Copy a file in a sane, safe and efficient way

Question

I search for a good way to copy a file (binary or text). I\'ve written several samples, everyone works. But I want hear the opinion of seasoned programmers.

I missin

Answer 1

Too many!

The "ANSI C" way buffer is redundant, since a FILE is already buffered. (The size of this internal buffer is what BUFSIZ actually defines.)

The "OWN-BUFFER-C++-WAY" will be slow as it goes through fstream, which does a lot of virtual dispatching, and again maintains internal buffers or each stream object. (The "COPY-ALGORITHM-C++-WAY" does not suffer this, as the streambuf_iterator class bypasses the stream layer.)

I prefer the "COPY-ALGORITHM-C++-WAY", but without constructing an fstream, just create bare std::filebuf instances when no actual formatting is needed.

For raw performance, you can't beat POSIX file descriptors. It's ugly but portable and fast on any platform.

The Linux way appears to be incredibly fast — perhaps the OS let the function return before I/O was finished? In any case, that's not portable enough for many applications.

EDIT: Ah, "native Linux" may be improving performance by interleaving reads and writes with asynchronous I/O. Letting commands pile up can help the disk driver decide when is best to seek. You might try Boost Asio or pthreads for comparison. As for "can't beat POSIX file descriptors"… well that's true if you're doing anything with the data, not just blindly copying.