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From: otto@tukki.jyu.fi (Otto J. Makela)
Newsgroups: comp.lang.c,comp.os.msdos.programmer
Subject: Re: How do I SHORTEN a file without rewriting it?
Message-ID: <OTTO.90Nov6165632@tukki.jyu.fi>
Date: 6 Nov 90 15:56:32 GMT
References: <1162@bilver.UUCP> <747@csource.oz.au> <9505@jarthur.Claremont.EDU>
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In-Reply-To: dfoster@jarthur.Claremont.EDU's message of 2 Nov 90 23:48:53 GMT

In article <9505@jarthur.Claremont.EDU> dfoster@jarthur.Claremont.EDU (Derek R. Foster) writes:
   In article <747@csource.oz.au> david@csource.oz.au (david nugent) writes:
   >In <1162@bilver.UUCP> alex@bilver.UUCP (Alex Matulich) writes:
   >[how do I shorten a file ?]
   >Write zero bytes at that position. [MeSsy-DOS only solution]

   If this works, it isn't documented in the Microsoft C manuals I have.
   (And believe me, I searched!) After SEVERAL calls to Microsoft,
   (Two seperate people told me it couldn't be done from either within C or
   through DOS! I thought these people were supposed to be knowledgeable!)
   and a great deal of loud cursing, I was finally led to the chsize()
   function. This seems to be the only way of doing this from within
   Microsoft C, (And I suspect Turbo C as well.) If you are using
   streams, you will probably have to close your stream, reopen the file
   using handles, chsize() it, close it again, reopen using streams...
   What a mess. But it works, and is better than (in my case) copying
   a 20-meg file to a shorter length...

Look at the fileno() function in your manual (your library does have it,
I hope).  Returns the file descriptor (handle as it's called in MeSsy-DOS)
for the given stream.
--
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