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<BR Clear>
<H1>map<Key, Data, Compare, Alloc></H1>
<Table CellPadding=0 CellSpacing=0 width=100%>
<TR>
<TD Align=left><Img src = "containers.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>: containers</TD>
<TD Align=right VAlign=top><b>Component type</b>: type</TD>
</TR>
</Table>
<h3>Description</h3>
<tt>Map</tt> is a <A href="SortedAssociativeContainer.html">Sorted Associative Container</A> that associates objects of
type <tt>Key</tt> with objects of type <tt>Data</tt>. <tt>Map</tt> is a
<A href="PairAssociativeContainer.html">Pair Associative Container</A>, meaning that its value type is
<tt><A href="pair.html">pair</A><const Key, Data></tt>. It is also a
<A href="UniqueAssociativeContainer.html">Unique Associative Container</A>, meaning that no two elements have
the same key.
<P>
<tt>Map</tt> has the important property that inserting a new element
into a <tt>map</tt> does not invalidate iterators that point to existing
elements. Erasing an element from a set also does not invalidate
any iterators, except, of course, for iterators that actually point
to the element that is being erased.
<h3>Example</h3>
<pre>
struct ltstr
{
bool operator()(const char* s1, const char* s2) const
{
return strcmp(s1, s2) < 0;
}
};
int main()
{
map<const char*, int, ltstr> months;
months["january"] = 31;
months["february"] = 28;
months["march"] = 31;
months["april"] = 30;
months["may"] = 31;
months["june"] = 30;
months["july"] = 31;
months["august"] = 31;
months["september"] = 30;
months["october"] = 31;
months["november"] = 30;
months["december"] = 31;
cout << "june -> " << months["june"] << endl;
map<const char*, int, ltstr>::iterator cur = months.find("june");
map<const char*, int, ltstr>::iterator prev = cur;
map<const char*, int, ltstr>::iterator next = cur;
++next;
--prev;
cout << "Previous (in alphabetical order) is " << (*prev).first << endl;
cout << "Next (in alphabetical order) is " << (*next).first << endl;
}
</pre>
<h3>Definition</h3>
<tt>Map</tt> is declared in <A href="map.h">map.h</A>. The implementation is in
<A href="map.h">map.h</A> and <A href="tree.h" tppabs="http://www.sgi.com/Technology/STL/tree.h">tree.h</A>.
<h3>Template parameters</h3>
<Table border>
<TR>
<TH>
Parameter
</TH>
<TH>
Description
</TH>
<TH>
Default
</TH>
</TR>
<TR>
<TD VAlign=top>
<tt>Key</tt>
</TD>
<TD VAlign=top>
The map's key type. This is also defined as <tt>map::key_type</tt>.
</TD>
<TD VAlign=top>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>Data</tt>
</TD>
<TD VAlign=top>
The map's data type. This is also defined as <tt>map::data_type</tt>.
</TD>
<TD VAlign=top>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>Compare</tt>
</TD>
<TD VAlign=top>
The key comparison function, a <A href="StrictWeakOrdering.html">Strict Weak Ordering</A> whose
argument type is <tt>key_type</tt>; it returns <tt>true</tt> if its first
argument is less than its second argument, and <tt>false</tt> otherwise.
This is also defined as <tt>map::key_compare</tt>.
</TD>
<TD VAlign=top>
<tt><A href="less.html">less</A><Key></tt>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>Alloc</tt>
</TD>
<TD VAlign=top>
The <tt>map</tt>'s allocator, used for all internal memory management.
</TD>
<TD VAlign=top>
<tt><A href="Allocators.html">alloc</A></tt>
</TD>
</tr>
</table>
<h3>Model of</h3>
<A href="UniqueSortedAssociativeContainer.html">Unique Sorted Associative Container</A>, <A href="PairAssociativeContainer.html" tppabs="http://www.sgi.com/Technology/STL/PairAssociativeContainer.shtml">Pair Associative Container</A>
<h3>Type requirements</h3>
<UL>
<LI>
<tt>Data</tt> is <A href="Assignable.html">Assignable</A>.
