Regex problem

Question

Hi I want to filter text lines with regex but I couldnt be able to solve. Text is like below; ************************* this is sample 123.123.123.123 pe 1 34.34.34.34 3.3.3.3 te another text anether text too 45.45.45.45 ************************* I want to get the lines which has started with 2 space and continuing decimal character. How may I do this?

Vulpes · Answer

OK try this: using System; using System.Collections.Generic; using System.Text.RegularExpressions; using System.IO; class Test { static void Main() { string[] lines = File.ReadAllLines(yokzu.txt); List list = new List (); string regExp = @^ (\d{13}\.\d{13}\.\d{13}\.(\d{13}|0/24))( (pe|te)( \d{12})?)??$; foreach(string line in lines) { if (Regex.IsMatch(line regExp)) list.Add(line.TrimEnd('')); } foreach(string line in list) { Console.WriteLine(line); } Console.ReadKey(); } } I've changed the test file to: this is sample 123.123.123.123 pe 1 34.34.34.34 3.3.3.3 te another text anether text too 45.45.45.45 21.43.24.0/24 pe 24 33.10.24.0/24 The output was: 123.123.123.123 pe 1 34.34.34.34 3.3.3.3 te 45.45.45.45 21.43.24.0/24 pe 24 33.10.24.0/24

yokzu · Answer

Thanks a lot Vulpes it solved my problem:)

Vulpes · Answer

The reason why it's not filtering those lines is because I only allowed for a possible 0/24 subnet suffix in the previous regular expression. If you change it to this then it should filter any suffix: string regExp = @^ (\d{13}\.\d{13}\.\d{13}\.\d{13}(/\d{13})?)( (pe|te)( \d{12})?)??$;

yokzu · Answer

Thanks I solved the comma problem Vulpes. But I have problem with regex. For example regex doesnt filter the lines below:( 18.56.11.44/20 pe 24 18.56.11.3/20 pe 24 All decimal digits are between 0-255. Actually they are Ip addresses.

Vulpes · Answer

That's why I've included a call to TrimEnd('') before adding the line to the list. If the line doesn't end in a comma this method will have no effect. I tried to filter it out using the regular expression itself by replacing ?$ with a positive lookahead (?=?$) which in theory should match strings ending with a comma but not include the comma in the result. However for some unknown reason it didn't work - the same lines were returned but with the comma still in tact :(

yokzu · Answer

Thanks Vulpes its working but with a litle problem. Is there any way to filter commas which end of the lines? Some of them has comma but some of them hasnt.

yokzu · Answer

Hi Vulpes -Yes the line should start with 2 spaces -Line has Ip address and subnet informations like below **************** 21.43.24.0/24 pe 24 33.10.24.0/24 **************** -There are only two strings pe and te. and after them one space and two or one digit decimal text. Like below (And maybe comma..Some of them hasnt.) ***************** 21.43.24.0/24 pe 24 *****************

Jignesh Trivedi · Answer

hi Try... string[] lines = System.IO.File.ReadAllLines(@E:\JTtest.txt); var targetline = lines.Where(file => file.StartsWith( ) && Regex.IsMatch(file.Trim() @[0-9.]+$)); example ************************* this is sample 123.123.123.123 pe 1 34.34.34.34 3.3.3.3 te another text anether text too 45.45.45.45 ************************* it will only filter  45.45.45.45 hope this will help you.

Vulpes · Answer

A lot more clarification is needed please: 1. Should the line begin with one space (you said two originally) or with either one or two spaces? 2. Will there always be four sets of digits separated by periods will these sets always contain the same number of digits and will there only be one two or three digits in each set? 3. What are the rules about 'pe' and 'te' and any following digits?

yokzu · Answer

Thanks for your answers but they are not exactly match for me. I'll try to explain it. In the text file there are lots of lines. Some of them ending with comma some of them not. For example I want to filter these lines in the sample text above. ********************* 123.123.123.123 pe 1 34.34.34.34 3.3.3.3 te 45.45.45.45 ******************** Rules are ; -Line should start with space and a decimal string -Should filter till end of line -And if line has comma at the end it should be filtered too. I hope I make myself clear.

Jignesh Trivedi · Answer

hi your requirement is not much clear but try... string[] lines = System.IO.File.ReadAllLines(@E:\JTtest.txt); var targetline = lines.Where(file => file.StartsWith( ) && Regex.IsMatch(file.Trim() @^(\d+\.\d+\.\d+\.\d+)()$)); foreach (var mys in targetline) { Console.Write(mys); } I have create code that filter record which are start with 2 space and match pattern ddd.ddd.ddd.ddd hope this will work for you. let me know if you required more help.

Vulpes · Answer

Try this: using System; using System.Collections.Generic; using System.Text.RegularExpressions; using System.IO; class Test { static void Main() { string[] lines = File.ReadAllLines(yokzu.txt); List list = new List (); string regExp = @^ \d; foreach(string line in lines) { if (Regex.IsMatch(line regExp)) list.Add(line); } foreach(string line in list) { Console.WriteLine(line); } Console.ReadKey(); } }