• If the destination file does not exist,

• copies the contents and the attributes of the file to whichfrom resolves to the file to whichto resolves (symlinks are followed).

• Otherwise, if the destination file already exists:

• Ifto andfrom are the same as determined byequivalent(from, to), report an error.
• Otherwise, if none of the copy_file control options are set inoptions, report an error.
• Otherwise, ifcopy_options::skip_existing is set inoptions, do nothing.
• Otherwise, ifcopy_options::overwrite_existing is set inoptions, copy the contents and the attributes of the file to whichfrom resolves to the file to whichto resolves.
• Otherwise, ifcopy_options::update_existing is set inoptions, only copy the file iffrom is newer thanto, as defined bylast_write_time().

The non-throwing overloads returnfalse if an error occurs.

[edit]Parameters

[edit]Return value

true if the file was copied,false otherwise.

[edit]Exceptions

[edit]Notes

The functions involve at most one direct or indirect call tostatus(to) (used both to determine if the file exists, and, forcopy_options::update_existing option, its last write time).

Error is reported whencopy_file is used to copy a directory: usecopy for that.

copy_file follows symlinks: usecopy_symlink orcopy withcopy_options::copy_symlinks for that.

[edit]Example

#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");}

file1.txt holds : afile2.txt holds : aCould not copy sandbox/abc: copy_file: Is a directory: "sandbox/abc", "sandbox/def"

[edit]See also