NAME¶

std::filesystem::directory_entry::last_write_time - std::filesystem::directory_entry::last_write_time

Synopsis¶

std::filesystem::file_time_type last_write_time() const; (1) (since C++17)
std::filesystem::file_time_type last_write_time( std::error_code& (2) (since C++17)
ec ) const noexcept;

If the last modification time is cached in this directory_entry, returns the cached
value. Otherwise, returns:

1) std::filesystem::last_write_time(path()).
2) std::filesystem::last_write_time(path(), ec).

Parameters¶

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

Return value¶

The last modification time for the referred-to filesystem object.

Exceptions¶

Any overload not marked noexcept may throw std::bad_alloc if memory allocation
fails.

1) Throws std::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.
2) 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.

Example¶

// Run this code

#include <chrono>
#include <ctime>
#include <filesystem>
#include <format>
#include <iostream>
#include <string>

std::string to_string(const std::filesystem::file_time_type& ftime)
{
#if __cpp_lib_format
return std::format("{:%c}", ftime);
#else
std::time_t cftime = std::chrono::system_clock::to_time_t(
std::chrono::file_clock::to_sys(ftime));
std::string str = std::asctime(std::localtime(&cftime));
str.pop_back(); // rm the trailing '\n' put by `asctime`
return str;
#endif
}

int main()
{
auto dir = std::filesystem::current_path();
using Entry = std::filesystem::directory_entry;
for (Entry const& entry : std::filesystem::directory_iterator(dir))
std::cout << to_string(entry.last_write_time()) << " : "
<< entry.path().filename() << '\n';
}

Possible output:¶

Wed Sep 6 13:37:13.960314156 2023 : "main.cpp"
Wed Sep 6 13:37:42.690271828 2023 : "a.out"

See also¶

last_write_time gets or sets the time of the last data modification
(C++17) (function)