std::experimental::filesystem::exists - cppreference.com (original) (raw)

Defined in header <experimental/filesystem>
bool exists( file_status s ) (1) (filesystem TS)
bool exists( const path& p ); bool exists( const path& p, error_code& ec ) (2) (filesystem TS)

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. The overload that does not take an 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 an 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

[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

#include #include <experimental/filesystem> #include #include namespace fs = std::experimental::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

| | determines file attributesdetermines file attributes, checking the symlink target (function) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | | represents file type and permissions (class) [edit] | | | cached status of the file designated by this directory entrycached symlink_status of the file designated by this directory entry (public member function of std::experimental::filesystem::directory_entry) [edit] |