parent_path() with or without trailing slash

Question

As explained in the documentation, the expected output of the following is:

boost::filesystem::path filePath1 = \"/home/user/\";
cout << filePath1.pare         


        

Answer 1

To remove the trailing separator from a path that is to a directory, so far this is working for me:

/**
 * Creates lexically normal (removes extra path separators and dots) directory
 * path without trailing path separator slash(es)
 * @param dir_path - directory path to normalize
 */
void normalize_dir_path(boost::filesystem::path& dir_path) {
    // @HACK - append non-existing file to path so that we may later resolve
    // normalized directory path using parent_path()
    dir_path /= "FILE.TXT";
    // Remove unneeded dots and slashes
    dir_path = dir_path.lexically_normal();
    // Remove trailing slash from original path!
    dir_path = dir_path.parent_path();
}

The above answer is similar to OP's original posted workaround (add '/') in combination with Wurmloch's comment about using lexically_normal(). One advantage is that only the documented methods from boost::filesystem are used. One possible disadvantage is that caller must be confident the input argument dir_path is intended to be a directory and not a regular file.

Using the normalize_dir_path(...) method to answer OP's question:

boost::filesystem::path filePath1 = "/home/user/";
normalize_dir_path(filePath1); // filePath1 is now "/home/user"
cout << filePath1.parent_path() << endl; // outputs "/home"

boost::filesystem::path filePath2 = "/home/user";
normalize_dir_path(filePath2); // filePath2 is now "/home/user"
cout << filePath2.parent_path() << endl; // outputs "/home"

boost::filesystem::path filePath3 = "/home/user/.";
normalize_dir_path(filePath3); // filePath3 is now "/home/user"
cout << filePath3.parent_path() << endl; // outputs "/home"

Update

Just realized that boost::filesystem::path::lexically_normal() is only available on BOOST version >= 1_60_0. For earlier versions, there appears to be a deprecated function available by default boost::filesystem::path::normalize() (as long as BOOST_FILESYSTEM_NO_DEPRECATED is not defined). So, my current normalize directory path method is along the lines:

#include 

void normalize_dir_path(boost::filesystem::path& dir_path) {
    // @HACK - append non-existing file to path so that we may later resolve
    // normalized directory path using parent_path()
    dir_path /= "FILE.TXT";
    // Remove unneeded dots and slashes
#if BOOST_VERSION >= 106000
    dir_path = dir_path.lexically_normal();
#else
    dir_path.normalize();
#endif
    // Remove trailing slash from original path!
    dir_path = dir_path.parent_path();
}