C++/STL Algorithms Merge/set difference
Determine elements in one set but not in another set
#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <iterator>
int main()
{
const int SIZE1 = 10, SIZE2 = 5, SIZE3 = 20;
int a1[ SIZE1 ] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
int a2[ SIZE2 ] = { 4, 5, 6, 7, 8 };
int a3[ SIZE2 ] = { 4, 7, 6, 11, 15 };
std::ostream_iterator< int > output( cout, " " );
cout << "a1 contains: ";
std::copy( a1, a1 + SIZE1, output );
cout << "\na2 contains: ";
std::copy( a2, a2 + SIZE2, output );
cout << "\na3 contains: ";
std::copy( a3, a3 + SIZE2, output );
int difference[ SIZE1 ];
int *ptr = std::set_difference( a1, a1 + SIZE1, a2, a2 + SIZE2, difference );
cout << "\n\nset_difference of a1 and a2 is: ";
std::copy( difference, ptr, output );
return 0;
}
/*
a1 contains: 1 2 3 4 5 6 7 8 9 10
a2 contains: 4 5 6 7 8
a3 contains: 4 7 6 11 15
set_difference of a1 and a2 is: 1 2 3 9 10
*/
Determine elements of first range without elements of second range by using set_difference()
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <string>
#include <algorithm>
#include <iterator>
#include <functional>
#include <numeric>
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << " ";
}
std::cout << std::endl;
}
/* INSERT_ELEMENTS (collection, first, last)
* - fill values from first to last into the collection
* - NOTE: NO half-open range
*/
template <class T>
inline void INSERT_ELEMENTS (T& coll, int first, int last)
{
for (int i=first; i<=last; ++i) {
coll.insert(coll.end(),i);
}
}
using namespace std;
int main()
{
int c1[] = { 1, 2, 2, 4, 6, 7, 7, 9 };
int num1 = sizeof(c1) / sizeof(int);
int c2[] = { 2, 2, 2, 3, 6, 6, 8, 9 };
int num2 = sizeof(c2) / sizeof(int);
// print source ranges
cout << "c1: " ;
copy (c1, c1+num1, ostream_iterator<int>(cout," "));
cout << endl;
cout << "c2: " ;
copy (c2, c2+num2, ostream_iterator<int>(cout," "));
cout << "\n" << endl;
// determine elements of first range without elements of second range by using set_difference()
cout << "set_difference(): ";
set_difference (c1, c1+num1, c2, c2+num2, ostream_iterator<int>(cout," "));
cout << endl;
}
/*
c1: 1 2 2 4 6 7 7 9
c2: 2 2 2 3 6 6 8 9
set_difference(): 1 4 7 7
*/