Regular expression match substring - c#

I tried to create a regular expression which pulls everything that matches:
[aA-zZ]{2}[0-9]{5}
The problem is that I want to exclude from matching when I have eg. ABCD12345678
Can anyone help me resolve this?
EDIT1:
I am looking two letters and five digits in the string, but I want to exclude from matching when I have string like ABCD12345678, because when I use above regular expression it will return CD12345.
EDIT2:
I didn't check everything but I think I found answer:
WHEN field is null then field
WHEN fnRegExMatch(field, '[a-zA-Z]{2}[0-9]{5}') = 'N/A' THEN field
WHEN field like '%[^a-z][a-z][a-z][0-9][0-9][0-9][0-9][0-9][^0-9]%' or field like '[a-z][a-z][0-9][0-9][0-9][0-9][0-9][^0-9]%' THEN fnRegExMatch(field, '[a-zA-Z]{2}[0-9]{5}')
ELSE field

First [aA-zZ] haven't any sense, second use word boundaries:
\b[a-zA-Z]{2}[0-9]{5}\b
You could also use case insensitive modifier:
(?i)\b[a-z]{2}[0-9]{5}\b
According to your comment, it seems you may have underscore after the five digits. In this case, word boundary doesn't work, you have to use ths instead:
(?i)(?<![a-z])([a-z]{2}[0-9]{5})(?![0-9])
(?<![a-z]) is a negative lookbehind that assumes you haven't a letter before the two that are mandatory
(?![0-9]) is a negative lookahead that assumes you haven't a digit after the five that are mandatory

This would be the code, along with usage samples.
public static Regex regex = new Regex(
"\\b[a-zA-Z]{2}\\d{5}\\b",
RegexOptions.CultureInvariant
| RegexOptions.Compiled
);
//// Replace the matched text in the InputText using the replacement pattern
// string result = regex.Replace(InputText,regexReplace);
//// Split the InputText wherever the regex matches
// string[] results = regex.Split(InputText);
//// Capture the first Match, if any, in the InputText
// Match m = regex.Match(InputText);
//// Capture all Matches in the InputText
// MatchCollection ms = regex.Matches(InputText);
//// Test to see if there is a match in the InputText
// bool IsMatch = regex.IsMatch(InputText);
//// Get the names of all the named and numbered capture groups
// string[] GroupNames = regex.GetGroupNames();
//// Get the numbers of all the named and numbered capture groups
// int[] GroupNumbers = regex.GetGroupNumbers();

Related

Using a regex with 'or' operator and getting matched groups?

I have some string in a file in the format
rid="deqn1-2"
rid="deqn3"
rid="deqn4-5a"
rid="deqn5b-7"
rid="deqn7-8"
rid="deqn9a-10v"
rid="deqn11a-12c"
I want a regex to match each deqnX-Y where X and Y are either both integers or both combination of integer and alphabet and if there is a match store X and Y in some variables.
I tried using the regex (^(\d+)-(\d+)$|^(\d+[a-z])-(\d+[a-z]))$
, but how do I get the values of the matched groups in variables?
For a match between two integers the groups would be (I think)
Groups[2].Value
Groups[3].Value
and for match between two integer and alphabet combo will be
Groups[4].Value
Groups[5].Value
How do I determine which match actually occured and then capture the matching groups accordingly?
As branch reset(?|) is not supported in C#, we can use named capturing group with same name like
deqn(?:(?<match1>\d+)-(?<match2>\d+)|(?<match1>\d+\w+)-(?<match2>\d+\w+))\b
regextester demo
C# code
String sample = "deqn1-2";
Regex regex = new Regex("deqn(?:(?<match1>\\d+)-(?<match2>\\d+)|(?<match1>\\d+\\w+)-(?<match2>\\d+\\w+))\\b");
Match match = regex.Match(sample);
if (match.Success) {
Console.WriteLine(match.Groups["match1"].Value);
Console.WriteLine(match.Groups["match2"].Value);
}
dotnetfiddle demo
You could simply not care. One of the pairs will be empty anyway. So what if you just interpret the result as a combination of both? Just slap them together. First value of the first pair plus first value of the second pair, and second value of the first pair plus second value of the second pair. This always gives the right result.
Regex regex = new Regex("^deqn(?:(\\d+)-(\\d+)|(\\d+[a-z])-(\\d+[a-z]))$");
foreach (String str in listData)
{
Match match = regex.Match(str);
if (!match.Success)
continue;
String value1 = Groups[1].Value + Groups[3].Value;
String value2 = Groups[2].Value + Groups[4].Value;
// process your strings
// ...
}

Find String Between To Identical Control Separators?

