remove_copy

     Algorithm

Move desired elements to the front of a container, and return an iterator that describes where the sequence of desired elements ends.

Contents

• Synopsis
• Description
• Complexity
• Example
• Warning
• See Also

#include <algorithm>

template <class InputIterator,
          class OutputIterator,
          class T>
 OutputIterator remove_copy (InputIterator first,
                             InputIterator last,
                             OutputIterator result,
                             const T& value);

The remove_copy algorithm copies all the elements referred to by the iterator i in the range [first, last) for which the following corresponding condition does not hold: *i == value. remove_copy returns the end of the resulting range. remove_copy is stable, that is, the relative order of the elements in the resulting range is the same as their relative order in the original range. The elements in the original sequence are not altered by remove_copy.

Exactly last1 - first1 applications of the corresponding predicate are done.

//
// remove.cpp
//
 #include <algorithm>
 #include <vector>
 #include <iterator>
 #include <iostream.h>
 template<class Arg>
 struct all_true : public unary_function<Arg, bool>
 {
   bool operator() (const Arg&) { return 1; }
 };
 int main ()
 {
   int arr[10] = {1,2,3,4,5,6,7,8,9,10};
   vector<int> v(arr+0, arr+10);
   copy(v.begin(),v.end(),ostream_iterator<int>(cout," "));
   cout << endl << endl;
   //
   // Remove the 7.
   //
   vector<int>::iterator result = remove(v.begin(), v.end(), 7);
   //
   // Delete dangling elements from the vector.
   //
   v.erase(result, v.end());
   copy(v.begin(),v.end(),ostream_iterator<int>(cout," "));
   cout << endl << endl;
   //
   // Remove everything beyond the fourth element.
   //
   result = remove_if(v.begin()+4, v.begin()+8, all_true<int>());
   //
   // Delete dangling elements.
   //
   v.erase(result, v.end());
   copy(v.begin(),v.end(),ostream_iterator<int>(cout," "));
   cout << endl << endl;
   //
   // Now remove all 3s on output.
   // 
   remove_copy(v.begin(), v.end(),                ostream_iterator<int>(cout," "), 3);

   cout << endl << endl;
   //
   // Now remove everything satisfying predicate on output.
   // Should yield a NULL vector.
   //
   remove_copy_if(v.begin(), v.end(),                   ostream_iterator<int>(cout," "),

                  all_true<int>());
 
   return 0;
 }

Output :
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 8 9 10
1 2 3 4
1 2 4

If your compiler does not support default template parameters, you need to always supply the Allocator template argument. For instance, you will need to write :

vector<int, allocator>

instead of :

vector<int>

remove, remove_if, remove_copy_if