cpp/filesystem/create directory

@1@ Creates the directory as if by POSIX  with a second argument of  (the parent directory must already exist). If the function fails because resolves to an existing directory, no error is reported. Otherwise on failure an error is reported. @2@ Same as, except that the attributes of the new directory are copied from (which must be a directory that exists). It is OS-dependent which attributes are copied: on POSIX systems, the attributes are copied as if by On Windows OS, no attributes of are copied. @3@ Executes for every element of  that does not already exist. If already exists, the function does nothing (this condition is not treated as an error).

Return value
if a directory was created for the directory resolves to,  otherwise.

Exceptions
@1,3@ @2@