Regex doesn't find a match with a pattern

Question

In a C# project, Regex is behaving weirdly for me.

I have this method:

string RegTest()
    {
        string HTML = "<input type=\"hidden\" name=\"authenticity_token\" value=\"d27956cca6b75db4d8dd502d0569dd246455131c\">";
        Regex AuthRegex = new Regex(@"name=""authenticity_token"" value=""([A-Ba-b0-9/-]+)""");
        string Auth = AuthRegex.Match(HTML).Value;
        return Auth;
    }

For a reason I don't understand at all, the Regex doesn't find any match with this pattern. It just returns "".

How can I fix this?

@ndn I thought that by using @ I don't need to escape it. What is the correct way to escape it in the pattern? — BlueRay101
– BlueRay101, Commented Aug 29, 2015 at 12:18

ndnenkov · Accepted Answer · 2015-08-29 12:24:12Z

2

The problem is:

[A-Ba-b0-9/-]+

What character ranges (x-y) basically do is get a set of all characters in between. In other words, a-b = all letters between a and b, aka only a and b. However,

d27956cca6b75db4d8dd502d0569dd246455131c

looks like a hex. Therefore, you should use

[A-Fa-f0-9-]+

instead.

answered Aug 29, 2015 at 12:24

ndnenkov

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1 Comment

BlueRay101 Over a year ago

OK, Thank you very much! And now I've also noticed I wrote A-B instead of writing A-Z like I usually do... -_-

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