xslt-lab/site/content/xslt/functions/xpath-starts-with.md

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

title	description	date	version	versionLabel	category	syntax	tags
starts-with()	Returns true if the first string begins with the second string as an exact prefix, performing a case-sensitive comparison.	2026-04-18T00:00:00Z	1.0	XSLT 1.0	string function	starts-with(string, prefix)	xslt reference xpath xslt1

Description

starts-with() tests whether string begins with prefix and returns a boolean. Both arguments are converted to strings before the comparison, which is case-sensitive and based on Unicode code points.

If prefix is the empty string "", the function always returns true, because every string (including the empty string) starts with the empty string.

starts-with() is commonly used in predicates to select elements or attributes that share a naming convention, a URL scheme prefix, or any other known leading text. It is simpler and faster than the equivalent substring() comparison.

Parameters

Parameter	Type	Required	Description
string	xs:string	Yes	The string to test.
prefix	xs:string	Yes	The expected prefix.

Return value

xs:boolean — true if string starts with prefix, false otherwise.

Examples

Filter elements by attribute prefix

Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<links>
  <link href="https://example.com/page1">Page 1</link>
  <link href="http://example.com/page2">Page 2</link>
  <link href="https://example.com/page3">Page 3</link>
  <link href="ftp://files.example.com">Files</link>
</links>

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="/links">
    <secure-links>
      <xsl:for-each select="link[starts-with(@href, 'https://')]">
        <a href="{@href}"><xsl:value-of select="."/></a>
      </xsl:for-each>
    </secure-links>
  </xsl:template>
</xsl:stylesheet>

Output:

<secure-links>
  <a href="https://example.com/page1">Page 1</a>
  <a href="https://example.com/page3">Page 3</a>
</secure-links>

Conditional processing based on prefix

Input XML:

<?xml version="1.0" encoding="UTF-8"?>
<codes>
  <code>ERR-001</code>
  <code>OK-202</code>
  <code>ERR-403</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">
    <report>
      <xsl:for-each select="code">
        <xsl:if test="starts-with(., 'ERR')">
          <error><xsl:value-of select="."/></error>
        </xsl:if>
      </xsl:for-each>
    </report>
  </xsl:template>
</xsl:stylesheet>

Output:

<report>
  <error>ERR-001</error>
  <error>ERR-403</error>
</report>

Notes

• The comparison is case-sensitive: starts-with('Hello', 'he') returns false. For case-insensitive prefix matching in XSLT 2.0+, use starts-with(lower-case($s), 'he').
• starts-with($s, '') always returns true.
• XPath 1.0 has no ends-with() function. To test a suffix, use substring($s, string-length($s) - string-length($suffix) + 1) = $suffix, or use ends-with() in XSLT 2.0+.
• starts-with() is equivalent to substring($s, 1, string-length($prefix)) = $prefix but far more readable.

See also

• contains()
• substring-before()
• substring-after()