set_union (3C++std) - Tru64 UNIX
Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc. NAME
set_union - Basic set operation for sorted sequences.
SYNOPSIS
#include <algorithm>
template <class InputIterator1, class InputIterator2, class OutputIterator>
OutputIterator
set_union (InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result);
template <class InputIterator1, class InputIterator2,
class OutputIterator, class Compare>
OutputIterator
set_union (InputIterator1 first1, InputIterator1 last1,
InputIterator2 first2, InputIterator2 last2,
OutputIterator result, Compare comp);
DESCRIPTION
The set_union algorithm constructs a sorted union of the elements from the
two ranges. It returns the end of the constructed range. set_union is
stable, that is, if an element is present in both ranges, the one from the
first range is copied. The result of set_union is undefined if the result
range overlaps with either of the original ranges. Note that set_union
does not merge the two sorted sequences. If an element is present in both
sequences, only the element from the first sequence is copied to result.
(Use the merge algorithm to create an ordered merge of two sorted sequences
that contains all the elements from both sequences.)
set_union assumes that the sequences 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_unin.cpp
//
#include <algorithm>
#include <set>
#include <iostream.h>
int main()
{
//Initialize some sets
int a2[6] = {2,4,6,8,10,12};
int a3[4] = {3,5,7,8};
set<int, less<int> > even(a2, a2+6),
result, small(a3,a3+4);
//Create an insert_iterator for result
insert_iterator<set<int, less<int> > >
res_ins(result, result.begin());
//Demonstrate set_union
cout << "The result of:" << endl << "{";
copy(small.begin(),small.end(),
ostream_iterator<int,char>(cout," "));
cout << "} union {";
copy(even.begin(),even.end(),
ostream_iterator<int,char>(cout," "));
cout << "} =" << endl << "{";
set_union(small.begin(), small.end(),
even.begin(), even.end(), res_ins);
copy(result.begin(),result.end(),
ostream_iterator<int,char>(cout," "));
cout << "}" << endl << endl;
return 0;
}
Output :
The result of:
{3 5 7 8 } union {2 4 6 8 10 12 } =
{2 3 4 5 6 7 8 10 12 }
WARNING
If your compiler does not support default template parameters, then you
need to always supply the Compare template argument and the Allocator
template argument. For instance, you will need to write :
set<int, less<int>, allocator<int> >
instead of :
set<int>
SEE ALSO
includes, set, set_intersection, set_difference, set_symmetric_difference
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee
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