31 Input/output library [input.output]

31.12 File systems [filesystems]

31.12.6 Class path [fs.class.path] Members [fs.path.member] Appends [fs.path.append]

The append operations use operator/= to denote their semantic effect of appending preferred-separator when needed.
path& operator/=(const path& p);
Effects: If p.is_absolute() || (p.has_root_name() && p.root_name() != root_name()), then operator=(p).
Otherwise, modifies *this as if by these steps:
  • If p.has_root_directory(), then removes any root directory and relative path from the generic format pathname.
    Otherwise, if !has_root_directory() && is_absolute() is true or if has_filename() is true, then appends path​::​preferred_separator to the generic format pathname.
  • Then appends the native format pathname of p, omitting any root-name from its generic format pathname, to the native format pathname.
[Example 1: 
Even if //host is interpreted as a root-name, both of the paths path("//host")/"foo" and path("//host/")/"foo" equal "//host/foo" (although the former might use backslash as the preferred separator).
Expression examples: // On POSIX, path("foo") /= path(""); // yields path("foo/") path("foo") /= path("/bar"); // yields path("/bar") // On Windows, path("foo") /= path(""); // yields path("foo\\") path("foo") /= path("/bar"); // yields path("/bar") path("foo") /= path("c:/bar"); // yields path("c:/bar") path("foo") /= path("c:"); // yields path("c:") path("c:") /= path(""); // yields path("c:") path("c:foo") /= path("/bar"); // yields path("c:/bar") path("c:foo") /= path("c:bar"); // yields path("c:foo\\bar")
— end example]
Returns: *this.
template<class Source> path& operator/=(const Source& source); template<class Source> path& append(const Source& source);
Effects: Equivalent to: return operator/=(path(source));
template<class InputIterator> path& append(InputIterator first, InputIterator last);
Effects: Equivalent to: return operator/=(path(first, last));