Template:cpp/filesystem/time example

Run this code

#include <chrono>
#include <filesystem>
#include <format>
#include <fstream>
#include <iostream>

using namespace std::chrono_literals;

int main()
{
    auto p = std::filesystem::temp_directory_path() / "example.bin";
    std::ofstream{p.c_str()}.put('a'); // create file

    std::filesystem::file_time_type ftime = std::filesystem::last_write_time(p);
    std::cout << std::format("File write time is {}\n", ftime);

    // move file write time 1 hour to the future
    std::filesystem::last_write_time(p, ftime + 1h);

    // read back from the filesystem
    ftime = std::filesystem::last_write_time(p);
    std::cout << std::format("File write time is {}\n", ftime);

    std::filesystem::remove(p);
}

Possible output:

File write time is 2023-09-04 19:33:24.702639224
File write time is 2023-09-04 20:33:24.702639224