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Regex in between characters

Im trying to create a regex that will match ascii characters in a string so that they be converted with hex afterwards. The string is received as follows:<<<441234567895,ASCII,4,54657379>>> so I am looking to match everything between the third comma and the >>> characters at the end of the string like so.
<<<441234567895,ASCII,4,54657379>>>
So far I have managed to create this regex (/([^,]*,[^,]*)*([^;]*)>>>/) for it but the third comma is picked up as well which I don't want. What do I need to do to remove it from the match?
thanks Callum

(?<=,)[^,]+(?=>>>)
This should do it.See demo.
https://regex101.com/r/sJ9gM7/79

Do you need to use Regex?
string input = "<<<441234567895,ASCII,4,54657379>>>";
string match = input.Substring(3, input.Length - 6).Split(',')[3];
You can also use further splits on the beginning and ending padding strings or check their lengths if you want something safer than the Substring magic.

Removing Sub-string with some pattern from a string

I have a string something like JSON format:
XYZ DIV Parameters: width=\"1280\" height=\"720\", session=\"1\"
Now I want to remove width=\"1280\" height=\"720\" from this string.
Note: There can be any number in place of 1280 and 720. So, I can't just replace it with null.
Please tell me how to solve it? Either by Regex or any other better method possible.

Regex to be replaced with empty string:
(width|height)=\\"\d+\\"
Regex visualization:
Code:
string input = #"XYZ DIV Parameters: width=\""1280\"" height=\""720\"", session=\""1\""";
string output = Regex.Replace(input, #"(width|height)=\\""\d+\\""", string.Empty);

You could do a find and replace using the following regex:
width=\\"\d*+\\" replace with a blank string, as well as replacing height=\\"\d*+\\" with a blank string.
This is removing the entire text of width=\"XYZ\", if you wanted to just replace the numbers or blank out the numbers you can replace with a string that suits your needs (width=\"\" for example)
If you can guarantee the width and height will ALWAYS be in that format and ALWAYS follow each other seperated by a space, you can combine that into one bigger regex find/replace using width=\\"\d*+\\" height=\\"\d*+\\".
A little more explanation on the regex so you take something away, not just a quick fix :)
width=\\"\d*+\\" breaks down to:
width= pretty simple, just find the text you are looking for to start your removal.
\\" since \ is a special char in regex you have to escape it, then the " char can just follow it up like normal.
\d*+ digits \d, zero or more of them *, and then non greedy +. The important part here is the non greedy on the digits. If you left that off, your regex would look and consume digits until it found the last ". Not 100% needed in your case (since height is buffering) but it is still a lot safer.
\\" to end the regex out

This will do it:
string resultString = null;
try {
Regex regexObj = new Regex(#"^(.*?)width=\\"".*?\\"" height=\\"".*?\\""(.*?)$", RegexOptions.IgnoreCase);
resultString = regexObj.Replace(subjectString, #"$1width=\""\"" height=\""\""$2");
} catch (ArgumentException ex) {
// Syntax error in the regular expression
}

Regex to exclude all chars except letters

I'm a real regex n00b so I ask your help:
I need a regex witch match only letters and numbers and exclude punctations, non ascii characters and spaces.
"ilikestackoverflow2012" would be a valid string.
"f### you °§è" not valid.
"hello world" not valid
"hello-world" and "*hello_world*" not valid
and so on.
I need it to make a possibly complex business name url friendly.
Thanks in advance!

You don't need regex for this.
string s = "......"
var isValid = s.All(Char.IsLetterOrDigit);
-
I need it to make a possibly complex business name url friendly
You can also use HttpUtility.UrlEncode
var urlFriendlyString = HttpUtility.UrlEncode(yourString);

To validate a string you can use the following regular expression with Regex.IsMatch:
"^[0-9A-Za-z]+$"
Explanation:
^ is a start of string anchor.
[...] is a character class.
+ means one or more.
$ is an end of string anchor.
I need it to make a possibly complex business name url friendly
Then you want to replace the characters that don't match. Use Regex.Replace with the following regular expression:
"[^0-9A-Za-z]+"
Explanation:
[^...] is a negated character class.
Code:
string result = Regex.Replace(input, "[^0-9A-Za-z]+" , "");
See it working online: ideone
Note that different business names could give the same resulting string. For example, businesses whose names contain only Chinese characters will all give the empty string.

You can use below regex.
^[a-zA-Z0-9]+$

^[0-9a-zA-Z]+$
Matches one or more alphanumeric characters with no spaces or non-alpha characters.

Try this:
var regex = new Regex(#"^[a-zA-Z0-9]+$");
var test = new[] {"ilikestack", "hello world", "hello-world", "###"};
foreach (var s in test)
Console.WriteLine("{0}: {1}", s, regex.IsMatch(s));
EDIT: If you want something like #Andre_Miller said, you should use the same regex with Regex.Replace();
Regex.Replace(s, #"[^a-zA-Z0-9]+", "")
OR
var regex = new Regex(#"^[a-zA-Z0-9]+$");
regex.Replace("input-string-##$##");

Try
^[a-zA-Z0-9]+$
www.regexr.com is a GREAT resource.

What's wrong with [:alnum:]? It's a posix standard. So your whole regex would be: ^[:alnum:]+$.
The wikipedia article for regular expressions includes lots of examples and details.

Regular expression to check for special characters except space

I want to check for special characters in a string EXCEPT spaces and delete them.
Ex: input = "Oh Boy!!#$" output = "Oh Boy"
Can someone help me with the regular expression to implement this in C#

This is one way:
Console.WriteLine(Regex.Replace("Oh Boy!!#$", #"[^\w ]", ""));

Replacing numbers in strings with C#

I'd thought i do a regex replace
Regex r = new Regex("[0-9]");
return r.Replace(sz, "#");
on a file named aa514a3a.4s5 . It works exactly as i expect. It replaces all the numbers including the numbers in the ext. How do i make it NOT replace the numbers in the ext. I tried numerous regex strings but i am beginning to think that its a all or nothing pattern so i cant do this? do i need to separate the ext from the string or can i use regex?

This one does it for me:
(?<!\.[0-9a-z]*)[0-9]
This does a negative lookbehind (the string must not occur before the matched string) on a period, followed by zero or more alphanumeric characters. This ensures only numbers are matched that are not in your extension.
Obviously, the [0-9a-z] must be replaced by which characters you expect in your extension.

I don't think you can do that with a single regular expression.
Probably best to split the original string into base and extension; do the replace on the base; then join them back up.

Yes, I thing you'd be better off separating the extension.
If you are sure there is always a 3-character extension at the end of your string, the easiest, most readable/maintainable solution would be to only perform the replace on
yourString.Substring(0,YourString.Length-4)
..and then append
yourString.Substring(YourString.Length-4, 4)

Why not run the regex on the substring?
String filename = "aa514a3a.4s5";
String nameonly = filename.Substring(0,filename.Length-4);