[fs.path.itr]

# 31 Input/output library [[input.output]](./#input.output)

## 31.12 File systems [[filesystems]](filesystems#fs.path.itr)

### 31.12.6 Class path [[fs.class.path]](fs.class.path#fs.path.itr)

#### 31.12.6.6 Iterators [fs.path.itr]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15281)

Path iterators iterate over the elements of the pathname
in the [generic format](fs.path.generic "31.12.6.2 Generic pathname format [fs.path.generic]")[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15285)

A path​::​iterator is a constant iterator meeting all the
requirements of a [bidirectional iterator](bidirectional.iterators "24.3.5.6 Bidirectional iterators [bidirectional.iterators]") except that,
for dereferenceable iterators a and b of type path​::​iterator with a == b,
there is no requirement that *a and *b are bound to the same object[.](#2.sentence-1)

Its value_type is path[.](#2.sentence-2)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15296)

Calling any non-const member function of a path object
invalidates all iterators referring to elements of that object[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15300)

For the elements of the pathname in the generic format,
the forward traversal order is as follows:

- [(4.1)](#4.1)

  The [*root-name*](fs.path.generic#nt:root-name "31.12.6.2 Generic pathname format [fs.path.generic]") element, if present[.](#4.1.sentence-1)

- [(4.2)](#4.2)

  The [*root-directory*](fs.path.generic#nt:root-directory "31.12.6.2 Generic pathname format [fs.path.generic]") element, if present[.](#4.2.sentence-1)
  [*Note [1](#note-1)*:
  It is possible that the use of the generic format is needed
to ensure correct lexicographical comparison[.](#4.2.sentence-2)
 — *end note*]

- [(4.3)](#4.3)

  Each successive [*filename*](fs.path.generic#nt:filename "31.12.6.2 Generic pathname format [fs.path.generic]") element, if present[.](#4.3.sentence-1)

- [(4.4)](#4.4)

  An empty element, if a trailing non-root [*directory-separator*](fs.path.generic#nt:directory-separator "31.12.6.2 Generic pathname format [fs.path.generic]") is present[.](#4.4.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15315)

The backward traversal order is the reverse of forward traversal[.](#5.sentence-1)

[🔗](#lib:begin,path)

`iterator begin() const;
`

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15324)

*Returns*: An iterator for the first present element in the traversal
list above[.](#6.sentence-1)

If no elements are present, the end iterator[.](#6.sentence-2)

[🔗](#lib:end,path)

`iterator end() const;
`

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L15336)

*Returns*: The end iterator[.](#7.sentence-1)