.Net C# regex for parsing URL parameters

Question

I need to parse a string, such as /a/b/c/d=uno/c=duo.html

into three groups, such as

• /a/b/c/
• d=uno/
• c=duo.html

The parsing rules are:

1. The first group is everything until "d=" or the whole string if "d=" is not a part of the string.
2. The second group is everything until "c=" or the rest of the string following the first group if "c=" is not a part of the string.
3. The third group matches the rest of the string following the second group.

My problem with the following regex (?.+/)?(?d=([^/]+)/)?(?c=(?.*)) is that I don't know how to stop the group when it encounters "d=".

Any help will be appreciated.

Thanks.

Answer 1

Is the string you need to parse in the form you supplied, or is it an actual URL with parameters? If it's a URL, you can use System.Web.HttpUtility.ParseQueryString to extract a NameValueCollection containing each parameter and its value.

I've found this useful even in Windows Forms (eg parsing query parameters in ClickOnce deployed applications).

Answer 2

The string is in the format I supplied, not a URL. It's a custom repository location format.

Answer 3

(.*?)(?>d=|$)(.*?)(?>c=|$)(.*?)$

group1: Everything till d= or end of string

group2: Everything till c= or end of string

group3: Everything till end of string

Answer 4

RegEx suggested by hasankhan works great.

How can I extend this regex to require group1 and group2 to end with a slash?

For example, matching should succeed on the following valid strings:

• /a/b/c/
• /a/b/c/d=uno/

but should fail when matching either of these:

• /a/b/c
• /a/b/c/d=uno

Thank you for your help.

Answer 5

(.*?/)(?>d=|$)(.*?/)(?>c=|$)(.*?)$