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<H1>insert_iterator<Container></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><Img src = "adaptors.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD>
<TD Align=right></TD>
</TR>
<TR>
<TD Align=left VAlign=top><b>Categories</b>: iterators, adaptors</TD>
<TD Align=right VAlign=top><b>Component type</b>: type</TD>
</TR>
</Table>
<h3>Description</h3>
<tt>Insert_iterator</tt> is an iterator adaptor that functions as an
<A href="OutputIterator.html">Output Iterator</A>: assignment through an <tt>insert_iterator</tt> inserts
an object into a <A href="Container.html">Container</A>. Specifically, if <tt>ii</tt> is an
<tt>insert_iterator</tt>, then <tt>ii</tt> keeps track of a <A href="Container.html">Container</A> <tt>c</tt>
and an insertion point <tt>p</tt>; the expression <tt>*ii = x</tt> performs
the insertion <tt>c.insert(p, x)</tt>. <A href="#1">[1]</A>
<P>
There are two different <A href="Container.html">Container</A> concepts that define this
expression: <A href="Sequence.html">Sequence</A>, and <A href="SortedAssociativeContainer.html" tppabs="http://www.sgi.com/Technology/STL/SortedAssociativeContainer.shtml">Sorted Associative Container</A>.
Both concepts define insertion into a container by means of
<tt>c.insert(p, x)</tt>, but the semantics of this expression is very
different in the two cases.
<P>
For a <A href="Sequence.html">Sequence</A> <tt>S</tt>, the expression <tt>S.insert(p, x)</tt> means to
insert the value <tt>x</tt> <i>immediately before</i> the iterator <tt>p</tt>. That
is, the two-argument version of <tt>insert</tt> allows you to control the
location at which the new element will be inserted. For a
<A href="SortedAssociativeContainer.html">Sorted Associative Container</A>, however, no such control is
possible: the elements in a <A href="SortedAssociativeContainer.html">Sorted Associative Container</A> always
appear in ascending order of keys. <A href="SortedAssociativeContainer.html">Sorted Associative Containers</A>
define the two-argument version of <tt>insert</tt> as an optimization. The
first argument is only a hint: it points to the location where the
search will begin.
<P>
If you assign through an <tt>insert_iterator</tt> several times, then you
will be inserting several elements into the underlying container. In
the case of a <A href="Sequence.html">Sequence</A>, they will appear at a particular location
in the underlying sequence, in the order in which they were inserted:
one of the arguments to <tt>insert_iterator</tt>'s constructor is an iterator
<tt>p</tt>, and the new range will be inserted immediately before <tt>p</tt>.
<P>
In the case of a <A href="SortedAssociativeContainer.html">Sorted Associative Container</A>, however, the
iterator in the <tt>insert_iterator</tt>'s constructor is almost irrelevant.
The new elements will not necessarily form a contiguous range; they
will appear in the appropriate location in the container, in ascending
order by key. The order in which they are inserted only affects
efficiency: inserting an already-sorted range into a
<A href="SortedAssociativeContainer.html">Sorted Associative Container</A> is an <i>O(N</i>) operation.
<h3>Example</h3>
Insert a range of elements into a <tt><A href="List.html">list</A></tt>.
<pre>
<A href="List.html">list</A><int> L;
L.push_front(3);
insert_iterator<<A href="List.html">list</A><int> > ii(L, L.begin());
*ii++ = 0;
*ii++ = 1;
*ii++ = 2;
<A href="copy.html">copy</A>(L.begin(), L.end(), <A href="ostream_iterator.html" tppabs="http://www.sgi.com/Technology/STL/ostream_iterator.shtml">ostream_iterator</A><int>(cout, " "));
// The values that are printed are 0 1 2 3.
</pre>
Merge two sorted lists, inserting the resulting range into a
<tt><A href="set.html">set</A></tt>. Note that a <tt><A href="set.html" tppabs="http://www.sgi.com/Technology/STL/set.shtml">set</A></tt> never contains duplicate
elements.
<pre>
int main()
{
const int N = 6;
int A1[N] = {1, 3, 5, 7, 9, 11};
int A2[N] = {1, 2, 3, 4, 5, 6};
<A href="set.html">set</A><int> result;
<A href="merge.html">merge</A>(A1, A1 + N, A2, A2 + N,
inserter(result, result.begin()));
<A href="copy.html">copy</A>(result.begin(), result.end(), <A href="ostream_iterator.html" tppabs="http://www.sgi.com/Technology/STL/ostream_iterator.shtml">ostream_iterator</A><int>(cout, " "));
cout << endl;
// The output is "1 2 3 4 5 6 7 9 11".
}
</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>Container</tt>
</TD>
<TD VAlign=top>
The type of Container into which values will be inserted.
</TD>
<TD VAlign=top>
</TD>
</tr>
</table>
<h3>Model of</h3>
<A href="OutputIterator.html">Output Iterator</A>. An insert iterator's set of value types (as
defined in the <A href="OutputIterator.html">Output Iterator</A> requirements) consists of
a single type: <tt><A href="Container.html">Container</A>::value_type</tt>.
<h3>Type requirements</h3>
<UL>
<LI>
The template parameter <tt>Container</tt> is a model of <A href="Container.html">Container</A>.
<LI>
<tt>Container</tt> is variable-sized, as described in the
<A href="Container.html">Container</A> requirements.
<LI>
<tt>Container</tt> has a two-argument <tt>insert</tt> member function.
Specifically, if <tt>c</tt> is an object of type <tt>Container</tt>,
<tt>p</tt> is an object of type <tt>Container::iterator</tt> and <tt>v</tt> is an
object of type <tt>Container::value_type</tt>, then <tt>c.insert(p, v)</tt>
must be a valid expression.
</UL>
<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>insert_iterator(Container&, Container::iterator)</tt>
</TD>
<TD VAlign=top>
<tt>insert_iterator</tt>
</TD>
<TD VAlign=top>
See below.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>insert_iterator(const insert_iterator&)</tt>
</TD>
<TD VAlign=top>
<A href="trivial.html">Trivial Iterator</A>
</TD>
<TD VAlign=top>
The copy constructor
</TD>
</TR>
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