:rot13" as="xs:string" xmlns:my="http://example.com/my">
<xsl:param name="s" as="xs:string"/>
<xsl:value-of select="codepoints-to-string(
for $cp in string-to-codepoints($s) return
if ($cp ge 65 and $cp le 90) then (($cp - 65 + 13) mod 26) + 65
else if ($cp ge 97 and $cp le 122) then (($cp - 97 + 13) mod 26) + 97
else $cp
)"/>
</xsl:function>
<xsl:template match="/messages">
<encoded>
<xsl:for-each select="msg">
<msg><xsl:value-of select="my:rot13(.)"/></msg>
</xsl:for-each>
</encoded>
</xsl:template>
</xsl:stylesheet>
Output:
<encoded>
<msg>Uryyb</msg>
</encoded>
Notes
- Codepoints must be valid XML characters. Codepoints 0 (except in some contexts), and the range U+D800–U+DFFF (surrogates) are not valid and will cause a dynamic error.
- The function accepts a single integer or a sequence of integers interchangeably.
- Combining with
string-to-codepoints()enables low-level string transformations without regular expressions. - Codepoint 32 is a space, 10 is a newline (
), 9 is a tab (	).