c# - Regex for numbers after a certain string part

Question

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.

Answer 1

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