On Tuesday, June 10, 2003, at 9:08 AM, Vladimir Prus wrote:
[SNIP]
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?
I'll consider it.
[A few hours pass...]
How about something like this:
//================================================================
#include <cstdlib>
#include <exception>
#include <fstream>
#include <ios>
#include <iostream>
#include <ostream>
#include
#ifndef BLOCK_SIZE
#define BLOCK_SIZE 1024
#endif
int
main
(
int argc,
char const * argv[]
)
try
{
boost::crc_32_type result;
// Loop over each file argument
for ( int i = 1 ; i < argc ; ++i )
{
std::ifstream ifs( argv[i], std::ios_base::binary );
if ( ifs/*std::ifstream ifs(argv[i],
std::ios_base::binary)*/ )
{
/*char buffer[ BLOCK_SIZE ];
std::streamsize len;
while ( 0 < (len = ifs.readsome( buffer, BLOCK_SIZE )) )
{
result.process_bytes( buffer, len );
}*/
char c;
while ( ifs.get(c) )
{
result.process_byte( c );
}
}
else
{
std::cerr << "Failed to open file '" << argv[i]
<< "'." << std::endl;
}
}
std::cout << std::hex << result.checksum() << std::endl;
return EXIT_SUCCESS;
}
catch ( std::exception &e )
{
std::cerr << "Found an exception with '" << e.what()
<< "'." << std::endl;
return EXIT_FAILURE;
}
catch ( ... )
{
std::cerr << "Found an unknown exception." << std::endl;
return EXIT_FAILURE;
}
//================================================================
Note in the "if" statement, I had the construction in it. However,
neither one of my compilers took it! Moving the constructor call
worked, but I thought my original method should be accepted.
One compiler finished after the above 'fix'. The other (a variant of
GCC 3.1) complained about missing symbols at link-time; it could not
create the global objects hidden in Boost.CRC. (I haven't worked on
the code in a long time; there could be quirks on compilers written
after Boost.CRC.)
When I ran the program under the compiler that worked, the "readsome"
function always returned zero! There were no suitable substitutes; the
"read" function doesn't tell you how many characters it read (bad if
the last block isn't full) and the multi-character "get" functions use
delimiters. So this program is stuck at single-character reads at the
moment. Maybe I should switch to the stream-buffer method you used.
Can you try this out to make sure the problems aren't just mine?
Daryle
