sort vs sort

sort vs sort

// c++ -std=c++11 -O3 sort.cpp ; ./a.out
// qsort: 674 ms
// std::sort: 1104 ms

#include <string.h>
#include <stdio.h>
#include <chrono>
#include <string>
#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;

static unsigned long long now()
{
    return chrono::system_clock::now().time_since_epoch() / chrono::milliseconds(1);
}

static int compare_strings(const void *a, const void *b)
{
    const string *s1 = *(string **)a;
    const string *s2 = *(string **)b;
    return strcmp(s1->c_str(), s2->c_str());
}

int main(void)
{
    unsigned long long start, end;
    string s(10000, 'x');
    vector<string *> v(1000000, &s);
    
    start = now();
    qsort(&v[0], v.size(), sizeof v[0], compare_strings);
    end = now();
    printf("qsort: %llu ms\n", end - start);

    start = now();
    sort(v.begin(),v.end(),[](const string *x, const string *y) { return *x > *y; });
    end = now();
    printf("std::sort: %llu ms\n", end - start);
    
    return 0;
}