istream_iterator<T, Distance>

Category: iterators Component type: type


An istream_iterator is an Input Iterator that performs formatted input of objects of type T from a particular istream. When end of stream is reached, the istream_iterator takes on a special end of stream value, which is a past-the-end iterator. Note that all of the restrictions of an Input Iterator must be obeyed, including the restrictions on the ordering of operator* and operator++ operations.


Fill a vector with values read from standard input.
vector<int> V;
copy(istream_iterator<int>(cin), istream_iterator<int>(),


Defined in the standard header iterator, and in the nonstandard backward-compatibility header iterator.h.

Template parameters

Parameter Description Default
T The istream_iterator's value type. Operator* returns a const T&.  
Distance The istream_iterator's distance type. ptrdiff_t

Model of

Input Iterator

Type requirements

The value type T must be a type such that cin >> T is a valid expression.

The value type T must be a model of Default Constructible.

The distance type must, as described in the Input Iterator requirements, be a signed integral type.

Public base classes



Member Where defined Description
istream_iterator() istream_iterator See below.
istream_iterator(istream&) istream_iterator See below.
istream_iterator(const istream_iterator&) Trivial Iterator The copy constructor
istream_iterator& operator=(const istream_iterator&) Trivial Iterator The assignment operator
const T& operator*() const Input Iterator Returns the next object in the stream.
istream_iterator& operator++() Input Iterator Preincrement.
istream_iterator& operator++(int) Input Iterator Postincrement.
bool operator==(const istream_iterator&, const istream_iterator&) Trivial iterator The equality operator. This is a global function, not a member function.
input_iterator_tag iterator_category(const istream_iterator&) iterator tags Returns the iterator's category.
T* value_type(const istream_iterator&) iterator tags Returns the iterator's value type.
Distance* distance_type(const istream_iterator&) iterator tags Returns the iterator's distance type. <

New members

These members are not defined in the Input Iterator requirements, but are specific to istream_iterator.
Function Description
istream_iterator() The default constructor: Constructs an end-of-stream iterator. This is a past-the-end iterator, and it is useful when constructing a "range".
istream_iterator(istream& s) Creates an istream_iterator that reads values from the input stream s. When s reaches end of stream, this iterator will compare equal to an end-of-stream iterator created using the default constructor.


See also

ostream_iterator, Input Iterator, Output Iterator.
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