xslt-lab/site/content/xslt/functions/xpath-substring.md

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

title	description	date	version	versionLabel	category	syntax	tags
substring()	Extracts a portion of a string by start position and optional length, returning the resulting substring.	2026-04-18T00:00:00Z	1.0	XSLT 1.0	string function	substring(string, start, length?)	xslt reference xslt1 xpath

Description

substring() returns the portion of a string beginning at position start and extending for length characters. If length is omitted, the function returns all characters from start to the end of the string.

String positions in XPath are 1-based (the first character is position 1). The start and length arguments are numbers; they are rounded to the nearest integer using the XPath rounding rules. If start is less than 1, the returned string effectively begins at position 1 (the excess is deducted from length).

substring() is the fundamental string-slicing function in XPath 1.0. For more complex extraction needs, consider substring-before() and substring-after(), which split on a delimiter without needing to know its position.

Parameters

Parameter	Type	Required	Description
string	xs:string	Yes	The source string to extract from.
start	xs:double	Yes	1-based position of the first character to include.
length	xs:double	No	Number of characters to include. Defaults to the rest of the string.

Return value

xs:string — the extracted substring.

Examples

Extract a fixed-length prefix

Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<codes>
  <code>PROD-001-RED</code>
  <code>PROD-002-BLU</code>
  <code>PROD-003-GRN</code>
</codes>

Stylesheet:

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

  <xsl:template match="/codes">
    <ids>
      <xsl:for-each select="code">
        <!-- Extract characters 6 to 8 (the numeric ID) -->
        <id><xsl:value-of select="substring(., 6, 3)"/></id>
      </xsl:for-each>
    </ids>
  </xsl:template>
</xsl:stylesheet>

Output:

<ids>
  <id>001</id>
  <id>002</id>
  <id>003</id>
</ids>

Extract from a position to end of string

Stylesheet:

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

  <xsl:template match="/codes">
    <colors>
      <xsl:for-each select="code">
        <!-- Skip first 9 characters, get the rest -->
        <color><xsl:value-of select="substring(., 10)"/></color>
      </xsl:for-each>
    </colors>
  </xsl:template>
</xsl:stylesheet>

Output:

<colors>
  <color>RED</color>
  <color>BLU</color>
  <color>GRN</color>
</colors>

Capitalise first character (XSLT 2.0 pattern)

<!-- Uppercase the first character, lowercase the rest -->
<xsl:value-of select="concat(upper-case(substring(name, 1, 1)), lower-case(substring(name, 2)))"/>

Notes

• XPath string positions start at 1, not 0. substring('hello', 1, 3) returns "hel".
• If start + length exceeds the string length, the result is simply truncated at the end of the string — no error is raised.
• For delimiter-based splitting, substring-before() and substring-after() are more convenient than computing numeric positions.
• In XSLT 2.0+, replace() with regex groups is often a cleaner way to extract structured parts of strings.

See also

• contains()
• replace()