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Guest
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 Posted: Thu Aug 24, 2006 9:10 am Post subject: how to copy a part of a binary file |
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I want to copy only a part of the binary file delimited by offset
values say START_OFFSET_ & END_OFFSET_ which can be as huge as a 50
Giga. Below is the program where I could set a START_OFFSET_ but could
not specify the END_OFFSET_ value.
Any thoughts? Please advise. Thanks.
#include <fstream>
#include <iostream>
#include <algorithm>
#include <ios>
#include <iterator>
#include <string>
#define START_OFFSET_ 5000000
#define END_OFFSET_ 10000000
using namespace std;
void main()
{
ifstream is("c:\\test.bin",ios_base::binary);
ofstream os("c:\\testparse.bin",ios_base::binary);
if (!is || !os)
{
cout<<"Could not open the file for read/write";
exit(1);
}
is.seekg(START_OFFSET_,ios::beg);
copy(istream_iterator<char> (is),
istream_iterator<char> (),
ostream_iterator<char> (os));
is.close();
os.close();
/* I wanted to have something like this
//basic_istream<char,char_traits<char> >& start =
is.seekg(START_OFFSET_,ios::beg);
//basic_istream<char,char_traits<char> >& end =
is.seekg(END_OFFSET_,ios::beg);
//copy( istream_iterator<char> (start),
// istream_iterator<char> (end),
// ostream_iterator<char> (os)); //Apparently, this does not work
*/
} |
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Jens Theisen
Guest
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| Posted: Thu Aug 24, 2006 9:10 am Post subject: Re: how to copy a part of a binary file |
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pedagani (AT) gmail (DOT) com wrote:
| Quote: | I want to copy only a part of the binary file delimited by offset
values say START_OFFSET_ & END_OFFSET_ which can be as huge as a 50
Giga. Below is the program where I could set a START_OFFSET_ but could
not specify the END_OFFSET_ value.
Any thoughts? Please advise. Thanks.
|
Try using the read and write functions of streams instead, they are also
much faster than using iterators that way.
Jens |
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Guest
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| Posted: Wed Sep 20, 2006 9:10 am Post subject: Re: how to copy a part of a binary file |
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Jerry Coffin wrote:
| Quote: | In article <1156397620.305575.142870 (AT) 75g2000cwc (DOT) googlegroups.com>,
pedagani (AT) gmail (DOT) com says...
I want to copy only a part of the binary file delimited by offset
values say START_OFFSET_ & END_OFFSET_ which can be as huge as a 50
Giga. Below is the program where I could set a START_OFFSET_ but could
not specify the END_OFFSET_ value.
Assuming (for the moment) that your implementation has something like
64-bit ints that have the range to directly address all possible file
sizes:
const std::ifstream::fpos start(START_OFFSET);
const std::ifstream::fpos stop(END_OFFSET+1);
std::copy(istream_iterator<char>(is),
isstream_iterator<char>(is)+ stop-start,
ostream_iterator<char>(os));
There are, however, a fair number of implementations that simply don't
have any standard type with a range as large as the file sizes they
support (and specifically less than the 50 gigabytes you mention). In a
case like this, there's probably no standard/portable code to do what
you want.
--
Later,
Jerry.
The universe is a figment of its own imagination.
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Thank you. Although it could not be directly applied for my
application, very insightful solution. |
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