std::experimental::filesystem::copy_file
From cppreference.com
< cpp | experimental | fs
| 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 ); bool copy_file( const path& from, const path& to, copy_options options, error_code& ec ); |
(2) | (filesystem TS) |
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 indicated 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_existingis set in options, do nothing. - Otherwise, if
copy_options::overwrite_existingis 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_existingis 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 overload |
Return value
true if the file was copied, false otherwise.
Exceptions
The overload that does not take aerror_code& parameter throws filesystem_error on underlying OS API errors, constructed with from as the first argument, 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 a 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
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.
Examples
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
| specifies semantics of copy operations (enum) | |
| copies a symbolic link (function) | |
| copies files or directories (function) |