C++Talk.NET

Paolo · Guest

Hi all!

I'm using ofstream and seekp to write a file. The problem is I have to
write a very big file, more than 4 Gb, but the streamoff that I have to
pass to seekp isn't a 64 bit int (it's a long int) so I can't use it!
Is it normal or there is some workaround for this?

Thank you

Paolo · Guest

I'm going to explain better:

I have to write a big file to disk. I used ofstream and something like

int dim = 1024 * 1024;
ch = new char[dim];
os.write(ch,dim);

Then I had to use seekp to find the position of a certain buffer,
because I receive packets with the buffer to write, the lenght of the
buffer and the offset from the beginning of the file.
The problem is that the file could be bigger than 4 Gb, so when I use
seekp I get an error, or better it doesnt work. For example

long long int big = (long long int)5 * 1024 * 1024 * 1024;
os.seekp(big,ios_base::beg);
cout << os.tellp();

The output of this piece of code is -1!!!!!

Is there a way to use seekp with 64 bit integers?
If not, I think I'll have to try to use os.open(filename,
ios_base::ate) (it gets me to the end of file rigth??), but first I
wanted to try seekp, because I wouldn't have to save a non aligned
packet in memory...

Thank you for your help!

Paolo