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Using regular expression on string for use in C#

I'm trying to extract a url from a string.
{ns:"images",k:"5127",mid:"A04F21EB77CF61E10E43BA33CF1986CA44357448"
,md5:"e2987d19c953bd836ec8fd2e0aa8492",surl:"http://someURLIdontwant/"
,imgurl:"http://THISISTHEURLINEED.jpg",tid:"OIP.Me2987d199c953bd836ec8fd2e0aa8492H0"
,ow:"300", docid:"608010036892077154",oh:"225",tft:"49"}
So it is located after "imgurl:". I am no expert on Regex and all I could produce is:
imgurl:'(.*)',tid
whitch worked on some online regex tester. But not the way I'm using it in C# apperantly.
webClient.DownloadFile(System.Text.RegularExpressions.Regex.Match
(stringWithText, "imgurl:'(.*)',tid").Groups[1].Value,"path\file.jpg");
Can it be done? Thanks

As #WiktorStribiżew already pointed out: The expression is almost correct. Use this instead:
Regex.Match(stringWithText, "imgurl:\"(.*)\",tid").Groups[1].Value
Example on dotNetFiddle
And as I mentioned earlier in a comment: You should parse the Json data instead.

C# Regex does not work in Javascript, MVC4, Custom RegularExpressionAttribute, IClientValidatable

I have a custom regular expression attribute which implements IClientValidate so that I can use it with unobtrustive validate.
When I run it I get the following error in FireBug
SyntaxError: Invalid quantifier
match = new RegExp(params).exec(value);
It obviously does not like the regular expression that is passed to it, it is valid in C#. I can't seem to work out what I need to do to get it to be valid in JavaScript.
The regex is
^(?i)([A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]?\s?[0-9][ABD-HJLN-UW-Z]{2})$

The JavaScript regex flavor is extremely limited compared to .NET (C#). One of the many features it doesn't support is inline modifiers of the form (?i)regex or (?i:regex). However, because you're using the new RegExp(params) constructor, you should be able to pass the modifier as the second parameter:
"^[A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]?\s?[0-9][ABD-HJLN-UW-Z]{2}$",
"i"

Replace (?i) by i modifier:
var patt=/^([A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]?\s?[0-9][ABD-HJLN-UW-Z]{2})$/i

When i run your regex in this : http://regexpal.com/
I get error on this part : (?i)
Rexegpal is a JavaScript regular expression tester.
So if you can get it to work here you can then apply it in your code.
Perhaps you have some example string to try with?

Regex Regular expression in c#

We have implemented the invocation of brill tagger from our c# code. We just neede to know what is the correct Regex regular expression for eliminating all from a string, but jst keep a-z,A-Z, full stop and comma. We tried [^a-zA-Z\.\,] on the online regular expression tester and it is giving the correct result, but when implemented in C#, it is not working properly. We also tried several other combinations but we are not getting the correct result.
This is the format in which we are writing:
strFileContent = Regex.Replace(strFileContent, #"[^a-zA-Z\.\,]", "");
but we are not getting the desired output. what is wrong??

Regex.Replace(yourString, #"[^a-z\.\,]", string.Empty, RegexOptions.IgnoreCase)
EDIT: I can't see anything wrong with what you are doing, my answer is exactly the same. I tested both in LINQPad and they both return the same result.

What is C# equivalent of preg_match_all?

The theme is i opened a file and get all it's data into string and i am matching this string with the regex returning none. But the same regex in PHP is returning values for the same text using preg_match_all. Anyone having a idea?

The method in .NET that’s closest to preg_match_all() is the static Regex.Matches(String,String) call, or the equivalent Matches method on a compiled regular expression. It returns a MatchCollection that you can use to count the matches and to loop over each one.
Can you provide some short, self-contained code to show what’s not working?

There is a Regex.Matches method in C# that you can use.

Regex index in matching string where the match failed

I am wondering if it is possible to extract the index position in a given string where a Regex failed when trying to match it?
For example, if my regex was "abc" and I tried to match that with "abd" the match would fail at index 2.
Edit for clarification. The reason I need this is to allow me to simplify the parsing component of my application. The application is an Assmebly language teaching tool which allows students to write, compile, and execute assembly like programs.
Currently I have a tokenizer class which converts input strings into Tokens using regex's. This works very well. For example:
The tokenizer would produce the following tokens given the following input = "INP :x:":
Token.OPCODE, Token.WHITESPACE, Token.LABEL, Token.EOL
These tokens are then analysed to ensure they conform to a syntax for a given statement. Currently this is done using IF statements and is proving cumbersome. The upside of this approach is that I can provide detailed error messages. I.E
if(token[2] != Token.LABEL) { throw new SyntaxError("Expected label");}
I want to use a regular expression to define a syntax instead of the annoying IF statements. But in doing so I lose the ability to return detailed error reports. I therefore would at least like to inform the user of WHERE the error occurred.

I agree with Colin Younger, I don't think it is possible with the existing Regex class. However, I think it is doable if you are willing to sweat a little:
Get the Regex class source code
(e.g.
http://www.codeplex.com/NetMassDownloader
to download the .Net source).
Change the code to have a readonly
property with the failure index.
Make sure your code uses that Regex
rather than Microsoft's.

I guess such an index would only have meaning in some simple case, like in your example.
If you'll take a regex like "ab*c*z" (where by * I mean any character) and a string "abbbcbbcdd", what should be the index, you are talking about?
It will depend on the algorithm used for mathcing...
Could fail on "abbbc..." or on "abbbcbbc..."

I don't believe it's possible, but I am intrigued why you would want it.

In order to do that you would need either callbacks embedded in the regex (which AFAIK C# doesn't support) or preferably hooks into the regex engine. Even then, it's not clear what result you would want if backtracking was involved.

It is not possible to be able to tell where a regex fails. as a result you need to take a different approach. You need to compare strings. Use a regex to remove all the things that could vary and compare it with the string that you know it does not change.
I run into the same problem came up to your answer and had to work out my own solution. Here it is:
https://stackoverflow.com/a/11730035/637142
hope it helps