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<H1>istream_iterator<T, Distance></H1>
<Table CellPadding=0 CellSpacing=0 width=100%>
<TR>
<TD Align=left><Img src = "iterators.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD>
<TD Align=right><Img src = "type.gif" Alt="" WIDTH = "194" HEIGHT = "39" ></TD>
</TR>
<TR>
<TD Align=left VAlign=top><b>Category</b>: iterators</TD>
<TD Align=right VAlign=top><b>Component type</b>: type</TD>
</TR>
</Table>
<h3>Description</h3>
An <tt>istream_iterator</tt> is an <A href="InputIterator.html">Input Iterator</A> that performs formatted
input of objects of type <tt>T</tt> from a particular <tt>istream</tt>. When end of
stream is reached, the <tt>istream_iterator</tt> takes on a special <i>end of
stream</i> value, which is a past-the-end iterator. Note that all of the
restrictions of an <A href="InputIterator.html">Input Iterator</A> must be obeyed, including the
restrictions on the ordering of <tt>operator*</tt> and <tt>operator++</tt>
operations.
<h3>Example</h3>
Fill a <tt><A href="Vector.html">vector</A></tt> with values read from standard input.
<pre>
<A href="Vector.html">vector</A><int> V;
<A href="copy.html">copy</A>(istream_iterator<int>(cin), istream_iterator<int>(),
<A href="back_insert_iterator.html">back_inserter</A>(V));
</pre>
<h3>Definition</h3>
Defined in <A href="iterator.h">iterator.h</A>.
<h3>Template parameters</h3>
<Table border>
<TR>
<TH>
Parameter
</TH>
<TH>
Description
</TH>
<TH>
Default
</TH>
</TR>
<TR>
<TD VAlign=top>
<tt>T</tt>
</TD>
<TD VAlign=top>
The <tt>istream_iterator</tt>'s value type. <tt>Operator*</tt> returns a <tt>const T&</tt>.
</TD>
<TD VAlign=top>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>Distance</tt>
</TD>
<TD VAlign=top>
The <tt>istream_iterator</tt>'s distance type.
</TD>
<TD VAlign=top>
<tt>ptrdiff_t</tt>
</TD>
</tr>
</table>
<h3>Model of</h3>
<A href="InputIterator.html">Input Iterator</A>
<h3>Type requirements</h3>
The value type <tt>T</tt> must be a type such that <tt>cin >> T</tt> is a
valid expression.
<P>
The value type <tt>T</tt> must be a model of <A href="DefaultConstructible.html">Default Constructible</A>.
<P>
The distance type must, as described in the
<A href="InputIterator.html">Input Iterator</A> requirements, be a signed integral type.
<h3>Public base classes</h3>
None.
<h3>Members</h3>
<Table border>
<TR>
<TH>
Member
</TH>
<TH>
Where defined
</TH>
<TH>
Description
</TH>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator()</tt>
</TD>
<TD VAlign=top>
<tt>istream_iterator</tt>
</TD>
<TD VAlign=top>
See below.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator(istream&)</tt>
</TD>
<TD VAlign=top>
<tt>istream_iterator</tt>
</TD>
<TD VAlign=top>
See below.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator(const istream_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="trivial.html">Trivial Iterator</A>
</TD>
<TD VAlign=top>
The copy constructor
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator& operator=(const istream_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="trivial.html">Trivial Iterator</A>
</TD>
<TD VAlign=top>
The assignment operator
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const T& operator*() const</tt>
</TD>
<TD VAlign=top>
<A href="InputIterator.html">Input Iterator</A>
</TD>
<TD VAlign=top>
Returns the next object in the stream.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator& operator++()</tt>
</TD>
<TD VAlign=top>
<A href="InputIterator.html">Input Iterator</A>
</TD>
<TD VAlign=top>
Preincrement.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator& operator++(int)</tt>
</TD>
<TD VAlign=top>
<A href="InputIterator.html">Input Iterator</A>
</TD>
<TD VAlign=top>
Postincrement.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>bool operator==(const istream_iterator&, const istream_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="trivial.html">Trivial iterator</A>
</TD>
<TD VAlign=top>
The equality operator. This is a global function, not a member function.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>input_iterator_tag iterator_category(const istream_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="iterator_tags.html">iterator tags</A>
</TD>
<TD VAlign=top>
Returns the iterator's category.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>T* value_type(const istream_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="iterator_tags.html">iterator tags</A>
</TD>
<TD VAlign=top>
Returns the iterator's value type.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>Distance* distance_type(const istream_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="iterator_tags.html">iterator tags</A>
</TD>
<TD VAlign=top>
Returns the iterator's distance type.
<
</TD>
</tr>
</table>
<h3>New members</h3>
These members are not defined
in the <A href="InputIterator.html">Input Iterator</A> requirements,
but are specific to <tt>istream_iterator</tt>.
<Table border>
<TR>
<TH>
Function
</TH>
<TH>
Description
</TH>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator()</tt>
</TD>
<TD VAlign=top>
The default constructor: Constructs an end-of-stream iterator.
This is a past-the-end iterator, and it is useful when constructing
a "range".
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>istream_iterator(istream& s)</tt>
</TD>
<TD VAlign=top>
Creates an <tt>istream_iterator</tt> that reads values from the input
stream <tt>s</tt>. When <tt>s</tt> reaches end of stream, this iterator will
compare equal to an end-of-stream iterator created using the
default constructor.
</TD>
</tr>
</table>
<h3>Notes</h3>
<h3>See also</h3>
<A href="ostream_iterator.html">ostream_iterator</A>, <A href="InputIterator.html" tppabs="http://www.sgi.com/Technology/STL/InputIterator.shtml">Input Iterator</A>, <A href="OutputIterator.html" tppabs="http://www.sgi.com/Technology/STL/OutputIterator.shtml">Output Iterator</A>.
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