boost::remove_copy_if

#include <functional>
#include <iostream>
#include <vector>
#include <boost/range/algorithm.hpp>

bool is_3_or_4(int i) {
    return i == 3 || i == 4;
}

int main() {
    std::vector<int> vec = {1, 2, 3, 4, 5};
    std::vector<int> output;

    // remove_copy_if() wraps std::remove_copy_if(). Elements in the input
    // range are copied to the output iterator if they are not filtered by the
    // predicate function. The input is not modified.
    // Returns an iterator to the end of the output range.
    boost::remove_copy_if(vec, std::back_inserter(output), is_3_or_4);

    std::cout << "input vector after remove_copy_if(): ";
    boost::range::copy(vec, std::ostream_iterator<int>(std::cout, " "));
    std::cout << std::endl;

    std::cout << "output vector after remove_copy_if(): ";
    boost::range::copy(output, std::ostream_iterator<int>(std::cout, " "));
    std::cout << std::endl;
    return 0;
}

input vector after remove_copy_if(): 1 2 3 4 5 
output vector after remove_copy_if(): 1 2 5