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std::experi..._write_time(3)   C++ Standard Libary  std::experi..._write_time(3)

NAME
     std::experimental::filesystem::last_write_time	  -	 std::experimen-
     tal::filesystem::last_write_time

Synopsis
	Defined in header <experimental/filesystem>
	file_time_type last_write_time( const  path&  p  );		     (1)
     (filesystem TS)
	file_time_type last_write_time( const path& p, error_code& ec )
	void last_write_time( const path& p, file_time_type new_time );
	void  last_write_time(	const  path&  p, file_time_type new_time,    (2)
     (filesystem TS)
	error_code& ec );

	1) Returns the time of the last modification of p, determined as  if  by
     accessing the
	member	st_mtime  of  the  POSIX  stat (symlinks are followed). The non-
     throwing overload
	returns file_time_type::min() on errors.
	2) Changes the time of the last modification of p, as if by POSIX  futi-
     mens (symlinks
	are followed).

Parameters
	p	 - path to examine or modify
	new_time - new modification time
	ec	  -  out-parameter for error reporting in the non-throwing over-
     load

Return value
	1) The time of the last modification of p.
	2) (none)

Exceptions
	The overload that does not take an error_code& parameter throws filesys-
     tem_error on
	underlying OS API errors, constructed with p as the first  argument  and
     the OS error
	code  as the error code argument. std::bad_alloc may be thrown if memory
     allocation
	fails. The overload taking an 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.
     This overload
	has
	noexcept specification:
	noexcept

Notes
	It is not guaranteed that immediately after setting the write time,  the
     value
	returned  by  (1)  is the same as what was passed as the argument to (2)
     because the
	file system's time may be more granular than file_time_type.

Example
     // Run this code

      #include <chrono>
      #include <experimental/filesystem>
      #include <fstream>
      #include <iomanip>
      #include <iostream>
      namespace fs = std::experimental::filesystem;
      using namespace std::chrono_literals;

      int main()
      {
	  fs::path p = fs::current_path() / "example.bin";
	  std::ofstream(p.c_str()).put('a'); // create file
	  auto ftime = fs::last_write_time(p);

	  std::time_t cftime = decltype(ftime)::clock::to_time_t(ftime); //  as-
     suming system_clock
	  std::cout << "File write time is " << std::asctime(std::localtime(&cf-
     time)) << '\n';

	  fs::last_write_time(p,  ftime + 1h); // move file write time 1 hour to
     the future
	  ftime = fs::last_write_time(p); // read back from the filesystem

	  cftime = decltype(ftime)::clock::to_time_t(ftime);
	  std::cout << "File write time is " << std::asctime(std::localtime(&cf-
     time)) << '\n';
	  fs::remove(p);
      }

Possible output:
      File write time is Tue Mar 31 19:47:04 2015

      File write time is Tue Mar 31 20:47:04 2015

See also
	file_time_type represents file time values
		       (typedef)

Categories:
	  * Noindexed pages
	  * unconditionally noexcept

Hidden categories:
	  * Pages with unreviewed unconditional noexcept template
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http://cppreference.com 	   2024.06.10	    std::experi..._write_time(3)
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