Книга: Standard Template Library Programmer

output_iterator

output_iterator

Category: iterators

Component type: type

Output_iterator is an iterator base class: it is intended that an iterator that is a model of Output Iterator 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 Output Iterator. 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.

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

Assignable

None

None.

None.

None.

None.

[1] It is not required that an Output Iterator inherit from the base output_iterator. It is, however, required that the function iterator_category be defined for every Output Iterator. (Or, if you are using the iterator_traits mechanism, that iterator_traits is properly specialized for every Output Iterator.) 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.

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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