C++ Tutorial/STL Algorithms Modifying sequence operations/remove copy if
Версия от 14:21, 25 мая 2010; (обсуждение)
Copy elements from one vector to another vector, removing elements greater than 9 in the process
#include <iostream>
using std::cout;
using std::endl;
#include <algorithm>
#include <vector>
#include <iterator>
bool greater9( int );
int main()
{
int a[ 10 ] = { 10, 2, 10, 4, 16, 6, 14, 8, 12, 10 };
std::ostream_iterator< int > output( cout, " " );
std::vector< int > v4( a, a + 10 ); // copy of a
std::vector< int > c2( 10, 0 ); // instantiate vector c2
cout << "Vector v4 before removing all elements"
<< "\ngreater than 9 and copying:\n ";
std::copy( v4.begin(), v4.end(), output );
std::remove_copy_if( v4.begin(), v4.end(), c2.begin(), greater9 );
cout << "\nVector c2 after removing all elements"
<< "\ngreater than 9 from v4:\n ";
std::copy( c2.begin(), c2.end(), output );
cout << endl;
return 0;
}
bool greater9( int x )
{
return x > 9;
}Vector v4 before removing all elements greater than 9 and copying: 10 2 10 4 16 6 14 8 12 10 Vector c2 after removing all elements greater than 9 from v4: 2 4 6 8 0 0 0 0 0 0
Use remove_copy_if to copy all elements greater than 3 into a multiset
/* 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()
{
list<int> coll1;
INSERT_ELEMENTS(coll1,1,6);
INSERT_ELEMENTS(coll1,1,9);
PRINT_ELEMENTS(coll1);
// copy all elements greater than 3 into a multiset
multiset<int> coll2;
remove_copy_if(coll1.begin(), coll1.end(), // source
inserter(coll2,coll2.end()), // destination
bind2nd(less<int>(),4)); // elements not copied
PRINT_ELEMENTS(coll2);
}1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 4 4 5 5 6 6 7 8 9
Use remove_copy_if to print elements without those having a value greater than 4
/* 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()
{
list<int> coll1;
INSERT_ELEMENTS(coll1,1,6);
INSERT_ELEMENTS(coll1,1,9);
PRINT_ELEMENTS(coll1);
// print elements without those having a value greater than 4
remove_copy_if(coll1.begin(), coll1.end(), // source
ostream_iterator<int>(cout," "), // destination
bind2nd(greater<int>(),4)); // removed elements
cout << endl;
}1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 1 2 3 4 1 2 3 4