I'm reading from a file, and need to find a string that is encapsulated by two identical non-ascii values/control seperators, in this case 'RS'
How would I go about doing this? Would I need some form of regex?
RS stands for Record Separator, and it has a value of 30 (or 0x1E in hexadecimal). You can use this regular expression:
\x1E([\w\s]*?)\x1E
That matches the RS, then matches any letter, number or space, and then again the RS. The ? is to make the regex match as less characters as possible, in case there are more RS characters afterwards.
If you prefer not to match numbers, you could use [a-zA-Z\s] instead of [\w\s].
Example:
string fileContents = "Something \u001Eyour string\u001E more things \u001Eanother text\u001E end.";
MatchCollection matches = Regex.Matches(fileContents, #"\x1E([\w\s]*?)\x1E");
if (matches.Count == 0)
return; // Not found, display an error message and exit.
foreach (Match match in matches)
{
if (match.Groups.Count > 1)
Console.WriteLine(match.Groups[1].Value);
}
As you can see, you get a collection of Match, and each match.Value will have the whole matched string including the separators. match.Groups will have all matched groups, being the first one again the whole matched string (that's by default) and then each of your groups (those between parenthesis). In this case, you only have one in your regex, so you just need the second one on that list.
Using regex you can do something like this:
string pattern = string.Format("{0}(.*){1}",firstString,secondString);
var matches = Regex.Matches(myString, pattern);
foreach (Match match in matches)
{
foreach (Capture capture in match.Captures)
{
//Do stuff, with the current you should remove firstString and secondString from the capture.Value
}
}
After that use Regex.match to find the string that match with the pattern built before.
Remember to escape all the special char for regex.
You can use Regex.Matches, I'm using X as the separator in this example:
var fileContents = "Xsomething1X Xsomething2X Xsomething3X";
var results = Regex.Matches(fileContents, #"(X).*?(\1)");
The you can loop on results to do anything you want with the matches.
The \1 in the regex means "reference first group". I've put X between () so it is going to be group 1, the I use \1 to say that the match in this place should be exactly the same as the group 1.
You don't need a regular expression for that.
Read the contents of the file (File.ReadAllText).
Split on the separator character (String.Split).
If you know there's only one occurrence of your string, take the second array element (result[1]). Otherwise, take every other entry (result.Where((x, i) => i % 2 == 1)).

