c++ - Shortest way to obtain a sublist of a sorted list of values lying in a certain interval -


today asking myself might shortest possible code obtain values in sorted vector std::vector<double>, greater or equal a , smaller or equal b.

my first approach following:

#include <vector> #include <algorithm> #include <iterator> #include <iostream>  // returns values in sortedvalues being greater equal start , smaller equal end; std::vector<double> cutvalues(const std::vector<double>& sortedvalues, double start, double end) {     std::vector<double> ret;      auto startiter=std::lower_bound(sortedvalues.begin(), sortedvalues.end(), start);     auto stopiter = std::upper_bound(sortedvalues.begin(), sortedvalues.end(), end);     std::copy(startiter, stopiter, std::back_inserter(ret));     return ret; }  int main(int argc, char **args) {     {         auto ret = cutvalues({ 0.1,0.2,0.3 }, 0.1, 0.3);         std::copy(ret.begin(), ret.end(), std::ostream_iterator<double>(std::cout, ","));         std::cout << std::endl;     }     {         auto ret = cutvalues({ 0.12,0.2,0.31 }, 0.1, 0.3);         std::copy(ret.begin(), ret.end(), std::ostream_iterator<double>(std::cout, ","));         std::cout << std::endl;     }     {         auto ret = cutvalues({ 0.1,0.2,0.3 }, 0.2, 0.2);         std::copy(ret.begin(), ret.end(), std::ostream_iterator<double>(std::cout, ","));         std::cout << std::endl;     } }

my second thought simple following:

std::vector<double> cutvalues2(const std::vector<double>& sortedvalues, double start, double end) {     std::vector<double> ret;     std::copy_if(sortedvalues.begin(), sortedvalues.end(), std::back_inserter(ret), [&start, &end](auto v) { return v >= start && v <= end; });     return ret; }

but considering case of removing small portions large vector might have efficiency issues.

now i'm asking myself, if there there better ways it?

a bit changed first version: 

std::vector<double> cutvalues(const std::vector<double>& sortedvalues, double start, double end) {     auto startiter = std::lower_bound(sortedvalues.begin(), sortedvalues.end(), start);     auto stopiter = std::upper_bound(startiter, sortedvalues.end(), end);     return std::vector<double>(startiter, stopiter); }

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