| Dr John Stockto
Delphi Developer |
Wed, 18 Jun 1902 08:00:00 GMT
Re:Error 100 : Disk read error.
JRS: In article <MPG.1362914758ab101f989...@news.primenet.com> of Sat,
15 Apr 2000 14:47:06 seen in news:comp.lang.pascal.borland, Mike
QuoteCopeland <mrc...@primenet.com> wrote:
>> I am a collage student doing my project. I have a problem when
>> copying a file to another file. The source file was save in the harddisk
>> which I can open it using my display Program. Whenever I try to copy this
>> file, I always get this message (Error 100 : Disk read error). For your
>> infor, I using turbo pascal version 7 running on Pentium(Win98) and on Dos
>> enviroment. For your reference here are the copying program that I use.
>> Program Copyfile;
>> Uses Crt;
>> Type Account = Record
>> StudNo : 1..9999;
>> Name : String;
>> balance : Real
>> End;
>> Var OldAcct,NewAcct : Account;
>> NewStudents,Oldstudents : FILE OF Account;
>> Begin
>> Assign(Oldstudents,'Sample.Dat'); Assign(NewStudents,'List.Dat');
>> Reset(OldStudents); Rewrite(NewStudents);
>> While Not eof(OldStudents) Do
>> Begin
>> Read(OldStudents,OldAcct); NewAcct := OldAcct;
>> Write(NewStudents,NewAcct)
>> End;
> Close OldStudents); Close (NewStudents)
>> End.
> Even from this complete problem description, I can't be sure what the
>problem is. The code look okay (except you don't close the files after
>processing), and it should work. That fact that it doesn't leads me to
>believe you have a "mismatch" between your data definition (the record
>description) and the actual file data being processed. If there was less
>data on each file record than you've defined, you would indeed get an
>error such as you're receiving.
for (unnecessary) duplication. Every Read should eat 2+256+6 bytes (is
this a case where Reset needs a ", 1"? I suspect so) regardless of the
actual pattern of the data.
Quote> I am particularly interested in your declaration of "Name": you're
>using a string (which is actually "string[255]"), and I hardly think it's
>what you really have in the data file. I feel you should seek out and
>determine the precise data definition you're using and adjust your record
>definition accordingly.
Quote> BTW, if you are only _copying_ a data file, you don't need to do it at
>the record level, one at a time. It's far easier and better to use
>BlockRead/BlockWrite to do a generic copy of one file to another, and you
>don't have to deal with file content specifics...
write a note for the Malaysian Teacher's Journal, or whatever - we get a
lot from .my.
I did wonder, given Win98 & Crt, whether the "100" might be a typo for
"200".
As usual, he does not say whether Run-Time checks are on; nor at what
exact stage of the program the error occurs - the easy thing is to
insert Write statements, or single-step with the integrated de{*word*81} -
it should be at the read statement, of course.
Now if the record size is wrong, because of no "1" in Reset (Rewrite?)
or otherwise, and the input has a non-integer record count, then such
use of EoF means that a full read of a part record will be attempted ;
100 seems a likely error number for this.
=
In checking TP7, I just noticed something : ERATOST3.PAS has what I
thought was a Data Segment array as large as possible (given the program
also has 2 longints). It appears that when compiling to memory, it's
too big (error 49), but to disc is OK. Program was written with BP7;
IIRC, a difference in array size between MSDOS & DPMI modes too.
--
? John Stockton, Surrey, UK. j...@merlyn.demon.co.uk Turnpike v4.00 MIME. ?
<URL: http://www.merlyn.demon.co.uk/> TP/BP/Delphi/&c., FAQqy topics & links;
<URL: ftp://garbo.uwasa.fi/pc/link/tsfaqp.zip> Timo Salmi's Turbo Pascal FAQ;
<URL: http://www.merlyn.demon.co.uk/clpb-faq.txt> Pedt Scragg: c.l.p.b. mFAQ.
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