Quicksort in C++

#include <stdio.h>

void swap(int arr[], const int a, const int b) {
   int tmp = arr[a];
   arr[a] = arr[b];
   arr[b] = tmp;
}

int partition(int arr[], int low, int high) {
   int pivot = arr[high];
   int i = low;

   for(int j = low; j < high; ++j) {
       if(arr[j] < pivot) {
           swap(arr, i, j);
           ++i;
       }
   }
   swap(arr, i, high);
   return i;
}

void quicksort(int arr[], int low, int high) {
   if(low < high) {
       int p = partition(arr, low, high);

       quicksort(arr, low, p - 1);
       quicksort(arr, p + 1, high);
   }
}

void sort(int arr[], const int size) {
   quicksort(arr, 0, size - 1);
}

// Demo:
int main() {
   // Test array:
   int a[] = {4, 8, 5, 1, 2, 0, 9};
   // Get the number of elements in the array:
   int s = sizeof(a) / sizeof(a[0]);

   // Sort the array:
   sort(a, s);

   for(int i = 0; i < s; ++i) {
       printf("%d ", a[i]);
   }
   printf("\n");

   return 0;
}