Man Page random_shuffle.3

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

```

NAME

```     random_shuffle

- Randomly shuffles elements of a collection.

```

SYNOPSIS

```     #include <algorithm>
template <class RandomAccessIterator>
void random_shuffle (RandomAccessIterator first,
RandomAccessIterator last);

template <class RandomAccessIterator,
class RandomNumberGenerator>
void random_shuffle (RandomAccessIterator first,
RandomAccessIterator last,
RandomNumberGenerator& rand);

```

DESCRIPTION

```     The random_shuffle algorithm shuffles the  elements  in  the
range    [first,    last)    with    uniform   distribution.
random_shuffle can take a particular random number  generat-
ing  function object rand (where rand takes a positive argu-
ment n of distance type  of  the  RandomAccessIterator)  and
returns a randomly chosen value between 0 and n - 1.

```

COMPLEXITY

```     In the random_shuffle algorithm, (last - first) -1 swaps are
done.

```

EXAMPLE

```     //
// rndshufl.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 random_shuffle: " << endl
<< "     ";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//Mix them up with random_shuffle
random_shuffle(v.begin(), v.end());
//Print out the mixed up elements
cout << "Elements after random_shuffle: "  <<  endl  <<  "
";
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl;

return 0;
}

Program Output

Elements before random_shuffle:
1 2 3 4 5 6 7 8 9 10
Elements after random_shuffle:
7 9 10 3 2 5 4 8 1 6

```

WARNINGS

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

vector<int, allocator<int> >