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# std::filesystem::equivalent

From cppreference.com
< cpp‎ | filesystem

Defined in header `<filesystem>` |  |
bool equivalent( const std::filesystem::path& p1, const std::filesystem::path& p2 ); bool equivalent( const std::filesystem::path& p1, const std::filesystem::path& p2, std::error_code& ec ); | (1) | (since C++17)

Checks whether the paths `p1` and `p2` refer to the same file or directory and have the same file status as determined by `status` (symlinks are followed).

If neither `p1` nor `p2` exists, or if both exist but neither is a file, directory, or symlink (as determined by `is_other`), an error is reported.

The non-throwing overload returns `false` on errors.

### [edit] Parameters

p1, p2 | - | paths to check for equivalence
ec | - | out-parameter for error reporting in the non-throwing overload

### [edit] Return value

true if the `p1` and `p2` refer to the same file or directory and their file status is the same. false otherwise.

### [edit] Exceptions

The overload that does not take a std::error_code& parameter throws filesystem_error on underlying OS API errors, constructed with `p1` as the first argument, `p2` as the second argument, and the OS error code as the error code argument. std::bad_alloc may be thrown if memory allocation fails. The overload taking a std::error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. This overload has
`noexcept` specification:
noexcept

### [edit] Notes

Two paths are considered to resolve to the same file system entity if `st_dev` and `st_ino` of their POSIX stat structure, obtained as if by POSIX stat, are equal. (meaning, the files are locate on the same device at the same location)

In particular, all hard links for the same file or directory are equivalent, and a symlink and its target on the same file system are equivalent.

### [edit] Example

Run this code

    #include <iostream>
    #include <cstdint>
    #include <filesystem>
    namespace fs = std::filesystem;
    int main()
    {
        // hard link equivalency
        fs::path p1 = ".";
        fs::path p2 = fs::current_path();
        if(fs::equivalent(p1, p2))
            std::cout << p1 << " is equivalent to " << p2 << '\n';

        // symlink equivalency
        fs::path p3 = "/lib/libc.so.6";
        fs::path p4 = p3.parent_path() / fs::read_symlink(p3);
        if(fs::equivalent(p3, p4))
            std::cout << p3 << " is equivalent to " << p4 << '\n';
    }

Possible output:

    "." is equivalent to "/var/tmp/test"
    "/lib/libc.so.6" is equivalent to "/lib/libc-2.12.so"

### [edit] See also

status symlink_status (C++17)(C++17) | determines file attributes determines file attributes, checking the symlink target (function) [edit]

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