30 Input/output library [input.output]

30.10 File systems [filesystems]

30.10.15 Filesystem operation functions [fs.op.funcs]

30.10.15.4 Copy file [fs.op.copy_file]

bool copy_file(const path& from, const path& to);
bool copy_file(const path& from, const path& to, error_code& ec) noexcept;

Returns: copy_file(from, to, copy_options::none) or
copy_file(from, to, copy_options::none, ec), respectively.

Throws: As specified in [fs.err.report].

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) noexcept;

Requires: At most one element from each option group ([fs.enum.copy.opts]) is set in options.

Effects: As follows:

(4.1)
Report a file already exists error as specified in [fs.err.report] if:
- (4.1.1)
  !is_regular_file(from), or
- (4.1.2)
  exists(to) and !is_regular_file(to), or
- (4.1.3)
  exists(to) and equivalent(from, to), or
- (4.1.4)
  exists(to) and
```
(options & (copy_options::skip_existing |
            copy_options::overwrite_existing |
            copy_options::update_existing)) == copy_options::none
```
(4.2)
Otherwise, copy the contents and attributes of the file from resolves to, to the file to resolves to, if:
- (4.2.1)
  !exists(to), or
- (4.2.2)
  (options & copy_options::overwrite_existing) != copy_options::none, or
- (4.2.3)
  (options & copy_options::update_existing) != copy_options::none and from is more recent than to, determined as if by use of the last_write_time function ([fs.op.last_write_time]).
(4.3)
Otherwise, no effects.

Returns: true if the from file was copied, otherwise false.

The signature with argument ec returns false if an error occurs.

Throws: As specified in [fs.err.report].

Complexity: At most one direct or indirect invocation of status(to).