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Remove substring that starts with SOT and ends EOT, from string

I have a program that reads certain strings from memory. The strings contain, for the most part, recognizable characters. At random points in the strings however, "weird" characters appear. Characters I did not recognize. By going to a site that allows me to paste in Unicode characters to see what they are, I found that a selection of the "weird" characters were these:
\x{1} SOH, "start of heading", ctrl-a
\x{2} SOT, "start of text"
\x{3} EOT, "end of text"
\x{7} BEL, bell, ctrl-g
\x{13} dc3, device control three, ctrl-s
\x{11} dc1, device control one, ctrl-q
\x{14} dc4, device control four, ctrl-t
\x{1A} sub, substitute, ctrl-z
\x{6} ack, acknowledge, ctrl-f
I wanted to parse my strings to remove these characters. What I found out though, by looking at the strings, was that all the unwanted characters were always surrounded by the SOT and EOT, respectively.
Therefore, I am thinking that my question is: How can I remove, from a string, all occurrences of substrings that starts with SOT and ends with EOT?
Edit: Attempt at Solution
Using ideas from #RagingCain I made the following method:
private static string RemoveInvalidCharacters(string input)
{
while (true)
{
var start = input.IndexOf('\u0002');
var end = input.IndexOf('\u0003', start);
if (start == -1 || end == -1) break;
Console.WriteLine(#"Start: " + start + #". End: " + end);
var diff = end - start;
input = input.Remove(start, diff);
}
return input;
}
It does the trick, thanks again.

Regex would be your solution and should work fine. You would assign these characters to the Pattern and you can use the sub-method Match or even just Replace them with whitespace " ", or just cut them from the string all together by using "".
Regex.Replace: https://msdn.microsoft.com/en-us/library/xwewhkd1(v=vs.110).aspx
Regex.Match: https://msdn.microsoft.com/en-us/library/bk1x0726(v=vs.110).aspx
Regex example:
public static void Main()
{
string input = "This is text with far too much " +
"whitespace.";
string pattern = "\\s+";
string replacement = " ";
Regex rgx = new Regex(pattern);
string result = rgx.Replace(input, replacement);
Console.WriteLine("Original String: {0}", input);
Console.WriteLine("Replacement String: {0}", result);
}
I know the difficulty though of not being able to "see" them so you should assign them to Char variables by Unicode itself, add them to the pattern for replace.
Char Variables: https://msdn.microsoft.com/en-us/library/x9h8tsay.aspx
Unicode for Start of Text:
http://www.fileformat.info/info/unicode/char/0002/index.htm
Unicode for End of Text:
http://www.fileformat.info/info/unicode/char/0003/index.htm
To apply to your solution:
Does string contain SOT, EOT.
If true, remove entire string/sub-string/SOT or EOT.
It maybe easier to split original string into a string[], then go line by line... it's difficult to parse through your string without knowing what it looks like so hopefully I provided something that helps ^.^

Regular Expression without braces

i have the following sample cases :
1) "Sample"
2) "[10,25]"
I want to form a(only one) regular expression pattern, to which the above examples are passed returns me "Sample" and "10,25".
Note: Input strings do not include Quotes.
I came up with the following expression (?<=\[)(.*?)(?=\]), this satisfies the second case and retreives me only "10,25" but when the first case is matched it returns me blank. I want "Sample" to be returned? can anyone help me.
C#.

here you go, a small regex using a positive lookbehind, sometime these are very handy
Regex
(?<=^|\[)([\w,]+)
Test string
Sample
[10,25]
Result
MATCH 1
[0-6] Sample
MATCH 2
[8-13] 10,25
try at regex101.com
if " is included in your original string, use this regex, this will look for " mark as well, you may choose to remove ^| from lookup if " mark is always included or you may choose to leave it as it is if your text has combination of with and without " marks
Regex
(?<=^|\[|\")([\w,]+)
try at regex101.com

As far as I can tell, the below regex should help:
Regex regex = new Regex(#"^\w+|[[](\w)+\,(\w)+[]]$");
This will match multiple words, or 2 words (alphanumeric) separated by commas and inside square brackets.

