Книга: Standard Template Library Programmer
ostream_iterator
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ostream_iterator<T>
Category: iterators
Component type: type
Description
An ostream_iterator is an Output Iterator that performs formatted output of objects of type T to a particular ostream. Note that all of the restrictions of an Output Iterator must be obeyed, including the restrictions on the ordering of operator* and operator++ operations.
Example
Copy the elements of a vector to the standard output, one per line.
vector<int> V;
// …
copy(V.begin(), V.end(), ostream_iterator<int>(cout, "n"));
Definition
Defined in the standard header iterator, and in the nonstandard backward-compatibility header iterator.h.
Template parameters
| Parameter | Description |
|---|---|
T |
The type of object that will be written to the ostream. The set of value types of an ostream_iterator consists of a single type, T. |
Model of
Output Iterator.
Type requirements
T must be a type such that cout << T is a valid expression.
Public base classes
None.
Members
| Member | Where defined | Description |
|---|---|---|
ostream_iterator(ostream&) |
ostream_iterator |
See below. |
ostream_iterator(ostream&, const char* s) |
ostream_iterator |
See below. |
ostream_iterator(const ostream_iterator&) |
Output Iterator | The copy constructor |
ostream_iterator& operator=(const ostream_iterator&) |
Output Iterator | The assignment operator |
ostream_iterator& operator=(const T&) |
Output Iterator | Used to implement the Output Iterator requirement *i = t. [1] |
ostream_iterator& operator*() |
Output Iterator | Used to implement the Output Iterator requirement *i = t. [1] |
ostream_iterator& operator++() |
Output Iterator | Preincrement |
ostream_iterator& operator++(int) |
Output Iterator | Postincrement |
output_iterator_tag iterator_category(const ostream_iterator&) |
iterator tags | Returns the iterator's category. |
New members
These members are not defined in the Output Iterator requirements, but are specific to ostream_iterator.
| Function | Description |
|---|---|
| ostream_iterator(ostream& s) | Creates an ostream_iterator such that assignment of t through it is equivalent to s << t. |
| ostream_iterator(ostream& s, const char* delim) | Creates an ostream_iterator such that assignment of t through it is equivalent to s << t << delim. |
Notes
[1] Note how assignment through an ostream_iterator is implemented. In general, unary operator* must be defined so that it returns a proxy object, where the proxy object defines operator= to perform the output operation. In this case, for the sake of simplicity, the proxy object is the ostream_iterator itself. That is, *i simply returns i , and *i = t is equivalent to i = t. You should not, however, rely on this behavior. It is an implementation detail, and it is not guaranteed to remain the same in future versions.
See also
istream_iterator, Output Iterator, Input Iterator.
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