Develop Reference

C# Regex Help replacing patterns

I'm not really good at regex (I only get to use it a few times a year) and want to see if someone can help with a C# regex statement which finds all instances of
<####-##-##> or </####-##-##>
and replaces it with
<date-####-##-##> or </date-####-##-##>
so that
<2012-01-01>stuff</2012-01-01><2012-05-01>stuff2</2012-05-01>
becomes
<date-2012-01-01>stuff</date-2012-01-01><date-2012-05-01>stuff2</date-2012-05-01>

string test = "<2012-01-01>stuff</2012-01-01><2012-05-01>stuff2</2012-05-01>";
var regex = new Regex(#"<(/?)(\d\d\d\d)-(\d\d)-(\d\d)>");
var result = regex.Replace(test, #"<$1date-$2-$3-$4>");
Console.WriteLine(result);
//output:
//<date-2012-01-01>stuff</date-2012-01-01><date-2012-05-01>stuff2</date-2012-05-01>
Note that the need for detail goes up depending on the other text in the strings your are processing. Are there lots of other tags? Numbers that aren't dates? etc..

If you examine the values inside tags this would be a solution.
if(Regex.IsMatch(input, #"^(19|20)\d\d[- /.](0[1-9]|1[012])[- /.](0[1-9]|[12][0-9]|3[01])$"))
{
input.Replace(input,"date-"+input);
}

How to Extract the Word Following a Symbol?

I have a string that could have any sentence in it but somewhere in that string will be the # symbol, followed by an attached word, sort of like #username you see on some sites.
so maybe the string is "hey how are you" or it's "#john hey how are you".
IF there's an "#" in the string i want to pull what comes immediately after it into its own new string.
in this instance how can i pull "john" into a different string so i could theoretically notify this person of his new message? i'm trying to play with string.contains or .replace but i'm pretty new and having a hard time.
this btw is in c# asp.net

You can use the Substring and IndexOf methods together to achieve this.
I hope this helps.
Thanks,
Damian

Here's how you do it without regex:
string s = "hi there #john how are you";
string getTag(string s)
{
int atSign = s.IndexOf("#");
if (atSign == -1) return "";
// start at #, stop at sentence or phrase end
// I'm assuming this is English, of course
// so we leave in ' and -
int wordEnd = s.IndexOfAny(" .,;:!?", atSign);
if (wordEnd > -1)
return s.Substring(atSign, wordEnd - atSign);
else
return s.Substring(atSign);
}

You should really learn regular expressions. This will work for you:
using System.Text.RegularExpressions;
var res = Regex.Match("hey #john how are you", #"#(\S+)");
if (res.Success)
{
//john
var name = res.Groups[1].Value;
}
Finds the first occurrence. If you want to find all you can use Regex.Matches. \S means anything else than a whitespace. This means it also make hey #john, how are you => john, and #john123 => john123 which may be wrong. Maybe [a-zA-Z] or similar would suit you better (depends on which characters the usernames is made of). If you would give more examples, I could tune it :)
I can recommend this page:
http://www.regular-expressions.info/
and this tool where you can test your statements:
http://regexlib.com/RESilverlight.aspx

The best way to solve this is using Regular Expressions. You can find a great resource here.
Using RegEx, you can search for the pattern you are after. I always have to refer to some documentation to write one...
Here is a pattern to start with - "#(\w+)" - the # will get matched, and then the parentheses will indicate that you want what comes after. The "\w" means you want only word characters to match (a-z or A-Z), and the "+" indicates that there should be one or more word characters in a row.

You can try Regex...
I think will be something like this
string userName = Regex.Match(yourString, "#(.+)\\s").Groups[1].Value;

RegularExpressions. Dont know C#, but the RegEx would be
/(#[\w]+) / - Everything in the parans is captured in a special variable, or attached to RegEx object.

