Writing (1) Digit To The End Of A Dos File (AREV Specific) [Revelation On-Line Wiki]

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At 17 MAY 2000 09:38:20PM Jim Dierking wrote:

AREV Specific

Well Don was right, xlating and writing a dos file works great

unless the variable goes over the 64k limit, which happened.

I used the code Aaron recommended to obtain the length of the

dos file. "Length=Dir('f:\arev3_1\datavol\export.txt')"

How can I write a null value to the last digit of the DOS file?

TIA for the help, Jim Dierking

At 17 MAY 2000 10:21PM Larry Wilson - TARDIS Systems, Inc. wrote:

something like:

* open the DOS file

CurPos=0

Done=0

loop
OSBREAD Chunk from DosFileVar at CurPos LENGTH 64000
* read 64K chunks

* Check status here - look at the R/Basic book

* set EOF if end of file
if EOF then
   CurPos += LEN(Chunk)
   Done=1
end else
   if Chunk then
      CurPos += LEN(Chunk)
look at Steve Smith's bugs page at:
      [url=http://www.ozemail.com.au/~stsm/top5.htm]Steve's Bug List[/url]
this checks for a bug in AREV
   end else
      CurPos -= 1
for some reason, EOF was missed on the last read, but this

is the end, so get the actual last pos
      Done=1
   end
until Done do

repeat

OSBREAD Chr from DosFileVar at CurPos LENGTH 1

if Chr=CHAR(26) then

* do you want to overwrite EOF?

* if so, just write, else CurPos -= 1 then write here

end else
 if you want to overwrite the last char, write at CurPos else
 CurPos += 1
 write whatever you want
 OSBWRITE newChar on DosFileVar at CurPos
end

be sure to look at Steve's remark.

tardis_systems@yahoo.com

http://AdvancedRevelation.com

(the icon below is real-time; if I'm not on, it asks to take a message

if I ring for a chat, you'll get a floating box that says to click

for a chat.)

At 17 MAY 2000 11:17PM Larry Wilson - TARDIS Systems, Inc. wrote:

Of course, if you don't need to look for anything else in the file, you could just do an INITDIR and DIR() and get the filezie then do a OSBREAD testchar from DosFileVar at FileSize-1 LENGTH 1 (remember that os OSBREAD, the file starts at 0, not 1) Then you don't need a loop.

At 18 MAY 2000 01:21AM Jim Dierking wrote:

Thanks for the help. Here's what worked…Jim

OSOPEN "UPS.TXT" TO UPS ELSE STOP

OSBWRITE "" ON UPS AT (Dir('f:\arev\UPS.txt') - 1)

OSCLOSE UPS

At 18 MAY 2000 01:39AM Larry Wilson wrote:

A few lines less than my first suggestion - nice succinct code.

Would you please send me your email address?

I thought that was you on the system around midnight but wasn't sure enough to try to trigger a chat (it's interesting what that little icon does!)

Later,

Larry

At 18 MAY 2000 09:16AM Don Miller - C3 Inc. wrote:

Just to be safe, check for the MOD 21930 bug before doing the read/write. See Steve Smith's top 5 AREV bugs. If you're at the magic number, back up one byte and read 1 byte. Then append your data to that byte and do the OSBWRITE there. E.G.

* COMPUTE BYTE POSITION TO WRITE AT AND STORE IT IN BYTE_POS

* CHECK FOR THE BAD PLACE PER STEVE AND SET FOOBAR TO 1 ELSE FOOBAR=0

IF FOOBAR THEN
BYTE_POS-=1
OSBREAD HUNK FROM WHATEVER_FILE AT BYTE_POS,1
HUNK:=MY_BYTE
OSBWRITE HUNK ON WHATEVER_FILE AT BYTE_POS
END ELSE
OSBWRITE MY_BYTE ON WHATEVER_FILE AT BYTE_POS
END

HTH

Don Miller

C3 Inc.

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