Regex to text before set of numbers

I have text like this
Inc12345_Month
Ted12345_Month
J8T12345_Month
What I need to do is extract the 12345 and also remove everything before it. This will be done in C#
.+?(?=\d_Monthly) was working in a regex tester online but when I put it in my code it only returned 5_Month.
Edit: the 12345 could be a variable length so I cannot [0-9] multiple times.
Edit2: Code this was just to try and remove everything before the 12345
string text = /* the above text pulled in from a file */;
Regex reg = new Regex(#".+?(?=\d+_Monthly)");
text = reg.Replace(string, "");
You can use this function to strip it:
private static Regex getNumberAndBeyondRegex = new Regex(^.{2}\D+(\d.*)$", RegexOptions.Compiled);
public static string GetNumberAndBeyond(string input)
{
var match = getNumberAndBeyondRegex.Match(input);
if (!match.Success) throw new ArgumentException("String isn't in the correct format.", "input");
return match.Groups[1].Value;
}
The regex at work is ^.{2}\D+(\d.*)$
It works by grabbing anything that's a number, after at least one character that isn't a number. It'll not only match _Month but also other endings.
The regex exists out of a few parts:
^ matches the beginning of the string
.{2} matches any two characters, to prevent a digit from matching if it's the first or 2nd character, you can increase this number to be equal to the minimum prefix length - 1
\D+ matches at least one character that isn't a number
( starts capturing a group
\d.* matches at least one number and any values beyond that
) closes the capturing group
$ matches the end of the string
There are a lot of different regex flavors, many of them have slight differences in terms of escaping, capturing, replacing and quite surely some others.
For testing .NET regexes online I use the free version of the tool RegexHero, it has an popup every now and then, but it makes up for that time by showing you live results, capture groups, and instant replacing. Next to having quite a lot of features.
If you want to match anywhere within the string, you can use the regex \d+_Month, it is very similiar to your original regex. In code:
new Regex("\d+_Month").Match(input).Value
Edit:
Based on the format you supplied in the comment I've created a regex and function to parse the entire file name:
private static Regex parseFileNameRegex = new Regex(#"^.*\D(\d+)_Month_([a-zA-Z]+)\.(\w+)$", RegexOptions.Compiled);
public static bool TryParseFileName(string fileName, out int id, out string month, out string fileExtension)
{
id = 0; month = null; fileExtension = null;
if (fileName == null) return false;
var match = parseFileNameRegex.Match(fileName);
if (!match.Success) return false;
if (!int.TryParse(match.Groups[1].Value, out id) || id < 1) return false; // Convert the ID into a number
month = match.Groups[2].Value;
fileExtension = match.Groups[3].Value;
return true;
}
In the parse function it requires the ID to be at least 1, 0 isn't accepted (and negative numbers won't match the regex), if you don't want this restriction, simply remove || id < 1 from the function.
Using the function would look like:
int id; string month, fileExtension;
if (!TryParseFileName("CompanyName_ClientName12345_Month_Nov.pdf", out id, out month, out fileExtension))
throw new FormatException("File name is incorrectly formatted."); // Do whatever you want when you get an invalid filename
// Use id, month and fileExtension here :)
The regex ^.*\D(\d+)_Month_([a-zA-Z]+)\.(\w+)$ works like:
^ matches the beginning of the string
.*\D matches at least one non-numeric character
(\d+) captures at least 1 number, this is the ID
_Month_ is the literal text in between
([a-zA-Z]+) matches and captures at least 1 letter, this is the month
\. matches a . character
(\w+) matches and captures any alphanumeric (letters and numbers), this is the file extension
$ matches the end of the string
Using :
Regex reg = new Regex(#"\D+(?=(\d+)_Monthly)");
is more explicit, the result is in Groups[1].
Part by part:
.+?
Match anything, maybe. This doesn't make any sense to me. It would be equivalent to ".*", which may or may not be what you meant.
(?=
start a group
\d
Match exactly 1 decimal, which explains what you are seeing, and the rest of the number is matched by .+? which is outside the group
_Monthly
match the literal text
)
end group
I think what you want is:
.*(?=\d+_Monthly)
I guess you are missing the + sign after \d
.+?(?=\d+_Monthly)
This should ask for one or more digits.
If you don't need anything before the number, this should work:
(\d+_Month)
I use Derek Slager's regex tester when I'm working with C# regex.
Better dotnet regular expression tester

Replace all characters and first 0's (zeroes)

