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

From: Louis Caston (louis_at_[hidden])
Date: 2003-06-10 07:12:44

This is very nice :)
  -----Original Message-----
  From: Alex Henderson [mailto:Alex.Henderson_at_[hidden]]
  Sent: Tuesday, June 10, 2003 6:38 AM
  To: Boost-Users_at_[hidden]
  Subject: RE: [Boost-Users] [crc] Simple example please

  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
  >
  >
  >
  >
  > Info: <http://www.boost.org>
  > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl>
  > Unsubscribe: <mailto:boost-users-unsubscribe_at_[hidden]>
  >
  >
  > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
  >
  >

        Yahoo! Groups Sponsor

  Info: <http://www.boost.org>
  Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl>
  Unsubscribe: <mailto:boost-users-unsubscribe_at_[hidden]>

  Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

[Non-text portions of this message have been removed]