```
Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.

```

## NAME

```     advance

- Moves an iterator forward or backward (if available) by a
certain distance.

```

## SYNOPSIS

```     #include <iterator>
template <class InputIterator, class Distance>
void advance (InputIterator& i, Distance n);

```

## DESCRIPTION

```     The advance template  function  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
operator+ and operator- for constant  time  implementations.
For  input,  forward,  and  bidirectional iterators, advance
uses operator++ for  linear  time  implementations.  advance
also uses operator-- with bidirectional iterators for linear
time implementations of negative distances.

If n is positive, advance increments iterator reference i by
n.  For negative n, advance decrements reference i. Remember
that advance accepts a negative argument n for random access
and bidirectional iterators only.

```

## EXAMPLE

```     //
//
#include<iterator>
#include<list>
#include<iostream>
using namespace std;

int main()
{

//
//Initialize a list using an array
//
int arr[6] = {3,4,5,6,7,8};
list<int> l(arr,arr+6);
//
//Declare a list iterator, s.b. a ForwardIterator
//
list<int>::iterator itr = l.begin();
//
//Output the original list
//
cout << "For the list: ";
copy(l.begin(),l.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
cout << "When the iterator is initialized to l.begin(),"
<< endl << "it points to " << *itr << endl << endl;
//
// operator+ is not available for a ForwardIterator,
//

cout << "After advance(itr,4), the iterator points to "
<< *itr << 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

```

## WARNINGS

```     If your compiler does not support default  template  parame-
ters,  then you always need to supply the Allocator template
argument. For instance, you have to write:

vector<int,allocator<int> >

vector<int>
If your compiler does not support namespaces,  then  you  do
not need the using declaration for std.

```

```     Sequences, Random_Access_Iterators, distance

```