Man Page reverse.3

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

```

NAME

```     reverse

- Reverses the order of elements in a collection.

```

SYNOPSIS

```     #include <algorithm>
template <class BidirectionalIterator>
void reverse (BidirectionalIterator first,
BidirectionalIterator last);

```

DESCRIPTION

```     The algorithm reverse reverses the elements in a sequence so
that the last element becomes the new first element, and the
first element becomes the new last.  For  each  non-negative
integer  i  <= (last - first)/2, reverse applies swap to all
pairs of iterators first + I, (last - I) - 1.

Because the  iterators  are  assumed  to  be  bidirectional,
reverse does not return anything.

```

COMPLEXITY

```     reverse performs exactly (last - first)/2 swaps.

```

EXAMPLE

```     //
// reverse.cpp
//
#include <algorithm>
#include <vector>
#include <iostream>
using namespace std;
int main()
{
//Initialize a vector with an array of ints
int arr[10] = {1,2,3,4,5,6,7,8,9,10};
vector<int> v(arr, arr+10);

//Print out elements in original (sorted) order
cout << "Elements before reverse: " << endl << "     ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;

//Reverse the ordering
reverse(v.begin(), v.end());

//Print out the reversed elements
cout << "Elements after reverse: " << endl << "     ";

copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl;

return 0;
}

Program Output

Elements before reverse:
1 2 3 4 5 6 7 8 9 10
Elements after reverse:
10 9 8 7 6 5 4 3 2 1
A reverse_copy to cout:
1 2 3 4 5 6 7 8 9 10

```

WARNINGS

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

```

```     reverse_copy, swap

```