remove_copy_if

Article
04/22/2008

Copies elements from a source range to a destination range, except that satisfying a predicate are not copied, without disturbing the order of the remaining elements and returning the end of a new destination range.

template<class InputIterator, class OutputIterator, class Predicate>
   OutputIterator remove_copy_if(
      InputIterator _First, 
      InputIterator _Last, 
      OutputIterator _Result,
      Predicate _Pred
   );

Parameters

_First
An input iterator addressing the position of the first element in the range from which elements are being removed.
_Last
An input iterator addressing the position one past the final element in the range from which elements are being removed.
_Result
An output iterator addressing the position of the first element in the destination range to which elements are being removed.
_Pred
The unary predicate that must be satisfied is the value of an element is to be replaced.

Return Value

A forward iterator addressing the new end position of the destination range, one past the final element of the remnant sequence free of the elements satisfying the predicate.

Remarks

The source range referenced must be valid; all pointers must be dereferenceable and within the sequence the last position is reachable from the first by incrementation.

There must be enough space in the destination range to contain the remnant elements that will be copied after elements of the specified value are removed.

The order of the elements not removed remains stable.

The operator== used to determine the equality between elements must impose an equivalence relation between its operands.

The complexity is linear: there are (_Last – _First) comparisons for equality and at most (_Last – _First) assignments.

remove_copy_if has two related forms:

For information on how these functions behave, see Checked Iterators.

Example

// alg_remove_copy_if.cpp
// compile with: /EHsc
#include <vector>
#include <algorithm>
#include <iostream>

bool greater6 ( int value ) {
   return value >6;
}

int main() {
   using namespace std;
   vector <int> v1, v2(10);
   vector <int>::iterator Iter1, Iter2, new_end;

   int i;
   for ( i = 0 ; i <= 9 ; i++ )
      v1.push_back( i );

   int ii;
   for ( ii = 0 ; ii <= 3 ; ii++ )
      v1.push_back( 7 );
   
   random_shuffle ( v1.begin( ), v1.end( ) );
   cout << "The original vector v1 is:      ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   // Remove elements with a value greater than 6
   new_end = remove_copy_if ( v1.begin( ), v1.end( ), 
      v2.begin( ), greater6 );

   cout << "After the appliation of remove_copy_if to v1,\n "
        << "vector v1 is left unchanged as ( " ;
   for ( Iter1 = v1.begin( ) ; Iter1 != v1.end( ) ; Iter1++ )
      cout << *Iter1 << " ";
   cout << ")." << endl;

   cout << "Vector v2 is a copy of v1 with values greater "
        << "than 6 removed:\n ( " ;
   for ( Iter2 = v2.begin( ) ; Iter2 != new_end ; Iter2++ )
      cout << *Iter2 << " ";
   cout << ")." << endl;
}

Sample Output

The original vector v1 is:      ( 7 1 9 2 0 7 7 3 4 6 8 5 7 7 ).
After the appliation of remove_copy_if to v1,
 vector v1 is left unchanged as ( 7 1 9 2 0 7 7 3 4 6 8 5 7 7 ).
Vector v2 is a copy of v1 with values greater than 6 removed:
 ( 1 2 0 3 4 6 5 ).

Requirements

Header: <algorithm>

Namespace: std

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