FreeBSD Manual Pages
std::filesystem::exists(3) C++ Standard Libary std::filesystem::exists(3) NAME std::filesystem::exists - std::filesystem::exists Synopsis Defined in header <filesystem> bool exists( std::filesystem::file_status s ) noexcept; (1) (since C++17) bool exists( const std::filesystem::path& p ); (2) (since C++17) bool exists( const std::filesystem::path& p, std::error_code& ec ) (3) (since C++17) noexcept; 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. 2,3) Let s be a std::filesystem::file_status determined as if by status(p) or status(p, ec) (symlinks are followed), respectively. Returns ex- ists(s). The non-throwing overload calls ec.clear() if status_known(s). Parameters s - file status to check p - path to examine ec - out-parameter for error reporting in the non-throwing overload Return value true if the given path or file status corresponds to an existing file or directory, false otherwise. Exceptions Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails. 2) Throws std::filesystem::filesystem_error on underlying OS API er- rors, constructed with p as the first path argument and the OS error code as the error code argument. 3) Sets a std::error_code& parameter to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. No filesystem exception is thrown if object does not exist (use re- turn value). Notes The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling exists(*it- erator) is less efficient than exists(iterator->status()). Example // Run this code #include <cstdint> #include <filesystem> #include <fstream> #include <iostream> namespace fs = std::filesystem; void demo_exists(const fs::path& p, fs::file_status s = fs::file_sta- tus{}) { 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() { const fs::path sandbox{"sandbox"}; fs::create_directory(sandbox); std::ofstream{sandbox/"file"}; // create regular file fs::create_symlink("non-existing", sandbox/"symlink"); demo_exists(sandbox); for (const auto& entry : fs::directory_iterator(sandbox)) demo_exists(entry, entry.status()); // use cached status from directory entry fs::remove_all(sandbox); } Output: "sandbox" exists "sandbox/symlink" does not exist "sandbox/file" exists See also status determines file attributes symlink_status determines file attributes, checking the symlink tar- get (C++17) (function) (C++17) file_status represents file type and permissions (C++17) (class) exists checks whether directory entry refers to existing file system object (public member function of std::filesystem::direc- tory_entry) http://cppreference.com 2024.06.10 std::filesystem::exists(3)
NAME | Synopsis | Parameters | Return value | Exceptions | Notes | Example | Output: | See also
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::filesystem::exists&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>