Filter std::vector of std::string's

Question

How can I produce an output vector which filters an input vector based on whether it starts with a certain sub-string or not. I'm using c++98 and boost.

This is as far as I got:

std::string stringToFilterBy("2");
std::vector<std::string> input = boost::assign::list_of("1")("2")("22")("33")("222");
std::vector<int> output;
boost::copy( input | boost::adaptors::filtered(boost::starts_with), std::back_inserter(output) );

Answer 1

You can use std::remove_copy_if instead:

#include <algorithm>
#include <iterator>
#include <vector>

struct filter : public std::unary_function<std::string, bool> {
    filter(const std::string &by) : by_(by) {}
    bool operator()(const std::string &s) const {
        return s.find(by_) == 0;
    }

    std::string by_;
};

std::vector<std::string> in, out;
std::remove_copy_if(in.begin(), in.end(), std::back_inserter(out),
                    std::not1(filter("2")));