Regular expressions

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Darwin - 24 Mar 2008 21:28 GMT

Hi,
I am trying to extract the host name from a HTTP header:
GET /1/1/typical.php HTTP/1.1
Accept: image/gif, image/x-xbitmap, image/jpeg, image/pjpeg,
application/x-shockwave-flash, */*
Referer: http://www.httphost.com/1/1/
Accept-Language: en-us
UA-CPU: x86
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR
1.1.4322; .NET CLR 2.0.50727)
Host: www.httphost.com
Connection: Keep-AliveSo I just want to extract the text www.httphost.com
from the above. My code is below:
Regex r = new Regex(@"Host: ([A-Za-z0-9_:.]+)$", RegexOptions.Multiline);

// Match the regular expression pattern against a text string.

Match m = r.Match(message.ToString());

MessageBox.Show(m.Value);

But it shows a blank, I am sure there is an obvious answer.

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Gilles Kohl [MVP] - 24 Mar 2008 22:00 GMT

>Hi,
>I am trying to extract the host name from a HTTP header:
[quoted text clipped - 19 lines]
>
>But it shows a blank, I am sure there is an obvious answer.

Hmm, can you post a complete snippet of code? (e.g. a self-contained method)
What is message, and what is its exact contents?

What does m.Success contain?

Regards,
Gilles.

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schoensy - 24 Mar 2008 22:07 GMT

> Hi,
> I am trying to extract the host name from a HTTP header:
[quoted text clipped - 19 lines]
>
> But it shows a blank, I am sure there is an obvious answer.

I was able to validate that the following regexp works, but I haven't
run it through the code you wrote to see what the result is. Just
winging it, here's how I would write it out:

Match m = new Regex.Match(message.ToString(), @"Host: ([\w\.\-:_]*)");
MessageBox.Show(m.Value);

Hope that helps.

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Darwin - 24 Mar 2008 23:04 GMT

Thanks for the help here's what I ended up with (appropriate error checks to
be implemented) :

Regex r = new Regex(@"Host: ([\w\.\-:_]*)", RegexOptions.Multiline);

Match m = r.Match(message.ToString());

if (m.Length > 0)

{

MessageBox.Show(m.Groups[1].Value);

}

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Regular expressions

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