I have the following string:
21>Please be specific. What do you mean by that?21>Hello are you there623>Simon?
I want to split it into:
21>Please be specific. What do you mean by that?
21>Hello are you there
623>Simon?
Basically the splitter is the numeric value (21 and 623 in this case) followed by the >.
My implementation is that I find the > char, then walk back until I find a non-numeric value.
So basically using sub-string and the like. But it's ugly and I am certain there is a better Regex implementation, but I don't know enough about it.
So can Regex be used here?
You can achieve that with look ahead and look behind, so that your match is the zero length area between what you want to split.
string s = "21>Please be specific. What do you mean by that?21>Hello are you there623>Simon?";
Regex reg = new Regex(#"(?<=\D)(?=\d+>)");
var r = reg.Split(s);
foreach(var i in r)
Console.WriteLine(i);
Will output
21>Please be specific. What do you mean by that?
21>Hello are you there
623>Simon?
Try with following regex. It matches the zero width between something and number>
Regex: (?<=\D)(?=\d+>) replaced with \n for demo.
Explanation:
(?<=\D) looks behind to see if it's not a number.
(?=\d+>) looks ahead to see if it's a number>.
And matched the zer0-width between them.
Regex101 Demo
Try: [0-9]+>
Explanation:
[0-9]+ At least 1 digit
> followed by >
It might make sense to replace the matches with \n$0, which will move them to individual lines.
Related
I want to chunk a credit card number (in my case I always have 16 digits) into 4 chunks of 4 digits.
I've succeeded doing it via positive look ahead :
var s="4581458245834584";
var t=Regex.Split(s,"(?=(?:....)*$)");
Console.WriteLine(t);
But I don't understand why the result is with two padded empty cells:
I already know that I can use "Remove Empty Entries" flag , But I'm not after that.
However - If I change the regex to (?=(?:....)+$) , then I get this result :
Question
Why does the regex emit empty cells ? and how can I fix my regex so it produce 4 chunks at first place ( without having to 'trim' those empty entries )
But I don't understand why the result is with two padded empty cells:
Let's try breaking down your regex.
Regex: (?=(?:....)*$)
Explanation: Lookahead (?=) for anything 4 times(?:....) for zero or more times. Just looking ahead and matching nothing will match zero width.
Since you are using * quantifier which says zero or more it matches first zero width at beginning or string and also at end of string.
Visualize it from this snapshot of Regex101 Demo
[
So How can I select only those 3 splitters in the middle ?
I don't know C# very well but this 3 step method might work for you.
Search with (\d{4}) and replace with -\1. Result will be -4581-4582-4583-4584. Demo
Now replace first - by searching with ^-. Result will be 4581-4582-4583-4584. Demo
At last search for - and split on it. Demo. Used \n to substitute for demo purpose.
Alternative Solution Inspired from Royi's answer.
Regex: (?=(?!^)(?:\d{4})+$)
Explanation:
(?= // Look ahead for
(?!^) // Not the start of string
(?:\d{4})+$ // Multiple group of 4 digits till end of string
)
Since nothing is matched and only lookaround assertions are used, it will pinpoint Zero width after a group of 4 digits.
Regex101 Demo
It seems like I've found an answer.
Looking at those splitters - I needed to get rid of the edges :
So I thought - how can I tell the regex engine "not at the start of the line " ?
Which is exactly what (?!^) does
So here is the new regex :
var s="4581458245834584";
var t=Regex.Split(s,"(?!^)(?=(?:....)+$)");
Console.WriteLine(t);
Result :
Umm, I don't know WHY you need Regex for this. You just overcomplicate things. Better way is to just split it manually:
var values = new List<int>();
for(int i =0;i < 4;i++)
{
var value = int.Parse(s.Substring(i*4, 4));
values.Add(value);
}
Regex solution:
var s = "4581458245834584";
var separated = Regex.Match(s, "(.{4}){4}").Groups[1].Captures.Cast<Capture>().Select(x => x.Value).ToArray();
It has been mentioned already that the * quantifier also matches at the end of string where there are zero group-matches ahead. To avoid matching at start and end you can use \B non word boundary which only matches between two word characters not giving matches for start and end.
