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kristofvdw@matt.es 11-07-2005 01:08 PM

Identifying extended ASCII subset
 
Hi,

I have to treat a given text file, but haven't got a clue which
extended ASCII set it is using.
Opening the file in Windows' Notepad or in DOS, all accented letters
and symbols are wrong.
Any idea how to identify the subset used?
Is there some text editor which can cycle easy through all known
subsets, or even better: cycle subsets automatically until found a
given test-string with some accents and symbols?
If someone knows a solution which involves VB, C++, XML or whatever
please don't hesitate sharing it with me.

TIA,
K


Jim Mack 11-07-2005 02:39 PM

Re: Identifying extended ASCII subset
 
kristofvdw@matt.es wrote:
> Hi,
>
> I have to treat a given text file, but haven't got a clue which
> extended ASCII set it is using.
> Opening the file in Windows' Notepad or in DOS, all accented letters
> and symbols are wrong.
> Any idea how to identify the subset used?
> Is there some text editor which can cycle easy through all known
> subsets, or even better: cycle subsets automatically until found a
> given test-string with some accents and symbols?



If you expect a computer to do this for you, you're probably dreaming. Since the actual character codes don't change, only the visual representations, someone has to look at the result to make a judgement.

If you have OCR code that will work on a memory bitmap, you could conceivably draw out the characters using a given code page and try to OCR the result, but even then I don't see any way to tell one 'close' result from another.

What is it you need to do to the text, that requires you to know what the codes represent?

--

Jim Mack
MicroDexterity Inc
www.microdexterity.com


Victor Bazarov 11-07-2005 02:54 PM

Re: Identifying extended ASCII subset
 
On Mon, 07 Nov 2005 05:08:37 -0800, kristofvdw wrote:
> I have to treat a given text file, but haven't got a clue which
> extended ASCII set it is using.


Files contain bytes. Bytes are numerical values. There are no ASCII sets
or extended ASCII sets, AFA files are concerned. It's all in _our_ minds.
To make your program understand and tell one set from another, you need to
basically *teach* it the same "algorithm" _you_ are using to differentiate
those sets.

> [...]


And avoid cross-posing to too many newsgroups at once. It makes your post
that more irrelevant in many newsgroups.

V

Richard Tobin 11-07-2005 03:56 PM

Re: Identifying extended ASCII subset
 
In article <1131368917.348353.5400@o13g2000cwo.googlegroups.c om>,
<kristofvdw@matt.es> wrote:
>I have to treat a given text file, but haven't got a clue which
>extended ASCII set it is using.
>Opening the file in Windows' Notepad or in DOS, all accented letters
>and symbols are wrong.
>Any idea how to identify the subset used?


You can get Mozilla's character set guesser:

http://www.mozilla.org/projects/intl/chardet.html

There's a Java version too:

http://jchardet.sourceforge.net/

-- Richard

Peter Flynn 11-07-2005 09:01 PM

Re: Identifying extended ASCII subset
 
kristofvdw@matt.es wrote:

> Hi,
>
> I have to treat a given text file, but haven't got a clue which
> extended ASCII set it is using.
> Opening the file in Windows' Notepad or in DOS, all accented letters
> and symbols are wrong.
> Any idea how to identify the subset used?
> Is there some text editor which can cycle easy through all known
> subsets, or even better: cycle subsets automatically until found a
> given test-string with some accents and symbols?
> If someone knows a solution which involves VB, C++, XML or whatever
> please don't hesitate sharing it with me.


Open the file is a hexadecimal editor, pick some of the characters,
and use the Unicode charts (www.unicode.org) to identify what
encoding they are.

Or just ask whoever created it.

///Peter


kristofvdw@matt.es 11-08-2005 11:01 AM

Re: Identifying extended ASCII subset
 
mmm, you're right there; automating would be quite difficult and
probable even take longer than browsing the sets manually... any tool
you know to do so?

The data are our clients, gotten through legacy-software. Now I'm
putting the data in an Oracle DB, but it's impossible to get
information on which coding the program uses. Lots of names and
addresses have accents in them, which we can't afford to loose.


kristofvdw@matt.es 11-08-2005 11:08 AM

Re: Identifying extended ASCII subset
 
Thanks for the suggestion, I'll look into that.
Unfortionately, the universal_charset_detector isn't built yet, and
doesn't support rare sets, so I don't have much hope...


Jim Mack 11-08-2005 12:01 PM

Re: Identifying extended ASCII subset
 
kristofvdw@matt.es wrote:
> mmm, you're right there; automating would be quite difficult and
> probable even take longer than browsing the sets manually... any tool
> you know to do so?
>
> The data are our clients, gotten through legacy-software. Now I'm
> putting the data in an Oracle DB, but it's impossible to get
> information on which coding the program uses. Lots of names and
> addresses have accents in them, which we can't afford to loose.


Do you know for sure that there is more than one character-set encoding in use? And what would you change these to, once you knew what they represented?

Is this something you have to do just once, or is there a continuing need? For a one-time use, manually cycling through your choices may not be that painful.

If this is truly an 'extended ASCII' file, which might be a legacy DOS file, you could try an OEM character set. There are several OEM code pages, but CP 437 is the most common. Just using an OEM font (like Ms Terminal or FoxPrint) will reveal whether this is the case. If it is, then applying the API OemToCharBuff will do the translation into the current code page.

--
Jim

kristofvdw@matt.es 11-08-2005 12:08 PM

Re: Identifying extended ASCII subset
 
Apparently, the problem is worse than expected.
As Peter suggested, I took a look at the hex-codes.
I discovered some apparent extended characters refered to the basic
ASCII codes!
For example, a name with "" (code 199/hex C7) got exported as "G"
(code 71/hex 47).
So, when exporting from an apparent extended ASCII set, it uses a basic
ASCII set, overlapping extended codes at 128 (for the example:
199-128=71).
What a moron! The programmer who managed to achieve this!

Thanks all for your contributions, I now have to search for the
original programmer and kill him...


Alan J. Flavell 11-08-2005 12:13 PM

Re: Identifying extended ASCII subset
 
On Tue, 8 Nov 2005, Jim Mack wrote, seen in comp.text.xml:

> If this is truly an 'extended ASCII' file, which might be a legacy
> DOS file, you could try an OEM character set. There are several OEM
> code pages, but CP 437 is the most common.


In the USA, perhaps; but CP850 is the DOS codepage for a multinational
situation, at least in basically latin-1 usage - and had been for
quite some time.

[f'ups proposed]


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