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  1. using System;
  2. using System.Text.RegularExpressions;
  3.  
  4. public class Test
  5. {
  6. 	public static void Main()
  7. 	{
  8. 		    string pattern = @"^\s*(\d{1,2}-\d{1,2}-\d{2,4})((?:\r?\n(?:(?=\s*\1)|(?!\s*\d{1,2}-\d{1,2}-\d{2,4})).*)*)";
  9.             string input = @" 13-08-2020
  10.  data day1 
  11.  13-08-2020 
  12.  data day1  
  13.  13-08-2020 
  14.  data day1 
  15.  14-08-2020
  16.  data day2";
  17.             string result = Regex.Replace(
  18.                     input, pattern, match =>
  19.                         match.Groups[1].Value + Regex.Replace(
  20.                             match.Groups[2].Value, @"^[^\S\r\n]*(?:\d{1,2}-\d{1,2}-\d{2,4}\s*)?", ""
  21.                             , RegexOptions.Multiline
  22.                         )
  23.                         , RegexOptions.Multiline
  24.                     );
  25.             Console.WriteLine(result);
  26. 	}
  27. }
Success #stdin #stdout 0.06s 21236KB
comments (?)
stdin 
Standard input is empty
stdout 
13-08-2020
data day1 
data day1  
data day1 
14-08-2020
data day2
https://ideone.com/Bn3oYa
language:
C# (gmcs 5.20.1)
created:
5 years ago
visibility:
public

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