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 <H2>advance()</H2>
 <P><B>Library:</B>&nbsp;&nbsp;<A HREF="2-8.html">Iterators</A></P>

 <PRE><HR><B><I>Function</I></B><HR></PRE>

 <UL>
 <LI><A HREF="#sec1">Local Index</A></LI>
 <LI><A HREF="#sec2">Summary</A></LI>
 <LI><A HREF="#sec3">Synopsis</A></LI>
 <LI><A HREF="#sec4">Description</A></LI>
 <LI><A HREF="#sec5">Example</A></LI>
 <LI><A HREF="#sec6">See Also</A></LI>
 <LI><A HREF="#sec7">Standards Conformance</A></LI>
 </UL>
 <A NAME="sec1"><H3>Local Index</H3></A>
 No Entries
 <A NAME="sec2"><H3>Summary</H3></A>
 <P>A function that advances an iterator forward or backward (if available) by a certain distance</P>
 <A NAME="sec3"><H3>Synopsis</H3></A>

 <PRE>#include &lt;iterator&gt;

 namespace std {
   template &lt;class InputIterator, class Distance&gt;
   void advance(InputIterator&amp; i, Distance n);
 }
 </PRE>
 <A NAME="sec4"><H3>Description</H3></A>
 <P>The <SAMP>advance()</SAMP> function template allows an iterator to be advanced through a container by some arbitrary distance. For bidirectional and random access iterators, this distance may be negative. For random access iterators, this function uses <SAMP>operator+=()</SAMP> and <SAMP>operator-=()</SAMP> for constant time implementations. For input, forward, and bidirectional iterators, <SAMP>advance()</SAMP> uses <SAMP>operator++()</SAMP> for linear time implementations. <SAMP>advance()</SAMP> also uses <SAMP>operator--()</SAMP> with bidirectional iterators for linear time implementations of negative distances. </P>
 <P>If <SAMP>n</SAMP> is positive, <SAMP>advance()</SAMP> increments iterator reference <SAMP>i</SAMP> by <SAMP>n</SAMP>. For&nbsp;negative&nbsp;<SAMP>n</SAMP>, <SAMP>advance()</SAMP> decrements reference <SAMP>i</SAMP>. Remember that <SAMP>advance()</SAMP> accepts a negative argument <SAMP>n</SAMP> for random access and bidirectional iterators only.</P>
 <A NAME="sec5"><H3>Example</H3></A>

 <UL><PRE>//
 // advance.cpp
 //

 #include &lt;iterator&gt;   // for advance
 #include &lt;iostream&gt;   // for cout, endl
 #include &lt;list&gt;       // for list


 int main ()
 {
     // Typedefs for convenience.
     typedef std::list&lt;long, std::allocator&lt;long&gt; &gt; list;
     typedef std::ostream_iterator&lt;list::value_type, char,
                               std::char_traits&lt;char&gt; &gt; os_iter;

     // Initialize a list using an array.
     const list::value_type arr [] = { 3, 4, 5, 6, 7, 8 };
     list l (arr + 0, arr + sizeof arr / sizeof *arr);

     // Declare a list iterator, s.b. a ForwardIterator.
     list::iterator itr = l.begin ();

     // Output the original list.
     std::cout &lt;&lt; "For the list: ";
     std::copy (l.begin (), l.end (), os_iter (std::cout, " "));

     std::cout &lt;&lt; std::endl &lt;&lt; std::endl
           &lt;&lt; "When the iterator is initialized to l.begin (),"
           &lt;&lt; "\nit points to " &lt;&lt; *itr &lt;&lt; std::endl;

     // operator+ is not available for a ForwardIterator,
     // so use advance.
     std::advance (itr, 4);
     std::cout
       &lt;&lt; "\nAfter advance (itr, 4), the iterator points to "
       &lt;&lt; *itr &lt;&lt; std::endl;

     return 0;
 }

 Program Output:
 For the list: 3 4 5 6 7 8

 When the iterator is initialized to l.begin (),
 it points to 3

 After advance (itr, 4), the iterator points to 7
 </PRE></UL>
 <A NAME="sec6"><H3>See Also</H3></A>
 <P><A HREF="sequences.html">Sequences</A>, <A HREF="randomaccessiterators.html">Random Access Iterators</A>, <SAMP><A HREF="distance.html">distance()</A></SAMP></P>
 <A NAME="sec7"><H3>Standards Conformance</H3></A>
 <P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 24.3.4</I></P>

