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

NAME
       std::experimental::filesystem::copy_file	 - std::experimental::filesys-
       tem::copy_file

Synopsis
	  Defined in header <experimental/filesystem>
	  bool copy_file( const	path& from, const path&	to );
	  bool copy_file( const	path& from, const path&	to, error_code&	ec (1)
       (filesystem TS)
	  );
	  bool copy_file( const	path& from, const path&	to, copy_options
	  options );							   (2)
       (filesystem TS)
	  bool copy_file( const	path& from, const path&	to, copy_options
	  options, error_code& ec );

	  1) The default, equivalent to	(2) with  copy_options::none  used  as
       options.
	  2)  Copies a single file from	from to	to, using the copy options in-
       dicated by
	  options. The behavior	is undefined if	there is more than one	option
       in any of the
	  copy_options option group present in options (even in	the groups not
       relevant	to
	  copy_file).
	    * If the destination file does not exist,

	    * copies the contents and the attributes of	the file to which from
       resolves	to the
	      file to which to resolves	(symlinks are followed).
	    * Otherwise, if the	destination file already exists:

	    *  If  to  and from	are the	same as	determined by equivalent(from,
       to), report an
	      error.
	    * Otherwise, if none of the	copy_file control options are  set  in
       options,	report
	      an error.
	    *  Otherwise, if copy_options::skip_existing is set	in options, do
       nothing.
	    * Otherwise, if copy_options::overwrite_existing  is  set  in  op-
       tions, copy the
	      contents	and  the attributes of the file	to which from resolves
       to the file to
	      which to resolves.
	    * Otherwise, if copy_options::update_existing is set  in  options,
       only copy the
	      file if from is newer than to, as	defined	by last_write_time().

	  The non-throwing overloads return false if an	error occurs.

Parameters
	  from - path to the source file
	  to   - path to the target file
	  ec	-  out-parameter for error reporting in	the non-throwing over-
       load

Return value
	  true if the file was copied, false otherwise.

Exceptions
	  The overload that does not  take  an	error_code&  parameter	throws
       filesystem_error	on
	  underlying  OS  API errors, constructed with from as the first argu-
       ment, to	as the
	  second 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 er-
       ror_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
	  The functions	involve	at most	one direct or indirect	call  to  sta-
       tus(to) (used both
	  to  determine	 if the	file exists, and, for copy_options::update_ex-
       isting option, its
	  last write time).

	  Error	is reported when copy_file is used to copy  a  directory:  use
       copy for	that.

	  copy_file follows symlinks: use copy_symlink or copy with
	  copy_options::copy_symlinks for that.

Example
       // Run this code

	#include <experimental/filesystem>
	#include <fstream>
	#include <iostream>
	namespace fs = std::experimental::filesystem;

	int main()
	{
	    fs::create_directory("sandbox");
	    std::ofstream("sandbox/file1.txt").put('a');

	    fs::copy_file("sandbox/file1.txt", "sandbox/file2.txt");

	    // now there are two files in sandbox:
	    std::cout << "file1.txt holds : "
		      << std::ifstream("sandbox/file1.txt").rdbuf() << '\n';
	    std::cout << "file2.txt holds : "
		      << std::ifstream("sandbox/file2.txt").rdbuf() << '\n';

	    // fail to copy directory
	    fs::create_directory("sandbox/abc");
	    try
	    {
		fs::copy_file("sandbox/abc", "sandbox/def");
	    }
	    catch (fs::filesystem_error& e)
	    {
		std::cout  <<  "Could  not  copy sandbox/abc: "	<< e.what() <<
       '\n';
	    }
	    fs::remove_all("sandbox");
	}

Possible output:
	file1.txt holds	: a
	file2.txt holds	: a
	Could not copy sandbox/abc: copy_file: Is a directory:	"sandbox/abc",
       "sandbox/def"

See also
	  copy_options specifies semantics of copy operations
		       (enum)
	  copy_symlink copies a	symbolic link
		       (function)
	  copy	       copies files or directories
		       (function)

Categories:
	    * Noindexed	pages
	    * unconditionally noexcept

Hidden categories:
	    * Pages with unreviewed unconditional noexcept template
	    * Pages with unreviewed noexcept template

http://cppreference.com		  2024.06.10	  std::experi...::copy_file(3)

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