<LI>
<tt>Compare</tt> is a <A href="StrictWeakOrdering.html">Strict Weak Ordering</A> whose argument type
is <tt>Key</tt>.
<LI>
<tt>Alloc</tt> is an <A href="Allocators.html">Allocator</A>.
</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>key_type</tt>
</TD>
<TD VAlign=top>
<A href="AssociativeContainer.html">Associative Container</A>
</TD>
<TD VAlign=top>
The <tt>map</tt>'s key type, <tt>Key</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>data_type</tt>
</TD>
<TD VAlign=top>
<A href="PairAssociativeContainer.html">Pair Associative Container</A>
</TD>
<TD VAlign=top>
The type of object associated with the keys.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>value_type</tt>
</TD>
<TD VAlign=top>
<A href="PairAssociativeContainer.html">Pair Associative Container</A>
</TD>
<TD VAlign=top>
The type of object, <tt>pair<const key_type, data_type></tt>, stored in the map.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>key_compare</tt>
</TD>
<TD VAlign=top>
<A href="SortedAssociativeContainer.html">Sorted Associative Container</A>
</TD>
<TD VAlign=top>
<A href="functors.html">Function object</A> that compares two keys for ordering.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>value_compare</tt>
</TD>
<TD VAlign=top>
<A href="SortedAssociativeContainer.html">Sorted Associative Container</A>
</TD>
<TD VAlign=top>
<A href="functors.html">Function object</A> that compares two values for ordering.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>pointer</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Pointer to <tt>T</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>reference</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Reference to <tt>T</tt>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_reference</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Const reference to <tt>T</tt>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>size_type</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
An unsigned integral type.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>difference_type</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
A signed integral type.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>iterator</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Iterator used to iterate through a <tt>map</tt>. <A href="#1">[1]</A>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_iterator</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Const iterator used to iterate through a <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>reverse_iterator</tt>
</TD>
<TD VAlign=top>
<A href="ReversibleContainer.html">Reversible Container</A>
</TD>
<TD VAlign=top>
Iterator used to iterate backwards through a <tt>map</tt>. <A href="#1">[1]</A>
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_reverse_iterator</tt>
</TD>
<TD VAlign=top>
<A href="ReversibleContainer.html">Reversible Container</A>
</TD>
<TD VAlign=top>
Const iterator used to iterate backwards through a <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>iterator begin()</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Returns an <tt>iterator</tt> pointing to the beginning of the <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>iterator end()</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Returns an <tt>iterator</tt> pointing to the end of the <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_iterator begin() const</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Returns a <tt>const_iterator</tt> pointing to the beginning of the <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_iterator end() const</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Returns a <tt>const_iterator</tt> pointing to the end of the <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>reverse_iterator rbegin()</tt>
</TD>
<TD VAlign=top>
<A href="ReversibleContainer.html">Reversible Container</A>
</TD>
<TD VAlign=top>
Returns a <tt>reverse_iterator</tt> pointing to the beginning of the
reversed map.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>reverse_iterator rend()</tt>
</TD>
<TD VAlign=top>
<A href="ReversibleContainer.html">Reversible Container</A>
</TD>
<TD VAlign=top>
Returns a <tt>reverse_iterator</tt> pointing to the end of the
reversed map.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_reverse_iterator rbegin() const</tt>
</TD>
<TD VAlign=top>
<A href="ReversibleContainer.html">Reversible Container</A>
</TD>
<TD VAlign=top>
Returns a <tt>const_reverse_iterator</tt> pointing to the beginning of the
reversed map.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>const_reverse_iterator rend() const</tt>
</TD>
<TD VAlign=top>
<A href="ReversibleContainer.html">Reversible Container</A>
</TD>
<TD VAlign=top>
Returns a <tt>const_reverse_iterator</tt> pointing to the end of the
reversed map.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>size_type size() const</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Returns the size of the <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>size_type max_size() const</tt>
</TD>
<TD VAlign=top>
<A href="Container.html">Container</A>
</TD>
<TD VAlign=top>
Returns the largest possible size of the <tt>map</tt>.
</TD>
</TR>
<TR>
<TD VAlign=top>
<tt>bool empty() const</tt>
</TD>
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