STL set

#include <set>
#include <iostream>
#include <algorithm>
#include <string.h>

using namespace std;

struct ltstr
{
  bool operator()(const char* s1, const char* s2) const
  {
    return strcmp(s1, s2) < 0;
  }
};

int main()
{
  const int N = 6;
  const char* a[N] = {"isomer", "ephemeral", "prosaic", 
                      "nugatory", "artichoke", "serif"};
  const char* b[N] = {"flat", "this", "artichoke",
                      "frigate", "prosaic", "isomer"};

  set<const char*, ltstr> A(a, a + N);
  set<const char*, ltstr> B(b, b + N);
  set<const char*, ltstr> C;

  cout << "Set A: ";
  copy(A.begin(), A.end(), ostream_iterator<const char*>(cout, " "));
  cout << endl;
  cout << "Set B: ";
  copy(B.begin(), B.end(), ostream_iterator<const char*>(cout, " "));   
  cout << endl;

  cout << "Union: ";
  set_union(A.begin(), A.end(), B.begin(), B.end(),
            ostream_iterator<const char*>(cout, " "),
            ltstr());   
  cout << endl;

  cout << "Intersection: ";
  set_intersection(A.begin(), A.end(), B.begin(), B.end(),
                   ostream_iterator<const char*>(cout, " "),
                   ltstr());    
  cout << endl;

  set_difference(A.begin(), A.end(), B.begin(), B.end(),
                 inserter(C, C.begin()),
                 ltstr());
  cout << "Set C (difference of A and B): ";
  copy(C.begin(), C.end(), ostream_iterator<const char*>(cout, " "));
  cout << endl;
}