Name
substring — Returns the substring of the first argument starting at the position specified in the second argument with length specified in the third argument.
Synopsis
string substring ( |
strg string , |
| start integer , | |
length integer ); |
Description
The substring() XPATH function returns the substring of the
strg starting at the
position specified in start
argument with length specified in length argument. If length is not specified, it returns
the substring starting at the position specified in the start argument and continuing to the
end of the string.
XPATH 1.0 defines that "each character in the string... is
considered to have a numeric position: the position of the first
character is 1, the position of the second character is 2 and so
on. This differs from Java and ECMAScript, in which the
String.substring method treats the position of the first character
as 0." The returned substring contains those characters for which
the position of the character is greater than or equal to
start and, if length is specified, less than the
sum of start and length .
If start and/or
length are not integers,
they are converted to integers following rules for round() XPATH
function, before doing any other processing. So they will be
rounded first, and the sum of rounded values will be used as "end
position"
If start is greater than
or equal to the length of string, the empty string is returned. If
length is specified and the
sum of start is less than
or equal to 1, the empty string is returned, too. Otherwise, the
result string will contains some characters even if start is less than 1.
If length start is greater than or equal to the
length of string, the empty string is returned.
Parameters
strg
Source string. If the argument is not a string, it is converted to string first.
start
Position of first character of the substring in the source string.
length
Number of characters in the substring, if specified.
Return Types
String
Examples
Example24.623.
The following expressions are all true:
substring("12345", 2, 3) = "234"
substring("12345", 2) = "2345"
substring("12345", 1.5, 2.6) = "234"
substring("12345", 0, 3) = "12"
substring("12345", -2, 5) = "12"
substring("12345", -2) = "12345"