iterative_bsearch.cpp

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

bool binary_search(vector<int>::iterator lower, vector<int>::iterator upper, int k)
{
  auto mid = next(lower, distance(lower, upper)/2);
  while(lower <= upper)
  {
    if(*mid == k) return true;
    else if(* mid < k)
    {
      lower = next(mid);
    } else {
      upper = prev(mid);
    }
    mid = next(lower, distance(lower, upper)/2);
  }
  return false;
}

int main()
{
  vector<int> vec{-7, 5, 0, -5, 10, 50};
  sort(begin(vec), end(vec));
  cout << boolalpha << binary_search(begin(vec), end(vec), 10) << '\n';
  return 0;
}