random_shuffle(3C++) - random_shuffle(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMErandom_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 generating function object rand (where rand takes a posi‐
tive argument 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 OutputElements 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 parameters, you
always need to supply the Allocator template argument. For instance,
you need to write:
vector<int, allocator<int> >
instead of:
vector<int>
If your compiler does not support namespaces, then you do not need the
using declaration for std.
Rogue Wave Software 02 Apr 1998 random_shuffle(3C++)
