RE: [Boost-Users] [crc] Simple example please

From: Alex Henderson (Alex.Henderson_at_[hidden])
Date: 2003-06-10 05:38:05

Superb!

Thanks,
Alex

> -----Original Message-----
> From: Vladimir Prus [mailto:ghost_at_[hidden]]
> Sent: 10 June 2003 06:08
> To: boost-users_at_[hidden]
> Subject: [Boost-Users] [crc] Simple example please
>
>
> Hi Alex,
>
> > I'd like to calculate a value for a cyclic redundancy check (crc) for a
> > number of files.
> >
> > This isn't going to be transmitted anywhere, I simply want to
> compare the
> > values to see whether the files are exactly the same. I know I
> can simply
> > check byte for byte, but I've got a few thousand files and it's
> easier to
> > calculate the crc for each and see whether any are the same first.
>
> Here's the function that I use for the same purpose. Might not be optimal,
> but works:
>
> unsigned file_crc(const string& name)
> {
> #if defined(__GNUC__) && __GNUC__ < 3
>     ifstream ifs(name.c_str(), ios::binary);
> #else
>     ifstream ifs(name.c_str(), ios_base::binary);
> #endif
>     if (!ifs)
>         return 0;
>     else {
>         using namespace boost;
>
>         crc_32_type crc32;
>         int c;
>         while( (c = ifs.rdbuf()->sbumpc()) != -1)
>              crc32.process_byte(char(c));
>         return crc32.checksum();
>     }
> }
>
>
> I believe some example of this kind should be included... Daryle, what do
> you think?
>
> HTH,
> Volodya
>
>
>
>
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