[Gambas-user] EOF problem

[Dimitris Anogiatis]

Ed,
if reading a text file and extracting information from it is what you're
trying to do, why not just use

tmp = File.Load(Fname)

File.Load is documented over here
http://www.gambasdoc.org/help/comp/gb/file/load

after loading the contents of Fname in tmp you can do your magic, without
using an OPEN statement and a loop
unless the file you're reading is a few megabytes, File.Load should be
sufficiently fast to cover your needs.

I am sure that there's more than one ways to skin a cat, and professionals
didn't exactly drop out of the sky one day
knowing everything about programming :) It takes practice and more practice
and even more practice :)  we all learn
in different ways and we're all here to help each other :) Whether we are
professionals,amateurs hobbyists or plain curious

As they say in my country, One hand washes the other and both wash the face
:)

Hope this helps
Regards,
Dimitris

On Mon, Apr 19, 2010 at 1:17 AM, Ed & Clare Kelm
<twopilots at ...2415...>wrote:

> Hi all:
>
> A couple of comments about the discussions below:
>
> 1.  The test program was written with EOF at the start, because the
> actual program I am working on has this structure, for reading in
> multiple lines of text:
>
> WHILE NOT EOF(tfile)
>    (bunch of code for reading the lines in and putting the data in the
> proper places)
> WEND
>
> CLOSE #tfile
>
> When that failed, I wrote the test program to see if I was actually
> sometimes getting an EOF immediately after opening the file, since the
> first thing WHILE does is test EOF.
>
> 2.  Clearing label1 after every button click is just a little
> insurance.  Given that things weren't working as expected, I wanted to
> make sure what I saw in label1 was new info, not something left from the
> previous button click.  I know that shouldn't be necessary, because the
> IF-THEN-ELSE structure will always write to the label - but then there
> shouldn't be an immediate EOF either.
>
> 3.  Using Fname like that is just a little habit I've developed.  It
> allows me to try a different file by commenting out one setting of Fname
> and writing a new one, without erasing the previous one.  And it makes
> the OPEN statement more compact and easy to read.  It is also sometimes
> useful to put such equates all in one place, so it's easy to find and
> change parameters, rather than rummaging around in the code.  You are
> correct, it is sort of a waste if I am only using the variable once.  In
> my actual program, Fname also gets used when the database gets modified
> and the file then has to be re-written.
>
> I am not a professional programmer, so I'm sure I have some ways of
> doing things that make professionals cringe!
>
> Thanks again for thinking about my problem!
>
> Regards,
>
> Ed K.
>
> Doriano Blengino wrote:
> > Les Hardy ha scritto:
> >
> >> Doriano Blengino wrote:
> >>
> >>
> >>> Les Hardy ha scritto:
> >>>
> >>>
> >>>
> >>>> Hi Ed,
> >>>> I figured it out.
> >>>> First of all, depending how the text file was emptied/created, the
> >>>> contents may not be truely empty.
> >>>> Gedit for example leaves the 0A (end-of-line) character in the 'empty'
> >>>> file. This is recognised by eof() as a character, so, end-of-file is
> not
> >>>> found.
> >>>> I am not sure if this can be considered a bug in Gambas, but it does
> >>>> mean an eof() is only good for preventing read errors, and is not
> >>>> reliable for testing if a file is empty.
> >>>>
> >>>>
> >>>>
> >>>>
> >>> Just breaking in to say that a file with a EOL in it is not an empty
> >>> file - it is a file with an empty line in it...
> >>>
> >>>
> >>>
> >> Your correct, I agree completely, but the original code Ed supplied, '
> >> IF Eof(tfile) ' cannot work , as it checks eof before a read.
> >> When I saw he was using eof() that way, and knowing empty files are not
> >> always empty, I thought I had found his problem, so I just added a bit
> >> of code that should have got around it.
> >>
> >> I am sure you will agree, that, whatever other problems he may have,  he
> >> needs not to use eof() the way he is.
> >>
> >>
> > Here is the original code. I think it is perfectly right:
> >
> >> PUBLIC SUB Button1_Click()
> >>
> >>    DIM tfile AS File
> >>    DIM Fname AS String
> >>
> >>    Fname = "/home/us/Documents/testdat.txt"
> >>
> >>    tfile = OPEN Fname FOR READ
> >>
> >>    label1.Text = ""
> >>
> >>    IF Eof(tfile) THEN
> >>       label1.Text = "EOF"
> >>    ELSE
> >>       LINE INPUT #tfile, label1.Text
> >>    END IF
> >>
> >>    CLOSE #tfile
> >>
> >> END
> >>
> >>
> >>
> > If eof() is not checked *before* reading, then when? I see only two
> > things I would not do (but it depends a lot). First, why use the "fname"
> > variable, if it is used only once... second, why set label1.text if that
> > .text will be anyway written shortly later?
> >
> > But, apart from these two very little things, that can also have some
> > good reason, the rest of the code is the only possible, I think. Note
> > also that label1.text can get 3 different values: "EOF" is the file is
> > empty; "" if the first line of the file is empty; something else if the
> > first line of the file contains some data. These three cases cover all
> > the cases we talked about (empty and not empty files), and I think our
> > friends know what they are doing.
> >
> > Of course I may be wrong, but that use of eof() seems to me fully ok.
> >
> > Regards,
> >
> >
>
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