Joining filesystem paths in C

Question

Similar to how python has the convenient os.path.join() function, I was wondering if there was a good cross-platform way to do this in C.

My current approach is to set up some preprocessor directives with something like this

#ifdef defined(linux)
#define PATH_SEPARATOR "/"
#else
#define PATH_SEPARATOR "\\"
#endif

fwiw, I'm pretty sure all modern Windows OS support "/" path separators. — FatalError, Feb 10 '12 at 15:51
Hm, you could simply use `/` for everything, this should work for Windows and POSIX (although it might not on some other operating systems, so it depends on *how* portable your code has to be). — Niklas B., Feb 10 '12 at 15:52

score 4 · Accepted Answer · answered Feb 10 '12 at 15:59

I'm pretty sure many cross-platform libraries have such functionality. Maybe you want to have a look at APR's apr_filepath_merge function.

In C++, you could use Boost:

#include <boost/filesystem.hpp>
using namespace boost::filesystem;

[...]    

path path1("/tmp");
path path2("example");
path result = path1 / path2;

score 4 · Answer 2 · answered Feb 10 '12 at 16:01

4

There is no standard way to do this. Do it yourself or use a library. For example the Apache Portable Runtime provides apr_filepath_merge.

answered Feb 10 '12 at 16:01

score 1 · Answer 3 · answered Apr 11 '19 at 13:58

For C, you could use cwalk which is a little cross-platform library to do file path related things (either cwk_path_join or cwk_path_join_multiple):

#include <cwalk.h>
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
  char buffer[FILENAME_MAX];

  cwk_path_join("hello/there", "../world", buffer, sizeof(buffer));
  printf("The combined path is: %s", buffer);

  return EXIT_SUCCESS;
}

Outputs:

The combined path is: hello/world

Joining filesystem paths in C

3 Answers3