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# std::filesystem::exists

From cppreference.com
< cpp‎ | filesystem

Defined in header `<filesystem>` |  |
bool exists( std::filesystem::file_status s ) | (1) | (since C++17)
bool exists( const std::filesystem::path& p ); bool exists( const std::filesystem::path& p, std::error_code& ec ) | (2) | (since C++17)

Checks if the given file status or path corresponds to an existing file or directory.

1) Equivalent to status_known(s) && s.type() != file_type::not_found.
2) Equivalent to exists(status(p)) or exists(status(p, ec)) (symlinks are followed). The non-throwing overload returns false if an error occurs.

### [edit] Parameters

s | - | file status to check
p | - | path to examine
ec | - | out-parameter for error reporting in the non-throwing overload

### [edit] Return value

true if the given path or file status corresponds to an existing file or directory, false otherwise.

### [edit] Exceptions

1)
`noexcept` specification:
noexcept
2) The overload that does not take a std::error_code& parameter throws filesystem_error on underlying OS API errors, constructed with `p` as the first 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

The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling `exists(*iterator)` is less efficient than `exists(iterator->status())`

### [edit] Example

Run this code

    #include <iostream>
    #include <fstream>
    #include <cstdint>
    #include <filesystem>
    namespace fs = std::filesystem;

    void demo_exists(const fs::path& p, fs::file_status s = fs::file_status{})
    {
        std::cout << p;
        if(fs::status_known(s) ? fs::exists(s) : fs::exists(p))
            std::cout << " exists\n";
        else
            std::cout << " does not exist\n";
    }
    int main()
    {
        fs::create_directory("sandbox");
        std::ofstream("sandbox/file"); // create regular file
        fs::create_symlink("non-existing", "sandbox/symlink");

        demo_exists("sandbox");
        for(auto it = fs::directory_iterator("sandbox"); it != fs::directory_iterator(); ++it)
            demo_exists(*it, it->status()); // use cached status from directory entry
        fs::remove_all("sandbox");
    }

Output:

    "sandbox" exists
    "sandbox/file" exists
    "sandbox/symlink" does not exist

### [edit] See also

status symlink_status (C++17)(C++17) | determines file attributes determines file attributes, checking the symlink target (function) [edit]
file_status (C++17) | represents file type and permissions (class) [edit]
status symlink_status | status of the file designated by this directory entry symlink_status of the file designated by this directory entry (public member function of `std::filesystem::directory_entry`) [edit]

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