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Find substring between slashes and replace that part in ASP.NET C#

Using ASP.NET C#, I need to find and replace the word string1 between the last two slashes and replace with string2
Example:
string fullStr = "/this/is/string1/part";
string subStr = "function";
string finalStr = "/this/is/" + subStr + "/part";

And a regex solution:
string fullStr = "this/is/string1/part";
string subStr = "function";
var newstr = Regex.Replace(fullStr, #"/[^/]+/(?=[^/]+$)", m => "/" + subStr + "/");

I don't feel a need of regex here.
string fullStr = "/this/is/string1/part";
string subStr = "function";
string[] fullStrParts = fullStr.Split('/');
fullStrParts[fullStrParts.Length - 2] = subStr;
string finalStr = string.Join("/", fullStrParts);

Remove a substring after a substring

I have a string, for example
"blabla{code}<br />blabla{code}<br />bla{code}<br />"
How to remove all entries of <br /> after {code}?
I've tried this:
public string removeBR(string comment)
{
Regex codeRegex = new Regex("{code}<br />", RegexOptions.Singleline);
return codeRegex.Replace(comment, new MatchEvaluator(m =>
{
string value = m.Groups[0].Value;
return value.Remove(value.Length - 6);
}));
}
It works but is there any easier way?

Hope this helps you
string input = "blabla{code}<br />blabla{code}<br />bla{code}<br />";
string output = input.Replace("{code}<br />", "{code}");
Console.WriteLine(output);
as String.Replace returns a new string in which all occurrences of a specified string in the current instance are replaced with another specified string.

A simple string.Replace should solve this.
string input = #"blabla{code}<br />blabla{code}<br />bla{code}<br />";
string result = input.Replace("{code}<br />", "{code}");

Regex Replaces the text with users case text, how to maintain the actual word case

I am matching and replacing matching words with <span>keyword</span>,
Support users enter the search keyword in lower case as united states it matches the keyword and replaces it
Actual String
String str = "This is United States Of America"
After Match & Replace function string is replaced with lower case match string as entered by the user
This is united states Of America after match
I want to match and replace the string while maintaining the actual case of the matched word or words in the string or database
I use following code for this. How can i alter this so that my requirements are meant
string pattern = #"(\b(?:" + Request["SearchKeyword"].ToString().Trim() + #")\b))";
regex = new Regex(pattern, RegexOptions.IgnoreCase);
result = regex.Replace(result, "<span class='highlight'>" + Request["SearchKeyword"].ToString() + "</span>",);
Desired Output expected
This is United States Of America

You need to use the Match().Value instead of the original request string.
Here is the code you can use:
var req = "united states";
var str = "This is United States Of America";
var pattern = #"((?<=^\p{P}*|\p{Zs})(?:" + req.ToString().Trim() + #")(?=\p{P}*$|\p{Zs}))";
var regx = new Regex(pattern, RegexOptions.IgnoreCase);
var m = regx.Match(str);
var result = string.Empty;
if (m.Success)
result = regx.Replace(str, "<span class='highlight'>" + m.Value + "</span>");
Output:
EDIT: (just in case)
Using a lambda, you can obtain the same result:
var regx = new Regex(pattern, RegexOptions.IgnoreCase);
var result = regx.Replace(str, m => "<span class='highlight'>" + m.Value + "</span>");
It is safe even in case we have no match.

you can use another overload of Regex.Replace method with MatchEvaluator
string str = "This is United States Of America";
string SearchKeyword = "united states";
string pattern = #"(\b(?:" + SearchKeyword.Trim() + #")\b)";
var regex = new Regex(pattern, RegexOptions.IgnoreCase);
var result = regex.Replace(str, new MatchEvaluator(m => "<span class='highlight'>" + m.ToString() + "</span>"));

Regex find all occurrences of a pattern in a string

I have a problem finding all occurences of a pattern in a string.
Check this string :
string msg= "=?windows-1258?B?UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?= =?windows-1258?B?IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=?=";
I want to return the 2 occurrences (in order to later decode them):
=?windows-1258?B?UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?=
and
=?windows-1258?B?IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=?="
With the following regex code, it returns only 1 occurrence: the full string.
var charSetOccurences = new Regex(#"=\?.*\?B\?.*\?=", RegexOptions.IgnoreCase);
var charSetMatches = charSetOccurences.Matches(input);
foreach (Match match in charSetMatches)
{
charSet = match.Groups[0].Value.Replace("=?", "").Replace("?B?", "").Replace("?b?", "");
}
Do you know what I'm missing?

