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Category: iterators Component type: type


Output_iterator is an iterator base class: it is intended that an iterator that is a model of OutputIterator may be defined by inheriting from output_iterator [1]. Output_iterator is entirely empty: it has no member functions, member variables, or nested types. It exists solely to simplify the definition of the functions iterator_category, distance_type, and value_type.


class my_output_iterator : public output_iterator

This declares my_output_iterator to be an OutputIterator. If Iter is an object of class my_output_iterator, then iterator_category(Iter) will return output_iterator_tag(), and distance_type and value_type will be undefined for objects of class my_output_iterator.


Defined in the standard header iterator, and in the nonstandard backward-compatibility header iterator.h. This class is no longer part of the C++ standard, although it was present in early drafts of the standard. It is retained in this implementation for backward compatibility.

Template parameters

None. (Note that OutputIterator need have neither distance types nor value types.)

Model of


Public base classes


Type requirements


Public base classes




New Members



[1] It is not required that an OutputIterator inherit from the base output_iterator. It is, however, required that the function iterator_category be defined for every OutputIterator. (Or, if you are using the iterator_traits mechanism, that iterator_traits is properly specialized for every OutputIterator.) Since it is defined for the base output_iterator, the easiest way to ensure that it defined for a new type is to derive that class from output_iterator and rely on the derived-to-base standard conversion of function arguments.

See also

The iterator_tags overview, iterator_traits, iterator_category, value_type, distance_type, input_iterator, forward_iterator, bidirectional_iterator, random_access_iterator

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