std::filesystem::path::lexically_normal, std::filesystem::path::lexically_relative, std::filesystem::path::lexically_proximate - cppreference.com (original) (raw)

1. Returns *this converted to normal form in its generic format.

2. Returns *this made relative to base.

• First, if root_name() != base.root_name() is true or is_absolute() != base.is_absolute() is true or (!has_root_directory() && base.has_root_directory()) is true or any filename in relative_path() or base.relative_path() can be interpreted as a root-name, returns a default-constructed path.

• Otherwise, first determines the first mismatched element of *this and base as if by auto [a, b] = mismatch(begin(), end(), base.begin(), base.end()), then

• if a == end() and b == base.end(), returns path("."),

• otherwise, define N as the number of nonempty filename elements that are neither dot nor dot-dot in [b, base.end()), minus the number of dot-dot filename elements, If N < 0, returns a default-constructed path,

• otherwise, if N = 0 and a == end() || a->empty(), returns path("."),

• otherwise returns an object composed from

• a default-constructed path() followed by

• N applications of operator/=(path("..")), followed by

• one application of operator/= for each element in the half-open range [a, end()).

1. If the value of lexically_relative(base) is not an empty path, return it. Otherwise return *this.

Contents

• 1 Parameters
• 2 Return value
• 3 Exceptions
• 4 Notes
• 5 Example
• 6 Defect reports
• 7 See also

[edit] Parameters

(none)

[edit] Return value

1. The normal form of the path.

2. The relative form of the path.

3. The proximate form of the path.

[edit] Exceptions

May throw implementation-defined exceptions.

[edit] Notes

These conversions are purely lexical. They do not check that the paths exist, do not follow symlinks, and do not access the filesystem at all. For symlink-following counterparts of lexically_relative and lexically_proximate, see relative and proximate.

On Windows, the returned path has backslashes (the preferred separators).

On POSIX, no filename in a relative path is acceptable as a root-name.

[edit] Example

#include #include #include namespace fs = std::filesystem;   int main() { assert(fs::path("a/./b/..").lexically_normal() == "a/"); assert(fs::path("a/.///b/../").lexically_normal() == "a/"); assert(fs::path("/a/d").lexically_relative("/a/b/c") == "../../d"); assert(fs::path("/a/b/c").lexically_relative("/a/d") == "../b/c"); assert(fs::path("a/b/c").lexically_relative("a") == "b/c"); assert(fs::path("a/b/c").lexically_relative("a/b/c/x/y") == "../.."); assert(fs::path("a/b/c").lexically_relative("a/b/c") == "."); assert(fs::path("a/b").lexically_relative("c/d") == "../../a/b"); assert(fs::path("a/b").lexically_relative("/a/b") == ""); assert(fs::path("a/b").lexically_proximate("/a/b") == "a/b"); }

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also