C++/STL Algorithms Modifying sequence operations/remove copy if

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Copy elements from one vector to another vector, removing elements greater than 9 in the process

<source lang="cpp">

  1. include <iostream>

using std::cout; using std::endl;

  1. include <algorithm>
  2. include <vector>
  3. 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.
*/
  1. include <iostream>
  2. include <vector>
  3. include <deque>
  4. include <list>
  5. include <set>
  6. include <map>
  7. include <string>
  8. include <algorithm>
  9. include <iterator>
  10. include <functional>
  11. 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.
*/
  1. include <iostream>
  2. include <vector>
  3. include <deque>
  4. include <list>
  5. include <set>
  6. include <map>
  7. include <string>
  8. include <algorithm>
  9. include <iterator>
  10. include <functional>
  11. 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>