What is a line in a textfile?

[ThomasJohnsen]

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:

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