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Standard Template Library Programmer's Guide
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istream_iterator<T, Distance>


Category: iterators	Component type: type

Description

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.

Example

Fill a vector with values read from standard input.

vector<int> V;
copy(istream_iterator<int>(cin), istream_iterator<int>(),
     back_inserter(V));

Definition

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

None.

Members

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.