std::filesystem::directory_entry::exists
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.
Parameters
| ec | - | out-parameter for error reporting in the non-throwing overload |
Return value
true if the referred-to filesystem object exists.
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.
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
See also
|
(C++17)
|
checks whether path refers to existing file system object (function) |
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https://en.cppreference.com/w/cpp/filesystem/directory_entry/exists
