If you do that, won't you limit your input to Unicode files?

I think that one approach would be to use a StreamReader to
automatically detect the encoding of the file for you, and then read
the first 1K or so, counting how many characters return true for the
Char.IsLetterOrDigit method and comparing that to the total number of
characters.

It still won't be perfect, but you should be able to come up with a
reasonably good heuristic regarding what the ratio of alphanumeric
characters to other characters you would expect to see in a text file.

Of course, you can still include the user in the determination.  For
example, run the above test and if the file passes go ahead and use it,
but if it fails provide the user with a chance to override your
analysis.  You could even do this just as you suggest: provide a brief
preview of the initial part of the file to the user so that they can
visually decide whether it's a file they want treated as text.

Caveat: I have basically no experience with non-alphabetic languages,
and I don't know if in a non-alphabetic language a word character would
be considered a "letter" for the purpose of the above test.  If that's
important to you, you'll want to verify that and/or find a form of
classification that will correctly detect those characters as text.

Pete

Pete --

Pete --

Pete --

Using a DataGrid is very thought provoking. Still beyond my beginner
status capabilities. The curiosity seed is however now planted and
when the right combination of skill accumulation and need occurs I
shall try to baby step my way into the Grid.

My data file picker/viewer is now working. :)

I went back to the RichTextBox usage. My attempts at "painting" text
just caused me headaches and errors. Mixing EventArgs from my ListView
object with PaintEventArgs to control the graphics is beyond my
understanding ... although I gave it many hours of effort.

What ended up being VERY helpful is >>

1) Using StreamReader.   ( ** Thank You ** for the suggestion !! )
2) Setting >> rtb.WordWrap = false; (rtb = RichTextBox object)
3) Implementing FontDialog for selecting the text attributes.
4) Using a line reading counter to limit loading too large of files.
5) Read only is set. Background is gray and I am ok with that.

The top left of my FilePicker is a Directory TreeView and the top
right is a File ListView. This top half acts like a weak version of
FileExplorer. The bottom splitter panel is a RichTextBox that is now
behaving very well!!

When I click on a huge binary data file >> the RichTextBox shows a
fast response 40 lines of gibberish. No big deal and NOT having the
entire file load is NICE! That rtb.LoadFile() can be a pain.

Usually viewing 40 lines is plenty for me to validate that the correct
parameter file is indeed selected ... so it's a winner. I have some
future enhancement ideas too. A two thumb sliding bar controller to
select where to start and end file input is one such idea. I'd like
better list control too. Currently my File ListView does not sort by
variable columns. I'd like to be able to sort by time in addition to
the current ascending FileName ordering.

Amazing how difficult these simple tasks are for beginners. And how
IMPOSSIBLY difficult these tasks use to be. Wow!! I can only shake my
head at the effort needed to duplicate my WinForm 2.0 functionality
using older methods. Ouch!!

Single screen file selection and quick viewing without concern for
accidentally editing it is sweet. A very functional tool I shall use
aplenty.

For emphasis >> All the comments I received were helpful and kept me
digging when I felt like waving the white flag. Now I am all smiles.
Dare I look at my long list of other projects? Yikes !!!

A great day to all.

-- Tom