Random shuffle function is used to randomly rearrange the elements in a given range. The random_shuffle function is defined in the STL algorithm.

Template for random_shuffle

template <class InputIterator>
  void random_shuffle (InputIterator first, InputIterator last);

About parameters
InputIterator first
InputIterator first for the initial position of the range which is included in the range.
InputIterator last
InputIterator last for the final position which it not included in the range.

A sample program using random_shuffle

#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

int main()
{
        vector <int> v;
        vector <int>:: iterator it;

        // Pushing 11 random elements inside the vector
        v.push_back(1);
        v.push_back(2);
        v.push_back(3);
        v.push_back(4);
        v.push_back(5);
        v.push_back(6);
        v.push_back(7);
        v.push_back(8);
        v.push_back(9);
        v.push_back(10);
        v.push_back(11);

        // printing the elemnets inside the range
        cout <<"Elements inside the range." << endl;
        for ( it = v.begin(); it != v.end(); it++)
                cout << *it << " ";
        cout << endl;

        //applying random_shuffle function on the range
        random_shuffle(v.begin(),v.end());

        // printing the elemnets inside the range
        cout <<"Elements inside the range after random shuffle." << endl;
        for ( it = v.begin(); it != v.end(); it++)
                cout << *it << " ";
        cout << endl;

        return 0;
}

Output of the above program

Elements inside the range.
1 2 3 4 5 6 7 8 9 10 11 
Elements inside the range after random shuffle.
5 11 8 9 1 6 3 2 7 10 4 

Time complexity for random_shuffle is linear in the distance between the range.