Testing indexed loops versus iterators (compile and run with -std=c++11 -O[1-3])

index_vs_iterator_test.cpp

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

int main() {
    const size_t BIG = 200000000;
    vector <int> v;
    
    for (size_t i = 0; i < BIG; i++) {
        v.push_back(i);
    }

    cout << "start" << endl;
    int n = 0;

    auto t_start = chrono::high_resolution_clock::now();

    for(vector<int>::iterator it = v.begin(); it != v.end(); ++it) {
        n += *it;
    }

    auto t_end = chrono::high_resolution_clock::now();

    cout << chrono::duration<double, milli>(t_end - t_start).count() << endl;
    
    t_start = chrono::high_resolution_clock::now();
    
    for(size_t i = 0; i < v.size(); ++i) {
        n += v[i];
    }

    t_end = chrono::high_resolution_clock::now();

    cout << chrono::duration<double, milli>(t_end - t_start).count() << endl;

    return n != 0;
}

Code heavily based on a random stackoverflow topic about the subject.

I modified the time measuring so it uses chrono instead of clock.