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std::filesystem::path::make_preferred(3) C++ Standard Libary std::filesystem::path::make_preferred(3)


std::filesystem::path::make_preferred - std::filesystem::path::make_preferred


path& make_preferred(); (since C++17)

Converts all directory separators in the generic-format view of the path to the
preferred directory separator.

For example, on Windows, where \ is the preferred separator, the path foo/bar will
be converted to foo\bar.



Return value



May throw implementation-defined exceptions.


Windows can use / as a separator, but prefers \, so make_preferred converts the
forward slashes to backslashes. On the other hand, POSIX does not use \ as a
separator, because backslashes are valid filename characters — the Windows path on
POSIX actually refers to a file with the name "a\\b\\c". For this reason the
"separators" are not converted.

// Run this code

#include <filesystem>
#include <iostream>
#include <iomanip>

int main()
std::filesystem::path windows_path{"a\\b\\c"};
std::filesystem::path posix_path{"a/b/c"};
std::cout << "Windows path: "
<< std::quoted(windows_path.string()) << " -> "
<< std::quoted(windows_path.make_preferred().string()) << '\n'
<< "POSIX path: "
<< std::quoted(posix_path.string()) << " -> "
<< std::quoted(posix_path.make_preferred().string()) << '\n';


# on Windows
Windows path: "a\\b\\c" -> "a\\b\\c"
POSIX path: "a/b/c" -> "a\\b\\c"
# on POSIX
Windows path: "a\\b\\c" -> "a\\b\\c"
POSIX path: "a/b/c" -> "a/b/c"

See also

alternative directory separator which may be used in addition
constexpr value_type to the portable /. On Windows, this is the backslash character
preferred_separator \. On POSIX, this is the same forward slash / as the portable
[static] separator
(public static member constant)