Return substring of a string value.

Related Syntax Constructs

The following construct(s) refer to this construct:

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Syntax

fn:substring(string $string, double $position) => string?

fn:substring(string $string, double $position, double $length) => string?

Description

This function returns that part of $string, which begins at $position and is the number of characters indicated by length. More precisely, the function returns the characters in $string, whose position $p satisfies:

fn:round($position) <= $p < fn:round($position) + fn:round($length)

The following rules hold:

• If $length is not specified or if $length is greater than the number of characters in the value of $string following $position, the substring includes characters to the end of $string.

• If $position is zero or negative, the substring includes characters from the beginning of the $string.

• It is an error if $string is the empty sequence.

Argument

$string	string value
$position	double value: the position at which the search takes place
$length	double value: the length of the substring

Examples

• Both queries below return " XML":

  substring("Tamino XML Server", 7, 4)
  substring("Tamino XML Server", 6.5, 4.4)

  Like the first query, the second one looks for four characters beginning at position 7.

• Return the second half of the specified string:

  let    $text := "Tamino XML Server"
  return substring($text, string-length($text) div 2)