One Java example:
// String input = "Sample";
String input = "[10,25]";
String text = "[^,\\[\\]]+";
Pattern pMod = Pattern.compile("(" + text + ")|(?>\\[(" + text + "," + text + ")\\])");
Matcher mMod = pMod.matcher(input);
while (mMod.find()) {
if(mMod.group(1) != null) {
System.out.println(mMod.group(1));
}
if(mMod.group(2)!=null) {
System.out.println(mMod.group(2));
}
}
if input is "[hello&bye,25|35]", then the output is hello&bye,25|35

Regex Replacing only whole matches

I am trying to replace a bunch of strings in files. The strings are stored in a datatable along with the new string value.
string contents = File.ReadAllText(file);
foreach (DataRow dr in FolderRenames.Rows)
{
contents = Regex.Replace(contents, dr["find"].ToString(), dr["replace"].ToString());
File.SetAttributes(file, FileAttributes.Normal);
File.WriteAllText(file, contents);
}
The strings look like this _-uUa, -_uU, _-Ha etc.
The problem that I am having is when for example this string "_uU" will also overwrite "_-uUa" so the replacement would look like "newvaluea"
Is there a way to tell regex to look at the next character after the found string and make sure it is not an alphanumeric character?
I hope it is clear what I am trying to do here.
Here is some sample data:
private function _-0iX(arg1:flash.events.Event):void
{
if (arg1.type == flash.events.Event.RESIZE)
{
if (this._-2GU)
{
this._-yu(this._-2GU);
}
}
return;
}
The next characters could be ;, (, ), dot, comma, space, :, etc.

First of all, you should use Regex.Escape.
You can use then
contents = Regex.Replace(
contents,
Regex.Escape(dr["find"].ToString()) + #"(?![a-zA-Z])",
Regex.Escape(dr["replace"].ToString()));
or even better
contents = Regex.Replace(
contents,
#"\b" + Regex.Escape(dr["find"].ToString()) + #"\b",
Regex.Escape(dr["replace"].ToString()));

I think this is what you're looking for:
contents = Regex.Replace(
contents,
string.Format(#"(?<!\w){0}(?!\w)", Regex.Escape(dr["find"].ToString())),
dr["replace"].ToString().Replace("$", "$$")
);
You can't use \b because your search strings don't always start and end with word characters. Instead, I used (?<!\w) and (?!\w) to make sure the matched substring is not immediately preceded or followed by a word character (i.e., a letter, a digit, or an underscore). I don't know the complete specs for your search strings, so this pattern might need some tweaking.
None of the sample patterns you provided contain regex metacharacters, but like the other responders, I used Regex.Escape() to render it safe anyway. In the replacement string the only character you have to watch out for is the dollar sign (ref), and the way to escape that is with another dollar sign. Notice that I used String.Replace() for that instead of Regex.Replace().

There are two tricks that can help you here:
Order all the search string by length, and replace the longest ones first, that way you won't accidentally replace the shorter ones.
Use a MatchEvaluator and instead of looping through all your rows, search fro all replacement patterns in the string and look them up in your dataset.
Option one is simple, option two would look like this:
Regex.Replace(contents", "_-\\w+", ReplaceIdentifier)
public string ReplaceIdentifier(Match m)
{
DataRow row = FolderRenames.Rows.FindRow("find"); // Requires a primary key on "find"
if (row != null) return row["replace"];
else return m.Value;
}

Regular Expression to get all characters before "-"

How can I get the string before the character "-" using regular expressions?
For example, I have "text-1" and I want to return "text".

So I see many possibilities to achieve this.
string text = "Foobar-test";
Regex Match everything till the first "-"
Match result = Regex.Match(text, #"^.*?(?=-)");
^ match from the start of the string
.*? match any character (.), zero or more times (*) but as less as possible (?)
(?=-) till the next character is a "-" (this is a positive look ahead)
Regex Match anything that is not a "-" from the start of the string
Match result2 = Regex.Match(text, #"^[^-]*");
[^-]* matches any character that is not a "-" zero or more times
Regex Match anything that is not a "-" from the start of the string till a "-"
Match result21 = Regex.Match(text, #"^([^-]*)-");
Will only match if there is a dash in the string, but the result is then found in capture group 1.
Split on "-"
string[] result3 = text.Split('-');
Result is an Array the part before the first "-" is the first item in the Array
Substring till the first "-"
string result4 = text.Substring(0, text.IndexOf("-"));
Get the substring from text from the start till the first occurrence of "-" (text.IndexOf("-"))
You get then all the results (all the same) with this
Console.WriteLine(result);
Console.WriteLine(result2);
Console.WriteLine(result21.Groups[1]);
Console.WriteLine(result3[0]);
Console.WriteLine(result4);
I would prefer the first method.
You need to think also about the behavior, when there is no dash in the string. The fourth method will throw an exception in that case, because text.IndexOf("-") will be -1. Method 1 and 2.1 will return nothing and method 2 and 3 will return the complete string.

