Книга: Standard Template Library Programmer
Iterator classes
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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. |
See also
ostream_iterator, Input Iterator, Output Iterator.
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