\B(?=(?:.{4})+$)
See demo at regex101
Because the lookahead won't be triggered at start or end of the string you could even use *
I have the following string:
"121 fd412 4151 3213, 421, 423 41241 fdsfsd"
And I need to get 3213 and 421 - because they both have space in front of them, and a coma behind.
The result will be set inside the string array...How can I do that?
"\\d+" catches every integer.
"\s\\d+(,)" throws some memory errors.
EDIT.
space to the left (<-) of the number, coma to the right (->)
EDIT 2.
string mainString = "Tests run: 5816, 8346, 28364 iansufbiausbfbabsbo3 4";
MatchCollection c = Regex.Matches(a, #"\d+(?=\,)");
var myList = new List<String>();
foreach(Match match in c)
{
myList.Add(match.Value);
}
Console.Write(myList[1]);
Console.ReadKey();
Your regex syntax is incorrect for wanting to match both digits, if you want them as separate results, you could do:
#"\s(\d+),\s(\d+)\s"
Live Demo
Edit
#"\s(\d+),"
Live Demo
\s\\d+(,):
\s is not properly escaped, should be \\s, same as for \\d
\\d matches single digit, you need \\d+ - one or more consecutive digits
(,) captures comma, do you really need this? seems like you need to capture a number, so \\s(\\d+),
you said "because they both have space behind them, and a coma in front", so probably ,\\s(\\d+)
How about this expression :
" \d+," // expression without the quotes
it should find what you need.
How to work with regular expression can you check on the MSDN
Hope it helps
Another solution
\s(\d+), // or maybe you'll need a double slash \\
Output:
3213
421
Demo
I think you mean you're looking for something like ,<space><digit> not ,<digit><space>
If so, try this:
, (\d+) //you might need to add another backslash as the others have noted
Well, based on your new edit
\s(\d+),
Test it here
It's all you need, only the numbers
\d+(?=\,)
I have code that searches a folder that contains SQL patch files. I want to add file names to an array if they match the following name format:
number-text-text.sql
What Regex would I use to match number-text-text.sql?
Would it be possible to make the Regex match file names where the number part of the file name is between two numbers? If so what would be the Regex syntax for this?
The following regex make it halfway there:
\d+-[a-zA-Z]+-[a-zA-Z]+\.sql
Regarding to match in a specific range it gets trickier as regex doesn't have a simple way to handle ranges. To limit the match to a filename with a number between 2 and 13 this is the regex:
([2-9]|1[0-3])-[a-zA-Z]+-[a-zA-Z]+\.sql
Your regular expression should be:
(\d+)-[a-zA-Z]+-[a-zA-Z]+\.sql
You would then use the first captured group to check if your number is between the two numbers you desire. Don't try to check if a number is within a range with a regular expression; do it in two steps. Your code will be much clearer for it.
How about:
\d+-[^-]+-[^-]+\.sql
Edit: You want just letters, so here it is without specific ranges.
\d+-[a-z]+-[a-z]+\.sql - You'll also want to use the i flag, not sure how that's done in c#, but here it is in js/perl:
/\d+-[a-z]+-[a-z]+\.sql/i
Ranges are more difficult. Here's an example of how to match 0-255:
([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])
So to match (0-255)-text-text.sql, you'd have this:
/^(?:[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])-[a-z]+-[a-z]+\.sql/i
(I put the digits in a non-capturing group and matched from the beginning of the string to prevent partial matches on the number and in case you're expecting numbered groups or something).
Basically every time you need another digit of possibility, you'll need to add a new condition inside this case. The smaller the digit you'd like to match, the more cases you'll need as well. What is your desired min/max? AFAIK there's not a simple way to do this dynamically (although I'd love for someone to show me I'm wrong about that).
The simplest way to get around this would be to simply capture the digits, and use native syntax to see if it's in your range. Example in js:
var match = filename.match(/(\d+)-[a-z]+-[a-z]+\.sql/i);
if(match && match[1] < maximumNumber && match[1] > minimumNumber){
doStuff();
}
This should work:
select '4-dfsg-asdfg.sql' ~ E'^[0-9]+-[a-zA-Z]+-[a-zA-Z]+\\.sql$'
This restricts the TEXT to simple ASCII characters. May or may not be what you want.