Here is my suggestion - it's quite simple as that:
[^-]*

This is something like the regular expression you need:
([^-]*)-
Quick tests in JavaScript:
/([^-]*)-/.exec('text-1')[1] // 'text'
/([^-]*)-/.exec('foo-bar-1')[1] // 'foo'
/([^-]*)-/.exec('-1')[1] // ''
/([^-]*)-/.exec('quux')[1] // explodes

I dont think you need regex to achieve this. I would look at the SubString method along with the indexOf method. If you need more help, add a comment showing what you have attempted and I will offer more help.

You could just use another non-regex based method. Someone gave the suggestion of using Substring, but you could also use Split:
string testString = "my-string";
string[] splitString = testString.Split("-");
string resultingString = splitString[0]; //my
See http://msdn.microsoft.com/en-US/library/ms228388%28v=VS.80%29.aspx for another good example.

If you want use RegEx in .NET,
Regex rx = new Regex(#"^([\w]+)(\-)*");
var match = rx.Match("thisis-thefirst");
var text = match.Groups[1].Value;
Assert.AreEqual("thisis", text);

Find all word and space characters up to and including a -
^[\w ]+-

c# Regex question

I have a problem dealing with the # symbol in Regex, I am trying to remove #sometext
from a text string can't seem to find anywhere where it uses the # as a literal. I have tried myself but doesn't remove the word from the string. Any ideas?
public string removeAtSymbol(string input)
{
Regex findWords = new Regex(______);//Find the words like "#text"
Regex[] removeWords;
string test = input;
MatchCollection all = findWords.Matches(test);
removeWords = new Regex[all.Count];
int index = 0;
string[] values = new string[all.Count];
YesOutputBox.Text = " you got here";
foreach (Match m in all) //List all the words
{
values[index] = m.Value.Trim();
index++;
YesOutputBox.Text = YesOutputBox.Text + " " + m.Value;
}
for (int i = 0; i < removeWords.Length; i++)
{
removeWords[i] = new Regex(" " + values[i]);
// If the words appears more than one time
if (removeWords[i].Matches(test).Count > 1)
{
removeWords[i] = new Regex(" " + values[i] + " ");
test = removeWords[i].Replace(test, " "); //Remove the first word.
}
}
return test;
}

You can remove all occurences of "#sometext" from string test via the method
Regex.Replace(test, "#sometext", "")
or for any word starting with "#" you can use
Regex.Replace(test, "#\\w+", "")
If you need specifically a separate word (i.e. nothing like #comp within tom#comp.com) you may preceed the regex with a special word boundary (\b does not work here):
Regex.Replace(test, "(^|\\W)#\\w+", "")

You can use:
^\s#([A-Za-z0-9_]+)
as the regex to recognize Twitter usernames.

Regex to remove #something from this string: I want to remove #something from this string.
var regex = new Regex("#\\w*");
string result = regex.Replace(stringWithAt, "");
Is that what you are looking for?

I've had good luck applying this pattern:
\B#\w+
This will match any string starting with an # character that contains alphanumeric characters, plus some linking punctuation like the underscore character, if it does not occur on a boundary between alphanumeric and non-alphanumeric characters.
The result of executing this code:
string result = Regex.Replace(
#"#This1 #That2_thing this2#3that #the5Others #alpha#beta#gamma",
#"\B#\w+",
#"redacted");
is the following string:
redacted redacted this2#3that redacted redacted#beta#gamma
If this question is Twitter-specific, then Twitter provides an open source library that helps capture Twitter-specific entities like links, mentions and hashtags. This java file contains the code defining the regular expressions that Twitter uses, and this yml file contains test strings and expected outcomes of many unit tests that exercise the regular expressions in the Twitter library.
Twitter's mention-matching pattern (extracted from their library, modified to remove unnecessary capture groups, and edited to make sense in the context of a replacement) is shown below. The match should be performed in a case-insensitive manner.
(^|[^a-z0-9_])[#\uFF20][a-z0-9_]{1,20}
Here is an example which reproduces the results of the first replacement in my answer:
string result = Regex.Replace(
#"#This1 #That2_thing this2#3that #the5Others #alpha#beta#gamma",
#"(^|[^a-z0-9_])[#\uFF20][a-z0-9_]{1,20}",
#"$1redacted",
RegexOptions.IgnoreCase);
Note the need to include the substitution $1 since the first capture group can't be directly converted into an atomic zero-width assertion.