Concept OutputIterator

OutputIterator

Description

An output iterator is an iterator that can write a sequence of values. It is single-pass (old values of the iterator cannot be re-used), and write-only.

An output iterator represents a position in a (possibly infinite) sequence. Therefore, the iterator can point into the sequence (returning a value when dereferenced and being incrementable), or be off-the-end (and not dereferenceable or incrementable).

Associated types

value_type
```
std::iterator_traits<Iter>::value_type
```
The stated value type of the iterator (should be void for an output iterator that does not model some other iterator concept).
difference_type
```
std::iterator_traits<Iter>::difference_type
```
The difference type of the iterator

category

std::iterator_traits<Iter>::iterator_category

The category of the iterator

Notation

Iter: A type playing the role of iterator-type in the OutputIterator concept.
ValueType: A type playing the role of value-type in the OutputIterator concept.
i, j: Objects of type Iter
x: Object of type ValueType

Type expressions

: The type Iter must be a model of Assignable.
: The type ValueType must be a model of Assignable.
: The type Iter must be a model of DefaultConstructible.
: The type Iter must be a model of EqualityComparable.
Category tag: category must be derived from std::output_iterator_tag, a model of DefaultConstructible, and a model of CopyConstructible.
Difference type properties: difference_type must be a model of SignedInteger.

Valid expressions

Name	Expression	Type	Precondition	Semantics	Postcondition
Dereference	*i		`i` is incrementable (not off-the-end)
Dereference and assign	*i = x		`i` is incrementable (not off-the-end)		`*i` may not be written to again until it has been incremented.
Preincrement	++i	Iter &	`i` is incrementable (not off-the-end)
Postincrement	i++		`i` is incrementable (not off-the-end)	Equivalent to `(void)(++i)`	`i` is dereferenceable or off-the-end
Postincrement, dereference, and assign	*i++ = x		`i` is incrementable (not off-the-end)	Equivalent to `{*i = t; ++i;}`	`i` is dereferenceable or off-the-end

Complexity

All iterator operations must take amortized constant time.

Models

std::ostream_iterator, ...
std::insert_iterator, ...
std::front_insert_iterator, ...
std::back_insert_iterator, ...