remove_copy_if()

Library:  Algorithms

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Algorithm that copies all elements other than those that satisfy a given predicate from one range to another

#include <algorithm>

namespace std {
  template <class InputIterator,
            class OutputIterator,
            class Predicate>
  OutputIterator remove_copy_if(InputIterator start,
                                InputIterator finish,
                                OutputIterator result,
                                Predicate pred);
}

The remove_copy_if() algorithm copies all the elements referred to by the iterator i in the range [start, finish) for which the following condition does not hold: pred(*i) == true. remove_copy_if() returns an iterator that points to the end of the resulting range. remove_copy_if() is stable, which means that the relative order of the elements in the resulting range is the same as their relative order in the original range.

Exactly finish - start applications of the corresponding predicate are done.

//
//  remove.cpp
//

#include <algorithm>    // for copy, remove, remove_copy, remove_if
#include <functional>   // for unary_function
#include <iostream>     // for cout, endl
#include <iterator>     // for ostream_iterator
#include <vector>       // for vector

 
template<class Arg>
struct not_zero: public std::unary_function<Arg, bool>
{
    bool operator() (const Arg &a) const {
        return a != 0;
    }
};


int main ()
{
    // For convenience.
    typedef std::vector<int, std::allocator<int> > Vector;
    typedef std::ostream_iterator<int, char,
                                  std::char_traits<char> >
            Iter;

    // Populate a vector with elements from an array.
    const Vector::value_type arr[] = { 1, 2, 3, 4, 5, 
                                       6, 7, 8, 9, 10};
    Vector v (arr + 0, arr + sizeof arr / sizeof *arr);

    // Write out the contents to cout.
    std::copy (v.begin (), v.end (), Iter (std::cout," "));
    std::cout << std::endl << std::endl;

    // Move the 7 to the end of the vector.
    Vector::iterator result = std::remove (v.begin (), 
                                           v.end (), 7);

    // Delete the 7 from the vector.
    v.erase (result, v.end ());

    std::copy (v.begin (), v.end (), Iter (std::cout, " "));
    std::cout << std::endl << std::endl;

    // Remove all non-zero elements beyond the fourth element.
    v.erase (std::remove_if (v.begin () + 4, v.end (), 
                             not_zero<int> ()), v.end ());

    std::copy (v.begin (), v.end (), Iter (std::cout, " "));
    std::cout << std::endl << std::endl;

    // Now remove all 3s on output.
    std::remove_copy (v.begin (), v.end (), 
                      Iter (std::cout, " "), 3);
    std::cout << std::endl << std::endl;

    // Now remove everything satisfying predicate on output.
    std::remove_copy_if (v.begin (), v.end (), 
                         Iter (std::cout, " "),
                         not_zero<int>());

    // Return 0 on success, a non-zero value on failure
    return !!v.empty ();
}


Program 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 

remove(), remove_if(), remove_copy()

ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.2.7