C++ Tutorial/STL Algorithms Merge/set difference — различия между версиями
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Версия 17:21, 25 мая 2010
Determine elements in one set but not in another set
<source lang="cpp">#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;
}</source>
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()
<source lang="cpp">/* 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;
}</source>
c1: 1 2 2 4 6 7 7 9 c2: 2 2 2 3 6 6 8 9 set_difference(): 1 4 7 7
includes, set_difference, set_intersection, set_symmetric_difference and set_union.
<source lang="cpp">#include <iostream>
- include <algorithm>
using namespace std; 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, 5, 6, 11, 15 }; if ( includes( a1, a1 + SIZE1, a2, a2 + SIZE2 ) ) cout << "\na1 includes a2"; else cout << "\na1 does not include a2"; if ( includes( a1, a1 + SIZE1, a3, a3 + SIZE2 ) ) cout << "\na1 includes a3"; else cout << "\na1 does not include a3"; int difference[ SIZE1 ]; int *ptr = set_difference( a1, a1 + SIZE1, a2, a2 + SIZE2, difference ); int intersection[ SIZE1 ]; ptr = set_intersection( a1, a1 + SIZE1, a2, a2 + SIZE2, intersection ); int symmetric_difference[ SIZE1 ]; ptr = set_symmetric_difference( a1, a1 + SIZE1,a2, a2 + SIZE2, symmetric_difference ); int unionSet[ SIZE3 ]; ptr = set_union( a1, a1 + SIZE1, a3, a3 + SIZE2, unionSet ); return 0;
}</source>