I am trying to replace all characters inside a Regular Expression expect the number, but the number should not start with 0
How can I achieve this using Regular Expression?
I have tried multiple things like #"^([1-9]+)(0+)(\d*)"and "(?<=[1-9])0+", but those does not work
Some examples of the text could be hej:\\\\0.0.0.22, hej:22, hej:\\\\?022 and hej:\\\\?22, and the result should in all places be 22
Rather than replace, try and match against [1-9][0-9]*$ on your string. Grab the matched text.
Note that as .NET regexes match Unicode number characters if you use \d, here the regex restricts what is matched to a simple character class instead.
(note: regex assumes matches at end of line only)
According to one of your comments hej:\\\\0.011.0.022 should yield 110022. First select the relevant string part from the first non zero digit up to the last number not being zero:
([1-9].*[1-9]\d*)|[1-9]
[1-9] is the first non zero digit
.* are any number of any characters
[1-9]\d* are numbers, starting at the first non-zero digit
|[1-9] includes cases consisting of only one single non zero digit
Then remove all non digits (\D)
Match match = Regex.Match(input, #"([1-9].*[1-9]\d*)|[1-9]");
if (match.Success) {
result = Regex.Replace(match.Value, "\D", "");
} else {
result = "";
}
Use following
[1-9][0-9]*$
You don't need to do any recursion, just match that.
Here is something that you can try The87Boy you can play around with or add to the pattern as you like.
string strTargetString = #"hej:\\\\*?0222\";
string pattern = "[\\\\hej:0.?*]";
string replacement = " ";
Regex regEx = new Regex(pattern);
string newRegStr = Regex.Replace(regEx.Replace(strTargetString, replacement), #"\s+", " ");
Result from the about Example = 22

C# Regular Expressions

I have a string that has multiple regular expression groups, and some parts of the string that aren't in the groups. I need to replace a character, in this case ^ only within the groups, but not in the parts of the string that aren't in a regex group.
Here's the input string:
STARTDONTREPLACEME^ENDDONTREPLACEME~STARTREPLACEME^ENDREPLACEME~STARTREPLACEME^BLAH^ENDREPLACEME~STARTDONTREPLACEME^BLAH^ENDDONTREPLACEME~
Here's what the output string should look like:
STARTDONTREPLACEME^ENDDONTREPLACEME~STARTREPLACEMEENDREPLACEME~STARTREPLACEMEBLAHENDREPLACEME~STARTDONTREPLACEME^BLAH^ENDDONTREPLACEME~
I need to do it using C# and can use regular expressions.
I can match the string into groups of those that should and shouldn't be replaced, but am struggling on how to return the final output string.
I'm not sure I get exactly what you're having trouble with, but it didn't take long to come up with this result:
string strRegex = #"STARTREPLACEME(.+)ENDREPLACEME";
RegexOptions myRegexOptions = RegexOptions.None;
Regex myRegex = new Regex(strRegex, myRegexOptions);
string strTargetString = #"STARTDONTREPLACEME^ENDDONTREPLACEME~STARTREPLACEME^ENDREPLACEME~STARTREPLACEME^BLAH^ENDREPLACEME~STARTDONTREPLACEME^BLAH^ENDDONTREPLACEME~";
string strReplace = "STARTREPLACEMEENDREPLACEME";
return myRegex.Replace(strTargetString, strReplace);
By using my favorite online Regex tool: http://regexhero.net/tester/
Is that helpful?
Regex rgx = new Regex(
#"\^(?=(?>(?:(?!(?:START|END)(?:DONT)?REPLACEME).)*)ENDREPLACEME)");
string s1 = rgx.Replace(s0, String.Empty);
Explanation: Each time a ^ is found, the lookahead scans ahead for an ending delimiter (ENDREPLACEME). If it finds one without seeing any of the other delimiters first, the match must have occurred inside a REPLACEME group. If the lookahead reports failure, it indicates that the ^ was found either between groups or within a DONTREPLACEME group.
Because lookaheads are zero-width assertions, only the ^ will actually be consumed in the event of a successful match.
Be aware that this will only work if delimiters are always properly balanced and groups are never nested within other groups.
If you are able to separate into groups that should be replaced and those that shouldn't, then instead of providing a single replacement string, you should be able to use a MatchEvaluator (a delegate that takes a Match and returns a string) to make the decision of which case it is currently dealing with and return the replacement string for that group alone.
You may also use an additional regex inside the MatchEvaluator. This solution produces the expected output:
Regex outer = new Regex(#"STARTREPLACEME.+ENDREPLACEME", RegexOptions.Compiled);
Regex inner = new Regex(#"\^", RegexOptions.Compiled);
string replaced = outer.Replace(start, m =>
{
return inner.Replace(m.Value, String.Empty);
});

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