The program is separated in main.cpp, quicksort.cpp, partition.cpp and swap.cpp. There is also a header file to each .cpp file. The idea is from this site.

As you can see, I tried to be very modular. I think instead of having swap.cpp I could've simply used std::swap, right?

But the more important thing is, that I'd like to know how I can improve this quicksort algorithm or how to improve my program in general (not only the algorithm itself).

My three .hpp files are looking like this:

#ifndef __qs__name__
#define __qs__name__

#include <vector>

//protype

#endif 

partition.cpp:

#include "partition.hpp"
#include "swap.hpp"

int partition(std::vector<int>& v, int ileft, int iright, int ipivot)
{
  int i = ileft, j = iright;

  while (i <= j)
  {
    while (v[i] < ipivot)
      i++;

    while (v[j] > ipivot)
      j--;
        
    if (i <= j)
    {
      swap(v, i, j); 
      i++; 
      j--;
    }
  } 
 
  return j;
}

quicksort.cpp:

#include "quicksort.hpp"
#include "partition.hpp"

void quicksort(std::vector<int>& v, int ileft, int iright)
{
  int p, ipivot = v[iright]; // v[(ileft + iright) / 2];

  p = partition(v, ileft, iright, ipivot);

  if(ileft < p) 
    quicksort(v, ileft, p);

  if((p + 1) < iright) 
    quicksort(v, p + 1, iright);
}

swap.cpp:

#include "swap.hpp"

void swap(std::vector<int>& v, int i, int j) 
{
  int temp = v[i];

  v[i] = v[j];
  v[j] = temp;
}

main.cpp:

#include <vector>

#include "partition.hpp"
#include "quicksort.hpp"
#include "swap.hpp"


int main()
{
  std::vector<int> v;
  v.push_back(7);
  v.push_back(10);
  v.push_back(11);
  v.push_back(1); 
  /*v.push_back(-4543);
  v.push_back(88);
  v.push_back(5);
  v.push_back(3);
  v.push_back(31);
  v.push_back(34);
  v.push_back(7);*/


  for (int i = 0; i < v.size(); i++)
    std::cout << v[i] << std::endl;

  quicksort(v, 0, v.size()-1);
  std::cout << "\n";

  for (int i = 0; i < v.size(); i++)
    std::cout << v[i] << std::endl;

  return 0;
}