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std::filesy...t_write_time(3) C++ Standard Libarystd::filesy...t_write_time(3)

NAME
       std::filesystem::directory_entry::last_write_time    -	 std::filesys-
       tem::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, re-
       turns 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 er-
       rors, 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_itera-
       tor(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)

http://cppreference.com		  2024.06.10	 std::filesy...t_write_time(3)

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