std::filesystem::path::compare - cppreference.com (original) (raw)

Compares the lexical representations of the path and another path.

1. If root_name().native().compare(p.root_name().native()) is nonzero, returns that value.

Otherwise, if has_root_directory() != p.has_root_directory(), returns a value less than zero if has_root_directory() is false and a value greater than zero otherwise.

Otherwise returns a value less than, equal to or greater than ​0​ if the relative portion of the path (relative_path()) is respectively lexicographically less than, equal to or greater than the relative portion of p (p.relative_path()). Comparison is performed element-wise, as if by iterating both paths from begin() to end() and comparing the result of native() for each element.

1. Equivalent to compare(path(str)).

2. Equivalent to compare(path(s)).

Contents

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

[edit] Parameters

[edit] Return value

A value less than ​0​ if the path is lexicographically less than the given path.

A value equal to ​0​ if the path is lexicographically equal to the given path.

A value greater than ​0​ if the path is lexicographically greater than the given path.

[edit] Exceptions

2,3) May throw implementation-defined exceptions.

[edit] Notes

For two-way comparisons, binary operators may be more suitable.

[edit] Example

#include #include #include namespace fs = std::filesystem;   void demo(fs::path p1, fs::path p2, std::string_view msg) { std::cout << p1; const int rc = p1.compare(p2); if (rc < 0) std::cout << " < "; else if (rc > 0) std::cout << " > "; else std::cout << " == "; std::cout << p2 << " \t: " << msg << '\n'; }   int main() { demo("/a/b/", "/a/b/", "simple"); demo("/a/b/", "/a/b/c", "simple"); demo("/a/b/../b", "/a/b", "no canonical conversion"); demo("/a/b", "/a/b/.", "no canonical conversion"); demo("/a/b/", "a/c", "absolute paths order after relative ones"); }

Output:

"/a/b/" == "/a/b/"  : simple "/a/b/" < "/a/b/c" : simple "/a/b/../b" > "/a/b" : no canonical conversion "/a/b" < "/a/b/." : no canonical conversion "/a/b/" > "a/c"  : absolute paths order after relative ones

[edit] Defect reports

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

[edit] See also