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std::filesystem::directory_entry::exists

From cppreference.com
 
 
 
 
bool exists() const;
bool exists( std::error_code& ec ) const noexcept;
(since C++17)

Checks whether the pointed-to object exists. Effectively returns std::filesystem::exists(status()) or std::filesystem::exists(status(ec)), respectively

Contents

[edit] Parameters

ec - out-parameter for error reporting in the non-throwing overload

[edit] Return value

true if the referred-to filesystem object exists.

[edit] Exceptions

The overload that does not take a std::error_code& parameter throws filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument. 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. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

[edit] Example

#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>
 
namespace fs = std::filesystem;
 
int main()
{
    // store current path to restore it at exit
    const auto old_current_path = fs::current_path();
 
    // create "sanbox" directory in temp dir
    const auto dir_sandbox = fs::temp_directory_path() / "sandbox";
 
    if (!fs::create_directory(dir_sandbox)) {
        std::cout << "ERROR #1" << '\n';
        return -1;
    }
 
    fs::current_path(dir_sandbox); // switch to newly created dir
 
    fs::directory_entry entry_sandbox { dir_sandbox };
    if (!entry_sandbox.exists()) {
        std::cout << "ERROR #2" << '\n';
        return -1;
    }
 
    std::cout << "Current dir: " << entry_sandbox.path().filename() << '\n';
 
    fs::path path_tmp_file = dir_sandbox / "tmp_file";
 
    std::ofstream file( path_tmp_file.string() ); // create regular file
    file << "cppreference.com"; // write 16 bytes
    file.flush();
 
    fs::directory_entry entry_tmp_file{ path_tmp_file };
 
    if (entry_tmp_file.exists()) {
        std::cout << "File " << entry_tmp_file.path().filename()
                  << " has size: " << entry_tmp_file.file_size() << '\n';
    } else {
        std::cout << "ERROR #3" << '\n';
    }
 
    // cleanup
    fs::current_path(old_current_path);
    fs::remove_all(dir_sandbox);
}

Possible output:

Current dir: "sandbox"
File "tmp_file" has size: 16

[edit] See also

(C++17)
checks whether path refers to existing file system object
(function) [edit]