What is a line in a textfile?

Watching this post in another thread, I suddenly remembered once I tried something similar and got some empty lines. This prompted me to try an experiment:
Are the following equivalent:
* File.ReadAllLines(filename)
* File.ReadAllText(filename).Split(Environment.NewLine) '(Or ControlChars.CrLf - gives same result)
and does any of them actually split on Carriage Return followed by Linefeed and only there?

Surprisingly I found that the answer was no to both questions - which prompted me to question: what is a line in a textfile? I've allways assumed it had to end with CrLf.

File.ReadAllLines(filename) will split on Lf, Cr and CrLf (maybe more - haven't tested all controlchars)
File.ReadAllText(filename).Split(Environment.NewLine) seems to get confused and not act rationally at all!
File.ReadAllText(filename).Split() splits on whitespace causing CrLf to leave an undesired Lf string in the array.
File.ReadAllText(filename).Split(New Char() {ControlChars.Cr, ControlChars.Lf}) acts differently than all above.

I tested the examples and wrote my own version, of what I would expect for 'correct behaviour', with the following:

vb.net Code:

Dim filename As String = Path.Combine(Application.StartupPath, "Testing.txt")
 
        File.WriteAllLines(filename, New String() {"Carriage" & ControlChars.Cr & "return", "Nothing", _
                                                   "Line" & ControlChars.Lf & "feed", "Spa ce"})
 
        Dim lines() As String
 
        Console.WriteLine("Version 1: ----------------------")
 
        lines = File.ReadAllLines(filename)
        For Each line As String In lines
            Console.WriteLine(String.Format("'{0}'", line))
        Next
 
        Console.WriteLine("Version 2: ----------------------")
 
        lines = File.ReadAllText(filename).Split(Environment.NewLine)
        For Each line As String In lines
            Console.WriteLine(String.Format("'{0}'", line))
        Next
 
        Console.WriteLine("Version 3: ----------------------")
 
        lines = File.ReadAllText(filename).Split()
        For Each line As String In lines
            Console.WriteLine(String.Format("'{0}'", line))
        Next
 
        Console.WriteLine("Version 4: ----------------------")
 
        lines = File.ReadAllText(filename).Split(New Char() {ControlChars.Cr, ControlChars.Lf})
        For Each line As String In lines
            Console.WriteLine(String.Format("'{0}'", line))
        Next
 
        Console.WriteLine("Version 5: ----------------------")
 
        Dim total As String = File.ReadAllText(filename)
        Dim i As Integer = 0
        Dim length As Integer = 0
        
        While i < total.Length
            If total(i) = ControlChars.Lf Then
                If i > 0 AndAlso total(i - 1) = ControlChars.Cr Then
                    Console.WriteLine(String.Format("'{0}'", If(i > 1, total.Substring(i - length, length - 1), String.Empty)))
                    length = 0
                Else
                    length += 1
                End If
            Else
                length += 1
            End If
            i += 1
        End While

The question was: are lines in a textfile not supposed to be delimited by CrLf (for those who forgot it reading all that sheit)?.

Tom

it depends on how the file was saved.
textboxes use crlf + richtextboxes only use lf

Quote:

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Originally Posted by .paul.

it depends on how the file was saved.
textboxes use crlf + richtextboxes only use lf

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So there is no reason to maintain CrLf? And why was a new line ever implemented using 2 chars - old printers perhaps that had a different interpretation of Cr and Lf?

Anyways having 2 chars for a newline seems incredibly silly to me.

Cr and Lf are separate functions for printers. It was only on typewriters where both functions were integrated mechanically. But there's one very good reason to retain CrLf - the millions of text files written since the beginning of computing!

Quote:

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Originally Posted by dunfiddlin

Cr and Lf are separate functions for printers. It was only on typewriters where both functions were integrated mechanically. But there's one very good reason to retain CrLf - the millions of text files written since the beginning of computing!

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True! Tbh I didn't think about that. I guess changing formats and standards for files, hardware etc. is more difficult now than it has ever been.