Use this:
var r = new Regex(#"#\w+");
foreach (Match m in r.Matches(stringToSearch))
DoSomething(m.Value);
DoSomething(string foundName) is a function that handles name (found after #).
This will find all #names in stringToSearch

C# Regex Replace

I have a file that is supposed to be \n\n delimited, but of course its not. Some of the lines contains spaces after the \n\n. How do I find a remove all spaces after a \n\n that starts a new line but that is before any other character.
Sample:
\n\nData,Mo re,Data
\n\n Some,Li st,Of
\n\n\nOther,St uff
\n\n\n\n This is another
Desired Output
\n\nData,Mo re,Data
\n\nSome,Li st,Of
\n\nOther,St uff
\n\nThis is another
Regex is probably the answer, but I'm still learning regex. Here's more or less what I've come up with Regex.Replace(input,"^(\n{2,}\s*)", "\n\n") but it doesn't work.
Edit: I should note that I pre-convert from various different line break encodings to \n before this code is needed.

The backslash character needs escaping. Try:
Regex.Replace(input,"^(\n{2,}\\s*)", "\n\n")
Also, you should consider changing \\s* to \\s+ so you don't replace valid line starts unnecesarily.

string test = "\n\nData,Mo re,Data \r\n\n\n Some,Li st,Of \r\n\n\n\nOther,St uff \r\n\n\n\n\n This is another \r\n";
string pattern = "^\n{2,}\\s*";
string result = Regex.Replace(test, pattern, "\n\n", RegexOptions.Multiline);
First, you need the Multiline option. Second, how does your data really look? Notice that where you have a visible cr-lf, I put in \r\n. I did so because you said that it is a \n\n at the beginning of a line that delimits the data. The \n is confusing to work with, so be sure of your data.

Find and Replace RegEx question

I am starting to get a grip on RegEx thanks to all the great help here on SO with my other questions. But I am still suck on this one:
My code is:
StreamReader reader = new StreamReader(fDialog.FileName.ToString());
string content = reader.ReadToEnd();
reader.Close();
I am reading in a text file and I want to search for this text and change it (the X and Y value always follow each other in my text file):
X17.8Y-1.
But this text can also be X16.1Y2.3 (the values will always be different after X and Y)
I want to change it to this
X17.8Y-1.G54
or
X(value)Y(value)G54
My RegEx statement follows but it is not working.
content = Regex.Replace(content, #"(X(?:\d*\.)?\d+)*(Y(?:\d*\.)?\d+)", "$1$2G54");
Can someone please modify it for me so it works and will search for X(wildcard) Y(Wildcard) and replace it with X(value)Y(value)G54?

The regular expression you need is:
X[-\d.]+Y[-\d.]+
Here is how to use it in C#:
string content = "foo X17.8Y-1. bar";
content = Regex.Replace(content, #"X[-\d.]+Y[-\d.]+", "$0G54");
Console.WriteLine(content);
Output:
foo X17.8Y-1.G54 bar

What comes after "X(value)Y(value)" in your text file? A space? A newline? Another "X(value)Y(value)" value pair?
I'm not very good using shortcuts in regexes, like \d, nor am I familiar with .NET, but I had used the following regex to match the value pair:
(X[0-9.-]+Y[0-9.-]+)
And the replacement is
$1G54
This will work as long as a value pair is not directly followed by a digit, period or a dash.

To be picky about the input, you could use
string num = #"-?(?:\d+\.\d+|\d+\.|\.\d+|\d+)";
content = Regex.Replace(content, "(?<x>X" + num + ")(?<y>Y" + num + ")", "${x}${y}G54");
Is there a reliable terminator for the Y value? Say it's whitespace:
content = Regex.Replace(content, #"(X.+?)(Y.+?)(\s)", "$1$2G54$3");
How robust does the code need to be? If it's rewriting debugging output or some other quick-and-dirty task, keep it simple.

I know this doesn't answer your question directly, but you should check out Expresso. It's a .NET Regular Expression Tool that allows you to debug, test, and fine-tune your complex expressions. It's a life-saver.
More of a do-it yourself answer, but it'll be helpful even if someone gives you an answer here.

It looks like you just need to support optional negative values:
content = Regex.Replace(content, #"(X-?(?:\d*\.)?\d+)*(Y-?(?:\d*\.)?\d+)", "$1$2G54");

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.