/*
  1-dim random walk program. 
  A walker makes several trials steps with
  a given number of walks per trial
*/
#include <iostream>
#include <fstream>
#include <iomanip>
#include "lib.h"
using namespace  std;

// Function to read in data from screen, note call by reference
void initialise(int&, int&, double&) ;
// The Mc sampling for random walks
void  mc_sampling(int, int, double, int *, int *);
// prints to screen the results of the calculations 
void  output(int, int, int *, int *);

int main()
{
  int max_trials, number_walks; 
  double move_probability;
  // Read in data 
  initialise(max_trials, number_walks, move_probability) ;
  int *walk_cumulative = new int [number_walks+1];
  int *walk2_cumulative = new int [number_walks+1];
  for (int walks = 1; walks <= number_walks; walks++){   
    walk_cumulative[walks] = walk2_cumulative[walks] = 0;
  } // end initialization of vectors
  // Do the mc sampling  
  mc_sampling(max_trials, number_walks, move_probability, 
              walk_cumulative, walk2_cumulative);
  // Print out results 
  output(max_trials, number_walks, walk_cumulative, 
         walk2_cumulative);
  delete [] walk_cumulative; // free memory
  delete [] walk2_cumulative; 
  return 0; 
} // end main function
\end{lstlisting}
The  input and output functions are 
\begin{lstlisting} 
void initialise(int& max_trials, int& number_walks, double& move_probability) 
{
  cout << "Number of Monte Carlo trials ="; 
  cin >> max_trials;
  cout << "Number of attempted walks=";
  cin >> number_walks;
  cout << "Move probability=";
  cin >> move_probability;
}  // end of function initialise