Develop Reference

Regex to Replace the end of the Url

I have a url something that follows a pattern as below :
http://i.ebayimg.com/00/s/MTUw12323gxNTAw/$(KGr123qF,!p0F123Q~~60_12.JPG?set_id=88123231232F
I need a regex to find and replace the end of the url _12.JPG with _14.JPG. So basically i need to capture the _[numbers only].JPG pattern and replace it with my value.

var regex = new Regex(#"_\d+\.JPG");
var newUrl = regex.Replace(url, "_14.JPG");

_[0-9]+\.JPG\?
works for the sample URL. You didn't really mention whether you wanted the
?set_id=88123231232F gone or not.

Basically, you shouldn't normally be concerned with periods anywhere else in the URL. It is possible, but the additional constraint of the jpg extension should limit anything returned with not much issue.
///_(\d?\d).jpg/ig
var regex = new Regex(#"_(\d?\d).[Jj][Pp][Gg]");
That will capture one or two numbers between an underscore and .jpg
I will double check this, but it should work for both one digit and two digits.

Correction in this simple regular expression

I am new to regular expressions and the one that i have written might be a very simple one but donot know where I am wrong.
#"^([a-zA-Z._]+)#([\d]+)"
This RE is for the following string:
somename#somenumber
Now i am trying to retrieve the somename and somenumber. This is what i did:
ac.name = m.Groups[0].Value;
ac.number = m.Groups[1].Value;
Here ac.name reads the complete string, and ac.number reads somenumber. Where am I wrong in ac.name?

i guess the regex is correct, the problem is, you get the ac.name not from group 1 but group(0), which is the whole string. try this:
ac.name = m.Groups[1].Value;
ac.number = m.Groups[2].Value;

This regex is correct. I think your mistake is in somewhere else. You seem to use C#. So, you should think about the regex usage in the language.
Looking to the code sample in MSDN, you need to use 1-based indexes while accessing Groups instead of zero-based (as also Kent suggested). So, use this:
String name = m.Groups[1].Value;
String number = m.Groups[2].Value;

use this regex (\w+)#(\d+([.,]\d+)?)
Groups[1] will be contain name
Groups[2] will be contain number

I think you should move the + into the capture group:
#"^([a-zA-Z._]+)#([\d]+)"

If this is C#, try without the ^
([a-zA-Z\._]+)#([\d]+)
I just tried it out and it groups properly
Update: escaped the .
If you want only one match (and hence the ^ in original expression), use .Match instead of .Matches method. See MSDN documentation on Regular Expression Classes.

URL regex - not getting it to work

I am using the following regex to find if there is a url present in a text, however it seems to miss some URLs like:
youtube.be/8P0BxJO
youtube.com/watch?v=VrmlFL
and also some bit.ly links (but not all)
Match m = Regex.Match(nc[i].InnerText,
#"(http(s)?://)?([\w-]+\.)+[\w-]+(/\S\w[\w- ;,./?%&=]\S*)?");
if (m.Success)
{
MessageBox.Show(nc[i].InnerText);
}
any ideas how to fix it?

See this related question, the first answer should help you out. The suggestion both finds links and then replaces them, so obviously just take what you need. This and this article are different approaches that should get you more or less the same result.
Another (perhaps more reliable) non-regex approach would be to tokenize the string by splitting on spaces and punctuation, and then checking the tokens to see whether they are a valid uri using Uri.IsWellFormedUriString (which only works on well formed uri's, as this question points out).

Regular expression for recognizing url

I want to create a Regex for url in order to get all links from input string.
The Regex should recognize the following formats of the url address:
http(s)://www.webpage.com
http(s)://webpage.com
www.webpage.com
and also the more complicated urls like:
- http://www.google.pl/#sclient=psy&hl=pl&site=&source=hp&q=regex+url&pbx=1&oq=regex+url&aq=f&aqi=g1&aql=&gs_sm=e&gs_upl=1582l3020l0l3199l9l6l0l0l0l0l255l1104l0.2.3l5l0&bav=on.2,or.r_gc.r_pw.&fp=30a1604d4180f481&biw=1680&bih=935
I have the following one
((www\.|https?|ftp|gopher|telnet|file|notes|ms-help):((//)|(\\\\))+[\w\d:##%/;$()~_?\+-=\\\.&]*)
but it does not recognize the following pattern: www.webpage.com. Can someone please help me to create an appropriate Regex?
EDIT:
It should works to find an appropriate link and moreover place a link in an appropriate index like this:
private readonly Regex RE_URL = new Regex(#"((https?|ftp|gopher|telnet|file|notes|ms-help):((//)|(\\\\))+[\w\d:##%/;$()~_?\+-=\\\.&]*)", RegexOptions.Multiline);
foreach (Match match in (RE_URL.Matches(new_text)))
{
// Copy raw string from the last position up to the match
if (match.Index != last_pos)
{
var raw_text = new_text.Substring(last_pos, match.Index - last_pos);
text_block.Inlines.Add(new Run(raw_text));
}
// Create a hyperlink for the match
var link = new Hyperlink(new Run(match.Value))
{
NavigateUri = new Uri(match.Value)
};
link.Click += OnUrlClick;
text_block.Inlines.Add(link);
// Update the last matched position
last_pos = match.Index + match.Length;
}

