CODEWITHSUNDEEP
c#regex
Ege Bayrak
Ege Bayrak

Reputation: 1199

Regex for numbers after a certain string part

I'm trying to extract numbers inside an URL with regex. 

Example Input: http://localhost:23089/generic-url-segment-c?p=5

Expected Output : 5

Example Input: http://localhost:23089/generic-url-segment-c?p=12&sort=5

Expected Output: 12

First I tried to look for the numbers with a mixture of string.replace,string.indexof and substring but thought Regex would be easier.

So far I tried using ((p=)?=.) but can't get the 5 only.

And also as shown in second example, this value might be a two digit value or there even might be other parameters after it. So maybe a search between p= and & is necessary but I don't know how Regex behaves in absence of parameters.

Upvotes: 0

Views: 7683

Answers (2)

David Lindon
David Lindon

Reputation: 355

Try the below pattern. The plus matches 1 or more so you can get 1 or more digits -

 p=(\d+)

The brackets are a group so to get the value of the match within the group use 

match.Groups[1].Value

Upvotes: 3

Toto
Toto

Reputation: 91415

You could use lookbehind:

(?<=\bp=)\d+

or

(?<=[?&]p=)\d+

Usage:

Regex.Match(str, @"(?<=[?&]p=)\d+").Value;

Upvotes: 2

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