How to order file lines based on creation date

February 22, 2023

So I have a text file that I need to order its rows by Date and Time as show in the attached screenshot column and I am not sure how

any idea please?

Screenshot

this is what i tried so far

File
    .ReadLines(newfile)
    .OrderBy(line => DateTime.TryParseExact(
        line.Split("  ",StringSplitOptions.RemoveEmptyEntries),
        "yyyy MMM d H:m:s.fff", CultureInfo.InvariantCulture, 
        DateTimeStyles.AssumeLocal, out var dt) 
            ? dt
            : DateTime.MaxValue);

>Solution :

You should extract date, parse it and then order by this date.
I can’t see what is the delimeter in your file. If it’s tabulation '\t':

using System.Globalization;
using System.Linq;

...

// Assuming myFile is IEnumerable<string>
var sortedLines = myFile
  .OrderBy(line => DateTime.TryParseExact(
      line.Split('\t', StringSplitOptions.RemoveEmptyEntries)[1],
     "yyyy MMM d H:m:s.fff",
      CultureInfo.InvariantCulture,
      DateTimeStyles.AssumeLocal, out var dt)
        ? dt
        : DateTime.MaxValue); // Incorrect dates will be in the end

If the delimiter is a double space " " then

var sortedLines = myFile
  .OrderBy(line => DateTime.TryParseExact(
      line.Split("  ", StringSplitOptions.RemoveEmptyEntries)[1],
     "yyyy MMM d H:m:s.fff",
      CultureInfo.InvariantCulture,
      DateTimeStyles.AssumeLocal, out var dt)
        ? dt
        : DateTime.MaxValue);

If myFile is a name of the file you should put it as

using System.IO;

...

var sortedLines = File
  .ReadLines(myFile)
  .OrderBy(...);

Edit: If myFile is FileStream you, technically, can enumerate it like this

static IEnumerable<string> FileLines(FileStream stream) {
  using StreamReader reader = new StreamReader(stream, leaveOpen: true);

  for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
    yield return line;
}

and then

var sortedLines = FileLines(myFile)
  .OrderBy(...);

but I doubt if you really want Stream here

Edit2: If we don’t know what the delimiter is (in the worst case it is space) we can match date with a help of regular expression:

  using System.Text.RegularExpressions;

  ...

  Regex regex = new Regex("[0-9]{4} [A-Z][a-z]+ [0-9]{1,2} [0-9:.]+");

  ...

  .OrderBy(line => DateTime.TryParseExact(
      regex.Match(line).Value ?? "",
     "yyyy MMM d H:m:s.fff",
      CultureInfo.InvariantCulture,
      DateTimeStyles.AssumeLocal, out var dt)
        ? dt
        : DateTime.MaxValue);