CODEWITHSUNDEEP
.netregex
John
John

Reputation: 762

match start of string

I have some "paths" that are in a format similar to:

/Media/Default/images/Tulips.jpg

And I have the ability to get the "root path" which will return something similar to either:

http://example.com/Media/Default/
/another-prefix/Media/Default/

what I need to do is match the start of the "path" string with the end of "root path" string to return images/Tulips.jpg

What i really need is a generic regular expression that will compare pare the 2 strings do a sort of an overlay and trim at the greatest possible match. That way it will work if the inputs were changed to:

Path: qwerty-some-random-string

Root Path: junk-qwerty

Result: -some-random-string

Upvotes: 1

Views: 161

Answers (1)

Jon
Jon

Reputation: 437386

Correct solution (with LINQ)

Tries all suffixes of root in descending order of length and stops when it determines that one of them is a prefix of path:

var path = "qwerty-qwerty-some-random-string";
var root = "aardvark-junk-qwerty-qwerty";

var prefix = root.Select((ch, i) => root.Substring(i))
                 .Where(pref => path.StartsWith(pref))
                 .DefaultIfEmpty("")
                 .First();
var result = path.Substring(prefix.Length);

See it in action.

Note: Initially I posted a regex solution here but it turned out that it was completely unworkable.

Upvotes: 2

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