set_difference(3C++) - set_difference(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEset_difference
- A basic set operation for constructing a sorted difference.
SYNOPSIS
#include <algorithm>
template <class InputIterator1, class InputIterator2,
class OutputIterator>
OutputIterator
set_difference (InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
InputIterator2 last2,
OutputIterator result);
template <;class InputIterator1, class InputIterator2,
class OutputIterator, class Compare>
OutputIterator
set_difference (InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
InputIterator2 last2,
OutputIterator result, Compare comp);
DESCRIPTION
The set_difference algorithm constructs a sorted difference that
includes copies of the elements that are present in the range [first1,
last1) but are not present in the range [first2, last2). It returns the
end of the constructed range.
As an example, assume we have the following two sets:
1 2 3 4 5
and
3 4 5 6 7
The result of applying set_difference is the set:
1 2
The result of set_difference is undefined if the result range overlaps
with either of the original ranges.
set_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_symetric_difference algorithm to return a result that con‐
tains all elements that are not in common between the two sets.
COMPLEXITY
At most ((last1 - first1) + (last2 - first2)) * 2 -1 comparisons are
performed.
EXAMPLE
//
// set_diff.cpp
//
#include <algorithm>
#include <set>
#include <iostream>
using namespace std;
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};
set<;int, less<int> > all(a1+0, a1+10), even(a2+0, a2+6),
odd;
//Create an insert_iterator for odd
insert_iterator<;set<int, less<int> > >
odd_ins(odd, odd.begin());
//Demonstrate set_differencecout <;< "The result of:" << endl << "{";
copy(all.begin(),all.end(),
ostream_iterator<int,char>(cout," "));
cout <;< "} - {";
copy(even.begin(),even.end(),
ostream_iterator<int,char>(cout," "));
cout <;< "} =" << endl << "{";
set_difference(all.begin(), all.end(),
even.begin(), even.end(), odd_ins);
copy(odd.begin(),odd.end(),
ostream_iterator<int,char>(cout," "));
cout <;< "}" << endl << endl;
return 0;
}
Program OutputThe result of:
{1 2 3 4 5 6 7 8 9 10 } - {2 4 6 8 10 12 } =
{1 3 5 7 9 }
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_symmetric_difference
Rogue Wave Software 02 Apr 1998 set_difference(3C++)
