3.9. Retrieve Part of the Matched Text
Problem
As in Recipe 3.7, you have a regular expression that matches a substring of the subject text, but this time you want to match just one part of that substring. To isolate the part you want, you added a capturing group to your regular expression, as described in Recipe 2.9.
For example, the regular expression ‹http://([a-z0-9.-]+)
› matches http://www.regexcookbook.com
in the string
Please visit
http://www.regexcookbook.com for more information
. The part
of the regex inside the first capturing group matches www.regexcookbook.com
, and
you want to retrieve the domain name captured by the first capturing
group into a string variable.
We’re using this simple regex to illustrate the concept of capturing groups. See Chapter 8 for more accurate regular expressions for matching URLs.
Solution
C#
For quick one-off matches, you can use the static call:
string resultString = Regex.Match(subjectString, "http://([a-z0-9.-]+)").Groups[1].Value;
To use the same regex repeatedly, construct a Regex
object:
Regex regexObj = new Regex("http://([a-z0-9.-]+)"); string resultString = regexObj.Match(subjectString).Groups[1].Value;
VB.NET
For quick one-off matches, you can use the static call:
Dim ResultString = Regex.Match(SubjectString, "http://([a-z0-9.-]+)").Groups(1).Value
To use the same regex repeatedly, construct a Regex
object:
Dim RegexObj As New Regex("http://([a-z0-9.-]+)") Dim ResultString = RegexObj.Match(SubjectString).Groups(1).Value
Java
String resultString ...
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