Forum: Ruby Weird error while reading binary files

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Humm :. (Guest)
on 2006-12-22 04:24
Hello everyone!

I just started messing around with Ruby and so far it's been great.
Somehow I've stepped into some weird error I can't understand nor solve
it.. I've been trying to google about it but with no results..

Here's what's going on:
I've got a file structure which is like:
4 bytes - Number of entries
For number of entries : 300 bytes of information.. several integers,
longs, floats, strings...

If I do:

theFile = File.open('FilePath')

infoArray = Array.new

infoEntries = theFile.read(4).unpack('V')[0]
infoEntries.times do |i|
     infoArray[i] =
theFile.read(300).unpack('VA4V2FS4V12A24A8A32A32A32A32A32V8')
end


It will go fine until infoArray[33]. After that it won't work at all!
Let me make myself clear:

irb(main):002:0> theFile = File.open('FILEPATH')
=> #<File:FILEPATH>
irb(main):003:0> theFile.pos = 10244
=> 10244
irb(main):004:0> theFile.read(4)
=> "H\001\000\000"
irb(main):005:0> theFile.pos
=> 14340
irb(main):006:0>

See how it jumped positions?! That's odd.. Is there a file-size limit or
something like that? I'm under Windows, by the way...
Humm :. (Guest)
on 2006-12-22 04:30
I've tested it with and without unpack.. Several files.. And nothing.
I haven't tested the BinaryStructure thing class yet.. But I don't feel
like using it.. It shouldn't be needed, at least.

Thanks!

[sorry about the double post, accidentaly posted it before finishing it]
Joel VanderWerf (Guest)
on 2006-12-22 05:26
(Received via mailing list)
Mauricio Kishi wrote:
> theFile = File.open('FilePath')

On windows, you'll want

   theFile = File.open('FilePath', "rb")

to put the file in binary mode (doesn't convert \r\n to \n).
Humm :. (Guest)
on 2006-12-22 05:28
Joel VanderWerf wrote:
> Mauricio Kishi wrote:
>> theFile = File.open('FilePath')
>
> On windows, you'll want
>
>    theFile = File.open('FilePath', "rb")
>
> to put the file in binary mode (doesn't convert \r\n to \n).

Ooops, that was a mistake while writing the post! I'm already opening
the files on binary mode...
Humm :. (Guest)
on 2006-12-22 05:31
Joel VanderWerf wrote:
> Mauricio Kishi wrote:
>> theFile = File.open('FilePath')
>
> On windows, you'll want
>
>    theFile = File.open('FilePath', "rb")
>
> to put the file in binary mode (doesn't convert \r\n to \n).

OMG! No! Somehow I've missed it on the newest .rb files.. O_O"
Thanks a lot.. And sorry for such a stupid thing.
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