set_intersection(3C++) - set_intersection(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEset_intersection
- A basic set operation for constructing a sorted intersection.
SYNOPSIS
#include <algorithm>
template <class InputIterator1, class InputIterator2,
class OutputIterator>
OutputIterator
set_intersection (InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
InputIterator last2,
OutputIterator result);
template <;class InputIterator1, class InputIterator2,
class OutputIterator, class Compare>
OutputIterator
set_intersection (InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
InputIterator2 last2,
OutputIterator result, Compare comp);
DESCRIPTION
The set_intersection algorithm constructs a sorted intersection of ele‐
ments from the two ranges. It returns the end of the constructed range.
When it finds an element present in both ranges, set_intersection
always copies the element from the first range into result. This means
that the result of set_intersection is guaranteed to be stable. The
result of set_intersection is undefined if the result range overlaps
with either of the original ranges.
set_intersection assumes that the ranges are sorted using the default
comparison operator less than (<), unless an alternative comparison
operator (comp) is provided.
COMPLEXITY
At most ((last1 - first1) + (last2 - first2)) * 2 -1 comparisons are
performed.
EXAMPLE
//
// set_intr.cpp
//
#include <algorithm>
#include <set>
#include <iostream>
using namespace std;
int main()
{
//Initialize some sets
int a1[10] = {1,3,5,7,9,11};
int a3[4] = {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_intersectioncout <;< "The result of:" << endl << "{";
copy(small.begin(),small.end(),
ostream_iterator<int,char>(cout," "));
cout <;< "} intersection {";
copy(odd.begin(),odd.end(),
ostream_iterator<int,char>(cout," "));
cout <;< "} =" << endl << "{";
set_intersection(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 OutputThe result of:
{3 5 7 8 } intersection {1 3 5 7 9 11 } =
{3 5 7 }
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_difference, set_symmetric_difference
Rogue Wave Software 02 Apr 1998 set_intersection(3C++)
