On 9/19/00 2:51 AM, Scott Raney wrote:
> On Mon, 18 Sep 2000, James Parker wrote:
>
>>> On 18/9/00 4:45 pm, James Parker <[EMAIL PROTECTED]> wrote:
>>>
>>>> I'm reading a binary file a character at a time and looking for the
>>>> end-of-file marker so I know when to stop reading but the read terminates
>>>> before the entire file is read. There seems to be an eof marker in the
>>>> file that is not at the end of the file. CharToNum(EOF) returns a 4
>>>> which could appear at places other than the end of the file, right?
>>>>
>>>> Is the following correct?
>>>>
>>>> repeat forever
>>>> read from file sourcefile for 1 character
>>>> if the result is "eof" then exit repeat
>>>> put it into var1
>>>> end repeat
>>>
>>> I'm not quite sure why you want to do this, why not:
>>>
>>> read from file tSourceFile until eof
>>
>>
>> Thanks for your prompt reply, Kevin.
>>
>> This is how I started reading files but discovered that when I read large
>> files this way it hangs the MetaCard application.
>
> How large were the files, and on what platform? You should be able to
> read just about anything on a Win32 or UNIX systems, but reading files
> larger than a few MB on a Mac is probably not a good idea unless you
> have a large amount of RAM.
Is this applicable to all MetaCard disk I/O commands on Mac, or just
effecting:
put url "binfile:thefile.txt"
where it really reads the entire file into RAM?
>>> If you really do want to read char by char for some reason, you need to
>>> alter line 3 above to be:
>>>
>>> if it is eof then exit repeat
>>>
>>> Eof is a constant so can't be put in quotes.
>>
>> The reason I did it this way is that the MetaCard documentation for
>> result says 'Returns a string describing the status of the last find, go,
>> open, send, or file operation command.' and for read it says that 'The
>> result will be set to the string eof when an end-of-file was encountered
>> during the read, or to an error message if some other error occured. An
>> empty result indicates a successful read.'
>
> You did the right thing. When you don't want to put EOF in quotes is
> when you're passing it to the read command (e.g., "read from file x
> until eof").
>
>>> Note that reading and writing to files is (except in a few special cases)
>>> generally easiest done with the URL commands. E.g.:
>>>
>>> put url ("binfile:"&tSourceFile) into tVariable
>>
>> Let me give this a try and see what happens.
>
> This is functionally equivalent to "read until eof", it just saves a
> couple of lines of script for opening and closing the file. Same
I must say "put url" has been my favourite command dealing with files.
However, I am planning to use the more traditional "open" and "seek" command
to deal with large files. My only problem is how find out the current
reading/writing position of the file.
Thanks.
LiangTyan Fui
> restrictions apply to the hardware/OS, though: You should only do this
> if you're sure that there's enough virtual memory available on the
> target system.
> Regards,
> Scott
>
>>> Regards,
>>>
>>> Kevin
>>>
>>>> Thanks,
>>>> Jim Parker
>>>
>>> Kevin Miller <[EMAIL PROTECTED]> <http://www.runrev.com/>
>>> Runtime Revolution Limited (formerly Cross Worlds Computing).
>>> Tel: +44 (0)131 672 2909. Fax: +44 (0)1639 830 707.
>>>
>>>
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>>
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>>
>
> ********************************************************
> Scott Raney [EMAIL PROTECTED] http://www.metacard.com
> MetaCard: You know, there's an easier way to do that...
>
>
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>
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