void merge (string alpha, string beta)
{
	string temp;
	string temp2;
	stringstream insert(alpha);
    stringstream insert2(beta); // Insert the string into a stream
	ostream_iterator<string> output(cout, " ");
 
    vector<string> words; //vector to hold words
	vector<string> words2;
	vector<string> results;
 
	while (insert >> temp)
        words.push_back(temp);
 
	while (insert2 >> temp2)
        words2.push_back(temp2);
 
	merge(words.begin(), words.end(), words2.begin(), words2.end(), results.begin());
 
	cout<<"Merge contains:";
		copy(results.begin(), results.end(), output );
 
}

merge(
  words.begin(), words.end(), // OK
  words2.begin(), words2.end(), // OK
  results.begin()); // Oops! results is empty

merge ( 
  words.begin(), words.end(), 
  words2.begin(), words2.end(), 
  back_inserter ( results ) );

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>
#include <algorithm>
#include <iterator>
 
using namespace std;
 
//prototype of split function
void SplitLines (string& a);
void SplitLines2 (string& b);
void AunionB (string a, string b);
void AinterectB ();
void AdifferenceB ();
 
 
 
int main()
{
   string fileName;
   string a;
   string b;
   int names = 0;
   ifstream myfile;
 
   cout << "Enter file name: ";// Get filename from user
   cin >> fileName;
 
 
   myfile.open(fileName.c_str());
 
 
   while(myfile.good() == false)// Prompt for new file name if not able to open
   {
      cout << "Unable to open file. Enter a different name: ";
	  myfile.clear();
      cin >> fileName;
      myfile.open(fileName.c_str());
 
   }
 
   while (!myfile.eof()) 
   {  
	   getline(myfile,a, '\n');
	   getline(myfile,b, '\n');
	   //function call to split lines into words
	   SplitLines(a);
	   cout<<endl;
	   SplitLines2(b);
	   cout<<endl;
	   AunionB (a, b);
   } 
   myfile.close();
   return 0;
}
//name of fucntion for splitting
void SplitLines (string& a)
{
	string temp;
    stringstream insert(a); // Insert the string into a stream
 
    vector<string> words; //vector to hold words
 
    while (insert >> temp)
        words.push_back(temp);
	cout<<"Set A: {";
	 for( int i = 0; i < words.size(); i++ ) {
		 cout<< words[i] <<","<< " ";
     }
	 cout<<"}";
}
void SplitLines2 (string& b)
{
	string temp;
    stringstream insert(b); // Insert the string into a stream
 
    vector<string> words; //vector to hold words
 
    while (insert >> temp)
        words.push_back(temp);
	cout<<"Set B: {";
   for( int i = 0; i < words.size(); i++ ) {//print vector to screen
   cout << words[i]  <<","<< " ";
   }
	cout<<"}";
}
void AunionB (string a, string b)
{
	string temp;
	string temp2;
	stringstream insert(a);
    stringstream insert2(b); // Insert the string into a stream
	ostream_iterator<string> output(cout, " ");
 
    vector<string> words; //vector to hold words
	vector<string> words2;
 
 
	while (insert >> temp)
        words.push_back(temp);
 
	while (insert2 >> temp2)
        words2.push_back(temp2);
 
		vector<string> results(words.size() + words2.size());
 
	merge(words.begin(), words.end(), words2.begin(), words2.end(), results.begin());
 
	cout<<"Merge contains:";
		copy(results.begin(), results.end(), output );
 
}