Read/Write/Performance

Hello
I want to read in a file binary (manipulate it) and write it back to a file. In other words I would like to copy a file.

Code:

        ifstream in("file1.dat",ios::binary);
        ofstream out("file2.dat",ofstream::binary);
         
        in.seekg(0, ios::end);
        unsigned long file_size = in.tellg();
        in.seekg(0, ios::beg);                        

        char *buffer;
        buffer = new char [file_size];
        in.read(buffer,file_size);
        out.write(buffer,file_size);

I thought this code should do it but I tried to copy a 1.11KB big file and the result file was just 1KB. Why? And is this an efficient way to read and write or is there a quicker possibility?

Later I need to read the file bytewise so I would do it with

Code:

in.read(buffer,1);
out.write(buffer,1);

is this fast or is in.get() faster...?

Thanks in advance.
slapy

Probably the fastest way to copy a file in C++ is:

Code:

out<< in.rdbuf();

Also you have this:
> ofstream out("file2.dat",ofstream::binary);
Which should be:
ofstream out("file2.dat",ios::binary);

That's probably why it only copied 1KB vs 1.11KB.