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	<H2>advance()</H2>
	<P><B>Library:</B>  <A HREF="2-8.html">Iterators</A></P>

	<PRE><HR><B><I>Function</I></B><HR></PRE>

	<UL>
	<LI><A HREF="#sec1">Local Index</A></LI>
	<LI><A HREF="#sec2">Summary</A></LI>
	<LI><A HREF="#sec3">Synopsis</A></LI>
	<LI><A HREF="#sec4">Description</A></LI>
	<LI><A HREF="#sec5">Example</A></LI>
	<LI><A HREF="#sec6">See Also</A></LI>
	<LI><A HREF="#sec7">Standards Conformance</A></LI>
	</UL>
	<A NAME="sec1"><H3>Local Index</H3></A>
	No Entries
	<A NAME="sec2"><H3>Summary</H3></A>
	<P>A function that advances an iterator forward or backward (if available) by a certain distance</P>
	<A NAME="sec3"><H3>Synopsis</H3></A>

	<PRE>#include <iterator>

	namespace std {
	template <class InputIterator, class Distance>
	void advance(InputIterator& i, Distance n);
	}
	</PRE>
	<A NAME="sec4"><H3>Description</H3></A>
	<P>The <SAMP>advance()</SAMP> function template allows an iterator to be advanced through a container by some arbitrary distance. For bidirectional and random access iterators, this distance may be negative. For random access iterators, this function uses <SAMP>operator+=()</SAMP> and <SAMP>operator-=()</SAMP> for constant time implementations. For input, forward, and bidirectional iterators, <SAMP>advance()</SAMP> uses <SAMP>operator++()</SAMP> for linear time implementations. <SAMP>advance()</SAMP> also uses <SAMP>operator--()</SAMP> with bidirectional iterators for linear time implementations of negative distances. </P>
	<P>If <SAMP>n</SAMP> is positive, <SAMP>advance()</SAMP> increments iterator reference <SAMP>i</SAMP> by <SAMP>n</SAMP>. For negative <SAMP>n</SAMP>, <SAMP>advance()</SAMP> decrements reference <SAMP>i</SAMP>. Remember that <SAMP>advance()</SAMP> accepts a negative argument <SAMP>n</SAMP> for random access and bidirectional iterators only.</P>
	<A NAME="sec5"><H3>Example</H3></A>

	<UL><PRE>//
	// advance.cpp
	//

	#include <iterator> // for advance
	#include <iostream> // for cout, endl
	#include <list> // for list



	int main ()
	{
	// Typedefs for convenience.
	typedef std::list<long, std::allocator<long> > list;
	typedef std::ostream_iterator<list::value_type, char,
	std::char_traits<char> > os_iter;

	// Initialize a list using an array.
	const list::value_type arr [] = { 3, 4, 5, 6, 7, 8 };
	list l (arr + 0, arr + sizeof arr / sizeof *arr);

	// Declare a list iterator, s.b. a ForwardIterator.
	list::iterator itr = l.begin ();

	// Output the original list.
	std::cout << "For the list: ";
	std::copy (l.begin (), l.end (), os_iter (std::cout, " "));

	std::cout << std::endl << std::endl
	<< "When the iterator is initialized to l.begin (),"
	<< "\nit points to " << *itr << std::endl;

	// operator+ is not available for a ForwardIterator,
	// so use advance.
	std::advance (itr, 4);
	std::cout
	<< "\nAfter advance (itr, 4), the iterator points to "
	<< *itr << std::endl;

	return 0;
	}

	Program Output:
	For the list: 3 4 5 6 7 8

	When the iterator is initialized to l.begin (),
	it points to 3

	After advance (itr, 4), the iterator points to 7
	</PRE></UL>
	<A NAME="sec6"><H3>See Also</H3></A>
	<P><A HREF="sequences.html">Sequences</A>, <A HREF="randomaccessiterators.html">Random Access Iterators</A>, <SAMP><A HREF="distance.html">distance()</A></SAMP></P>
	<A NAME="sec7"><H3>Standards Conformance</H3></A>
	<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 24.3.4</I></P>

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