I don't know why your result in match is only http:// but I cleaned your regex a bit
((?:(?:https?|ftp|gopher|telnet|file|notes|ms-help):(?://|\\\\)(?:www\.)?|www\.)[\w\d:##%/;$()~_?\+,\-=\\.&]+)
(?:) are non capturing groups, that means there is only one capturing group left and this contains the complete matched string.
(?:(?:https?|ftp|gopher|telnet|file|notes|ms-help):(?://|\\\\)(?:www\.)?|www\.) The link has now to start with something fom the first list followed by an optional www. or with an www.
[\w\d:##%/;$()~_?\+,\-=\\.&] I added a comma to the list (otherwise your long example does not match) escaped the - (you were creating a character range) and unescaped the . (not needed in a character class.
See this here on Regexr, a useful tool to test regexes.
But URL matching is not a simple task, please see this question here

I've just written up a blog post on recognising URLs in most used formats such as:
www.google.com
http://www.google.com
mailto:somebody#google.com
somebody#google.com
www.url-with-querystring.com/?url=has-querystring
The regular expression used is /((([A-Za-z]{3,9}:(?:\/\/)?)(?:[-;:&=\+\$,\w]+#)?[A-Za-z0-9.-]+|(?:www.|[-;:&=\+\$,\w]+#)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%#.\w_]*)#?(?:[\w]*))?)/ however I would recommend you got to http://blog.mattheworiordan.com/post/13174566389/url-regular-expression-for-links-with-or-without-the to see a complete working example along with an explanation of the regular expression in case you need to extend or tweak it.

The regex you give doesn't work for www. addresses because it is expecting a URI scheme (the bit before the URL, like http://). The 'www.' part in your regular expression doesn't work because it would only match www.:// (which is meaningless)
Try something like this instead:
(((https?|ftp|gopher|telnet|file|notes|ms-help):((//)|(\\\\))+)|(www\.)[\w\d:##%/;$()~_?\+-=\\\.&]*)
This will match something with a valid URI scheme, or something beginning with 'www.'

C# Extracting a name from a string

I want to extract 'James\, Brown' from the string below but I don't always know what the name will be. The comma is causing me some difficuly so what would you suggest to extract James\, Brown?
OU=James\, Brown,OU=Test,DC=Internal,DC=Net
Thanks

A regex is likely your best approach
static string ParseName(string arg) {
var regex = new Regex(#"^OU=([a-zA-Z\\]+\,\s+[a-zA-Z\\]+)\,.*$");
var match = regex.Match(arg);
return match.Groups[1].Value;
}

You can use a regex:
string input = #"OU=James\, Brown,OU=Test,DC=Internal,DC=Net";
Match m = Regex.Match(input, "^OU=(.*?),OU=.*$");
Console.WriteLine(m.Groups[1].Value);

A quite brittle way to do this might be...
string name = #"OU=James\, Brown,OU=Test,DC=Internal,DC=Net";
string[] splitUp = name.Split("=".ToCharArray(),3);
string namePart = splitUp[1].Replace(",OU","");
Console.WriteLine(namePart);
I wouldn't necessarily advocate this method, but I've just come back from a departmental Christmas lyunch and my brain is not fully engaged yet.

I'd start off with a regex to split up the groups:
Regex rx = new Regex(#"(?<!\\),");
String test = "OU=James\\, Brown,OU=Test,DC=Internal,DC=Net";
String[] segments = rx.Split(test);
But from there I would split up the parameters in the array by splitting them up manually, so that you don't have to use a regex that depends on more than the separator character used. Since this looks like an LDAP query, it might not matter if you always look at params[0], but there is a chance that the name might be set as "CN=". You can cover both cases by just reading the query like this:
String name = segments[0].Split('=', 2)[1];

That looks suspiciously like an LDAP or Active Directory distinguished name formatted according to RFC 2253/4514.
Unless you're working with well known names and/or are okay with a fragile hackaround (like the regex solutions) - then you should start by reading the spec.
If you, like me, generally hate implementing code according to RFCs - then hope this guy did a better job following the spec than you would. At least he claims to be 2253 compliant.

If the slash is always there, I would look at potentially using RegEx to do the match, you can use a match group for the last and first names.
^OU=([a-zA-Z])\,\s([a-zA-Z])
That RegEx will match names that include characters only, you will need to refine it a bit for better matching for the non-standard names. Here is a RegEx tester to help you along the way if you go this route.

Replace \, with your own preferred magic string (perhaps & #44;), split on remaining commas or search til the first comma, then replace your magic string with a single comma.
i.e. Something like:
string originalStr = #"OU=James\, Brown,OU=Test,DC=Internal,DC=Net";
string replacedStr = originalStr.Replace("\,", ",");
string name = replacedStr.Substring(0, replacedStr.IndexOf(","));
Console.WriteLine(name.Replace(",", ","));

Assuming you're running in Windows, use PInvoke with DsUnquoteRdnValueW. For code, see my answer to another question: https://stackoverflow.com/a/11091804/628981

If the format is always the same:
string line = GetStringFromWherever();
int start = line.IndexOf("=") + 1;//+1 to get start of name
int end = line.IndexOf("OU=",start) -1; //-1 to remove comma
string name = line.Substring(start, end - start);
Forgive if syntax is not quite right - from memory. Obviously this is not very robust and fails if the format ever changes.