Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.

NAME

 
set_symmetric_difference
 
 - A basic set operation for constructing a sorted symmetric difference.
 
 
 

SYNOPSIS

 
 
#include <algorithm>
template <class InputIterator1, class InputIterator2,

class OutputIterator>

OutputIterator

    set_symmetric_difference (InputIterator1 first1,

InputIterator1 last1,
InputIterator2 first2,
InputIterator2 last2,
OutputIterator result);

template <class InputIterator1, class InputIterator2,

class OutputIterator, class Compare>

OutputIterator

    set_symmetric_difference (InputIterator1 first1,

InputIterator1 last1,
InputIterator2 first2,
InputIterator2 last2,
OutputIterator result,
Compare comp);
 
 
 

DESCRIPTION

 
 
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 [first1, last1) (but not present in the range [first2, last2)) and copies of the elements that are present in the range [first2, last2) (but not in the range [first1, last1)). 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 the default comparison operator less than (<), unless an alternative comparison operator (comp) is provided. 
 
Use the set_symmetric_difference algorithm to return a result that includes elements that are present in the first set and not in the second.
 
 
 

COMPLEXITY

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

EXAMPLE

//
// set_s_di.cpp
//
#include<algorithm>
#include<set>
#include <istream.h>
using namespace std;
 
int main()

{

 
//Initialize some sets
int a1[] = {1,3,5,7,9,11};
int a3[] = {3,5,7,8};
set<int, less<int> > odd(a1+0,a1+6), result,

small(a3+0,a3+4);

//Create an insert_iterator for result
insert_iterator<set<int, less<int> > >

res_ins(result, result.begin());

//Demonstrate set_symmetric_difference
cout << "The symmetric difference of:" << endl << "{";
copy(small.begin(),small.end(),

ostream_iterator<int,char>(cout," "));

cout << "} with {";
copy(odd.begin(),odd.end(),

ostream_iterator<int,char>(cout," "));

cout << "} =" << endl << "{";
set_symmetric_difference(small.begin(), small.end(),

odd.begin(), odd.end(), res_ins);

copy(result.begin(),result.end(),

ostream_iterator<int,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 }
 
 
 

WARNINGS

 
 
If your compiler does not support default template parameters, then you always need to supply the Compare template argument and the Allocator template argument. For instance, you need to write:
 
set<int, less<int>, allocator<int> >
 
instead of:
 
set<int>
 
If your compiler does not support namespaces, then you do not need the using declaration for std. 
 
 
 

SEE ALSO

 
 
includes, set, set_union,_set_intersection, set_difference
 

Rogue Wave Software  —  Last change: 02 Apr 1998