When regexp parser sees the .* character sequence, it matches everything up to the end of the string and goes back, char by char, (greedy match). So, to avoid the problem, you can use a non-greedy match or explicitly define the characters that can appear at a string.
"=\?[a-zA-Z0-9?=-]*\?B\?[a-zA-Z0-9?=-]*\?="

A non-regex way:
string msg= "=?windows-1258?B?UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?= =?windows-1258?B?IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=?=";
string[] charSetOccurences = msg.Split(new string[]{ " " }, StringSplitOptions.None);
foreach (string s in charSetOccurences)
{
string charSet = s.Replace("=?", "").Replace("?B?", "").Replace("?b?", "");
Console.WriteLine(charSet);
}
See an ideone.
And if you still want to use regex, you should make the .* lazy by adding a ?. This was already mentioned by the previous users, but it seems you are not getting matches?
string msg= "=?windows-1258?B?UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?= =?windows-1258?B?IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=?=";
var charSetOccurences = new Regex(#"=\?.*?\?B\?.*?\?=", RegexOptions.IgnoreCase);
var charSetMatches = charSetOccurences.Matches(msg);
foreach (Match match in charSetMatches)
{
string charSet = match.Groups[0].Value.Replace("=?", "").Replace("?B?", "").Replace("?b?", "");
Console.WriteLine(charSet);
}
See another ideone.
The output is the same in both cases:
windows-1258UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?=
windows-1258IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=
EDIT: As per update, see an all in one solution for your problem
string msg= "=?windows-1258?B?UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?= =?windows-1258?B?IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=?=";
var charSetOccurences = new Regex(#"=\?.*?\?[BQ]\?.*?\?=", RegexOptions.IgnoreCase);
MatchCollection matches = charSetOccurences.Matches(msg);
foreach (Match match in matches)
{
string[] encoding = match.Groups[0].Value.Split(new string[]{ "?" }, StringSplitOptions.None);
string charSet = encoding[1];
string encodeType = encoding[2];
string encodedString = encoding[3];
Console.WriteLine("Charset: " + charSet);
Console.WriteLine("Encoding type: " + encodeType);
Console.WriteLine("Encoded String: " + encodedString + "\n");
}
Returns:
Charset: windows-1258
Encoding type: B
Encoded String: UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz
Charset: windows-1258
Encoding type: B
Encoded String: IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=
See this.
Or since we already had the regex, we can use:
string msg= "=?windows-1258?B?UkU6IFRyIDogUGxhbiBkZSBjb250aW51aXTpIGQnYWN0aXZpdOkgZGVz?= =?windows-1258?B?IHNlcnZldXJzIFdlYiBHb1ZveWFnZXN=?=";
var charSetOccurences = new Regex(#"=\?(.*?)\?([BQ])\?(.*?)\?=", RegexOptions.IgnoreCase);
MatchCollection matches = charSetOccurences.Matches(msg);
foreach (Match match in matches)
{
Console.WriteLine("Charset: " + match.Groups[1].Value);
Console.WriteLine("Encoding type: " + match.Groups[2].Value);
Console.WriteLine("Encoded String: " + match.Groups[3].Value + "\n");
}
Returns the same output.

.* is greedy and will match everything from the first ? to the last ?B?.
You need to use either a non-greedy match
=\?.*?\?B\?.*?\?=
or exclude ? from your list of characters
=\?[^?]*\?B\?[^?]*\?=

C# Regexp change link format

On my forum I have a lot of redundant link data like:
[url:30l7ypk7]http://www.box.net/shared/0p28sf6hib[/url:30l7ypk7]
In regexp how can I change these to the format:
http://www.box.net/shared/0p28sf6hib

string orig = "[url:30l7ypk7]http://www.box.net/shared/0p28sf6hib[/url:30l7ypk7]";
string replace = "$1";
string regex = #"\[url:.*?](.*?)\[/url:.*?]";
string fixedLink = Regex.Replace(orig, regex, replace);

This isn't doing it totally in Regex but will still work...
string oldUrl = "[url:30l7ypk7]http://www.box.net/shared/0p28sf6hib[/url:30l7ypk7]";
Regex regExp = new Regex(#"http://[^\[]*");
var match = regExp.Match(oldUrl);
string newUrl = string.Format("<a href='{0}' rel='nofollow'>{0}</a>", match.Value);

This should capture the string \[([^\]]+)\]([^[]+)\[/\1\] and group it so you can pull out the URL like this:
Regex re = new Regex(#"\[([^\]]+)\]([^[]+)\[/\1\]");
var s = #"[url:30l7ypk7]http://www.box.net/shared/0p28sf6hib[/url:30l7ypk7]";
var replaced = s.Replace(s, string.Format("{0}", re.Match(s).Groups[1].Value));
Console.WriteLine(replaced)

This is just from memory but I will try to check it over when I have more time. Should help get you started.
string matchPattern = #"\[(url\:\w)\](.+?)\[/\1\]";
String replacePattern = #"<a href='$2' rel='nofollow'>$2</a>";
String blogText = ...;
blogText = Regex.Replace(matchPattern, blogText, replacePattern);