Subject: RE: fread fails when fopen is used without "rb"
From: [email-masked] (Bob McGowan)

14 Mar 1998 14:22:33 -0800
Message-ID: <[email-masked]>
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To: [email-masked]

Kevin,

This is a "feature" and even DOS tools (copy in particular) can have
this problem.  It comes from the fact that it text mode, a litteral
control-z character is entered in the file to mark EOF.
You can prove this by using copy to creat a text file (note <CR> just
means the return key):

	copy con file<CR>
	text<CR>
	text<CR>
	text<CR>
	^Z<CR>

and copy reports it copied one file.  If a binary file is opened in text
mode, the first control-z seen will now indicate EOF and the read will
return indicating EOF.  This is why the DOS copy command, when used to
paste together multiple binary file pieces, is run with the /b option,
to force binary mode:  copy /b xa+xb+xc file.zip

----
Bob McGowan
i'm bobmcgow at xstor dot com
Storage Dimensions, Inc.

-----Original Message-----
From: Kevin Cutts [mailto:[email-masked]]
Sent: Thursday, March 12, 1998 5:31 AM
To: [email-masked]
Subject: fread fails when fopen is used without "rb"

I made a mistake and opened a binary file using fopen("file","r"). Note
that 
I forgot to open it with "rb". When I read the file, I could only read
part
of the file: the read only suceeded for 2081 bytes of the 345K!
Believing
that I had made a coding mistake, I tried 'wc'. It agreed with my code:
they 
both 'think' the file has 2081 bytes. However emacs and ls both realize
the
file is much larger. (When I used a truly ascii file, the size worked
correctly. The code hack does work correctly under the Metrowerks
compiler.)

Does this seem like the correct behaviour? I can't trust wc because it
obviously opens as text. I looked in the faq without seeing anything
that
suggests this operation. In this case the failure was the best thing
that
could have happened because I discovered that the legacy unix code needs
some work around the binary/text problems. 

PS. I have the binary file which exhibits this problem if anyone is
interested. 

-- 
Kevin M. Cutts  IL02-2928               Motorola, Inc., CCR&D
Email ckc006 -at- email.mot.com         1301 E. Algonquin Rd.

Work (847) 576-9056                     Schaumburg, IL  60196

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