includes

     Algorithm

Basic set operation for sorted sequences.

Contents

• Synopsis
• Description
• Complexity
• Example
• Warnings
• See Also

#include <algorithm>

template <class InputIterator1, class InputIterator2>
 bool includes (InputIterator1 first1, InputIterator1 last1,
                InputIterator2 first2, InputIterator2 last2);
template <class InputIterator1, class InputIterator2, class Compare>
 bool includes (InputIterator1 first1, InputIterator1 last1,
                InputIterator2 first2, InputIterator2 last2, 
                Compare comp);

The includes algorithm compares two sorted sequences and returns true if every element in the range [first2, last2) is contained in the range [first1, last1). It returns false otherwise. includes assumes that the sequences are sorted using the default comparison operator less than (<), unless an alternative comparison operator (comp) is provided.

At most ((last1 - first1) + (last2 - first2)) * 2 -1 comparisons are performed.

//
// includes.cpp 
//
 #include <algorithm>
 #include <set>
 #include <iostream.h>
 int main()
 {
   //Initialize some sets
   int a1[10] = {1,2,3,4,5,6,7,8,9,10};
   int a2[6]  = {2,4,6,8,10,12};
   int a3[4]  = {3,5,7,8};
   set<int, less<int> > all(a1, a1+10), even(a2, a2+6), 
                         small(a3,a3+4);
  //Demonstrate includes
  cout << "The set: ";
  copy(all.begin(),all.end(),
        ostream_iterator<int>(cout," "));
  bool answer = includes(all.begin(), all.end(), 
                small.begin(), small.end());
  cout << endl 
       << (answer ? "INCLUDES " : "DOES NOT INCLUDE ");
  copy(small.begin(),small.end(),
        ostream_iterator<int>(cout," "));
  answer = includes(all.begin(), all.end(), 
                    even.begin(), even.end());
  cout << ", and" << endl 
       << (answer ? "INCLUDES" : "DOES NOT INCLUDE ");
  copy(even.begin(),even.end(),
        ostream_iterator<int>(cout," "));
  cout << endl << endl;
  return 0;
 }
Output :
The set: 1 2 3 4 5 6 7 8 9 10
INCLUDES 3 5 7 8 , and
DOES NOT INCLUDE 2 4 6 8 10 12

If your compiler does not support default template parameters, then you need to always supply the Allocator template argument. For instance, you'll have to write :

set<int, less<int>, allocator>

instead of

set<int>

set, set_union, set_intersection, set_difference, set_symmetric_difference