C++/STL Algorithms Modifying sequence operations/remove copy if
Copy elements from one vector to another vector, removing elements greater than 9 in the process
<source lang="cpp">
- 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 */ </source>
Use remove_copy_if to copy all elements greater than 3 into a multiset
<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() {
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
*/ </source>
Use remove_copy_if to print elements without those having a value greater than 4
<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() {
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
*/ </source>