How can I copy files in C without platform dependency?

Question

It looks like this question is pretty simple but I can't find the clear solution for copying files in C without platform dependency.

I used a system() call in my open source project for creating a directory, copying files and run external programs. It works very well in Mac OS X and other Unix-ish systems, but it fails on Windows. The problem was:

system( "cp a.txt destination/b.txt" );

• Windows uses backslashes for path separator. (vs slashes in Unix-ish)
• Windows uses 'copy' for the internal copy command. (vs cp in Unix-ish)

How can I write a copying code without dependency?

( Actually, I wrote macros to solve this problems, but it's not cool. http://code.google.com/p/npk/source/browse/trunk/npk/cli/tests/testutil.h, L22-56 )

Answer 1

The system() function is a lot more trouble than it's worth; it invokes the shell in a seperate proccess, and should usually be avoided.

Instead fopen() a.txt and dest/b.text, and use getc()/putc() to do the copying (because the standard library is more likely to do page-aligned buffering than you)

FILE *src = fopen("a.txt", "rb");
FILE *dst = fopen("dest/b.txt", "wb");
int i;
for (i = getc(src); i != EOF; i = getc(src))
{
    putc(i, dst);
}
fclose(dst);
fclose(src);