quick sort in C language

/*
Example: Array quicksort in C language
*/
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <stdbool.h>
#include <errno.h>
#include <unistd.h>

void swap(int* a, int* b)
{
    int t = *a;
    *a = *b;
    *b = t;
}

int partition (int arr[], int low, int high)
{
    int pivot = arr[high];
    int i = (low - 1);
    for (int j = low; j <= high- 1; j++)
    {
        if (arr[j] <= pivot)
        {
            i++;
            swap(&arr[i], &arr[j]);
        }
    }
    swap(&arr[i + 1], &arr[high]);
    return (i + 1);
}

void quickSort(int arr[], int low, int high)
{
    if (low < high)
    {
        int pi = partition(arr, low, high);
        quickSort(arr, low, pi - 1);
        quickSort(arr, pi + 1, high);
    }
}
void printArray(int arr[], int size)
{
    int i;
    for (i=0; i < size; i++)
    printf("%d ", arr[i]);
    printf("\n");
}

int main()
{
    int arr[] = {1,5,2,4,8,9,7,2,3,23,21,15,11};
    int n = sizeof(arr)/sizeof(arr[0]);
    printf("before sort: \n");
    printArray(arr, n);
    quickSort(arr, 0, n-1);
    printf("quick sort: \n");
    printArray(arr, n);
    return 0;
}