Reading in a binary file from offset into another file

Hi all,

I want to read the contents of a binary file from say offset 1E9AC to offset 2E9AC and everything read in gets saved as another binary file.

So it is basically creating a new binary file from part of another one. Im struggling a bit with how to do it though. Any ideas?

Thanks

1) read byte by byte until you've read 1E9AB characters. Continue reading and saving until you reach the 2E9ACth character. Output the buffer.

1a) read byte by byte until you've read 1E9AB characters. Continue reading and writing until you reach the 2E9ACth character.

2) read 10000 characters into a buffer. Read the next E9AB characters into the buffer. Then read in the next 10000 bytes. Output the buffer.

3) use one of the "seek()" file functions that places the file pointer at the requested byte. Then read in the next 10000 bytes. Output the buffer.

You could use the C++ method:

Code:

---

#include <fstream>
using namespace std;
...
ifstream in("InFilename", ios::in | ios::binary);
ifstream out("OutFilename", ios::out | ios::binary);
char ch;
if(!in)
{ //Failed to open file
 ...
 return 1;
}
in.seekg(NUMBER_OF_BYTES_TO_SKIP, ios::beg);
for(int i=0;i<NUMBER_OF_BYTES_TO_READ;i++)
{ if(in.get(ch))
    out << ch;
  else
    break;
}

---

Sorry if it is a bit thrown together. Hope it helps.

>>ifstream in("InFilename", ios::in | ios::binary);
>>ifstream out("OutFilename", ios::out | ios::binary);

wouldn't

ifstream in (""InFilename", ios::binary);
ofstream out(""OutFilename", ios::binary);

make more sense? Is there any particular reason to open
ifstream in ios::out - is that even legal?

Quote:

---

Originally Posted by Richie T

Is there any particular reason to open
ifstream in ios::out - is that even legal?

---

Actually I meant to use fstream - that would be it. Late at night :o

ios::in specifies that the file is capable of input
ios::out specifies that the file is capable of output

thanks for the help all :)