This is tested in PostgreSQL. Regular expression flavors differ a lot between implementations. You probably know that?
Anchors at begin ^ and end $ are optional, depending how you are going to do it.
This has probably been answered somewhere before but since there are millions of unrelated posts about string formatting.
Take the following string:
24:Something(true;false;true)[0,1,0]
I want to be able to do two things in this case. I need to check whether or not all the following conditions are true:
There is only one : Achieved using Split() which I needed to use anyway to separate the two parts.
The integer before the : is a 1-3 digit int Simple int.parse logic
The () exists, and that the "Something", in this case any string less than 10 characters, is there
The [] exists and has at least 1 integer in it. Also, make sure the elements in the [] are integers separated by ,
How can I best do this?
EDIT: I have crossed out what I've achieved so far.
A regular expression is the quickest way. Depending on the complexity it may also be the most computationally expensive.
This seems to do what you need (I'm not that good so there might be better ways to do this):
^\d{1,3}:\w{1,9}\((true|false)(;true|;false)*\)\[\d(,[\d])*\]$
Explanation
\d{1,3}
1 to 3 digits
:
followed by a colon
\w{1,9}
followed by a 1-9 character alpha-numeric string,
\((true|false)(;true|;false)*\)
followed by parenthesis containing "true" or "false" followed by any number of ";true" or ";false",
\[\d(,[\d])*\]
followed by another set of parenthesis containing a digit, followed by any number of comma+digit.
The ^ and $ at the beginning and end of the string indicate the start and end of the string which is important since we're trying to verify the entire string matches the format.
Code Sample
var input = "24:Something(true;false;true)[0,1,0]";
var regex = new System.Text.RegularExpressions.Regex(#"^\d{1,3}:.{1,9}\(.*\)\[\d(,[\d])*\]$");
bool isFormattedCorrectly = regex.IsMatch(input);
Credit # Ian Nelson
This is one of those cases where your only sensible option is to use a Regular Expression.
My hasty attempt is something like:
var input = "24:Something(true;false;true)[0,1,0]";
var regex = new System.Text.RegularExpressions.Regex(#"^\d{1,3}:.{1,9}\(.*\)\[\d(,[\d])*\]$");
System.Diagnostics.Debug.Assert(regex.IsMatch(input));
This online RegEx tester should help refine the expression.
I think, the best way is to use regular expressions like this:
string s = "24:Something(true;false;true)[0,1,0]";
Regex pattern = new Regex(#"^\d{1,3}:[a-zA-z]{1,10}\((true|false)(;true|;false)*\)\[\d(,\d)*\]$");
if (pattern.IsMatch(s))
{
// s is valid
}
If you want anything inside (), you can use following regex:
#"^\d{1,3}:[a-zA-z]{1,10}\([^:\(]*\)\[\d(,\d)*\]$"
I am trying to use a regex to get the value after a character. In this case, the string is m325 and I need to get whatever is after the m.
Can anybody tell me what is wrong with my code?
Regex rgMeter = new Regex("m(.+$");
intMeterID = Convert.ToInt32(rgMeter.Match(strID));
Update:
Thanks for all your answers...for some reason the regex "m(.+)$" is returning the m as well as the string I require. I have tried the Groups example and it returns the data that I want. Why do I need to use Groups to do this?
Apart from the missing ), you oversimplified it a bit. You need to do
Regex rgMeter = new Regex("m(.+)$");
intMeterID = Convert.ToInt32(rgMeter.Match(strID).Groups[1].Value);
(Possibly, you might want to add a check if the Match() matched or not.)
You are missing a closing ). Plus, if you are extracting a number you should limit yourself to digits only, Will avoid trying to parse a faulty string into integer in the next statement.
m(\d*)
"m(.+)$" - there wasn't closed (
Also, you can test it on: http://gskinner.com/RegExr/
What values can appear behind the "m" character?
If it's only an integer, the I should use the solution Shekhar_Pro provided..
If any character, go with the rest :)
The regex you require is /^m(.*)$/
Actually you should use \d or [0-9] if you want match digits.
/^m([0-9]*)$/
and
/^m([0-9]{3})$/
if there are always 3 digits
Looks like you missed the closing )
A simple "m\d*" should do this.. please show us whole string to see the case.