| Re: reading a ninary file [message #46863] |
Mon, 09 January 2006 05:02  |
Klaus Scipal
Messages: 45
Registered: November 1997
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Member |
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Hi
I am not a specialist in character encoding but I guess you have to find out
how it was written. Which encoding was used to convert the characters to a
byte?
Characters are normally encoded in ASCII format which knows 128 characters.
As computers store data in bytes (i.e. 8 bits) there is room to store
another set of 128 characters, i.e. an extended character set. In practice,
there are a number of different extended character sets for example for
math symbols or extension characters for non-English languages. And to make
it even more difficult there are also other encoding systems then ASCII, for
example UNICODE.
I don't know if this is your problem but unless you don't know how the data
was encoded it will be difficult to "decode" it. I also don't know if the
different character sets are compatible and how IDL converts bytes to
characters. That's something you have to find out yourself. For more details
on character binary encoding check out
http://www.cs.tut.fi/~jkorpela/chars.html#examples
Of course a trial and error method would be to read out the byte and go into
the standard conversion tables and look what makes most sense.
Klaus
<claire.maraldi@gmail.com> wrote in message
news:1136798479.995043.160620@g44g2000cwa.googlegroups.com.. .
> Hello,
>
> I have to read a binary file containing long, fix and string variable
> type. I know that the string variable type are coded only on one byte
> (this have been confirmed by someone in the laboratory, and even if I
> try more bytes there is an "encountoured before end of file" error...).
> So I have tried to convert only one byte, and the results are amazing
> characters like "_-", "_"....
> I know that is not a problem of discrepency when the binary file is
> read because long and fix variable type are well converted (wether they
> are placed before or after string).
>
> Could explain me what exactly happen please ?
> Thank you
>
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