Parsing multi sections of a text file using regex in C#

Question

I would like to parse a text file with content that looks something like below:

START-OF-DATA
#100846105
START SECURITY|US912810DZ85|CBBT|
## in: 20150430_14         


        

Answer 1

You can read the file line by line, and filter out the lines you do not want. Also, the tick values and ids can be collected into a list of strings.

Sample code:

var res = string.Empty;
var ids = new List<string>();
using (var sr = new StreamReader(filepath, true))
{
    var s = "";
    while ((s = sr.ReadLine()) != null)
    {
       if (s.StartsWith("START-OF-DATA"))
       {
           while (!s.StartsWith("END-OF-DATA"))
           {
              if ( !s.StartsWith("START SECURITY") &&
                   !s.StartsWith("##") &&
                   !s.StartsWith("END SECURITY"))
                   {
                      res += s + System.Environment.NewLine;
                   }
              if (s.StartsWith("#") && !s.StartsWith("##"))
                   ids.Add(s);
               s = sr.ReadLine();
            }
            res += s;
       }
   }
}

Output:

START-OF-DATA
#100846105
04/30|15:00:00|B|118.640625||| |A|118.703125||| ||
04/30|14:59:54|B|118.6328125||| |A|118.6953125||| ||
04/30|14:59:52|B|118.6328125||| |A|118.6953125||| ||
04/30|14:59:23|B|118.6328125||| |A|118.6953125||| ||
04/30|14:59:20|B|118.6328125||| |A|118.6953125||| ||
#100846111
04/30|15:00:00|B|124.75||| |A|124.828125||| ||
04/30|14:59:55|B|124.75||| |A|124.8203125||| ||
04/30|14:59:53|B|124.7421875||| |A|124.8203125||| ||
04/30|14:59:45|B|124.7421875||| |A|124.8125||| ||
04/30|14:59:43|B|124.7421875||| |A|124.828125||| ||
04/30|14:59:27|B|124.7421875||| |A|124.8125||| ||
04/30|14:59:24|B|124.7421875||| |A|124.828125||| ||
04/30|14:59:22|B|124.7421875||| |A|124.8125||| ||
04/30|14:59:20|B|124.7421875||| |A|124.828125||| ||
04/30|14:59:13|B|124.7421875||| |A|124.8125||| ||
END-OF-DATA

Then, if you have multiple blocks to read, just create a list of strings to store the ress in, add right after res += s;.

Answer 2

Here is a simple parser

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;


namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Section> sections = new List<Section>();
            string input =
               "START-OF-DATA\n" +
               "#100846105\n" +
               "START SECURITY|US912810DZ85|CBBT|\n" +
               "## in: 20150430_14:59:00 to 20150430_15:00:00 [13 (New York-DST)]\n" +
               "## out:20150430_14:59:00 to 20150430_15:00:00 [13 (New York-DST)]\n" +
               "04/30|15:00:00|B|118.640625||| |A|118.703125||| ||\n" +
               "04/30|14:59:54|B|118.6328125||| |A|118.6953125||| ||\n" +
               "04/30|14:59:52|B|118.6328125||| |A|118.6953125||| ||\n" +
               "04/30|14:59:23|B|118.6328125||| |A|118.6953125||| ||\n" +
               "04/30|14:59:20|B|118.6328125||| |A|118.6953125||| ||\n" +
               "END SECURITY|US912810DZ85|0|\n" +
               "#100846111\n" +
               "START SECURITY|US912810EA26|CBBT|\n" +
               "## in: 20150430_14:59:00 to 20150430_15:00:00 [13 (New York-DST)]\n" +
               "## out:20150430_14:59:00 to 20150430_15:00:00 [13 (New York-DST)]\n" +
               "04/30|15:00:00|B|124.75||| |A|124.828125||| ||\n" +
               "04/30|14:59:55|B|124.75||| |A|124.8203125||| ||\n" +
               "04/30|14:59:53|B|124.7421875||| |A|124.8203125||| ||\n" +
               "04/30|14:59:45|B|124.7421875||| |A|124.8125||| ||\n" +
               "04/30|14:59:43|B|124.7421875||| |A|124.828125||| ||\n" +
               "04/30|14:59:27|B|124.7421875||| |A|124.8125||| ||\n" +
               "04/30|14:59:24|B|124.7421875||| |A|124.828125||| ||\n" +
               "04/30|14:59:22|B|124.7421875||| |A|124.8125||| ||\n" +
               "04/30|14:59:20|B|124.7421875||| |A|124.828125||| ||\n" +
               "04/30|14:59:13|B|124.7421875||| |A|124.8125||| ||\n" +
               "END SECURITY|US912810EA26|0|\n" +
               "END-OF-DATA\n";


            StringReader reader = new StringReader(input);
            string inputLine = "";
            Section newSection = null;
            while ((inputLine = reader.ReadLine()) != null)
            {
                inputLine = inputLine.Trim();
                if (inputLine.StartsWith("#"))
                {
                    if (inputLine.Contains("in:")) continue;
                    if (inputLine.Contains("out:")) continue;
                    newSection = new Section();
                    sections.Add(newSection);
                    newSection.iD = inputLine.Substring(1);
                    newSection.data = new List<string>();

                }
                else
                {
                    if (inputLine.Substring(0, 3) == "END") continue;
                    if (inputLine.Substring(0, 5) == "START") continue;
                    newSection.data.Add(inputLine);
                }
            }

        }
        public class Section
        {
            public string iD { get; set; }
            public List<string> data { get; set; }
        }
    }

}