how can i be certain that a file has copied exactly?
kline at thought.org
Sun Dec 28 01:49:09 UTC 2008
On Sat, Dec 27, 2008 at 11:58:35PM +0200, Giorgos Keramidas wrote:
> On Sat, 27 Dec 2008 13:35:51 -0800, Gary Kline <kline at thought.org> wrote:
> > On Sat, Dec 27, 2008 at 02:58:06PM +0200, Giorgos Keramidas wrote:
> >> On Sat, 27 Dec 2008 01:40:13 -0800, Gary Kline <kline at thought.org> wrote:
[[ save the electrons!]]
> > Your code copies flawlessly. I noticed late last night that cmp uses
> > the same byte-by-byte cp and IIRC checks each to make certain they
> > bytes are identical. My copyFile() function simply used fopen, fgets,
> > and fputs. I yanked it from a program that copied files from ~/Mail
> > where the lines were around 80 bytes rather than in the thousands.
> > With few newlines. The gotcha got me, in other words! Thanks much
> > for the function!
> That's good news, because I didn't even compile it. I just wrote it in
> my mailer and hit send. I'm glad it worked :)
> For what it's worth, if you are not handling *text* files, fgets() and
> fputs() are probably a bad idea. They are line oriented, and they
> depend on the presence of '\n' characters. The concept of ``lines'' is,
> at best, ill defined for binary files. So it makes more sense to use
> either byte-for-byte copies and rely on stdio to do buffering, or to use
> some sort of custom buffer and fread()/fwrite() or plain read()/write().
Just got up from a nap [ and *coffee*]. Still, after last
night's until past 03.30 with TWO giggling teenagers, god
help me:) --never had sleepover when i was 13-- Anyway,
your comment about writing that from scratch brought to mind
something I've been pondering recently. I already have
several kinds of main() functions that let you go in various
directions. Input by re-direction, input from the cmdline,
even both. These save me typing maybe 20 to 50 lines. If
you enjoy typing and rewriting code rom scratch a zillion
times, fine, but at least I would rather use my ``prefab''
I also have some very simple and efficient string-matching
functions [[ for SHORT lines!! ]] and other thing we do very
often. It was (is?) throw-away code. Does it made sense to
have a place on the web where you can get these kind of
canned functions? I have perhaps 20 of these functions named
and tagged. This was, I believe, at least one idea behind
C++, but at least I have never seen any sites that offer C
or C++ functions to do ``X''.
Gary Kline kline at thought.org http://www.thought.org Public Service Unix
The 2.17a release of Jottings: http://jottings.thought.org/index.php
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