Module: Standard C++ Library Library: Algorithms
Function
A basic set operation (algorithm) for constructing a sorted symmetric difference
#include <algorithm>
namespace std {
template <class InputIterator1, class InputIterator2,
class OutputIterator>
OutputIterator
set_symmetric_difference(InputIterator1 start1,
InputIterator1 finish1,
InputIterator2 start2,
InputIterator2 finish2,
OutputIterator result);
template <class InputIterator1, class InputIterator2,
class OutputIterator, class Compare>
OutputIterator
set_symmetric_difference(InputIterator1 start1,
InputIterator1 finish1,
InputIterator2 start2,
InputIterator2 finish2,
OutputIterator result,
Compare comp);
}
The algorithm set_symmetric_difference() constructs a sorted symmetric difference of the elements from the two ranges. This means that the constructed range includes copies of the elements that are present in the range [start1, finish1) (but not present in the range [start2, finish2)) and copies of the elements that are present in the range [start2, finish2) (but not in the range [start1, finish1)). It returns the end of the constructed range.
For example, suppose we have two sets:
1 2 3 4 5
and
3 4 5 6 7
The set_symmetric_difference() of these two sets is:
1 2 6 7
The result of set_symmetric_difference() is undefined if the result range overlaps with either of the original ranges.
set_symmetric_difference() assumes that the ranges are sorted using operator<(), unless an alternative comparison function object (comp) is provided.
Use the set_symmetric_difference() algorithm to obtain a result that includes elements that are present in the first set and not in the second.
At most ((finish1 - start1) + (finish2 - start2)) * 2 -1 comparisons are performed.
//
// set_s_di.cpp
//
#include <algorithm>
#include <set>
#include <iostream>
int main ()
{
#ifndef _RWSTD_NO_NAMESPACE
using namespace std;
#endif
// Initialize some sets.
int a1[] = {1,3,5,7,9,11};
int a3[] = {3,5,7,8};
set<int, less<int>,allocator<int> > odd(a1+0, a1+6),
result,
smalll(a3+0, a3+4);
// Create an insert_iterator for result.
insert_iterator<set<int, less<int>,allocator<int> > >
res_ins(result, result.begin());
// Demonstrate set_symmetric_difference.
cout << "The symmetric difference of:" << endl << "{";
copy(smalll.begin(),smalll.end(),
ostream_iterator<int,char,char_traits<char> >
(cout," "));
cout << "} with {";
copy(odd.begin(),odd.end(),
ostream_iterator<int,char,char_traits<char> >
(cout," "));
cout << "} =" << endl << "{";
set_symmetric_difference(smalll.begin(), smalll.end(),
odd.begin(), odd.end(), res_ins);
copy(result.begin(),result.end(),
ostream_iterator<int,char,char_traits<char> >
(cout," "));
cout << "}" << endl << endl;
return 0;
}
Program Output:
The symmetric difference of:
{3 5 7 8 } with {1 3 5 7 9 11 } =
{1 8 9 11 }
includes(), Iterators, set_union(), set_intersection(), set_difference()
ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.3.5.5
Copyright (c) 1994-2006 Rogue Wave Software, a Quovadx Division.
Licensed under the Apache License, Version 2.0.
Contact Rogue Wave about documentation or support issues. You can also seek help from other developers through the Apache stdcxx community (see below).