std::experimental::filesystem:: 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 options , 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

Return value

true if the file was copied, false otherwise.

Exceptions

Notes

The functions involve at most one direct or indirect call to status(to) (used both to determine if the file exists, and, for copy_options::update_existing 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

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

See also